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Sample records for dispersal connects fish

  1. Connectivity patterns of coastal fishes following different dispersal scenarios across a transboundary marine protected area (Bonifacio strait, NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Koeck, Barbara; Gérigny, Olivia; Durieux, Eric Dominique Henri; Coudray, Sylvain; Garsi, Laure-Hélène; Bisgambiglia, Paul-Antoine; Galgani, François; Agostini, Sylvia

    2015-03-01

    The Strait of Bonifacio constitutes one of the rare transboundary Marine Protected Areas (MPA) of the Mediterranean Sea (between Sardinia, Italy and Corsica, France). Based on the hypothesis that no-take zones will produce more fish larvae, compared to adjacent fished areas, we modeled the outcome of larvae released by coastal fishes inside the no-take zones of the MPA in order to: (1) characterize the dispersal patterns across the Strait of Bonifacio; (2) identify the main potential settlement areas; (3) quantify the connectivity and the larval supply from the MPAs to the surrounding areas. A high resolution hydrodynamic model (MARS 3D, Corse 400 m) combined to an individual based model (Ichthyop software) was used to model the larval dispersal of fish following various scenarios (Pelagic Larval Duration PLD and release depth) over the main spawning period (i.e. between April and September). Dispersal model outputs were then compared with those obtained from an ichthyoplankton sampling cruise performed in August 2012. There was a significant influence of PLD to the connectivity between coastal areas. The synchronization between spawning and hydrodynamic conditions appeared to be determinant in the larval transport success. Biotic and abiotic parameters affecting the dispersal dynamic of fish larvae within the Strait of Bonifacio were identified and synthesis maps were established as a tool for conservation planning.

  2. How Nemo finds home: the neuroecology of dispersal and of population connectivity in larvae of marine fishes.

    PubMed

    Leis, Jeffrey M; Siebeck, Ulrike; Dixson, Danielle L

    2011-11-01

    Nearly all demersal teleost marine fishes have pelagic larval stages lasting from several days to several weeks, during which time they are subject to dispersal. Fish larvae have considerable swimming abilities, and swim in an oriented manner in the sea. Thus, they can influence their dispersal and thereby, the connectivity of their populations. However, the sensory cues marine fish larvae use for orientation in the pelagic environment remain unclear. We review current understanding of these cues and how sensory abilities of larvae develop and are used to achieve orientation with particular emphasis on coral-reef fishes. The use of sound is best understood; it travels well underwater with little attenuation, and is current-independent but location-dependent, so species that primarily utilize sound for orientation will have location-dependent orientation. Larvae of many species and families can hear over a range of ~100-1000 Hz, and can distinguish among sounds. They can localize sources of sounds, but the means by which they do so is unclear. Larvae can hear during much of their pelagic larval phase, and ontogenetically, hearing sensitivity, and frequency range improve dramatically. Species differ in sensitivity to sound and in the rate of improvement in hearing during ontogeny. Due to large differences among-species within families, no significant differences in hearing sensitivity among families have been identified. Thus, distances over which larvae can detect a given sound vary among species and greatly increase ontogenetically. Olfactory cues are current-dependent and location-dependent, so species that primarily utilize olfactory cues will have location-dependent orientation, but must be able to swim upstream to locate sources of odor. Larvae can detect odors (e.g., predators, conspecifics), during most of their pelagic phase, and at least on small scales, can localize sources of odors in shallow water, although whether they can do this in pelagic

  3. How restructuring river connectivity changes freshwater fish biodiversity and biogeography

    USGS Publications Warehouse

    Lynch, Heather L.; Grant, Evan H. Campbell; Muneepeerakul, Rachata; Arunachalam, Muthukumarasamy; Rodriguez-Iturbe, Ignacio; Fagan, William F.

    2011-01-01

    Interbasin water transfer projects, in which river connectivity is restructured via man-made canals, are an increasingly popular solution to address the spatial mismatch between supply and demand of fresh water. However, the ecological consequences of such restructuring remain largely unexplored, and there are no general theoretical guidelines from which to derive these expectations. River systems provide excellent opportunities to explore how network connectivity shapes habitat occupancy, community dynamics, and biogeographic patterns. We apply a neutral model (which assumes competitive equivalence among species within a stochastic framework) to an empirically derived river network to explore how proposed changes in network connectivity may impact patterns of freshwater fish biodiversity. Without predicting the responses of individual extant species, we find the addition of canals connecting hydrologically isolated river basins facilitates the spread of common species and increases average local species richness without changing the total species richness of the system. These impacts are sensitive to the parameters controlling the spatial scale of fish dispersal, with increased dispersal affording more opportunities for biotic restructuring at the community and landscape scales. Connections between isolated basins have a much larger effect on local species richness than those connecting reaches within a river basin, even when those within-basin reaches are far apart. As a result, interbasin canal projects have the potential for long-term impacts to continental-scale riverine communities.

  4. Fish as vectors in the dispersal of Bythotrephes cederstroemi: Diapausing eggs survive passage through the gut

    USGS Publications Warehouse

    Jarnagin, S.T.; Swan, B.K.; Kerfoot, W.C.

    2000-01-01

    1. Bythotrephes cederstroemi (Crustacea: Onychopoda: Cercopagidae) is an introduced invertebrate predator currently spreading through the Laurentian Great Lakes region of North America. We examined a previously unsuspected way in which B. cederstroemi may be dispersed by fish by their consumption of diapausing eggs. 2. Ninety-four percentage of the mature B. cederstroemi diapausing eggs consumed by fish were egested apparently intact. This proportion is considerably above previous estimates for the ephippial eggs of Daphnia. The hatching success of diapausing eggs was compared among four categories: (a) eggs released naturally by B. cederstroemi (control, 73% hatched (b) eggs released during 'stressful confinement' (46% hatched) (c) eggs dissected from dead females (13% hatched) and (d) eggs recovered from faecal pellets following consumption by fish (viable gut passage experiment, 41% hatched). 3. Samples of small fish and B. cederstroemi were collected simultaneously. Examination of gut contents revealed that fish contained B. cederstroemi diapausing eggs and that B. cederstroemi bearing resting eggs were consumed selectively over those without eggs. Moreover, fish selected B. cederstroemi bearing mature rather than immature diapausing eggs. 4. The fact that diapausing eggs survive gut passage is important for the dispersal of B. cederstroemi. Fish often move between the pelagic and littoral zones of lakes and may thus disperse diapausing eggs widely. Fish may also move between lakes connected by river systems and can be caught and passively dispersed by anglers or piscivorous birds. Our results demonstrate the potential for fish to act as vectors in the spread of B. cederstroemi.

  5. Long-Distance Dispersal via Ocean Currents Connects Omani Clownfish Populations throughout Entire Species Range

    PubMed Central

    Claereboudt, Michel R.; Planes, Serge

    2014-01-01

    Dispersal is a crucial ecological process, driving population dynamics and defining the structure and persistence of populations. Measuring demographic connectivity between discreet populations remains a long-standing challenge for most marine organisms because it involves tracking the movement of pelagic larvae. Recent studies demonstrate local connectivity of reef fish populations via the dispersal of planktonic larvae, while biogeography indicates some larvae must disperse 100–1000 s kilometres. To date, empirical measures of long-distance dispersal are lacking and the full scale of dispersal is unknown. Here we provide the first measure of long-distance dispersal in a coral reef fish, the Omani clownfish Amphiprion omanensis, throughout its entire species range. Using genetic assignment tests we demonstrate bidirectional exchange of first generation migrants, with subsequent social and reproductive integration, between two populations separated by over 400 km. Immigration was 5.4% and 0.7% in each region, suggesting a biased southward exchange, and matched predictions from a physically-coupled dispersal model. This rare opportunity to measure long-distance dispersal demonstrates connectivity of isolated marine populations over distances of 100 s of kilometres and provides a unique insight into the processes of biogeography, speciation and adaptation. PMID:25229550

  6. Connectivity from a different perspective: comparing seed dispersal kernels in connected vs. unfragmented landscapes.

    PubMed

    Herrmann, John D; Carlo, Tomas A; Brudvig, Lars A; Damschen, Ellen I; Haddad, Nick M; Levey, Douglas J; Orrock, John L; Tewksbury, Joshua J

    2016-05-01

    Habitat fragmentation can create significant impediments to dispersal. A technique to increase dispersal between otherwise isolated fragments is the use of corridors. Although previous studies have compared dispersal between connected fragments to dispersal between unconnected fragments, it remains unknown how dispersal between fragments connected by a corridor compares to dispersal in unfragmented landscapes. To assess the extent to which corridors can restore dispersal in fragmented landscapes to levels observed in unfragmented landscapes, we employed a stable-isotope marking technique to track seeds within four unfragmented landscapes and eight experimental landscapes with fragments connected by corridors. We studied two wind- and two bird-dispersed plant species, because previous community-based research showed that dispersal mode explains how connectivity effects vary among species. We constructed dispersal kernels for these species in unfragmented landscapes and connected fragments by marking seeds in the center of each landscape with 'IN and then recovering marked seeds in seed traps at distances up to 200 m. For the two wind-dispersed plants, seed dispersal kernels were similar in unfragmented landscapes and connected fragments. In contrast, dispersal kernels of bird-dispersed seeds were both affected by fragmentation and differed in the direction of the impact: Morella cerifera experienced more and Rhus copallina experienced less long-distance dispersal in unfragmented than in connected landscapes. These results show that corridors can facilitate dispersal probabilities comparable to those observed in unfragmented landscapes. Although dispersal mode may provide useful broad predictions, we acknowledge that similar species may respond uniquely due to factors such as seasonality and disperser behavior. Our results further indicate that prior work has likely underestimated dispersal distances of wind-dispersed plants and that factors altering long

  7. On the evolution of dispersal via heterogeneity in spatial connectivity

    PubMed Central

    Henriques-Silva, Renato; Boivin, Frédéric; Calcagno, Vincent; Urban, Mark C.; Peres-Neto, Pedro R.

    2015-01-01

    Dispersal has long been recognized as a mechanism that shapes many observed ecological and evolutionary processes. Thus, understanding the factors that promote its evolution remains a major goal in evolutionary ecology. Landscape connectivity may mediate the trade-off between the forces in favour of dispersal propensity (e.g. kin-competition, local extinction probability) and those against it (e.g. energetic or survival costs of dispersal). It remains, however, an open question how differing degrees of landscape connectivity may select for different dispersal strategies. We implemented an individual-based model to study the evolution of dispersal on landscapes that differed in the variance of connectivity across patches ranging from networks with all patches equally connected to highly heterogeneous networks. The parthenogenetic individuals dispersed based on a flexible logistic function of local abundance. Our results suggest, all else being equal, that landscapes differing in their connectivity patterns will select for different dispersal strategies and that these strategies confer a long-term fitness advantage to individuals at the regional scale. The strength of the selection will, however, vary across network types, being stronger on heterogeneous landscapes compared with the ones where all patches have equal connectivity. Our findings highlight how landscape connectivity can determine the evolution of dispersal strategies, which in turn affects how we think about important ecological dynamics such as metapopulation persistence and range expansion. PMID:25673685

  8. Dispersal Patterns of Coastal Fish: Implications for Designing Networks of Marine Protected Areas

    PubMed Central

    Di Franco, Antonio; Gillanders, Bronwyn M.; De Benedetto, Giuseppe; Pennetta, Antonio; De Leo, Giulio A.; Guidetti, Paolo

    2012-01-01

    Information about dispersal scales of fish at various life history stages is critical for successful design of networks of marine protected areas, but is lacking for most species and regions. Otolith chemistry provides an opportunity to investigate dispersal patterns at a number of life history stages. Our aim was to assess patterns of larval and post-settlement (i.e. between settlement and recruitment) dispersal at two different spatial scales in a Mediterranean coastal fish (i.e. white sea bream, Diplodus sargus sargus) using otolith chemistry. At a large spatial scale (∼200 km) we investigated natal origin of fish and at a smaller scale (∼30 km) we assessed “site fidelity” (i.e. post-settlement dispersal until recruitment). Larvae dispersed from three spawning areas, and a single spawning area supplied post-settlers (proxy of larval supply) to sites spread from 100 to 200 km of coastline. Post-settlement dispersal occurred within the scale examined of ∼30 km, although about a third of post-settlers were recruits in the same sites where they settled. Connectivity was recorded both from a MPA to unprotected areas and vice versa. The approach adopted in the present study provides some of the first quantitative evidence of dispersal at both larval and post-settlement stages of a key species in Mediterranean rocky reefs. Similar data taken from a number of species are needed to effectively design both single marine protected areas and networks of marine protected areas. PMID:22355388

  9. Evidence for fish dispersal from spatial analysis of stream network topology

    USGS Publications Warehouse

    Hitt, N.P.; Angermeier, P.L.

    2008-01-01

    Developing spatially explicit conservation strategies for stream fishes requires an understanding of the spatial structure of dispersal within stream networks. We explored spatial patterns of stream fish dispersal by evaluating how the size and proximity of connected streams (i.e., stream network topology) explained variation in fish assemblage structure and how this relationship varied with local stream size. We used data from the US Environmental Protection Agency's Environmental Monitoring and Assessment Program in wadeable streams of the Mid-Atlantic Highlands region (n = 308 sites). We quantified stream network topology with a continuous analysis based on the rate of downstream flow accumulation from sites and with a discrete analysis based on the presence of mainstem river confluences (i.e., basin area >250 km2) within 20 fluvial km (fkm) from sites. Continuous variation in stream network topology was related to local species richness within a distance of ???10 fkm, suggesting an influence of fish dispersal within this spatial grain. This effect was explained largely by catostomid species, cyprinid species, and riverine species, but was not explained by zoogeographic regions, ecoregions, sampling period, or spatial autocorrelation. Sites near mainstem river confluences supported greater species richness and abundance of catostomid, cyprinid, and ictalurid fishes than did sites >20 fkm from such confluences. Assemblages at sites on the smallest streams were not related to stream network topology, consistent with the hypothesis that local stream size regulates the influence of regional dispersal. These results demonstrate that the size and proximity of connected streams influence the spatial distribution of fish and suggest that these influences can be incorporated into the designs of stream bioassessments and reserves to enhance management efficacy. ?? 2008 by The North American Benthological Society.

  10. A capture-recapture model of amphidromous fish dispersal.

    PubMed

    Smith, W E; Kwak, T J

    2014-04-01

    Adult movement scale was quantified for two tropical Caribbean diadromous fishes, bigmouth sleeper Gobiomorus dormitor and mountain mullet Agonostomus monticola, using passive integrated transponders (PITs) and radio-telemetry. Large numbers of fishes were tagged in Río Mameyes, Puerto Rico, U.S.A., with PITs and monitored at three fixed locations over a 2·5 year period to estimate transition probabilities between upper and lower elevations and survival probabilities with a multistate Cormack-Jolly-Seber model. A sub-set of fishes were tagged with radio-transmitters and tracked at weekly intervals to estimate fine-scale dispersal. Changes in spatial and temporal distributions of tagged fishes indicated that neither G. dormitor nor A. monticola moved into the lowest, estuarine reaches of Río Mameyes during two consecutive reproductive periods, thus demonstrating that both species follow an amphidromous, rather than catadromous, migratory strategy. Further, both species were relatively sedentary, with restricted linear ranges. While substantial dispersal of these species occurs at the larval stage during recruitment to fresh water, the results indicate minimal dispersal in spawning adults. Successful conservation of diadromous fauna on tropical islands requires management at both broad basin and localized spatial scales. PMID:24673127

  11. A capture-recapture model of amphidromous fish dispersal

    USGS Publications Warehouse

    Smith, W.; Kwak, Thomas J.

    2014-01-01

    Adult movement scale was quantified for two tropical Caribbean diadromous fishes, bigmouth sleeper Gobiomorus dormitor and mountain mullet Agonostomus monticola, using passive integrated transponders (PITs) and radio-telemetry. Large numbers of fishes were tagged in Rio Mameyes, Puerto Rico, U.S.A., with PITs and monitored at three fixed locations over a 2-5 year period to estimate transition probabilities between upper and lower elevations and survival probabilities with a multistate Cormack-Jolly-Seber model. A sub-set of fishes were tagged with radio-transmitters and tracked at weekly intervals to estimate fine-scale dispersal. Changes in spatial and temporal distributions of tagged fishes indicated that neither G. dormitor nor A. monticola moved into the lowest, estuarine reaches of Rio Mameyes during two consecutive reproductive periods, thus demonstrating that both species follow an amphidromous, rather than catadromous, migratory strategy. Further, both species were relatively sedentary, with restricted linear ranges. While substantial dispersal of these species occurs at the larval stage during recruitment to fresh water, the results indicate minimal dispersal in spawning adults. Successful conservation of diadromous fauna on tropical islands requires management at both broad basin and localized spatial scales.

  12. Sex-biased dispersal in a salmonid fish.

    PubMed Central

    Hutchings, Jeffrey A; Gerber, Leah

    2002-01-01

    We tested the hypothesis that dispersal is sex biased in an unexploited population of brook trout, Salvelinus fontinalis, on Cape Race, Newfoundland, Canada. Based on the assumptions that trout are promiscuous and that reproductive success is limited primarily by either number of mates (males) or fecundity (females), we predicted that males would disperse greater distances than females. We also tested the hypothesis that trout populations comprise stationary and mobile individuals, predicting that males have greater mobility than females. Based on a mark-recapture study of 943 individually tagged fishes, 191 of which were recaptured over 5 years, we find strong support for our hypothesis of male-biased dispersal in brook trout. Averaged among all 11 resampling periods, males dispersed 2.5 times as far as females; during the spawning period only, male dispersal exceeded that by females almost fourfold. Both sexes were heterogeneous with respect to movement, with a lower incidence of mobility among females (29.6%) than males (41.1%); mobile males dispersed six times further than mobile females. We conclude that this sex bias reduces mate competition among male kin and decreases the probability that males will reproduce with related females. PMID:12495493

  13. Kinship analyses identify fish dispersal events on a temperate coastline.

    PubMed

    Schunter, C; Pascual, M; Garza, J C; Raventos, N; Macpherson, E

    2014-06-22

    Connectivity is crucial for the persistence and resilience of marine species, the establishment of networks of marine protected areas and the delineation of fishery management units. In the marine environment, understanding connectivity is still a major challenge, due to the technical difficulties of tracking larvae. Recently, parentage analysis has provided a means to address this question effectively. To be effective, this method requires limited adult movement and extensive sampling of parents, which is often not possible for marine species. An alternative approach that is less sensitive to constraints in parental movement and sampling could be the reconstruction of sibships. Here, we directly measure connectivity and larval dispersal in a temperate marine ecosystem through both analytical approaches. We use data from 178 single nucleotide polymorphism markers to perform parentage and sibship reconstruction of the black-faced blenny (Tripterygion delaisi) from an open coastline in the Mediterranean Sea. Parentage analysis revealed a decrease in dispersal success in the focal area over 1 km distance and approximately 6.5% of the juveniles were identified as self-recruits. Sibship reconstruction analysis found that, in general, full siblings did not recruit together to the same location, and that the largest distance between recruitment locations was much higher (11.5 km) than found for parent-offspring pairs (1.2 km). Direct measurements of dispersal are essential to understanding connectivity patterns in different marine habitats, and show the degree of self-replenishment and sustainability of populations of marine organisms. We demonstrate that sibship reconstruction allows direct measurements of dispersal and family structure in marine species while being more easily applied in those species for which the collection of the parental population is difficult or unfeasible. PMID:24812064

  14. Dispersal Limitations on Fish Community Recovery Following Long-term Water Quality Remediation

    DOE PAGESBeta

    McManamay, Ryan A.; Jett, Robert T.; Ryon, Michael G.; Gregory, Scott M.; Stratton, Sally H.; Peterson, Mark J.

    2016-02-22

    Holistic restoration approaches, such as water quality remediation, are likely to meet conservation objectives because they are typically implemented at watershed scales, as opposed to individual stream reaches. However, habitat fragmentation may impose constraints on the ecological effectiveness of holistic restoration strategies by limiting colonization following remediation. We questioned the importance of dispersal limitations to fish community recovery following long-term water quality remediation and species reintroductions across the White Oak Creek (WOC) watershed near Oak Ridge, Tennessee (USA). Long-term (26 years) responses in fish species richness and biomass to water quality remediation were evaluated in light of habitat fragmentation andmore » population isolation from instream barriers, which varied in their passage potential. In addition, ordination techniques were used to determine the relative importance of habitat connectivity and water quality, in explaining variation fish communities relative to environmental fluctuations, i.e. streamflow. Ecological recovery (changes in richness) at each site was negatively related to barrier index, a measure of community isolation by barriers relative to stream distance. Following species reintroductions, dispersal by fish species was consistently in the downstream direction and upstream passage above barriers was non-existent. The importance of barrier index in explaining variation in fish communities was stronger during higher flow conditions, but decreased over time an indication of increasing community stability and loss of seasonal migrants. Compared to habitat fragmentation, existing water quality concerns (i.e., outfalls, point source discharges) were unrelated to ecological recovery, but explained relatively high variation in community dynamics. Our results suggest that habitat fragmentation limited the ecological effectiveness of intensive water quality remediation efforts and fish reintroduction

  15. Matching spatial property rights fisheries with scales of fish dispersal.

    PubMed

    White, Crow; Costello, Christopher

    2011-03-01

    Regulation of fisheries using spatial property rights can alleviate competition for high-value patches that hinders economic efficiency in quota-based, rights-based, and open-access management programs. However, efficiency gains erode when delineation of spatial rights constitutes incomplete ownership of the resource, thereby degrading its local value and promoting overexploitation. Incomplete ownership may be particularly prevalent in the spatial management of mobile fishery species. We developed a game-theoretic bioeconomic model of spatial property rights representing territorial user rights fisheries (TURF) management of nearshore marine fish and invertebrate species with mobile adult and larval life history stages. Strategic responses by fisheries in neighboring management units result in overexploitation of the stock and reduced yields for each fishery compared with those attainable without resource mobility or with coordination or sole control in fishing effort. High dispersal potential of the larval stage, a common trait among nearshore fishery species, coupled with scaling of management units to only capture adult mobility, a common characteristic of many nearshore TURF programs, in particular substantially reduced stock levels and yields. In a case study of hypothetical TURF programs of nearshore fish and invertebrate species, management units needed to be tens of kilometers in alongshore length to minimize larval export and generate reasonable returns to fisheries. Cooperation and quota regulations represent solutions to the problem that need to be quantified in cost and integrated into the determination of the acceptability of spatial property rights management of fisheries. PMID:21563568

  16. Evaluating the effectiveness of restoring longitudinal connectivity for stream fish communities: towards a more holistic approach.

    PubMed

    Tummers, Jeroen S; Hudson, Steve; Lucas, Martyn C

    2016-11-01

    A more holistic approach towards testing longitudinal connectivity restoration is needed in order to establish that intended ecological functions of such restoration are achieved. We illustrate the use of a multi-method scheme to evaluate the effectiveness of 'nature-like' connectivity restoration for stream fish communities in the River Deerness, NE England. Electric-fishing, capture-mark-recapture, PIT telemetry and radio-telemetry were used to measure fish community composition, dispersal, fishway efficiency and upstream migration respectively. For measuring passage and dispersal, our rationale was to evaluate a wide size range of strong swimmers (exemplified by brown trout Salmo trutta) and weak swimmers (exemplified by bullhead Cottus perifretum) in situ in the stream ecosystem. Radio-tracking of adult trout during the spawning migration showed that passage efficiency at each of five connectivity-restored sites was 81.3-100%. Unaltered (experimental control) structures on the migration route had a bottle-neck effect on upstream migration, especially during low flows. However, even during low flows, displaced PIT tagged juvenile trout (total n=153) exhibited a passage efficiency of 70.1-93.1% at two nature-like passes. In mark-recapture experiments juvenile brown trout and bullhead tagged (total n=5303) succeeded in dispersing upstream more often at most structures following obstacle modification, but not at the two control sites, based on a Laplace kernel modelling approach of observed dispersal distance and barrier traverses. Medium-term post-restoration data (2-3years) showed that the fish assemblage remained similar at five of six connectivity-restored sites and two control sites, but at one connectivity-restored headwater site previously inhabited by trout only, three native non-salmonid species colonized. We conclude that stream habitat reconnection should support free movement of a wide range of species and life stages, wherever retention of such

  17. Larval retention and connectivity among populations of corals and reef fishes: history, advances and challenges

    NASA Astrophysics Data System (ADS)

    Jones, G. P.; Almany, G. R.; Russ, G. R.; Sale, P. F.; Steneck, R. S.; van Oppen, M. J. H.; Willis, B. L.

    2009-06-01

    The extent of larval dispersal on coral reefs has important implications for the persistence of coral reef metapopulations, their resilience and recovery from an increasing array of threats, and the success of protective measures. This article highlights a recent dramatic increase in research effort and a growing diversity of approaches to the study of larval retention within (self-recruitment) and dispersal among (connectivity) isolated coral reef populations. Historically, researchers were motivated by alternative hypotheses concerning the processes limiting populations and structuring coral reef assemblages, whereas the recent impetus has come largely from the need to incorporate dispersal information into the design of no-take marine protected area (MPA) networks. Although the majority of studies continue to rely on population genetic approaches to make inferences about dispersal, a wide range of techniques are now being employed, from small-scale larval tagging and paternity analyses, to large-scale biophysical circulation models. Multiple approaches are increasingly being applied to cross-validate and provide more realistic estimates of larval dispersal. The vast majority of empirical studies have focused on corals and fishes, where evidence for both extremely local scale patterns of self-recruitment and ecologically significant connectivity among reefs at scales of tens of kilometers (and in some cases hundreds of kilometers) is accumulating. Levels of larval retention and the spatial extent of connectivity in both corals and fishes appear to be largely independent of larval duration or reef size, but may be strongly influenced by geographic setting. It is argued that high levels of both self-recruitment and larval import can contribute to the resilience of reef populations and MPA networks, but these benefits will erode in degrading reef environments.

  18. Fish Utilisation of Wetland Nurseries with Complex Hydrological Connectivity

    PubMed Central

    Davis, Ben; Johnston, Ross; Baker, Ronald; Sheaves, Marcus

    2012-01-01

    The physical and faunal characteristics of coastal wetlands are driven by dynamics of hydrological connectivity to adjacent habitats. Wetlands on estuary floodplains are particularly dynamic, driven by a complex interplay of tidal marine connections and seasonal freshwater flooding, often with unknown consequences for fish using these habitats. To understand the patterns and subsequent processes driving fish assemblage structure in such wetlands, we examined the nature and diversity of temporal utilisation patterns at a species or genus level over three annual cycles in a tropical Australian estuarine wetland system. Four general patterns of utilisation were apparent based on CPUE and size-structure dynamics: (i) classic nursery utlisation (use by recently settled recruits for their first year) (ii) interrupted peristence (iii) delayed recruitment (iv) facultative wetland residence. Despite the small self-recruiting ‘facultative wetland resident’ group, wetland occupancy seems largely driven by connectivity to the subtidal estuary channel. Variable connection regimes (i.e. frequency and timing of connections) within and between different wetland units (e.g. individual pools, lagoons, swamps) will therefore interact with the diversity of species recruitment schedules to generate variable wetland assemblages in time and space. In addition, the assemblage structure is heavily modified by freshwater flow, through simultaneously curtailing persistence of the ’interrupted persistence’ group, establishing connectivity for freshwater spawned members of both the ‘facultative wetland resident’ and ‘delayed recruitment group’, and apparently mediating use of intermediate nursery habitats for marine-spawned members of the ‘delayed recruitment’ group. The diversity of utilisation pattern and the complexity of associated drivers means assemblage compositions, and therefore ecosystem functioning, is likely to vary among years depending on variations in

  19. Asymmetric connectivity of spawning aggregations of a commercially important marine fish using a multidisciplinary approach

    PubMed Central

    Jackson, Alexis; Marinone, Silvio Guido; Erisman, Brad; Moreno-Baez, Marcia; Girón-Nava, Alfredo; Pfister, Tad; Aburto-Oropeza, Octavio; Torre, Jorge

    2014-01-01

    Understanding patterns of larval dispersal is key in determining whether no-take marine reserves are self-sustaining, what will be protected inside reserves and where the benefits of reserves will be observed. We followed a multidisciplinary approach that merged detailed descriptions of fishing zones and spawning time at 17 sites distributed in the Midriff Island region of the Gulf of California with a biophysical oceanographic model that simulated larval transport at Pelagic Larval Duration (PLD) 14, 21 and 28 days for the most common and targeted predatory reef fish, (leopard grouper Mycteroperca rosacea). We tested the hypothesis that source–sink larval metapopulation dynamics describing the direction and frequency of larval dispersal according to an oceanographic model can help to explain empirical genetic data. We described modeled metapopulation dynamics using graph theory and employed empirical sequence data from a subset of 11 sites at two mitochondrial genes to verify the model predictions based on patterns of genetic diversity within sites and genetic structure between sites. We employed a population graph describing a network of genetic relationships among sites and contrasted it against modeled networks. While our results failed to explain genetic diversity within sites, they confirmed that ocean models summarized via graph and adjacency distances over modeled networks can explain seemingly chaotic patterns of genetic structure between sites. Empirical and modeled networks showed significant similarities in the clustering coefficients of each site and adjacency matrices between sites. Most of the connectivity patterns observed towards downstream sites (Sonora coast) were strictly asymmetric, while those between upstream sites (Baja and the Midriffs) were symmetric. The best-supported gene flow model and analyses of modularity of the modeled networks confirmed a pulse of larvae from the Baja Peninsula, across the Midriff Island region and towards the

  20. Asymmetric connectivity of spawning aggregations of a commercially important marine fish using a multidisciplinary approach.

    PubMed

    Munguia-Vega, Adrian; Jackson, Alexis; Marinone, Silvio Guido; Erisman, Brad; Moreno-Baez, Marcia; Girón-Nava, Alfredo; Pfister, Tad; Aburto-Oropeza, Octavio; Torre, Jorge

    2014-01-01

    Understanding patterns of larval dispersal is key in determining whether no-take marine reserves are self-sustaining, what will be protected inside reserves and where the benefits of reserves will be observed. We followed a multidisciplinary approach that merged detailed descriptions of fishing zones and spawning time at 17 sites distributed in the Midriff Island region of the Gulf of California with a biophysical oceanographic model that simulated larval transport at Pelagic Larval Duration (PLD) 14, 21 and 28 days for the most common and targeted predatory reef fish, (leopard grouper Mycteroperca rosacea). We tested the hypothesis that source-sink larval metapopulation dynamics describing the direction and frequency of larval dispersal according to an oceanographic model can help to explain empirical genetic data. We described modeled metapopulation dynamics using graph theory and employed empirical sequence data from a subset of 11 sites at two mitochondrial genes to verify the model predictions based on patterns of genetic diversity within sites and genetic structure between sites. We employed a population graph describing a network of genetic relationships among sites and contrasted it against modeled networks. While our results failed to explain genetic diversity within sites, they confirmed that ocean models summarized via graph and adjacency distances over modeled networks can explain seemingly chaotic patterns of genetic structure between sites. Empirical and modeled networks showed significant similarities in the clustering coefficients of each site and adjacency matrices between sites. Most of the connectivity patterns observed towards downstream sites (Sonora coast) were strictly asymmetric, while those between upstream sites (Baja and the Midriffs) were symmetric. The best-supported gene flow model and analyses of modularity of the modeled networks confirmed a pulse of larvae from the Baja Peninsula, across the Midriff Island region and towards the

  1. Seed dispersal by fishes in tropical and temperate fresh waters: The growing evidence

    NASA Astrophysics Data System (ADS)

    Horn, Michael H.; Correa, Sandra Bibiana; Parolin, Pia; Pollux, B. J. A.; Anderson, Jill T.; Lucas, Christine; Widmann, Peter; Tjiu, Albertus; Galetti, Mauro; Goulding, Michael

    2011-11-01

    Fruit-eating by fishes represents an ancient (perhaps Paleozoic) interaction increasingly regarded as important for seed dispersal (ichthyochory) in tropical and temperate ecosystems. Most of the more than 275 known frugivorous species belong to the mainly Neotropical Characiformes (pacus, piranhas) and Siluriformes (catfishes), but cypriniforms (carps, minnows) are more important in the Holarctic and Indomalayan regions. Frugivores are among the most abundant fishes in Neotropical floodplains where they eat the fruits of a wide variety of trees and shrubs. By consuming fruits, fishes gain access to rich sources of carbohydrates, lipids and proteins and act as either seed predators or seed dispersers. With their often high mobility, large size, and great longevity, fruit-eating fishes can play important roles as seed dispersers and exert strong influences on local plant-recruitment dynamics and regional biodiversity. Recent feeding experiments focused on seed traits after gut passage support the idea that fishes are major seed dispersers in floodplain and riparian forests. Overfishing, damming, deforestation and logging potentially diminish ichthyochory and require immediate attention to ameliorate their effects. Much exciting work remains in terms of fish and plant adaptations to ichthyochory, dispersal regimes involving fishes in different ecosystems, and increased use of nondestructive methods such as stomach lavage, stable isotopes, genetic analyses and radio transmitters to determine fish diets and movements.

  2. Low interbasin connectivity in a facultatively diadromous fish: evidence from genetics and otolith chemistry.

    PubMed

    Hughes, Jane M; Schmidt, Daniel J; Macdonald, Jed I; Huey, Joel A; Crook, David A

    2014-03-01

    Southern smelts (Retropinna spp.) in coastal rivers of Australia are facultatively diadromous, with populations potentially containing individuals with diadromous or wholly freshwater life histories. The presence of diadromous individuals is expected to reduce genetic structuring between river basins due to larval dispersal via the sea. We use otolith chemistry to distinguish between diadromous and nondiadromous life histories and population genetics to examine interbasin connectivity resulting from diadromy. Otolith strontium isotope ((87) Sr:(86) Sr) transects identified three main life history patterns: amphidromy, freshwater residency and estuarine/marine residency. Despite the potential for interbasin connectivity via larval mixing in the marine environment, we found unprecedented levels of genetic structure for an amphidromous species. Strong hierarchical structure along putative taxonomic boundaries was detected, along with highly structured populations within groups using microsatellites (FST  = 0.046-0.181), and mtDNA (ΦST  = 0.498-0.816). The presence of strong genetic subdivision, despite the fact that many individuals reside in saline water during their early life history, appears incongruous. However, analysis of multielemental signatures in the otolith cores of diadromous fish revealed strong discrimination between river basins, suggesting that diadromous fish spend their early lives within chemically distinct estuaries rather than the more homogenous marine environment, thus avoiding dispersal and maintaining genetic structure. PMID:24410817

  3. Fatal poisoning and other health hazards connected with industrial fishing

    PubMed Central

    Dalgaard, J. B.; Dencker, F.; Fallentin, B.; Hansen, P.; Kaempe, B.; Steensberg, J.; Wilhardt, P.

    1972-01-01

    Dalgaard, J. B., Dencker, F., Fallentin, B., Hansen, P., Kaempe, B., Steensberg, J., and Wilhardt, P. (1972).Brit. J. industr. Med.,29, 307-316. Fatal poisoning and other health hazards connected with industrial fishing. The literature about death and health problems related to work with fish for industrial use is reviewed. Three fatal cases and several instances of unconsciousness or cases of fainting are reported. An investigation was carried out into the composition of the air in the holds and forecastles of Danish industrial-fishing cutters on their arrival at port. The laboratory procedures are described, and the results are reported. In several instances the low concentrations of oxygen and/or high concentrations of carbon dioxide and hydrogen sulphide found were considered to be hazardous to life. The fatalities and sudden loss of consciousness in the reported cases are ascribed to these changes, hypoxia and hypercapnia being the most important causes. The risk of poisoning seems to be greatest during the landing of trash-fish and in fish-meal plants. Persons under the influence of alcohol may, for one reason or another, be particularly susceptible. The most important preventive measure is improvement of the quality of the raw material which would also reduce the nuisance from smell. Two safety belts with ropes should be provided in the vessels and close to the pits in the fish-meal plants. Fishermen should leave the vessel after arrival in port and not return until after unloading has been completed. During unloading and in the factories, effective mechanical ventilation is essential. Apparatus to monitor the concentrations of oxygen, carbon dioxide, hydrogen sulphide, and ammonia should be available in the fishing ports, and cases of accident, including mere `faintings', should be subjected to prompt medical and technical investigation. From the occupational medical aspect, fishermen are in a less satisfactory situation than workers on shore. An

  4. Sex biases in kin shoaling and dispersal in a cichlid fish.

    PubMed

    van Dongen, Wouter F D; Wagner, Richard H; Moodley, Yoshan; Schaedelin, Franziska C

    2014-12-01

    Animal dispersal is associated with diverse costs and benefits that vary among individuals based on phenotype and ecological conditions. For example, females may disperse when males benefit more from defending territories in familiar environments. Similarly, size differences in dispersal propensity may occur when dispersal costs are size-dependent. When individuals do disperse, they may adopt behavioral strategies that minimize dispersal costs. Dispersing fish, for example, may travel within shoals to reduce predation risks. Further, kin shoaling may augment inclusive fitness by reducing predation of relatives. However, studies are lacking on the role of kin shoaling in dispersal. We explored how sex and size influence dispersal and kin shoaling in the cichlid Neolamprologus caudopunctatus. We microsatellite genotyped over 900 individuals from two populations separated by a potential dispersal barrier, and documented patterns of population structure, migration and within-shoal relatedness. Genetic differentiation across the barrier was greater for smaller than larger fish, suggesting larger fish had dispersed longer distances. Females exhibited weaker genetic differentiation and 11 times higher migration rates than males, indicating longer-distance female-biased dispersal. Small females frequently shoaled with siblings, possibly offsetting dispersal costs associated with higher predation risks. In contrast, small males appeared to avoid kin shoaling, possibly to avoid local resource competition. In summary, long-distance dispersal in N. caudopunctatus appears to be female-biased, and kin-based shoaling by small females may represent a behavioral adaptation that reduces dispersal costs. Our study appears to be the first to provide evidence that sex differences in dispersal influence sex differences in kin shoaling. PMID:25231372

  5. Understanding the Spatial Scale of Genetic Connectivity at Sea: Unique Insights from a Land Fish and a Meta-Analysis.

    PubMed

    Cooke, Georgina M; Schlub, Timothy E; Sherwin, William B; Ord, Terry J

    2016-01-01

    Quantifying the spatial scale of population connectivity is important for understanding the evolutionary potential of ecologically divergent populations and for designing conservation strategies to preserve those populations. For marine organisms like fish, the spatial scale of connectivity is generally set by a pelagic larval phase. This has complicated past estimates of connectivity because detailed information on larval movements are difficult to obtain. Genetic approaches provide a tractable alternative and have the added benefit of estimating directly the reproductive isolation of populations. In this study, we leveraged empirical estimates of genetic differentiation among populations with simulations and a meta-analysis to provide a general estimate of the spatial scale of genetic connectivity in marine environments. We used neutral genetic markers to first quantify the genetic differentiation of ecologically-isolated adult populations of a land dwelling fish, the Pacific leaping blenny (Alticus arnoldorum), where marine larval dispersal is the only probable means of connectivity among populations. We then compared these estimates to simulations of a range of marine dispersal scenarios and to collated FST and distance data from the literature for marine fish across diverse spatial scales. We found genetic connectivity at sea was extensive among marine populations and in the case of A. arnoldorum, apparently little affected by the presence of ecological barriers. We estimated that ~5000 km (with broad confidence intervals ranging from 810-11,692 km) was the spatial scale at which evolutionarily meaningful barriers to gene flow start to occur at sea, although substantially shorter distances are also possible for some taxa. In general, however, such a large estimate of connectivity has important implications for the evolutionary and conservation potential of many marine fish communities. PMID:27195493

  6. Understanding the Spatial Scale of Genetic Connectivity at Sea: Unique Insights from a Land Fish and a Meta-Analysis

    PubMed Central

    Cooke, Georgina M.; Schlub, Timothy E.; Sherwin, William B.; Ord, Terry J.

    2016-01-01

    Quantifying the spatial scale of population connectivity is important for understanding the evolutionary potential of ecologically divergent populations and for designing conservation strategies to preserve those populations. For marine organisms like fish, the spatial scale of connectivity is generally set by a pelagic larval phase. This has complicated past estimates of connectivity because detailed information on larval movements are difficult to obtain. Genetic approaches provide a tractable alternative and have the added benefit of estimating directly the reproductive isolation of populations. In this study, we leveraged empirical estimates of genetic differentiation among populations with simulations and a meta-analysis to provide a general estimate of the spatial scale of genetic connectivity in marine environments. We used neutral genetic markers to first quantify the genetic differentiation of ecologically-isolated adult populations of a land dwelling fish, the Pacific leaping blenny (Alticus arnoldorum), where marine larval dispersal is the only probable means of connectivity among populations. We then compared these estimates to simulations of a range of marine dispersal scenarios and to collated FST and distance data from the literature for marine fish across diverse spatial scales. We found genetic connectivity at sea was extensive among marine populations and in the case of A. arnoldorum, apparently little affected by the presence of ecological barriers. We estimated that ~5000 km (with broad confidence intervals ranging from 810–11,692 km) was the spatial scale at which evolutionarily meaningful barriers to gene flow start to occur at sea, although substantially shorter distances are also possible for some taxa. In general, however, such a large estimate of connectivity has important implications for the evolutionary and conservation potential of many marine fish communities. PMID:27195493

  7. Gene flow by larval dispersal in the Antarctic notothenioid fish Gobionotothen gibberifrons.

    PubMed

    Matschiner, Michael; Hanel, Reinhold; Salzburger, Walter

    2009-06-01

    The diversification of the teleost suborder Notothenioidei (Perciformes) in Antarctic waters provides one of the most striking examples of a marine adaptive radiation. Along with a number of adaptations to the cold environment, such as the evolution of antifreeze glycoproteins, notothenioids diversified into eight families and at least 130 species. Here, we investigate the genetic population structure of the humped rockcod (Gobionotothen gibberifrons), a benthic notothenioid fish. Six populations were sampled at different locations around the Scotia Sea, comprising a large part of the species' distribution range (N = 165). Our analyses based on mitochondrial DNA sequence data (352 bp) and eight microsatellite markers reveal a lack of genetic structuring over large geographic distances (Phi(ST) < or = 0.058, F(ST) < or = 0.005, P values nonsignificant). In order to test whether this was due to passive larval dispersal, we used GPS-tracked drifter trajectories, which approximate movement of passive surface particles with ocean currents. The drifter data indicate that the Antarctic Circumpolar Current (ACC) connects the sampling locations in one direction only (west-east), and that passive transport is possible within the 4-month larval period of G. gibberifrons. Indeed, when applying the isolation-with-migration model in IMA, strong unidirectional west-east migration rates are detected in the humped rockcod. This leads us to conclude that, in G. gibberifrons, genetic differentiation is prevented by gene flow via larval dispersal with the ACC. PMID:19457182

  8. Larval dispersal and movement patterns of coral reef fishes, and implications for marine reserve network design.

    PubMed

    Green, Alison L; Maypa, Aileen P; Almany, Glenn R; Rhodes, Kevin L; Weeks, Rebecca; Abesamis, Rene A; Gleason, Mary G; Mumby, Peter J; White, Alan T

    2015-11-01

    Well-designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1-0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5-3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3-10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds

  9. Spatial and temporal patterns of larval dispersal in a coral-reef fish metapopulation: evidence of variable reproductive success.

    PubMed

    Pusack, Timothy J; Christie, Mark R; Johnson, Darren W; Stallings, Christopher D; Hixon, Mark A

    2014-07-01

    Many marine organisms can be transported hundreds of kilometres during their pelagic larval stage, yet little is known about spatial and temporal patterns of larval dispersal. Although traditional population-genetic tools can be applied to infer movement of larvae on an evolutionary timescale, large effective population sizes and high rates of gene flow present serious challenges to documenting dispersal patterns over shorter, ecologically relevant, timescales. Here, we address these challenges by combining direct parentage analysis and indirect genetic analyses over a 4-year period to document spatial and temporal patterns of larval dispersal in a common coral-reef fish: the bicolour damselfish (Stegastes partitus). At four island locations surrounding Exuma Sound, Bahamas, including a long-established marine reserve, we collected 3278 individuals and genotyped them at 10 microsatellite loci. Using Bayesian parentage analysis, we identified eight parent-offspring pairs, thereby directly documenting dispersal distances ranging from 0 km (i.e., self-recruitment) to 129 km (i.e., larval connectivity). Despite documenting substantial dispersal and gene flow between islands, we observed more self-recruitment events than expected if the larvae were drawn from a common, well-mixed pool (i.e., a completely open population). Additionally, we detected both spatial and temporal variation in signatures of sweepstakes and Wahlund effects. The high variance in reproductive success (i.e., 'sweepstakes') we observed may be influenced by seasonal mesoscale gyres present in the Exuma Sound, which play a prominent role in shaping local oceanographic patterns. This study documents the complex nature of larval dispersal in a coral-reef fish, and highlights the importance of sampling multiple cohorts and coupling both direct and indirect genetic methods in order disentangle patterns of dispersal, gene flow and variable reproductive success. PMID:24917250

  10. Subtle genetic structure reveals restricted connectivity among populations of a coral reef fish inhabiting remote atolls

    PubMed Central

    Underwood, Jim N; Travers, Michael J; Gilmour, James P

    2012-01-01

    We utilized a spatial and temporal analyses of genetic structure, supplemented with ecological and oceanographic analysis, to assess patterns of population connectivity in a coral reef fish Chromis margaritifer among the unique and remote atolls in the eastern Indian Ocean. A subtle, but significant genetic discontinuity at 10 microsatellite DNA loci was detected between atoll systems corresponding with a low (≤ 1%) probability of advection across the hundreds of kilometers of open ocean that separates them. Thus, although genetic connections between systems are likely maintained by occasional long-distance dispersal of C. margaritifer larvae, ecological population connectivity at this spatial scale appears to be restricted. Further, within one of these atoll systems, significant spatial differentiation among samples was accompanied by a lack of temporal pairwise differentiation between recruit and adult samples, indicating that restrictions to connectivity also occur at a local scale (tens of kilometers). In contrast, a signal of panmixia was detected at the other atoll system studied. Lastly, greater relatedness and reduced genetic diversity within recruit samples was associated with relatively large differences among them, indicating the presence of sweepstakes reproduction whereby a small proportion of adults contributes to recruitment in the next generation. These results are congruent with earlier work on hard corals, suggesting that local production of larvae drives population replenishment in these atoll systems for a range of coral reef species. PMID:22822442

  11. Subtle genetic structure reveals restricted connectivity among populations of a coral reef fish inhabiting remote atolls.

    PubMed

    Underwood, Jim N; Travers, Michael J; Gilmour, James P

    2012-03-01

    We utilized a spatial and temporal analyses of genetic structure, supplemented with ecological and oceanographic analysis, to assess patterns of population connectivity in a coral reef fish Chromis margaritifer among the unique and remote atolls in the eastern Indian Ocean. A subtle, but significant genetic discontinuity at 10 microsatellite DNA loci was detected between atoll systems corresponding with a low (≤ 1%) probability of advection across the hundreds of kilometers of open ocean that separates them. Thus, although genetic connections between systems are likely maintained by occasional long-distance dispersal of C. margaritifer larvae, ecological population connectivity at this spatial scale appears to be restricted. Further, within one of these atoll systems, significant spatial differentiation among samples was accompanied by a lack of temporal pairwise differentiation between recruit and adult samples, indicating that restrictions to connectivity also occur at a local scale (tens of kilometers). In contrast, a signal of panmixia was detected at the other atoll system studied. Lastly, greater relatedness and reduced genetic diversity within recruit samples was associated with relatively large differences among them, indicating the presence of sweepstakes reproduction whereby a small proportion of adults contributes to recruitment in the next generation. These results are congruent with earlier work on hard corals, suggesting that local production of larvae drives population replenishment in these atoll systems for a range of coral reef species. PMID:22822442

  12. Stability and generalization in seed dispersal networks: a case study of frugivorous fish in Neotropical wetlands.

    PubMed

    Correa, Sandra Bibiana; Arujo, Joisiane K; Penha, Jerry; Nunes da Cunha, Catia; Bobier, Karen E; Anderson, Jill T

    2016-08-31

    When species within guilds perform similar ecological roles, functional redundancy can buffer ecosystems against species loss. Using data on the frequency of interactions between fish and fruit, we assessed whether co-occurring frugivores provide redundant seed dispersal services in three species-rich Neotropical wetlands. Our study revealed that frugivorous fishes have generalized diets; however, large-bodied fishes had greater seed dispersal breadth than small species, in some cases, providing seed dispersal services not achieved by smaller fish species. As overfishing disproportionately affects big fishes, the extirpation of these species could cause larger secondary extinctions of plant species than the loss of small specialist frugivores. To evaluate the consequences of frugivore specialization for network stability, we extracted data from 39 published seed dispersal networks of frugivorous birds, mammals and fish (our networks) across ecosystems. Our analysis of interaction frequencies revealed low frugivore specialization and lower nestedness than analyses based on binary data (presence-absence of interactions). In that case, ecosystems may be resilient to loss of any given frugivore. However, robustness to frugivore extinction declines with specialization, such that networks composed primarily of specialist frugivores are highly susceptible to the loss of generalists. In contrast with analyses of binary data, recently developed algorithms capable of modelling interaction strengths provide opportunities to enhance our understanding of complex ecological networks by accounting for heterogeneity of frugivore-fruit interactions. PMID:27581879

  13. Connectivity, fish communities, and human impacts: An integrated river systems perspective

    EPA Science Inventory

    The role of connectivity between aquatic habitats in sustaining productive and healthy fish communities has become a key conservation concern. Changes in connectivity due to anthropogenic impacts can alter fish communities and put particular species at risk. In order to underst...

  14. A non-destructive sampling protocol for field studies of seed dispersal by fishes.

    PubMed

    Correa, S B; Anderson, J T

    2016-05-01

    This paper presents a standardized protocol for the non-lethal capture of fishes, sampling of stomach contents and quantification of seed dispersal efficiency by frugivorous fishes. Neotropical pacu Piaractus mesopotamicus individuals were collected with fruit-baited hooks. The diets of 110 fish were sampled using a lavage method, which retrieved >90% of stomach contents of both juveniles and adults and allowed individuals to recover within 5 min of treatment. The proportional volume of six food categories was similar for stomachs and whole digestive tracts retrieved by dissection. Fruit pulp was proportionally lower in the stomach. The abundance and species richness of intact seeds increased with fish size independent of whether only stomachs or whole digestive tracts were analysed. The analysis of stomach contents accounted for 62·5% of the total species richness of seeds dispersed by P. mesopotamicus and 96% of common seeds (seed species retrieved from more than one fish). Germination trials revealed that seed viability was similar for seeds collected from the stomach via lavage and seeds that passed through the entire digestive tract. Therefore, stomach contents provide an unbiased representation of the dietary patterns and seed dispersal of frugivorous fishes. PMID:27097831

  15. Larval dispersal underlies demographically important inter-system connectivity in a Great Lakes yellow perch (Perca flavescens) population

    USGS Publications Warehouse

    Brodnik, Reed M.; Fraker, Michael E.; Anderson, Eric J.; Carreon-Martinez, Lucia; DeVanna, Kristen M.; Heath, Dan D.; Reichert, Julie M.; Roseman, Edward F.; Ludsin, Stuart A.

    2016-01-01

    Ability to quantify connectivity among spawning subpopulations and their relative contribution of recruits to the broader population is a critical fisheries management need. By combining microsatellite and age information from larval yellow perch (Perca flavescens) collected in the Lake St. Clair – Detroit River system (SC-DRS) and western Lake Erie with a hydrodynamic backtracking approach, we quantified subpopulation structure, connectivity, and contributions of recruits to the juvenile stage in western Lake Erie during 2006-2007. After finding weak (yet stable) genetic structure between the SC-DRS and two western Lake Erie subpopulations, microsatellites also revealed measurable recruitment of SC-DRS larvae to the juvenile stage in western Lake Erie (17-21% during 2006-2007). Consideration of pre-collection larval dispersal trajectories, using hydrodynamic backtracking, increased estimated contributions to 65% in 2006 and 57% in 2007. Our findings highlight the value of complementing subpopulation discrimination methods with hydrodynamic predictions of larval dispersal by revealing the SC-DRS as a source of recruits to western Lake Erie and also showing that connectivity through larval dispersal can affect the structure and dynamics of large-lake fish populations.

  16. Fish with Chips: Tracking Reef Fish Movements to Evaluate Size and Connectivity of Caribbean Marine Protected Areas

    PubMed Central

    Pittman, Simon J.; Monaco, Mark E.; Friedlander, Alan M.; Legare, Bryan; Nemeth, Richard S.; Kendall, Matthew S.; Poti, Matthew; Clark, Randall D.; Wedding, Lisa M.; Caldow, Chris

    2014-01-01

    Coral reefs and associated fish populations have experienced rapid decline in the Caribbean region and marine protected areas (MPAs) have been widely implemented to address this decline. The performance of no-take MPAs (i.e., marine reserves) for protecting and rebuilding fish populations is influenced by the movement of animals within and across their boundaries. Very little is known about Caribbean reef fish movements creating a critical knowledge gap that can impede effective MPA design, performance and evaluation. Using miniature implanted acoustic transmitters and a fixed acoustic receiver array, we address three key questions: How far can reef fish move? Does connectivity exist between adjacent MPAs? Does existing MPA size match the spatial scale of reef fish movements? We show that many reef fishes are capable of traveling far greater distances and in shorter duration than was previously known. Across the Puerto Rican Shelf, more than half of our 163 tagged fish (18 species of 10 families) moved distances greater than 1 km with three fish moving more than 10 km in a single day and a quarter spending time outside of MPAs. We provide direct evidence of ecological connectivity across a network of MPAs, including estimated movements of more than 40 km connecting a nearshore MPA with a shelf-edge spawning aggregation. Most tagged fish showed high fidelity to MPAs, but also spent time outside MPAs, potentially contributing to spillover. Three-quarters of our fish were capable of traveling distances that would take them beyond the protection offered by at least 40–64% of the existing eastern Caribbean MPAs. We recommend that key species movement patterns be used to inform and evaluate MPA functionality and design, particularly size and shape. A re-scaling of our perception of Caribbean reef fish mobility and habitat use is imperative, with important implications for ecology and management effectiveness. PMID:24797815

  17. Fish with chips: tracking reef fish movements to evaluate size and connectivity of Caribbean marine protected areas.

    PubMed

    Pittman, Simon J; Monaco, Mark E; Friedlander, Alan M; Legare, Bryan; Nemeth, Richard S; Kendall, Matthew S; Poti, Matthew; Clark, Randall D; Wedding, Lisa M; Caldow, Chris

    2014-01-01

    Coral reefs and associated fish populations have experienced rapid decline in the Caribbean region and marine protected areas (MPAs) have been widely implemented to address this decline. The performance of no-take MPAs (i.e., marine reserves) for protecting and rebuilding fish populations is influenced by the movement of animals within and across their boundaries. Very little is known about Caribbean reef fish movements creating a critical knowledge gap that can impede effective MPA design, performance and evaluation. Using miniature implanted acoustic transmitters and a fixed acoustic receiver array, we address three key questions: How far can reef fish move? Does connectivity exist between adjacent MPAs? Does existing MPA size match the spatial scale of reef fish movements? We show that many reef fishes are capable of traveling far greater distances and in shorter duration than was previously known. Across the Puerto Rican Shelf, more than half of our 163 tagged fish (18 species of 10 families) moved distances greater than 1 km with three fish moving more than 10 km in a single day and a quarter spending time outside of MPAs. We provide direct evidence of ecological connectivity across a network of MPAs, including estimated movements of more than 40 km connecting a nearshore MPA with a shelf-edge spawning aggregation. Most tagged fish showed high fidelity to MPAs, but also spent time outside MPAs, potentially contributing to spillover. Three-quarters of our fish were capable of traveling distances that would take them beyond the protection offered by at least 40-64% of the existing eastern Caribbean MPAs. We recommend that key species movement patterns be used to inform and evaluate MPA functionality and design, particularly size and shape. A re-scaling of our perception of Caribbean reef fish mobility and habitat use is imperative, with important implications for ecology and management effectiveness. PMID:24797815

  18. Comparison of fish assemblages in two disjoined segments of an oxbow lake in relation to connectivity

    USGS Publications Warehouse

    Dembkowski, Daniel J.; Miranda, Leandro E.

    2011-01-01

    Disconnection between adjacent habitat patches is one of the most notable factors contributing to the decreased biotic integrity of global ecosystems. Connectivity is especially threatened in river–floodplain ecosystems in which channel modifications have disrupted the lateral links between the main river channel and floodplain lakes. In this study, we examined the interaction between the interconnectedness of floodplain lakes and main river channels and fish assemblage descriptors. Fish assemblages in two segments of an oxbow lake, one connected to and the other isolated from the Yazoo River, Mississippi, were estimated with daytime boat electrofishing during 2007–2010. The frequency of connection for the connected segment ranged from zero to seven individual events per year (mean, ∼2). The timing of most connection events reflected regional precipitation patterns. Greater species richness, diversity, and evenness were observed in the connected segment. Additionally, the connected segment had a greater abundance of piscivores and periodic life history strategists. All fishes collected solely in the connected segment were typically riverine in nature, whereas fishes collected only in the disconnected segment were more lacustrine adapted. These results suggest that periodic connection and the associated habitat heterogeneity that it provides are important for maintaining fish species richness and diversity in large-river floodplain lakes. We suggest that maintenance or restoration of connection be an integral part of fluvial ecosystem management plans.

  19. Local scale connectivity in the cave-dwelling brooding fish Apogon imberbis

    NASA Astrophysics Data System (ADS)

    Muths, Delphine; Rastorgueff, Pierre-Alexandre; Selva, Marjorie; Chevaldonné, Pierre

    2015-01-01

    A lower degree of population connectivity is generally expected for species living in a naturally fragmented habitat than for species living in a continuum of suitable environment. Due to clear-cut environmental conditions with the surrounding littoral zone, underwater marine caves of the Mediterranean Sea constitute a good model to explore the effect of habitat discontinuity on the population structure of their inhabitants. With this goal, the genetic population structure of Apogon imberbis, a mouth-brooding teleost, was explored using the mitochondrial cytochrome b gene and 7 nuclear microsatellite loci from 164 fishes sampled at the micro-scale (ca. 40 km) of the Marseille area (Bay of Marseille and Calanques coast, in NW Mediterranean). Both marker types indicated a low level of genetic structure within the studied area. We propose that each suitable crack and cavity is used as a stepping-stone habitat between disconnected large cave-habitats. This, together with larval dispersal, ensures enough gene flow between caves to homogenize the genetic pattern at microscale while isolation by distance and by open waters could explain the small structure observed. The present study indicates that the effect of natural fragmentation in connectivity disruption can largely be counter-balanced by life history traits and overlooked details in habitat preferences.

  20. Surface water connectivity drives richness and composition of Arctic lake fish assemblages

    USGS Publications Warehouse

    Laske, Sarah M.; Haynes, Trevor B.; Rosenberger, Amanda E.; Koch, Joshua C.; Wipfli, Mark S.; Whitman, Matthew; Zimmerman, Christian E.

    2016-01-01

    This work provides useful baseline information on the processes that drive the relations between patch connectivity and fish species richness and assemblage composition. The environmental processes that organise fish assemblages in Arctic lakes are likely to change in a warming climate.

  1. Passive advection-dispersion in networks of pipes: Effect of connectivity and relationship to permeability

    NASA Astrophysics Data System (ADS)

    Bernabé, Y.; Wang, Y.; Qi, T.; Li, M.

    2016-02-01

    The main purpose of this work is to investigate the relationship between passive advection-dispersion and permeability in porous materials presumed to be statistically homogeneous at scales larger than the pore scale but smaller than the reservoir scale. We simulated fluid flow through pipe network realizations with different pipe radius distributions and different levels of connectivity. The flow simulations used periodic boundary conditions, allowing monitoring of the advective motion of solute particles in a large periodic array of identical network realizations. In order to simulate dispersion, we assumed that the solute particles obeyed Taylor dispersion in individual pipes. When a particle entered a pipe, a residence time consistent with local Taylor dispersion was randomly assigned to it. When exiting the pipe, the particle randomly proceeded into one of the pipes connected to the original one according to probabilities proportional to the outgoing volumetric flow in each pipe. For each simulation we tracked the motion of at least 6000 solute particles. The mean fluid velocity was 10-3 ms-1, and the distance traveled was on the order of 10 m. Macroscopic dispersion was quantified using the method of moments. Despite differences arising from using different types of lattices (simple cubic, body-centered cubic, and face-centered cubic), a number of general observations were made. Longitudinal dispersion was at least 1 order of magnitude greater than transverse dispersion, and both strongly increased with decreasing pore connectivity and/or pore size variability. In conditions of variable hydraulic radius and fixed pore connectivity and pore size variability, the simulated dispersivities increased as power laws of the hydraulic radius and, consequently, of permeability, in agreement with previously published experimental results. Based on these observations, we were able to resolve some of the complexity of the relationship between dispersivity and permeability.

  2. Marine population connectivity: reconciling large-scale dispersal and high self-retention.

    PubMed

    Nickols, Kerry J; White, J Wilson; Largier, John L; Gaylord, Brian

    2015-02-01

    Predicting connectivity patterns in systems with fluid transport requires descriptions of the spatial distribution of propagules. In contrast to research on terrestrial seed dispersal, where much attention has focused on localized physical factors affecting dispersal, studies of oceanic propagule dispersal have often emphasized the role of large-scale factors. We link these two perspectives by exploring how propagule dispersal in the ocean is influenced by the "coastal boundary layer" (CBL), a region of reduced velocities near the shoreline that might substantially modify local-scale dispersal. We used a simple simulation model to demonstrate that accounting for the CBL markedly alters transport distances, the widths of dispersal distributions, and the fraction of larvae retained near their sites of origin (self-retention). Median dispersal distances were up to 59% shorter in simulations with a CBL than in those without. Self-retention of larvae increased by up to 3 orders of magnitude in the presence of CBLs, but only minor changes arose in the long-distance tails of the distributions, resulting in asymmetric, non-Gaussian kernels analogous to those quantified for terrestrial seed dispersal. Because successfully settling larvae are commonly those that remain close to shore and interact with the CBL, ignoring this pervasive oceanographic feature will substantially alter predictions of population self-persistence, estimates of connectivity, and outcomes of metapopulation analyses. PMID:25616139

  3. Does stability in local community composition depend on temporal variation in rates of dispersal and connectivity?

    NASA Astrophysics Data System (ADS)

    Valanko, Sebastian; Norkko, Joanna; Norkko, Alf

    2015-04-01

    In ecology understanding variation in connectivity is central for how biodiversity is maintained. Field studies on dispersal and temporal dynamics in community regulating processes are, however, rare. We test the short-term temporal stability in community composition in a soft-sediment benthic community by determining among-sampling interval similarity in community composition. We relate stability to in situ measures of connectivity (wind, wave, current energy) and rates of dispersal (quantified in different trap types). Waves were an important predictor of when local community taxa are most likely to disperse in different trap-types, suggesting that wave energy is important for connectivity in a region. Community composition at the site was variable and changed stochastically over time. We found changes in community composition (occurrence, abundance, dominance) to be greater at times when connectivity and rates of dispersal were low. In response to periods of lower connectedness dominant taxa in the local community only exhibited change in their relative abundance. In contrast, locally less abundant taxa varied in both their presence, as well as in relative abundance. Constancy in connectivity and rates of dispersal promotes community stability and persistence, suggesting that local community composition will be impacted by changes in the spatial extent over which immigration and emigration operates in the region. Few empirical studies have actually measured dispersal directly in a multi-species context to demonstrate the role it plays in maintaining local community structure. Even though our study does not evaluate coexistence over demographic time scales, it importantly demonstrates that dispersal is not only important in initial recruitment or following a disturbance, but also key in maintaining local community composition.

  4. Connectivity controls on the late Miocene eastern Mediterranean fish fauna

    NASA Astrophysics Data System (ADS)

    Agiadi, Konstantina; Antonarakou, Assimina; Kontakiotis, George; Kafousia, Nefeli; Moissette, Pierre; Cornée, Jean-Jacques; Manoutsoglou, Emmanouil; Karakitsios, Vasileios

    2016-06-01

    Environmental change significantly affects the production of fish resources and their dependent societies. The paleontological record offers unique insight into the effects of long-term paleoenvironmental variability on the fish species' distributions and abundances. In the present study, we investigate the late Miocene (7.5-6.5 Ma) fish assemblages of the Potamida section in western Crete (eastern Mediterranean). The determined fish taxa are examined in a paleobiogeographic context, with regard to their geographic and stratigraphic distribution from the early Miocene (~13 Ma) through today. In addition, present-day ecological data are used to reconstruct the paleoenvironmental conditions in the study area. Planktonic foraminifer biostratigraphy significantly improves the earlier dating of the studied sequence. The late Miocene fish fauna of Potamida includes 35 taxa (seven in open nomenclature) from 13 teleost families. The eastern Mediterranean biostratigraphic and geographic distribution of 32 taxa is significantly expanded into the Tortonian, whereas 13 species are recorded for the first time from the Messinian. Four stages are distinguished in the area's paleoenvironmental evolution. (1) The Potamida area was an open marine environment with depths exceeding 150 m between ~7.5-7.45 Ma. (2) Between 7.45-7.36 Ma, the results suggest depths between 300-400 m. (3) The depositional depth increases between 7.36-7.28 Ma to 400-550 m. (4) Later on, approximately between 6.8-6.6 Ma, the depth is again estimated around 100-150 m.

  5. Fish assemblages, connectivity, and habitat rehabilitation in a diked Great Lakes coastal wetland complex

    USGS Publications Warehouse

    Kowalski, Kurt P.; Wiley, Michael J.; Wilcox, Douglas A.

    2014-01-01

    Fish and plant assemblages in the highly modified Crane Creek coastal wetland complex of Lake Erie were sampled to characterize their spatial and seasonal patterns and to examine the implications of the hydrologic connection of diked wetland units to Lake Erie. Fyke netting captured 52 species and an abundance of fish in the Lake Erie–connected wetlands, but fewer than half of those species and much lower numbers and total masses of fish were captured in diked wetland units. Although all wetland units were immediately adjacent to Lake Erie, there were also pronounced differences in water quality and wetland vegetation between the hydrologically isolated and lake-connected wetlands. Large seasonal variations in fish assemblage composition and biomass were observed in connected wetland units but not in disconnected units. Reestablishment of hydrologic connectivity in diked wetland units would allow coastal Lake Erie fish to use these vegetated habitats seasonally, although connectivity does appear to pose some risks, such as the expansion of invasive plants and localized reductions in water quality. Periodic isolation and drawdown of the diked units could still be used to mimic intermediate levels of disturbance and manage invasive wetland vegetation.

  6. Numerical modelling of organic waste dispersion from fjord located fish farms

    NASA Astrophysics Data System (ADS)

    Ali, Alfatih; Thiem, Øyvind; Berntsen, Jarle

    2011-07-01

    In this study, a three-dimensional particle tracking model coupled to a terrain following ocean model is used to investigate the dispersion and the deposition of fish farm particulate matter (uneaten food and fish faeces) on the seabed due to tidal currents. The particle tracking model uses the computed local flow field for advection of the particles and random movement to simulate the turbulent diffusion. Each particle is given a settling velocity which may be drawn from a probability distribution according to settling velocity measurements of faecal and feed pellets. The results show that the maximum concentration of organic waste for fast sinking particles is found under the fish cage and continue monotonically decreasing away from the cage area. The maximum can split into two maximum peaks located at both sides of the centre of the fish cage area in the current direction. This process depends on the sinking time (time needed for a particle to settle at the bottom), the tidal velocity and the fish cage size. If the sinking time is close to a multiple of the tidal period, the maximum concentration point will be under the fish cage irrespective of the tide strength. This is due to the nature of the tidal current first propagating the particles away and then bringing them back when the tide reverses. Increasing the cage size increases the likelihood for a maximum waste accumulation beneath the fish farm, and larger farms usually means larger biomasses which can make the local pollution even more severe. The model is validated by using an analytical model which uses an exact harmonic representation of the tidal current, and the results show an excellent agreement. This study shows that the coupled ocean and particle model can be used in more realistic applications to help estimating the local environmental impact due to fish farms.

  7. Assemblage patterns of fish functional groups relative to habitat connectivity and conditions in floodplain lakes

    USGS Publications Warehouse

    Miyazono, S.; Aycock, J.N.; Miranda, L.E.; Tietjen, T.E.

    2010-01-01

    We evaluated the influences of habitat connectivity and local environmental factors on the distribution and abundance patterns of fish functional groups in 17 floodplain lakes in the Yazoo River Basin, USA. The results of univariate and multivariate analyses showed that species-environmental relationships varied with the functional groups. Species richness and assemblage structure of periodic strategists showed strong and positive correlations with habitat connectivity. Densities of most equilibrium and opportunistic strategists decreased with habitat connectivity. Densities of certain equilibrium and opportunistic strategists increased with turbidity. Forested wetlands around the lakes were positively related to the densities of periodic and equilibrium strategists. These results suggest that decreases in habitat connectivity, forested wetland buffers and water quality resulting from environmental manipulations may cause local extinction of certain fish taxa and accelerate the dominance of tolerant fishes in floodplain lakes. ?? 2010 John Wiley & Sons A/S.

  8. BOLTS: a BiOphysical Larval Tracking System for Measuring Dispersal Characteristics and Marine Population Connectivity

    NASA Astrophysics Data System (ADS)

    Paris, C. B.; Srinivasan, A.; Kourafalou, V.; Sponaugle, S.; Cowen, R. K.

    2008-12-01

    While metapopulation research with hypothetical dispersal matrices has shown how the scales of larval dispersal, transport processes, local recruitment, and temporal and spatial variability in dispersal influence population persistence, the pattern of demographic connectivity produced by larval dispersal is still a key uncertainty. To address this problem, a coupled bio-physical model has been developed that quantifies the degree of connectivity between populations. Such spatially explicit models, forced by dynamic currents coupled to a realistic seascape and life history traits, produce dispersal kernels for a range of scales over which dispersal is practically unquantifiable by current empirical methods. The BiOphysical Larval Tracking System (BOLTS) presented here allows a Lagrangian stochastic individual-based model (IBM) to be coupled via OPENDAP framework to any 3-dimensional fields of circulation models including to domains of various resolutions through 'Lagrangian nesting'. We demonstrate the capabilities of the software in measuring the characteristics of dispersal and evaluating the variability of larval connectivity through two examples at different scales: 1) Caribbean-scale simulations of BOLTS using the large scale (resolution ~7 km) Hybrid Coordinate Ocean Model (HYCOM) from the Global Data Assimilative Experiment (GODAE) provide us with expected connectivity patterns of a reef building coral. By seeding the model with a large number of active particles, it is possible to assemble dispersal kernels and migration matrices from the start (spawning) and the end point (settlement) of individual particle trajectories. Any single run is a stochastic realization of a probabilistic process, thus the full probability density function (pdf) of the kernel requires averaging over many dispersal events. The model output is further corroborated with empirical measures of gene flow among coral colonies around the Caribbean. 2) Coastal-scale simulations of BOLTS

  9. Observations of migrant exchange and mixing in a coral reef fish metapopulation link scales of marine population connectivity.

    PubMed

    Horne, John B; van Herwerden, Lynne; Abellana, Sheena; McIlwain, Jennifer L

    2013-01-01

    Much progress has been made toward understanding marine metapopulation dynamics, largely because of multilocus microsatellite surveys able to connect related individuals within the metapopulation. However, most studies are focused on small spatial scales, tens of kilometers, while demographic exchange at larger spatial scales remains poorly documented. Additionally, many small-scale demographic studies conflict with broad-scale phylogeographic patterns concerning levels of marine population connectivity, highlighting a need for data on more intermediate scales. Here, we investigated demographic recruitment processes of a commercially important coral reef fish, the bluespine unicornfish (Naso unicornis) using a suite of mitochondrial DNA (mtDNA) and microsatellite markers. Sampling for this study ranged across the southern Marianas Islands, a linear distance of 250 km and included 386 newly settled postlarval recruits. In contrast with other studies, we report that cohorts of recruits were genetically homogeneous in space and time, with no evidence of temporally stochastic sweepstakes reproduction. The genetic diversity of recruits was high and commensurate with that of the adult population. In addition, there is substantial evidence that 2 recruits, separated by 250 km, were full siblings. This is the largest direct observation of dispersal to date for a coral reef fish. All indications suggest that subpopulations of N. unicornis experience high levels of demographic migrant exchange and metapopulation mixing on a spatial scale of hundreds of kilometers, consistent with high levels of broad-scale genetic connectivity previously reported in this species. PMID:23580757

  10. Using stable isotope systematics and trace metals to constrain the dispersion of fish farm pollution

    NASA Astrophysics Data System (ADS)

    Torchinsky, A.; Shiel, A. E.; Price, M.; Weis, D. A.

    2010-12-01

    Fish farming is a growing industry of great economic importance to coastal communities. Unfortunately, open-net fish farming is associated with the release of organic and metal pollution, which has the potential to adversely affect the coastal marine environment. The dispersion of fish farm pollution and its environmental impact are not well understood/quantified. Pollutants released by fish farms include organic products such as uneaten feed pellets and fish feces, as well as chemicals and pharmaceuticals, all of which may enter marine ecosystems. In this study, we took advantage of bioaccumulation in passive suspension feeding Manila Clams collected at varying distances from an open-net salmon farm located in the Discovery Islands of British Columbia. Measurements of stable C and N isotopes, as well as trace metal concentrations, in the clams were used to investigate the spread of pollutants by detecting the presence of fish farm waste in the clams’ diet. Lead isotopic measurements were used to identify other significant anthropogenic pollution sources, which may impact the study area. Clams located within the areal extent of waste discharged by a fish farm are expected to exhibit anomalous light stable isotope ratios and metal concentrations, reflecting the presence of pollutants accumulated directly from seawater and from their diet. Clams were collected in the Discovery Islands from three sites in the Octopus Islands, located 850 m, 2100 m and 3000 m north of the Cyrus Rocks salmon farm (near Quadra Island) and from a reference site on Penn Island. Light stable isotope ratios (δN = ~10‰, with little variation between sites, and δC from -14.5 to -17.3‰) of the clams suggest that the most distal site (i.e., 3000 m away) is most impacted by organic fish farm waste (i.e., food pellets and feces) and that contributions of organic waste actually decrease closer to the farm. Not surprisingly, the smallest contribution of organic waste was detected in clams

  11. Ecosystem connectivity: anadromous fish migration linked to freshwater amphipods

    NASA Astrophysics Data System (ADS)

    Macavoy, S. E.; Fogel, M. L.; Fong, D.; Hanson, N.

    2009-12-01

    Anadromous fish migrate to coastal streams to spawn each spring and may transfer marine derived nutrients to oligotrophic tidal freshwater. River herring (Alosa sp) are the dominant anadromous genus in Virginia, USA. This study investigates whether marine nutrients derived by the spawning Alosa were incorporated into benthic invertebrates by using the stable isotopes of carbon and nitrogen. Spawning Alosa had higher δ13C and δ15N than resident freshwater omnivorous fishes (-18.5 and 13.9‰ versus -25.7 and 11.8‰). In a tidal stream supporting abundant spawning Alosa, significant 13C and 15N enrichment was observed among stream invertebrates, particularly in the amphipod Gammarus fasciatus, coincident with the Alosa spawning migration. Among G. fasciatus, δ13C increased from -28.5 to -26.0‰ between early and late April then fell to -28.1‰ in early June. A similar trend was observed in mayflies (Heptageniidae). In an adjacent tidal stream that did not support spawning Alosa, enrichment among invertebrates was not observed. Particulate organic matter and sediments from both streams remained 13C and 15N depleted during the Alosa spawning run (between -29 and -28‰, 0.5 and 3.0‰ respectively), suggesting that marine material was not present. Although marine organic material may have been incorporated into stream invertebrates, it did not become a substantial component of other ecosystem components measured.

  12. The influence of oceanographic fronts and early-life-history traits on connectivity among littoral fish species

    PubMed Central

    Galarza, Juan A.; Carreras-Carbonell, Josep; Macpherson, Enrique; Pascual, Marta; Roques, Severine; Turner, George F.; Rico, Ciro

    2009-01-01

    The spatial distribution of neutral genetic diversity is mainly influenced by barriers to dispersal. The nature of such barriers varies according to the dispersal means and capabilities of the organisms concerned. Although these barriers are often obvious on land, in the ocean they can be more difficult to identify. Determining the relative influence of physical and biotic factors on genetic connectivity remains a major challenge for marine ecologists. Here, we compare gene flow patterns of 7 littoral fish species from 6 families with a range of early-life-history traits sampled at the same geographic locations across common environmental discontinuities in the form of oceanic fronts in the Western Mediterranean. We show that these fronts represent major barriers to gene flow and have a strong influence on the population genetic structure of some fish species. We also found no significant relation between the early-life-history traits most commonly investigated (egg type, pelagic larval duration, and inshore-offshore spawning) and gene flow patterns, suggesting that other life-history factors should deserve attention. The fronts analyzed and the underlying physical mechanisms are not site-specific but common among the oceans, suggesting the generality of our findings. PMID:19164518

  13. Ecological traits influencing range expansion across large oceanic dispersal barriers: insights from tropical Atlantic reef fishes.

    PubMed

    Luiz, Osmar J; Madin, Joshua S; Robertson, D Ross; Rocha, Luiz A; Wirtz, Peter; Floeter, Sergio R

    2012-03-01

    How do biogeographically different provinces arise in response to oceanic barriers to dispersal? Here, we analyse how traits related to the pelagic dispersal and adult biology of 985 tropical reef fish species correlate with their establishing populations on both sides of two Atlantic marine barriers: the Mid-Atlantic Barrier (MAB) and the Amazon-Orinoco Plume (AOP). Generalized linear mixed-effects models indicate that predictors for successful barrier crossing are the ability to raft with flotsam for the deep-water MAB, non-reef habitat usage for the freshwater and sediment-rich AOP, and large adult-size and large latitudinal-range for both barriers. Variation in larval-development mode, often thought to be broadly related to larval-dispersal potential, is not a significant predictor in either case. Many more species of greater taxonomic diversity cross the AOP than the MAB. Rafters readily cross both barriers but represent a much smaller proportion of AOP crossers than MAB crossers. Successful establishment after crossing both barriers may be facilitated by broad environmental tolerance associated with large body size and wide latitudinal-range. These results highlight the need to look beyond larval-dispersal potential and assess adult-biology traits when assessing determinants of successful movements across marine barriers. PMID:21920979

  14. Upstream dispersal of an invasive crayfish aided by a fish passage facility

    USGS Publications Warehouse

    Welsh, Stuart; Loughman, Zachary J.

    2015-01-01

    Fish passage facilities for reservoir dams have been used to restore habitat connectivity within riverine networks by allowing upstream passage for native species. These facilities may also support the spread of invasive species, an unintended consequence and potential downside of upstream passage structures. We documented dam passage of the invasive virile crayfish, Orconectes virilis (Hagen, 1870), at fish ladders designed for upstream passage of American eels, Anguilla rostrata (Lesueur, 1817), in the Shenandoah River drainage, USA. Ladder use and upstream passage of 11 virile crayfish occurred from 2007–2014 during periods of low river discharge (<30 m3s–1) and within a wide range of water temperatures from 9.0–28.6 °C. Virile crayfish that used the eel ladders were large adults with a mean carapace length and width of 48.0 mm and 24.1 mm, respectively. Our data demonstrated the use of species-specific fish ladders by a non-target non-native species, which has conservation and management implications for the spread of aquatic invasive species and upstream passage facilities. Specifically, managers should consider implementing long-term monitoring of fish passage facilities with emphasis on detection of invasive species, as well as methods to reduce or eliminate passage of invasive species. 

  15. An In Situ, Individual-Based Approach to Quantify Connectivity of Marine Fish: Ontogenetic Movements and Residency of Lingcod

    PubMed Central

    Bishop, Mary Anne; Reynolds, Brad F.; Powers, Sean P.

    2010-01-01

    As modern fishery assessments change in an effort to be more accurate and encompass the range of potential ecosystem interactions, critical information on the ecology of species including life history, intra and inter-specific competitive interactions and habitat requirements must be added to the standard fishery-dependent and independent data sets. One species whose movements and habitat associations greatly affects exploitation patterns is lingcod, Ophiodon elongatus, which support an economically important fishery along the coastal waters of the Pacific Coast of North America. High site fidelity and limited movements within nearshore areas are hypothesized to have resulted in high catchability, a major factor that has contributed to overfished stocks. Thus, assessing the level of movement and connectivity among lingcod subpopulations inhabiting nearshore habitats is a prerequisite to determining the condition of lingcod stocks. We used the Pacific Ocean Shelf Tracking (POST) Project acoustic receiver array in Alaska's Prince William Sound to monitor movements and residency of 21 acoustic-tagged lingcod for up to 16 months. Eight of sixteen lingcod (50%) initially aged at 2.5- to 3.5- years-old dispersed from their tag site. Dispersal was highly seasonal, occurring in two, five-week periods from mid-December through January and from mid-April through May. Dispersal in winter may be related to sexually immature lingcod or newly-mature male lingcod being displaced by territorial males. Spring dispersal may be indicative of the onset of migratory behavior where lingcod move out into Prince William Sound and possibly the offshore waters of the Gulf of Alaska. Our results reveal a pattern of ontogenetic dispersal as lingcod approach 4-years-old and exceed 50 cm total length. The large proportion of tagged fish migrating out of Port Gravina, their tagging site, reflects a high level of connectivity among Prince William Sound subpopulations. Our results also support the

  16. An in situ, individual-based approach to quantify connectivity of marine fish: ontogenetic movements and residency of lingcod.

    PubMed

    Bishop, Mary Anne; Reynolds, Brad F; Powers, Sean P

    2010-01-01

    As modern fishery assessments change in an effort to be more accurate and encompass the range of potential ecosystem interactions, critical information on the ecology of species including life history, intra and inter-specific competitive interactions and habitat requirements must be added to the standard fishery-dependent and independent data sets. One species whose movements and habitat associations greatly affects exploitation patterns is lingcod, Ophiodon elongatus, which support an economically important fishery along the coastal waters of the Pacific Coast of North America. High site fidelity and limited movements within nearshore areas are hypothesized to have resulted in high catchability, a major factor that has contributed to overfished stocks. Thus, assessing the level of movement and connectivity among lingcod subpopulations inhabiting nearshore habitats is a prerequisite to determining the condition of lingcod stocks. We used the Pacific Ocean Shelf Tracking (POST) Project acoustic receiver array in Alaska's Prince William Sound to monitor movements and residency of 21 acoustic-tagged lingcod for up to 16 months. Eight of sixteen lingcod (50%) initially aged at 2.5- to 3.5- years-old dispersed from their tag site. Dispersal was highly seasonal, occurring in two, five-week periods from mid-December through January and from mid-April through May. Dispersal in winter may be related to sexually immature lingcod or newly-mature male lingcod being displaced by territorial males. Spring dispersal may be indicative of the onset of migratory behavior where lingcod move out into Prince William Sound and possibly the offshore waters of the Gulf of Alaska. Our results reveal a pattern of ontogenetic dispersal as lingcod approach 4-years-old and exceed 50 cm total length. The large proportion of tagged fish migrating out of Port Gravina, their tagging site, reflects a high level of connectivity among Prince William Sound subpopulations. Our results also support the

  17. Patterns of connectivity among populations of a coral reef fish

    NASA Astrophysics Data System (ADS)

    Chittaro, P. M.; Hogan, J. D.

    2013-06-01

    Knowledge of the patterns and scale of connectivity among populations is essential for the effective management of species, but our understanding is still poor for marine species. We used otolith microchemistry of newly settled bicolor damselfish ( Stegastes partitus) in the Mesoamerican Reef System (MRS), Western Caribbean, to investigate patterns of connectivity among populations over 2 years. First, we assessed spatial and temporal variability in trace elemental concentrations from the otolith edge to make a `chemical map' of potential source reef(s) in the region. Significant otolith chemical differences were detected at three spatial scales (within-atoll, between-atolls, and region-wide), such that individuals were classified to locations with moderate (52 % jackknife classification) to high (99 %) accuracy. Most sites at Turneffe Atoll, Belize showed significant temporal variability in otolith concentrations on the scale of 1-2 months. Using a maximum likelihood approach, we estimated the natal source of larvae recruiting to reefs across the MRS by comparing `natal' chemical signatures from the otolith of recruits to the `chemical map' of potential source reef(s). Our results indicated that populations at both Turneffe Atoll and Banco Chinchorro supply a substantial amount of individuals to their own reefs (i.e., self-recruitment) and thus emphasize that marine conservation and management in the MRS region would benefit from localized management efforts as well as international cooperation.

  18. Hydration State and Aqueous Phase Connectivity Shape Microbial Dispersal Rates in Unsaturated Angular Pore Networks

    NASA Astrophysics Data System (ADS)

    Or, D.; Ebrahimi, A.

    2014-12-01

    The limited dispersal of self-propelled microorganisms and constrained nutrient transport in unsaturated soils are considered key factors in the promotion and maintenance of soil microbial diversity. Despite the importance of microbial dispersal to biogeochemical and ecological functioning of soil, little is known about how pore spaces and hydration conditions affect dispersal ranges and rates of motile bacteria. To address these questions quantitatively, we developed a novel 3-D pore network model (PNM) composed of triangular bonds connected to cubic (volumeless) bonds to mimic the salient geometrical and physical properties of natural pore spaces. Within this abstracted physical domain we employed individual based models for motile microorganisms that are capable of motion, nutrient consumption, growth and cell division. We focused on dispersal rates through the network as a function of hydration conditions through its impact on aqueous phase fragmentation that suppress nutrient diffusion (hence growth rates) and dispersal rates in good agreement with limited experimental data. Chemotactically-biased mean travel rates of microbial cells across the saturated PNM was ~3 mm/hr and decreased exponentially to 0.45 mm/hr for matric potential of (at dispersal practically ceases and cells are pinned by capillary forces). Individual-based results were upscaled to describe population scale dispersal rates, and PNM predictions considering different microbial cell sizes were in good agreement with experimental results for unsaturated soils. The role of convection for most unsaturated conditions was negligible relative to self-motility highlighting the need to constrain continuum models with respect to cell size and motility to imporve predictions of transport of motile microorganisms. The modeling platform confirms universal predictions based on percolation theory for the onset of aqueous phase fragmentation that limit dispersal and provide niches essential for species

  19. Does mating behaviour affect connectivity in marine fishes? Comparative population genetics of two protogynous groupers (Family Serranidae).

    PubMed

    Portnoy, D S; Hollenbeck, C M; Renshaw, M A; Cummings, N J; Gold, J R

    2013-01-01

    Pelagic larval duration (PLD) has been hypothesized to be the primary predictor of connectivity in marine fishes; however, few studies have examined the effects that adult reproductive behaviour may have on realized dispersal. We assessed gene flow (connectivity) by documenting variation in microsatellites and mitochondrial DNA sequences in two protogynous species of groupers, the aggregate spawning red hind, Epinephelus guttatus, and the single-male, harem-spawning coney, Cephalopholis fulva, to ask whether reproductive strategy affects connectivity. Samples of both species were obtained from waters off three islands (Puerto Rico, St. Thomas and St. Croix) in the Caribbean Sea. Despite the notion that aggregate spawning of red hind may facilitate larval retention, stronger signals of population structure were detected in the harem-spawning coney. Heterogeneity and/or inferred barriers, based on microsatellites, involved St. Croix (red hind and coney) and the west coast of Puerto Rico (coney). Heterogeneity and/or inferred barriers, based on mitochondrial DNA, involved St. Croix (coney only). Genetic divergence in both species was stronger for microsatellites than for mitochondrial DNA, suggesting sex-biased dispersal in both species. Long-term migration rates, based on microsatellites, indicated asymmetric gene flow for both species in the same direction as mean surface currents in the region. Red hind had higher levels of variation in microsatellites and lower levels of variation in mitochondrial DNA. Long-term effective size and effective number of breeders were greater for red hind; estimates of θ(f) , a proxy for long-term effective female size, were the same in both species. Patterns of gene flow in both species appear to stem in part from shared aspects of larval and adult biology, local bathymetry and surface current patterns. Differences in connectivity and levels of genetic variation between the species, however, likely stem from differences in behaviour

  20. Directed dispersal by rotational shepherding supports landscape genetic connectivity in a calcareous grassland plant.

    PubMed

    Rico, Yessica; Holderegger, Rolf; Boehmer, Hans Juergen; Wagner, Helene H

    2014-02-01

    Directed dispersal by animal vectors has been found to have large effects on the structure and dynamics of plant populations adapted to frugivory. Yet, empirical data are lacking on the potential of directed dispersal by rotational grazing of domestic animals to mediate gene flow across the landscape. Here, we investigated the potential effect of large-flock shepherding on landscape-scale genetic structure in the calcareous grassland plant Dianthus carthusianorum, whose seeds lack morphological adaptations to dispersal to animals or wind. We found a significant pattern of genetic structure differentiating population within grazed patches of three nonoverlapping shepherding systems and populations of ungrazed patches. Among ungrazed patches, we found a strong and significant effect of isolation by distance (r = 0.56). In contrast, genetic distance between grazed patches within the same herding system was unrelated to geographical distance but significantly related to distance along shepherding routes (r = 0.44). This latter effect of connectivity along shepherding routes suggests that gene flow is spatially restricted occurring mostly between adjacent populations. While this study used nuclear markers that integrate gene flow by pollen and seed, the significant difference in the genetic structure between ungrazed patches and patches connected by large-flock shepherding indicates the potential of directed seed dispersal by sheep across the landscape. PMID:24451046

  1. Assessing Dispersal Patterns of Fish Propagules from an Effective Mediterranean Marine Protected Area

    PubMed Central

    Di Franco, Antonio; Coppini, Giovanni; Pujolar, José Martin; De Leo, Giulio A.; Gatto, Marino; Lyubartsev, Vladyslav; Melià, Paco; Zane, Lorenzo; Guidetti, Paolo

    2012-01-01

    Successfully enforced marine protected areas (MPAs) have been widely demonstrated to allow, within their boundaries, the recovery of exploited species and beyond their boundaries, the spillover of juvenile and adult fish. Little evidence is available about the so-called ‘recruitment subsidy’, the augmented production of propagules (i.e. eggs and larvae) due to the increased abundance of large-sized spawners hosted within effective MPAs. Once emitted, propagules can be locally retained and/or exported elsewhere. Patterns of propagule retention and/or export from MPAs have been little investigated, especially in the Mediterranean. This study investigated the potential for propagule production and retention/export from a Mediterranean MPA (Torre Guaceto, SW Adriatic Sea) using the white sea bream, Diplodus sargus sargus, as a model species. A multidisciplinary approach was used combining 1) spatial distribution patterns of individuals (post-settlers and adults) assessed through visual census within Torre Guaceto MPA and in northern and southern unprotected areas, 2) Lagrangian simulations of dispersal based on an oceanographic model of the region and data on early life-history traits of the species (spawning date, pelagic larval duration) and 3) a preliminary genetic study using microsatellite loci. Results show that the MPA hosts higher densities of larger-sized spawners than outside areas, potentially guaranteeing higher propagule production. Model simulations and field observation suggest that larval retention within and long-distance dispersal across MPA boundaries allow the replenishment of the MPA and of exploited populations up to 100 km down-current (southward) from the MPA. This pattern partially agrees with the high genetic homogeneity found in the entire study area (no differences in genetic composition and diversity indices), suggesting a high gene flow. By contributing to a better understanding of propagule dispersal patterns, these findings provide

  2. Climate change poised to threaten hydrologic connectivity and endemic fishes in dryland streams

    PubMed Central

    Jaeger, Kristin L.; Olden, Julian D.; Pelland, Noel A.

    2014-01-01

    Protecting hydrologic connectivity of freshwater ecosystems is fundamental to ensuring species persistence, ecosystem integrity, and human well-being. More frequent and severe droughts associated with climate change are poised to significantly alter flow intermittence patterns and hydrologic connectivity in dryland streams of the American Southwest, with deleterious effects on highly endangered fishes. By integrating local-scale hydrologic modeling with emerging approaches in landscape ecology, we quantify fine-resolution, watershed-scale changes in habitat size, spacing, and connectance under forecasted climate change in the Verde River Basin, United States. Model simulations project annual zero-flow day frequency to increase by 27% by midcentury, with differential seasonal consequences on continuity (temporal continuity at discrete locations) and connectivity (spatial continuity within the network). A 17% increase in the frequency of stream drying events is expected throughout the network with associated increases in the duration of these events. Flowing portions of the river network will diminish between 8% and 20% in spring and early summer and become increasingly isolated by more frequent and longer stretches of dry channel fragments, thus limiting the opportunity for native fishes to access spawning habitats and seasonally available refuges. Model predictions suggest that midcentury and late century climate will reduce network-wide hydrologic connectivity for native fishes by 6–9% over the course of a year and up to 12–18% during spring spawning months. Our work quantifies climate-induced shifts in stream drying and connectivity across a large river network and demonstrates their implications for the persistence of a globally endemic fish fauna. PMID:25136090

  3. Using elemental chemistry of fish otoliths to determine connectivity between estuarine and coastal habitats

    NASA Astrophysics Data System (ADS)

    Gillanders, B. M.

    2005-07-01

    Connectivity between estuarine and coastal populations is poorly understood but fundamental to the study of population dynamics, as well as the design of effective conservation and management strategies. Naturally occurring elemental signatures (or composition) in the otoliths of fish are an ideal natural tag due to the metabolic inertness of otoliths, continuous growth including daily increments and incorporation of elements that are influenced by environmental variables. In this paper, I review the use of otolith chemistry to determine connectivity between estuarine and coastal habitats focusing on assumptions of using elemental signatures as natural tags, consequences of violating these assumptions and finally providing examples of the application of natural tags to determine connectivity. As a first step to determining connectivity, it is important to determine whether fish residing in different estuaries do in fact have different elemental signatures. Spatial differences must be determined for each species of interest since variability has been found between species collected from the same location. For retrospective determination of origins of fish, it is also necessary to ensure either that there is no temporal variation at both the small (e.g. among months within a year) and large scale (e.g. among years) or to match adults to the appropriate year class of juveniles. In addition, fish should be collected from all possible source groups contributing to the group mixture. The majority of studies that show connectivity between estuarine and open coastal populations using otolith chemistry have determined the contribution of different habitats or estuaries to the adult population, although natal homing has also been examined.

  4. Supporting decision-making for improving longitudinal connectivity for diadromous and potamodromous fishes in complex catchments.

    PubMed

    Brevé, Niels W P; Buijse, Anthonie D; Kroes, Martin J; Wanningen, Herman; Vriese, Frederik T

    2014-10-15

    Preservation and restoration of Europe's endangered migratory fish species and habitats are high on the international river basin policy agenda. Improvement through restoration of longitudinal connectivity is seen as an important measure, but although prioritization of in-stream barriers has been addressed at local and regional levels the process still lacks adequate priority on the international level. This paper introduces a well-tested method, designed to help decision makers achieve the rehabilitation of targeted ichthyofauna more successfully. This method assesses artificial barriers within waters designated under the Water Framework Directive (WFD), Europe's main legislative driver for ecological improvement of river basins. The method aggregates migratory fish communities (both diadromous and potamodromous) into functional biological units (ecological fish guilds) and defines their most pressing habitat requirements. Using GIS mapping and spatial analysis of the potential ranges (fish zonation) we pin-point the most important barriers, per guild. This method was developed and deployed over a 12 year period as a practical case study, fitting data derived from the 36 regional water management organisations in the Netherlands. We delivered national advice on the prioritization of a total of 2924 barriers located within WFD water bodies, facilitating migration for all 18 indigenous migratory fish species. Scaling up to larger geographical areas can be achieved using datasets from other countries to link water body typologies to distribution ranges of migratory fish species. PMID:25084228

  5. Long Distance Dispersal and Connectivity in Amphi-Atlantic Corals at Regional and Basin Scales

    PubMed Central

    Nunes, Flavia L. D.; Norris, Richard D.; Knowlton, Nancy

    2011-01-01

    Among Atlantic scleractinian corals, species diversity is highest in the Caribbean, but low diversity and high endemism are observed in various peripheral populations in central and eastern Atlantic islands and along the coasts of Brazil and West Africa. The degree of connectivity between these distantly separated populations is of interest because it provides insight into processes at both evolutionary and ecological time scales, such as speciation, recruitment dynamics and the persistence of coral populations. To assess connectivity in broadly distributed coral species of the Atlantic, DNA sequence data from two nuclear markers were obtained for six coral species spanning their distributional ranges. At basin-wide scales, significant differentiation was generally observed among populations in the Caribbean, Brazil and West Africa. Concordance of patterns in connectivity among co-distributed taxa indicates that extrinsic barriers, such as the Amazon freshwater plume or long stretches of open ocean, restrict dispersal of coral larvae from region to region. Within regions, dispersal ability appears to be influenced by aspects of reproduction and life history. Two broadcasting species, Siderastrea siderea and Montastraea cavernosa, were able to maintain gene flow among populations separated by as much as 1,200 km along the coast of Brazil. In contrast, brooding species, such as Favia gravida and Siderastrea radians, had more restricted gene flow along the Brazilian coast. PMID:21799816

  6. Vicariance and dispersal across Baja California in disjunct marine fish populations.

    PubMed

    Bernardi, Giacomo; Findley, Lloyd; Rocha-Olivares, Axayacatl

    2003-07-01

    Population disjunctions, as a first step toward complete allopatry, present an interesting situation to study incipient speciation. The geological formation of the Baja California Peninsula currently divides 19 species of fish into disjunct populations that are found on its Pacific Coast and in the northern part of the Gulf of California (also called the Sea of Cortez), but are absent from the Cape (Cabo San Lucas) region. We studied the genetic makeup of disjunct populations for 12 of these 19 fish species. Phylogeographic patterns for the 12 species can be separated into two major classes: a first group (eight species) showed reciprocal monophyly and high genetic divergence between disjunct populations. A second group (four species) displayed what appeared to be panmictic populations. Population structure between Pacific Coast populations, across the Punta Eugenia biogeographic boundary, was also evaluated. While dispersal potential (inferred by pelagic larval duration) was a poor predictor of population structure between Gulf of California and Pacific populations, we found that population genetic subdivision along the Pacific Coast at Punta Eugenia was always positively correlated with differentiation between Pacific and Gulf of California populations. Vicariant events, ongoing gene flow, and ecological characteristics played essential roles in shaping the population structures observed in this study. PMID:12940364

  7. Polyelectrolyte Microcapsules Dispersed in Silicone Rubber for in Vivo Sampling in Fish Brains.

    PubMed

    Xu, Jianqiao; Wu, Rongben; Huang, Shuyao; Yang, Muzi; Liu, Yan; Liu, Yuan; Jiang, Ruifen; Zhu, Fang; Ouyang, Gangfeng

    2015-10-20

    Direct detection of fluoxetine and its metabolite norfluoxetine in living fish brains was realized for the first time by using a novel solid-phase microextraction fiber, which was prepared by mixing the polyelectrolyte in the oligomer of silicone rubber and followed by in-mold heat-curing. The polyelectrolyte was finally encased in microcapsules dispersed in the cured silicone rubber. The fiber exhibited excellent interfiber reproducibility (5.4-7.1%, n = 6), intrafiber reproducibility (3.7-4.6%, n = 6), and matrix effect-resistant capacity. Due to the capacity of simultaneously extracting the neutral and the protonated species of the analytes at physiological pH, the fiber exhibited high extraction efficiencies to fluoxetine and norfluoxetine. Besides, the effect of the salinity on the extraction performance and the competitive sorption between the analytes were also evaluated. Based on the small-sized custom-made fiber, the concentrations of fluoxetine and norfluoxetine in the brains of living fish, which were exposed to waterborne fluoxetine at an environmentally relevant concentration, were determined and found 4.4 to 9.2 and 5.0 to 9.2 times those in the dorsal-epaxial muscle. The fiber can be used to detect various protonated bioactive compounds in living animal tissues. PMID:26403643

  8. Effects of dynamic landscape elements on fish dispersal: the example of creek chub (Semotilus atromaculatus).

    PubMed

    Boizard, J; Magnan, P; Angers, B

    2009-02-01

    Barriers along a watercourse and interconnections between drainage systems are dynamic landscape elements that are expected to play major roles in the dispersal and genetic structure of fish species. The objective of this study was to assess the role of these elements using creek chub (Semotilus atromaculatus) in the Mastigouche Wildlife Reserve (Québec, Canada) as model. Numerous impassable waterfalls and interconnections among drainage systems were inferred with geographic information systems and confirmed de visu. The analysis of 32 populations using seven nuclear microsatellites revealed the presence of three genetically distinct groups. Some groups were found upstream of impassable barriers and in adjacent portions of distinct drainage systems. Admixture among groups was also detected in some populations. Constraining phylogenetic procedures as well as Mantel correlation tests confirmed that the genetic structure is more likely to result from interconnections between the drainage systems than from the permanent network. This study indicates that landscape elements such as interconnections are of major importance for circumventing impassable barriers and colonizing lakes that are otherwise inaccessible. Such an approach could be relevant for determining the origins of fish species (i.e. native vs. introduced) in the context of conservation. PMID:19161466

  9. Assessing connectivity of estuarine fishes based on stable isotope ratio analysis

    NASA Astrophysics Data System (ADS)

    Herzka, Sharon Z.

    2005-07-01

    Assessing connectivity is fundamental to understanding the population dynamics of fishes. I propose that isotopic analyses can greatly contribute to studies of connectivity in estuarine fishes due to the high diversity of isotopic signatures found among estuarine habitats and the fact that variations in isotopic composition at the base of a food web are reflected in the tissues of consumers. Isotopic analysis can be used for identifying nursery habitats and estimating their contribution to adult populations. If movement to a new habitat is accompanied by a shift to foods of distinct isotopic composition, recent immigrants and residents can be distinguished based on their isotopic ratios. Movement patterns thus can be reconstructed based on information obtained from individuals. A key consideration is the rate of isotopic turnover, which determines the length of time that an immigrant to a given habitat will be distinguishable from a longtime resident. A literature survey indicated that few studies have measured turnover rates in fishes and that these have focused on larvae and juveniles. These studies reveal that biomass gain is the primary process driving turnover rates, while metabolic turnover is either minimal or undetectable. Using a simple dilution model and biomass-specific growth rates, I estimated that young fishes with fast growth rates will reflect the isotopic composition of a new diet within days or weeks. Older or slower-growing individuals may take years or never fully equilibrate. Future studies should evaluate the factors that influence turnover rates in fishes during various stages of the life cycle and in different tissues, as well as explore the potential for combining stable isotope and otolith microstructure analyses to examine the relationship between demographic parameters, movement and connectivity.

  10. Interbasin water transfer, riverine connectivity, and spatial controls on fish biodiversity

    USGS Publications Warehouse

    Grant, Evan H. Campbell; Lynch, Heather J.; Muneepeerakul, Rachata; Muthukumarasamy, Arunachalam; Rodríguez-Iturbe, Ignacio; Fagan, William F.

    2012-01-01

    Background Large-scale inter-basin water transfer (IBWT) projects are commonly proposed as solutions to water distribution and supply problems. These problems are likely to intensify under future population growth and climate change scenarios. Scarce data on the distribution of freshwater fishes frequently limits the ability to assess the potential implications of an IBWT project on freshwater fish communities. Because connectivity in habitat networks is expected to be critical to species' biogeography, consideration of changes in the relative isolation of riverine networks may provide a strategy for controlling impacts of IBWTs on freshwater fish communities Methods/Principal Findings Using empirical data on the current patterns of freshwater fish biodiversity for rivers of peninsular India, we show here how the spatial changes alone under an archetypal IBWT project will (1) reduce freshwater fish biodiversity system-wide, (2) alter patterns of local species richness, (3) expand distributions of widespread species throughout peninsular rivers, and (4) decrease community richness by increasing inter-basin similarity (a mechanism for the observed decrease in biodiversity). Given the complexity of the IBWT, many paths to partial or full completion of the project are possible. We evaluate two strategies for step-wise implementation of the 11 canals, based on economic or ecological considerations. We find that for each step in the project, the impacts on freshwater fish communities are sensitive to which canal is added to the network. Conclusions/Significance Importantly, ecological impacts can be reduced by associating the sequence in which canals are added to characteristics of the links, except for the case when all 11 canals are implemented simultaneously (at which point the sequence of canal addition is inconsequential). By identifying the fundamental relationship between the geometry of riverine networks and freshwater fish biodiversity, our results will aid in

  11. Stretched to the limit; can a short pelagic larval duration connect adult populations of an Indo-Pacific diadromous fish (Kuhlia rupestris)?

    PubMed

    Feutry, P; Vergnes, A; Broderick, D; Lambourdière, J; Keith, P; Ovenden, J R

    2013-03-01

    Freshwater species on tropical islands face localized extinction and the loss of genetic diversity. Their habitats can be ephemeral due to variability in freshwater run-off and erosion. Even worse, anthropogenic effects on these ecosystems are intense. Most of these species are amphidromous or catadromous (i.e. their life cycle includes a marine larval phase), which buffers them against many of these effects. A long pelagic larval duration (PLD) was thought to be critical to ensure the colonization and persistence in tropical islands, but recent findings indicated that several species with short PLDs are successful in those ecosystems. To test the potential of a short PLD in maintaining genetic connectivity and forestalling extirpation, we studied Kuhlia rupestris, a catadromous fish species with an extensive distribution in the western Pacific and Indian Oceans. Using a combination of molecular genetic markers (13 microsatellite loci and two gene regions from mtDNA) and modelling of larval dispersal, we show that a short PLD constrains genetic connectivity over a wide geographical range. Molecular markers showed that the short PLD did not prevent genetic divergence through evolutionary time and speciation has occurred or is occurring. Modelling of larvae dispersal suggested limited recent connectivity between genetically homogeneous populations across the Coral Sea. However, a short PLD can maintain connectivity on a subocean basin scale. Conservation and management of tropical diadromous species needs to take into account that population connectivity may be more limited than previously suspected in those species. PMID:23294379

  12. Host Fish of Four Species of Unionid Mussels and the Dispersal of their Larvae with the Fish Movement

    NASA Astrophysics Data System (ADS)

    Kondo, Mio; Ito, Kengo; Senge, Masateru

    Host fish of each mussel was examined in a biotope pond, a drainage canal and fishway between them in Gifu Prefecture from May to October 2008. The main host fish was Zacco platypus in Unio douglasiae and Lanceolaria grayana, Nipponocypris sieboldii in Anodonta sp. and Pronodularia japonensis. In the fish caught at fishway, intensity and total number of glochidium were more the descending fish from the biotope pond than the ascending one from the drainage canal, which suggests that the biotope pond is now the base of supply of juveniles to the neighboring areas.

  13. Experimental evaluation of connectivity influence on dispersivity under confined and unconfined radial convergent flow conditions

    NASA Astrophysics Data System (ADS)

    Guzzi, Silvia; Molinari, Antonio; Fallico, Carmine; Pedretti, Daniele

    2014-05-01

    Heterogeneity and connectivity have a significant impact on the fate and transport of contaminants due to the occurrence of formations with largest permeability than the surrounding geological materials, which can originate preferential pathways in groundwater system. These issues are usually addressed by tracer tests and a radial convergent (RC) flow setting is typically selected for convenience but more complicated for model interpretation than uniform flow transport. An experimental investigation was performed using RC tracer tests in a 3D intermediate scale physical model to illustrate the role of connected features on the estimation of dispersivity using the classical Sauty solution and the method of moments, under confined and unconfined aquifer conditions. The physical model consists of 26 piezometers located at difference distances from a constant-discharge central pumping well. The box is filled with gravel channels embedded in a sandy matrix and organized in different layers. Materials have been well characterized before and after the test. For the confined configuration, a silt layer was placed above the previous layers. Tracer tests were performed using potassium iodide solutions with concentration of 3•10-3 M and under a constant pumping flow rate of 0.05 L/s. To mimic a pulse injection in each piezometer we used syringes and pipes, whereas a probe allowed continuous measuring of tracer concentration. Average velocity and longitudinal dispersion coefficient were defined from the first and second central moment of the observed breakthrough curves for each piezometer (integrated over the outflow boundary of the domain) and using the classical curve matching from the Sauty's solution at different Péclet numbers. Results reveal in some cases that estimates of hydrodynamic parameters from the Sauty solution and the method of moments seem to be different. This is related to the different basic assumptions of the two methods applied, and especially because

  14. Effects on electrical distribution networks of dispersed power generation at high levels of connection penetration

    SciTech Connect

    Longrigg, P

    1983-07-01

    The advent and deployment of significant levels of photovoltaic and wind energy generation in the spatially dispersed mode (i.e., residential and intermediate load centers) may have deleterious effects upon existing protective relay equipment and its time-current coordination on radial distribution circuits to which power conditioning equipment may be connected for power sell-back purposes. The problems that may arise involve harmonic injection from power conditioning inverters that can affect protective relays and cause excessive voltage and current from induced series and parallel resonances on feeders and connected passive equipment. Voltage regulation, var requirements, and consumer metering can also be affected by this type of dispersed generation. The creation of islands of supply is also possible, particularly on rural supply systems. This paper deals mainly with the effects of harmonics and short-circuit currents from wind energy conversion systems (WECS) and photovoltaic (PV) systems upon the operating characteristics of distribution networks and relays and other protective equipment designed to ensure the safety and supply integrity of electrical utility networks. Traditionally, electrical supply networks have been designed for one-way power flow-from generation to load, with a balance maintained between the two by means of automatic generation and load-frequency controls. Dispersed generation, from renewables like WECS or PV or from nonrenewable resources, can change traditional power flow. These changes must be dealt with effectively if renewable energy resources are to be integrated into the utility distribution system. This paper gives insight into these problems and proposes some solutions.

  15. Trophic connections in Lake Superior Part II: the nearshore fish community

    USGS Publications Warehouse

    Gamble, A.E.; Hrabik, T.R.; Yule, D.L.; Stockwell, J.D.

    2011-01-01

    We use detailed diet analyses of the predominant planktivorous, benthivorous and piscivorous fish species from Lake Superior to create a nearshore (bathymetric depths Mysis diluviana and Diporeia spp). Although the piscivorous fishes like lean lake trout (Salvelinus namaycush) fed to a lesser extent on Diporeia and Mysis, they were still strongly connected to these macroinvertebrates, which were consumed by their primary prey species (sculpin spp., rainbow smelt Osmerus mordax, and coregonines). The addition of Bythotrephes to summer/fall cisco and lake whitefish diets, and the decrease in rainbow smelt in lean lake trout diets (replaced by coregonines) were the largest observed differences relative to historic Lake Superior diet studies. Although the offshore food web of Lake Superior was simpler than nearshore in terms of number of fish species present, the two areas had remarkably similar food web structures, and both fish communities were primarily supported by Mysis and Diporeia. We conclude that declines in Mysis or Diporeia populations would have a significant impact on energy flow in Lake Superior. The food web information we generated can be used to better identify management strategies for Lake Superior.

  16. Connectivity, passability and heterogeneity interact to determine fish population persistence in river networks

    PubMed Central

    Samia, Yasmine; Lutscher, Frithjof; Hastings, Alan

    2015-01-01

    The movement of fish in watersheds is frequently inhibited by human-made migration barriers such as dams or culverts. The resulting lack of connectivity of spatial subpopulations is often cited as a cause for observed population decline. We formulate a matrix model for a spatially distributed fish population in a watershed, and we investigate how location and other characteristics of a single movement barrier impact the asymptotic growth rate of the population. We find that while population growth rate often decreases with the introduction of a movement obstacle, it may also increase due to a ‘retention effect’. Furthermore, obstacle mortality greatly affects population growth rate. In practice, different connectivity indices are used to predict population effects of migration barriers, but the relation of these indices to population growth rates in demographic models is often unclear. When comparing our results with the dentritic connectivity index, we see that the index captures neither the retention effect nor the influences of obstacle mortality. We argue that structural indices cannot entirely replace more detailed demographic models to understand questions of persistence and extinction. We advocate the development of novel functional indices and characteristics. PMID:26311313

  17. Connectivity, passability and heterogeneity interact to determine fish population persistence in river networks.

    PubMed

    Samia, Yasmine; Lutscher, Frithjof; Hastings, Alan

    2015-09-01

    The movement of fish in watersheds is frequently inhibited by human-made migration barriers such as dams or culverts. The resulting lack of connectivity of spatial subpopulations is often cited as a cause for observed population decline. We formulate a matrix model for a spatially distributed fish population in a watershed, and we investigate how location and other characteristics of a single movement barrier impact the asymptotic growth rate of the population. We find that while population growth rate often decreases with the introduction of a movement obstacle, it may also increase due to a 'retention effect'. Furthermore, obstacle mortality greatly affects population growth rate. In practice, different connectivity indices are used to predict population effects of migration barriers, but the relation of these indices to population growth rates in demographic models is often unclear. When comparing our results with the dentritic connectivity index, we see that the index captures neither the retention effect nor the influences of obstacle mortality. We argue that structural indices cannot entirely replace more detailed demographic models to understand questions of persistence and extinction. We advocate the development of novel functional indices and characteristics. PMID:26311313

  18. Designing long-term fish community assessments in connecting channels: Lessons from the Saint Marys River

    USGS Publications Warehouse

    Schaeffer, Jeff; Rogers, Mark W.; Fielder, David G.; Godby, Neal; Bowen, Anjanette K.; O'Connor, Lisa; Parrish, Josh; Greenwood, Susan; Chong, Stephen; Wright, Greg

    2014-01-01

    Long-term surveys are useful in understanding trends in connecting channel fish communities; a gill net assessment in the Saint Marys River performed periodically since 1975 is the most comprehensive connecting channels sampling program within the Laurentian Great Lakes. We assessed efficiency of that survey, with intent to inform development of assessments at other connecting channels. We evaluated trends in community composition, effort versus estimates of species richness, ability to detect abundance changes for four species, and effects of subsampling yellow perch catches on size and age-structure metrics. Efficiency analysis revealed low power to detect changes in species abundance, whereas reduced effort could be considered to index species richness. Subsampling simulations indicated that subsampling would have allowed reliable estimates of yellow perch (Perca flavescens) population structure, while greatly reducing the number of fish that were assigned ages. Analyses of statistical power and efficiency of current sampling protocols are useful for managers collecting and using these types of data as well as for the development of new monitoring programs. Our approach provides insight into whether survey goals and objectives were being attained and can help evaluate ability of surveys to answer novel questions that arise as management strategies are refined.

  19. Dispersal

    USGS Publications Warehouse

    2001-01-01

    The ability of species to migrate and disperse is a trait that has interested ecologists for many years. Now that so many species and ecosystems face major environmental threats from habitat fragmentation and global climate change, the ability of species to adapt to these changes by dispersing, migrating, or moving between patches of habitat can be crucial to ensuring their survival. This book provides a timely and wide-ranging overview of the study of dispersal and incorporates much of the latest research. The causes, mechanisms, and consequences of dispersal at the individual, population, species and community levels are considered. The potential of new techniques and models for studying dispersal, drawn from molecular biology and demography, is also explored. Perspectives and insights are offered from the fields of evolution, conservation biology and genetics. Throughout the book, theoretical approaches are combined with empirical data, and care has been taken to include examples from as wide a range of species as possible.

  20. Dispersants have limited effects on exposure rates of oil spills on fish eggs and larvae in shelf seas.

    PubMed

    Vikebø, Frode B; Rønningen, Petter; Meier, Sonnich; Grøsvik, Bjørn Einar; Lien, Vidar S

    2015-05-19

    Early life stages of fish are particularly vulnerable to oil spills. Simulations of overlap of fish eggs and larvae with oil from different oil-spill scenarios, both without and with the dispersant Corexit 9500, enable quantitative comparisons of dispersants as a mitigation alternative. We have used model simulations of a blow out of 4500 m(3) of crude oil per day (Statfjord light crude) for 30 days at three locations along the Norwegian coast. Eggs were released from nine different known spawning grounds, in the period from March 1st until the end of April, and all spawning products were followed for 90 days from the spill start at April first independent of time for spawning. We have modeled overlap between spawning products and oil concentrations giving a total polycyclic hydrocarbon (TPAH) concentration of more than 1.0 or 0.1 ppb (μg/l). At these orders of magnitude, we expect acute mortality or sublethal effects, respectively. In general, adding dispersants results in higher concentrations of TPAHs in a reduced volume of water compared to not adding dispersants. Also, the TPAHs are displaced deeper in the water column. Model simulations of the spill scenarios showed that addition of chemical dispersant in general moderately decreased the fraction of eggs and larvae that were exposed above the selected threshold values. PMID:25875213

  1. Floating along buoyancy levels: Dispersal and survival of western Baltic fish eggs

    NASA Astrophysics Data System (ADS)

    Petereit, C.; Hinrichsen, H.-H.; Franke, A.; Köster, F. W.

    2014-03-01

    Vertical distribution is an important feature of pelagic fish eggs and yolk sac larvae impacting their survival and dispersal, especially in heterogeneous and highly variable estuarine environments like the Baltic Sea. Egg densities determining the vertical distribution pattern were experimentally ascertained for cod (Gadus morhua), plaice (Pleuronectes platessa) and flounder (Platichthys flesus) from the western Baltic Sea. Plaice eggs floated at lower mean (±standard deviation) density range (1.0136 ± 0.0007 g cm-3) compared to cod (1.0146 ± 0.0009 g cm-3) and flounder eggs (1.0160 ± 0.0015 g cm-3), which floated on the highest density level. In flounder egg diameter was significantly related to egg density and in cod a weak correlation could be found between egg dry weight and density. All other relationships between female size, egg size, egg dry weight and egg density were not significant for any of the species. Available egg density data for Baltic Sea cod, plaice and flounder are summarized considering ICES subdivisions and stock management units. A hydrodynamic drift modeling approach was applied releasing drifters in the Belt Sea continuously from December to May, covering the species’ spawning seasons. The model implemented experimentally derived egg density ranges and included ontogenetic egg density modifications for cod eggs, increasing egg density from a late egg development stage to first hatch. A drifter was removed from the model, i.e. considered dead, when its initially prescribed density value exceeded the density range available at the temporally resolved geographical positions along the drift trajectories. Highest survival occurred during releases in April and May but no cohorts survived if they were drifted east into the central Arkona Basin or the central Baltic Sea, irrespective of whether a major Baltic Inflow (1992/1993) or a stagnation-year (1987/1988) was simulated. The dispersal characteristics of the surviving yolk sac larvae of

  2. Temporal variability in estuarine fish otolith elemental fingerprints: Implications for connectivity assessments

    NASA Astrophysics Data System (ADS)

    Reis-Santos, Patrick; Gillanders, Bronwyn M.; Tanner, Susanne E.; Vasconcelos, Rita P.; Elsdon, Travis S.; Cabral, Henrique N.

    2012-10-01

    The chemical composition of fish otoliths can provide valuable information for determining the nursery value of estuaries to adult populations of coastal fishes. However, understanding temporal variation in elemental fingerprints at different scales is important as it can potentially confound spatial discrimination among estuaries. Otolith elemental ratios (Li:Ca, Mg:Ca, Mn:Ca, Cu:Ca, Sr:Ca, Ba:Ca and Pb:Ca) of Platichthys flesus and Dicentrarchus labrax, from several estuaries along the Portuguese coast in two years and three seasons (spring, summer and autumn) within a year, were determined via Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Elemental fingerprints varied significantly among years and seasons within a year but we achieved accurate classifications of juvenile fish to estuarine nursery of origin (77-96% overall cross-validated accuracy). Although elemental fingerprints were year-specific, variation among seasons did not hinder spatial discrimination. Estuarine fingerprints of pooled seasonal data were representative of the entire juvenile year class and attained high discrimination (77% and 80% overall cross-validated accuracy for flounder and sea bass, respectively). Incorporating seasonal variation resulted in up to an 11% increase in correct classification of individual estuaries, in comparison to seasons where accuracies were lowest. Overall, understanding the implications of temporal variations in otolith chemistry for spatial discrimination is key to establish baseline data for connectivity studies.

  3. Dispersant use as a response to oil spills: toxicological effects on fish cardiac performance.

    PubMed

    Milinkovitch, Thomas; Thomas-Guyon, Hélène; Lefrançois, Christel; Imbert, Nathalie

    2013-04-01

    Dispersant use is a controversial technique used to respond to oil spills in nearshore areas. In order to assess the toxicity of this technique, this study evaluated the cardiac toxicological effects on juvenile golden grey mullets Liza aurata exposed for 48 h to either dispersant alone, chemically dispersed oil, mechanically dispersed oil, the water-soluble fraction of oil or a control condition. Following exposure, the positive inotropic effects of adrenaline were assessed in order to evaluate a potential impairment on the cardiac performance. The results revealed an impairment of the positive inotropic effects of adrenaline for all the contaminants (single dispersant, dispersed and undispersed oil, water-soluble fraction of oil). This suggests that: (1) cardiac performance is a valuable parameter to study the physiopathological effects of dispersed oil; (2) dispersant application is likely to impair cardiac performance. PMID:22976195

  4. Inverse approach to estimating larval dispersal reveals limited population connectivity along 700 km of wave-swept open coast.

    PubMed

    Hameed, Sarah O; White, J Wilson; Miller, Seth H; Nickols, Kerry J; Morgan, Steven G

    2016-06-29

    Demographic connectivity is fundamental to the persistence and resilience of metapopulations, but our understanding of the link between reproduction and recruitment is notoriously poor in open-coast marine populations. We provide the first evidence of high local retention and limited connectivity among populations spanning 700 km along an open coast in an upwelling system. Using extensive field measurements of fecundity, population size and settlement in concert with a Bayesian inverse modelling approach, we estimated that, on average, Petrolisthes cinctipes larvae disperse only 6.9 km (±25.0 km s.d.) from natal populations, despite spending approximately six weeks in an open-coast system that was once assumed to be broadly dispersive. This estimate differed substantially from our prior dispersal estimate (153.9 km) based on currents and larval duration and behaviour, revealing the importance of employing demographic data in larval dispersal estimates. Based on this estimate, we predict that demographic connectivity occurs predominantly among neighbouring populations less than 30 km apart. Comprehensive studies of larval production, settlement and connectivity are needed to advance an understanding of the ecology and evolution of life in the sea as well as to conserve ecosystems. Our novel approach provides a tractable framework for addressing these questions for species occurring in discrete coastal populations. PMID:27358362

  5. Genes and song: genetic and social connections in fragmented habitat in a woodland bird with limited dispersal.

    PubMed

    Pavlova, Alexandra; Amos, J Nevil; Goretskaia, Maria I; Beme, Irina R; Buchanan, Katherine L; Takeuchi, Naoko; Radford, James Q; Sunnucks, Paul

    2012-07-01

    Understanding the processes leading to population declines in fragmented landscapes is essential for successful conservation management. However, isolating the influence of disparate processes, and dispersal in particular, is challenging. The Grey Shrike-thrush, Colluricincla harmonica, is a sedentary woodland-dependent songbird, with learned vocalizations whose incidence in suitable habitat patches falls disproportionally with decline in tree cover in the landscape. Although it has been suggested that gaps in tree cover might act as barriers to its dispersal, the species remains in many remnants of native vegetation in agricultural landscapes, suggesting that it may have responded to habitat removal and fragmentation by maintaining or even increasing dispersal distances. We quantified population connectivity of the Grey Shrike-thrush in a system fragmented over more than 120 years using genetic (microsatellites) and acoustic (song types) data. First, we tested for population genetic and acoustic structure at regional and local scales in search of barriers to dispersal or gene flow and signals of local spatial structuring indicative of restricted dispersal or localized acoustic similarity. Then we tested for effects of habitat loss and fragmentation on genetic and acoustic connectivity by fitting alternative models of mobility (isolation-by-distance [the null model] and reduced and increased movement models) across treeless vs. treed areas. Birds within -5 km of each other had more similar genotypes and song types than those farther away, suggesting that dispersal and song matching are limited in the region. Despite restricted dispersal detected for females (but not males), populations appeared to be connected by gene flow and displayed some cultural (acoustic) connectivity across the region. Fragmentation did not appear to impact greatly the dispersal of the Grey Shrike-thrush: none of the mobility models fit the genetic distances of males, whereas for females, an

  6. Simulating mechanisms for dispersal, production and stranding of small forage fish in temporary wetland habitats

    USGS Publications Warehouse

    Yurek, Simeon; DeAngelis, Donald L.; Trexler, Joel C.; Jopp, Fred; Donalson, Douglas D.

    2013-01-01

    Movement strategies of small forage fish (<8 cm total length) between temporary and permanent wetland habitats affect their overall population growth and biomass concentrations, i.e., availability to predators. These fish are often the key energy link between primary producers and top predators, such as wading birds, which require high concentrations of stranded fish in accessible depths. Expansion and contraction of seasonal wetlands induce a sequential alternation between rapid biomass growth and concentration, creating the conditions for local stranding of small fish as they move in response to varying water levels. To better understand how landscape topography, hydrology, and fish behavior interact to create high densities of stranded fish, we first simulated population dynamics of small fish, within a dynamic food web, with different traits for movement strategy and growth rate, across an artificial, spatially explicit, heterogeneous, two-dimensional marsh slough landscape, using hydrologic variability as the driver for movement. Model output showed that fish with the highest tendency to invade newly flooded marsh areas built up the largest populations over long time periods with stable hydrologic patterns. A higher probability to become stranded had negative effects on long-term population size, and offset the contribution of that species to stranded biomass. The model was next applied to the topography of a 10 km × 10 km area of Everglades landscape. The details of the topography were highly important in channeling fish movements and creating spatiotemporal patterns of fish movement and stranding. This output provides data that can be compared in the future with observed locations of fish biomass concentrations, or such surrogates as phosphorus ‘hotspots’ in the marsh.

  7. Floods, fish, and people: Connecting biogeochemical fluxes to aquatic ecosystem functions and people (Invited)

    NASA Astrophysics Data System (ADS)

    Holtgrieve, G. W.; Arias, M. E.; Chheng, P.

    2013-12-01

    The Lower Mekong River basin, including Tonle Sap Lake (TSL), is the largest inland fishery in the world and a dominant source of protein and income for much of Southeast Asia. Maintaining ecosystem productivity in the face of large-scale environmental change from hydroelectric dams and climate change is critical for economic and social well-being in the region. Yet, we currently lack the most basic understanding of how hydrologic variation relates to fisheries production, nutritional quality, and ultimately livelihoods of people. We will describe past, present, and future research to establish mechanistic connections between the hydrology, ecology, and sustainability of the Mekong ecosystem. Past research includes application of a state-space oxygen mass balance model and continuous dissolved oxygen measurements from four locations to provide the first estimates of gross primary productivity (GPP) and ecosystem respiration (ER) for the Tonle Sap. GPP averaged 4.1 × 2.3 g O2 m-3 d-1 with minimal differences among sites, while ER averaged 24.9 × 20.0 g O2 m-3 d-1, but had greater than six-fold variation among sites. Using our measurements of GPP, we calibrated a hydrodynamic-productivity model and predicted aquatic net primary production of 2.0 × 0.2 g C m-2 d-1 (2.4 × 0.2 million tonnes C y-1). Present research is using stable isotope and fatty acid methyl ester biomarkers to investigate basal carbon sources to the fishery, focusing specifically on the role of biogenic methane oxidation in supporting the food web. Individuals a wide variety of taxa had tissue carbon isotope values (δ13C) ranging from -36 to -57 per mil. These extremely depleted values are best explained by utilization of biogenic methane by methane oxidizing bacteria (MOB) and subsequent grazing of these bacterial by benthic insects and ultimately fishes. The presence of MOB in the food web was confirmed by identifying 16:1ω8 and 18:1ω8 FAME biomarkers specific to these bacteria in fish

  8. Electrical synapses connect a network of gonadotropin releasing hormone neurons in a cichlid fish

    PubMed Central

    Ma, Yunyong; Hu, Caroline K.; Huguenard, John R.; Fernald, Russell D.

    2015-01-01

    Initiating and regulating vertebrate reproduction requires pulsatile release of gonadotropin-releasing hormone (GnRH1) from the hypothalamus. Coordinated GnRH1 release, not simply elevated absolute levels, effects the release of pituitary gonadotropins that drive steroid production in the gonads. However, the mechanisms underlying synchronization of GnRH1 neurons are unknown. Control of synchronicity by gap junctions between GnRH1 neurons has been proposed but not previously found. We recorded simultaneously from pairs of transgenically labeled GnRH1 neurons in adult male Astatotilapia burtoni cichlid fish. We report that GnRH1 neurons are strongly and uniformly interconnected by electrical synapses that can drive spiking in connected cells and can be reversibly blocked by meclofenamic acid. Our results suggest that electrical synapses could promote coordinated spike firing in a cellular assemblage of GnRH1 neurons to produce the pulsatile output necessary for activation of the pituitary and reproduction. PMID:25775522

  9. Structural Diversity in the Inner Ear of Teleost Fishes: Implications for Connections to the Mauthner Cell

    NASA Technical Reports Server (NTRS)

    Popper, Arthur N.; Edds-Walton, Peggy L.

    1995-01-01

    A body of literature suggests that the Mauthner cell startle response can be elicited by stimulation of the ear. While we know that there are projections to the M-cell from the ear, the specific endorgan(s) of the ear projecting to the M-cell are not known. Moreover, there are many reasons to question whether there is one pattern of inner ear to M-cell connection or whether the endorgan(s) projection to the M-cell varies in species that have different hearing capabilities of hearing structures. In this paper, we briefly review the structure of fish ears, with an emphasis on structural regionalization within the ear. We also review the central projections of the ear, along with a discussion of the limited data on projections to the M-cell.

  10. The cold-water connection: Bergmann's rule in North American freshwater fishes.

    PubMed

    Rypel, Andrew L

    2014-01-01

    Understanding general rules governing macroecological body size variations is one of the oldest pursuits in ecology. However, this science has been dominated by studies of terrestrial vertebrates, spurring debate over the validity of such rules in other taxonomic groups. Here, relationships between maximum body size and latitude, temperature, and elevation were evaluated for 29 North American freshwater fish species. Bergmann's rule (i.e., that body size correlates positively with latitude and negatively with temperature) was observed in 38% of species, converse Bergmann's rule (that body size correlates negatively with latitude and positively with temperature) was observed in 34% of species, and 28% of species showed no macroecological body size relationships. Most notably, every species that expressed Bergmann's rule was a cool- or cold-water species while every species that expressed converse Bergmann's rule was a warm-water species, highlighting how these patterns are likely connected to species thermal niches. This study contradicts previous research suggesting Bergmann's rule does not apply to freshwater fishes, and is congruent with an emerging paradigm of variable macroecological body size patterns in poikilotherms. PMID:24334744

  11. Variation in local abundance and species richness of stream fishes in relation to dispersal barriers: Implications for management and conservation

    USGS Publications Warehouse

    Nislow, K.H.; Hudy, M.; Letcher, B.H.; Smith, E.P.

    2011-01-01

    1.Barriers to immigration, all else being equal, should in principle depress local abundance and reduce local species richness. These issues are particularly relevant to stream-dwelling species when improperly designed road crossings act as barriers to migration with potential impacts on the viability of upstream populations. However, because abundance and richness are highly spatially and temporally heterogeneous and the relative importance of immigration on demography is uncertain, population- and community-level effects can be difficult to detect. 2.In this study, we tested the effects of potential barriers to upstream movements on the local abundance and species richness of a diverse assemblage of resident stream fishes in the Monongahela National Forest, West Virginia, U.S.A. Fishes were sampled using simple standard techniques above- and below road crossings that were either likely or unlikely to be barriers to upstream fish movements (based on physical dimensions of the crossing). We predicted that abundance of resident fishes would be lower in the upstream sections of streams with predicted impassable barriers, that the strength of the effect would vary among species and that variable effects on abundance would translate into lower species richness. 3.Supporting these predictions, the statistical model that best accounted for variation in abundance and species richness included a significant interaction between location (upstream or downstream of crossing) and type (passable or impassable crossing). Stream sections located above predicated impassable culverts had fewer than half the number of species and less than half the total fish abundance, while stream sections above and below passable culverts had essentially equivalent richness and abundance. 4.Our results are consistent with the importance of immigration and population connectivity to local abundance and species richness of stream fishes. In turn, these results suggest that when measured at

  12. Connectivity and Dispersal Patterns of Protected Biogenic Reefs: Implications for the Conservation of Modiolus modiolus (L.) in the Irish Sea.

    PubMed

    Gormley, Kate; Mackenzie, Clara; Robins, Peter; Coscia, Ilaria; Cassidy, Andrew; James, Jenny; Hull, Angela; Piertney, Stuart; Sanderson, William; Porter, Joanne

    2015-01-01

    Biogenic reefs created by Modiolus modiolus (Linnaeus, 1758) (horse mussel reefs) are marine habitats which support high levels of species biodiversity and provide valuable ecosystem services. Currently, M. modiolus reefs are listed as a threatened and/or declining species and habitat in all OSPAR regions and thus are highlighted as a conservation priority under the EU Marine Strategy Framework Directive (MSFD). Determining patterns of larval dispersal and genetic connectivity of remaining horse mussel populations can inform management efforts and is a critical component of effective marine spatial planning (MSP). Larval dispersal patterns and genetic structure were determined for several M. modiolus bed populations in the Irish Sea including those in Wales (North Pen Llŷn), Isle of Man (Point of Ayre) and Northern Ireland (Ards Peninsula and Strangford Lough). Simulations of larval dispersal suggested extant connectivity between populations within the Irish Sea. Results from the genetic analysis carried out using newly developed microsatellite DNA markers were consistent with those of the biophysical model. Results indicated moderately significant differentiation between the Northern Ireland populations and those in the Isle of Man and Wales. Simulations of larval dispersal over a 30 day pelagic larval duration (PLD) suggest that connectivity over a spatial scale of 150km is possible between some source and sink populations. However, it appears unlikely that larvae from Northern Ireland will connect directly with sites on the Llŷn or Isle of Man. It also appears unlikely that larvae from the Llŷn connect directly to any of the other sites. Taken together the data establishes a baseline for underpinning management and conservation of these important and threatened marine habitats in the southern part of the known range. PMID:26625263

  13. Connectivity and Dispersal Patterns of Protected Biogenic Reefs: Implications for the Conservation of Modiolus modiolus (L.) in the Irish Sea

    PubMed Central

    Gormley, Kate; Mackenzie, Clara; Robins, Peter; Coscia, Ilaria; Cassidy, Andrew; James, Jenny; Hull, Angela; Piertney, Stuart; Sanderson, William; Porter, Joanne

    2015-01-01

    Biogenic reefs created by Modiolus modiolus (Linnaeus, 1758) (horse mussel reefs) are marine habitats which support high levels of species biodiversity and provide valuable ecosystem services. Currently, M. modiolus reefs are listed as a threatened and/or declining species and habitat in all OSPAR regions and thus are highlighted as a conservation priority under the EU Marine Strategy Framework Directive (MSFD). Determining patterns of larval dispersal and genetic connectivity of remaining horse mussel populations can inform management efforts and is a critical component of effective marine spatial planning (MSP). Larval dispersal patterns and genetic structure were determined for several M. modiolus bed populations in the Irish Sea including those in Wales (North Pen Llŷn), Isle of Man (Point of Ayre) and Northern Ireland (Ards Peninsula and Strangford Lough). Simulations of larval dispersal suggested extant connectivity between populations within the Irish Sea. Results from the genetic analysis carried out using newly developed microsatellite DNA markers were consistent with those of the biophysical model. Results indicated moderately significant differentiation between the Northern Ireland populations and those in the Isle of Man and Wales. Simulations of larval dispersal over a 30 day pelagic larval duration (PLD) suggest that connectivity over a spatial scale of 150km is possible between some source and sink populations. However, it appears unlikely that larvae from Northern Ireland will connect directly with sites on the Llŷn or Isle of Man. It also appears unlikely that larvae from the Llŷn connect directly to any of the other sites. Taken together the data establishes a baseline for underpinning management and conservation of these important and threatened marine habitats in the southern part of the known range. PMID:26625263

  14. Okeanos Explorer 2014 Gulf of Mexico Expedition: engaging and connecting with diverse and geographically dispersed audiences

    NASA Astrophysics Data System (ADS)

    Russell, C. W.; Elliott, K.; Lobecker, E.; McKenna, L.; Haynes, S.; Crum, E.; Gorell, F.

    2014-12-01

    From February to May 2014, NOAA Ship Okeanos Explorer conducted a telepresence-enabled ocean exploration expedition addressing NOAA and National deepwater priorities in the U.S. Gulf of Mexico. The community-driven expedition connected diverse and geographically dispersed audiences including scientists from industry, academia, and government, and educators, students, and the general public. Expedition planning included input from the ocean science and management community, and was executed with more than 70 scientists and students from 14 U.S. states participating from shore in real time. Training the next generation permeated operations: a mapping internship program trained undergraduate and graduate students; an ROV mentorship program trained young engineers to design, build and operate the system; and undergraduate through doctoral students around the country collaborated with expedition scientists via telepresence. Online coverage of the expedition included background materials, daily updates, and mission logs that received more than 100,000 visits by the public. Live video feeds of operations received more than 700,000 views online. Additionally, professional development workshops hosted in multiple locations throughout the spring introduced educators to the Okeanos Explorer Educational Materials Collection and the live expedition, and taught them how to use the website and education resources in their classrooms. Social media furthered the reach of the expedition to new audiences, garnered thousands of new followers and provided another medium for real-time interactions with the general public. Outreach continued through live interactions with museums and aquariums, Exploration Command Center tours, outreach conducted by partners, and media coverage in more than 190 outlets in the U.S. and Europe. Ship tours were conducted when the ship came in to port to engage local scientists, ocean managers, and educators. After the expedition, data and products were

  15. Local connected fractal dimension analysis in gill of fish experimentally exposed to toxicants.

    PubMed

    Manera, Maurizio; Giari, Luisa; De Pasquale, Joseph A; Sayyaf Dezfuli, Bahram

    2016-06-01

    An operator-neutral method was implemented to objectively assess European seabass, Dicentrarchus labrax (Linnaeus, 1758) gill pathology after experimental exposure to cadmium (Cd) and terbuthylazine (TBA) for 24 and 48h. An algorithm-derived local connected fractal dimension (LCFD) frequency measure was used in this comparative analysis. Canonical variates (CVA) and linear discriminant analysis (LDA) were used to evaluate the discrimination power of the method among exposure classes (unexposed, Cd exposed, TBA exposed). Misclassification, sensitivity and specificity, both with original and cross-validated cases, were determined. LCFDs frequencies enhanced the differences among classes which were visually selected after their means, respective variances and the differences between Cd and TBA exposed means, with respect to unexposed mean, were analyzed by scatter plots. Selected frequencies were then scanned by means of LDA, stepwise analysis, and Mahalanobis distance to detect the most discriminative frequencies out of ten originally selected. Discrimination resulted in 91.7% of cross-validated cases correctly classified (22 out of 24 total cases), with sensitivity and specificity, respectively, of 95.5% (1 false negative with respect to 21 really positive cases) and 75% (1 false positive with respect to 3 really negative cases). CVA with convex hull polygons ensured prompt, visually intuitive discrimination among exposure classes and graphically supported the false positive case. The combined use of semithin sections, which enhanced the visual evaluation of the overall lamellar structure; of LCFD analysis, which objectively detected local variation in complexity, without the possible bias connected to human personnel; and of CVA/LDA, could be an objective, sensitive and specific approach to study fish gill lamellar pathology. Furthermore this approach enabled discrimination with sufficient confidence between exposure classes or pathological states and avoided

  16. Habitat- and bay-scale connectivity of sympatric fishes in an estuarine nursery

    NASA Astrophysics Data System (ADS)

    Dance, Michael A.; Rooker, Jay R.

    2015-12-01

    Acoustic telemetry was used to examine habitat- and bay-scale connectivity for co-occurring juvenile fishes, southern flounder (Paralichthys lethostigma) and red drum (Sciaenops ocellatus), at two spatial scales in a model estuarine seascape. An acoustic positioning system was deployed to examine habitat-scale (ca. 1 m-1 km) movement, while a larger gridded array was deployed to examine bay-scale movement (ca. 1-20 km). Both species exhibited greater use of edge habitat and seagrass beds at the habitat scale; however, rates of movement within habitats varied between species. Southern flounder movement (mean = 4.0 m min-1) increased with decreasing habitat complexity (seagrass to bare sand) and increasing temperature, while red drum rate of movement (mean = 8.4 m min-1) was not significantly affected by environmental factors at the habitat scale, indicating the use of different foraging strategies (i.e. ambush vs. active). Bay-scale distribution was influenced by physicochemical conditions and seascape composition, with both species found most frequently in areas with high seagrass coverage and relative close proximity to tidal creeks and connective channels. Response to environmental variables often differed between species and the probability of bay-scale movement (>1 km) for southern flounder was greatest on days with narrow tidal ranges (<0.4 m) and higher temperatures (>17 °C), while the probability of bay-scale movement for red drum increased in response to decreasing salinity and lower temperatures (<16 °C). Species-specific variation in movement patterns within and across habitat types observed here at both the habitat and bay scale suggest sympatric species employ different strategies to partition resources within estuarine nursery areas and highlight the importance of multi-species assessments for improving our understanding of habitat value and ecosystem function.

  17. Modeling larval connectivity of the Atlantic surfclams within the Middle Atlantic Bight: Model development, larval dispersal and metapopulation connectivity

    NASA Astrophysics Data System (ADS)

    Zhang, Xinzhong; Haidvogel, Dale; Munroe, Daphne; Powell, Eric N.; Klinck, John; Mann, Roger; Castruccio, Frederic S.

    2015-02-01

    To study the primary larval transport pathways and inter-population connectivity patterns of the Atlantic surfclam, Spisula solidissima, a coupled modeling system combining a physical circulation model of the Middle Atlantic Bight (MAB), Georges Bank (GBK) and the Gulf of Maine (GoM), and an individual-based surfclam larval model was implemented, validated and applied. Model validation shows that the model can reproduce the observed physical circulation patterns and surface and bottom water temperature, and recreates the observed distributions of surfclam larvae during upwelling and downwelling events. The model results show a typical along-shore connectivity pattern from the northeast to the southwest among the surfclam populations distributed from Georges Bank west and south along the MAB shelf. Continuous surfclam larval input into regions off Delmarva (DMV) and New Jersey (NJ) suggests that insufficient larval supply is unlikely to be the factor causing the failure of the population to recover after the observed decline of the surfclam populations in DMV and NJ from 1997 to 2005. The GBK surfclam population is relatively more isolated than populations to the west and south in the MAB; model results suggest substantial inter-population connectivity from southern New England to the Delmarva region. Simulated surfclam larvae generally drift for over one hundred kilometers along the shelf, but the distance traveled is highly variable in space and over time. Surfclam larval growth and transport are strongly impacted by the physical environment. This suggests the need to further examine how the interaction between environment, behavior, and physiology affects inter-population connectivity. Larval vertical swimming and sinking behaviors have a significant net effect of increasing larval drifting distances when compared with a purely passive model, confirming the need to include larval behavior.

  18. Using dense locality sampling resolves the subtle genetic population structure of the dispersive fish species Plecoglossus altivelis.

    PubMed

    Takeshima, Hirohiko; Iguchi, Kei'ichiro; Hashiguchi, Yasuyuki; Nishida, Mutsumi

    2016-07-01

    In dispersive species with continuous distributions, genetic differentiation between local populations is often absent or subtle and thus difficult to detect. To incorporate such subtle differentiation into management plans, it may be essential to analyse many samples from many localities using adequate numbers of high-resolution genetic markers. Here, we evaluated the usefulness of dense locality sampling in resolving genetic population structure in the ayu (Plecoglossus altivelis), a dispersive fish important in Japanese inland fisheries. Genetic variability in, and differentiation between, ayu populations around the Japan-Ryukyu Archipelago were investigated in 4746 individuals collected from 120 localities by genotyping 12 microsatellite markers. These individuals represented the two subspecies of ayu, namely the Ryukyuan subspecies (Plecoglossus altivelis ryukyuensis) and both amphidromous and landlocked forms of the nominotypical subspecies (P. a. altivelis) along the archipelago. We successfully detected an absence of genetic differentiation within the landlocked form and subtle but significant differentiation and clear geographic patterns of genetic variation among populations of the amphidromous form, which had been considered genetically homogeneous. This suggests that dense locality sampling effectively resolves subtle differences in genetic population structure, reducing stochastic deviation in the detection of genetic differentiation and geographic patterns in local populations of this dispersive species. Resampling analyses based on empirical data sets clearly demonstrate the effectiveness of increasing the number of locality samples for stable and reliable estimations of genetic fixation indices. The genetic population structure observed within the amphidromous form provides useful information for identifying management or conservation units in ayu. PMID:27085501

  19. Invasive zebra mussels (Driessena polymorpha) and Asian clams (Corbicula fluminea) survive gut passage of migratory fish species: implications for dispersal

    USGS Publications Warehouse

    Gatlin, Michael R.; Shoup, Daniel E.; Long, James M.

    2013-01-01

    The introduction and spread of invasive species is of great concern to natural resource managers in the United States. To effectively control the spread of these species, managers must be aware of the multitude of dispersal methods used by the organisms. We investigated the potential for survival through the gut of a migrating fish (blue catfish, Ictalurus furcatus) as a dispersal mechanism for two invasive bivalves: zebra mussel (Driessena polymorpha) and Asian clam (Corbicula fluminea). Blue catfish (N = 62) were sampled over several months from Sooner Lake, Oklahoma, transported to a laboratory and held in individual tanks for 48 h. All fecal material was collected and inspected for live mussels. Survival was significantly related to water temperature in the lake at the time of collection, with no mussels surviving above 21.1 C°, whereas 12 % of zebra mussels (N = 939) and 39 % of Asian clams (N = 408) consumed in cooler water survived gut passage. This research demonstrates the potential for blue catfish to serve as a dispersal vector for invasive bivalves at low water temperatures.

  20. Vocal-Motor and Auditory Connectivity of the Midbrain Periaqueductal Gray in a Teleost Fish

    PubMed Central

    Kittelberger, J. Matthew; Bass, Andrew H.

    2012-01-01

    The midbrain periaqueductal gray (PAG) plays a central role in the descending control of vocalization across vertebrates. The PAG has also been implicated in auditory-vocal integration, though its precise role in such integration remains largely unexplored. Courtship and territorial interactions in plainfin midshipman fish depend on vocal communication, and the PAG is a central component of the midshipman vocal-motor system. We made focal neurobiotin injections into the midshipman PAG to both map its auditory-vocal circuitry and enable evolutionary comparisons with tetrapod vertebrates. These injections revealed an extensive bidirectional pattern of connectivity between the PAG and known sites in both the descending vocal-motor and ascending auditory systems, including portions of the telencephalon, dorsal thalamus, hypothalamus, posterior tuberculum, midbrain and hindbrain. Injections in the medial PAG produced dense label within hindbrain auditory nuclei, while those confined to the lateral PAG preferentially labeled hypothalamic and midbrain auditory areas. Thus, the teleost PAG may have functional subdivisions playing different roles in vocal-auditory integration. Together, the results confirm several pathways previously identified by injections into known auditory or vocal areas and provide strong support for the hypothesis that the teleost PAG is centrally involved in auditory-vocal integration. PMID:22826153

  1. Vocal-motor and auditory connectivity of the midbrain periaqueductal gray in a teleost fish.

    PubMed

    Kittelberger, J Matthew; Bass, Andrew H

    2013-03-01

    The midbrain periaqueductal gray (PAG) plays a central role in the descending control of vocalization across vertebrates. The PAG has also been implicated in auditory-vocal integration, although its precise role in such integration remains largely unexplored. Courtship and territorial interactions in plainfin midshipman fish depend on vocal communication, and the PAG is a central component of the midshipman vocal-motor system. We made focal neurobiotin injections into the midshipman PAG to both map its auditory-vocal circuitry and allow evolutionary comparisons with tetrapod vertebrates. These injections revealed an extensive bidirectional pattern of connectivity between the PAG and known sites in both the descending vocal-motor and the ascending auditory systems, including portions of the telencephalon, dorsal thalamus, hypothalamus, posterior tuberculum, midbrain, and hindbrain. Injections in the medial PAG produced dense label within hindbrain auditory nuclei, whereas those confined to the lateral PAG preferentially labeled hypothalamic and midbrain auditory areas. Thus, the teleost PAG may have functional subdivisions playing different roles in vocal-auditory integration. Together the results confirm several pathways previously identified by injections into known auditory or vocal areas and provide strong support for the hypothesis that the teleost PAG is centrally involved in auditory-vocal integration. PMID:22826153

  2. Direct determination of fatty acids in fish tissues: quantifying top predator trophic connections.

    PubMed

    Parrish, Christopher C; Nichols, Peter D; Pethybridge, Heidi; Young, Jock W

    2015-01-01

    Fatty acids are a valuable tool in ecological studies because of the large number of unique structures synthesized. They provide versatile signatures that are being increasingly employed to delineate the transfer of dietary material through marine and terrestrial food webs. The standard procedure for determining fatty acids generally involves lipid extraction followed by methanolysis to produce methyl esters for analysis by gas chromatography. By directly transmethylating ~50 mg wet samples and adding an internal standard it was possible to greatly simplify the analytical methodology to enable rapid throughput of 20-40 fish tissue fatty acid analyses a day including instrumental analysis. This method was verified against the more traditional lipid methods using albacore tuna and great white shark muscle and liver samples, and it was shown to provide an estimate of sample dry mass, total lipid content, and a condition index. When large fatty acid data sets are generated in this way, multidimensional scaling, analysis of similarities, and similarity of percentages analysis can be used to define trophic connections among samples and to quantify them. These routines were used on albacore and skipjack tuna fatty acid data obtained by direct methylation coupled with literature values for krill. There were clear differences in fatty acid profiles among the species as well as spatial differences among albacore tuna sampled from different locations. PMID:25376156

  3. Modeling larval dispersal and quantifying coastal connectivity based on a downscaling ocean model in Seto Inland Sea, Japan

    NASA Astrophysics Data System (ADS)

    Kosako, T.; Uchiyama, Y.; Mitarai, S.

    2014-12-01

    Connectivity is defined as the probability that particles leaving a source patch (spawning site) arrive at a sink patch (settling ground) for a given advection time. It can measure stochastic processes of a wide range of larval dispersal due to chaotic coastal circulations (e.g., Mitarai et al., 2009). The present study aims at investigating larval networks in Seto Inland Sea (SIS), an about 450-km long, semi-enclosed, estuarine tidal channel connected to Kuroshio drifting off the two openings of SIS. We quantify coastal connectivity using Lagrangian PDFs of enormous amount of Lagrangian particles released in the modeled SIS circulation field in a double nested configuration based on ROMS at the horizontal grid spacing of 600 m (Uchiyama et al., 2012). The particles are released twice a day from 140 source patches with a radius of 5 km for 2 months in the winter 2011, and integrated over the advection time of 30 days, mimicking spawning and pelagic larvae of marbled sole. The Lagrangian PDFs and the associated connectivity patterns are found to be generally heterogeneous. The connectivity matrices successively depict the larval networks in SIS. We separate SIS into 8 subregions (i.e., bays) to determine the networks among them. The fraction of the particles that exit to another region is about less than 40% except for the two entrance subregions, suggesting the intra-subregional transport is predominant. However, the particles are gradually transported eastward due to the residual mean clockwise circulation of SIS. We then evaluate the larval dispersal of marbled sole in a subregion, Harima Nada (HN). Destination strength shows that particles released in HN are mainly transported towards the northern shore of Shodo Island, and source strength indicates that the particles arriving there originate primarily from the western shore of HN. Those results suggest a potential utility of the ocean model-derived connectivity to quantify the larval networks in estuaries.

  4. Luminous Enteric Bacteria of Marine Fishes: a Study of Their Distribution, Densities, and Dispersion

    PubMed Central

    Ruby, E. G.; Morin, J. G.

    1979-01-01

    Three taxa of luminous bacteria (Photobacterium fischeri, P. phosphoreum, and Beneckea spp.) were found in the enteric microbial populations of 22 species of surface- and midwater-dwelling fishes. These bacteria often occurred in concentrations ranging between 105 and 107 colony-forming units per ml of enteric contents. By using a genetically marked strain, it was determined that luminous cells entering the fish during ingestion of seawater or contaminated particles traversed the alimentary tract and survived the digestive processes. After excretion, luminous bacteria proliferated extensively on the fecal material and became distributed into the surrounding seawater. Thus, this enteric habitat may serve as an enrichment of viable cells entering the planktonic luminous population. PMID:16345429

  5. Assessment of dissolved nutrients dispersal derived from offshore fish-farm using nitrogen stable isotope ratios (δ 15N) in macroalgal bioassays

    NASA Astrophysics Data System (ADS)

    García-Sanz, T.; Ruiz, J. M.; Pérez, M.; Ruiz, M.

    2011-02-01

    In this study, the dispersal of wastes from offshore fish farms was evaluated by analyzing nitrogen stable isotope ratios (δ 15N) in macroalgae incubated in the water column at sites located at an increasing distance from the fish cages. Bioassays were performed at three fish farms situated in separate localities with different nutritional conditions (Canary Islands, Murcia and Catalonia) and varying in size, species of fish reared and annual production. Macroalgal bioassays were carried out in two different directions (DI and DII) and they were replicated at each distance in order to evaluate the effect of small-scale variability on the spatial extent of fish farm wastes. The results obtained with δ 15N contribute to a better understanding of the application of nitrogen stable isotopes ratios in macroalgae as an effective bioindicator for tracing the dispersion of offshore fish farm wastes, and demonstrate that fish farm wastes can be traced even over distances of some km from the pollution source. In the Canary Islands, the maximum distance obtained for detection of fish farm wastes was between 450 and 700 m. Of the three installations studied, Murcia presented the greatest distance for detection of fish farm waste influence, ranging from between 1550 and 2450 m, whilst in Catalonia this distance was less than 120 m. In Catalonia, the results were masked by the influence of other sources of nitrogen, and thus fish farm wastes were detected at more reduced distances than expected. These results confirm that fish farm wastes can be traced using the nitrogen stable isotope ratios of macroalgae and that this method can also be useful for identifying areas of potential risk to some sensitive ecosystems, and as an early signal that changes in the community structure might occur.

  6. MODELING SCALE-DEPENDENT LANDSCAPE PATTERN, DISPERSAL, AND CONNECTIVITY FROM THE PERSPECTIVE OF THE ORGANISM

    EPA Science Inventory

    Effects of fine- to broad-scale patterns of landscape heterogeneity on dispersal success were examined for organisms varying in life history traits. To systematically control spatial pattern, a landscape model was created by merging physiographically-based maps of simulated land...

  7. An innovative dispersant with very low toxicity and bio-accumulation, the experiment at the Ayia Napa fishing shelter in Cyprus

    NASA Astrophysics Data System (ADS)

    Theodorou, Paraskevas

    2016-04-01

    The application of chemical dispersants can be an effective mean for oil spill response strategy. The dispersion of oil by chemical dispersants accelerates evaporation and disperse the oil into the water column, where it is broken down by natural processes resulting to the reduction of environmental and economic impacts of the spilled oil, especially at near coastal resources. However, as with other response techniques, dispersants have also their limitations and account must be taken of the characteristics of the oil being treated (efficiency), water and weather conditions and environmental sensitivities (toxicity and bioaccumulation). The MSL dispersant is an innovative new and its composition is mainly based on natural constituents. MSL dispersant has a number of advantages compared to other dispersants: -Efficiency is more than 80% when using the Arabian crude oil. -Toxicity is in the range of 200 -600ppm, depending on the species used for testing. -Very high biodegradation rate. Due to the above characteristics MSL dispersant can be used also for the cleaning and to maintain the good environmental condition of harbor, ports, rivers, canals contaminated from Petroleum Hydrocarbons. The MSL dispersant has been tested during a period of 2 months in the fishing shelter of Ayia Napa in Cyprus with excellent results. Water samples taken in the fishing shelter before the experiment shown high concentration for 6 chemical parameters (BOD5, COD, FOG, TKN, TP, TPH), while after the use of the and MSL dispersant their concentration was reduced drastically, for some of the parameters down to the limits of the chemical analysis. The experiment was repeated every 2 weeks for a period of 2 weeks.

  8. Weak genetic structure indicates strong dispersal limits: a tale of two coral reef fish

    PubMed Central

    Purcell, John F.H; Cowen, Robert K; Hughes, Colin R; Williams, Dean A

    2006-01-01

    The extent of dispersal by pelagic larvae in marine environments, including coral reefs, is central for understanding local population dynamics and designing sustainable marine reserves. We present here the first example of a clear stepping-stone genetic structure throughout the Caribbean basin for a common coral reef species, the French grunt (Haemulon flavolineatum). Analysis of microsatellite DNA markers indicated that French grunt population structure may be characterized by overlapping populations throughout the Caribbean, influenced by independent population dynamics but with no fixed geographical boundaries. In addition, different spatial genetic patterns were found in different oceanographic regions. A second species, the bluehead wrasse (Thalassoma bifasciatum), has a much longer pelagic larval duration than French grunts and showed no explicit spatial pattern of genetic variation. This finding is concordant with the hypothesis of a positive relationship between larval dispersal and duration in the plankton. While the magnitude of the genetic signal of population structure in French grunts was very low (FST≈0.003), the pattern of isolation-by-distance throughout the Caribbean indicated considerable population structure with important ecological and conservation significance. PMID:16777742

  9. Population Connectivity and Phylogeography of a Coastal Fish, Atractoscion aequidens (Sciaenidae), across the Benguela Current Region: Evidence of an Ancient Vicariant Event

    PubMed Central

    Henriques, Romina; Potts, Warren M.; Santos, Carmen V.; Sauer, Warwick H. H.; Shaw, Paul W.

    2014-01-01

    Contemporary patterns of genetic diversity and population connectivity within species can be influenced by both historical and contemporary barriers to gene flow. In the marine environment, present day oceanographic features such as currents, fronts and upwelling systems can influence dispersal of eggs/larvae and/juveniles/adults, shaping population substructuring. The Benguela Current system in the southeastern Atlantic is one of the oldest upwelling systems in the world, and provides a unique opportunity to investigate the relative influence of contemporary and historical mechanisms shaping the evolutionary history of warm-temperate fish species. Using the genetic variation in the mitochondrial DNA Control Region and eight nuclear microsatellite DNA loci, we identified the presence of two highly divergent populations in a vagile and warm-temperate fish species, Atractoscion aequidens, across the Benguela region. The geographical distributions of the two populations, on either side of the perennial upwelling cell, suggest a strong correlation between the oceanographic features of the system and the breakdown of gene flow within this species. Genetic divergence (mtDNA φST = 0.902, microsatellite FST = 0.055: probability of genetic homogeneity for either marker = p<0.001), absence of migrants (less than 1% per generation) between populations and coalescent estimates of time since most recent common ancestor suggest that the establishment of the main oceanographic features of the system (2 million years ago), particularly the strengthening and position of the perennial upwelling cell, is the most likely mechanism behind the observed isolation. Concordance between mitochondrial and nuclear genetic markers indicates that isolation and divergence of the northern and southern Benguela populations of A. aequidens occurred deep in the past and has continued to the present day. These findings suggest that the Benguela Current system may constitute an ancient

  10. Commercial catfish pond water color and fish-eating birds: What is the connection?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was designed to test and predict fish-eating bird use and avoidance at catfish production ponds during 2 winters in Arkansas. We measured (1) physical (size, length, width, depth, surface condition, secchi depth), (2) biological (fish size and stocking density, algal species composition ...

  11. Connecting ground water influxes with fish species diversity in an urbanized watershed

    USGS Publications Warehouse

    Steffy, L.Y.; McGinty, A.L.; Welty, C.; Kilham, S.S.

    2004-01-01

    Valley Creek watershed is a small stream system that feeds the Schuylkill River near Philadelphia, Pennsylvania. The watershed is highly urbanized, including over 17 percent impervious surface cover (ISC) by area. Imperviousness in a watershed has been linked to fish community structure and integrity. Generally, above 10 to 12 percent ISC there is marked decline in fish assemblages with fish being absent above 25 percent ISC. This study quantifies the importance of ground water in maintaining fish species diversity in subbasins with over 30 percent ISC. Valley Creek contains an atypical fish assemblage in that the majority of the fish are warm-water species, and the stream supports naturally reproducing brown trout, which were introduced and stocked from the early 1900s to 1985. Fish communities were quantified at 13 stations throughout the watershed, and Simpson's species diversity index was calculated. One hundred and nine springs were located, and their flow rates measured. A cross covariance analysis between Simpson's species diversity index and spring flow rates upstream of fish stations was performed to quantify the spatial correlation between these two variables. The correlation was found to be highest at lag distances up to about 400 m and drop off significantly beyond lag distances of about 800 m.

  12. Assessing distribution of migratory fishes and connectivity following complete and partial dam removals in a North Carolina River

    USGS Publications Warehouse

    Raabe, Joshua K.; Hightower, Joseph E.

    2014-01-01

    Fish, especially migratory species, are assumed to benefit from dam removals that restore connectivity and access to upstream habitat, but few studies have evaluated this assumption. Therefore, we assessed the movement of migratory fishes in the springs of 2008 through 2010 and surveyed available habitat in the Little River, North Carolina, a tributary to the Neuse River, after three complete dam removals and one partial (notched) dam removal. We tagged migratory fishes with PIT tags at a resistance-board weir located at a dam removal site (river kilometer [rkm] 3.7) and followed their movements with an array of PIT antennas. The river-wide distribution of fish following removals varied by species. For example, 24–31% of anadromous American Shad Alosa sapidissima, 45–49% of resident Gizzard Shad Dorosoma cepedianum, and 4–11% of nonnative Flathead CatfishPylodictis olivaris passed the dam removal site at rkm 56 in 2009 and 2010. No preremoval data were available for comparison, but reach connectivity appeared to increase as tagged individuals passed former dam sites and certain individuals moved extensively both upstream and downstream. However, 17–28% did not pass the partially removed dam at rkm 7.9, while 20–39% of those that passed remained downstream for more than a day before migrating upstream. Gizzard Shad required the deepest water to pass this notched structure, followed by American Shad then Flathead Catfish. Fish that passed the notched dam accessed more complex habitat (e.g., available substrate size-classes) in the middle and upper reaches. The results provide strong support for efforts to restore currently inaccessible habitat through complete removal of derelict dams.

  13. Examination of circulation, dispersion, and connectivity in Lunenburg Bay of Nova Scotia using a nested-grid circulation model

    NASA Astrophysics Data System (ADS)

    Sheng, Jinyu; Zhao, Jun; Zhai, Li

    2009-05-01

    A coastal ocean observatory has been established in Lunenburg Bay, Nova Scotia since summer 2002 as part of a multi-agency research program of marine environmental observation and prediction over Atlantic Canada coastal waters. The observatory was operational when a category-2 hurricane (Juan) made land fall within 50-km of the bay in September 2003. The coastal response of the bay to Hurricane Juan is examined using a nested-grid coastal circulation modelling system. The nested-grid system is forced by the local wind, tides, and remotely generated coastal waves. A comparison of model results with observed surface elevations and currents demonstrates that the nested-grid system has reasonable skills in simulating the three-dimensional (3D) storm-induced circulation in the study region. The 3D model currents are used to examine the transport and dispersion of passive tracers, local flushing time, and retention and connectivity of passive particles in the bay during Hurricane Juan. Numerical results demonstrate that local wind forcing plays a dominant role in generating large dispersion and hydrodynamic connectivity in the bay during the storm.

  14. Importance of floodplain connectivity to fish populations in the Apalachicola River, Florida

    USGS Publications Warehouse

    Burgess, O.T.; Pine, William E., III; Walsh, S.J.

    2013-01-01

    Floodplain habitats provide critical spawning and rearing habitats for many large-river fishes. The paradigm that floodplains are essential habitats is often a key reason for restoring altered rivers to natural flow regimes. However, few studies have documented spatial and temporal utilization of floodplain habitats by adult fish of sport or commercial management interest or assessed obligatory access to floodplain habitats for species' persistence. In this study, we applied telemetry techniques to examine adult fish movements between floodplain and mainstem habitats, paired with intensive light trap sampling of larval fish in these same habitats, to assess the relationships between riverine flows and fish movement and spawning patterns in restored and unmodified floodplain distributaries of the Apalachicola River, Florida. Our intent is to inform resource managers on the relationships between the timing, magnitude and duration of flow events and fish spawning as part of river management actions. Our results demonstrate spawning by all study species in floodplain and mainstem river habitat types, apparent migratory movements of some species between these habitats, and distinct spawning events for each study species on the basis of fish movement patterns and light trap catches. Additionally, Micropterus spp., Lepomis spp. and, to a lesser degree, Minytrema melanops used floodplain channel habitat that was experimentally reconnected to the mainstem within a few weeks of completing the restoration. This result is of interest to managers assessing restoration activities to reconnect these habitats as part of riverine restoration programmes globally.

  15. Fish assemblages of the Casiquiare River, a corridor and zoogeographical filter for dispersal between the Orinoco and Amazon basins

    USGS Publications Warehouse

    Winemiller, K.O.; Lopez-Fernandez, H.; Taphorn, D.C.; Nico, L.G.; Duque, A.B.

    2008-01-01

    Aim: The aim of this study was to determine whether the Casiquiare River functions as a free dispersal corridor or as a partial barrier (i.e. filter) for the interchange of fish species of the Orinoco and Negro/Amazon basins using species assemblage patterns according to geographical location and environmental features. Location: The Casiquiare, Upper Orinoco and Upper Negro rivers in southern Venezuela, South America. Methods: Our study was based on an analysis of species presence/absence data and environmental information (11 habitat characteristics) collected by the authors and colleagues between the years 1984 and 1999. The data set consisted of 269 sampled sites and 452 fish species (> 50,000 specimens). A wide range of habitat types was included in the samples, and the collection sites were located at various points along the entire length of the Casiquiare main channel, at multiple sites on its tributary streams, as well as at various nearby sites outside the Casiquiare drainage, within the Upper Orinoco and Upper Rio Negro river systems. Most specimens and field data used in this analysis are archived in the Museo de Ciencias Naturales in Guanare, Venezuela. We performed canonical correspondence analysis (CCA) based on species presence/absence using two versions of the data set: one that eliminated sites having < 5 species and species occurring at < 5 sites; and another that eliminated sites having < 10 species and species occurring at < 10 sites. Cluster analysis was performed on sites based on species assemblage similarity, and a separate analysis was performed on species based on CCA loadings. Results: The CCA results for the two versions of the data set were qualitatively the same. The dominant environmental axis contrasted assemblages and sites associated with blackwater vs. clearwater conditions. Longitudinal position on the Casiquiare River was correlated (r2 = 0.33) with CCA axis-1 scores, reflecting clearwater conditions nearer to its origin

  16. Patterns, causes, and consequences of marine larval dispersal

    PubMed Central

    D’Aloia, Cassidy C.; Bogdanowicz, Steven M.; Francis, Robin K.; Majoris, John E.; Harrison, Richard G.; Buston, Peter M.

    2015-01-01

    Quantifying the probability of larval exchange among marine populations is key to predicting local population dynamics and optimizing networks of marine protected areas. The pattern of connectivity among populations can be described by the measurement of a dispersal kernel. However, a statistically robust, empirical dispersal kernel has been lacking for any marine species. Here, we use genetic parentage analysis to quantify a dispersal kernel for the reef fish Elacatinus lori, demonstrating that dispersal declines exponentially with distance. The spatial scale of dispersal is an order of magnitude less than previous estimates—the median dispersal distance is just 1.7 km and no dispersal events exceed 16.4 km despite intensive sampling out to 30 km from source. Overlaid on this strong pattern is subtle spatial variation, but neither pelagic larval duration nor direction is associated with the probability of successful dispersal. Given the strong relationship between distance and dispersal, we show that distance-driven logistic models have strong power to predict dispersal probabilities. Moreover, connectivity matrices generated from these models are congruent with empirical estimates of spatial genetic structure, suggesting that the pattern of dispersal we uncovered reflects long-term patterns of gene flow. These results challenge assumptions regarding the spatial scale and presumed predictors of marine population connectivity. We conclude that if marine reserve networks aim to connect whole communities of fishes and conserve biodiversity broadly, then reserves that are close in space (<10 km) will accommodate those members of the community that are short-distance dispersers. PMID:26508628

  17. Historical abiotic events or human-aided dispersal: inferring the evolutionary history of a newly discovered galaxiid fish

    PubMed Central

    Chakona, Gamuchirai; Swartz, Ernst R; Chakona, Albert

    2015-01-01

    Range expansion of obligate freshwater fishes in the Cape Floristic Region (CFR) of South Africa has mostly been attributed to river capture events and confluence of rivers following sea-level regression. The role of low drainage divides and interbasin water transfers has received less attention. This study analyzed mitochondrial and nuclear DNA sequences to assess the processes that could have influenced the phylogeographic patterns of a newly discovered lineage of Galaxias zebratus (hereafter Galaxias zebratus “Joubertina”) that occurs across two currently isolated river systems close to the Joubertina area in the eastern CFR. Results from both analyses revealed that observed genetic differentiation cannot be explained by isolation between the two river systems. No genetic differentiation was found between the Krom River system and a population from one of the Gamtoos tributaries. Shallow genetic differentiation was found between the Krom and the other Gamtoos populations. Historical river capture events and sea-level changes do not explain the present distribution of Galaxias zebratus “Joubertina” across the Krom and Gamtoos River systems. Interbasin dispersal during pluvial periods, recent river capture, or recent human-mediated translocation seems to be the most plausible explanations. PMID:25897377

  18. Historical abiotic events or human-aided dispersal: inferring the evolutionary history of a newly discovered galaxiid fish.

    PubMed

    Chakona, Gamuchirai; Swartz, Ernst R; Chakona, Albert

    2015-04-01

    Range expansion of obligate freshwater fishes in the Cape Floristic Region (CFR) of South Africa has mostly been attributed to river capture events and confluence of rivers following sea-level regression. The role of low drainage divides and interbasin water transfers has received less attention. This study analyzed mitochondrial and nuclear DNA sequences to assess the processes that could have influenced the phylogeographic patterns of a newly discovered lineage of Galaxias zebratus (hereafter Galaxias zebratus "Joubertina") that occurs across two currently isolated river systems close to the Joubertina area in the eastern CFR. Results from both analyses revealed that observed genetic differentiation cannot be explained by isolation between the two river systems. No genetic differentiation was found between the Krom River system and a population from one of the Gamtoos tributaries. Shallow genetic differentiation was found between the Krom and the other Gamtoos populations. Historical river capture events and sea-level changes do not explain the present distribution of Galaxias zebratus "Joubertina" across the Krom and Gamtoos River systems. Interbasin dispersal during pluvial periods, recent river capture, or recent human-mediated translocation seems to be the most plausible explanations. PMID:25897377

  19. DNA and dispersal models highlight constrained connectivity in a migratory marine megavertebrate

    USGS Publications Warehouse

    Naro-Maciel, Eugenia; Hart, Kristen M.; Cruciata, Rossana; Putman, Nathan F.

    2016-01-01

    Population structure and spatial distribution are fundamentally important fields within ecology, evolution, and conservation biology. To investigate pan-Atlantic connectivity of globally endangered green turtles (Chelonia mydas) from two National Parks in Florida, USA, we applied a multidisciplinary approach comparing genetic analysis and ocean circulation modeling. The Everglades (EP) is a juvenile feeding ground, whereas the Dry Tortugas (DT) is used for courtship, breeding, and feeding by adults and juveniles. We sequenced two mitochondrial segments from 138 turtles sampled there from 2006-2015, and simulated oceanic transport to estimate their origins. Genetic and ocean connectivity data revealed northwestern Atlantic rookeries as the major natal sources, while southern and eastern Atlantic contributions were negligible. However, specific rookery estimates differed between genetic and ocean transport models. The combined analyses suggest that post-hatchling drift via ocean currents poorly explains the distribution of neritic juveniles and adults, but juvenile natal homing and population history likely play important roles. DT and EP were genetically similar to feeding grounds along the southern US coast, but highly differentiated from most other Atlantic groups. Despite expanded mitogenomic analysis and correspondingly increased ability to detect genetic variation, no significant differentiation between DT and EP, or among years, sexes or stages was observed. This first genetic analysis of a North Atlantic green turtle courtship area provides rare data supporting local movements and male philopatry. The study highlights the applications of multidisciplinary approaches for ecological research and conservation.

  20. Multilocus Phylogeny of the Afrotropical Freshwater Crab Fauna Reveals Historical Drainage Connectivity and Transoceanic Dispersal Since the Eocene.

    PubMed

    Daniels, Savel R; Phiri, Ethel E; Klaus, Sebastian; Albrecht, Christian; Cumberlidge, Neil

    2015-07-01

    Phylogenetic reconstruction, divergence time estimations and ancestral range estimation were undertaken for 66% of the Afrotropical freshwater crab fauna (Potamonautidae) based on four partial DNA loci (12S rRNA, 16S rRNA, cytochrome oxidase one [COI], and histone 3). The present study represents the most comprehensive taxonomic sampling of any freshwater crab family globally, and explores the impact of paleodrainage interconnectivity on cladogenesis among freshwater crabs. Phylogenetic analyses of the total evidence data using maximum-likelihood (ML), maximum parsimony (MP), and Bayesian inference (BI) produced a robust statistically well-supported tree topology that reaffirmed the monophyly of the Afrotropical freshwater crab fauna. The estimated divergence times suggest that the Afrotropical Potamonautidae diverged during the Eocene. Cladogenesis within and among several genera occurred predominantly during the Miocene, which was associated with major tectonic and climatic ameliorations throughout the region. Paleodrainage connectivity was observed with specimens from the Nilo-Sudan and East African coast proving to be sister to specimens from the Upper Guinea Forests in West Africa. In addition, we observed strong sister taxon affinity between specimens from East Africa and the Congo basin, including specimens from Lake Tanganyika, while the southern African fauna was retrieved as sister to the Angolan taxa. Within the East African clade we observed two independent transoceanic dispersal events, one to the Seychelles Archipelago and a second to Madagascar, while we observe a single transoceanic dispersal event from West Africa to São Tomé. The ancestral area estimation suggested a West African/East African ancestral range for the family with multiple dispersal events between southern Africa and East Africa, and between East Africa and Central Africa The taxonomic implications of our results are discussed in light of the widespread paraphyly evident among a

  1. Trophic connections in Lake Superior Part I: the offshore fish community

    USGS Publications Warehouse

    Gamble, A.E.; Hrabik, T.R.; Stockwell, J.D.; Yule, D.L.

    2011-01-01

    Detailed diet linkages within the offshore (> 80 m bathymetric depth) food web of Lake Superior are currently not well identified. We used analyses of fish stomach contents to create an empirically based food web model of the Lake Superior offshore fish community. Stomachs were collected seasonally (spring, summer, and fall) from nine offshore locations in 2005, using bottom and midwater trawls. In total, 2643 stomachs representing 12 fish species were examined. The predominant fish species collected were deepwater sculpin (Myoxocephalus thompsonii), siscowet (Salvelinus namaycush siscowet), kiyi (Coregonus kiyi), and cisco (Coregonus artedi). Mysis diluviana was the most common prey item, indicating that changes in Mysis abundance could have a profound impact on the entire offshore food web. Mysis was the primary diet item of deepwater sculpin (≥ 53% by mass) and kiyi (≥ 96% by mass) regardless of depth or season. The invasive Bythotrephes was an important diet component of the pelagic cisco in summer and fall. Deepwater sculpin were the primary diet item of siscowet (≥ 52% by mass), with coregonines appearing in the diet of larger (> 400 mm) siscowet. Non-metric multidimensional scaling analysis indicated that there were no statistically significant seasonal or site-specific differences in diets of deepwater sculpin, cisco, or kiyi. Site was the primary structuring factor in siscowet diets. Generally, in Lake Superior, the diet items of the dominant offshore species did not appear to be in danger from those types of major ecological shifts occurring in the lower Laurentian Great Lakes.

  2. Connectivity

    ERIC Educational Resources Information Center

    Grush, Mary, Ed.

    2006-01-01

    Connectivity has dramatically changed the landscape of higher education IT. From "on-demand" services for net-gen students and advanced eLearning systems for faculty, to high-performance computing grid resources for researchers, IT now provides more networked services than ever to connect campus constituents to each other and to the world.…

  3. Unusually limited pollen dispersal and connectivity of Pedunculate oak (Quercus robur) refugial populations at the species' southern range margin.

    PubMed

    Moracho, E; Moreno, G; Jordano, P; Hampe, A

    2016-07-01

    Low-latitudinal range margins of temperate and boreal plant species typically consist of scattered populations that persist locally in microrefugia. It remains poorly understood how their refugial habitats affect patterns of gene flow and connectivity, key components for their long-term viability and evolution. We examine landscape-scale patterns of historical and contemporary gene flow in refugial populations of the widespread European forest tree Pedunculate oak (Quercus robur) at the species' southwestern range margin. We sampled all adult trees (n = 135) growing in a 20 km long valley and genotyped 724 acorns from 72 mother trees at 17 microsatellite loci. The ten oak stands that we identified were highly differentiated and formed four distinct genetic clusters, despite sporadic historical dispersal being detectable. By far most contemporary pollination occurred within stands, either between local mates (85.6%) or through selfing (6.8%). Pollen exchange between stands (2.6%) was remarkably rare given their relative proximity and was complemented by long-distance pollen immigration (4.4%) and hybridization with the locally abundant Quercus pyrenaica (0.6%). The frequency of between-stand mating events decreased with increasing size and spatial isolation of stands. Overall, our results reveal outstandingly little long-distance gene flow for a wind-pollinated tree species. We argue that the distinct landscape characteristics of oaks' refugial habitats, with a combination of a rugged topography, dense vegetation and humid microclimate, are likely to increase plant survival but to hamper effective long-distance pollen dispersal. Moreover, local mating might be favoured by high tree compatibility resulting from genetic purging in these long-term relict populations. PMID:27146553

  4. Microwave-assisted extraction and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry for isolation and determination of polycyclic aromatic hydrocarbons in smoked fish.

    PubMed

    Ghasemzadeh-Mohammadi, Vahid; Mohammadi, Abdorreza; Hashemi, Maryam; Khaksar, Ramin; Haratian, Parivash

    2012-05-11

    A simple and efficient method was developed using microwave-assisted extraction (MAE) and dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) for the extraction and quantification of 16 polycyclic aromatic hydrocarbons (PAHs) in smoked fish. Benzo[a]pyrene, chrysene and pyrene were employed as model compounds and spiked to smoked fish to assess the extraction procedure. Several parameters, including the nature and volume of hydrolysis, extracting and disperser solvents, microwave time and pH, were optimized. In the optimum condition for MAE, 1g of fish sample was extracted in 12 mL KOH (2M) and ethanol with a 50:50 ratio in a closed-vessel system. For DLLME, 500 μL of acetone (disperser solvent) containing 100 μL of ethylene tetrachloride (extraction solvent) was rapidly injected by syringe into 12 mL of the sample extract solution (previously adjusted to pH 6.5), thereby forming a cloudy solution. Phase separation was performed by centrifugation and a volume of 1.5 μL of the sedimented phase was analyzed by GC-MS in select ion monitoring (SIM) mode. Satisfactory results were achieved when this method was applied to analyze the PAHs in smoked fish samples. The MAE-DLLME method coupled with GC-MS provided excellent enrichment factors (in the range of 244-373 for 16 PAHs) and good repeatability (with a relative standard deviation between 2.8 and 9%) for spiked smoked fish. The calibration graphs were linear in the range of 1-200 ng g(-1), with the square of the correlation coefficient (R(2))>0.981 and detection limits between 0.11 and 0.43 ng g(-1). The recoveries of those compounds in smoked fish were from 82.1% to 105.5%. A comparison of this method with previous methods demonstrated that the proposed method is an accurate, rapid and reliable sample-pretreatment method that gives very good enrichment factors and detection limits for extracting and determining PAHs from smoked fish. PMID:22483095

  5. Predicting connectivity of green turtles at Palmyra Atoll, central Pacific: a focus on mtDNA and dispersal modelling

    USGS Publications Warehouse

    Naro-Maciel, Eugenia; Gaughran, Stephen J.; Putman, Nathan F.; Amato, George; Arengo, Felicity; Dutton, Peter H.; McFadden, Katherine W.; Vintinner, Erin C.; Sterling, Eleanor J.

    2014-01-01

    Population connectivity and spatial distribution are fundamentally related to ecology, evolution and behaviour. Here, we combined powerful genetic analysis with simulations of particle dispersal in a high-resolution ocean circulation model to investigate the distribution of green turtles foraging at the remote Palmyra Atoll National Wildlife Refuge, central Pacific. We analysed mitochondrial sequences from turtles (n = 349) collected there over 5 years (2008–2012). Genetic analysis assigned natal origins almost exclusively (approx. 97%) to the West Central and South Central Pacific combined Regional Management Units. Further, our modelling results indicated that turtles could potentially drift from rookeries to Palmyra Atoll via surface currents along a near-Equatorial swathe traversing the Pacific. Comparing findings from genetics and modelling highlighted the complex impacts of ocean currents and behaviour on natal origins. Although the Palmyra feeding ground was highly differentiated genetically from others in the Indo-Pacific, there was no significant differentiation among years, sexes or stage-classes at the Refuge. Understanding the distribution of this foraging population advances knowledge of green turtles and contributes to effective conservation planning for this threatened species.

  6. Predicting connectivity of green turtles at Palmyra Atoll, central Pacific: a focus on mtDNA and dispersal modelling

    PubMed Central

    Naro-Maciel, Eugenia; Gaughran, Stephen J.; Putman, Nathan F.; Amato, George; Arengo, Felicity; Dutton, Peter H.; McFadden, Katherine W.; Vintinner, Erin C.; Sterling, Eleanor J.

    2014-01-01

    Population connectivity and spatial distribution are fundamentally related to ecology, evolution and behaviour. Here, we combined powerful genetic analysis with simulations of particle dispersal in a high-resolution ocean circulation model to investigate the distribution of green turtles foraging at the remote Palmyra Atoll National Wildlife Refuge, central Pacific. We analysed mitochondrial sequences from turtles (n = 349) collected there over 5 years (2008–2012). Genetic analysis assigned natal origins almost exclusively (approx. 97%) to the West Central and South Central Pacific combined Regional Management Units. Further, our modelling results indicated that turtles could potentially drift from rookeries to Palmyra Atoll via surface currents along a near-Equatorial swathe traversing the Pacific. Comparing findings from genetics and modelling highlighted the complex impacts of ocean currents and behaviour on natal origins. Although the Palmyra feeding ground was highly differentiated genetically from others in the Indo-Pacific, there was no significant differentiation among years, sexes or stage-classes at the Refuge. Understanding the distribution of this foraging population advances knowledge of green turtles and contributes to effective conservation planning for this threatened species. PMID:24451389

  7. Localization of kinesin superfamily proteins to the connecting cilium of fish photoreceptors.

    PubMed

    Beech, P L; Pagh-Roehl, K; Noda, Y; Hirokawa, N; Burnside, B; Rosenbaum, J L

    1996-04-01

    Kinesin superfamily proteins (KIFs) are probable motors in vesicular and non-vesicular transport along microtubular tracks. Since a variety of KIFs have been recently identified in the motile flagella of Chlamydomonas, we sought to ascertain whether KIFs are also associated with the connecting cilia of vertebrate rod photoreceptors. As the only structural link between the rod inner segment and the photosensitive rod outer segment, the connecting cilium is thought to be the channel through which all material passes into and out of the outer segment from the rod cell body. We have performed immunological tests on isolated sunfish rod inner-outer segments (RIS-ROS) using two antibodies that recognize the conserved motor domain of numerous KIFs (anti-LAGSE, a peptide antibody, and anti-Klp1 head, generated against the N terminus of Chlamydomonas Klp1) as well as an antibody specific to a neuronal KIF, KIF3A. On immunoblots of RIS-ROS, LAGSE antibody detected a prominent band at approximately 117 kDa, which is likely to be kinesin heavy chain, and Klp1 head antibody detected a single band at approximately 170 kDa; KIF3A antibody detected a polypeptide at approximately 85 kDa which co-migrated with mammalian KIF3A and displayed ATP-dependent release from rod cytoskeletons. Immunofluorescence localizations with anti-LAGSE and anti-Klp1 head antibodies detected epitopes in the axoneme and ellipsoid, and immunoelectron microscopy with the LAGSE antibody showed that the connecting cilium region was particularly antigenic. Immunofluorescence with anti-KIF3A showed prominent labelling of the connecting cilium and the area surrounding its basal body; the outer segment axoneme and parts of the inner segment coincident with microtubules were also labelled. We propose that these putative kinesin superfamily proteins may be involved in the translocation of material between the rod inner and outer segments. PMID:8718680

  8. Toward Discovery Support Systems: A Replication, Re-examination, and Extension of Swanson's Work on Literature-Based Discovery of a Connection between Raynaud's and Fish Oil.

    ERIC Educational Resources Information Center

    Gordon, Michael D.; Lindsay, Robert K.

    1996-01-01

    Describes the development of computer-based searching methods to support literature-based discoveries in medical literature through a replication of the discovery of a connection between Raynaud's disease and dietary fish oil. Topics include the logic of literature-based discovery, information retrieval methods for text analysis, and statistics…

  9. Crossing the impassable: genetic connections in 20 reef fishes across the eastern Pacific barrier

    PubMed Central

    Lessios, H.A; Robertson, D.R

    2006-01-01

    The ‘impassable’ Eastern Pacific Barrier (EPB), ca 5000 km of deep water separating the eastern from the central Pacific, is the World's widest marine biogeographic barrier. Sequencing of mitochondrial DNA in 20 reef fish morphospecies encountered on both sides of the barrier revealed cryptic speciation in two. Among the other 18 species only two showed significant differentiation (as revealed by haplotype networks and FST statistics) between the eastern and the central Pacific. Coalescence analyses indicated that genetic similarity in the 18 truly transpacific species resulted from different combinations of ages of most recent invasion and of levels of recurrent gene flow, with estimated times of initial separation ranging from approximately 30 000 to 1 Myr (ago). There is no suggestion of simultaneous interruptions of gene flow among the species. Migration across the EPB was previously thought to be exclusively eastward, but our evidence showed two invasions from east to west and eight cases in which subsequent gene flow possibly proceeded in the same direction. Thus, the EPB is sporadically permeable to propagules originating on either side. PMID:16901840

  10. Determination of endocrine disrupting compounds in fish liver, brain, and muscle using focused ultrasound solid-liquid extraction and dispersive solid phase extraction as clean-up strategy.

    PubMed

    Ros, Oihana; Vallejo, Asier; Olivares, Maitane; Etxebarria, Nestor; Prieto, Ailette

    2016-08-01

    This study describes a new method for the simultaneous extraction of several endocrine disrupting compounds, including alkylphenols (APs), estrogen, bisphenol-A (BPA) and one phthalate metabolite (mono-2-ethylhexyl ester, MEHP) in fish liver, brain, and muscle. Parameters affecting the extraction (extraction solvent and temperature) and the clean-up (dispersive phase nature and amount) steps were evaluated. The extraction was performed by means of focused ultrasound solid-liquid extraction (FUSLE) using 10 mL of n-hexane:acetone (50:50, v/v) for 5 min at ~0 °C, and the clean-up was done by means of dispersive solid phase extraction (dSPE) using 100 mg of ENVI-CARB and 100 mg of MgSO4 for the cleaning of brain and muscle extracts together with 100 mg of PSA in the case of liver extracts. Good apparent recoveries were obtained in the case of liver (62-132 %), brain (66-120 %), and muscle (74-129 %), relative standard deviation (RSD%) was always below 26 %, and the method detection limits (MDLs) were at low ng/g level. The developed method was applied to fish captured in Urdaibai estuary (Bay of Biscay) in December 2015, and the concentrations obtained were in the range MDL-1115 ng/g in brain, MDL-962 ng/g in muscle, and MDL-672 ng/g in liver. In general, the highest concentrations were measured in liver, followed by brain and muscle. In addition, diethylstilbestrol was only detected in fish brain. Graphical Abstract MS method scheme for the/MS method scheme for the determination of EDCs in fish liver, brain and muscle. PMID:27342793

  11. Genes meet geology: fish phylogeographic pattern reflects ancient, rather than modern, drainage connections.

    PubMed

    Waters, J M; Craw, D; Youngson, J H; Wallis, G P

    2001-09-01

    We used DNA analysis of the freshwater Galaxias vulgaris complex (Pisces: Galaxiidae) to test a geological hypothesis of drainage evolution in South Island, New Zealand. Geological evidence suggests that the presently north-flowing Nevis River branch of the Clutha/Kawarau River system (Otago) once flowed south into the Nokomai branch of the Mataura system (Southland). The flow reversal is thought to have resulted from fault and fold activity associated with post-Miocene uplift. Mitochondrial DNA sequence data (control region and cytochrome b genes; 76 individuals; maximum divergence 7.1%) corroborate this geomorphological hypothesis: The Nevis River retains a freshwater fish species (Galaxias gollumoides; five sites; 10 haplotypes) that is otherwise restricted to Southland (nine sites; 15 haplotypes). There is no indication that the Nevis River lineage of G. gollumoides lives elsewhere in the Clutha/ Kawarau system (> 30 sites). Likewise, two widespread Clutha lineages (G. 'sp D'; G. anomalus-G. pullus) are apparently absent from the Nevis (> 30 sites). In particular, G. 'sp D' lives throughout much of the Clutha (12 sites, 23 haplotypes), including a tributary of the Kawarau, but is absent from the Nevis itself. Conventional molecular clock calibrations (based on a minimum Nevis-Mataura haplotype divergence of 3.0%) indicate that the Nevis flow reversal may have occurred in the early-mid Pleistocene, which is roughly consistent with geological data. The broad phylogeographic structure evident in the Clutha system is consistent with the sedentary nature of nonmigratory galaxiids. Our study reinforces the value of combining biological and geological data for the formulation and testing of historical hypotheses. PMID:11681739

  12. Persistence and extirpation in invaded landscapes: patch characteristics and connectivity determine effects of non-native predatory fish on native salamanders

    USGS Publications Warehouse

    Pilliod, David S.; Arkle, Robert S.; Maxell, Bryce A.

    2012-01-01

    Studies have demonstrated negative effects of non-native, predatory fishes on native amphibians, yet it is still unclear why some amphibian populations persist, while others are extirpated, following fish invasion. We examined this question by developing habitat-based occupancy models for the long-toed salamander (Ambystoma macrodactylum) and nonnative fish using survey data from 1,749 water bodies across 470 catchments in the Northern Rocky Mountains, USA. We first modeled the habitat associations of salamanders at 468 fishless water bodies in 154 catchments where non-native fish were historically, and are currently, absent from the entire catchment. Wethen applied this habitat model to the complete data set to predict the probability of salamander occupancy in each water body, removing any effect of fish presence. Finally, we compared field-observed occurrences of salamanders and fish to modeled probability of salamander occupancy. Suitability models indicated that fish and salamanders had similar habitat preferences, possibly resulting in extirpations of salamander populations from entire catchments where suitable habitats were limiting. Salamanders coexisted with non-native fish in some catchments by using marginal quality, isolated (no inlet or outlet) habitats that remained fishless. They rarely coexisted with fish within individual water bodies and only where habitat quality was highest. Connectivity of water bodies via streams resulted in increased probability of fish invasion and consequently reduced probability of salamander occupancy.These results could be used to identify and prioritize catchments and water bodies where control measures would be most effective at restoring amphibian populations. Our approach could be useful as a framework for improved investigations into questions of persistence and extirpation of native species when non-native species have already become established.

  13. Catecholaminergic connectivity to the inner ear, central auditory and vocal motor circuitry in the plainfin midshipman fish, Porichthys notatus

    PubMed Central

    Forlano, Paul M.; Kim, Spencer D.; Krzyminska, Zuzanna M.; Sisneros, Joseph A.

    2014-01-01

    Although the neuroanatomical distribution of catecholaminergic (CA) neurons has been well documented across all vertebrate classes, few studies have examined CA connectivity to physiologically and anatomically identified neural circuitry that controls behavior. The goal of this study was to characterize CA distribution in the brain and inner ear of the plainfin midshipman fish (Porichthys notatus) with particular emphasis on their relationship with anatomically labeled circuitry that both produces and encodes social acoustic signals in this species. Neurobiotin labeling of the main auditory endorgan, the saccule, combined with tyrosine hydroxylase immunofluorescence (TH-ir) revealed a strong CA innervation of both the peripheral and central auditory system. Diencephalic TH-ir neurons in the periventricular posterior tuberculum, known to be dopaminergic, send ascending projections to the ventral telencephalon and prominent descending projections to vocal-acoustic integration sites, notably the hindbrain octavolateralis efferent nucleus, as well as onto the base of hair cells in the saccule via nerve VIII. Neurobiotin backfills of the vocal nerve in combination with TH-ir revealed CA terminals on all components of the vocal pattern generator which appears to largely originate from local TH-ir neurons but may include diencephalic projections as well. This study provides strong evidence for catecholamines as important neuromodulators of both auditory and vocal circuitry and acoustic-driven social behavior in midshipman fish. This first demonstration of TH-ir terminals in the main endorgan of hearing in a non-mammalian vertebrate suggests a conserved and important anatomical and functional role for dopamine in normal audition. PMID:24715479

  14. Element distribution over the surface of fish scales and its connection to the geochemical environment of habitats: a potential biogeochemical tag.

    PubMed

    Wang, TsingHai; Lai, Yan-Chen; Chiang, Chia-Che; Cheng, Yu-Rong; Hsieh, Yi-Kong; Wang, Chu-Fang

    2016-03-01

    The elemental content of fish scales is known to be a reliable biogeochemical tag for tracing the origin of fishes. In this study, this correlation is further confirmed to exist on the surface of fish scales using a novel environmental analytical method, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), which bypasses several complicated sample preparation procedures such as acid digestion and pre-concentration. The results suggest that the elemental ratios of Sr/Ca, Ba/Ca, and Mn/Ca on the surface of fish scales are strongly correlated with the geochemical environment of their original habitat. This correlation is further demonstrated to be sensitive to variation of water in the habitat due to the adsorbed inorganic ions. In this sense, the limitation of fish scales as a biogeochemical tag is the sensitivity of LA-ICP-MS toward the studied elements. Graphical abstract Illustration of the connection between element distribution pattern over the surface of fish scales and biogeochemical environment of its habitat. PMID:26899028

  15. Genetic Connectivity among and Self-Replenishment within Island Populations of a Restricted Range Subtropical Reef Fish

    PubMed Central

    van der Meer, Martin H.; Hobbs, Jean-Paul A.; Jones, Geoffrey P.; van Herwerden, Lynne

    2012-01-01

    Marine protected areas (MPAs) are increasingly being advocated and implemented to protect biodiversity on coral reefs. Networks of appropriately sized and spaced reserves can capture a high proportion of species diversity, with gene flow among reserves presumed to promote long term resilience of populations to spatially variable threats. However, numerically rare small range species distributed among isolated locations appear to be at particular risk of extinction and the likely benefits of MPA networks are uncertain. Here we use mitochondrial and microsatellite data to infer evolutionary and contemporary gene flow among isolated locations as well as levels of self-replenishment within locations of the endemic anemonefish Amphiprion mccullochi, restricted to three MPA offshore reefs in subtropical East Australia. We infer high levels of gene flow and genetic diversity among locations over evolutionary time, but limited contemporary gene flow amongst locations and high levels of self-replenishment (68 to 84%) within locations over contemporary time. While long distance dispersal explained the species’ integrity in the past, high levels of self-replenishment suggest locations are predominantly maintained by local replenishment. Should local extinction occur, contemporary rescue effects through large scale connectivity are unlikely. For isolated islands with large numbers of endemic species, and high local replenishment, there is a high premium on local species-specific management actions. PMID:23185398

  16. Genetic connectivity among and self-replenishment within island populations of a restricted range subtropical reef fish.

    PubMed

    van der Meer, Martin H; Hobbs, Jean-Paul A; Jones, Geoffrey P; van Herwerden, Lynne

    2012-01-01

    Marine protected areas (MPAs) are increasingly being advocated and implemented to protect biodiversity on coral reefs. Networks of appropriately sized and spaced reserves can capture a high proportion of species diversity, with gene flow among reserves presumed to promote long term resilience of populations to spatially variable threats. However, numerically rare small range species distributed among isolated locations appear to be at particular risk of extinction and the likely benefits of MPA networks are uncertain. Here we use mitochondrial and microsatellite data to infer evolutionary and contemporary gene flow among isolated locations as well as levels of self-replenishment within locations of the endemic anemonefish Amphiprion mccullochi, restricted to three MPA offshore reefs in subtropical East Australia. We infer high levels of gene flow and genetic diversity among locations over evolutionary time, but limited contemporary gene flow amongst locations and high levels of self-replenishment (68 to 84%) within locations over contemporary time. While long distance dispersal explained the species' integrity in the past, high levels of self-replenishment suggest locations are predominantly maintained by local replenishment. Should local extinction occur, contemporary rescue effects through large scale connectivity are unlikely. For isolated islands with large numbers of endemic species, and high local replenishment, there is a high premium on local species-specific management actions. PMID:23185398

  17. Estimating contemporary early life-history dispersal in an estuarine fish: integrating molecular and otolith elemental approaches.

    PubMed

    Bradbury, I R; Campana, S E; Bentzen, P

    2008-03-01

    Dispersal during the early life history of the anadromous rainbow smelt, Osmerus mordax, was examined using assignment testing and mixture analysis of multilocus genotypes and otolith elemental composition. Six spawning areas and associated estuarine nurseries were sampled throughout southeastern Newfoundland. Samples of adults and juveniles isolated by > 25 km displayed moderate genetic differentiation (F(ST) ~ 0.05), whereas nearby (< 25 km) spawning and nursery samples displayed low differentiation (F(ST) < 0.01). Self-assignment and mixture analysis of adult spawning samples supported the hypothesis of independence of isolated spawning locations (> 80% self-assignment) with nearby runs self-assigning at rates between 50 % and 70%. Assignment and mixture analysis of juveniles using adult baselines indicated high local recruitment at several locations (70-90%). Nearby (< 25 km) estuaries at the head of St Mary's Bay showed mixtures of individuals (i.e. 20-40% assignment to adjacent spawning location). Laser ablation inductively coupled mass spectrometry transects across otoliths of spawning adults of unknown dispersal history were used to estimate dispersal among estuaries across the first year of life. Single-element trends and multivariate discriminant function analysis (Sr:Ca and Ba:Ca) classified the majority of samples as estuarine suggesting limited movement between estuaries (< 0.5%). The mixtures of juveniles evident in the genetic data at nearby sites and a lack of evidence of straying in the otolith data support a hypothesis of selective mortality of immigrants. If indeed selective mortality of immigrants reduces the survivorship of dispersers, estimates of dispersal in marine environments that neglect survival may significantly overestimate gene flow. PMID:18321254

  18. Population connectivity and the effectiveness of marine protected areas to protect vulnerable, exploited and endemic coral reef fishes at an endemic hotspot

    NASA Astrophysics Data System (ADS)

    van der Meer, M. H.; Berumen, M. L.; Hobbs, J.-P. A.; van Herwerden, L.

    2015-06-01

    Marine protected areas (MPAs) aim to mitigate anthropogenic impacts by conserving biodiversity and preventing overfishing. The effectiveness of MPAs depends on population connectivity patterns between protected and non-protected areas. Remote islands are endemism hotspots for coral reef fishes and provide rare examples of coral reefs with limited fishing pressure. This study explored population genetic connectivity across a network of protected and non-protected areas for the endemic wrasse, Coris bulbifrons, which is listed as "vulnerable" by the IUCN due to its small, decreasing geographic range and declining abundance. Mitochondrial DNA (mtDNA) and microsatellite DNA (msatDNA) markers were used to estimate historic and contemporary gene flow to determine the level of population self-replenishment and to measure genetic and genotypic diversity among all four locations in the species range (south-west Pacific Ocean)—Middleton Reef (MR), Elizabeth Reef (ER), Lord Howe Island (LHI) and Norfolk Island (NI). MPAs exist at MR and LHI and are limited or non-existent at ER and NI, respectively. There was no obvious differentiation in mtDNA among locations, however, msatDNA revealed differentiation between the most peripheral (NI) and all remaining locations (MR, ER and LHI). Despite high mtDNA connectivity ( M = 259-1,144), msatDNA connectivity was limited ( M = 3-9) with high self-replenishment (68-93 %) at all locations. NI is the least connected and heavily reliant on self-replenishment, and the absence of MPAs at NI needs to be rectified to ensure the persistence of endemic species at this location. Other endemic fishes exhibit similar patterns of high self-replenishment across the four locations, indicating that a single spatial management approach consisting of a MPA network protecting part of each location could provide reasonable protection for these species. Thus, the existing network of MPAs at this endemic hotspot appears adequate at some locations, but not

  19. First-year dam removal activities in the Elwha River - dam removal, sediment dispersal, and fish relocations

    NASA Astrophysics Data System (ADS)

    Duda, J. J.; McMillan, J. R.; Moses, R.; McHenry, M.; Pess, G. R.; Brenkman, S.; Peters, R.; Zimmerman, M.; Warrick, J. A.; Curran, C. A.; Magirl, C. S.; Beirne, M.; Rubin, S.

    2012-12-01

    After years of anticipation, volumes of Environmental Impact Statements, unprecedented mitigation projects, and the multifaceted collection of pre-dam removal data, the deconstruction phase of the Elwha River restoration project officially began on September 17th, 2011. With their simultaneous decommissioning, the removal of the 64 m tall Glines Canyon Dam and 33 m tall Elwha Dam represents one of the largest such projects of its kind in North America. The nearly 19 million m3 of sediment residing in the dammed reservoirs is being eroded by the river in one of the largest controlled releases of sediment into a river and marine waters in recorded history. The release of sediment and the halting of deconstruction and reservoir draw down activities during "fish windows" are largely determining a deconstruction schedule expected to last about 2 years. High suspended sediment concentrations, modeled to exceed 10,000 mg/L during the highest flows and to exceed 500 mg/L for 39% of the time in year 4 of the project (15% is the recorded background level entering the upper reservoir), could last for up to 3-5 years following dam removal depending on hydrological conditions. Anadromous fish, including three federally listed species (Puget Sound Chinook salmon, steelhead, and bull trout), reside in the river downstream of the Elwha dam for part of their life cycle. All five species of Pacific salmon and steelhead, either locally extirpated (sockeye) or persisting below the impassable Elwha Dam in degraded spawning and rearing habitat, are expected to recolonize the watershed to degrees that will vary spatially and temporally due to life history characteristics and levels of human intervention. During the first year of dam removal, adult coho salmon and steelhead were relocated from areas of high turbidity downstream of the Elwha Dam site to two tributaries upstream, where some of them successfully spawned. Additionally, steelhead were observed to naturally migrate past the

  20. Assessment of modified matrix solid-phase dispersion as sample preparation for the determination of CH3Hg+ and Hg2+ in fish.

    PubMed

    Duarte, Fabio A; Soares, Bruno M; Vieira, Augusto A; Pereira, Ederson R; Maciel, Juliana V; Caldas, Sergiane S; Primel, Ednei G

    2013-05-21

    This paper reports, for the first time, the development of an analytical method employing modified matrix solid-phase dispersion (MSPD) for the extraction of CH3Hg(+) and Hg(2+) species from fish samples. Separation and determination of mercury species were performed by gas chromatography coupled to mass spectrometry (GC/MS). Important MSPD parameters, such as sample mass, type and mass of solid support, concentration of extraction solution (HCl and NaCl), and stirring time, were investigated by the response surface methodology. The derivatization step and the separation of mercury species were also evaluated for the determination by GC/MS. Quantitative recoveries were obtained with 0.2 g of fish sample, 0.5 g of SiO2 as the solid support, 0.5 mol L(-1) NaCl and 4.2 mol L(-1) HCl as the extraction solution, and 1 min stirring time. The MSPD method showed to be suitable for the extraction and determination of mercury species in certified reference materials of dogfish liver (DOLT-3) and dogfish muscle (DORM-2). It had good agreement (about 99%) with the certified values, and the relative standard deviation was lower than 9.5%. The limits of detection were 0.06 and 0.12 μg g(-1), for CH3Hg(+) and Hg(2+), respectively. A matrix effect was observed, and the quantification was carried out by the matrix-matched calibration. The method was applied to tuna fish ( Thunnus thynnus ), angel shark ( Squatina squatina ), and guitarfish ( Rhinobatos percellens ) samples. The results of the mercury speciation by MPSD and GC/MS were compared to the total mercury concentration determined by flow injection cold vapor generation inductively coupled plasma mass spectrometry, after microwave-assisted digestion. Agreement ranged from 102% to 105%. PMID:23614538

  1. Back to Tanganyika: a case of recent trans-species-flock dispersal in East African haplochromine cichlid fishes.

    PubMed

    Meyer, Britta S; Indermaur, Adrian; Ehrensperger, Xenia; Egger, Bernd; Banyankimbona, Gaspard; Snoeks, Jos; Salzburger, Walter

    2015-03-01

    The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here, we report the discovery of a haplochromine cichlid species in Lake Tanganyika, which belongs genetically to the species flock of haplochromines of the Lake Victoria region. The new species colonized Lake Tanganyika only recently, suggesting that faunal exchange across watersheds and, hence, between isolated ichthyofaunas, is more common than previously thought. PMID:26064619

  2. Back to Tanganyika: a case of recent trans-species-flock dispersal in East African haplochromine cichlid fishes

    PubMed Central

    Meyer, Britta S.; Indermaur, Adrian; Ehrensperger, Xenia; Egger, Bernd; Banyankimbona, Gaspard; Snoeks, Jos; Salzburger, Walter

    2015-01-01

    The species flocks of cichlid fishes in the East African Great Lakes are the largest vertebrate adaptive radiations in the world and illustrious textbook examples of convergent evolution between independent species assemblages. Although recent studies suggest some degrees of genetic exchange between riverine taxa and the lake faunas, not a single cichlid species is known from Lakes Tanganyika, Malawi and Victoria that is derived from the radiation associated with another of these lakes. Here, we report the discovery of a haplochromine cichlid species in Lake Tanganyika, which belongs genetically to the species flock of haplochromines of the Lake Victoria region. The new species colonized Lake Tanganyika only recently, suggesting that faunal exchange across watersheds and, hence, between isolated ichthyofaunas, is more common than previously thought. PMID:26064619

  3. Low Rate of Between-Population Seed Dispersal Restricts Genetic Connectivity and Metapopulation Dynamics in a Clonal Shrub

    PubMed Central

    Merwin, Laura; He, Tianhua; Lamont, Byron B.; Enright, Neal J.; Krauss, Siegfried L.

    2012-01-01

    Clonal species normally have low seed production, low recruitment rates and long lifespans, and it is expected that the rates of long-distance dispersal (LDD) of seeds will be low as well. Banksia candolleana is a clonal shrub in Mediterranean-type, fire-prone sclerophyll shrublands of southwestern Australia, whose reproductive biology and population dynamics contrast with those of co-occurring nonclonal congeneric species, all of which are restricted to a mosaic of sand dunes set within a matrix of inhospitable swales. Using microsatellite markers, we genotyped 499 plants in all 15 populations of B. candolleana within a 12-km2 area, assessed population genetic differentiation, and quantified the effective rate of interpopulation seed dispersal through genetic assignment of individuals to populations. We measured life history, reproductive and demographic attributes, and compared these with two co-occurring Banksia species, a non-clonal resprouter and a nonsprouter. B. candolleana has much higher levels of population genetic differentiation, and one-third the rate of interpopulation seed migration, as the other two species (2.2% vs 5.5−6.8% of genotyped plants inferred to be immigrants), though distances reached by LDD are comparable (0.3−2.3 km). The low rate of interpopulation dispersal was supported by an analysis of the age structure of three populations that suggests a mean interdune migration rate of <800 m in 200 years, and 60% of suitable dunes remain uninhabited. Thus, B. candolleana has poor properties for promoting long-distance dispersal. It is unclear if these are idiosyncratic to this species or whether such properties are to be expected of clonal species in general where LDD is less critical for species survival. PMID:23209839

  4. Contrasting levels of connectivity and localised persistence characterise the latitudinal distribution of a wind-dispersed rainforest canopy tree.

    PubMed

    Heslewood, Margaret M; Lowe, Andrew J; Crayn, Darren M; Rossetto, Maurizio

    2014-06-01

    Contrasting signals of genetic divergence due to historic and contemporary gene flow were inferred for Coachwood, Ceratopetalum apetalum (Cunoniaceae), a wind-dispersed canopy tree endemic to eastern Australian warm temperate rainforest. Analysis of nine nuclear microsatellites across 22 localities revealed two clusters between northern and southern regions and with vicariance centred on the wide Hunter River Valley. Within populations diversity was high indicating a relatively high level of pollen dispersal among populations. Genetic variation was correlated to differences in regional biogeography and ecology corresponding to IBRA regions, primary factors being soil type and rainfall. Eleven haplotypes were identified by chloroplast microsatellite analysis from the same 22 localities. A lack of chloroplast diversity within sites demonstrates limited gene flow via seed dispersal. Network representation indicated regional sharing of haplotypes indicative of multiple Pleistocene refugia as well as deep divergences between regional elements of present populations. Chloroplast differentiation between sites in the upper and lower sections of the northern population is reflective of historic vicariance at the Clarence River Corridor. There was no simple vicariance explanation for the distribution of the divergent southern chlorotype, but its distribution may be explained by the effects of drift from a larger initial gene pool. Both the Hunter and Clarence River Valleys represent significant dry breaks within the species range, consistent with this species being rainfall dependent rather than cold-adapted. PMID:24898671

  5. Delimiting Evolutionarily Significant Units of the Fish, Piaractus brachypomus (Characiformes: Serrasalmidae), from the Orinoco and Amazon River Basins with Insight on Routes of Historical Connectivity.

    PubMed

    Escobar, Maria Doris; Andrade-López, Juana; Farias, Izeni P; Hrbek, Tomas

    2015-01-01

    The freshwater fish Piaractus brachypomus is an economically important for human consumption both in commercial fisheries and aquaculture in all South American countries where it occurs. In recent years the species has decreased in abundance due to heavy fishing pressure. The species occurs in the Amazon and Orinoco basins, but lack of meristic differences between fishes from the 2 basins, and extensive migration associated with reproduction, have resulted in P. brachypomus being considered a single panmictic species. Analysis of 7 nuclear microsatellites, mitochondrial DNA sequences (D-loop and COI), and body shape variables demonstrated that each river basin is populated by a distinct evolutionarily significant unit (ESU); the 2 groups had an average COI divergence of 3.5% and differed in body depth and relative head length. Historical connection between the 2 basins most probably occurred via the Rupununi portal rather than via the Casiquiare canal. The 2 ESUs will require independent fishery management, and translocation of fisheries stocks between basins should be avoided to prevent loss of local adaptations or extinction associated with outbreeding depression. Introductions of fishes from the Orinoco basin into the Putumayo River basin, an Amazon basin drainage, and evidence of hybridization between the 2 ESUs have already been detected. PMID:26245778

  6. Reservoir to river passage of age-0+ year fishes, indication of a dispersion pathway for a non-native species.

    PubMed

    Janáč, M; Jurajda, P; Kružíková, L; Roche, K; Prášek, V

    2013-03-01

    This study demonstrates passage of age-0+ year individuals of pikeperch Sander lucioperca, common bream Abramis brama and non-native tubenose goby Proterorhinus semilunaris from the Nové Mlýny Reservoir into the River Dyje (Danube River basin, Czech Republic) through the turbine of a hydropower facility. Most fishes had standard length (LS ) in the range 12-33 mm. Seasonal patterns corresponded with spawning activity, i.e. an early single spawning event for S. lucioperca, multiple spawning events for A. brama and continuous spawning with a later start and prolonged duration for P. semilunaris. Sander lucioperca, P. semilunaris and larger A. brama (>22 mm) drifted almost exclusively during the dark; smaller A. brama displayed no preference for light or dark. Proterorhinus semilunaris displayed significantly lower mortality than other species when passing through the turbine (3% compared to 18%). The passage of high numbers of P. semilunaris from the reservoir (estimated at 473 000 individuals per year), and their subsequent mass downstream drift, may have contributed to rapid population establishment along the River Dyje and the quick downstream expansion. PMID:23464556

  7. Constraints to connecting children with nature--Survey of U.S. Fish and Wildlife Service employees sponsored by the National Conservation Training Center, Division of Education Outreach

    USGS Publications Warehouse

    Ratz, Joan M.; Schuster, Rudy M.

    2011-01-01

    The U.S. Fish and Wildlife Service (FWS) names "connecting people with nature" as one of its top six priorities in the online Service Employee Pocket Guide. The National Conservation Training Center (NCTC) took the initiative to identify issues that impede greater progress in addressing constraints to connecting children with nature. The Division of Education Outreach at NCTC formed a working relation with the Policy Analysis and Science Assistance branch of the U.S. Geological Survey to conduct a study on these issues. To meet the objectives of the study, a survey of a sample of FWS employees was conducted. This report includes the description of how the survey was developed and administered, how the data were analyzed, and a discussion of the survey results. The survey was developed based on published literature and incorporated input from two working groups of professionals focused on the issue of connecting children with nature. Although the objective as stated by the FWS is to connect people with nature, the survey primarily focused on connecting children, rather than all people, with nature. The four primary concepts included on the survey were interpretation of how the FWS defined "connection" as part of its mission, perceived success with outreach, constraints to connecting children with nature, and importance of connecting children with nature. The survey was conducted online using KeySurvey© software. The survey was sent to 604 FWS employees. Responses were received from 320 employees. The respondents represented diversity in regions, tenure, wage/grade level, job series, supervisory status, and involvement with education and outreach activities. The key findings of the survey are as follows: * FWS employees believe they as individuals and the agency are successful now and will be more successful in the future in connecting children with nature. * FWS employees believe that there are many outcomes that are relevant to the FWS objective to connect people

  8. A survey of U.S. Fish and Wildlife Service employees regarding constraints to connecting children with nature-Summary report to respondents

    USGS Publications Warehouse

    Ratz, Joan M.; Schuster, Rudy M.

    2011-01-01

    This report provides a summary of responses to the questions included on a survey of U.S. Fish and Wildlife Service employees regarding constraints to connecting children with nature. The survey was sponsored by the Division of Education Outreach at the National Conservation Training Center and conducted by the U.S. Geological Survey. The data collection process started on February 25, 2010 and ended on March 9, 2010. The dataset includes the responses from 320 individuals from all regions in the Service. The adjusted response rate for the survey was 55 percent. In this report, we provide the summary results for the survey questions in the order in which the questions were asked. The questions addressed the following topics: relevance of certain outcomes to the aspect of the Service's mission that relates to connecting people with nature, perceived success at connecting children with nature, the extent to which ten constraints present problems in connecting children with nature, and attitudes about the importance of connecting children with nature. The text of comments provided by respondents to open-ended questions is provided. In-depth analyses will be reported in the completion report for this project.

  9. Genetic signatures of historical dispersal of fish threatened by biological invasions: the case of galaxiids in South America

    USGS Publications Warehouse

    Vanhaecke, Delphine; Garcia de Leaniz, Carlos; Gajardo, Gonzalo; Dunham, Jason; Giannico, Guillermo; Consegura, Sofia

    2015-01-01

    Aim The ecological effects of biological invasions are well documented, but little is known about the effects of invaders on the genetic structure of native species. We examined the phylogeography, genetic variation and population structuring of two galaxiid fishes, Aplochiton zebraand A. taeniatus, threatened by non-native salmonids, and whose conservation is complicated by misidentification and limited knowledge of their genetic diversity. Location Chile and the Falkland Islands. Methods We combined microsatellite and mitochondrial DNA (16S rDNA and COI) markers to compare genetic diversity, effective population size and gene flow of Aplochiton spp. populations differentially affected by salmonid presence. Results We identified two 16S rDNA haplotypes among A. zebra – one dominant in coastal populations and another dominant in inland populations. Populations living on the island of Chiloé displayed a mixture of coastal and inland haplotypes, as well as high microsatellite diversity, as one would expect if the island had been a refugium during the Last Glacial Maximum, or a contact zone among populations. Microsatellite data revealed strong population structuring, indicative of current isolation patterns, and a negative correlation between the genetic diversity of A. zebra and the relative abundance of invasive salmonids. Main conclusions Our study indicates that population structuring of A. zebra reflects the influence of historical patterns of migration, but also the current levels of reduced gene flow among watersheds. Invasive salmonids, known to compete with and prey on native galaxiids, may have had negative impacts on the genetic diversity of Aplochiton spp. The low genetic variation found in some populations, coupled with potential biases in abundance estimates due to species misidentification, highlight the urgent need for more research into the conservation status of the two species of Aplochiton.

  10. Analysis of trace levels of sulfonamides in fish tissue using micro-scale pipette tip-matrix solid-phase dispersion and fast liquid chromatography tandem mass spectrometry.

    PubMed

    Shen, Qing; Jin, Renyao; Xue, Jing; Lu, Yanbin; Dai, Zhiyuan

    2016-03-01

    A micro-scale matrix solid-phase dispersion (MSPD) technique, using hydrophilic-lipophilic balance (HLB) material as sorbent and a pipette tip (PT) as the cartridge, was developed for the extraction and purification of sulfonamides in fish tissue. Eluates from PT-MSPD were analyzed using fast liquid chromatography and tandem mass spectrometry (LC-MS/MS). The method was fully validated; good linearity was obtained with correlation coefficients greater than 0.99. Precision and accuracy (RSD%) were in the range 1.4-10.3% while mean recoveries were 70.6-95.5%. With this technique, 15 aquatic samples (Collichthys niveatus) were analyzed for sulfonamides. The whole procedure took only 13min (5min for PT-MSPD and 8min for LC), materials for each sample included 5.1mL solvents (0.3mL for PT-MSPD and 4.8mL for LC), and 20mg HLB sorbent. Generally speaking, this method is indeed practical and particularly suitable for widespread drug residue analysis. PMID:26471586

  11. The importance of chain connectivity in the formation of non-covalent interactions between polymers and single-walled carbon nanotubes and its impact on dispersion

    SciTech Connect

    Linton, Dias; Driva, Paraskevi; Ivanov, Ilia N; Geohegan, David B; Feigerle, Charles S; Dadmun, Mark D

    2010-05-01

    In this study we investigate the formation of non-covalent electron donor acceptor (EDA) interactions between polymers and single-walled carbon nanotubes (SWNTs) with the goal of optimizing interfacial adhesion and homogeneity of nanocomposites without modifying the SWNT native surface. Nanocomposites of SWNTs and three sets of polymer matrices with varying composition of electron donating 2-(dimethylamino)ethyl methacrylate (DMAEMA) or electron accepting acrylonitrile (AN) and cyanostyrene (CNSt) were prepared, quantitatively characterized by optical microscopy and Raman spectroscopy (Raman mapping, Raman D* peak shifts) and qualitatively compared through thick film composite visualization. The experimental data show that copolymers with 30 mol% DMAEMA, 45 mol% AN, 23 mol% CNSt and polyacrylonitrile homopolymer have the highest extent of intermolecular interaction, which translates to an optimum SWNT spatial dispersion among the series. These results are found to correlate very well with the intermolecular interaction energies obtained from quantum density functional theory calculations. Both experimental and computational results also illustrate that chain connectivity is critical in controlling the accessibility of the functional groups to form intermolecular interactions. This means that an adequate distance between interacting functional groups on a polymer chain is needed in order to allow efficient intermolecular contact. Thus, controlling the amount of electron donating or withdrawing moieties throughout the polymer chain will direct the extent of EDA interaction, which enables tuning the SWNT dispersion.

  12. The importance of chain connectivity in the formation of non-covalent interactions between polymers and single-walled carbon nanotubes and its impact on dispersion

    SciTech Connect

    Sumpter, Bobby G; Dadmun, Mark D; Driva, Paraskevi; Ivanov, Ilia N; Geohegan, David B; Linton, Dias; Feigerle, Charles S

    2010-01-01

    In this study we investigate the formation of non-covalent electron donor acceptor (EDA) interactions between polymers and single-walled carbon nanotubes (SWNTs) with the goal of optimizing interfacial adhesion and homogeneity of nanocomposites without modifying the SWNT native surface. Nanocomposites of SWNTs and three sets of polymer matrices with varying composition of electron donating 2-(dimethylamino)ethyl methacrylate (DMAEMA) or electron accepting acrylonitrile (AN) and cyanostyrene (CNSt) were prepared, quantitatively characterized by optical microscopy and Raman spectroscopy (Raman mapping, Raman D* peak shifts) and qualitatively compared through thick film composite visualization. The experimental data show that copolymers with 30 mol% DMAEMA, 45 mol% AN, 23 mol% CNSt and polyacrylonitrile homopolymer have the highest extent of intermolecular interaction, which translates to an optimum SWNT spatial dispersion among the series. These results are found to correlate very well with the intermolecular interaction energies obtained from quantum density functional theory calculations. Both experimental and computational results also illustrate that chain connectivity is critical in controlling the accessibility of the functional groups to form intermolecular interactions. This means that an adequate distance between interacting functional groups on a polymer chain is needed in order to allow efficient intermolecular contact. Thus, controlling the amount of electron donating or withdrawing moieties throughout the polymer chain will direct the extent of EDA interaction, which enables tuning the SWNT dispersion.

  13. Long-distance dispersal, low connectivity and molecular evidence of a new cryptic species in the obligate rafter Caprella andreae Mayer, 1890 (Crustacea: Amphipoda: Caprellidae)

    NASA Astrophysics Data System (ADS)

    Cabezas, M. Pilar; Navarro-Barranco, Carlos; Ros, Macarena; Guerra-García, José Manuel

    2013-09-01

    The amphipod Caprella andreae Mayer, 1890 was recorded for the first time in Southern Iberian Peninsula (36°44'15″N, 3°59'38″W). This species is the only obligate rafter of the suborder Caprellidea and has been reported to attach not only to floating objects such as ropes or driftwoods but also to turtle carapaces. Mitochondrial and nuclear markers were used to examine dispersal capabilities and population genetic structure of C. andreae across seven localities in the Mediterranean and Atlantic Ocean collected from floating substrata with different dispersal patterns. The strong population differentiation with no haplotypes shared between populations suggests that C. andreae is quite faithful to the substratum on which it settles. In addition, the proportionally higher genetic diversity displayed in populations living on turtles as well as the presence of highly differentiated haplotypes in the same turtle population may be indicative that these populations survive longer, which could lead C. andreae to prefer turtles instead of floating objects to settle and disperse. Therefore, rafting on floating objects may be sporadic, and ocean currents would not be the most important factor shaping patterns of connectivity and population structure in this species. Furthermore, molecular phylogenetic analyses revealed the existence of a cryptic species whose estimates of genetic divergence are higher than those estimated between C. andreae and other congeneric species (e.g. Caprella dilatata and Caprella penantis). Discovery of cryptic species among widely distributed small marine invertebrates is quite common and, in this case, prompts for a more detailed phylogenetic analysis and taxonomic revision of genus Caprella. On the other hand, this study also means the first record of the gammarids Jassa cadetta and Elasmopus brasiliensis and the caprellid Caprella hirsuta on drifting objects.

  14. High connectivity across the fragmented chemosynthetic ecosystems of the deep Atlantic Equatorial Belt: efficient dispersal mechanisms or questionable endemism?

    PubMed

    Teixeira, Sara; Olu, Karine; Decker, Carole; Cunha, Regina L; Fuchs, Sandra; Hourdez, Stéphane; Serrão, Ester A; Arnaud-Haond, Sophie

    2013-09-01

    Chemosynthetic ecosystems are distributed worldwide in fragmented habitats harbouring seemingly highly specialized communities. Yet, shared taxa have been reported from highly distant chemosynthetic communities. These habitats are distributed in distinct biogeographical regions, one of these being the so-called Atlantic Equatorial Belt (AEB). Here, we combined genetic data (COI) from several taxa to assess the possible existence of cryptic or synonymous species and to detect the possible occurrence of contemporary gene flow among populations of chemosynthetic species located on both sides of the Atlantic. Several Evolutionary Significant Units (ESUs) of Alvinocarididae shrimp and Vesicomyidae bivalves were found to be shared across seeps of the AEB. Some were also common to hydrothermal vent communities of the Mid-Atlantic Ridge (MAR), encompassing taxa morphologically described as distinct species or even genera. The hypothesis of current or very recent large-scale gene flow among seeps and vents was supported by microsatellite analysis of the shrimp species Alvinocaris muricola/Alvinocaris markensis across the AEB and MAR. Two nonmutually exclusive hypotheses may explain these findings. The dispersion of larvae or adults following strong deep-sea currents, possibly combined with biochemical cues influencing the duration of larval development and timing of metamorphosis, may result in large-scale effective migration among distant spots scattered on the oceanic seafloor. Alternatively, these results may arise from the prevailing lack of knowledge on the ocean seabed, apart from emblematic ecosystems (chemosynthetic ecosystems, coral reefs or seamounts), where the widespread classification of endemism associated with many chemosynthetic taxa might hide wider distributions in overlooked parts of the deep sea. PMID:23927457

  15. Fisheries Closed Areas Strengthen Scallop Larval Settlement and Connectivity Among Closed Areas and Across International Open Fishing Grounds: A Model Study

    NASA Astrophysics Data System (ADS)

    Davies, Kimberley T. A.; Gentleman, W. C.; DiBacco, C.; Johnson, C. L.

    2015-09-01

    This study examined whether a measured increase in average body size of adult sea scallops inside three fishery closed areas on Georges Bank (GB), United States (US), was sufficient to increase larval supply to closed areas and open fishing areas in both US and Canadian areas of the Bank. The effects of adult scallop density-at-size and fecundity-at-size on egg production were compared among open and closed fishery areas, countries, and time periods before and after the closed areas were established. Estimated egg production was then used to define spawning conditions in a coupled biological-physical larval tracking model that simulated larval development, mortality, and dispersal. Results showed that order of magnitude increases in larval settlement after closure were facilitated by increases in size-dependant egg production inside and dispersal from Closed Areas I and II, but not Nantucket Lightship Closed Area. The distributions of both egg production and larval settlement became more uniform across the Bank, causing the relative contribution of Canadian larvae to US scallop aggregations to decrease after establishment of Closed Areas I and II. Decreases in small and medium-sized scallop density in Canada and decreases in large scallops over the US-Southern Flank after closure caused local declines in egg production but were not sufficient to negatively affect larval settlement at the regional scale. Our model suggests that the establishment of fishery closed areas on GB considerably strengthened larval supply and settlement within and among several adult scallop aggregations.

  16. Poor oxic conditions in a large estuary reduce connectivity from marine to freshwater habitats of a diadromous fish

    NASA Astrophysics Data System (ADS)

    Tétard, Stéphane; Feunteun, Eric; Bultel, Elise; Gadais, Romain; Bégout, Marie-Laure; Trancart, Thomas; Lasne, Emilien

    2016-02-01

    Connectivity in aquatic systems is often related to abundance and permeability of physical barriers, such as dams, which delay or impede movements of biota with important consequences for aquatic biodiversity. Water quality may, however, also control connectivity between essential habitats. In macrotidal estuaries, Estuarine Turbidity Maxima (ETM) have a strong impact on water quality because of the low oxygen concentration occurring as a response to the related high bacterial and low photosynthetic activities. In this study, we assess Allis shad estuarine spawning migration in 2011 and 2012 in the Loire River (France) where the ETM occurs at spring and summer. Using an acoustic telemetry array, we show that trans-estuarine migration is inhibited during hypoxic episodes in the middle part of the estuary. Shad tends to stay in downstream areas, and even at sea, where oxygen conditions are more suitable. Trans-estuarine migration occurs hastily during neap tide when the ETM decreases, both in terms of spatial extent and intensity, inducing a shift in a set of covariates including dissolved oxygen, which increases, and suspended matter, which decreases. In the context of climate warming, ETM are expected to increase with probable adverse implications for shad migration success and doubtless other diadromous populations.

  17. Trace determination of antibacterial pharmaceuticals in fishes by microwave-assisted extraction and solid-phase purification combined with dispersive liquid-liquid microextraction followed by ultra-high performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Huang, Peiting; Zhao, Pan; Dai, Xinpeng; Hou, Xiaohong; Zhao, Longshan; Liang, Ning

    2016-02-01

    A novel pretreatment method involving microwave-assisted extraction and solid-phase purification combined with dispersive liquid-liquid microextraction (MAE-SPP-DLLME) followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established for the simultaneous determination of six antibacterial pharmaceuticals including metronidazole, tinidazole, chloramphenicol, thiamphenicol, malachite green and crystal violet. The conditions of MAE were optimized using an orthogonal design and the optimal conditions were found to be 8mL for acetonitrile, 50°C for 5min. Then, neutral alumina column was employed in the solid-phase purification. Finally, the critical parameters affecting DLLME, including selection of extraction and dispersive solvent, adjustment of pH, salt concentration, extraction time, were investigated by single factor study. Under optimum conditions, good linearities (r>0.9991) and satisfied recoveries (Recoveries>87.0%, relative standard deviation (RSD)<6.3%) were observed for all of the target analytes. The limits of detection and quantification were 4.54-101.3pgkg(-1) and 18.02-349.1pgkg(-1), respectively. Intra-day and inter-day RSDs were all lower than 3.6%. An obvious reduction in matrix effect was observed by this method compared with microwave assisted extraction followed by purification. The established method was sensitive, rapid, accurate and employable to simultaneously determine target analytes in farmed fish, river fish and marine fish. PMID:26773891

  18. Toxicity of oil and dispersed oil to the eggs and larvae of seven marine fish and invertebrates from the Gulf of Mexico

    SciTech Connect

    Fucik, K.W.; Carr, K.A.; Balcom, B.J.

    1995-06-01

    The early life stages of seven invertebrate and vertebrate species from the Gulf of Mexico were exposed to two oils, Corexit 9527, and dispersed oil mixtures. Chemical analyses found that hydrocarbon concentrations between exposures were relatively consistent. The hydrocarbon concentrations were initially highest in the dispersed oil mixtures compared to the water accommodated fractions (WAF) of the oils. However, hydrocarbon concentrations in both dispersed oil and WAF exposures were generally similar after 24 hours. The levels of toxicity in the dispersed oil mixtures were not proportionately greater than that in the WAF.

  19. Developing analytical approaches to explore the connection between endocrine-active pharmaceuticals in water to effects in fish

    USGS Publications Warehouse

    Jones-Lepp, Tammy L.; Taniguchi-Fu, Randi L.; Morgan, Jade; Nance Jr., Trevor; Ward, Matthew; Alvarez, David A.; Mills, Lesley

    2015-01-01

    The emphasis of this research project was to develop and optimize a solid-phase extraction method and highperformance liquid chromatography-electrospray ionizationmass spectrometry method, such that a linkage between the detection of endocrine-active pharmaceuticals (EAPs) in the aquatic environment and subsequent effects on fish populations could eventually be studied. Four EAPs were studied: tamoxifen (TAM), exemestane (EXE), letrozole (LET), anastrozole (ANA); and three TAM metabolites: 4- hydroxytamoxifen, e/z endoxifen, and n-desmethyl tamoxifen. In aqueous matrices, the use of isotopically labeled standards for the EAPs allowed for the generation of good recoveries, greater than 80 %, and low relative standard deviations (% RSDs) (3 to 27 %). TAM metabolites had lower recoveries in the spiked water matrices: 35 to 93 % in waste/source water compared to 58 to 110 % in DI water. The precision in DI water was acceptable ranging from 8 to 38 % RSD. However, the precision in real environmental wastewaters could be poor, ranging from 15 to 120 % RSD, dependent upon unique matrix effects. In plasma, the overall recoveries of the EAPs were acceptable: 88 to 110 %, with %RSDs of 6 to 18 % (Table 3). The spiked recoveries of the TAM metabolites from plasma were good, ranging from 77 to 120 %, with %RSDs ranging from 27 to 32 %. Two of the TAM metabolites, 4- hydroxytamoxifen and n-desmethyl tamoxifen, were confirmed in most of the environmental aqueous samples. The discovery of TAM metabolites demonstrates that the source of the TAM metabolites, TAM, is constant, introducing a pseudo-persistence of this chemical into the environment.

  20. Developing analytical approaches to explore the connection between endocrine-active pharmaceuticals in water to effects in fish.

    PubMed

    Jones-Lepp, Tammy L; Taniguchi-Fu, Randi L; Morgan, Jade; Nance, Trevor; Ward, Matthew; Alvarez, David A; Mills, Lesley

    2015-08-01

    The emphasis of this research project was to develop and optimize a solid-phase extraction method and high-performance liquid chromatography-electrospray ionization-mass spectrometry method, such that a linkage between the detection of endocrine-active pharmaceuticals (EAPs) in the aquatic environment and subsequent effects on fish populations could eventually be studied. Four EAPs were studied: tamoxifen (TAM), exemestane (EXE), letrozole (LET), anastrozole (ANA); and three TAM metabolites: 4-hydroxytamoxifen, e/z endoxifen, and n-desmethyl tamoxifen. In aqueous matrices, the use of isotopically labeled standards for the EAPs allowed for the generation of good recoveries, greater than 80 %, and low relative standard deviations (% RSDs) (3 to 27 %). TAM metabolites had lower recoveries in the spiked water matrices: 35 to 93 % in waste/source water compared to 58 to 110 % in DI water. The precision in DI water was acceptable ranging from 8 to 38 % RSD. However, the precision in real environmental wastewaters could be poor, ranging from 15 to 120 % RSD, dependent upon unique matrix effects. In plasma, the overall recoveries of the EAPs were acceptable: 88 to 110 %, with %RSDs of 6 to 18 % (Table 3). The spiked recoveries of the TAM metabolites from plasma were good, ranging from 77 to 120 %, with %RSDs ranging from 27 to 32 %. Two of the TAM metabolites, 4-hydroxytamoxifen and n-desmethyl tamoxifen, were confirmed in most of the environmental aqueous samples. The discovery of TAM metabolites demonstrates that the source of the TAM metabolites, TAM, is constant, introducing a pseudo-persistence of this chemical into the environment. PMID:26077747

  1. Neuroanatomy of pars intercerebralis neurons with special reference to their connections with neurons immunoreactive for pigment-dispersing factor in the blow fly Protophormia terraenovae.

    PubMed

    Yasuyama, Kouji; Hase, Hiroaki; Shiga, Sakiko

    2015-10-01

    Input regions of pars intercerebralis (PI) neurons are examined by confocal and electron microscopies with special reference to their connections with neurons immunoreactive for pigment-dispersing factor (PDF) in the blow fly, Protophormia terraenovae. PI neurons are a prerequisite for ovarian development under long-day conditions. Backfills from the cardiac recurrent nerve after severance of the posterior lateral tracts labeled thin fibers derived from the PI neurons in the superior medial protocerebrum. These PI fibers were mainly synapsin-negative and postsynaptic to unknown varicose profiles containing dense-core vesicles. Backfilled fibers in the periesophageal neuropils, derived from the PI neurons or neurons with somata in the subesophageal zone, were varicose and some were synapsin-positive. Electron microscopy revealed the presence of both presynaptic and postsynaptic sites in backfilled fibers in the periesophageal neuropils. Many PDF-immunoreactive varicosities were found in the superior medial and lateral protocerebrum and double-labeling showed that 60-88 % of PDF-immunoreactive varicosities were also synapsin-immunoreactive. Double-labeling with the backfills and PDF immunocytochemistry showed that the PI fibers and PDF-immunoreactive varicosities were located close to each other in the superior medial protocerebrum. Results of triple-labeling of PI neurons, PDF-immunoreactive neurons and synapsin-immunoreactive terminals demonstrated that the synapsin-positive PDF-immunoreactive varicosities contacted the PI fibers. These data suggest that PI neurons receive synaptic contacts from PDF-immunoreactive fibers, which are derived from circadian clock neurons, of small ventral lateral neurons (previously called OL2) or posterior dorsal (PD) neurons with somata in the pars lateralis. PMID:25971932

  2. Fishing for Seeds.

    ERIC Educational Resources Information Center

    Science and Children, 2001

    2001-01-01

    Describes a method to collect seeds that are dispersed from weeds while avoiding some outdoor hazards such as rough terrain or animals. Describes a plan for creating a weed fishing pole and includes a materials list. (SAH)

  3. Pressure Dependent Mass Fraction in Noble Gas Mass Spectrometers: A Possible Explanation for the Excessive Dispersion in the EARTHTIME Fish Canyon/Alder Creek Inter-Calibration Experiment

    NASA Astrophysics Data System (ADS)

    Turrin, B. D.; Swisher, C. C.; Mana, S.

    2011-12-01

    Mass spectrometer fractionation bias (mass discrimination) is a ubiquitous phenomenon in noble gas mass spectroscopy and must be corrected for in order to obtain accurate-high precision isotopic ratios that are used in isotopic age calculations. Temporal variations in mass fractionation are well known phenomena and have been reported in several studies (eg. Turrin et al., 2010 and references therein). Here we report on the pressure dependency on mass spectrometer fractionation bias. In our experiment, we varied by a factor of five the signal size of aliquots of atmospheric argon delivered from an automated air pipette system. The measured mass discrimination difference (MD) as determined by the 40Ar/36Ar ratio between the 1-fold and 5-fold air pipette shots is ~5%. The air 40Ar/36Ar aliquots were measured using a MAP 215-50 operating in pulse counting mode. The air measurements were interspersed with measurements of Alder Creek (AC) sanidine and Fish Canyon (FC) sanidine that were co-irradiated for 0.75 hours. The grain sizes for the two mineral standards were chosen such that the AC sample yielded 40Ar signals of about 50 kcps, similar to that delivered by a single aliquot delivered by the air pipette. The FC grains were about 5-10 times greater (150-600 kcps) than the single air aliquot. Following the analyses, we applied the MD correction to both the FC and AC analyses. When the MD as determined from the single pipette data (which matches 40Ar beam intensity of the AC sample) is applied to both the AC and FC data a "J" of 1.579±0.001x10-4 is obtained from the FC data and an age of 1183 ±4 ka for AC. However, when the MD as determined from the multiple aliquot pipette data (with an 40Ar beam similar to that of the FC analyses) is applied to the FC data a "J" of 1.588±0.001x10-4 is obtained and an AC age of 1189 ±4 ka the same age at the 95% confidence level, the reported age for AC. We conclude that variation in MD over signal sizes typically analyzed in 40Ar

  4. Inferring the effects of potential dispersal routes on the metacommunity structure of stream insects: as the crow flies, as the fish swims or as the fox runs?

    PubMed

    Kärnä, Olli-Matti; Grönroos, Mira; Antikainen, Harri; Hjort, Jan; Ilmonen, Jari; Paasivirta, Lauri; Heino, Jani

    2015-09-01

    1. Metacommunity research relies largely on proxies for inferring the effect of dispersal on local community structure. Overland and watercourse distances have been typically used as such proxies. A good proxy for dispersal should, however, take into account more complex landscape features that can affect an organism's movement and dispersal. The cost distance approach does just that, allowing determining the path of least resistance across a landscape. 2. Here, we examined the distance decay of assemblage similarity within a subarctic stream insect metacommunity. We tested whether overland, watercourse and cumulative cost distances performed differently as correlates of dissimilarity in assemblage composition between sites. We also investigated the effect of body size and dispersal mode on metacommunity organization. 3. We found that dissimilarities in assemblage composition correlated more strongly with environmental than physical distances between sites. Overland and watercourse distances showed similar correlations to assemblage dissimilarity between sites, being sometimes significantly correlated with biological variation of entire insect communities. In metacommunities deconstructed by body size or dispersal mode, contrary to our expectation, passive dispersers showed a slightly stronger correlation than active dispersers to environmental differences between sites, although passive dispersers also showed a stronger correlation than active dispersers to physical distances between sites. The strength of correlation between environmental distance and biological dissimilarity also varied slightly among the body size classes. 4. After controlling for environmental differences between sites, cumulative cost distances were slightly better correlates of biological dissimilarities than overland or watercourse distances between sites. However, quantitative differences in correlation coefficients were small between different physical distances. 5. Although environmental

  5. Fish Commoditization: Sustainability Strategies to Protect Living Fish

    ERIC Educational Resources Information Center

    Lam, Mimi E.; Pitcher, Tony J.

    2012-01-01

    The impacts of early fishing on aquatic ecosystems were minimal, as primitive technologies were used to harvest fish primarily for food. As fishing technology grew more sophisticated and human populations dispersed and expanded, local economies transitioned from subsistence to barter and trade. Expanded trade networks and mercantilization led to…

  6. Fish community and bioassessment responses to stream network position

    USGS Publications Warehouse

    Hitt, N.P.; Angermeier, P.L.

    2011-01-01

    If organisms move beyond the boundaries of local sampling units, regional metacommunity dynamics could undermine the ability of bioassessment studies to characterize local environmental quality. We tested the prediction that fish dispersal influences local fish community structure and bioassessment metrics as a function of site position within stream networks. We evaluated fish community data from the US Environmental Protection Agency's Regional Environmental Monitoring and Assessment Program in West Virginia, USA, to compare the influences of stream network position, ecoregion, basin, and stream size on local fish community composition. We assigned sites to 1 of 3 stream network positions: 1) main channels (MC, n  =  12) encompassed streams with upstream catchment areas >200 km2, 2) mainstem tributaries (MT, n  =  43) flowed into MC-sized confluences within 15 fluvial km, 3) headwater tributaries (HT, n  =  31) lacked such riverine confluences within 15 fluvial km. MT and HT sites had similar upstream catchment sizes and landuse gradients, but species richness was greater in MT sites than HT sites, whereas MT and MC sites were not different in this regard. Three bioassessment metrics were greater in MT sites than HT sites (intolerant species richness, cyprinid species richness, benthic species richness), but a multimetric index of biotic integrity did not differ among stream network positions. Ordinations revealed that fish community composition was organized primarily by zoogeographic basin (Monongahela River basin, New River basin, Ohio River basin), ecoregion (Central Appalachian Plateau, Western Appalachian Plateau, Ridge and Valley), and stream size. Riverine specialists were more abundant in MT than HT sites and were more abundant in basins connected to the Ohio River than in basins isolated from the Ohio River by a large waterfall (New River). Our results suggest that contemporary dispersal among streams influences fish community composition

  7. Micro-PIXE analysis of trace element variation in otoliths from fish collected near acid mine tailings: Potential for monitoring contaminant dispersal

    NASA Astrophysics Data System (ADS)

    Saquet, M.; Halden, N. M.; Babaluk, J.; Campbell, J. L.; Nejedly, Z.

    2002-04-01

    Otoliths from fish sampled proximal to acid mine tailings located near Sherridon, Manitoba contain elevated abundances of Zn, Mn, Fe and Cu. Sr is also present in amounts ranging from 250 to 1200 ppm with the actual levels dependent on the lake from which fish were taken. Previous work on analyzing Zn and Mn suggests Zn will typically vary between 50 and ˜100 ppm (in marine and non-marine species) and Mn between 10 and ˜100 ppm. Otoliths analyzed in this study contain up to ˜1000 ppm Zn and up to ˜400 ppm Mn; Fe is present, ranging between 50 and 100 ppm and Cu is typically 40-50 ppm. Water samples showed variation in these elements depending on proximity to the tailings.

  8. Genetic population structure of the endemic fourline wrasse (Larabicus quadrilineatus) suggests limited larval dispersal distances in the Red Sea.

    PubMed

    Froukh, Tawfiq; Kochzius, Marc

    2007-04-01

    The connectivity among marine populations is determined by the dispersal capabilities of adults as well as their eggs and larvae. Dispersal distances and directions have a profound effect on gene flow and genetic differentiation within species. Genetic homogeneity over large areas is a common feature of coral reef fishes and can reflect high dispersal capability resulting in high levels of gene flow. If fish larvae return to their parental reef, gene flow would be restricted and genetic differentiation could occur. Larabicus quadrilineatus (Labridae) is considered as an endemic fish species of the Red Sea and Gulf of Aden. The juveniles of this species are cleaner fish that feed on ectoparasites of other fishes. Here, we investigated the genetic population structure and gene flow in L. quadrilineatus among five locations in the Red Sea to infer connectivity among them. To estimate genetic diversity, we analysed 369 bp of 237 mitochondrial DNA control region sequences. Haplotype and nucleotide diversities were higher in the southern than in the northern Red Sea. Analysis of molecular variance (amova) detected the highest significant genetic variation between northern and central/southern populations (Phi(CT) = 0.01; P < 0.001). Migration analysis revealed a several fold higher northward than southward migration, which could be explained by oceanographic conditions and spawning season. Even though the Phi(ST) value of 0.01 is rather low and implies a long larval dispersal distance, estimates based on the isolation-by-distance model show a very low mean larval dispersal distance (0.44-5.1 km) compared to other studies. In order to enable a sustainable ornamental fishery on the fourline wrasse, the results of this study suggest that populations in the northern and southern Red Sea should be managed separately as two different stocks. The rather low larval dispersal distance of about 5 km needs to be considered in the design of marine protected areas to enable

  9. Is dispersal neutral?

    PubMed

    Lowe, Winsor H; McPeek, Mark A

    2014-08-01

    Dispersal is difficult to quantify and often treated as purely stochastic and extrinsically controlled. Consequently, there remains uncertainty about how individual traits mediate dispersal and its ecological effects. Addressing this uncertainty is crucial for distinguishing neutral versus non-neutral drivers of community assembly. Neutral theory assumes that dispersal is stochastic and equivalent among species. This assumption can be rejected on principle, but common research approaches tacitly support the 'neutral dispersal' assumption. Theory and empirical evidence that dispersal traits are under selection should be broadly integrated in community-level research, stimulating greater scrutiny of this assumption. A tighter empirical connection between the ecological and evolutionary forces that shape dispersal will enable richer understanding of this fundamental process and its role in community assembly. PMID:24962790

  10. Evidence of stable genetic structure across a remote island archipelago through self-recruitment in a widely dispersed coral reef fish

    PubMed Central

    Priest, Mark A; Halford, Andrew R; McIlwain, Jennifer L

    2012-01-01

    We used microsatellite markers to assess the population genetic structure of the scribbled rabbitfish Siganus spinus in the western Pacific. This species is a culturally important food fish in the Mariana Archipelago and subject to high fishing pressure. Our primary hypothesis was to test whether the individuals resident in the southern Mariana Island chain were genetically distinct and hence should be managed as discrete stocks. In addition to spatial sampling of adults, newly-settled individuals were sampled on Guam over four recruitment events to assess the temporal stability of the observed spatial patterns, and evidence of self-recruitment. We found significant genetic structure in S. spinus across the western Pacific, with Bayesian analyses revealing three genetically distinct clusters: the southern Mariana Islands, east Micronesia, and the west Pacific; with the southern Mariana Islands being more strongly differentiated from the rest of the region. Analyses of temporal samples from Guam indicated the southern Mariana cluster was stable over time, with no genetic differentiation between adults versus recruits, or between samples collected across four separate recruitment events spanning 11 months. Subsequent assignment tests indicated seven recruits had self-recruited from within the Southern Mariana Islands population. Our results confirm the relative isolation of the southern Mariana Islands population and highlight how local processes can act to isolate populations that, by virtue of their broad-scale distribution, have been subject to traditionally high gene flows. Our results add to a growing consensus that self-recruitment is a highly significant influence on the population dynamics of tropical reef fish. PMID:23301184

  11. Population Connectivity Shifts at High Frequency within an Open-Coast Marine Protected Area Network

    PubMed Central

    Cook, Geoffrey S.; Parnell, P. Ed; Levin, Lisa A.

    2014-01-01

    A complete understanding of population connectivity via larval dispersal is of great value to the effective design and management of marine protected areas (MPA). However empirical estimates of larval dispersal distance, self-recruitment, and within season variability of population connectivity patterns and their influence on metapopulation structure remain rare. We used high-resolution otolith microchemistry data from the temperate reef fish Hypsypops rubicundus to explore biweekly, seasonal, and annual connectivity patterns in an open-coast MPA network. The three MPAs, spanning 46 km along the southern California coastline were connected by larval dispersal, but the magnitude and direction of connections reversed between 2008 and 2009. Self-recruitment, i.e. spawning, dispersal, and settlement to the same location, was observed at two locations, one of which is a MPA. Self-recruitment to this MPA ranged from 50–84%; within the entire 60 km study region, self-recruitment accounted for 45% of all individuals settling to study reefs. On biweekly time scales we observed directional variability in alongshore current data and larval dispersal trajectories; if viewed in isolation these data suggest the system behaves as a source-sink metapopulation. However aggregate biweekly data over two years reveal a reef network in which H. rubicundus behaves more like a well-mixed metapopulation. As one of the few empirical studies of population connectivity within a temperate open coast reef network, this work can inform the MPA design process, implementation of ecosystem based management plans, and facilitate conservation decisions. PMID:25077486

  12. A Tale of Two Anomalies: Depletion, Dispersion, and the Connection between the Stellar Lithium Spread and Inflated Radii on the Pre-main Sequence

    NASA Astrophysics Data System (ADS)

    Somers, Garrett; Pinsonneault, Marc H.

    2014-07-01

    We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Li abundance at fixed T eff is nearly universal, and sets in by ~200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the spread in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius anomalies in magnetically active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.

  13. A tale of two anomalies: Depletion, dispersion, and the connection between the stellar lithium spread and inflated radii on the pre-main sequence

    SciTech Connect

    Somers, Garrett; Pinsonneault, Marc H. E-mail: pinsono@astronomy.ohio-state.edu

    2014-07-20

    We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Li abundance at fixed T{sub eff} is nearly universal, and sets in by ∼200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the spread in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius anomalies in magnetically active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.

  14. Oil dispersants

    SciTech Connect

    Flaherty, L.M.

    1989-01-01

    This book contains papers presented at a symposium of the American Society for Testing and Materials. The topics covered include: The effect of elastomers on the efficiency of oil spill dispersants; planning for dispersant use; field experience with dispersants for oil spills on land; and measurements on natural dispersion.

  15. Fish Allergy

    MedlinePlus

    ... Story" 5 Things to Know About Zika & Pregnancy Fish Allergy KidsHealth > For Parents > Fish Allergy Print A ... From Home en español Alergia al pescado About Fish Allergy A fish allergy is not exactly the ...

  16. Changes in the fish fauna of the Kissimmee River basin, peninsular Florida: Nonnative additions

    USGS Publications Warehouse

    Nico, L.G.

    2005-01-01

    Recent decades have seen substantial changes in fish assemblages in rivers of peninsular Florida. The most striking change has involved the addition of nonnative fishes, including taxa from Asia, Africa, and Central and South America. I review recent and historical records of fishes occurring in the Kissimmee River basin (7,800 km2), a low-gradient drainage with 47 extant native fishes (one possibly the result of an early transplant), at least 7 foreign fishes (most of which are widely established), and a stocked hybrid. Kissimmee assemblages include fewer marine fishes than the nearby Peace and Caloosahatchee rivers, and fewer introduced foreign fishes than south Florida canals. Fish assemblages of the Kissimmee and other subtropical Florida rivers are dynamic, due to new introductions, range expansions of nonnative fishes already present, and periodic declines in nonnative fish populations during occasional harsh winters. The addition, dispersal, and abundance of nonnative fishes in the basin is linked to many factors, including habitat disturbance, a subtropical climate, and the fact that the basin is centrally located in a region where drainage boundaries are blurred and introductions of foreign fishes commonplace. The first appearance of foreign fishes in the basin coincided with the complete channelization of the Kissimmee River in the 1970s. Although not a causal factor, artificial waterways connecting the upper lakes and channelization of the Kissimmee River have facilitated dispersal. With one possible exception, there have been no basin-wide losses of native fishes. When assessing change in peninsular Florida waters, extinction or extirpation of fishes appears to be a poor measure of impact. No endemic species are known from peninsular Florida (although some endemic subspecies have been noted). Most native freshwater fishes are themselves descended from recent invaders that reached the peninsula from the main continent. These invasions likely were

  17. Population connectivity of deep-sea corals: Chapter 12

    USGS Publications Warehouse

    Morrison, Cheryl L.; Baco, Amy; Nizinski, Martha S.; Coykendall, Dolly K.; Demopoulos, Amanda W. J.; Cho, Walter; Shank, Tim

    2015-01-01

    Identifying the scale of dispersal among habitats has been a challenge in marine ecology for decades (Grantham et al., 2003; Kinlan & Gaines, 2003; Hixon, 2011). Unlike terrestrial habitats in which barriers to dispersal may be obvious (e.g. mountain ranges, rivers), few absolute barriers to dispersal are recognizable in the sea. Additionally, most marine species have complex life cycles in which juveniles are more mobile than adults. As such, the dynamics of populations may involve processes in distant habitats that are coupled by a transport mechanism. Studies of population connectivity try to quantify the transport, or dispersal of individuals, among geographically separated populations. For benthic marine species, such as corals and demersal fishes, colonization of new populations occurs primarily by dispersal of larvae (Figure 1; Shank, 2010). Successful dispersal and recruitment, followed by maturation and reproduction of these new migrants ensures individuals contribute to the gene pool (Hedgecock, 2007). Thus, successful dispersal links and cohesively maintains spatially separated sub-populations. At shorter time scales (10-100s years), connectivity regulates community structure by influencing the genetic composition, diversity and demographic stability of the population, whereas at longer time scales (1000s years), geographic distributions are affected (McClain and Hardy, 2010). Alternatively, populations may become extinct or speciation may occur if connectivity ceases (Cowen et al., 2007). Therefore, the genetic exchange of individuals between populations is fundamental to the short-term resilience and long-term maintenance of the species. However, for the vast majority of marine species, population connectivity remains poorly understood.

  18. One Fish Two Fish.

    ERIC Educational Resources Information Center

    Hoffman, Michele

    1998-01-01

    This activity explains fisheries resource management to seven-year olds. First-grade students learn concepts such as offspring viability, life expectancy, and distribution of species, which help to determine when, where, and how people fish and the importance of fishing responsibly. Lists materials, procedures, and extensions. (SJR)

  19. To what extent do human-altered landscapes retain population connectivity? Historical changes in gene flow of wetland fish Pungitius pungitius.

    PubMed

    Ishiyama, N; Sueyoshi, M; Nakamura, F

    2015-07-01

    Understanding how human-altered landscapes affect population connectivity is valuable for conservation planning. Natural connectivity among wetlands, which is maintained by floods, is disappearing owing to farmland expansion. Using genetic data, we assessed historical changes in the population connectivity of the ninespine stickleback within a human-altered wetland system. We predicted that: (i) the contemporary gene flow maintained by the artificial watercourse network may be restricted to a smaller spatial scale compared with the gene flow preceding alteration, and (ii) the contemporary gene flow is dominated by the downstream direction owing to the construction of low-head barriers. We evaluated the potential source population in both timescales. Seventeen studied populations were grouped into four genetically different clusters, and we estimated the migration rates among these clusters. Contemporary migration was restricted to between neighbouring clusters, although a directional change was not detected. Furthermore, we consistently found the same potential source cluster, from past to present, characterized by large amounts of remnant habitats connected by artificial watercourses. These findings highlight that: (i) artificial connectivity can sustain the short-distance connectivity of the ninespine stickleback, which contributes to maintaining the potential source populations; however, (ii) population connectivity throughout the landscape has been prevented by agricultural developments. PMID:26587264

  20. To what extent do human-altered landscapes retain population connectivity? Historical changes in gene flow of wetland fish Pungitius pungitius

    PubMed Central

    Ishiyama, N.; Sueyoshi, M.; Nakamura, F.

    2015-01-01

    Understanding how human-altered landscapes affect population connectivity is valuable for conservation planning. Natural connectivity among wetlands, which is maintained by floods, is disappearing owing to farmland expansion. Using genetic data, we assessed historical changes in the population connectivity of the ninespine stickleback within a human-altered wetland system. We predicted that: (i) the contemporary gene flow maintained by the artificial watercourse network may be restricted to a smaller spatial scale compared with the gene flow preceding alteration, and (ii) the contemporary gene flow is dominated by the downstream direction owing to the construction of low-head barriers. We evaluated the potential source population in both timescales. Seventeen studied populations were grouped into four genetically different clusters, and we estimated the migration rates among these clusters. Contemporary migration was restricted to between neighbouring clusters, although a directional change was not detected. Furthermore, we consistently found the same potential source cluster, from past to present, characterized by large amounts of remnant habitats connected by artificial watercourses. These findings highlight that: (i) artificial connectivity can sustain the short-distance connectivity of the ninespine stickleback, which contributes to maintaining the potential source populations; however, (ii) population connectivity throughout the landscape has been prevented by agricultural developments. PMID:26587264

  1. Stress dependent dispersion relations of acoustic waves travelling on a chain of point masses connected by anharmonic linear and torsional springs

    NASA Astrophysics Data System (ADS)

    Pluta, Mieczysław; Amjad, Umar; Klinghammer, Hermann; Jha, Diwaker; Tarar, Khurram; Grill, Wolfgang

    2012-05-01

    The propagation of a deformation along a flexural beam or plate depends on material properties, geometrical conditions like the beam cross-section, effects of stiffening or softening due to external stress, and last but not least the mode of the wave including its polarization. The time-of-flight (TOF) of acoustic waves is influenced by any of the above listed parameters. This effect is utilized in ultrasonic NDE and structural health monitoring applications. It was shown in earlier publications that the solutions of wave equations for a linear chain model consisting of identical mass points, subject to a direction and distance dependent potential, show the dispersion properties and dependencies on externally applied stress of the lowest longitudinal and transversal plate modes. In the model presented here anharmonic potentials are introduced. The potentials are represented by torsional springs at each mass point and linear springs between them. Dynamic equations are derived, based on interactions with next and second next neighbors. The results obtained with the developed model are compared with experimental observations concerning the reaction of the TOF for the lowest Lamb modes in an aluminum plate under variable in plane stress. The developed models are capable to demonstrate general aspects of the mode and frequency dependence of the acousto-elastic coefficients for the lowest symmetric and antisymmetric Lamb waves. The introduced anharmonicities allow furthermore for a close approximation of the experimental findings.

  2. Fish Hearing.

    ERIC Educational Resources Information Center

    Blaxter, J. H. S.

    1980-01-01

    Provides related information about hearing in fish, including the sensory stimulus of sound in the underwater environment, mechanoreceptors in fish, pressure perception and the swimbladder, specializations in sound conduction peculiar to certain fish families. Includes numerous figures. (CS)

  3. City Fishing.

    ERIC Educational Resources Information Center

    Lange, Robert E.

    1979-01-01

    A program of supplying opportunities for fishing at locations within and near urban areas was developed. This effort included stocking, management of bodies of water for fishing, and presentation of fishing clinics for urban fishermen. (RE)

  4. Broad-scale sampling of primary freshwater fish populations reveals the role of intrinsic traits, inter-basin connectivity, drainage area and latitude on shaping contemporary patterns of genetic diversity

    PubMed Central

    Robalo, Joana I.; Pereira, Ana M.; Branco, Paulo; Santos, José Maria; Ferreira, Maria Teresa; Sousa, Mónica; Doadrio, Ignacio

    2016-01-01

    Background. Worldwide predictions suggest that up to 75% of the freshwater fish species occurring in rivers with reduced discharge could be extinct by 2070 due to the combined effect of climate change and water abstraction. The Mediterranean region is considered to be a hotspot of freshwater fish diversity but also one of the regions where the effects of climate change will be more severe. Iberian cyprinids are currently highly endangered, with over 68% of the species raising some level of conservation concern. Methods. During the FISHATLAS project, the Portuguese hydrographical network was extensively covered (all the 34 river basins and 47 sub-basins) in order to contribute with valuable data on the genetic diversity distribution patterns of native cyprinid species. A total of 188 populations belonging to 16 cyprinid species of Squalius, Luciobarbus, Achondrostoma, Iberochondrostoma, Anaecypris and Pseudochondrostoma were characterized, for a total of 3,678 cytochrome b gene sequences. Results. When the genetic diversity of these populations was mapped, it highlighted differences among populations from the same species and between species with identical distribution areas. Factors shaping the contemporary patterns of genetic diversity were explored and the results revealed the role of latitude, inter-basin connectivity, migratory behaviour, species maximum size, species range and other species intrinsic traits in determining the genetic diversity of sampled populations. Contrastingly, drainage area and hydrological regime (permanent vs. temporary) seem to have no significant effect on genetic diversity. Species intrinsic traits, maximum size attained, inter-basin connectivity and latitude explained over 30% of the haplotype diversity variance and, generally, the levels of diversity were significantly higher for smaller sized species, from connected and southerly river basins. Discussion. Targeting multiple co-distributed species of primary freshwater fish allowed

  5. Broad-scale sampling of primary freshwater fish populations reveals the role of intrinsic traits, inter-basin connectivity, drainage area and latitude on shaping contemporary patterns of genetic diversity.

    PubMed

    Sousa-Santos, Carla; Robalo, Joana I; Pereira, Ana M; Branco, Paulo; Santos, José Maria; Ferreira, Maria Teresa; Sousa, Mónica; Doadrio, Ignacio

    2016-01-01

    Background. Worldwide predictions suggest that up to 75% of the freshwater fish species occurring in rivers with reduced discharge could be extinct by 2070 due to the combined effect of climate change and water abstraction. The Mediterranean region is considered to be a hotspot of freshwater fish diversity but also one of the regions where the effects of climate change will be more severe. Iberian cyprinids are currently highly endangered, with over 68% of the species raising some level of conservation concern. Methods. During the FISHATLAS project, the Portuguese hydrographical network was extensively covered (all the 34 river basins and 47 sub-basins) in order to contribute with valuable data on the genetic diversity distribution patterns of native cyprinid species. A total of 188 populations belonging to 16 cyprinid species of Squalius, Luciobarbus, Achondrostoma, Iberochondrostoma, Anaecypris and Pseudochondrostoma were characterized, for a total of 3,678 cytochrome b gene sequences. Results. When the genetic diversity of these populations was mapped, it highlighted differences among populations from the same species and between species with identical distribution areas. Factors shaping the contemporary patterns of genetic diversity were explored and the results revealed the role of latitude, inter-basin connectivity, migratory behaviour, species maximum size, species range and other species intrinsic traits in determining the genetic diversity of sampled populations. Contrastingly, drainage area and hydrological regime (permanent vs. temporary) seem to have no significant effect on genetic diversity. Species intrinsic traits, maximum size attained, inter-basin connectivity and latitude explained over 30% of the haplotype diversity variance and, generally, the levels of diversity were significantly higher for smaller sized species, from connected and southerly river basins. Discussion. Targeting multiple co-distributed species of primary freshwater fish allowed

  6. Fish elevator and method of elevating fish

    DOEpatents

    Truebe, Jonathan; Drooker, Michael S.

    1984-01-01

    A means and method for transporting fish from a lower body of water to a higher body of water. The means comprises a tubular lock with a gated entrance below the level of the lower body of water through which fish may enter the lock and a discharge passage above the level of the upper body of water. The fish raising means in the lock is a crowder pulled upward by a surface float as water from the upper body of water gravitationally flows into the closed lock filling it to the level of the upper body. Water is then pumped into the lock to raise the level to the discharge passage. The crowder is then caused to float upward the remaining distance through the water to the level of the discharge passage by the introduction of air into a pocket on the underside of the crowder. The fish are then automatically discharged from the lock into the discharge passage by the out of water position of the crowder. The movement of the fish into the discharge passage is aided by the continuous overflow of water still being pumped into the lock. A pipe may be connected to the discharge passage to deliver the fish to a selected location in the upper body of water.

  7. A synthesis of genetic connectivity in deep-sea fauna and implications for marine reserve design.

    PubMed

    Baco, Amy R; Etter, Ron J; Ribeiro, Pedro A; von der Heyden, Sophie; Beerli, Peter; Kinlan, Brian P

    2016-07-01

    With anthropogenic impacts rapidly advancing into deeper waters, there is growing interest in establishing deep-sea marine protected areas (MPAs) or reserves. Reserve design depends on estimates of connectivity and scales of dispersal for the taxa of interest. Deep-sea taxa are hypothesized to disperse greater distances than shallow-water taxa, which implies that reserves would need to be larger in size and networks could be more widely spaced; however, this paradigm has not been tested. We compiled population genetic studies of deep-sea fauna and estimated dispersal distances for 51 studies using a method based on isolation-by-distance slopes. Estimates of dispersal distance ranged from 0.24 km to 2028 km with a geometric mean of 33.2 km and differed in relation to taxonomic and life-history factors as well as several study parameters. Dispersal distances were generally greater for fishes than invertebrates with the Mollusca being the least dispersive sampled phylum. Species that are pelagic as adults were more dispersive than those with sessile or sedentary lifestyles. Benthic species from soft-substrate habitats were generally less dispersive than species from hard substrate, demersal or pelagic habitats. As expected, species with pelagic and/or feeding (planktotrophic) larvae were more dispersive than other larval types. Many of these comparisons were confounded by taxonomic or other life-history differences (e.g. fishes being more dispersive than invertebrates) making any simple interpretation difficult. Our results provide the first rough estimate of the range of dispersal distances in the deep sea and allow comparisons to shallow-water assemblages. Overall, dispersal distances were greater for deeper taxa, although the differences were not large (0.3-0.6 orders of magnitude between means), and imbalanced sampling of shallow and deep taxa complicates any simple interpretation. Our analyses suggest the scales of dispersal and connectivity for reserve design

  8. Transgenic Fish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fish into which foreign DNA is artificially introduced and integrated into their genome are called transgenic fish. Since the development of the first transgenic fish in 1985, techniques to produce transgenic fish have improved tremendously, resulting in the production of genetically modified (GM) ...

  9. Ocular dispersion

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Noojin, Gary D.; Thomas, Robert J.; Stolarski, David J.; Rockwell, Benjamin A.; Welch, Ashley J.

    1999-06-01

    Spectrally resolved white-light interferometry (SRWLI) was used to measure the wavelength dependence of refractive index (i.e., dispersion) for various ocular components. The accuracy of the technique was assessed by measurement of fused silica and water, the refractive indices of which have been measured at several different wavelengths. The dispersion of bovine and rabbit aqueous and vitreous humor was measured from 400 to 1100 nm. Also, the dispersion was measured from 400 to 700 nm for aqueous and vitreous humor extracted from goat and rhesus monkey eyes. For the humors, the dispersion did not deviate significantly from water. In an additional experiment, the dispersion of aqueous and vitreous humor that had aged up to a month was compared to freshly harvested material. No difference was found between the fresh and aged media. An unsuccessful attempt was also made to use the technique for dispersion measurement of bovine cornea and lens. Future refinement may allow measurement of the dispersion of cornea and lens across the entire visible and near-infrared wavelength band. The principles of white- light interferometry including image analysis, measurement accuracy, and limitations of the technique, are discussed. In addition, alternate techniques and previous measurements of ocular dispersion are reviewed.

  10. Ecological speciation in tropical reef fishes

    PubMed Central

    Rocha, Luiz A; Robertson, D. Ross; Roman, Joe; Bowen, Brian W

    2005-01-01

    The high biodiversity in tropical seas provides a long-standing challenge to allopatric speciation models. Physical barriers are few in the ocean and larval dispersal is often extensive, a combination that should reduce opportunities for speciation. Yet coral reefs are among the most species-rich habitats in the world, indicating evolutionary processes beyond conventional allopatry. In a survey of mtDNA sequences of five congeneric west Atlantic reef fishes (wrasses, genus Halichoeres) with similar dispersal potential, we observed phylogeographical patterns that contradict expectations of geographical isolation, and instead indicate a role for ecological speciation. In Halichoeres bivittatus and the species pair Halichoeres radiatus/brasiliensis, we observed strong partitions (3.4% and 2.3% divergence, respectively) between adjacent and ecologically distinct habitats, but high genetic connectivity between similar habitats separated by thousands of kilometres. This habitat partitioning is maintained even at a local scale where H. bivittatus lineages are segregated between cold- and warm-water habitats in both Bermuda and Florida. The concordance of evolutionary partitions with habitat types, rather than conventional biogeographical barriers, indicates parapatric ecological speciation, in which adaptation to alternative environmental conditions in adjacent locations overwhelms the homogenizing effect of dispersal. This mechanism can explain the long-standing enigma of high biodiversity in coral reef faunas. PMID:15817431

  11. Fish Dishes.

    ERIC Educational Resources Information Center

    Derby, Marie

    2003-01-01

    Describes an art project that was inspired by Greek pottery, specifically dishes shaped as fish. Explains that fourth-grade students drew a fish shape that was later used to create their clay version of the fish. Discusses how the students examined the pottery to make decisions about color and design. (CMK)

  12. Dispersion Modeling.

    ERIC Educational Resources Information Center

    Budiansky, Stephen

    1980-01-01

    This article discusses the need for more accurate and complete input data and field verification of the various models of air pollutant dispension. Consideration should be given to changing the form of air quality standards based on enhanced dispersion modeling techniques. (Author/RE)

  13. Fish Rhabdoviruses

    USGS Publications Warehouse

    Kurath, G.; Winton, J.

    2008-01-01

    Many important viral pathogens of fish are members of the family Rhabdoviridae. The viruses in this large group cause significant losses in populations of wild fish as well as among fish reared in aquaculture. Fish rhabdoviruses often have a wide host and geographic range, and infect aquatic animals in both freshwater and seawater. The fish rhabdoviruses comprise a diverse collection of isolates that can be placed in one of two quite different groups: isolates that are members of the established genusNovirhabdovirus, and those that are most similar to members of the genus Vesiculovirus. Because the diseases caused by fish rhabdoviruses are important to aquaculture, diagnostic methods for their detection and identification are well established. In addition to regulations designed to reduce the spread of fish viruses, a significant body of research has addressed methods for the control or prevention of diseases caused by fish rhabdoviruses, including vaccination. The number of reported fish rhabdoviruses continues to grow as a result of the expansion of aquaculture, the increase in global trade, the development of improved diagnostic methods, and heightened surveillance activities. Fish rhabdoviruses serve as useful components of model systems to study vertebrate virus disease, epidemiology, and immunology.

  14. Fish flavor.

    PubMed

    Kawai, T

    1996-02-01

    This article reviews features of flavor in three groups of fishes and summarizes them as follows: (1) fresh saltwater fish are nearly odorless because they contain a small quantity of volatiles; (2 freshwater fish give off pyrrolidine and earthy-odor compounds, which are responsible for their maturity and surrounding water pollution, and (3) euryhaline fish exhibit a variety of unsaturated carbonyls and alcohols derived from enzymatic and nonenzymatic oxidation of polyunsaturated fatty acids (PAs). These features are discussed, as are the effects of different enzymatic activities on PA oxidation and the effects of pH on mechanisms of formation of the volatiles. The monotonous volatile constitution of saltwater fish is likely caused by an unknown antioxidation system restraining the fish from oxidizing. The variety of constitution of euryhaline fish, especially that of anadromous fish under spawning conditions, could result from the loss of that system. The thermal environments of heated foods are also reviewed. The basic environment of fish, which allows the formation of flavor compounds, is discussed to confirm the volatiles found in unheated fish. PMID:8744606

  15. Observations of the distributions of five fish species in a small Appalachian stream

    USGS Publications Warehouse

    Larson, Gary L.; Hoffman, Robert L.; Moore, S.E.

    2002-01-01

    The notion has been growing that resident stream fishes exhibit a greater capacity for movement than was previously thought. In this study, we recorded the distributions of four resident fish species (longnose dace Rhinichthys cataractae, blacknose dace R. atratulus, mottled sculpin Cottus bairdi, and rainbow trout Oncorhynchus mykiss) and one nonresident species (central stoneroller Campostoma anomalum) in Rock Creek, a small tributary of Cosby Creek in Great Smoky Mountains National Park, over the period 1979a??1995. During this study, 1,998 individuals of resident species were collected from stream sections considered to be within a common area of distribution for each species. Forty-five individuals of resident and nonresident species were captured upstream of these areas, and eight of these fish were considered to be larger than individuals considered typical for each species. Small mammal dispersal theory concepts were used to classify and describe fish movements outside of common areas of distribution. These movements were identified as important in maintaining population connectivity within stream drainages, contributing to reducing the potential for local extinctions of populations and to the recolonization of unoccupied habitats. This study highlights the need for continued study of fish movements in stream drainages and for development of appropriate resource management strategies based partly on the spatial dynamics of fish populations and communities.

  16. Fog dispersion

    NASA Technical Reports Server (NTRS)

    Frost, W.; Christensen, L. S.; Collins, F. G.; Camp, D. W.

    1980-01-01

    A study of economically viable techniques for dispersing warm fog at commercial airports is presented. Five fog dispersion techniques are examined: evaporation suppression, downwash, mixing, seeding with hygroscopic material, thermal techniques, and charged particle techniques. Thermal techniques, although effective, were found to be too expensive for routine airport operations, and detrimental to the environment. Seeding or helicopter downwash are practical for small-scale or temporary fog clearing, but are probably not useful for airport operations on a routine basis. Considerable disagreement exists on the capability of charged particle techniques, which stems from the fact that different assumptions and parameter values are used in the analytical models. Recommendations resulting from the review of this technique are listed, and include: experimental measurements of the parameters in question; a study to ascertain possible safety hazards, such as increased electrical activity or fuel ignition during refueling operations which could render charged particle techniques impractical; and a study of a single charged particle generator.

  17. Consequences of variable larval dispersal pathways and resulting phenotypic mixtures to the dynamics of marine metapopulations

    PubMed Central

    Shima, Jeffrey S.; Noonburg, Erik G.; Swearer, Stephen E.

    2015-01-01

    Larval dispersal can connect distant subpopulations, with important implications for marine population dynamics and persistence, biodiversity conservation and fisheries management. However, different dispersal pathways may affect the final phenotypes, and thus the performance and fitness of individuals that settle into subpopulations. Using otolith microchemical signatures that are indicative of ‘dispersive’ larvae (oceanic signatures) and ‘non-dispersive’ larvae (coastal signatures), we explore the population-level consequences of dispersal-induced variability in phenotypic mixtures for the common triplefin (a small reef fish). We evaluate lipid concentration and otolith microstructure and find that ‘non-dispersive’ larvae (i) have greater and less variable lipid reserves at settlement (and this variability attenuates at a slower rate), (ii) grow faster after settlement, and (iii) experience similar carry-over benefits of lipid reserves on post-settlement growth relative to ‘dispersive’ larvae. We then explore the consequences of phenotypic mixtures in a metapopulation model with two identical subpopulations replenished by variable contributions of ‘dispersive’ and ‘non-dispersive’ larvae and find that the resulting phenotypic mixtures can have profound effects on the size of the metapopulation. We show that, depending upon the patterns of connectivity, phenotypic mixtures can lead to larger metapopulations, suggesting dispersal-induced demographic heterogeneity may facilitate metapopulation persistence. PMID:25673001

  18. Adsorption and removal of graphene dispersants.

    PubMed

    Irin, Fahmida; Hansen, Matthew J; Bari, Rozana; Parviz, Dorsa; Metzler, Shane D; Bhattacharia, Sanjoy K; Green, Micah J

    2015-05-15

    We demonstrate three different techniques (dialysis, vacuum filtration, and spray drying) for removal of dispersants from liquid-exfoliated graphene. We evaluate these techniques for elimination of dispersants from both the bulk liquid phase and from the graphene surface. Thermogravimetric analysis (TGA) confirms dispersant removal by these treatments. Vacuum filtration (driving by convective mass transfer) is the most effective method of dispersant removal, regardless of the type of dispersant, removing up to ∼95 wt.% of the polymeric dispersant with only ∼7.4 wt.% decrease in graphene content. Dialysis also removes a significant fraction (∼70 wt.% for polymeric dispersants) of un-adsorbed dispersants without disturbing the dispersion quality. Spray drying produces re-dispersible, crumpled powder samples and eliminates much of the unabsorbed dispersants. We also show that there is no rapid desorption of dispersants from the graphene surface. In addition, electrical conductivity measurements demonstrate conductivities one order of magnitude lower for graphene drop-cast films (where excess dispersants are present) than for vacuum filtered films, confirming poor inter-sheet connectivity when excess dispersants are present. PMID:25681785

  19. Texture Fish

    ERIC Educational Resources Information Center

    Stone, Julie

    2007-01-01

    In an effort to provide an opportunity for her first graders to explore texture through an engaging subject, the author developed a three-part lesson that features fish in a mixed-media artwork: (1) Exploring Textured Paint; (2) Creating the Fish; and (3) Role Playing. In this lesson, students effectively explore texture through painting, drawing,…

  20. Larval connectivity in an effective network of marine protected areas.

    PubMed

    Christie, Mark R; Tissot, Brian N; Albins, Mark A; Beets, James P; Jia, Yanli; Ortiz, Delisse M; Thompson, Stephen E; Hixon, Mark A

    2010-01-01

    Acceptance of marine protected areas (MPAs) as fishery and conservation tools has been hampered by lack of direct evidence that MPAs successfully seed unprotected areas with larvae of targeted species. For the first time, we present direct evidence of large-scale population connectivity within an existing and effective network of MPAs. A new parentage analysis identified four parent-offspring pairs from a large, exploited population of the coral-reef fish Zebrasoma flavescens in Hawai'i, revealing larval dispersal distances ranging from 15 to 184 km. In two cases, successful dispersal was from an MPA to unprotected sites. Given high adult abundances, the documentation of any parent-offspring pairs demonstrates that ecologically-relevant larval connectivity between reefs is substantial. All offspring settled at sites to the north of where they were spawned. Satellite altimetry and oceanographic models from relevant time periods indicated a cyclonic eddy that created prevailing northward currents between sites where parents and offspring were found. These findings empirically demonstrate the effectiveness of MPAs as useful conservation and management tools and further highlight the importance of coupling oceanographic, genetic, and ecological data to predict, validate and quantify larval connectivity among marine populations. PMID:21203576

  1. Adaption of egg and larvae sampling techniques for lake sturgeon and broadcast spawning fishes in a deep river

    USGS Publications Warehouse

    Roseman, Edward F.; Kennedy, Gregory W.; Craig, Jaquelyn; Boase, James; Soper, Karen

    2011-01-01

    In this report we describe how we adapted two techniques for sampling lake sturgeon (Acipenser fulvescens) and other fish early life history stages to meet our research needs in the Detroit River, a deep, flowing Great Lakes connecting channel. First, we developed a buoy-less method for sampling fish eggs and spawning activity using egg mats deployed on the river bottom. The buoy-less method allowed us to fish gear in areas frequented by boaters and recreational anglers, thus eliminating surface obstructions that interfered with recreational and boating activities. The buoy-less method also reduced gear loss due to drift when masses of floating aquatic vegetation would accumulate on buoys and lines, increasing the drag on the gear and pulling it downstream. Second, we adapted a D-frame drift net system formerly employed in shallow streams to assess larval lake sturgeon dispersal for use in the deeper (>8 m) Detroit River using an anchor and buoy system.

  2. Evaluation of rockfish conservation area networks in the United States and Canada relative to the dispersal distance for black rockfish (Sebastes melanops)

    PubMed Central

    Lotterhos, Katie E; Dick, Stefan J; Haggarty, Dana R

    2014-01-01

    Marine reserves networks are implemented as a way to mitigate the impact of fishing on marine ecosystems. Theory suggests that a reserve network will function synergistically when connected by dispersal, but the scale of dispersal is often unknown. On the Pacific coast of the United States and Canada, both countries have recently implemented a number of rockfish conservation areas (RCAs) to protect exploited rockfish species, but no study has evaluated the connectivity within networks in each country or between the two countries. We used isolation-by-distance theory to estimate the scale of dispersal from microsatellite data in the black rockfish, Sebastes melanops, and compared this estimate with the distance between RCAs that would protect this species. Within each country, we found that the distance between RCAs was generally within the confidence intervals of mean dispersal per generation. The distance between these two RCA networks, however, was greater than the average dispersal per generation. The data were also consistent with a genetic break between southern Oregon and central Oregon. We discuss whether additional nearshore RCAs in southern Oregon and Washington would help promote connectivity between RCA's for shallow-water rockfishes. PMID:24567745

  3. Not All Larvae Stay Close to Home: Insights into Marine Population Connectivity with a Focus on the Brown Surgeonfish (Acanthurus nigrofuscus)

    PubMed Central

    Eble, Jeff A.; Rocha, Luiz A.; Craig, Matthew T.; Bowen, Brian W.

    2014-01-01

    Recent reports of localized larval recruitment in predominately small-range fishes are countered by studies that show high genetic connectivity across large oceanic distances. This discrepancy may result from the different timescales over which genetic and demographic processes operate or rather may indicate regular long-distance dispersal in some species. Here, we contribute an analysis of mtDNA cytochrome b diversity in the widely distributed Brown Surgeonfish (Acanthurus nigrofuscus; N = 560), which revealed significant genetic structure only at the extremes of the range (ΦCT = 0.452; P < .001). Collections from Hawaii to the Eastern Indian Ocean comprise one large, undifferentiated population. This pattern of limited genetic subdivision across reefs of the central Indo-Pacific has been observed in a number of large-range reef fishes. Conversely, small-range fishes are often deeply structured over the same area. These findings demonstrate population connectivity differences among species at biogeographic and evolutionary timescales, which likely translates into differences in dispersal ability at ecological and demographic timescales. While interspecific differences in population connectivity complicate the design of management strategies, the integration of multiscale connectivity patterns into marine resource planning will help ensure long-term ecosystem stability by preserving functionally diverse communities. PMID:25505914

  4. One Fish, Two Fish, Redfish, You Fish!

    ERIC Educational Resources Information Center

    White, Katherine; Timmons, Maryellen; Medders, Paul

    2011-01-01

    The recreational fishing activity presented in this article provides a hands-on, problem-based experience for students; it unites biology, math, economics, environmental policy, and population dynamics concepts. In addition, the activity allows students to shape environmental policy in a realistic setting and evaluate their peers' work. By…

  5. Fishing Forecasts

    NASA Technical Reports Server (NTRS)

    1988-01-01

    ROFFS stands for Roffer's Ocean Fishing Forecasting Service, Inc. Roffer combines satellite and computer technology with oceanographic information from several sources to produce frequently updated charts sometimes as often as 30 times a day showing clues to the location of marlin, sailfish, tuna, swordfish and a variety of other types. Also provides customized forecasts for racing boats and the shipping industry along with seasonal forecasts that allow the marine industry to formulate fishing strategies based on foreknowledge of the arrival and departure times of different fish. Roffs service exemplifies the potential for benefits to marine industries from satellite observations. Most notable results are reduced search time and substantial fuel savings.

  6. Connectivity, biodiversity conservation and the design of marine reserve networks for coral reefs

    NASA Astrophysics Data System (ADS)

    Almany, G. R.; Connolly, S. R.; Heath, D. D.; Hogan, J. D.; Jones, G. P.; McCook, L. J.; Mills, M.; Pressey, R. L.; Williamson, D. H.

    2009-06-01

    Networks of no-take reserves are important for protecting coral reef biodiversity from climate change and other human impacts. Ensuring that reserve populations are connected to each other and non-reserve populations by larval dispersal allows for recovery from disturbance and is a key aspect of resilience. In general, connectivity between reserves should increase as the distance between them decreases. However, enhancing connectivity may often tradeoff against a network’s ability to representatively sample the system’s natural variability. This “representation” objective is typically measured in terms of species richness or diversity of habitats, but has other important elements (e.g., minimizing the risk that multiple reserves will be impacted by catastrophic events). Such representation objectives tend to be better achieved as reserves become more widely spaced. Thus, optimizing the location, size and spacing of reserves requires both an understanding of larval dispersal and explicit consideration of how well the network represents the broader system; indeed the lack of an integrated theory for optimizing tradeoffs between connectivity and representation objectives has inhibited the incorporation of connectivity into reserve selection algorithms. This article addresses these issues by (1) updating general recommendations for the location, size and spacing of reserves based on emerging data on larval dispersal in corals and reef fishes, and on considerations for maintaining genetic diversity; (2) using a spatial analysis of the Great Barrier Reef Marine Park to examine potential tradeoffs between connectivity and representation of biodiversity and (3) describing a framework for incorporating environmental fluctuations into the conceptualization of the tradeoff between connectivity and representation, and that expresses both in a common, demographically meaningful currency, thus making optimization possible.

  7. Fish Facts

    MedlinePlus

    ... not eat any fish because they worry about mercury in seafood. Mercury is a metal that, at high levels, can ... many types of seafood have little or no mercury at all. So your risk of mercury exposure ...

  8. Designer Fish.

    ERIC Educational Resources Information Center

    Hall, William R., Jr.

    1990-01-01

    Described is an activity in which students are asked to design a fish that would survive in a natural system. A project to computerize the activity is discussed. The development of this artificial intelligence software is detailed. (CW)

  9. Fish Allergy

    MedlinePlus

    ... specific fish used on the label. Read all product labels carefully before purchasing and consuming any item. Ingredients ... Getting Started Newly Diagnosed Emergency Care Plan Food Labels Mislabeled Products Tips for Managing Food Allergies Resources For... Most ...

  10. Is the Great Barracuda (Sphyraena barracuda) a reef fish or a pelagic fish? The phylogeographic perspective

    PubMed Central

    Randall, John E.; Bowen, Brian W.

    2013-01-01

    Current taxonomy indicates a single global species of the Great Barracuda (Sphyraena barracuda) despite differences in color and behavior between Atlantic and Pacific forms. To investigate these differences and qualify the dispersal characteristics of this unique coastal– pelagic teleost (bony fish), we conducted a global phylogeographic survey of 246 specimens from thirteen sampling locations using a 629-base pair fragment of mtDNA cytochrome b. Data indicate high overall gene flow in the Indo-Pacific over large distances (>16,500 km) bridging several biogeographic barriers. The West Atlantic population contains an mtDNA lineage that is divergent from the Indo-Pacific (d = 1.9%), while the East Atlantic (N = 23) has two mutations (d = 0.6%) apart from the Indo-Pacific. While we cannot rule out distinct evolutionary partitions among ocean basins based on behavior, coloration, and near-monophyly between Atlantic and Indo-Pacific subpopulations, more investigation is required before taxonomic status is revised. Overall, the pattern of high global dispersal and connectivity in S. barracuda more closely resembles those reported for large oceanic predators than reef-associated teleosts. PMID:25594680

  11. Connected Traveler

    SciTech Connect

    Schroeder, Alex

    2015-11-01

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing efficient traveler behavior. This poster outlines various aspects of the Connected Traveler project, including market opportunity, understanding traveler behavior and decision-making, automation and connectivity, and a projected timeline for Connected Traveler's key milestones.

  12. Representing connectivity: quantifying effective habitat availability based on area and connectivity for conservation status assessment and recovery

    PubMed Central

    Tumas, Hayley R.; Marsden, Brittany W.

    2014-01-01

    We apply a comprehensive suite of graph theoretic metrics to illustrate how landscape connectivity can be effectively incorporated into conservation status assessments and in setting conservation objectives. These metrics allow conservation practitioners to evaluate and quantify connectivity in terms of representation, resiliency, and redundancy and the approach can be applied in spite of incomplete knowledge of species-specific biology and dispersal processes. We demonstrate utility of the graph metrics by evaluating changes in distribution and connectivity that would result from implementing two conservation plans for three endangered plant species (Erigeron parishii, Acanthoscyphus parishii var. goodmaniana, and Eriogonum ovalifolium var. vineum) relative to connectivity under current conditions. Although distributions of the species differ from one another in terms of extent and specific location of occupied patches within the study landscape, the spatial scale of potential connectivity in existing networks were strikingly similar for Erigeron and Eriogonum, but differed for Acanthoscyphus. Specifically, patches of the first two species were more regularly distributed whereas subsets of patches of Acanthoscyphus were clustered into more isolated components. Reserves based on US Fish and Wildlife Service critical habitat designation would not greatly contribute to maintain connectivity; they include 83–91% of the extant occurrences and >92% of the aerial extent of each species. Effective connectivity remains within 10% of that in the whole network for all species. A Forest Service habitat management strategy excluded up to 40% of the occupied habitat of each species resulting in both range reductions and loss of occurrences from the central portions of each species’ distribution. Overall effective network connectivity was reduced to 62–74% of the full networks. The distance at which each CHMS network first became fully connected was reduced relative to the

  13. Representing connectivity: quantifying effective habitat availability based on area and connectivity for conservation status assessment and recovery.

    PubMed

    Neel, Maile; Tumas, Hayley R; Marsden, Brittany W

    2014-01-01

    We apply a comprehensive suite of graph theoretic metrics to illustrate how landscape connectivity can be effectively incorporated into conservation status assessments and in setting conservation objectives. These metrics allow conservation practitioners to evaluate and quantify connectivity in terms of representation, resiliency, and redundancy and the approach can be applied in spite of incomplete knowledge of species-specific biology and dispersal processes. We demonstrate utility of the graph metrics by evaluating changes in distribution and connectivity that would result from implementing two conservation plans for three endangered plant species (Erigeron parishii, Acanthoscyphus parishii var. goodmaniana, and Eriogonum ovalifolium var. vineum) relative to connectivity under current conditions. Although distributions of the species differ from one another in terms of extent and specific location of occupied patches within the study landscape, the spatial scale of potential connectivity in existing networks were strikingly similar for Erigeron and Eriogonum, but differed for Acanthoscyphus. Specifically, patches of the first two species were more regularly distributed whereas subsets of patches of Acanthoscyphus were clustered into more isolated components. Reserves based on US Fish and Wildlife Service critical habitat designation would not greatly contribute to maintain connectivity; they include 83-91% of the extant occurrences and >92% of the aerial extent of each species. Effective connectivity remains within 10% of that in the whole network for all species. A Forest Service habitat management strategy excluded up to 40% of the occupied habitat of each species resulting in both range reductions and loss of occurrences from the central portions of each species' distribution. Overall effective network connectivity was reduced to 62-74% of the full networks. The distance at which each CHMS network first became fully connected was reduced relative to the full

  14. Colloidal Dispersions

    NASA Astrophysics Data System (ADS)

    Russel, W. B.; Saville, D. A.; Schowalter, W. R.

    1992-03-01

    The book covers the physical side of colloid science from the individual forces acting between submicron particles suspended in a liquid through the resulting equilibrium and dynamic properties. The relevant forces include Brownian motion, electrostatic repulsion, dispersion attraction, both attraction and repulsion due to soluble polymer, and viscous forces due to relative motion between the particles and the liquid. The balance among Brownian motion and the interparticle forces decides the questions of stability and phase behavior. Imposition of external fields produces complex effects, i.e. electrokinetic phenomena (electric field), sedimentation (gravitational field), diffusion (concentration/chemical potential gradient), and non-Newtonian rheology (shear field). The treatment aims to impart a sound, quantitative understanding based on fundamental theory and experiments with well-characterized model systems. This broad grasp of the fundamentals lends insight and helps to develop the intuitive sense needed to isolate essential features of technological problems and design critical experiments. Some exposure to fluid mechanics, statistical mechanics, and electricity and magnetism is assumed, but each subject is reintroduced in a self-contained manner.

  15. Dispersion in alluvial convergent estuaries

    NASA Astrophysics Data System (ADS)

    Zhang, Zhilin; Savenije, Hubert H. G.

    2016-04-01

    The Van der Burgh's equation for longitudinal effective dispersion is a purely empirical method with practical implications. Its application to the effective tidal average dispersion under equilibrium conditions appears to have excellent performance in a wide range of alluvial estuaries. In this research, we try to find out the physical meaning of Van der Burgh's coefficient. Researchers like MacCready, Fischer, Kuijper, Hansen and Rattray have tried to split up dispersion into its constituents which did not do much to explain overall behaviour. In addition, traditional literature on dispersion is mostly related to flumes with constant cross-section. This research is about understanding the Van der Burgh's coefficient facing the fact that natural estuaries have exponentially varying cross-section. The objective is to derive a simple 1-D model considering both longitudinal and lateral mixing processes based on field observations (theoretical derivation). To that effect, we connect dispersion with salinity using the salt balance equation. Then we calculate the salinity along the longitudinal direction and compare it to the observed salinity. Calibrated dispersion coefficients in a range of estuaries are then compared with new expressions for the Van der Burgh's coefficient K and it is analysed if K varies from estuary to estuary. The set of reliable data used will be from estuaries: Kurau, Perak, Bernam, Selangor, Muar, Endau, Maputo, Thames, Corantijn, Sinnamary, Mae Klong, Lalang, Limpopo, Tha Chin, Chao Phraya, Edisto and Elbe.

  16. Spatial and Temporal Variability of Elemental Signautres in Juvenile Winter Flounder (Psuedopleuronectes americanus): Implications for Natal Connectivity

    EPA Science Inventory

    Elemental signatures in otoliths (fish ear-stones) have become a powerful tool in fisheries science for identifying fish migration patterns, reconstructing environmental histories, and for delineating the nursery origins of adult fish populations. Assessing connectivity between a...

  17. Temporal dynamics of a local fish community are strongly affected by immigration from the surrounding metacommunity

    PubMed Central

    Stoffels, Rick J; Clarke, Kenneth Robert; Linklater, Danielle S

    2015-01-01

    A 5-year time series of annual censuses was collected from a large floodplain lake to determine how dynamics of the local fish community were affected by changes in hydrological connectivity with the surrounding metacommunity. The lake was disconnected from the metacommunity for 1 year prior to our study and remained disconnected until 3 months before our third annual census, when a flood reconnected the lake to the metacommunity. We determined how changes in connectivity affected temporal dynamics of (1) local community composition and (2) the population composition, condition, and growth of catfish, to shed light on how immigration of other species might affect local population dynamics. Before reconnection, the community was likely shaped by interactions between the local environment and species traits. The reconnection caused significant immigration and change in community composition and correlated with a significant and abrupt decline in catfish condition, growth, and abundance; effects likely due to the immigration of a competitor with a similar trophic niche: carp. The community was slow to return to its preconnection state, which may be due to dispersal traits of the fishes, and a time-lag in the recovery of the local catfish population following transient intensification of species interactions. The dynamics observed were concordant with the species sorting and mass-effects perspectives of metacommunity theory. Floods cause episodic dispersal in floodplain fish metacommunities, and so, flood frequency determines the relative importance of regional and local processes. Local processes may be particularly important to certain species, but these species may need sufficient time between floods for population increase, before the next flood-induced dispersal episode brings competitors and predators that might cause population decline. Accordingly, species coexistence in these metacommunities may be facilitated by spatiotemporal storage effects, which may in

  18. Contrasting Genetic Structure among Populations of Two Amphidromous Fish Species (Sicydiinae) in the Central West Pacific

    PubMed Central

    Taillebois, Laura; Castelin, Magalie; Ovenden, Jennifer R.; Bonillo, Céline; Keith, Philippe

    2013-01-01

    Both present-day and past processes can shape connectivity of populations. Pleistocene vicariant events and dispersal have shaped the present distribution and connectivity patterns of aquatic species in the Indo-Pacific region. In particular, the processes that have shaped distribution of amphidromous goby species still remain unknown. Previous studies show that phylogeographic breaks are observed between populations in the Indian and Pacific Oceans where the shallow Sunda shelf constituted a geographical barrier to dispersal, or that the large spans of open ocean that isolate the Hawaiian or Polynesian Islands are also barriers for amphidromous species even though they have great dispersal capacity. Here we assess past and present genetic structure of populations of two amphidromous fish (gobies of the Sicydiinae) that are widely distributed in the Central West Pacific and which have similar pelagic larval durations. We analysed sections of mitochondrial COI, Cytb and nuclear Rhodospine genes in individuals sampled from different locations across their entire known range. Similar to other Sicydiinae fish, intraspecific mtDNA genetic diversity was high for all species (haplotype diversity between 0.9–0.96). Spatial analyses of genetic variation in Sicyopus zosterophorum demonstrated strong isolation across the Torres Strait, which was a geologically intermittent land barrier linking Australia to Papua New Guinea. There was a clear genetic break between the northwestern and the southwestern clusters in Si. zosterophorum (φST = 0.67502 for COI) and coalescent analyses revealed that the two populations split at 306 Kyr BP (95% HPD 79–625 Kyr BP), which is consistent with a Pleistocene separation caused by the Torres Strait barrier. However, this geographical barrier did not seem to affect Sm. fehlmanni. Historical and demographic hypotheses are raised to explain the different patterns of population structure and distribution between these species. Strategies

  19. Contrasting genetic structure among populations of two amphidromous fish species (Sicydiinae) in the Central West Pacific.

    PubMed

    Taillebois, Laura; Castelin, Magalie; Ovenden, Jennifer R; Bonillo, Céline; Keith, Philippe

    2013-01-01

    Both present-day and past processes can shape connectivity of populations. Pleistocene vicariant events and dispersal have shaped the present distribution and connectivity patterns of aquatic species in the Indo-Pacific region. In particular, the processes that have shaped distribution of amphidromous goby species still remain unknown. Previous studies show that phylogeographic breaks are observed between populations in the Indian and Pacific Oceans where the shallow Sunda shelf constituted a geographical barrier to dispersal, or that the large spans of open ocean that isolate the Hawaiian or Polynesian Islands are also barriers for amphidromous species even though they have great dispersal capacity. Here we assess past and present genetic structure of populations of two amphidromous fish (gobies of the Sicydiinae) that are widely distributed in the Central West Pacific and which have similar pelagic larval durations. We analysed sections of mitochondrial COI, Cytb and nuclear Rhodospine genes in individuals sampled from different locations across their entire known range. Similar to other Sicydiinae fish, intraspecific mtDNA genetic diversity was high for all species (haplotype diversity between 0.9-0.96). Spatial analyses of genetic variation in Sicyopus zosterophorum demonstrated strong isolation across the Torres Strait, which was a geologically intermittent land barrier linking Australia to Papua New Guinea. There was a clear genetic break between the northwestern and the southwestern clusters in Si. zosterophorum (φST = 0.67502 for COI) and coalescent analyses revealed that the two populations split at 306 Kyr BP (95% HPD 79-625 Kyr BP), which is consistent with a Pleistocene separation caused by the Torres Strait barrier. However, this geographical barrier did not seem to affect Sm. fehlmanni. Historical and demographic hypotheses are raised to explain the different patterns of population structure and distribution between these species. Strategies

  20. Monitoring fish distributions along electrofishing segments

    USGS Publications Warehouse

    Miranda, Leandro E.

    2014-01-01

    Electrofishing is widely used to monitor fish species composition and relative abundance in streams and lakes. According to standard protocols, multiple segments are selected in a body of water to monitor population relative abundance as the ratio of total catch to total sampling effort. The standard protocol provides an assessment of fish distribution at a macrohabitat scale among segments, but not within segments. An ancillary protocol was developed for assessing fish distribution at a finer scale within electrofishing segments. The ancillary protocol was used to estimate spacing, dispersion, and association of two species along shore segments in two local reservoirs. The added information provided by the ancillary protocol may be useful for assessing fish distribution relative to fish of the same species, to fish of different species, and to environmental or habitat characteristics.

  1. Commercial Fishing.

    ERIC Educational Resources Information Center

    Florida State Dept. of Education, Tallahassee. Div. of Vocational Education.

    This document is a curriculum framework for a program in commercial fishing to be taught in Florida secondary and postsecondary institutions. This outline covers the major concepts/content of the program, which is designed to prepare students for employment in occupations with titles such as net fishers, pot fishers, line fishers, shrimp boat…

  2. Gone Fishing.

    ERIC Educational Resources Information Center

    Olson-Demme, Hillary; Kisiel, Jim

    2003-01-01

    Presents a hands-on activity in which students create a model of an ocean ecosystem to gain an understanding of how humans can alter biodiversity through their actions. Uses differing levels of fishing technology to explore the concepts of sustainability and overfishing. (Author/SOE)

  3. Connectivity across the Caribbean Sea: DNA barcoding and morphology unite an enigmatic fish larva from the Florida straits with a new species of sea bass from deep reefs off Curaçao.

    PubMed

    Baldwin, Carole C; Johnson, G David

    2014-01-01

    Integrative taxonomy, in which multiple disciplines are combined to address questions related to biological species diversity, is a valuable tool for identifying pelagic marine fish larvae and recognizing the existence of new fish species. Here we combine data from DNA barcoding, comparative morphology, and analysis of color patterns to identify an unusual fish larva from the Florida Straits and demonstrate that it is the pelagic larval phase of a previously undescribed species of Liopropoma sea bass from deep reefs off Curaçao, southern Caribbean. The larva is unique among larvae of the teleost family Serranidae, Tribe Liopropomini, in having seven elongate dorsal-fin spines. Adults of the new species are similar to the golden bass, Liopropoma aberrans, with which they have been confused, but they are distinct genetically and morphologically. The new species differs from all other western Atlantic liopropomins in having IX, 11 dorsal-fin rays and in having a unique color pattern-most notably the predominance of yellow pigment on the dorsal portion of the trunk, a pale to white body ventrally, and yellow spots scattered across both the dorsal and ventral portions of the trunk. Exploration of deep reefs to 300 m using a manned submersible off Curaçao is resulting in the discovery of numerous new fish species, improving our genetic databases, and greatly enhancing our understanding of deep-reef fish diversity in the southern Caribbean. Oh the mother and child reunion is only a moment away. Paul Simon. PMID:24825118

  4. Connectivity across the Caribbean Sea: DNA Barcoding and Morphology Unite an Enigmatic Fish Larva from the Florida Straits with a New Species of Sea Bass from Deep Reefs off Curaçao

    PubMed Central

    Baldwin, Carole C.; Johnson, G. David

    2014-01-01

    Integrative taxonomy, in which multiple disciplines are combined to address questions related to biological species diversity, is a valuable tool for identifying pelagic marine fish larvae and recognizing the existence of new fish species. Here we combine data from DNA barcoding, comparative morphology, and analysis of color patterns to identify an unusual fish larva from the Florida Straits and demonstrate that it is the pelagic larval phase of a previously undescribed species of Liopropoma sea bass from deep reefs off Curaçao, southern Caribbean. The larva is unique among larvae of the teleost family Serranidae, Tribe Liopropomini, in having seven elongate dorsal-fin spines. Adults of the new species are similar to the golden bass, Liopropoma aberrans, with which they have been confused, but they are distinct genetically and morphologically. The new species differs from all other western Atlantic liopropomins in having IX, 11 dorsal-fin rays and in having a unique color pattern–most notably the predominance of yellow pigment on the dorsal portion of the trunk, a pale to white body ventrally, and yellow spots scattered across both the dorsal and ventral portions of the trunk. Exploration of deep reefs to 300 m using a manned submersible off Curaçao is resulting in the discovery of numerous new fish species, improving our genetic databases, and greatly enhancing our understanding of deep-reef fish diversity in the southern Caribbean. Oh the mother and child reunion is only a moment away. Paul Simon. PMID:24825118

  5. Spatial and temporal influences on hydrologic connectivity: A mathematical formalization

    EPA Science Inventory

    Connectivity between landscape elements has been an important consideration in landscape ecology since at least the mid-1980s. In particular, the use of random landscapes to study the interaction between connectivity, landscape structure, and dispersal mechanisms has provided in...

  6. Ocean acidification alters the otoliths of a pantropical fish species with implications for sensory function

    PubMed Central

    Bignami, Sean; Enochs, Ian C.; Manzello, Derek P.; Sponaugle, Su; Cowen, Robert K.

    2013-01-01

    Ocean acidification affects a wide diversity of marine organisms and is of particular concern for vulnerable larval stages critical to population replenishment and connectivity. Whereas it is well known that ocean acidification will negatively affect a range of calcareous taxa, the study of fishes is more limited in both depth of understanding and diversity of study species. We used new 3D microcomputed tomography to conduct in situ analysis of the impact of ocean acidification on otolith (ear stone) size and density of larval cobia (Rachycentron canadum), a large, economically important, pantropical fish species that shares many life history traits with a diversity of high-value, tropical pelagic fishes. We show that 2,100 μatm partial pressure of carbon dioxide (pCO2) significantly increased not only otolith size (up to 49% greater volume and 58% greater relative mass) but also otolith density (6% higher). Estimated relative mass in 800 μatm pCO2 treatments was 14% greater, and there was a similar but nonsignificant trend for otolith size. Using a modeling approach, we demonstrate that these changes could affect auditory sensitivity including a ∼50% increase in hearing range at 2,100 μatm pCO2, which may alter the perception of auditory information by larval cobia in a high-CO2 ocean. Our results indicate that ocean acidification has a graded effect on cobia otoliths, with the potential to substantially influence the dispersal, survival, and recruitment of a pelagic fish species. These results have important implications for population maintenance/replenishment, connectivity, and conservation efforts for other valuable fish stocks that are already being deleteriously impacted by overfishing. PMID:23589887

  7. Ocean acidification alters the otoliths of a pantropical fish species with implications for sensory function.

    PubMed

    Bignami, Sean; Enochs, Ian C; Manzello, Derek P; Sponaugle, Su; Cowen, Robert K

    2013-04-30

    Ocean acidification affects a wide diversity of marine organisms and is of particular concern for vulnerable larval stages critical to population replenishment and connectivity. Whereas it is well known that ocean acidification will negatively affect a range of calcareous taxa, the study of fishes is more limited in both depth of understanding and diversity of study species. We used new 3D microcomputed tomography to conduct in situ analysis of the impact of ocean acidification on otolith (ear stone) size and density of larval cobia (Rachycentron canadum), a large, economically important, pantropical fish species that shares many life history traits with a diversity of high-value, tropical pelagic fishes. We show that 2,100 μatm partial pressure of carbon dioxide (pCO2) significantly increased not only otolith size (up to 49% greater volume and 58% greater relative mass) but also otolith density (6% higher). Estimated relative mass in 800 μatm pCO2 treatments was 14% greater, and there was a similar but nonsignificant trend for otolith size. Using a modeling approach, we demonstrate that these changes could affect auditory sensitivity including a ∼50% increase in hearing range at 2,100 μatm pCO2, which may alter the perception of auditory information by larval cobia in a high-CO2 ocean. Our results indicate that ocean acidification has a graded effect on cobia otoliths, with the potential to substantially influence the dispersal, survival, and recruitment of a pelagic fish species. These results have important implications for population maintenance/replenishment, connectivity, and conservation efforts for other valuable fish stocks that are already being deleteriously impacted by overfishing. PMID:23589887

  8. Modelling Infectious Hematopoietic Necrosis Virus Dispersion from Marine Salmon Farms in the Discovery Islands, British Columbia, Canada.

    PubMed

    Foreman, Michael G G; Guo, Ming; Garver, Kyle A; Stucchi, Dario; Chandler, Peter; Wan, Di; Morrison, John; Tuele, Darren

    2015-01-01

    Finite volume ocean circulation and particle tracking models are used to simulate water-borne transmission of infectious hematopoietic necrosis virus (IHNV) among Atlantic salmon (Salmo salar) farms in the Discovery Islands region of British Columbia, Canada. Historical simulations for April and July 2010 are carried out to demonstrate the seasonal impact of river discharge, wind, ultra-violet (UV) radiation, and heat flux conditions on near-surface currents, viral dispersion and survival. Numerical particles released from infected farm fish in accordance with IHNV shedding rates estimated through laboratory experiments are dispersed by model oceanic flows. Viral particles are inactivated by ambient UV radiation levels and by the natural microbial community at rates derived through laboratory studies. Viral concentration maps showing temporal and spatial changes are produced and combined with lab-determined minimum infectious dosages to estimate the infective connectivity among farms. Results demonstrate that neighbouring naïve farms can become exposed to IHNV via water-borne transport from an IHNV diseased farm, with a higher risk in April than July, and that many events in the sequence of farm outbreaks in 2001-2002 are consistent with higher risks in our farm connectivity matrix. Applications to other diseases, transfers between farmed and wild fish, and the effect of vaccinations are also discussed. PMID:26114643

  9. Modelling Infectious Hematopoietic Necrosis Virus Dispersion from Marine Salmon Farms in the Discovery Islands, British Columbia, Canada

    PubMed Central

    Foreman, Michael G. G.; Guo, Ming; Garver, Kyle A.; Stucchi, Dario; Chandler, Peter; Wan, Di; Morrison, John; Tuele, Darren

    2015-01-01

    Finite volume ocean circulation and particle tracking models are used to simulate water-borne transmission of infectious hematopoietic necrosis virus (IHNV) among Atlantic salmon (Salmo salar) farms in the Discovery Islands region of British Columbia, Canada. Historical simulations for April and July 2010 are carried out to demonstrate the seasonal impact of river discharge, wind, ultra-violet (UV) radiation, and heat flux conditions on near-surface currents, viral dispersion and survival. Numerical particles released from infected farm fish in accordance with IHNV shedding rates estimated through laboratory experiments are dispersed by model oceanic flows. Viral particles are inactivated by ambient UV radiation levels and by the natural microbial community at rates derived through laboratory studies. Viral concentration maps showing temporal and spatial changes are produced and combined with lab-determined minimum infectious dosages to estimate the infective connectivity among farms. Results demonstrate that neighbouring naïve farms can become exposed to IHNV via water-borne transport from an IHNV diseased farm, with a higher risk in April than July, and that many events in the sequence of farm outbreaks in 2001-2002 are consistent with higher risks in our farm connectivity matrix. Applications to other diseases, transfers between farmed and wild fish, and the effect of vaccinations are also discussed. PMID:26114643

  10. Dispersal of the radionuclide caesium-137 ((137)Cs) from point sources in the Barents and Norwegian Seas and its potential contamination of the Arctic marine food chain: coupling numerical ocean models with geographical fish distribution data.

    PubMed

    Heldal, Hilde Elise; Vikebø, Frode; Johansen, Geir Odd

    2013-09-01

    Dispersal of (137)Cs from the nuclear submarine wrecks Komsomolets and K-159, which are resting on the seabed in the Norwegian and Barents Seas, respectively, is simulated using realistic rates and hypothetical scenarios. Furthermore, spatiotemporal (137)Cs concentrations in Northeast Arctic cod and capelin are estimated based on survey data. The results indicate that neither continuous leakages nor pulse discharges will cause concentrations of (137)Cs in cod muscle or whole body capelin exceeding the intervention level of 600 Bq/kg fw. Continuous leakages from Komsomolets and K-159 and pulse discharges from Komsomolets induced negligible activity concentrations in cod and capelin. A pulse discharge of 100% of the (137)Cs-inventory of K-159 will, however, result in concentrations in muscle of cod of above 100 times the present levels in the eastern Barents Sea. Within three years after the release, (137)Cs levels above 20 Bq/kg fw in cod are no longer occurring in the Barents Sea. PMID:23771062

  11. Dispersal of the radionuclide caesium-137 (137Cs) from point sources in the Barents and Norwegian Seas and its potential contamination of the Arctic marine food chain: coupling numerical ocean models with geographical fish distribution data.

    PubMed

    Heldal, Hilde Elise; Vikebø, Frode; Johansen, Geir Odd

    2012-05-01

    Dispersal of (137)Cs from Komsomolets and K-159 is simulated using realistic rates and hypothetical scenarios. Furthermore, spatiotemporal (137)Cs concentrations in Northeast Arctic cod and capelin are estimated based on survey data. The results indicate that only pulse discharges from K-159 will cause concentrations of (137)Cs in cod muscle exceeding the intervention level of 600 Bq/kg fresh weight. A discharge of ≥10% of the (137)Cs-inventory will result in concentrations in muscle of cod exceeding the intervention level for approximately two years. In fact, a discharge of 10% of the (137)Cs-inventory results in an overlap of 8-30% between the different size groups of cod and levels that exceed the intervention level during the first year after the discharge. For capelin, individuals less than one year old during the first year after a discharge are more likely to be severely affected by discharges comprising ≥50% of the inventory. PMID:22306959

  12. Monitoring the contents of six steroidal and phenolic endocrine disrupting chemicals in chicken, fish and aquaculture pond water samples using pre-column derivatization and dispersive liquid-liquid microextraction with the aid of experimental design methodology.

    PubMed

    Wu, Hongliang; Li, Guoliang; Liu, Shucheng; Hu, Na; Geng, Dandan; Chen, Guang; Sun, Zhiwei; Zhao, Xianen; Xia, Lian; You, Jinmao

    2016-02-01

    This research established a sensitive and efficient pre-column derivatization HPLC method based on dispersive liquid-liquid microextraction (DLLME) for the simultaneous determination of six steroidal and phenolic endocrine disrupting chemicals (EDCs). In this study, EDCs were firstly labeled by the derivatization reagent 2-(11H-benzo[a]carbazol-11-yl) ethyl carbonochloridate (BCEC-Cl) and then extracted by DLLME. The response surface methodology was employed to investigate the key parameters of pre-column derivatization and DLLME. Under the optimal conditions, a good linear relationship between the peak area and the concentration of analytes was observed with correlation coefficients of >0.9991. Limits of detection for all EDCs derivatives were achieved within the range of 0.02-0.07 μg L(-1). The proposed method has the advantages of simple operation, low consumption of organic solvent, saving time, low output limit and good selectivity. When applied to several food and water samples analysis, it demonstrated good applicability for the determination of EDCs. PMID:26304325

  13. Prevention of zebra mussel infestation and dispersal during aquaculture operations

    USGS Publications Warehouse

    Waller, D.L.; Fisher, S.W.; Dabrowska, H.

    1996-01-01

    The zebra mussel Dreissena polymorpha, an exotic invasive species, poses a major threat to North American fish management programs and the aquaculture industry. Fish hatcheries may become infected with zebra mussels from a variety of sources, including the water supply, fish shipments, boats, and equipment. The hatcheries could then serve as agents for the overland dispersal of zebra mussels into stocked waters and to other fish hatcheries. We evaluated the effectiveness and safety of aquaculture chemicals for use in controlling zebra mussels in fish hatcheries and preventing dispersal of veligers during fish transport. Chemicals were evaluated for use in fish transport and as disinfectants for ponds and equipment. Standardized static toxicity tests were conducted with representative species of warmwater, coolwater, and coldwater fishes and with larval (3-d-old veligers), early juvenile (settling larvae), and adult zebra mussels. Chemical concentrations and exposure durations were based on recommended treatment levels for fish, eggs, and ponds. Recommended treatment levels were also exceeded, if necessary, to establish lethal levels for zebra mussels of different developmental stages. Our results indicate that some chemicals currently in use in hatcheries may be effective for controlling zebra mussels in various operations. Chloride salts were the safest and most effective therapeutants tested for use in fish transport. The toxicity of chloride salts to fish varied among species and with temperature; only one treatment regime (sodium chloride at 10,000 mg/L) was safe to all fish species that we tested, but it was only effective on veliger and settler stages of the zebra mussel. Effective disinfectants were benzalkonium chloride for use on equipment and rotenone for use in ponds after fish are harvested. The regulatory status of the identified chemicals is discussed as well as several nonchemical control alternatives.

  14. Oceanography and life history predict contrasting genetic population structure in two Antarctic fish species.

    PubMed

    Young, Emma F; Belchier, Mark; Hauser, Lorenz; Horsburgh, Gavin J; Meredith, Michael P; Murphy, Eugene J; Pascoal, Sonia; Rock, Jennifer; Tysklind, Niklas; Carvalho, Gary R

    2015-06-01

    Understanding the key drivers of population connectivity in the marine environment is essential for the effective management of natural resources. Although several different approaches to evaluating connectivity have been used, they are rarely integrated quantitatively. Here, we use a 'seascape genetics' approach, by combining oceanographic modelling and microsatellite analyses, to understand the dominant influences on the population genetic structure of two Antarctic fishes with contrasting life histories, Champsocephalus gunnari and Notothenia rossii. The close accord between the model projections and empirical genetic structure demonstrated that passive dispersal during the planktonic early life stages is the dominant influence on patterns and extent of genetic structuring in both species. The shorter planktonic phase of C. gunnari restricts direct transport of larvae between distant populations, leading to stronger regional differentiation. By contrast, geographic distance did not affect differentiation in N. rossii, whose longer larval period promotes long-distance dispersal. Interannual variability in oceanographic flows strongly influenced the projected genetic structure, suggesting that shifts in circulation patterns due to climate change are likely to impact future genetic connectivity and opportunities for local adaptation, resilience and recovery from perturbations. Further development of realistic climate models is required to fully assess such potential impacts. PMID:26029262

  15. Oceanography and life history predict contrasting genetic population structure in two Antarctic fish species

    PubMed Central

    Young, Emma F; Belchier, Mark; Hauser, Lorenz; Horsburgh, Gavin J; Meredith, Michael P; Murphy, Eugene J; Pascoal, Sonia; Rock, Jennifer; Tysklind, Niklas; Carvalho, Gary R

    2015-01-01

    Understanding the key drivers of population connectivity in the marine environment is essential for the effective management of natural resources. Although several different approaches to evaluating connectivity have been used, they are rarely integrated quantitatively. Here, we use a ‘seascape genetics’ approach, by combining oceanographic modelling and microsatellite analyses, to understand the dominant influences on the population genetic structure of two Antarctic fishes with contrasting life histories, Champsocephalus gunnari and Notothenia rossii. The close accord between the model projections and empirical genetic structure demonstrated that passive dispersal during the planktonic early life stages is the dominant influence on patterns and extent of genetic structuring in both species. The shorter planktonic phase of C. gunnari restricts direct transport of larvae between distant populations, leading to stronger regional differentiation. By contrast, geographic distance did not affect differentiation in N. rossii, whose longer larval period promotes long-distance dispersal. Interannual variability in oceanographic flows strongly influenced the projected genetic structure, suggesting that shifts in circulation patterns due to climate change are likely to impact future genetic connectivity and opportunities for local adaptation, resilience and recovery from perturbations. Further development of realistic climate models is required to fully assess such potential impacts. PMID:26029262

  16. Making Connections

    ERIC Educational Resources Information Center

    Turner, Paul

    2015-01-01

    This article aims to illustrate a process of making connections, not between mathematics and other activities, but within mathematics itself--between diverse parts of the subject. Novel connections are still possible in previously explored mathematics when the material happens to be unfamiliar, as may be the case for a learner at any career stage.…

  17. Hydrokinetic turbine effects on fish swimming behaviour.

    PubMed

    Hammar, Linus; Andersson, Sandra; Eggertsen, Linda; Haglund, Johan; Gullström, Martin; Ehnberg, Jimmy; Molander, Sverker

    2013-01-01

    Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their movements through the area when the rotor was present. This deterrent effect on fish increased with current speed. Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish were particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms(-1). The effects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shape influenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during the investigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fish movements, particularly for large species, with possible effects on habitat connectivity if migration routes are exploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps of several metres width to allow large fish to pass through. In combination with further research the insights from this study can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecological impacts. PMID:24358334

  18. Hydrokinetic Turbine Effects on Fish Swimming Behaviour

    PubMed Central

    Hammar, Linus; Andersson, Sandra; Eggertsen, Linda; Haglund, Johan; Gullström, Martin; Ehnberg, Jimmy; Molander, Sverker

    2013-01-01

    Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their movements through the area when the rotor was present. This deterrent effect on fish increased with current speed. Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish were particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms-1. The effects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shape influenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during the investigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fish movements, particularly for large species, with possible effects on habitat connectivity if migration routes are exploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps of several metres width to allow large fish to pass through. In combination with further research the insights from this study can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecological impacts. PMID:24358334

  19. Fish Tales

    SciTech Connect

    McLerran, L.

    2010-07-06

    This talk is about fishing and the friendships that have resulted in its pursuit. It is also about theoretical physics, and the relationship of imagination and fantasy to the establishment of ideas about nature. Fishermen, like theoretical physicists, are well known for their inventive imaginations. Perhaps neither are as clever as sailors, who conceived of the mermaid. If one doubts the power of this fantasy, one should remember the ghosts of the many sailors who drowned pursuing these young nymphs. An extraordinary painting by J. Waterhouse is shown as Fig. 1. The enchantment of a mermaid must reflect an extraordinary excess of imagination on the part of the sailor, perhaps together with an impractical turn of mind. A consummated relationship with a mermaid is after all, by its very nature a fantasy incapable of realization. To a theoretical physicist, she is symbolic of many ideas we develop. There are many truths known to fisherman in which one might also find parallels to the goals of scientists: (1) A fish is the only animal that keeps growing after its death; (2) Nothing makes a fish bigger than almost being caught; (3) ''...of all the liars among mankind, the fisherman is the most trustworthy.'' (William Sherwood Fox, in Silken Lines and Silver Hooks); and (4) Men and fish are alike. They both get into trouble when they open their mouths. These quotes may be interpreted as reflecting skepticism regarding the honesty of fisherman, and probably do not reflect adequate admiration for a creative imagination. Is it fair to criticize a person for believing a falsehood that he or she sincerely believes to be true? The fisherman simultaneously invents the lie, and believes in it himself. The parallel with theoretical physics is perhaps only approximate, although we physicists may invent stories that we come to believe, on some rare occasions our ideas actually correspond to a more or less true descriptions of nature. These minor philosophical differences are not

  20. Frugivory by the fish Brycon hilarii (Characidae) in western Brazil

    NASA Astrophysics Data System (ADS)

    Reys, Paula; Sabino, José; Galetti, Mauro

    2009-01-01

    Frugivory and seed dispersal have been poorly studied in Neotropical freshwater fishes. We studied frugivory and seed dispersal by the piraputanga fish ( Brycon hilarii, Characidae) in the Formoso River, Bonito, western Brazil. We examined the stomach contents of 87 fish and found the diet of piraputanga consisted of 24% animal prey (arthropods, snails, and vertebrates), 31% seeds/fruits and 45% other plant material (algae/macrophytes/leaves/flowers). The piraputangas fed on 12 fruit species, and were considered as seed dispersers of eight species. Fruits with soft seeds larger than 10 mm were triturated, but all species with small seeds (e.g. Ficus, Psidium) and one species with large hard seed ( Chrysophyllum gonocarpum) were dispersed. Piraputangas eat more fruits in the dry season just before the migration, but not during the spawning season. Fish length had a positive relation with the presence of fruits in their guts. The gallery forest of the Formoso River apparently does not have any plant species that depend exclusively on B. hilarii for seed dispersal because all fruit species are also dispersed by birds and mammals. Based on seed size and husk hardness of the riparian plant community of Formoso River, however, the piraputangas may potentially disperse at least 50% of the riparian fleshy fruit species and may be particularly important for long-distance dispersal. Therefore, overfishing or other anthropogenic disturbances to the populations of piraputanga may have negative consequences for the riparian forests in this region.

  1. Cross-Cordillera exchange mediated by the Panama Canal increased the species richness of local freshwater fish assemblages.

    PubMed

    Smith, Scott A; Bell, Graham; Bermingham, Eldredge

    2004-09-22

    Completion of the Panama Canal in 1914 breached the continental divide and set into motion a natural experiment of unprecedented magnitude by bringing previously isolated freshwater fish communities into contact. The construction of a freshwater corridor connecting evolutionarily isolated communities in Pacific and Caribbean watersheds dramatically increased the rate of dispersal, without directly affecting species interactions. Here, we report that a large fraction of species have been able to establish themselves on the other side of the continental divide, whereas no species have become extinct, leading to a local increase in species richness. Our results suggest that communities are not saturated and that competitive exclusion does not occur over the time-scale previously envisioned. Moreover, the results of this unintentional experiment demonstrate that community composition and species richness were regulated by the regional process of dispersal, rather than by local processes such as competition and predation. PMID:15347510

  2. Invasion Dynamics of a Fish-Free Landscape by Brown Trout (Salmo trutta)

    PubMed Central

    Labonne, Jacques; Vignon, Matthias; Prévost, Etienne; Lecomte, Frédéric; Dodson, Julian J.; Kaeuffer, Renaud; Aymes, Jean-Christophe; Jarry, Marc; Gaudin, Philippe; Davaine, Patrick; Beall, Edward

    2013-01-01

    Metapopulation dynamics over the course of an invasion are usually difficult to grasp because they require large and reliable data collection, often unavailable. The invasion of the fish-free freshwater ecosystems of the remote sub-Antarctic Kerguelen Islands following man-made introductions of brown trout (Salmo trutta) in the 1950's is an exception to this rule. Benefiting from a full long term environmental research monitoring of the invasion, we built a Bayesian dynamic metapopulation model to analyze the invasion dynamics of 85 river systems over 51 years. The model accounted for patch size (river length and connections to lakes), alternative dispersal pathways between rivers, temporal trends in dynamics, and uncertainty in colonization date. The results show that the model correctly represents the observed pattern of invasion, especially if we assume a coastal dispersal pathway between patches. Landscape attributes such as patch size influenced the colonization function, but had no effect on propagule pressure. Independently from patch size and distance between patches, propagule pressure and colonization function were not constant through time. Propagule pressure increased over the course of colonization, whereas the colonization function decreased, conditional on propagule pressure. The resulting pattern of this antagonistic interplay is an initial rapid invasion phase followed by a strong decrease in the invasion rate. These temporal trends may be due to either adaptive processes or environmental gradients encountered along the colonization front. It was not possible to distinguish these two hypotheses. Because invasibility of Kerguelen Is. freshwater ecosystems is very high due to the lack of a pre-existing fish fauna and minimal human interference, our estimates of invasion dynamics represent a blueprint for the potential of brown trout invasiveness in pristine environments. Our conclusions shed light on the future of polar regions where, because of

  3. About connections.

    PubMed

    Rockland, Kathleen S

    2015-01-01

    Despite the attention attracted by "connectomics", one can lose sight of the very real questions concerning "What are connections?" In the neuroimaging community, "structural" connectivity is ground truth and underlying constraint on "functional" or "effective" connectivity. It is referenced to underlying anatomy; but, as increasingly remarked, there is a large gap between the wealth of human brain mapping and the relatively scant data on actual anatomical connectivity. Moreover, connections have typically been discussed as "pairwise", point x projecting to point y (or: to points y and z), or more recently, in graph theoretical terms, as "nodes" or regions and the interconnecting "edges". This is a convenient shorthand, but tends not to capture the richness and nuance of basic anatomical properties as identified in the classic tradition of tracer studies. The present short review accordingly revisits connectional weights, heterogeneity, reciprocity, topography, and hierarchical organization, drawing on concrete examples. The emphasis is on presynaptic long-distance connections, motivated by the intention to probe current assumptions and promote discussions about further progress and synthesis. PMID:26042001

  4. On the mathematics underlying dispersion relations

    NASA Astrophysics Data System (ADS)

    Labuda, Cecille; Labuda, Iwo

    2014-12-01

    The history of mathematical methods underlying the study of dispersion relations in physics is discussed. In particular, some misconceptions connected with a theorem known in the physics literature as Titchmarsh's Theorem are addressed. It is pointed out that the aforementioned theorem is a compilation of two well-known theorems in mathematics, the Paley-Wiener theorem and the Marcel Riesz theorem.

  5. Can Species Traits Predict the Susceptibility of Riverine Fish to Water Resource Development? An Australian Case Study

    NASA Astrophysics Data System (ADS)

    Rolls, Robert J.; Sternberg, David

    2015-06-01

    Water resource developments alter riverine environments by disrupting longitudinal connectivity, transforming lotic habitats, and modifying in-stream hydraulic conditions. Effective management of anthropogenic disturbances therefore requires an understanding of the range of potential ecosystem effects and the inherent traits symptomatic of elevated vulnerability to disturbance. Using 42 riverine fish native to South Eastern Australia as a case study, we quantified six morphological, behavioral, and life-history traits to classify species into groups reflecting potential differences in their response to ecosystem changes as a result of water resource development. Classification analysis identified five strategies based on fish life-history dispersal requirements, climbing potential, and habitat preference. These strategies in turn highlight the potential species at risk from the separate impacts of water resource development and inform management decisions to mitigate those risks. Swimming ability did not contribute to distinguishing species into functional groups, likely due to methodological inconsistencies in quantifying swimming performance that may ultimately hinder the ability of fish passage facilities to function within the physical capabilities of species at risk of habitat fragmentation. This study improves our ability to predict the performance of groups of species at risk from the multiple environmental changes imposed by humans and goes beyond broad-scale dispersal requirements as a predictor of individual species response.

  6. Statistical dispersion relation for spatially broadband fields.

    PubMed

    Shan, Mingguang; Nastasa, Viorel; Popescu, Gabriel

    2016-06-01

    The dispersion relation is fundamental to a physical phenomenon that develops in both space and time. This equation connects the spatial and temporal frequencies involved in the dynamic process through the material constants. Electromagnetic plane waves propagating in homogeneous media are bound by simple dispersion relation, which sets the magnitude of the spatial frequency, k, as being proportional to the temporal frequency, ω, with the proportionality constant dependent on the refractive index, n, and the speed of light in vacuum, c. Here we show that, for spatially broadband fields, an analog dispersion relation can be derived, except in this case the k-vector variance is connected with the temporal frequency through the statistics of the refractive index fluctuations in the medium. We discuss how this relationship can be used to retrieve information about refractive index distributions in biological tissues. This result is particularly significant in measurements of angular light scattering and quantitative phase imaging of biological structures. PMID:27244396

  7. Fishing amplifies forage fish population collapses

    PubMed Central

    Essington, Timothy E.; Moriarty, Pamela E.; Froehlich, Halley E.; Hodgson, Emma E.; Koehn, Laura E.; Oken, Kiva L.; Siple, Margaret C.; Stawitz, Christine C.

    2015-01-01

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches. PMID:25848018

  8. Fishing amplifies forage fish population collapses.

    PubMed

    Essington, Timothy E; Moriarty, Pamela E; Froehlich, Halley E; Hodgson, Emma E; Koehn, Laura E; Oken, Kiva L; Siple, Margaret C; Stawitz, Christine C

    2015-05-26

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches. PMID:25848018

  9. Lectures on Dispersion Theory

    DOE R&D Accomplishments Database

    Salam, A.

    1956-04-01

    Lectures with mathematical analysis are given on Dispersion Theory and Causality and Dispersion Relations for Pion-nucleon Scattering. The appendix includes the S-matrix in terms of Heisenberg Operators. (F. S.)

  10. Fish tapeworm infection

    MedlinePlus

    Fish tapeworm infection is an intestinal infection with the tapeworm parasite found in fish. ... The fish tapeworm ( Diphyllobothrium latum ) is the largest parasite that infects humans. Humans become infected when they eat raw ...

  11. Got a Sick Fish?

    MedlinePlus

    ... Welfare Veterinary Careers Public Health Got a sick fish? Fish with disease can show a variety of signs. If you notice your pet fish having any unusual disease signs, contact your veterinarian ...

  12. Microencapsulation of Fish Oil

    NASA Astrophysics Data System (ADS)

    Beindorff, Christiaan M.; Zuidam, Nicolaas Jan

    For those fortunate to live near rivers, lakes and the sea, fish has been part of their diet for many centuries, and trade in dried fish has a long history. The important fishing industry developed when fishermen started to fish over wider areas of the seas and when improvements in freezing facilities allowed storage at sea, and subsequent distribution to urban consumers. For many, fresh fish and fried fish are now a part of their standard diet.

  13. Dispersion y dinamica poblacional

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dispersal behavior of fruit flies is appetitive. Measures of dispersion involve two different parameter: the maximum distance and the standard distance. Standard distance is a parameter that describes the probalility of dispersion and is mathematically equivalent to the standard deviation around ...

  14. Fish mycobacteriosis (Tuberculosis)

    USGS Publications Warehouse

    Parisot, T.J.; Wood, J.W.

    1959-01-01

    The etiologic agent for the bacterial disease, "fish tuberculosis" (more correctly "mycobacteriosis"), was first observed in carp in 189& from a pond in France. Subsequently similar agents have been isolated from or observed in fish in fresh water, salt water, and brackish water, in fish in aquaria, hatcheries, and natural habitat~ (wild populations of fish). The disease has been recognized as an important infection among hatchery reared salmonid fishes on the West Coast of the United States, and in aquarium fishes such as the neon tetra, the Siamese fighting fish, and in salt water fish held in zoological displays.

  15. Pelagic larval duration and settlement size of a reef fish are spatially consistent, but post-settlement growth varies at the reef scale

    NASA Astrophysics Data System (ADS)

    Leahy, Susannah M.; Russ, Garry R.; Abesamis, Rene A.

    2015-12-01

    Recent research has demonstrated that, despite a pelagic larval stage, many coral reef fishes disperse over relatively small distances, leading to well-connected populations on scales of 0-30 km. Although variation in key biological characteristics has been explored on the scale of 100-1000 s of km, it has rarely been explored at the scale relevant to actual larval dispersal and population connectivity on ecological timescales. In this study, we surveyed the habitat and collected specimens ( n = 447) of juvenile butterflyfish, Chaetodon vagabundus, at nine sites along an 80-km stretch of coastline in the central Philippines to identify variation in key life history parameters at a spatial scale relevant to population connectivity. Mean pelagic larval duration (PLD) was 24.03 d (SE = 0.16 d), and settlement size was estimated to be 20.54 mm total length (TL; SE = 0.61 mm). Both traits were spatially consistent, although this PLD is considerably shorter than that reported elsewhere. In contrast, post-settlement daily growth rates, calculated from otolith increment widths from 1 to 50 d post-settlement, varied strongly across the study region. Elevated growth rates were associated with rocky habitats that this species is known to recruit to, but were strongly negatively correlated with macroalgal cover and exhibited negative density dependence with conspecific juveniles. Larger animals had lower early (first 50 d post-settlement) growth rates than smaller animals, even after accounting for seasonal variation in growth rates. Both VBGF and Gompertz models provided good fits to post-settlement size-at-age data ( n = 447 fish), but the VBGF's estimate of asymptotic length ( L ∞ = 168 mm) was more consistent with field observations of maximum fish length. Our findings indicate that larval characteristics are consistent at the spatial scale at which populations are likely well connected, but that site-level biological differences develop post-settlement, most likely as a

  16. Theory of dispersive microlenses

    NASA Technical Reports Server (NTRS)

    Herman, B.; Gal, George

    1993-01-01

    A dispersive microlens is a miniature optical element which simultaneously focuses and disperses light. Arrays of dispersive mircolenses have potential applications in multicolor focal planes. They have a 100 percent optical fill factor and can focus light down to detectors of diffraction spot size, freeing up areas on the focal plane for on-chip analog signal processing. Use of dispersive microlenses allows inband color separation within a pixel and perfect scene registration. A dual-color separation has the potential for temperature discrimination. We discuss the design of dispersive microlenses and present sample results for efficient designs.

  17. Neotropical fish-fruit interactions: eco-evolutionary dynamics and conservation.

    PubMed

    Correa, Sandra Bibiana; Costa-Pereira, Raul; Fleming, Theodore; Goulding, Michael; Anderson, Jill T

    2015-11-01

    Frugivorous fish play a prominent role in seed dispersal and reproductive dynamics of plant communities in riparian and floodplain habitats of tropical regions worldwide. In Neotropical wetlands, many plant species have fleshy fruits and synchronize their fruiting with the flood season, when fruit-eating fish forage in forest and savannahs for periods of up to 7 months. We conducted a comprehensive analysis to examine the evolutionary origin of fish-fruit interactions, describe fruit traits associated with seed dispersal and seed predation, and assess the influence of fish size on the effectiveness of seed dispersal by fish (ichthyochory). To date, 62 studies have documented 566 species of fruits and seeds from 82 plant families in the diets of 69 Neotropical fish species. Fish interactions with flowering plants are likely to be as old as 70 million years in the Neotropics, pre-dating most modern bird-fruit and mammal-fruit interactions, and contributing to long-distance seed dispersal and possibly the radiation of early angiosperms. Ichthyochory occurs across the angiosperm phylogeny, and is more frequent among advanced eudicots. Numerous fish species are capable of dispersing small seeds, but only a limited number of species can disperse large seeds. The size of dispersed seeds and the probability of seed dispersal both increase with fish size. Large-bodied species are the most effective seed dispersal agents and remain the primary target of fishing activities in the Neotropics. Thus, conservation efforts should focus on these species to ensure continuity of plant recruitment dynamics and maintenance of plant diversity in riparian and floodplain ecosystems. PMID:25599800

  18. Device Connectivity

    PubMed Central

    Walsh, John; Roberts, Ruth; Morris, Richard

    2015-01-01

    Patients with diabetes have to take numerous factors/data into their therapeutic decisions in daily life. Connecting the devices they are using by feeding the data generated into a database/app is supposed to help patients to optimize their glycemic control. As this is not established in practice, the different roadblocks have to be discussed to open the road. That large telecommunication companies are now entering this market might be a big help in pushing this forward. Smartphones offer an ideal platform for connectivity solutions. PMID:25614015

  19. The effect of fish meal replacement by soyabean products on fish growth: a meta-analysis.

    PubMed

    Sales, James

    2009-12-01

    Meta-analysis was applied to quantify the effect of replacement of fish meal by soyabean products in diets on fish growth. Measurement of growth in different units among studies required the use of a standardised effect size (Hedges' d). From a total of ninety-nine studies concentrating on fish meal replacement by defatted soyabean meal, 53 % were eliminated due to, among others, absence of a fish meal control diet (n 18), or no statistical differences or measurement of dispersion (n 6) indicated. Replacement of 4 to 40 % fish meal by soyabean meal (inclusion levels of 71-366 g/kg) resulted in a mean effect size of - 0.1142 (95 % CI - 0.4665, 0.2382) obtained in forty-eight comparisons evaluated with seventeen different fish species. However, at higher fish meal replacement levels the 95 % CI calculated for combined effect sizes did not overlap with zero. With soya protein concentrate replacing 25 to 100 % of fish meal in diets for seven fish species, methionine supplementation (mean - 2.4373 (95 % CI - 3.9004, - 0.9742); n 10) did not have a substantial influence on the magnitude of cumulative effect sizes relative to no supplementation (mean - 2.7306 (95 % CI - 3.7991, - 1.6620); n 16). Information on other soyabean products (full-fat soyabeans, soya flour) used as protein sources in fish diets was found as too limited for analysis and definite conclusions. The present study contributes by putting a numerical value to the magnitude of growth differences in fish when replacing dietary fish meal by soyabean products. PMID:20003609

  20. Population Structure and Phylogeography in Nassau Grouper (Epinephelus striatus), a Mass-Aggregating Marine Fish

    PubMed Central

    Jackson, Alexis M.; Semmens, Brice X.; Sadovy de Mitcheson, Yvonne; Nemeth, Richard S.; Heppell, Scott A.; Bush, Phillippe G.; Aguilar-Perera, Alfonso; Claydon, John A. B.; Calosso, Marta C.; Sealey, Kathleen S.; Schärer, Michelle T.; Bernardi, Giacomo

    2014-01-01

    To address patterns of genetic connectivity in a mass-aggregating marine fish, we analyzed genetic variation in mitochondrial DNA (mtDNA), microsatellites, and single nucleotide polymorphisms (SNPs) for Nassau grouper (Epinephelus striatus). We expected Nassau grouper to exhibit genetic differentiation among its subpopulations due to its reproductive behavior and retentive oceanographic conditions experienced across the Caribbean basin. All samples were genotyped for two mitochondrial markers and 9 microsatellite loci, and a subset of samples were genotyped for 4,234 SNPs. We found evidence of genetic differentiation in a Caribbean-wide study of this mass-aggregating marine fish using mtDNA (FST = 0.206, p<0.001), microsatellites (FST = 0.002, p = 0.004) and SNPs (FST = 0.002, p = 0.014), and identified three potential barriers to larval dispersal. Genetically isolated regions identified in our work mirror those seen for other invertebrate and fish species in the Caribbean basin. Oceanographic regimes in the Caribbean may largely explain patterns of genetic differentiation among Nassau grouper subpopulations. Regional patterns observed warrant standardization of fisheries management and conservation initiatives among countries within genetically isolated regions. PMID:24830641

  1. Defining Boundaries for Ecosystem-Based Management: A Multispecies Case Study of Marine Connectivity across the Hawaiian Archipelago

    PubMed Central

    Toonen, Robert J.; Andrews, Kimberly R.; Baums, Iliana B.; Bird, Christopher E.; Concepcion, Gregory T.; Daly-Engel, Toby S.; Eble, Jeff A.; Faucci, Anuschka; Gaither, Michelle R.; Iacchei, Matthew; Puritz, Jonathan B.; Schultz, Jennifer K.; Skillings, Derek J.; Timmers, Molly A.; Bowen, Brian W.

    2014-01-01

    Determining the geographic scale at which to apply ecosystem-based management (EBM) has proven to be an obstacle for many marine conservation programs. Generalizations based on geographic proximity, taxonomy, or life history characteristics provide little predictive power in determining overall patterns of connectivity, and therefore offer little in terms of delineating boundaries for marine spatial management areas. Here, we provide a case study of 27 taxonomically and ecologically diverse species (including reef fishes, marine mammals, gastropods, echinoderms, cnidarians, crustaceans, and an elasmobranch) that reveal four concordant barriers to dispersal within the Hawaiian Archipelago which are not detected in single-species exemplar studies. We contend that this multispecies approach to determine concordant patterns of connectivity is an objective and logical way in which to define the minimum number of management units and that EBM in the Hawaiian Archipelago requires at least five spatially managed regions. PMID:25505913

  2. Dispersal kernel estimation: A comparison of empirical and modelled particle dispersion in a coastal marine system

    NASA Astrophysics Data System (ADS)

    Hrycik, Janelle M.; Chassé, Joël; Ruddick, Barry R.; Taggart, Christopher T.

    2013-11-01

    Early life-stage dispersal influences recruitment and is of significance in explaining the distribution and connectivity of marine species. Motivations for quantifying dispersal range from biodiversity conservation to the design of marine reserves and the mitigation of species invasions. Here we compare estimates of real particle dispersion in a coastal marine environment with similar estimates provided by hydrodynamic modelling. We do so by using a system of magnetically attractive particles (MAPs) and a magnetic-collector array that provides measures of Lagrangian dispersion based on the time-integration of MAPs dispersing through the array. MAPs released as a point source in a coastal marine location dispersed through the collector array over a 5-7 d period. A virtual release and observed (real-time) environmental conditions were used in a high-resolution three-dimensional hydrodynamic model to estimate the dispersal of virtual particles (VPs). The number of MAPs captured throughout the collector array and the number of VPs that passed through each corresponding model location were enumerated and compared. Although VP dispersal reflected several aspects of the observed MAP dispersal, the comparisons demonstrated model sensitivity to the small-scale (random-walk) particle diffusivity parameter (Kp). The one-dimensional dispersal kernel for the MAPs had an e-folding scale estimate in the range of 5.19-11.44 km, while those from the model simulations were comparable at 1.89-6.52 km, and also demonstrated sensitivity to Kp. Variations among comparisons are related to the value of Kp used in modelling and are postulated to be related to MAP losses from the water column and (or) shear dispersion acting on the MAPs; a process that is constrained in the model. Our demonstration indicates a promising new way of 1) quantitatively and empirically estimating the dispersal kernel in aquatic systems, and 2) quantitatively assessing and (or) improving regional hydrodynamic

  3. Impact of dispersal on the stability of metapopulations.

    PubMed

    Tromeur, Eric; Rudolf, Lars; Gross, Thilo

    2016-03-01

    Dispersal is a key ecological process that enables local populations to form spatially extended systems called metapopulations. In the present study, we investigate how dispersal affects the linear stability of a general single-species metapopulation model. We discuss both the influence of local within-patch dynamics and the effects of various dispersal behaviours on stability. We find that positive density-dependent dispersal and positive density-dependent settlement are destabilizing dispersal behaviours while negative density-dependent dispersal and negative density-dependent settlement are stabilizing. It is also shown that dispersal has a stabilizing impact on heterogeneous metapopulations that correlates positively with the number of patches and the connectance of metapopulation networks. PMID:26723533

  4. Connecting Node

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.; Raboin, Jasen L.; Spexarth, Gary R.

    2009-01-01

    A paper describes the Octanode, a connecting node that facilitates the integration of multiple docking mechanisms, hatches, windows, and internal and external systems with the use of flat surfaces. The Octanode is a 26- faced Great Rhombicuboctahedron Archi medean solid with six octagonshaped panels, eight hexagon-shaped panels, and 12 square panels using three unique, simple, flat shapes to construct a spherical approximation. Each flat shape can be constructed with a variety of material and manufacturing techniques, such as honeycomb composite panels or a pocketed skinstringer configuration, using conventional means. The flat shapes can be connected together and sealed to create a pressurizable volume by the use of any conventional means including welding or fastening devices and sealant. The node can then be connected to other elements to allow transfer between those elements, or it could serve as an airlock. The Octanode can be manufactured on the ground and can be integrated with subsystems including hatches and ports. The node can then be transported to its intended location, whether on orbit or on surface. Any of the flat panels could be replaced by curved ones, turning the node into a copula. Windows may be placed on flat panes with optimal viewing angles that are not blocked by large connecting nodes. The advantage of using flat panels to represent a spherical approximation is that this allows for easier integration of subsystems and design features.

  5. Get Connected

    ERIC Educational Resources Information Center

    Horton, Jessica; Hagevik, Rita; Adkinson, Bennett; Parmly, Jilynn

    2013-01-01

    Technology can be both a blessing and a curse in the classroom. Although technology can provide greater access to information and increase student engagement, if screen time replaces time spent outside, then students stand to lose awareness and connectivity to the surrounding natural environment. This article describes how Google Earth can foster…

  6. Making Connections

    ERIC Educational Resources Information Center

    Quillen, Ian

    2014-01-01

    "We used to send out books that looked like this," says Barbara Dreyer, as she holds the 500-page volume from one of the first-ever courses offered online by Connections Academy. "You could look at this information online, but, frankly, a lot of people were doing this," she adds, thumbing through the book's pages. Dreyer,…

  7. Learning Connections

    ERIC Educational Resources Information Center

    Royer, Regina D.; Richards, Patricia O.

    2005-01-01

    In this edition of Learning Connections, the authors show how technology can enhance study of weather patterns, reading comprehension, real-world training, critical thinking, health education, and art criticism. The following sections are included: (1) Social Studies; (2) Language Arts; (3) Computer Science and ICT; (4) Art; and (5) Health.…

  8. College Connection

    ERIC Educational Resources Information Center

    Hewitt, Kimberly Kappler; Scalzo, Mary Jo

    2012-01-01

    This article describes Oakwood City School District's College Connection Study, which is now in its eighth year. The purpose of the study is to help the educators in the district learn how to effectively prepare students for success in the colleges of their choice. Teachers, administrators, and other staff members travel to colleges to conduct…

  9. Fish population persistence in hydrologically variable landscapes.

    PubMed

    Bond, Nick R; Balcombe, Stephen R; Crook, David A; Marshall, Jonathan C; Menke, Norbert; Lobegeiger, Jaye S

    2015-06-01

    Forecasting population persistence in environments subjected to periodic disturbances represents a general challenge for ecologists. In arid and semiarid regions, climate change and human water use pose significant threats to the future persistence of aquatic biota whose populations typically depend on permanent refuge waterholes for their viability. As such, habitats are increasingly being lost as a result of decreasing runoff and increasing water extraction. We constructed a spatially explicit population model for golden perch Macquaria ambigua (Richardson), a native freshwater fish in the Murray-Darling Basin in eastern Australia. We then used the model to examine the effects of increased aridity, increased drought frequency, and localized human water extraction on population viability. Consistent with current observations, the model predicted golden perch population persistence under the current climate and levels of water use. Modeled increases in local water extraction greatly increased the risk of population decline, while scenarios of increasing aridity and drought frequency were associated with only minor increases in this risk. We conclude that natural variability in abundances and high turnover rates (extinction/recolonization) of local populations dictate the importance of spatial connectivity and periodic cycles of population growth. Our study also demonstrates an effective way to examine population persistence in intermittent and ephemeral river systems by integrating spatial and temporal dynamics of waterhole persistence with demographic processes (survival, recruitment, and dispersal) within a stochastic modeling framework. The approach can be used to help understand the impacts of natural and anthropogenic drivers, including water resource development, on the viability of biota inhabiting highly dynamic environments. PMID:26465032

  10. Detail of gate, gate slots, and connection between the two ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of gate, gate slots, and connection between the two segments of the rectangular rearing tank. Pump house (1962) at entrance is in the background. View to the southwest. - Prairie Creek Fish Hatchery, Hwy. 101, Orick, Humboldt County, CA

  11. Effects of Acclimation on Poststocking Dispersal and Physiological Condition of Age-1 Pallid Sturgeon

    SciTech Connect

    Oldenburg, Eric W.; Guy, Christopher S.; Cureton, Eli S.; Webb, Molly H.; Gardner, William M.

    2011-03-28

    A propagation program for pallid sturgeon Scaphirhynchus albus in the upper Missouri River was implemented by the U. S. Fish and Wildlife Service in 1997. Preliminary research indicated that many hatchery-reared pallid sturgeon were experiencing significant downstream poststocking dispersal, negatively affecting their recruitment. Therefore, the objective of this study was to evaluate the effects of acclimation to flow and site-specific physicochemical water conditions on poststocking dispersal and physiological condition of age-1 pallid sturgeon. Fish from three acclimation treatments were radio-tagged, released at two locations (Missouri River and Marias River), and monitored using passive telemetry stations. Marias treatment was acclimated to flow and site-specific physicochemical conditions, Bozeman treatment was acclimated to flow only, and traditional treatment had no acclimation (reared under traditional protocol). During both years fish released in the Missouri River dispersed less than fish released in the Marias River. In 2005, Marias treatment dispersed less and nearly twice as many fish remained in the Missouri River reach than traditional treatment. In 2006, pallid sturgeon dispersed similarly among treatments and fish remaining in the Missouri River reach were similar among all treatments. Differences in poststocking dispersal between years may be related to fin curl. Fin curl was present in all fish in 2005 and 27% of the fish in 2006. Pallid sturgeon from all treatments in both years had a greater affinity for the lower reaches of the Missouri River than the upper reaches. Thus, habitat at release site influenced poststocking dispersal more than acclimation treatment. No difference was observed in relative growth rate among treatments in 2006. However, acclimation to flow (i.e., exercise conditioning) may reduce liver fat content. Acclimation conditions used in this study may not benefit pallid sturgeon unless physiological maladies are present

  12. 26 CFR 31.3306(c)(17)-1 - Fishing services.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 15 2012-04-01 2012-04-01 false Fishing services. 31.3306(c)(17)-1 Section 31... Fishing services. (a) In general. Subject to the limitations prescribed in paragraphs (b) and (c) of this...) Salmon and halibut fishing. Services performed in connection with the catching or taking of salmon...

  13. Landscape-scale food webs of fish nursery habitat along a river-coast mixing zone

    EPA Science Inventory

    We used carbon and nitrogen stable isotope analysis to study connections between allochthonous energy use and ecological connectivity of fish larvae in a complex coastal mosaic. We quantified fish larvae support by autochthonous and allochthonous material in three coastal river-w...

  14. Fish biodiversity and conservation in South America.

    PubMed

    Reis, R E; Albert, J S; Di Dario, F; Mincarone, M M; Petry, P; Rocha, L A

    2016-07-01

    The freshwater and marine fish faunas of South America are the most diverse on Earth, with current species richness estimates standing above 9100 species. In addition, over the last decade at least 100 species were described every year. There are currently about 5160 freshwater fish species, and the estimate for the freshwater fish fauna alone points to a final diversity between 8000 and 9000 species. South America also has c. 4000 species of marine fishes. The mega-diverse fish faunas of South America evolved over a period of >100 million years, with most lineages tracing origins to Gondwana and the adjacent Tethys Sea. This high diversity was in part maintained by escaping the mass extinctions and biotic turnovers associated with Cenozoic climate cooling, the formation of boreal and temperate zones at high latitudes and aridification in many places at equatorial latitudes. The fresh waters of the continent are divided into 13 basin complexes, large basins consolidated as a single unit plus historically connected adjacent coastal drainages, and smaller coastal basins grouped together on the basis of biogeographic criteria. Species diversity, endemism, noteworthy groups and state of knowledge of each basin complex are described. Marine habitats around South America, both coastal and oceanic, are also described in terms of fish diversity, endemism and state of knowledge. Because of extensive land use changes, hydroelectric damming, water divergence for irrigation, urbanization, sedimentation and overfishing 4-10% of all fish species in South America face some degree of extinction risk, mainly due to habitat loss and degradation. These figures suggest that the conservation status of South American freshwater fish faunas is better than in most other regions of the world, but the marine fishes are as threatened as elsewhere. Conserving the remarkable aquatic habitats and fishes of South America is a growing challenge in face of the rapid anthropogenic changes of the 21

  15. Fish-assemblage variation between geologically defined regions and across a longitudinal gradient in the Monkey River Basin, Belize

    USGS Publications Warehouse

    Esselman, P.C.; Freeman, Mary C.; Pringle, C.M.

    2006-01-01

    assemblage structure within each geologic type. The fauna showed weak compositional zonation into 3 groups (headwaters, coastal plain, and nearshore). Nearly 20% of the fish species collected have migratory life cycles (including Joturus pichardi, Agonostomus monticola, and Gobiomorus dormitor) that use freshwater and marine habitats. Some of these species probably rely on a natural flow regime and longitudinal connectivity for reproduction and dispersal of young, and natural flow regime and longitudinal connectivity are important factors for maintenance of functional linkages between the uplands and the coast in the ridge-to-reef corridor where the Monkey River is located. Therefore, we suggest that the viability of migratory fish populations may be a good biological indicator of upland-to-estuary connectivity important both to fishes and coastal ecosystem function. We recommend follow-up studies to substantiate the relative strengths of relationships between community structure and abiotic factors in contrasting geologies and to examine potential bottom-up responses of stream biota to the higher nutrient levels that were observed in stream waters draining the Santa Rosa Group geologic type.

  16. Visualizing Dispersion Interactions

    ERIC Educational Resources Information Center

    Gottschalk, Elinor; Venkataraman, Bhawani

    2014-01-01

    An animation and accompanying activity has been developed to help students visualize how dispersion interactions arise. The animation uses the gecko's ability to walk on vertical surfaces to illustrate how dispersion interactions play a role in macroscale outcomes. Assessment of student learning reveals that students were able to develop…

  17. Spores Disperse, Too!

    ERIC Educational Resources Information Center

    Schumann, Donna N.

    1981-01-01

    Suggests the use of spores and spore-producing structures to show adaptations facilitating spore dispersal and dispersal to favorable environments. Describes several activities using horsetails, ferns, and mosses. Lists five safety factors related to use of mold spores in the classroom. (DS)

  18. Dispersion strengthened copper

    DOEpatents

    Sheinberg, H.; Meek, T.T.; Blake, R.D.

    1990-01-09

    A composition of matter is described which is comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide. A method for making this composition of matter is also described. This invention relates to the art of powder metallurgy and, more particularly, it relates to dispersion strengthened metals.

  19. Dispersal of forest insects

    NASA Technical Reports Server (NTRS)

    Mcmanus, M. L.

    1979-01-01

    Dispersal flights of selected species of forest insects which are associated with periodic outbreaks of pests that occur over large contiguous forested areas are discussed. Gypsy moths, spruce budworms, and forest tent caterpillars were studied for their massive migrations in forested areas. Results indicate that large dispersals into forested areas are due to the females, except in the case of the gypsy moth.

  20. A Column Dispersion Experiment.

    ERIC Educational Resources Information Center

    Corapcioglu, M. Y.; Koroglu, F.

    1982-01-01

    Crushed glass and a Rhodamine B solution are used in a one-dimensional optically scanned column experiment to study the dispersion phenomenon in porous media. Results indicate that the described model gave satisfactory results and that the dispersion process in this experiment is basically convective. (DC)

  1. Dispersion and space charge

    NASA Astrophysics Data System (ADS)

    Venturini, Marco; Kishek, Rami A.; Reiser, Martin

    1998-11-01

    The presence of space charge affects the value of the dispersion function. On the other hand dispersion has a role in shaping the beam distribution and therefore in determining the resulting forces due to space charge. In this paper we present a framework where the interplay between space charge and dispersion for a continuous beam can be simultaneously treated. We revise the derivation of a new set of rms envelope-dispersion equations we have recently proposed in [1]. The new equations generalize the standard rms envelope equations currently used for matching to the case where bends and a longitudinal momentum spread are present. We report a comparison between the solutions of the rms envelope-dispersion equations and the results obtained using WARP, a Particle in Cell (PIC) code, in the modeling of the Maryland Electron Ring.

  2. Dispersion dipoles for coupled Drude oscillators

    NASA Astrophysics Data System (ADS)

    Odbadrakh, Tuguldur T.; Jordan, Kenneth D.

    2016-01-01

    We present the dispersion-induced dipole moments of coupled Drude oscillators obtained from two approaches. The first approach evaluates the dipole moment using the second-order Rayleigh-Schrödinger perturbation theory wave function allowing for dipole-dipole and dipole-quadrupole coupling. The second approach, based on response theory, employs an integral of the dipole-dipole polarizability of one oscillator and the dipole-dipole-quadrupole hyperpolarizability of the other oscillator over imaginary frequencies. The resulting dispersion dipoles exhibit an R-7 dependence on the separation between the two oscillators and are connected to the leading-order C6/R6 dispersion energy through the electrostatic Hellmann-Feynman theorem.

  3. Reservoir floodplains support distinct fish assemblages

    USGS Publications Warehouse

    Miranda, Leandro E.; Wigen, S. L.; Dagel, Jonah D.

    2014-01-01

    Reservoirs constructed on floodplain rivers are unique because the upper reaches of the impoundment may include extensive floodplain environments. Moreover, reservoirs that experience large periodic water level fluctuations as part of their operational objectives seasonally inundate and dewater floodplains in their upper reaches, partly mimicking natural inundations of river floodplains. In four flood control reservoirs in Mississippi, USA, we explored the dynamics of connectivity between reservoirs and adjacent floodplains and the characteristics of fish assemblages that develop in reservoir floodplains relative to those that develop in reservoir bays. Although fish species richness in floodplains and bays were similar, species composition differed. Floodplains emphasized fish species largely associated with backwater shallow environments, often resistant to harsh environmental conditions. Conversely, dominant species in bays represented mainly generalists that benefit from the continuous connectivity between the bay and the main reservoir. Floodplains in the study reservoirs provided desirable vegetated habitats at lower water level elevations, earlier in the year, and more frequently than in bays. Inundating dense vegetation in bays requires raising reservoir water levels above the levels required to reach floodplains. Therefore, aside from promoting distinct fish assemblages within reservoirs and helping promote diversity in regulated rivers, reservoir floodplains are valued because they can provide suitable vegetated habitats for fish species at elevations below the normal pool, precluding the need to annually flood upland vegetation that would inevitably be impaired by regular flooding. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  4. Fish as a proxy for African paleogeography: results from both extant and fossil taxa and prospects to constrain faunal exchange pathway through time

    NASA Astrophysics Data System (ADS)

    Otero, Olga; Joordens, Josephine; Dettai, Agnès; Christ, Leemans; Pinton, Aurélie

    2016-04-01

    We assume that basin boundaries constitute barriers to dispersal for freshwater fish and as a consequence that basin geomorphology and connectivity, and its changes through time, can be reconstructed thanks to fish evolutionary history. Firstly, this primary intuitive hypothesis is supported by patterns of fish distribution in the different basins and sub-basins of modern Africa, at both a specific and a generic level, and in certain cases at a family level. This is illustrated by the fact that hydrographical basin boundaries are reflected in the ichthyological provinces as defined and used by ichthyologists for a long time. Moreover, we show that at a continental scale, the hierarchical fish distribution patterns fit with main geological and climatic events according to their depth in time and amplitude [1]. Secondly, we further tested this hypothesis in several ways: (1) through the phylogeographical study of the catfish genus Synodontis [2], chosen because of its modern distribution and its rich fossil record, and (2) through the examination of the fossil record and systematics of the African lungfish Protopterus [3], of the catfish Calarius and of an extinct acanthomorph fish called Semlikiichthys [4,5]. We were then able to correlate these fish histories with quaternary climate change and with geological events throughout the Tertiary in Africa. Our conclusions are also corroborated by existing fish phylogenies that overlap with our region of interest, and elsewhere. While in the last years an increasing number of molecular phylogenetical studies support correlation between fish evolution and basin history at shallow time scales, our studies (and a few other studies) also demonstrate the relevance of fish evolution to work at deeper time and larger geological scales, depending on the taxon distribution and age. Moreover, we plead for the inclusion of fossils when available. Indeed, for extant taxa they are useful to calibrate molecular clocks but also to

  5. Patterns and mechanisms of dispersal in a keystone seagrass species.

    PubMed

    Jahnke, Marlene; Christensen, Asbjørn; Micu, Dragos; Milchakova, Nataliya; Sezgin, Murat; Todorova, Valentina; Strungaru, Stefan; Procaccini, Gabriele

    2016-06-01

    Mechanisms and vectors of long-distance dispersal remain unknown for many coastal benthic species, including plants. Indications for the possibility for long-distance dispersal come from dispersal modelling and from genetic assessments, but have rarely been assessed with both methods. To this end, we assessed dispersal of the seagrass Zostera noltei, an important foundation species of the coastal zone. We investigate whether small scale seed dispersal and long-distance propagule dispersal do play a role for meta-population dynamics, using both genetic assessments based on eight microsatellite markers and physical modelling of ocean currents. Such assessments enhance our understanding of the biology and population dynamics of an important coastal foundation species. They are relevant for large scale conservation strategies as they give insights in the maintenance of genetic diversity and connectivity that may enhance resilience and resistance to stresses associated with seagrass loss. PMID:27085058

  6. Scorpion fish sting

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002849.htm Scorpion fish sting To use the sharing features on this page, please enable JavaScript. Scorpion fish are members of the family Scorpaenidae, which includes ...

  7. Poisoning - fish and shellfish

    MedlinePlus

    Fish poisoning; Dinoflagellate poisoning; Seafood contamination; Paralytic shellfish poisoning; Ciguatera poisoning ... algae and algae-like organisms called dinoflagellates. Small fish that eat the algae become contaminated. If larger ...

  8. 49 CFR 173.218 - Fish meal or fish scrap.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Fish meal or fish scrap. 173.218 Section 173.218... Fish meal or fish scrap. (a) Except as provided in Column (7) of the HMT in § 172.101 of this subchapter, fish meal or fish scrap, containing at least 6%, but not more than 12% water, is authorized...

  9. 46 CFR 148.265 - Fish meal or fish scrap.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Fish meal or fish scrap. 148.265 Section 148.265... MATERIALS THAT REQUIRE SPECIAL HANDLING Special Requirements for Certain Materials § 148.265 Fish meal or fish scrap. (a) This part does not apply to fish meal or fish scrap that contains less than 5...

  10. 49 CFR 173.218 - Fish meal or fish scrap.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Fish meal or fish scrap. 173.218 Section 173.218... Fish meal or fish scrap. (a) Except as provided in Column (7) of the HMT in § 172.101 of this subchapter, fish meal or fish scrap, containing at least 6%, but not more than 12% water, is authorized...

  11. 46 CFR 148.265 - Fish meal or fish scrap.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Fish meal or fish scrap. 148.265 Section 148.265... MATERIALS THAT REQUIRE SPECIAL HANDLING Special Requirements for Certain Materials § 148.265 Fish meal or fish scrap. (a) This part does not apply to fish meal or fish scrap that contains less than 5...

  12. 46 CFR 148.265 - Fish meal or fish scrap.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Fish meal or fish scrap. 148.265 Section 148.265... MATERIALS THAT REQUIRE SPECIAL HANDLING Special Requirements for Certain Materials § 148.265 Fish meal or fish scrap. (a) This part does not apply to fish meal or fish scrap that contains less than 5...

  13. 46 CFR 148.265 - Fish meal or fish scrap.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Fish meal or fish scrap. 148.265 Section 148.265... MATERIALS THAT REQUIRE SPECIAL HANDLING Special Requirements for Certain Materials § 148.265 Fish meal or fish scrap. (a) This part does not apply to fish meal or fish scrap that contains less than 5...

  14. 49 CFR 173.218 - Fish meal or fish scrap.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Fish meal or fish scrap. 173.218 Section 173.218... Fish meal or fish scrap. (a) Except as provided in Column (7) of the HMT in § 172.101 of this subchapter, fish meal or fish scrap, containing at least 6%, but not more than 12% water, is authorized...

  15. 49 CFR 173.218 - Fish meal or fish scrap.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Fish meal or fish scrap. 173.218 Section 173.218... Fish meal or fish scrap. (a) Except as provided in Column (7) of the HMT in § 172.101 of this subchapter, fish meal or fish scrap, containing at least 6%, but not more than 12% water, is authorized...

  16. 49 CFR 173.218 - Fish meal or fish scrap.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Fish meal or fish scrap. 173.218 Section 173.218... Fish meal or fish scrap. (a) Except as provided in Column (7) of the HMT in § 172.101 of this subchapter, fish meal or fish scrap, containing at least 6%, but not more than 12% water, is authorized...

  17. Coral reef fish populations can persist without immigration.

    PubMed

    Salles, Océane C; Maynard, Jeffrey A; Joannides, Marc; Barbu, Corentin M; Saenz-Agudelo, Pablo; Almany, Glenn R; Berumen, Michael L; Thorrold, Simon R; Jones, Geoffrey P; Planes, Serge

    2015-11-22

    Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase. PMID:26582017

  18. Poisoning - fish and shellfish

    MedlinePlus

    ... contaminated waters. Scombroid poisoning usually occurs from large, dark meat fish such as tuna, mackerel, mahi mahi, and albacore. Because this poison develops after a fish is caught and dies, it does not matter where the fish is caught. The main factor ...

  19. Fish Health Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For commercial success, a recirculating aquaculture operation must maintain fish at densities far greater than normally found in nature. At the same time, the producer must maintain an environment that supports good fish health. This chapter discusses various aspects of fish health management, inclu...

  20. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

    1990-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  1. Dispersion strengthened copper

    DOEpatents

    Sheinberg, Haskell; Meek, Thomas T.; Blake, Rodger D.

    1989-01-01

    A composition of matter comprised of copper and particles which are dispersed throughout the copper, where the particles are comprised of copper oxide and copper having a coating of copper oxide, and a method for making this composition of matter.

  2. Dendritic connectivity controls biodiversity patterns in experimental metacommunities

    PubMed Central

    Carrara, Francesco; Altermatt, Florian; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2012-01-01

    Biological communities often occur in spatially structured habitats where connectivity directly affects dispersal and metacommunity processes. Recent theoretical work suggests that dispersal constrained by the connectivity of specific habitat structures, such as dendrites like river networks, can explain observed features of biodiversity, but direct evidence is still lacking. We experimentally show that connectivity per se shapes diversity patterns in microcosm metacommunities at different levels. Local dispersal in isotropic lattice landscapes homogenizes local species richness and leads to pronounced spatial persistence. On the contrary, dispersal along dendritic landscapes leads to higher variability in local diversity and among-community composition. Although headwaters exhibit relatively lower species richness, they are crucial for the maintenance of regional biodiversity. Our results establish that spatially constrained dendritic connectivity is a key factor for community composition and population persistence. PMID:22460788

  3. Nanocrystal dispersed amorphous alloys

    NASA Technical Reports Server (NTRS)

    Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

    2001-01-01

    Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

  4. Fickian dispersion is anomalous

    SciTech Connect

    Cushman, John H.; O’Malley, Dan

    2015-06-22

    The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion we illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Finally, power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.

  5. Fickian dispersion is anomalous

    DOE PAGESBeta

    Cushman, John H.; O’Malley, Dan

    2015-06-22

    The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion wemore » illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Finally, power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.« less

  6. Fish under exercise.

    PubMed

    Palstra, Arjan P; Planas, Josep V

    2011-06-01

    Improved knowledge on the swimming physiology of fish and its application to fisheries science and aquaculture (i.e., farming a fitter fish) is currently needed in the face of global environmental changes, high fishing pressures, increased aquaculture production as well as increased concern on fish well-being. Here, we review existing data on teleost fish that indicate that sustained exercise at optimal speeds enhances muscle growth and has consequences for flesh quality. Potential added benefits of sustained exercise may be delay of ovarian development and stimulation of immune status. Exercise could represent a natural, noninvasive, and economical approach to improve growth, flesh quality as well as welfare of aquacultured fish: a FitFish for a healthy consumer. All these issues are important for setting directions for policy decisions and future studies in this area. For this purpose, the FitFish workshop on the Swimming Physiology of Fish ( http://www.ub.edu/fitfish2010 ) was organized to bring together a multidisciplinary group of scientists using exercise models, industrial partners, and policy makers. Sixteen international experts from Europe, North America, and Japan were invited to present their work and view on migration of fishes in their natural environment, beneficial effects of exercise, and applications for sustainable aquaculture. Eighty-eight participants from 19 different countries contributed through a poster session and round table discussion. Eight papers from invited speakers at the workshop have been contributed to this special issue on The Swimming Physiology of Fish. PMID:21611721

  7. Fish allergy: in review.

    PubMed

    Sharp, Michael F; Lopata, Andreas L

    2014-06-01

    Globally, the rising consumption of fish and its derivatives, due to its nutritional value and divergence of international cuisines, has led to an increase in reports of adverse reactions to fish. Reactions to fish are not only mediated by the immune system causing allergies, but are often caused by various toxins and parasites including ciguatera and Anisakis. Allergic reactions to fish can be serious and life threatening and children usually do not outgrow this type of food allergy. The route of exposure is not only restricted to ingestion but include manual handling and inhalation of cooking vapors in the domestic and occupational environment. Prevalence rates of self-reported fish allergy range from 0.2 to 2.29 % in the general population, but can reach up to 8 % among fish processing workers. Fish allergy seems to vary with geographical eating habits, type of fish processing, and fish species exposure. The major fish allergen characterized is parvalbumin in addition to several less well-known allergens. This contemporary review discusses interesting and new findings in the area of fish allergy including demographics, novel allergens identified, immunological mechanisms of sensitization, and innovative approaches in diagnosing and managing this life-long disease. PMID:23440653

  8. Native fish conservation areas: A vision for large-scale conservation of native fish communities

    USGS Publications Warehouse

    Williams, Jack E.; Williams, Richard N.; Thurow, Russell F.; Elwell, Leah; Philipp, David P.; Harris, Fred A.; Kershner, Jeffrey L.; Martinez, Patrick J.; Miller, Dirk; Reeves, Gordon H.; Frissell, Christopher A.; Sedell, James R.

    2011-01-01

    The status of freshwater fishes continues to decline despite substantial conservation efforts to reverse this trend and recover threatened and endangered aquatic species. Lack of success is partially due to working at smaller spatial scales and focusing on habitats and species that are already degraded. Protecting entire watersheds and aquatic communities, which we term "native fish conservation areas" (NFCAs), would complement existing conservation efforts by protecting intact aquatic communities while allowing compatible uses. Four critical elements need to be met within a NFCA: (1) maintain processes that create habitat complexity, diversity, and connectivity; (2) nurture all of the life history stages of the fishes being protected; (3) include a long-term enough watershed to provide long-term persistence of native fish populations; and (4) provide management that is sustainable over time. We describe how a network of protected watersheds could be created that would anchor aquatic conservation needs in river basins across the country.

  9. Fish community results

    SciTech Connect

    Hickman, G.D.; Scott, E.M. Jr.; Brown, A.M.

    1991-05-01

    The Tennessee Valley Authority (TVA) operates 9 reservoirs on the Tennessee River and 37 reservoirs on its tributaries. TVA is committed to maintaining the health of aquatic resources created when the reservoir system was built. To that end, TVA in cooperation with Valley states, operates a water resource monitoring program that includes physical, chemical, and biological data collection components. Biological monitoring will target the following selected elements within three zones of the reservoir (inflow, transition, and forebay): Sediment/Water-column Acute Toxicity Screening, Benthic macroinvertebrates, and Fish. Reservoir fisheries monitoring is divided into the following activities: Fish Biomass, Fish Tissue Contamination, Fish Community Monitoring, and Fish Health Assessment. This report presents the results of fish community monitoring and fish health assessments.

  10. Looking for hotspots of marine metacommunity connectivity: a methodological framework.

    PubMed

    Melià, Paco; Schiavina, Marcello; Rossetto, Marisa; Gatto, Marino; Fraschetti, Simonetta; Casagrandi, Renato

    2016-01-01

    Seascape connectivity critically affects the spatiotemporal dynamics of marine metacommunities. Understanding how connectivity patterns emerge from physically and biologically-mediated interactions is therefore crucial to conserve marine ecosystem functions and biodiversity. Here, we develop a set of biophysical models to explore connectivity in assemblages of species belonging to a typical Mediterranean community (Posidonia oceanica meadows) and characterized by different dispersing traits. We propose a novel methodological framework to synthesize species-specific results into a set of community connectivity metrics and show that spatiotemporal variation in magnitude and direction of the connections, as well as interspecific differences in dispersing traits, are key factors structuring community connectivity. We eventually demonstrate how these metrics can be used to characterize the functional role of each marine area in determining patterns of community connectivity at the basin level and to support marine conservation planning. PMID:27029563

  11. Looking for hotspots of marine metacommunity connectivity: a methodological framework

    NASA Astrophysics Data System (ADS)

    Melià, Paco; Schiavina, Marcello; Rossetto, Marisa; Gatto, Marino; Fraschetti, Simonetta; Casagrandi, Renato

    2016-03-01

    Seascape connectivity critically affects the spatiotemporal dynamics of marine metacommunities. Understanding how connectivity patterns emerge from physically and biologically-mediated interactions is therefore crucial to conserve marine ecosystem functions and biodiversity. Here, we develop a set of biophysical models to explore connectivity in assemblages of species belonging to a typical Mediterranean community (Posidonia oceanica meadows) and characterized by different dispersing traits. We propose a novel methodological framework to synthesize species-specific results into a set of community connectivity metrics and show that spatiotemporal variation in magnitude and direction of the connections, as well as interspecific differences in dispersing traits, are key factors structuring community connectivity. We eventually demonstrate how these metrics can be used to characterize the functional role of each marine area in determining patterns of community connectivity at the basin level and to support marine conservation planning.

  12. Looking for hotspots of marine metacommunity connectivity: a methodological framework

    PubMed Central

    Melià, Paco; Schiavina, Marcello; Rossetto, Marisa; Gatto, Marino; Fraschetti, Simonetta; Casagrandi, Renato

    2016-01-01

    Seascape connectivity critically affects the spatiotemporal dynamics of marine metacommunities. Understanding how connectivity patterns emerge from physically and biologically-mediated interactions is therefore crucial to conserve marine ecosystem functions and biodiversity. Here, we develop a set of biophysical models to explore connectivity in assemblages of species belonging to a typical Mediterranean community (Posidonia oceanica meadows) and characterized by different dispersing traits. We propose a novel methodological framework to synthesize species-specific results into a set of community connectivity metrics and show that spatiotemporal variation in magnitude and direction of the connections, as well as interspecific differences in dispersing traits, are key factors structuring community connectivity. We eventually demonstrate how these metrics can be used to characterize the functional role of each marine area in determining patterns of community connectivity at the basin level and to support marine conservation planning. PMID:27029563

  13. Adaption of egg and larvae sampling techniques for lake sturgeon and broadcast spawning fishes in a deep river

    USGS Publications Warehouse

    Roseman, E.F.; Boase, J.; Kennedy, G.; Craig, J.; Soper, K.

    2011-01-01

    In this report we describe how we adapted two techniques for sampling lake sturgeon (Acipenser fulvescens) and other fish early life history stages to meet our research needs in the Detroit River, a deep, flowing Great Lakes connecting channel. First, we developed a buoy-less method for sampling fish eggs and spawning activity using egg mats deployed on the river bottom. The buoy-less method allowed us to fish gear in areas frequented by boaters and recreational anglers, thus eliminating surface obstructions that interfered with recreational and boating activities. The buoy-less method also reduced gear loss due to drift when masses of floating aquatic vegetation would accumulate on buoys and lines, increasing the drag on the gear and pulling it downstream. Second, we adapted a D-frame drift net system formerly employed in shallow streams to assess larval lake sturgeon dispersal for use in the deeper (>8m) Detroit River using an anchor and buoy system. ?? 2011 Blackwell Verlag, Berlin.

  14. Evidence of estuarine nursery origin of five coastal fish species along the Portuguese coast through otolith elemental fingerprints

    NASA Astrophysics Data System (ADS)

    Vasconcelos, Rita P.; Reis-Santos, Patrick; Tanner, Susanne; Maia, Anabela; Latkoczy, Christopher; Günther, Detlef; Costa, Maria José; Cabral, Henrique

    2008-08-01

    Connectivity is a critical property of marine populations, particularly for species with segregated juvenile and adult habitats. Knowledge of this link is fundamental in understanding population structure and dynamics. Young adults of commercially important fish species Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax were sampled off the Portuguese coast in order to establish preliminary evidence of estuarine nursery origins through otolith elemental fingerprints. Concentrations of Li, Na, Mg, K, Mn, Cu, Zn, Sr, Ba and Pb in the otolith section corresponding to juvenile's nursery life period were determined through laser ablation inductively coupled plasma mass spectrometry. Element: Ca ratios in coastal fish differed significantly amongst collection areas, except for Platichthys flesus, and were compared with the elemental fingerprints previously defined for age 0 juveniles in the main estuarine nurseries of the Portuguese coast. Identification of nursery estuaries was achieved for four of the species. Assigned nursery origins varied amongst species and differences in the spatial scale of fish dispersal were also found. Diplodus vulgaris was not reliably assigned to any of the defined nurseries. Overall, results give evidence of the applicability of estuarine habitat tags in future assessments of estuarine nursery role. Research developments on the links between juvenile and adult habitats should contribute for the integrated management and conservation of nurseries and coastal stocks.

  15. Eating fish for two

    PubMed Central

    Strain, JJ

    2014-01-01

    Summary This article is based on the British Nutrition Foundation’s Annual Lecture, which focused on maternal fish consumption and the effects of methylmercury (MeHg) on fetal development, with respect to current guidance and policy on fish consumption during pregnancy. Fish makes a valuable contribution to nutrient intakes across the globe and is the primary protein source for many individuals, particularly those in the developing world. Populations with a high fish consumption, such as in the Republic of the Seychelles, have a greater exposure to MeHg, which is present in varying amounts in all fish. Methylmercury is a toxic pollutant, which is known to impair neurodevelopment. The dose of MeHg from fish consumption, however, needed to impair neurodevelopment is unknown. Current UK and US guidance on fish consumption during pregnancy tend to focus more on avoiding risks rather than highlighting the benefits which can be obtained from eating fish. Such recommendations have been mainly based on data arising from epidemiological studies in the Faroe Islands, where methylmercury exposure was largely from pilot whale consumption. Although small adverse effects on child development have been reported in data from the Faroe Islands, data from the on-going Seychelles Child Development Studies have shown no adverse effects of prenatal methlymercury exposure from high maternal fish consumption (9–12 meals containing fish per week) on developmental outcomes. Instead these data suggest that nutrients, including long chain polyunsaturated fatty acids (LC-PUFAs), provided by fish may offer a beneficial effect and attenuate or modify any effects of MeHg on developmental outcomes. Recent expert consultations have concluded that the health benefits of fish consumption outweigh the risks posed by MeHg exposure and have argued the need for improved education and guidance to highlight the importance of consuming nutrients, including LC-PUFAs, from fish for optimal child

  16. Effects of acclimation on poststocking dispersal and physiological condition of age-1 pallid sturgeon

    USGS Publications Warehouse

    Oldenburg, E.W.; Guy, C.S.; Cureton, E.S.; Webb, M.A.H.; Gardner, W.M.

    2011-01-01

    The objective of this study was to evaluate the effects of acclimation to flow and site-specific physicochemical water conditions on poststocking dispersal and physiological condition of age-1 hatchery-reared pallid sturgeon. Fish from three acclimation treatments were radio-tagged, released at two locations (Missouri River and Marias River), and monitored using passive telemetry stations. Marias treatment was acclimated to flow and site-specific physicochemical conditions, Bozeman treatment was acclimated to flow only, and controls had no acclimation (reared under traditional conservation propagation protocol). During both years, fish released in the Missouri River dispersed less than fish released in the Marias River. In 2005, Marias treatment dispersed less and nearly twice as many fish remained in the Missouri River reach as compared to control fish. In 2006, pallid sturgeon dispersed similarly among treatments and the number of fish remaining in the Missouri River reach was similar among all treatments. Differences in poststocking dispersal between years were related to fin curl which was present in all fish in 2005 and only 26% in 2006. Pallid sturgeon from all treatments in both years had a greater affinity for the lower reaches of the Missouri River than the upper reaches. Thus, release site influenced poststocking dispersal more than acclimation treatment. No difference was observed in relative growth rate among treatments. However, acclimation to flow (i.e., exercise conditioning) prevented fat accumulation from rupturing hepatocytes. Acclimation conditions used in this study did not benefit pallid sturgeon unless physiological maladies were present. Overriding all treatment effects was stocking location; thus, natural resource agencies need to consider stocking location carefully to reduce poststocking dispersal. ?? 2011 Blackwell Verlag, Berlin.

  17. Ascent of neotropical migratory fish in the Itaipu Reservoir fish pass

    USGS Publications Warehouse

    Makrakis, S.; Miranda, L.E.; Gomes, L.C.; Makrakis, M.C.; Junior, H.M.F.

    2011-01-01

    The Piracema Canal is a complex 10-km fish pass system that climbs 120m to connect the Paran?? River to the Itaipu Reservoir along the Brazil-Paraguay border. The canal was constructed to allow migratory fishes to reach suitable habitats for reproduction and feeding in tributaries upstream from the reservoir. The Piracema Canal attracted 17 of the 19 long-distance migratory species that have been recorded in the Paran?? River Basin and Paraguay-Paran?? Basin. However, the incidence of migratory fish decreased from downstream to upstream, with the pattern of decrease depending on species. Overall, 0.5% of the migratory fish that entered the Piracema Canal and segment 1, eventually were able to reach segment 5 and potentially Itaipu Reservoir. Ascension rate was examined relative to various physical attributes of canal segments; maximum water velocity emerged as the most influential variable affecting fish passage. Water velocity may be manipulated by controlling water discharge, and by re-engineering critical sections of the canal. Because the Itaipu Reservoir flooded a set of falls that separated two distinct biogeographical regions, facilitating fish movements through the Piracema Canal into the Itaipu Reservoir presents a management dilemma that requires deliberation in the context of the fish assemblages rather than on selected migratory species. ?? 2010 John Wiley & Sons, Ltd.

  18. When is dispersal for dispersal? Unifying marine and terrestrial perspectives.

    PubMed

    Burgess, Scott C; Baskett, Marissa L; Grosberg, Richard K; Morgan, Steven G; Strathmann, Richard R

    2016-08-01

    Recent syntheses on the evolutionary causes of dispersal have focused on dispersal as a direct adaptation, but many traits that influence dispersal have other functions, raising the question: when is dispersal 'for' dispersal? We review and critically evaluate the ecological causes of selection on traits that give rise to dispersal in marine and terrestrial organisms. In the sea, passive dispersal is relatively easy and specific morphological, behavioural, and physiological adaptations for dispersal are rare. Instead, there may often be selection to limit dispersal. On land, dispersal is relatively difficult without specific adaptations, which are relatively common. Although selection for dispersal is expected in both systems and traits leading to dispersal are often linked to fitness, systems may differ in the extent to which dispersal in nature arises from direct selection for dispersal or as a by-product of selection on traits with other functions. Our analysis highlights incompleteness of theories that assume a simple and direct relationship between dispersal and fitness, not just insofar as they ignore a vast array of taxa in the marine realm, but also because they may be missing critically important effects of traits influencing dispersal in all realms. PMID:26118564

  19. Structural habitat predicts functional dispersal habitat of a large carnivore: how leopards change spots.

    PubMed

    Fattebert, Julien; Robinson, Hugh S; Balme, Guy; Slotow, Rob; Hunter, Luke

    2015-10-01

    Natal dispersal promotes inter-population linkage, and is key to spatial distribution of populations. Degradation of suitable landscape structures beyond the specific threshold of an individual's ability to disperse can therefore lead to disruption of functional landscape connectivity and impact metapopulation function. Because it ignores behavioral responses of individuals, structural connectivity is easier to assess than functional connectivity and is often used as a surrogate for landscape connectivity modeling. However using structural resource selection models as surrogate for modeling functional connectivity through dispersal could be erroneous. We tested how well a second-order resource selection function (RSF) models (structural connectivity), based on GPS telemetry data from resident adult leopard (Panthera pardus L.), could predict subadult habitat use during dispersal (functional connectivity). We created eight non-exclusive subsets of the subadult data based on differing definitions of dispersal to assess the predictive ability of our adult-based RSF model extrapolated over a broader landscape. Dispersing leopards used habitats in accordance with adult selection patterns, regardless of the definition of dispersal considered. We demonstrate that, for a wide-ranging apex carnivore, functional connectivity through natal dispersal corresponds to structural connectivity as modeled by a second-order RSF. Mapping of the adult-based habitat classes provides direct visualization of the potential linkages between populations, without the need to model paths between a priori starting and destination points. The use of such landscape scale RSFs may provide insight into predicting suitable dispersal habitat peninsulas in human-dominated landscapes where mitigation of human-wildlife conflict should be focused. We recommend the use of second-order RSFs for landscape conservation planning and propose a similar approach to the conservation of other wide-ranging large

  20. Dispersal of Symbiodinium by the stoplight parrotfish Sparisoma viride

    PubMed Central

    Castro-Sanguino, Carolina; Sánchez, Juan A.

    2012-01-01

    Environmental reservoirs of zooxanthellae are essential for coral larvae settlement; understanding where they occur and how they are maintained is important for coral reef ecology. This study investigated the dispersal of Symbiodinium spp. by the stoplight parrotfish Sparisoma viride, which had high mean densities of viable and cultivable Symbiodinium (3207–8900 cells ml−1) in faeces. Clades A, B and G were detected using amplified chloroplast ribosomal sequences (cp23S-HVR), and corresponded with diet preferences of fish and the environmental Symbiodinium diversity of the region. Cells are constantly dispersed in the water column and deposited in the substrate at a local level (86 ± 17.8 m2), demonstrating that parrotfishes are vectors for short-distance dispersal of zooxanthellae. Such dispersal could constitute a key role in the maintenance of environmental Symbiodinium reservoirs. PMID:21957090

  1. Cauchy's dispersion equation reconsidered : dispersion in silicate glasses.

    SciTech Connect

    Smith, D. Y.; Inokuti, M.; Karstens, W.; Physics; Univ. of Vermont; St. Michael's College

    2002-01-01

    We formulate a novel method of characterizing optically transparent substances using dispersion theory. The refractive index is given by a generalized Cauchy dispersion equation with coefficients that are moments of the uv and ir absorptions. Mean dispersion, Abbe number, and partial dispersion are combinations of these moments. The empirical relation between index and dispersion for families of glasses appears as a consequence of Beer's law applied to the uv spectra.

  2. KISMET tungsten dispersal experiment

    SciTech Connect

    Wohletz, K.; Kunkle, T.; Hawkins, W.

    1996-12-01

    Results of the KISMET tungsten dispersal experiment indicate a relatively small degree of wall-rock contamination caused by this underground explosive experiment. Designed as an add-on to the KISMET test, which was performed in the U-1a.02 drift of the LYNER facility at Nevada Test Site on 1 March 1995, this experiment involved recovery and analysis of wall-rock samples affected by the high- explosive test. The chemical, high-explosive blast drove tungsten powder, placed around the test package as a plutonium analog, into the surrounding wall- rock alluvium. Sample analyses by an analytical digital electron microscope (ADEM) show tungsten dispersed in the rock as tiny (<10 {mu}m) particles, agglomerates, and coatings on alluvial clasts. Tungsten concentrations, measured by energy dispersive spectral analysis on the ADEM, indicate penetration depths less than 0.1 m and maximum concentrations of 1.5 wt % in the alluvium.

  3. Fog dispersal technology.

    NASA Technical Reports Server (NTRS)

    Mcgowan, W. A.

    1971-01-01

    The state-of-the-art in fog dispersal technology is briefly discussed. Fog is categorized as supercooled fog, occurring in air temperatures below freezing, and warm fog, occurring at above-freezing temperatures. Operational techniques are available to disperse supercooled fog in the airport area. It is much more difficult to cope with warm fog. Various known concepts to disperse warm fog are evaluated as to their operational merits. The most effective concept for immediate use involves heating the air to cause fog evaporation. Use of helicopter downwash has some application, possibly complementing the promising concept of seeding with sized hygroscopic particles. These latter two concepts appear to have future application, pending further research. The concept using polyelectrolytes is of uncertain value, lacking both a scientific explanation and a substantive evaluation of reported operational successes.

  4. Drilling mud dispersants

    SciTech Connect

    Gleason, P. A.; Brase, I. E.

    1985-05-21

    Dispersants useful in aqueous drilling mud formulations employed in the drilling of subterranean wells where high temperature and high pressure environments are encountered are disclosed. The dispersants, when used in amounts of about 0.1 to 25 ppb provide muds containing colloidal material suspended in an aqueous medium with improved high temperature and high pressure stability. The dispersants are water soluble sulfonated vinyl toluene-maleic anhydride copolymers which have a molar ratio of vinyl toluene to maleic anhydride of about 1:1 to less than about 2:1, a molecular weight of 1,000 to 25,000 and at least about 0.7 sulfonic acid groups per vinyl toluene unit.

  5. Fish scales as indicators of wastewater toxicity from an international water channel Tung Dhab drain.

    PubMed

    Kaur, Rajbir; Dua, Anish

    2012-05-01

    The effect of wastewater exposure on scales and chromatophores of freshwater fish Channa punctatus was studied using wastewater dilutions (60-100%) from an international water channel Tung Dhab drain at an interval of 15 and 30 days. The exposed fish showed significant alterations such as uprooted and damaged lepidonts and dispersal of chromatophores. These observations strongly suggest that fish scales can be successfully employed as indicators of wastewater pollution. PMID:21701892

  6. Passage order through different pathways in groups of schooling fish, and the diversified leadership hypothesis.

    PubMed

    Levin, L E

    1996-08-01

    The diversified leadership hypothesis proposes that different individuals within a school of fish act as leaders in different circumstances. This 'circumstantial leadership' results from inter-individual behavioral variability and a 'cohesion-dispersion' tendency modulated by 'failure-success' contingencies. The hypothesis predicts that when offered different pathways to escape the restriction of their swimming space, individuals within a group of fish will show Using an avoidance paddle and three different groups of fish (Aphyocharax erithrurus) the results confirmed prediction. PMID:24897153

  7. Fragmentation alters stream fish community structure in dendritic ecological networks.

    PubMed

    Perkin, Joshuah S; Gido, Keith B

    2012-12-01

    Effects of fragmentation on the ecology of organisms occupying dendritic ecological networks (DENs) have recently been described through both conceptual and mathematical models, but few hypotheses have been tested in complex, real-world ecosystems. Stream fishes provide a model system for assessing effects of fragmentation on the structure of communities occurring within DENs, including how fragmentation alters metacommunity dynamics and biodiversity. A recently developed habitat-availability measure, the "dendritic connectivity index" (DCI), allows for assigning quantitative measures of connectivity in DENs regardless of network extent or complexity, and might be used to predict fish community response to fragmentation. We characterized stream fish community structure in 12 DENs in the Great Plains, USA, during periods of dynamic (summer) and muted (fall) discharge regimes to test the DCI as a predictive model of fish community response to fragmentation imposed by road crossings. Results indicated that fish communities in stream segments isolated by road crossings had reduced species richness (alpha diversity) relative to communities that maintained connectivity with the surrounding DEN during summer and fall. Furthermore, isolated communities had greater dissimilarity (beta diversity) to downstream sites notisolated by road crossings during summer and fall. Finally, dissimilarity among communities within DENs decreased as a function of increased habitat connectivity (measured using the DCI) for summer and fall, suggesting that communities within highly connected DENs tend to be more homogeneous. Our results indicate that the DCI is sensitive to community effects of fragmentation in riverscapes and might be used by managers to predict ecological responses to changes in habitat connectivity. Moreover, our findings illustrate that relating structural connectivity of riverscapes to functional connectivity among communities might aid in maintaining metacommunity

  8. Multiscale analysis of compartment models with dispersal

    PubMed Central

    Kang, Yun; Castillo-Chavez, Carlos

    2014-01-01

    Dispersal, minimally defined as the movement or spatial displacement of organisms, links the dynamics of local population within and across regions. Landscape-population interactions responsible for driving co-evolutionary processes that on the long run shape communities of organisms, determine the outcomes of biological invasions, or alter the dynamics and evolution of infectious agents, are connected via dispersal. A generalized modeling framework is introduced derived from our interests in characterizing the dynamics of animal populations and trade in the presence of disease. We explore the impact of dispersal on systems that include disease, Allee effects, and host mobility. The emphasis is on disease, a selective force, that often plays a fundamental role on the life-history dynamics of a population. The models incorporate disease-driven effects on, often excluded, interactions like individual’s competitive ability to acquire resources. The framework makes use of deterministic and stochastic models that account for features often ignored or rarely included like (a) induced Allee effects; (b) disease dynamics; and (c) spatial heterogeneity. Preliminary results highlight the role of initial conditions, patch quality, and “topological” or connectivity landscape structure (the physical space where individuals move, reproduce, get sick, die, or compete for resources) on the dynamics of populations when disease is an important selective force. We dedicate this article to our grand mentor Simon Levin. PMID:22934939

  9. About measuring velocity dispersions

    NASA Astrophysics Data System (ADS)

    Fellhauer, M.

    A lot of our knowledge about the dynamics and total masses of pressure dominated stellar systems relies on measuring the internal velocity disper- sion of the system. We assume virial equilibrium and that we are able to measure only the bound stars of the system without any contamination. This article shows how likely it is to measure the correct velocity dispersion in reality. It will show that as long as we have small samples of velocity mea- surements the distribution of possible outcomes can be very large and as soon as we have a source of error the velocity dispersion can wrong by several standard deviations especially in large samples.

  10. Uranium Dispersion & Dosimetry Model.

    SciTech Connect

    MICHAEL,; MOMENI, H.

    2002-03-22

    The Uranium Dispersion and Dosimetry (UDAD) program provides estimates of potential radiation exposure to individuals and to the general population in the vicinity of a uranium processing facility such as a uranium mine or mill. Only transport through the air is considered. Exposure results from inhalation, external irradiation from airborne and ground-deposited activity, and ingestion of foodstuffs. Individual dose commitments, population dose commitments, and environmental dose commitments are computed. The program was developed for application to uranium mining and milling; however, it may be applied to dispersion of any other pollutant.

  11. Uranium Dispersion & Dosimetry Model.

    Energy Science and Technology Software Center (ESTSC)

    2002-03-22

    The Uranium Dispersion and Dosimetry (UDAD) program provides estimates of potential radiation exposure to individuals and to the general population in the vicinity of a uranium processing facility such as a uranium mine or mill. Only transport through the air is considered. Exposure results from inhalation, external irradiation from airborne and ground-deposited activity, and ingestion of foodstuffs. Individual dose commitments, population dose commitments, and environmental dose commitments are computed. The program was developed for applicationmore » to uranium mining and milling; however, it may be applied to dispersion of any other pollutant.« less

  12. Pollen clumping and wind dispersal in an invasive angiosperm.

    PubMed

    Martin, Michael D; Chamecki, Marcelo; Brush, Grace S; Meneveau, Charles; Parlange, Marc B

    2009-09-01

    Pollen dispersal is a fundamental aspect of plant reproductive biology that maintains connectivity between spatially separated populations. Pollen clumping, a characteristic feature of insect-pollinated plants, is generally assumed to be a detriment to wind pollination because clumps disperse shorter distances than do solitary pollen grains. Yet pollen clumps have been observed in dispersion studies of some widely distributed wind-pollinated species. We used Ambrosia artemisiifolia (common ragweed; Asteraceae), a successful invasive angiosperm, to investigate the effect of clumping on wind dispersal of pollen under natural conditions in a large field. Results of simultaneous measurements of clump size both in pollen shedding from male flowers and airborne pollen being dispersed in the atmosphere are combined with a transport model to show that rather than being detrimental, clumps may actually be advantageous for wind pollination. Initial clumps can pollinate the parent population, while smaller clumps that arise from breakup of larger clumps can cross-pollinate distant populations. PMID:21622356

  13. Immunostimulants in fish diets

    USGS Publications Warehouse

    Gannam, A.L.; Schrock, R.M.

    1999-01-01

    Various immunostimulants and their methods of application in fish culture are examined in this review. Important variables such as life stage and innate disease resistance of the fish; immunostimulant used, its structure and mode of action; and the fish's environment are discussed. Conflicting results have been published about the efficacy of immunostimulants in fish diets. Some researchers have had positive responses demonstrated as increased fish survival, others have not. Generally, immunostimulants enhance individual components of the non-specific immune response but that does not always translate into increased fish survival. In addition, immunostimulants fed at too high a dose or for too long can be immunosuppressive. [Article copies available for a fee from The Haworth Document Delivery Service: 1-800-342-9678. E-mail address: getinfo@haworthpressinc.com ].

  14. Fish as Reservoirs and Vectors of Vibrio cholerae

    PubMed Central

    Senderovich, Yigal; Izhaki, Ido; Halpern, Malka

    2010-01-01

    Vibrio cholerae, the etiologic agent of cholera, is autochthonous to various aquatic environments, but despite intensive efforts its ecology remains an enigma. Recently, it was suggested that copepods and chironomids, both considered as natural reservoirs of V. cholerae, are dispersed by migratory waterbirds, thus possibly distributing the bacteria between water bodies within and between continents. Although fish have been implicated in the scientific literature with cholera cases, as far as we know, no study actually surveyed the presence of the bacteria in the fish. Here we show for the first time that fish of various species and habitats contain V. cholerae in their digestive tract. Fish (n = 110) were randomly sampled from freshwater and marine habitats in Israel. Ten different fish species sampled from freshwater habitats (lake, rivers and fish ponds), and one marine species, were found to carry V. cholerae. The fish intestine of Sarotherodon galilaeus harboured ca. 5×103 V. cholerae cfu per 1 gr intestine content—high rates compared with known V. cholerae cfu numbers in the bacteria's natural reservoirs. Our results, combined with evidence from the literature, suggest that fish are reservoirs of V. cholerae. As fish carrying the bacteria swim from one location to another (some fish species move from rivers to lakes or sea and vice versa), they serve as vectors on a small scale. Nevertheless, fish are consumed by waterbirds, which disseminate the bacteria on a global scale. Moreover, V. cholerae isolates had the ability to degrade chitin, indicating a commensal relationship between V. cholerae and fish. Better understanding of V. cholerae ecology can help reduce the times that human beings come into contact with this pathogen and thus minimize the health risk this poses. PMID:20066040

  15. The FDA's new advice on fish: it's complicated.

    PubMed

    Wenstrom, Katharine D

    2014-11-01

    The Food and Drug Administration and Environmental Protection Agency recently issued an updated draft of advice on fish consumption for pregnant and breastfeeding women, after survey data indicated that the majority of pregnant women do not eat much fish and thus may have inadequate intake of the omega 3 fatty acids eicosapentaenoic acid [EPA] and ducosahexaenoic acid [DHA]. Omega 3 fatty acids are essential components of membranes in all cells of the body and are vitally important for normal development of the brain and retinal tissues (especially myelin and retinal photoreceptors) and for maintenance of normal neurotransmission and connectivity. They also serve as substrates for the synthesis of a variety of antiinflammatory and inflammation-resolving mediators, favorably alter the production of thromboxane and prostaglandin E2, and improve cardiovascular health by preventing fatal arrhythmias and reducing triglyceride and C-reactive protein levels. Maternal ingestion of adequate quantities of fish (defined in many studies as at least 340 g of oily fish each week) has been associated with better childhood IQ scores, fine motor coordination, and communication and social skills, along with other benefits. Although the FDA did not clarify which fish to eat, it specifically advised against eating fish with the highest mercury levels and implied that fish with high levels of EPA and DHA and low levels of mercury are ideal. The FDA draft did not recommend taking omega 3 fatty acid or fish oil supplements instead of eating fish, which is advice that may reflect the fact that randomized controlled trials of DHA and EPA or fish oil supplementation generally have been disappointing and that the ideal daily dose of DHA and EPA is unknown. It seems safe to conclude that pregnant and nursing women should be advised to eat fish to benefit from naturally occurring omega 3 fatty acids, to avoid fish with high levels of mercury and other contaminants, and, if possible, to choose

  16. Mangroves Enhance Reef Fish Abundance at the Caribbean Regional Scale

    PubMed Central

    Serafy, Joseph E.; Shideler, Geoffrey S.; Araújo, Rafael J.; Nagelkerken, Ivan

    2015-01-01

    Several studies conducted at the scale of islands, or small sections of continental coastlines, have suggested that mangrove habitats serve to enhance fish abundances on coral reefs, mainly by providing nursery grounds for several ontogenetically-migrating species. However, evidence of such enhancement at a regional scale has not been reported, and recently, some researchers have questioned the mangrove-reef subsidy effect. In the present study, using two different regression approaches, we pursued two questions related to mangrove-reef connectivity at the Caribbean regional scale: (1) Are reef fish abundances limited by mangrove forest area?; and (2) Are mean reef fish abundances proportional to mangrove forest area after taking human population density and latitude into account? Specifically, we tested for Caribbean-wide mangrove forest area effects on the abundances of 12 reef fishes that have been previously characterized as “mangrove-dependent”. Analyzed were data from an ongoing, long-term (20-year) citizen-scientist fish monitoring program; coastal human population censuses; and several wetland forest information sources. Quantile regression results supported the notion that mangrove forest area limits the abundance of eight of the 12 fishes examined. Linear mixed-effects regression results, which considered potential human (fishing and habitat degradation) and latitudinal influences, suggested that average reef fish densities of at least six of the 12 focal fishes were directly proportional to mangrove forest area. Recent work questioning the mangrove-reef fish subsidy effect likely reflects a failure to: (1) focus analyses on species that use mangroves as nurseries, (2) consider more than the mean fish abundance response to mangrove forest extent; and/or (3) quantitatively account for potentially confounding human impacts, such as fishing pressure and habitat degradation. Our study is the first to demonstrate at a large regional scale (i.e., the Wider

  17. Endangered river fish: factors hindering conservation and restoration

    USGS Publications Warehouse

    Cooke, Steven J.; Paukert, Craig P.; Hogan, Zeb

    2012-01-01

    Globally, riverine fish face many anthropogenic threats including riparian and flood plain habitat degradation, altered hydrology, migration barriers, fisheries exploitation, environmental (climate) change, and introduction of invasive species. Collectively, these threats have made riverine fishes some of the most threatened taxa on the planet. Although much effort has been devoted to identifying the threats faced by river fish, there has been less effort devoted to identifying the factors that may hinder our ability to conserve and restore river fish populations and their watersheds. Therefore, we focus our efforts on identifying and discussing 10 general factors (can also be viewed as research and implementation needs) that constrain or hinder effective conservation action for endangered river fish: (1) limited basic natural history information; (2) limited appreciation for the scale/extent of migrations and the level of connectivity needed to sustain populations; (3) limited understanding of fish/river-flow relationships; (4) limited understanding of the seasonal aspects of river fish biology, particularly during winter and/or wet seasons; (5) challenges in predicting the response of river fish and river ecosystems to both environmental change and various restoration or management actions; (6) limited understanding of the ecosystem services provided by river fish; (7) the inherent difficulty in studying river fish; (8) limited understanding of the human dimension of river fish conservation and management; (9) limitations of single species approaches that often fail to address the broader-scale problems; and (10) limited effectiveness of governance structures that address endangered river fish populations and rivers that cross multiple jurisdictions. We suggest that these issues may need to be addressed to help protect, restore, or conserve river fish globally, particularly those that are endangered.

  18. Mangroves Enhance Reef Fish Abundance at the Caribbean Regional Scale.

    PubMed

    Serafy, Joseph E; Shideler, Geoffrey S; Araújo, Rafael J; Nagelkerken, Ivan

    2015-01-01

    Several studies conducted at the scale of islands, or small sections of continental coastlines, have suggested that mangrove habitats serve to enhance fish abundances on coral reefs, mainly by providing nursery grounds for several ontogenetically-migrating species. However, evidence of such enhancement at a regional scale has not been reported, and recently, some researchers have questioned the mangrove-reef subsidy effect. In the present study, using two different regression approaches, we pursued two questions related to mangrove-reef connectivity at the Caribbean regional scale: (1) Are reef fish abundances limited by mangrove forest area?; and (2) Are mean reef fish abundances proportional to mangrove forest area after taking human population density and latitude into account? Specifically, we tested for Caribbean-wide mangrove forest area effects on the abundances of 12 reef fishes that have been previously characterized as "mangrove-dependent". Analyzed were data from an ongoing, long-term (20-year) citizen-scientist fish monitoring program; coastal human population censuses; and several wetland forest information sources. Quantile regression results supported the notion that mangrove forest area limits the abundance of eight of the 12 fishes examined. Linear mixed-effects regression results, which considered potential human (fishing and habitat degradation) and latitudinal influences, suggested that average reef fish densities of at least six of the 12 focal fishes were directly proportional to mangrove forest area. Recent work questioning the mangrove-reef fish subsidy effect likely reflects a failure to: (1) focus analyses on species that use mangroves as nurseries, (2) consider more than the mean fish abundance response to mangrove forest extent; and/or (3) quantitatively account for potentially confounding human impacts, such as fishing pressure and habitat degradation. Our study is the first to demonstrate at a large regional scale (i.e., the Wider

  19. Fish and wildlife surveillance

    SciTech Connect

    Poston, T.M.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the monitoring of radioactive contaminants in fish and wildlife species that inhabit the Colombia River and Hanford Site. Wildlife have access to areas of the Site containing radioactive contamination, and fish can be exposed to contamination in spring water entering the river along the shoreline. Therefore, samples are collected at various locations annually, generally during the hunting or fishing season, for selected species.

  20. Differences in Time until Dispersal between Cryptic Species of a Marine Nematode Species Complex

    PubMed Central

    De Meester, Nele; Derycke, Sofie; Moens, Tom

    2012-01-01

    Co-occurrence of closely related species may be achieved in environments with fluctuating dynamics, where competitively inferior species can avoid competition through dispersal. Here we present an experiment in which we compared active dispersal abilities (time until first dispersal, number and gender of dispersive adults, and nematode densities at time of dispersal) in Litoditis marina, a common bacterivorous nematode species complex comprising four often co-occurring cryptic species, Pm I, II, III, and IV, as a function of salinity and food distribution. The experiment was conducted in microcosms consisting of an inoculation plate, connection tube, and dispersal plate. Results show species-specific dispersal abilities with Pm I dispersing almost one week later than Pm III. The number of dispersive adults at time of first dispersal was species-specific, with one dispersive female in Pm I and Pm III and a higher, gender-balanced, number in Pm II and Pm IV. Food distribution affected dispersal: in absence of food in the inoculation plate, all species dispersed after ca four days. When food was available Pm I dispersed later, and at the same time and densities irrespective of food conditions in the dispersal plate (food vs no food), suggesting density-dependent dispersal. Pm III dispersed faster and at a lower population density. Salinity affected dispersal, with slower dispersal at higher salinity. These results suggest that active dispersal in Litoditis marina is common, density-dependent, and with species, gender- and environment-specific dispersal abilities. These differences can lead to differential responses under suboptimal conditions and may help to explain temporary coexistence at local scales. PMID:22876328

  1. Warm fog dispersal

    NASA Technical Reports Server (NTRS)

    Frost, W.

    1983-01-01

    The charged particle generator was further tested after some design modification. The generator performance was measured with additional instrumentation and found to confirm previous measurements. Plans for a field testing were than developed. The overall status of the program and the field test plans were presented to a group of atmospheric scientists and electrostatic experts at the NASA/MSFC sponsored USRA Workshop on Electrostatic Fog Dispersal at NCAR, Boulder, Colorado discussed in previous sections. The recommendations from this workshop are being evaluated as to whether NASA should proceed with the field test or whether further theoretical research on the phenomenon of electrostatic fog dispersal and additional development of the charged particle generator should be carried out. Information obtained from the USRA Workshop clearly identified three physical mechanisms that could possibly influence the fog dispersal process, which heretofore have not been considered, and which may provide additional insight to the direction of further fog dispersal work. These mechanisms are: the effect of corona discharge on the electric field strength at the surface, the influx of fog into the cleared volume by turbulent diffusion, and the increase in supersaturation as liquid water is removed, activating haze particles, and thus generating more fog. Plans are being formulated to investigate these mechanisms.

  2. Acoustic dispersive prism.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  3. Acoustic dispersive prism

    PubMed Central

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz–1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  4. Acoustic dispersive prism

    NASA Astrophysics Data System (ADS)

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.

  5. From Shelf to Shelf: Assessing Historical and Contemporary Genetic Differentiation and Connectivity across the Gulf of Mexico in Gag, Mycteroperca microlepis

    PubMed Central

    Jue, Nathaniel K.; Brulé, Thierry; Coleman, Felicia C.; Koenig, Christopher C.

    2015-01-01

    Describing patterns of connectivity among populations of species with widespread distributions is particularly important in understanding the ecology and evolution of marine species. In this study, we examined patterns of population differentiation, migration, and historical population dynamics using microsatellite and mitochondrial loci to test whether populations of the epinephelid fish, Gag, Mycteroperca microlepis, an important fishery species, are genetically connected across the Gulf of Mexico and if so, whether that connectivity is attributable to either contemporary or historical processes. Populations of Gag on the Campeche Bank and the West Florida Shelf show significant, but low magnitude, differentiation. Time since divergence/expansion estimates associated with historical population dynamics indicate that any population or spatial expansions indicated by population genetics would have likely occurred in the late Pleistocene. Using coalescent-based approaches, we find that the best model for explaining observed spatial patterns of contemporary genetic variation is one of asymmetric gene flow, with movement from Campeche Bank to the West Florida Shelf. Both estimated migration rates and ecological data support the hypothesis that Gag populations throughout the Gulf of Mexico are connected via present day larval dispersal. Demonstrating this greatly expanded scale of connectivity for Gag highlights the influence of “ghost” populations (sensu Beerli) on genetic patterns and presents a critical consideration for both fisheries management and conservation of this and other species with similar genetic patterns. PMID:25856095

  6. The influence of spawning periodicity on population connectivity

    NASA Astrophysics Data System (ADS)

    Kough, Andrew S.; Paris, Claire B.

    2015-09-01

    Many coral reef populations exist as discrete habitat patches linked through larval dispersal into a larger network. On these reefs, organisms spawn periodically and release propagules over a range of frequencies. Biophysical models of larval transport examine marine networks, yet particle release frequency needs careful consideration. We describe the time between sequential spawning events as the release interval and define any linkage of modeled larvae between two habitat sites as a connection. We investigate how changing the release interval affects the connectivity networks of three Caribbean species with low- to high-dispersal potential and swimming behavior. We find that spawning periodicity controls the number and persistence of network connections. Further, larval vertical movement behavior stabilizes the network, significantly increasing connections and connection persistence. This work demonstrates the impact of release interval on connectivity networks and underscores including larval behavior with realistic spawning periodicity in biophysical models of larval transport.

  7. Octave spanning wedge dispersive mirrors with low dispersion oscillations.

    PubMed

    Habel, Florian; Shirvanyan, Vage; Trubetskov, Michael; Burger, Christian; Sommer, Annkatrin; Kling, Matthias F; Schultze, Martin; Pervak, Vladimir

    2016-05-01

    A novel concept for octave spanning dispersive mirrors with low spectral dispersion oscillations is presented. The key element of the so-called wedge dispersive mirror is a slightly wedged layer which is coated on a specially optimized dispersive multilayer stack by a common sputter coating process. The group delay dispersion (GDD) of a pulse reflected on a wedge dispersive mirror is nearly free of oscillations. Fabricated mirrors with negative GDD demonstrate the compression of a pulse down to 3.8 fs as good as double angled mirrors optimized for the same bandwidth. PMID:27137538

  8. Fish-allergic patients may be able to eat fish.

    PubMed

    Mourad, Ahmad A; Bahna, Sami L

    2015-03-01

    Reported fish allergy prevalence varies widely, with an estimated prevalence of 0.2% in the general population. Sensitization to fish can occur by ingestion, skin contact or inhalation. The manifestations can be IgE or non-IgE mediated. Several fish allergens have been identified, with parvalbumins being the major allergen in various species. Allergenicity varies among fish species and is affected by processing or preparation methods. Adverse reactions after eating fish are often claimed to be 'allergy' but could be a reaction to hidden food allergen, fish parasite, fish toxins or histamine in spoiled fish. Identifying such causes would allow free consumption of fish. Correct diagnosis of fish allergy, including the specific species, might provide the patient with safe alternatives. Patients have been generally advised for strict universal avoidance of fish. However, testing with various fish species or preparations might identify one or more forms that can be tolerated. PMID:25666551

  9. Dispersed oil disrupts microbial pathways in pelagic food webs.

    PubMed

    Ortmann, Alice C; Anders, Jennifer; Shelton, Naomi; Gong, Limin; Moss, Anthony G; Condon, Robert H

    2012-01-01

    Most of the studies of microbial processes in response to the Deepwater Horizon oil spill focused on the deep water plume, and not on the surface communities. The effects of the crude oil and the application of dispersants on the coastal microbial food web in the northern Gulf of Mexico have not been well characterized even though these regions support much of the fisheries production in the Gulf. A mesocosm experiment was carried out to determine how the microbial community off the coast of Alabama may have responded to the influx of surface oil and dispersants. While the addition of glucose or oil alone resulted in an increase in the biomass of ciliates, suggesting transfer of carbon to higher trophic levels was likely; a different effect was seen in the presence of dispersant. The addition of dispersant or dispersed oil resulted in an increase in the biomass of heterotrophic prokaryotes, but a significant inhibition of ciliates, suggesting a reduction in grazing and decrease in transfer of carbon to higher trophic levels. Similar patterns were observed in two separate experiments with different starting nutrient regimes and microbial communities suggesting that the addition of dispersant and dispersed oil to the northern Gulf of Mexico waters in 2010 may have reduced the flow of carbon to higher trophic levels, leading to a decrease in the production of zooplankton and fish on the Alabama shelf. PMID:22860136

  10. Functional nasal morphology of chimaerid fishes.

    PubMed

    Howard, Lauren E; Holmes, William M; Ferrando, Sara; Maclaine, James S; Kelsh, Robert N; Ramsey, Andrew; Abel, Richard L; Cox, Jonathan P L

    2013-09-01

    Holocephalans (chimaeras) are a group of marine fishes comprising three families: the Callorhinchidae (callorhinchid fishes), the Rhinochimaeridae (rhinochimaerid fishes) and the Chimaeridae (chimaerid fishes). We have used X-ray microcomputed tomography and magnetic resonance imaging to characterise in detail the nasal anatomy of three species of chimaerid fishes: Chimaera monstrosa, C. phantasma and Hydrolagus colliei. We have shown that the nasal chamber of these three species is linked to the external environment by an incurrent channel and to the oral cavity by an excurrent channel via an oral groove. A protrusion of variable morphology is present on the medial wall of the incurrent channel in all three species, but is absent in members of the two other holocephalan families that we inspected. A third nasal channel, the lateral channel, functionally connects the incurrent nostril to the oral cavity, by-passing the nasal chamber. From anatomical reconstructions, we have proposed a model for the circulation of water, and therefore the transport of odorant, in the chimaerid nasal region. In this model, water could flow through the nasal region via the nasal chamber or the lateral channel. In either case, the direction of flow could be reversed. Circulation through the entire nasal region is likely to be driven primarily by the respiratory pump. We have identified several anatomical features that may segregate, distribute, facilitate and regulate flow in the nasal region and have considered the consequences of flow reversal. The non-sensory cilia lining the olfactory sensory channels appear to be mucus-propelling, suggesting that these cilia have a common protective role in cartilaginous fishes (sharks, rays and chimaeras). The nasal region of chimaerid fishes shows at least two adaptations to a benthic lifestyle, and suggests good olfactory sensitivity, with secondary folding enhancing the hypothetical flat sensory surface area by up to 70%. PMID:23630172

  11. Fish stomach contents in benthic macroinvertebrate assemblage assessments.

    PubMed

    Tupinambás, T H; Pompeu, P S; Gandini, C V; Hughes, R M; Callisto, M

    2015-01-01

    The choice of sampling gears to assess benthic macroinvertebrate communities depends on environmental characteristics, study objectives, and cost effectiveness. Because of the high foraging capacity and diverse habitats and behaviors of benthophagous fishes, their stomach contents may offer a useful sampling tool in studies of benthic macroinvertebrates, especially in large, deep, fast rivers that are difficult to sample with traditional sediment sampling gear. Our objective was to compare the benthic macroinvertebrate communities sampled from sediments with those sampled from fish stomachs. We collected benthic macroinvertebrates and fish from three different habitat types (backwater, beach, riffle) in the wet season, drying season, and dry season along a single reach of the Grande River (Paraná River Basin, southeast Brazil). We sampled sediments through use of a Petersen dredge (total of 216 grabs) and used gill nets to sample fish (total of 36 samples). We analyzed the stomach contents of three commonly occurring benthophagous fish species (Eigenmannia virescens, Iheringichthys labrosus, Leporinus amblyrhynchus). Chironomids dominated in both sampling methods. Macroinvertebrate taxonomic composition and abundances from fish stomachs differed from those from sediment samples, but less so from riffles than from backwater and beach habitats. Macroinvertebrate taxa from E. virescens stomachs were more strongly correlated with sediment samples from all three habitats than were those from the other two species. The species accumulation curves and higher mean dispersion values, compared with with sediment samples suggest that E. virescens is more efficient than sediment samples and the other fish studied at collecting benthic taxa. We conclude that by analyzing the stomach contents of benthophagous fishes it is possible to assess important characteristics of benthic communities (dispersion, taxonomic composition and diversity). This is especially true for studies

  12. Dispersal similarly shapes both population genetics and community patterns in the marine realm

    PubMed Central

    Chust, Guillem; Villarino, Ernesto; Chenuil, Anne; Irigoien, Xabier; Bizsel, Nihayet; Bode, Antonio; Broms, Cecilie; Claus, Simon; Fernández de Puelles, María L.; Fonda-Umani, Serena; Hoarau, Galice; Mazzocchi, Maria G.; Mozetič, Patricija; Vandepitte, Leen; Veríssimo, Helena; Zervoudaki, Soultana; Borja, Angel

    2016-01-01

    Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits. We compiled large data sets of population genetic structure (98 benthic macroinvertebrate and 35 planktonic species) and biogeographic data (2193 benthic macroinvertebrate and 734 planktonic species). We estimated dispersal distances from population genetic data (i.e., FST vs. geographic distance) and from β-diversity at the community level. Dispersal distances ranked the biological groups in the same order at both genetic and community levels, as predicted by organism dispersal ability and seascape connectivity: macrozoobenthic species without dispersing larvae, followed by macrozoobenthic species with dispersing larvae and plankton (phyto- and zooplankton). This ranking order is associated with constraints to the movement of macrozoobenthos within the seabed compared with the pelagic habitat. We showed that dispersal limitation similarly determines the connectivity degree of communities and populations, supporting the predictions of neutral theories in marine biodiversity patterns. PMID:27344967

  13. Dispersal similarly shapes both population genetics and community patterns in the marine realm.

    PubMed

    Chust, Guillem; Villarino, Ernesto; Chenuil, Anne; Irigoien, Xabier; Bizsel, Nihayet; Bode, Antonio; Broms, Cecilie; Claus, Simon; Fernández de Puelles, María L; Fonda-Umani, Serena; Hoarau, Galice; Mazzocchi, Maria G; Mozetič, Patricija; Vandepitte, Leen; Veríssimo, Helena; Zervoudaki, Soultana; Borja, Angel

    2016-01-01

    Dispersal plays a key role to connect populations and, if limited, is one of the main processes to maintain and generate regional biodiversity. According to neutral theories of molecular evolution and biodiversity, dispersal limitation of propagules and population stochasticity are integral to shaping both genetic and community structure. We conducted a parallel analysis of biological connectivity at genetic and community levels in marine groups with different dispersal traits. We compiled large data sets of population genetic structure (98 benthic macroinvertebrate and 35 planktonic species) and biogeographic data (2193 benthic macroinvertebrate and 734 planktonic species). We estimated dispersal distances from population genetic data (i.e., FST vs. geographic distance) and from β-diversity at the community level. Dispersal distances ranked the biological groups in the same order at both genetic and community levels, as predicted by organism dispersal ability and seascape connectivity: macrozoobenthic species without dispersing larvae, followed by macrozoobenthic species with dispersing larvae and plankton (phyto- and zooplankton). This ranking order is associated with constraints to the movement of macrozoobenthos within the seabed compared with the pelagic habitat. We showed that dispersal limitation similarly determines the connectivity degree of communities and populations, supporting the predictions of neutral theories in marine biodiversity patterns. PMID:27344967

  14. Traffic congestion and dispersion in Hurricane evacuation

    NASA Astrophysics Data System (ADS)

    Tanaka, Katsunori; Nagatani, Takashi; Hanaura, Hirotoshi

    2007-03-01

    We study the traffic congestion and dispersion of vehicles occurring on a single lane highway in Hurricane evacuation. The traffic congestion depends on both sensitivity and speed of the leading vehicle. When the leading vehicle moves with low speed, the vehicular traffic exhibits the stop and go-wave (oscillating congested traffic) for low sensitivity, while the traffic results in the homogeneous congested traffic for high sensitivity. The traffic dispersion is measured by the time difference between the leading and rear vehicles. The time difference fluctuates highly for the oscillating congestion traffic, while it keeps a constant value for the homogeneous congested traffic. The traffic states in Hurricane evacuation is connected to the phase diagram of conventional traffic.

  15. Dispersion-free radial transmission lines

    DOEpatents

    Caporaso, George J.; Nelson, Scott D.

    2011-04-12

    A dispersion-free radial transmission line ("DFRTL") preferably for linear accelerators, having two plane conductors each with a central hole, and an electromagnetically permeable material ("EPM") between the two conductors and surrounding a channel connecting the two holes. At least one of the material parameters of relative magnetic permeability, relative dielectric permittivity, and axial width of the EPM is varied as a function of radius, so that the characteristic impedance of the DFRTL is held substantially constant, and pulse transmission therethrough is substantially dispersion-free. Preferably, the EPM is divided into concentric radial sections, with the varied material parameters held constant in each respective section but stepwise varied between sections as a step function of the radius. The radial widths of the concentric sections are selected so that pulse traversal time across each section is the same, and the varied material parameters of the concentric sections are selected to minimize traversal error.

  16. How spatio-temporal habitat connectivity affects amphibian genetic structure

    PubMed Central

    Watts, Alexander G.; Schlichting, Peter E.; Billerman, Shawn M.; Jesmer, Brett R.; Micheletti, Steven; Fortin, Marie-Josée; Funk, W. Chris; Hapeman, Paul; Muths, Erin; Murphy, Melanie A.

    2015-01-01

    Heterogeneous landscapes and fluctuating environmental conditions can affect species dispersal, population genetics, and genetic structure, yet understanding how biotic and abiotic factors affect population dynamics in a fluctuating environment is critical for species management. We evaluated how spatio-temporal habitat connectivity influences dispersal and genetic structure in a population of boreal chorus frogs (Pseudacris maculata) using a landscape genetics approach. We developed gravity models to assess the contribution of various factors to the observed genetic distance as a measure of functional connectivity. We selected (a) wetland (within-site) and (b) landscape matrix (between-site) characteristics; and (c) wetland connectivity metrics using a unique methodology. Specifically, we developed three networks that quantify wetland connectivity based on: (i) P. maculata dispersal ability, (ii) temporal variation in wetland quality, and (iii) contribution of wetland stepping-stones to frog dispersal. We examined 18 wetlands in Colorado, and quantified 12 microsatellite loci from 322 individual frogs. We found that genetic connectivity was related to topographic complexity, within- and between-wetland differences in moisture, and wetland functional connectivity as contributed by stepping-stone wetlands. Our results highlight the role that dynamic environmental factors have on dispersal-limited species and illustrate how complex asynchronous interactions contribute to the structure of spatially-explicit metapopulations. PMID:26442094

  17. How spatio-temporal habitat connectivity affects amphibian genetic structure

    USGS Publications Warehouse

    Watts, Alexander G.; Schlichting, P; Billerman, S; Jesmer, B; Micheletti, S; Fortin, M.-J.; Funk, W.C.; Hapeman, P; Muths, Erin L.; Murphy, M.A.

    2015-01-01

    Heterogeneous landscapes and fluctuating environmental conditions can affect species dispersal, population genetics, and genetic structure, yet understanding how biotic and abiotic factors affect population dynamics in a fluctuating environment is critical for species management. We evaluated how spatio-temporal habitat connectivity influences dispersal and genetic structure in a population of boreal chorus frogs (Pseudacris maculata) using a landscape genetics approach. We developed gravity models to assess the contribution of various factors to the observed genetic distance as a measure of functional connectivity. We selected (a) wetland (within-site) and (b) landscape matrix (between-site) characteristics; and (c) wetland connectivity metrics using a unique methodology. Specifically, we developed three networks that quantify wetland connectivity based on: (i) P. maculata dispersal ability, (ii) temporal variation in wetland quality, and (iii) contribution of wetland stepping-stones to frog dispersal. We examined 18 wetlands in Colorado, and quantified 12 microsatellite loci from 322 individual frogs. We found that genetic connectivity was related to topographic complexity, within- and between-wetland differences in moisture, and wetland functional connectivity as contributed by stepping-stone wetlands. Our results highlight the role that dynamic environmental factors have on dispersal-limited species and illustrate how complex asynchronous interactions contribute to the structure of spatially-explicit metapopulations.

  18. Density-Dependent Natal Dispersal Patterns in a Leopard Population Recovering from Over-Harvest

    PubMed Central

    Fattebert, Julien; Balme, Guy; Dickerson, Tristan; Slotow, Rob; Hunter, Luke

    2015-01-01

    Natal dispersal enables population connectivity, gene flow and metapopulation dynamics. In polygynous mammals, dispersal is typically male-biased. Classically, the ‘mate competition’, ‘resource competition’ and ‘resident fitness’ hypotheses predict density-dependent dispersal patterns, while the ‘inbreeding avoidance’ hypothesis posits density-independent dispersal. In a leopard (Panthera pardus) population recovering from over-harvest, we investigated the effect of sex, population density and prey biomass, on age of natal dispersal, distance dispersed, probability of emigration and dispersal success. Over an 11-year period, we tracked 35 subadult leopards using VHF and GPS telemetry. Subadult leopards initiated dispersal at 13.6 ± 0.4 months. Age at commencement of dispersal was positively density-dependent. Although males (11.0 ± 2.5 km) generally dispersed further than females (2.7 ± 0.4 km), some males exhibited opportunistic philopatry when the population was below capacity. All 13 females were philopatric, while 12 of 22 males emigrated. Male dispersal distance and emigration probability followed a quadratic relationship with population density, whereas female dispersal distance was inversely density-dependent. Eight of 12 known-fate females and 5 of 12 known-fate male leopards were successful in settling. Dispersal success did not vary with population density, prey biomass, and for males, neither between dispersal strategies (philopatry vs. emigration). Females formed matrilineal kin clusters, supporting the resident fitness hypothesis. Conversely, mate competition appeared the main driver for male leopard dispersal. We demonstrate that dispersal patterns changed over time, i.e. as the leopard population density increased. We conclude that conservation interventions that facilitated local demographic recovery in the study area also restored dispersal patterns disrupted by unsustainable harvesting, and that this indirectly improved

  19. Summer Fish Camp.

    ERIC Educational Resources Information Center

    Remick, Dennis; Pulu, Tupou L.

    The booklet presents a description and illustrates, with photographs, the Eskimo lifestyle and the kinds of activities that occur at a summer fish camp on the Yukon River. Eleven suggested activities are listed for the teacher to present when using the booklet. Activities include studying the map of Alaska; tracing the life cycle of the fish;…

  20. An Amazing Fish Story.

    ERIC Educational Resources Information Center

    Null, Elisabeth Higgins

    2001-01-01

    Caught up in the entrepreneurial thrill of launching a new industry, high-school students in an economically distressed fishing village in Maine are playing a vital research-and-development role in partnership with their community. The result is a sophisticated aquaculture center for raising several species of fish in a laboratory setting. (MLH)

  1. Folkbiology of Freshwater Fish

    ERIC Educational Resources Information Center

    Medin, Douglas L.; Ross, Norbert O.; Atran, Scott; Cox, Douglas; Coley, John; Proffitt, Julia B.; Blok, Sergey

    2006-01-01

    Cross-cultural comparisons of categorization often confound cultural factors with expertise. This paper reports four experiments on the conceptual behavior of Native American and majority-culture fish experts. The two groups live in the same general area and engage in essentially the same set of fishing-related behaviors. Nonetheless, cultural…

  2. The Big Fish

    ERIC Educational Resources Information Center

    DeLisle, Rebecca; Hargis, Jace

    2005-01-01

    The Killer Whale, Shamu jumps through hoops and splashes tourists in hopes for the big fish, not because of passion, desire or simply the enjoyment of doing so. What would happen if those fish were obsolete? Would this killer whale be able to find the passion to continue to entertain people? Or would Shamu find other exciting activities to do…

  3. Fish Vaccines in Aquaculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vaccination is a proven, cost-effective method to prevent infectious diseases in animals. Current fish vaccines can be categorized as killed fish vaccines or modified live vaccines. The major advantage of live vaccine is their ability to stimulate both cell-mediated and humoral immune responses for ...

  4. PARASITES OF FISH

    EPA Science Inventory

    The intent of this chapter is to describe the parasites of importance to fishes maintained and used in laboratory settings. In contrast to the frist edition, the focus will be only on those parasites that pose a serious threat to or are common in fishes held in these confined en...

  5. Stress in Fish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stress in fish involves a condition disruptive of physiological homeostasis that occurs in response to unfavorable external influences and is capable of adversely affecting fish. Any stimulus that provokes stress responses is known as a stressor, disrupting a stable condition and causing a response....

  6. Habitat Specialization in Tropical Continental Shelf Demersal Fish Assemblages

    PubMed Central

    Fitzpatrick, Ben M.; Harvey, Euan S.; Heyward, Andrew J.; Twiggs, Emily J.; Colquhoun, Jamie

    2012-01-01

    The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304) collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1–10 m depth), down the fore reef slope to the reef base (10–30 m depth) then across the adjacent continental shelf (30–110 m depth). Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category) were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of connected

  7. DISSECTING HABITAT CONNECTIVITY

    EPA Science Inventory

    abstract

    Connectivity is increasingly recognized as an important element of a successful reserve design. Connectivity matters in reserve design to the extent that it promotes or hinders the viability of target populations. While conceptually straightforward, connectivity i...

  8. Connective Tissue Disorders

    MedlinePlus

    Connective tissue is the material inside your body that supports many of its parts. It is the "cellular ... their work. Cartilage and fat are examples of connective tissue. There are over 200 disorders that impact connective ...

  9. Undifferentiated Connective Tissue Disease

    MedlinePlus

    ... Home Conditions Undifferentiated Connective Tissue Disease (UCTD) Undifferentiated Connective Tissue Disease (UCTD) Make an Appointment Find a Doctor ... L. Goldstein, MD, MMSc (February 01, 2016) Undifferentiated connective tissue disease (UCTD) is a systemic autoimmune disease. This ...

  10. Cryopreservation of Fish Sperm

    NASA Astrophysics Data System (ADS)

    Kurokura, Hisashi

    Present status of research activities in cryopreservation of fish gamete in aquaculture field was introduced. More than 59 fish species have been reported in the research histories and nearly half of them were studied during recent 10 years. This means that the research activities are increasing, though commercial profit have not obtained yet. Fish species of which sperm can successfully cryopreserved is still limited comparing to numerous species in telost. One of the major obstacle for improvement of the technique is existence of wide specie specific variance in the freezing tolerance of fish sperm. The varianc can possibly be explaind thorugh the informations obtained by the studies in comparative spermatology, which is recently activated field in fish biology.

  11. Antimicrobial Peptides from Fish

    PubMed Central

    Masso-Silva, Jorge A.; Diamond, Gill

    2014-01-01

    Antimicrobial peptides (AMPs) are found widely distributed through Nature, and participate in the innate host defense of each species. Fish are a great source of these peptides, as they express all of the major classes of AMPs, including defensins, cathelicidins, hepcidins, histone-derived peptides, and a fish-specific class of the cecropin family, called piscidins. As with other species, the fish peptides exhibit broad-spectrum antimicrobial activity, killing both fish and human pathogens. They are also immunomodulatory, and their genes are highly responsive to microbes and innate immuno-stimulatory molecules. Recent research has demonstrated that some of the unique properties of fish peptides, including their ability to act even in very high salt concentrations, make them good potential targets for development as therapeutic antimicrobials. Further, the stimulation of their gene expression by exogenous factors could be useful in preventing pathogenic microbes in aquaculture. PMID:24594555

  12. Can dispersal mode predict corridor effects on plant parasites?

    SciTech Connect

    Sullivan, Lauren, L.; Johnson, Brenda, L.; Brudvig, Lars, A.; Haddad, Nick, M.

    2011-08-01

    Habitat corridors, a common management strategy for increasing connectivity in fragmented landscapes, have experimentally validated positive influences on species movement and diversity. However, long-standing concerns that corridors could negatively impact native species by spreading antagonists, such as disease, remain largely untested. Using a large-scale, replicated experiment, we evaluated whether corridors increase the incidence of plant parasites. We found that corridor impacts varied with parasite dispersal mode. Connectivity provided by corridors increased incidence of biotically dispersed parasites (galls on Solidago odora) but not of abiotically dispersed parasites (foliar fungi on S. odora and three Lespedeza spp.). Both biotically and abiotically dispersed parasites responded to edge effects, but the direction of responses varied across species. Although our results require additional tests for generality to other species and landscapes, they suggest that, when establishing conservation corridors, managers should focus on mitigating two potential negative effects: the indirect effects of narrow corridors in creating edges and direct effects of corridors in enhancing connectivity of biotically dispersed parasites.

  13. Visibility from Roads Predict the Distribution of Invasive Fishes in Agricultural Ponds

    PubMed Central

    Kizuka, Toshikazu; Akasaka, Munemitsu; Kadoya, Taku; Takamura, Noriko

    2014-01-01

    Propagule pressure and habitat characteristics are important factors used to predict the distribution of invasive alien species. For species exhibiting strong propagule pressure because of human-mediated introduction of species, indicators of introduction potential must represent the behavioral characteristics of humans. This study examined 64 agricultural ponds to assess the visibility of ponds from surrounding roads and its value as a surrogate of propagule pressure to explain the presence and absence of two invasive fish species. A three-dimensional viewshed analysis using a geographic information system quantified the visual exposure of respective ponds to humans. Binary classification trees were developed as a function of their visibility from roads, as well as five environmental factors: river density, connectivity with upstream dam reservoirs, pond area, chlorophyll a concentration, and pond drainage. Traditional indicators of human-mediated introduction (road density and proportion of urban land-use area) were alternatively included for comparison instead of visual exposure. The presence of Bluegill (Lepomis macrochirus) was predicted by the ponds' higher visibility from roads and pond connection with upstream dam reservoirs. Results suggest that fish stocking into ponds and their dispersal from upstream sources facilitated species establishment. Largemouth bass (Micropterus salmoides) distribution was constrained by chlorophyll a concentration, suggesting their lower adaptability to various environments than that of Bluegill. Based on misclassifications from classification trees for Bluegill, pond visual exposure to roads showed greater predictive capability than traditional indicators of human-mediated introduction. Pond visibility is an effective predictor of invasive species distribution. Its wider use might improve management and mitigate further invasion. The visual exposure of recipient ecosystems to humans is important for many invasive species that

  14. Model hydrocracking reactions over monometallic and bimetallic dispersed catalysts

    SciTech Connect

    Schmidt, E.; Song, C.

    1994-12-31

    Coal liquefaction involves the cleavage of methylene and dimethylene bridges connecting polycyclic aromatic units. The selected compound for model reactions is 4-(1-naphthylmethyl)bibenzyl (NMBB). This work describes the synthesis and screening of several metallic complex precursors as dispersed catalysts for hydrocracking of NMBB.

  15. MOLECULAR CONNECTIVITY STUDY OF PHENOLS AND THEIR TOXICITY TO FISH

    EPA Science Inventory

    A set of 25 substituted phenols have been examined in a QSAR study of their toxicity to fathead minnows, Pimephales promelas. The acute toxicities were measured in a flow-through system over a 96 hr. period as lethal concentration to kill 50 percent of the population, LC50. The n...

  16. Tomography of dispersive media

    PubMed

    Ernst; Herman

    2000-07-01

    When waves propagate through layered structures, the phase velocity is frequency dependent (dispersive). If one wants to reconstruct the velocity variations in this medium, conventional traveltime-based tomographic methods cannot be used, since each frequency component has a different traveltime. A tomographic method is presented for reconstructing the phase velocity of guided waves in laterally varying media. The dispersive character of guided waves is explicitly accounted for by using a phase-based error criterium instead of "picked" traveltimes. Phase velocity and source waveform can be reconstructed to within a few percent, and the algorithm is shown to be robust in the presence of interference noise. When applied to seismic field data, the reconstructed phase velocity field correlates well with the topography of the area. PMID:10923876

  17. Dispersion Analysis Research Tool

    Energy Science and Technology Software Center (ESTSC)

    1998-11-10

    The DART thermomechanical model, for the prediction of fission-product-induced swelling in aluminum dispersion fuels, calculates irradiation-induced fission gas bubbles as a function of fuel morphology. DART calculates the behavior of a rod, tube, or plate during closure of as-fabricated porosity, during which the fuel particle swelling is accommodated by the relatively soft aluminum matrix flowing into the existing porosity. The code also determines the subsequent macroscopic changes in rod diameter or plate/tube thickness caused bymore » additional fuel deformation processes. In addition, a calculation for the effect of irradiation on the thermal conductivity of the dispersion fuel, and for fuel restructuring and swelling due to the aluminum fuel reaction, amorphization, and recrystallization is included.« less

  18. Dispersion suppressors with bending

    SciTech Connect

    Garren, A.

    1985-10-01

    Dispersion suppressors of two main types are usually used. In one the cell quadrupole focussing structure is the same as in normal cells but some of the dipoles are replaced by drifts. In the other, the quadrupole strengths and/or spacings are different from those of the normal cells, but the bending is about the same as it is in the cells. In SSC designs to date, dispersion suppressors of the former type have been used, consisting of two cells with bending equivalent to one. In this note a suppressor design with normal bending and altered focussing is presented. The advantage of this scheme is that circumference is reduced. The disadvantages are that additional special quadrupoles must be provided (however, they need not be adjustable), and the maximum beta values within them are about 30% higher than the cell maxima.

  19. Nikolaevskiy equation with dispersion.

    PubMed

    Simbawa, Eman; Matthews, Paul C; Cox, Stephen M

    2010-03-01

    The Nikolaevskiy equation was originally proposed as a model for seismic waves and is also a model for a wide variety of systems incorporating a neutral "Goldstone" mode, including electroconvection and reaction-diffusion systems. It is known to exhibit chaotic dynamics at the onset of pattern formation, at least when the dispersive terms in the equation are suppressed, as is commonly the practice in previous analyses. In this paper, the effects of reinstating the dispersive terms are examined. It is shown that such terms can stabilize some of the spatially periodic traveling waves; this allows us to study the loss of stability and transition to chaos of the waves. The secondary stability diagram ("Busse balloon") for the traveling waves can be remarkably complicated. PMID:20365845

  20. Disabling Radiological Dispersal Terror

    SciTech Connect

    Hart, M

    2002-11-08

    Terror resulting from the use of a radiological dispersal device (RDD) relies upon an individual's lack of knowledge and understanding regarding its significance. Disabling this terror will depend upon realistic reviews of the current conservative radiation protection regulatory standards. It will also depend upon individuals being able to make their own informed decisions merging perceived risks with reality. Preparation in these areas will reduce the effectiveness of the RDD and may even reduce the possibility of its use.

  1. Light dispersion in space

    NASA Astrophysics Data System (ADS)

    Barbosa, L. C.

    2015-09-01

    Considering an idea of F. Arago in 1853 regarding light dispersion through the light ether in the interstellar space, this paper presents a new idea on an alternative interpretation of the cosmological red shift of the galaxies in the universe. The model is based on an analogy with the temporal material dispersion that occurs with light in the optical fiber core. Since intergalactic space is transparent, according to the model, this phenomenon is related to the gravitational potential existing in the whole space. Thus, it is possible to find a new interpretation to Hubble's constant. In space, light undergoes a dispersion process in its path, which is interpreted by a red shift equation of the type Δz = HL, since H = (d2n/dλ2 Δv Δλ), where H means the Hubble constant, n is the refractive index of the intergalactic space, Δλ is the spectral width of the extragalactic source, and Δv is the variation of the speed of light caused by the gravitational potential. We observe that this "constant" is governed by three new parameters. Light traveling the intergalactic space undergoes red shift due to this mechanism, while light amplitude decreases with time, and the wavelength always increases, thus producing the same type of behavior given by Hubble's Law. It can be demonstrated that the dark matter phenomenon is produced by the apparent speed of light of the stars on the periphery of the galaxies, without the existence of dark energy. Based on this new idea, the model of the universe is static, lacking expansion. Other phenomena may be interpreted based on this new model of the universe. We have what we call temporal gravitational dispersion of light in space produced by the variations of the speed of light, due to the presence of the gravitational potential in the whole space.

  2. Ascent trajectory dispersion analysis

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The results of a Space Transportation System ascent trajectory dispersion analysis are documented. Critical trajectory parameter values useful for the definition of lightweight external tank insulation requirements are provided. This analysis was conducted using two of the critical missions specified for the Space Transportation System: a 28.5 deg inclination trajectory launched from the Eastern Test Range (ETR) and a Western Test Range (WTR) trajectory launched into a 104 deg orbital inclination.

  3. Fish scales as biosensors for catecholamines.

    PubMed

    Elwing, H; Karlsson, J O; Grundström, N; Gustafsson, A L; von Schenck, H; Sundgren, H; Odman, S; Andersson, R G; Lundström, I

    1990-01-01

    Certain fish scales contain specialized cells (chromatophores) with pigment granulas, which can be dispersed or aggregated in the cells. The degree of aggregation is determined by a transmitter substance, noradrenaline, released by the sympathetic nerve endings in the skin. Isolated scales from, for example, cuckoo wrasse (Labrus ossifagus) retain a large sensitivity to externally applied noradrenaline (or more generally catecholamines) for several weeks. The degree of aggregation in isolated scales can be measured objectively by simple photometric techniques. We demonstrate in this paper how fish scales can be used to monitor catecholamine levels in human blood plasma. A discussion of other potential biosensor applications of this intact biological receptor-effector system is also given. PMID:2271145

  4. Larval dispersal drives trophic structure across Pacific coral reefs.

    PubMed

    Stier, Adrian C; Hein, Andrew M; Parravicini, Valeriano; Kulbicki, Michel

    2014-01-01

    Top predators are a critical part of healthy ecosystems. Yet, these species are often absent from spatially isolated habitats leading to the pervasive view that fragmented ecological communities collapse from the top down. Here we study reef fish from coral reef communities across the Pacific Ocean. Our analysis shows that species richness of reef fish top predators is relatively stable across habitats that vary widely in spatial isolation and total species richness. In contrast, species richness of prey reef fish declines rapidly with increasing isolation. By consequence, species-poor communities from isolated islands have three times as many predator species per prey species as near-shore communities. We develop and test a colonization-extinction model to reveal how larval dispersal patterns shape this ocean-scale gradient in trophic structure. PMID:25412873

  5. Dispersibility of Amphibious Montmorillonite

    NASA Astrophysics Data System (ADS)

    Yeh, Meng-Heng; Hwang, Weng-Sing; Kuo, Wuei-Jueng

    2005-09-01

    The objective of this study is to develop a suitable method to convert hydrophilic montmorillonite into amphibious montmorillonite by replacing the sodium ions normally found in clay with poly(oxyethylene) (POE)-amide chlorite cations. Amphibious montmorillonite has a high d-spacing and good dispersion characteristics in many different types of solutions, including those having an intermediate hydrophilic lipophilic balance (HLB) value. Four different modifying cations are tested and X-ray diffraction analysis is performed to measure the resulting changes in the d-spacing of the MMT. Scanning electron microscopy is employed to investigate the morphology of the modified clays. A laser-doppler particle analyzer is used to measure the particle size of the clays in various solutions. Dobrat’s method is applied to calculate the dispersibility of each clay and Stoke’s law is used to evaluate the settling rate. The results indicate that the d-spacing of the POE-amide chlorite cation modified montmorillonite increases from 1.28 to 3.51 nm. The amphibious montmorillonite demonstrates good dispersion characteristics in eight commonly employed coating solutions with intermediate HLB values.

  6. Succinimide lubricating oil dispersant

    SciTech Connect

    Wisotsky, M.J.; Bloch, R.; Brownwell, D.W.; Chen, F.J.; Gutierrez, A.

    1987-08-11

    A lubricating oil composition is described exhibiting improved dispersancy in both gasoline and diesel engines comprising a major amount of lubricating oil and 0.5 to 10 weight percent of a dispersant, the dispersant being prepared in a sequential process comprising the steps of: (a) in a first step reacting an oil-soluble polyolefin succinic anhydride, the olefin being a C/sub 3/ or C/sub 4/ olefin and an alkylene polyamine of the formula H/sub 2/N(CH/sub 2/)/sub n/(NH(CH/sub 2/)/sub n/)/sub m/sup -// NH/sub 2/ wherein n is 2 or 3 and m is 0 to 10, in a molar ratio of about 1.0 to 2.2 moles of polyolefin succinic anhydride per mole of polyamine, and (b) reacting the product of step (a) with dicarboxylic acid anhydride selected from the group consisting of maleic anhydride and succinic anhydride in sufficient molar proportions to provide a total mole ratio of about 2,3 to 3.0 moles of anhydride compounds per mole of polyamine.

  7. Spatial asymmetries in connectivity influence colonization-extinction dynamics.

    PubMed

    Acevedo, Miguel A; Fletcher, Robert J; Tremblay, Raymond L; Meléndez-Ackerman, Elvia J

    2015-10-01

    Movement has broad implications for many areas of biology, including evolution, community and population ecology. Movement is crucial in metapopulation ecology because it facilitates colonization and reduces the likelihood of local extinction via rescue effects. Most metapopulation modeling approaches describe connectivity using pair-wise Euclidean distances resulting in the simplifying assumption of a symmetric connectivity pattern. Yet, assuming symmetric connectivity when populations show net asymmetric movement patterns may result in biased estimates of colonization and extinction, and may alter interpretations of the dynamics and conclusions regarding the viability of metapopulations. Here, we use a 10-year time series on a wind-dispersed orchid Lepanthes rupestris that anchors its roots in patches of moss growing on trees or boulders along streams, to test for the role of connectivity asymmetries in explaining the colonization-extinction dynamics of this orchid in a network of 975 patches. We expected that wind direction could highly alter dispersal direction in this orchid. To account for this potential asymmetry, we modified the connectivity measure traditionally used in metapopulation models to allow for asymmetric effective distances between patches and subsequently estimated colonization and extinction probabilities using a dynamic occupancy modeling approach. Asymmetric movement was prevalent in the L. rupestris metapopulation and incorporating potential dispersal asymmetries resulted in higher colonization estimates in larger patches and more accurate models. Accounting for dispersal asymmetries may reveal connectivity effects where they were previously assumed to be negligible and may provide more reliable conclusions regarding the role of connectivity in patch dynamics. PMID:26054613

  8. Influence of a dispersant on the bioaccumulation of phenanthrene by topsmelt (Atherinops affinis).

    PubMed

    Mielbrecht, E E; Wolfe, M F; Tjeerdema, R S; Sowby, M L

    2005-05-01

    Chemical dispersants enhance oil spill dispersion by forming water-accommodated micelles with oil droplets. However, how dispersants alter bioavailability and subsequent bioaccumulation of hydrocarbons is not well understood. Thus, the goal was to investigate the influence of a chemical dispersant on the disposition (uptake, biotransformation, and depuration) of a model hydrocarbon, [14C]-phenanthrene ([14C]PHN), by larval topsmelt (Atherinops affinis). Exposure was via aqueous-only or combined dietary and aqueous routes from a water-accommodated fraction (WAF) of Prudhoe Bay Crude Oil (PBCO) or a WAF of Corexit 9527-dispersed PBCO (DO). Trophic transfer was measured by incorporating into exposure media both a rotifer (Brachionus plicatilis) as food for the fish and a phytoplankton (Isochrysis galbana) as food for the rotifers. Short-term (4 h) bioconcentration of PHN was significantly decreased in topsmelt when oil was treated with dispersant (P < 0.05), but differences diminished after 12 h. When trophic transfer was incorporated, PHN accumulation was initially delayed but after 12 h attained similar levels. Dispersant use also significantly decreased the proportion of biotransformed PHN (as 9-phenanthrylsulfate) produced by topsmelt (P < 0.05). However, overall PHN depuration was not affected by dispersant use. Thus, chemical dispersant use in oil spill response may reduce short-term uptake but not long-term accumulation of hydrocarbons such as PHN in pelagic fish. PMID:15814309

  9. Broadening our approaches to studying dispersal in raptors

    USGS Publications Warehouse

    Morrison, J.L.; Wood, P.B.

    2009-01-01

    Dispersal is a behavioral process having consequences for individual fitness and population dynamics. Recent advances in technology have spawned new theoretical examinations and empirical studies of the dispersal process in birds, providing opportunities for examining how this information may be applied to studies of the dispersal process in raptors. Many raptors are the focus of conservation efforts; thus, reliable data on all aspects of a species' population dynamics, including dispersal distances, movement rates, and mortality rates of dispersers, are required for population viability analyses that are increasingly used to inform management. Here, we address emerging issues and novel approaches used in the study of avian dispersal, and provide suggestions to consider when developing and implementing studies of dispersal in raptors. Clarifying study objectives is essential for selection of an appropriate methodology and sample size needed to obtain accurate estimates of movement distances and rates. Identifying an appropriate study-area size will allow investigators to avoid underestimating population connectivity and important population parameters. Because nomadic individuals of some species use temporary settling areas or home ranges before breeding, identification of these areas is critical for conservation efforts focusing on habitats other than breeding sites. Study designs for investigating raptor dispersal also should include analysis of environmental and social factors influencing dispersal, to improve our understanding of condition-dependent dispersal strategies. Finally, we propose a terminology for use in describing the variety of movements associated with dispersal behavior in raptors, and we suggest this terminology could be used consistently to facilitate comparisons among studies. ?? 2009 The Raptor Research Foundation, Inc.

  10. 26 CFR 31.3306(c)(17)-1 - Fishing services.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Salmon and halibut fishing. Services performed in connection with the catching or taking of salmon or... taking of salmon or halibut, for commercial purposes, nor the services of any other individual...

  11. 26 CFR 31.3306(c)(17)-1 - Fishing services.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Salmon and halibut fishing. Services performed in connection with the catching or taking of salmon or... taking of salmon or halibut, for commercial purposes, nor the services of any other individual...

  12. 26 CFR 31.3306(c)(17)-1 - Fishing services.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Salmon and halibut fishing. Services performed in connection with the catching or taking of salmon or... taking of salmon or halibut, for commercial purposes, nor the services of any other individual...

  13. 26 CFR 31.3306(c)(17)-1 - Fishing services.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Salmon and halibut fishing. Services performed in connection with the catching or taking of salmon or... taking of salmon or halibut, for commercial purposes, nor the services of any other individual...

  14. Rheological properties of Y{sub 2}O{sub 3}-ZrO{sub 2} suspensions with various dispersants

    SciTech Connect

    Schwenk, R.; Syskakis, E.; Kountouros, P.

    1995-09-01

    The viscosity of Y{sub 2}O{sub 3}-ZrO{sub 2} suspensions with 50-75 wt.% solid in a toluene-based solvent has been determined using oleic acid, glycerol trioleate and menhaden fish oil as dispersants. Oleic acid is the most efficient dispersant for the given solvent-powder system. Dispersions with oleic acid show the lowest viscosity, exhibiting a minimum at a dispersant/powder ratio of 0.6 wt.%. The viscosity of tape casting slips reaches a minimum at the same dispersant/powder ratio.

  15. Population Genetics of a Trochid Gastropod Broadens Picture of Caribbean Sea Connectivity

    PubMed Central

    Díaz-Ferguson, Edgardo; Haney, Robert; Wares, John; Silliman, Brian

    2010-01-01

    Background Regional genetic connectivity models are critical for successful conservation and management of marine species. Even though rocky shore invertebrates have been used as model systems to understand genetic structure in some marine environments, our understanding of connectivity in Caribbean communities is based overwhelmingly on studies of tropical fishes and corals. In this study, we investigate population connectivity and diversity of Cittarium pica, an abundant rocky shore trochid gastropod that is commercially harvested across its natural range, from the Bahamas to Venezuela. Methodology/Principal Findings We tested for genetic structure using DNA sequence variation at the mitochondrial COI and 16S loci, AMOVA and distance-based methods. We found substantial differentiation among Caribbean sites. Yet, genetic differentiation was associated only with larger geographic scales within the Caribbean, and the pattern of differentiation only partially matched previous assessments of Caribbean connectivity, including those based on larval dispersal from hydrodynamic models. For instance, the Bahamas, considered an independent region by previous hydrodynamic studies, showed strong association with Eastern Caribbean sites in our study. Further, Bonaire (located in the east and close to the meridional division of the Caribbean basin) seems to be isolated from other Eastern sites. Conclusions/Significance The significant genetic structure and observed in C. pica has some commonalities in pattern with more commonly sampled taxa, but presents features, such as the differentiation of Bonaire, that appear unique. Further, the level of differentiation, together with regional patterns of diversity, has important implications for the application of conservation and management strategies in this commercially harvested species. PMID:20844767

  16. Three-dimensional connectivity in the Gulf of California based on a numerical model

    NASA Astrophysics Data System (ADS)

    Santiago-García, M. W.; Marinone, S. G.; Velasco-Fuentes, O. U.

    2014-04-01

    Quantifying connectivity is useful for understanding the exchange and trapping of some tracers, such as fish larvae and nutrients. In the Gulf of California, connectivity studies have been limited to certain periods and regions. The current study investigated the connectivity among 17 areas, defined by the presence of eddies and weak or strong flows as obtained from a three-dimensional non-linear baroclinic model. The particles were released into the water column and advected for 28 days using an advection-diffusion scheme. The results revealed a seasonal connectivity pattern. In the northern region, particle trapping was greater during the cyclonic circulation period (June to September) compared with the anticyclonic period (November to March). This high retention was due to both the presence of a cyclonic eddy in the central portion of the region and the intense northwestward flow off the coast of Sonora. Retentions were low for the large island region due to the intense exchange between the northern and southern regions. East of Ángel de La Guarda Island the transport occurred predominantly towards the northwest due to the nearly permanent deep flow in that direction and to a branching of the surface flow among the large islands during the anticyclonic period and the northwestward low during the cyclonic period. In the peninsular and central areas of the southern region, retentions were high due to weak flows and the presence of eddies, respectively. The greatest retention and low dispersion of particles in practically all of the provinces were recorded during the transition periods of the circulation.

  17. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, W.G.; Harris, M.T.; Scott, T.C.; Basaran, O.A.

    1996-04-02

    A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 5 figs.

  18. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, W.G.; Basaran, O.A.; Harris, M.T.

    1995-11-07

    A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 4 figs.

  19. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, W.G.; Harris, M.T.; Scott, T.C.; Basaran, O.A.

    1998-06-02

    A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 5 figs.

  20. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, Warren G.; Harris, Michael T.; Scott, Timothy C.; Basaran, Osman A.

    1998-01-01

    A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode.

  1. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, Warren G.; Harris, Michael T.; Scott, Timothy C.; Basaran, Osman A.

    1996-01-01

    A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode.

  2. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, Warren G.; Basaran, Osman A.; Harris, Michael T.

    1995-01-01

    A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode.

  3. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, W.G.; Basaran, O.A.; Harris, M.T.

    1998-04-14

    A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 4 figs.

  4. Nozzle for electric dispersion reactor

    DOEpatents

    Sisson, Warren G.; Basaran, Osman A.; Harris, Michael T.

    1998-01-01

    A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode.

  5. Effects of Sound on the Behavior of Wild, Unrestrained Fish Schools.

    PubMed

    Roberts, Louise; Cheesman, Samuel; Hawkins, Anthony D

    2016-01-01

    To assess and manage the impact of man-made sounds on fish, we need information on how behavior is affected. Here, wild unrestrained pelagic fish schools were observed under quiet conditions using sonar. Fish were exposed to synthetic piling sounds at different levels using custom-built sound projectors, and behavioral changes were examined. In some cases, the depth of schools changed after noise playback; full dispersal of schools was also evident. The methods we developed for examining the behavior of unrestrained fish to sound exposure have proved successful and may allow further testing of the relationship between responsiveness and sound level. PMID:26611050

  6. uCollaborator: Framework for STEM Project Collaboration among Geographically-Dispersed Student/Faculty Teams

    ERIC Educational Resources Information Center

    Fiore, Stephen M.; Rodriguez, Walter E.; Carstens, Deborah S.

    2012-01-01

    This paper presents a framework for facilitating communication among STEM project teams that are geographically dispersed in synchronous or asynchronous online courses. The framework has been developed to: (a) improve how engineering and technology students and faculty work with collocated and geographically-dispersed teams; and (b) to connect the…

  7. Early detection of non-native fishes using fish larvae

    EPA Science Inventory

    Our objective was to evaluate the use of fish larvae for early detection of non-native fishes, comparing traditional and molecular taxonomy approaches to investigate potential efficiencies. Fish larvae present an interesting opportunity for non-native fish early detection. First,...

  8. Which Fish Should I Eat? Perspectives Influencing Fish Consumption Choices

    PubMed Central

    Choi, Anna L.; Karagas, Margaret R.; Mariën, Koenraad; Rheinberger, Christoph M.; Schoeny, Rita; Sunderland, Elsie; Korrick, Susan

    2012-01-01

    Background: Diverse perspectives have influenced fish consumption choices. Objectives: We summarized the issue of fish consumption choice from toxicological, nutritional, ecological, and economic points of view; identified areas of overlap and disagreement among these viewpoints; and reviewed effects of previous fish consumption advisories. Methods: We reviewed published scientific literature, public health guidelines, and advisories related to fish consumption, focusing on advisories targeted at U.S. populations. However, our conclusions apply to groups having similar fish consumption patterns. Discussion: There are many possible combinations of matters related to fish consumption, but few, if any, fish consumption patterns optimize all domains. Fish provides a rich source of protein and other nutrients, but because of contamination by methylmercury and other toxicants, higher fish intake often leads to greater toxicant exposure. Furthermore, stocks of wild fish are not adequate to meet the nutrient demands of the growing world population, and fish consumption choices also have a broad economic impact on the fishing industry. Most guidance does not account for ecological and economic impacts of different fish consumption choices. Conclusion: Despite the relative lack of information integrating the health, ecological, and economic impacts of different fish choices, clear and simple guidance is necessary to effect desired changes. Thus, more comprehensive advice can be developed to describe the multiple impacts of fish consumption. In addition, policy and fishery management inter-ventions will be necessary to ensure long-term availability of fish as an important source of human nutrition. PMID:22534056

  9. Forestry practices and aquatic biodiversity: Fish

    USGS Publications Warehouse

    Gresswell, Robert E.

    2005-01-01

    In the Pacific Northwest, fish communities are found in a diverse array of aquatic habitats ranging from the large coastal rivers of the temperate rainforests, to the fragmented and sometimes ephemeral streams of the xeric interior basins, and high-elevation streams and lakes in the mountainous areas (Rieman et al. 2003). Only high-elevation lakes and streams isolated above barriers to fish passage remained historically devoid of fish because they were never invaded following Pleistocene glaciation (Smith 1981). Despite this widespread distribution and once great population abundances, taxonomic diversity of fishes in these forested systems is naturally lower than in aquatic habitats in the eastern U.S. (Reeves, Bisson, and Dambacher 1998). Interactions among factors that influence species richness in aquatic systems (e.g., basin size, long-term stability of habitat, and barriers to colonization; Smith 1981) continue to influence the occurrence and persistence of fishes in these systems today. Consequently, the larger low-elevation rivers and estuaries support the greatest variety of fish species. In the high-elevation tributary streams, fish communities are less complex because these aquatic systems were less climatically and geologically stable, and fish populations were smaller and more prone to local extirpation. Furthermore, barriers to fish passage inhibited dispersal and colonization (Smith 1981). Streams in forested landscapes generally support salmon and trout, Oncorhynchus spp., whitefish Prosopium spp., sculpins Cottus spp., suckers Catostomus spp., and minnows (Cyprinidae), but in some of the colder streams, chars (e.g., Salvelinus confluentus and Salvelinus malma) and lampreys (Petromyzontidae)may also occur (Rieman et al. 2003).Although biodiversity defined in terms of fish species richness is low in the Pacific Northwest, intraspecific variability is high, and polytypic fish species are common in the diverse aquatic habitats of the region. For

  10. Effects of habitat availability on dispersion of a stream cyprinid

    USGS Publications Warehouse

    Freeman, Mary C.; Grossman, G.D.

    1993-01-01

    We analyzed temporal changes in the dispersion of the rosyside dace,Clinostomus funduloides, (family Cyprinidae) in a headwater stream, to assess the role of habitat availability in promoting fish aggregation. The dace foraged alone and in groups of up to about 25 individuals, and dispersion varied significantly among monthly censuses conducted from May through December. In two of three study pools, dace aggregated during July, October and/or December, but spread out during other months, especially during September when dispersion did not differ significantly from random. Dispersion was not significantly correlated with the total amount of suitable habitat available to foraging dace, but during summer, corresponded to the availability of depositional areas adjacent to rapid currents. Foragers aggregated in eddies or depositional areas during high stream discharge in July, and shifted out of depositional areas when current velocities declined from July to September. During late autumn, however, aggregations formed independently of changes in habitat conditions, and dace dispersion did not vary significantly among months in a third pool. The study suggests that dace dispersion cannot be predicted from the overall availability of suitable habitat as estimated from point measurements of depth and velocity; both the occurrence of a specific habitat feature (i.e., eddies adjacent to high velocity currents) and seasonal differences in behavior more strongly influenced the spatial distribution of foragers.

  11. Photoevaporation and Disk Dispersal

    NASA Astrophysics Data System (ADS)

    Gorti, Uma

    2016-01-01

    Protoplanetary disks are depleted of their mass on short timescales by viscous accretion, which removes both gas and solids, and by photoevaporation which removes mainly gas. Photoevaporation may facilitate planetesimal formation by lowering the gas/dust mass ratio in disks. Disk dispersal sets constraints on planet formation timescales, and by controlling the availability of gas determines the type of planets that form in the disk. Photoevaporative wind mass loss rates are theoretically estimated to range from ~ 10-10 to 10-8 M ⊙, and disk lifetimes are typically ~ few Myr.

  12. Solitonization of a dispersive wave.

    PubMed

    Braud, F; Conforti, M; Cassez, A; Mussot, A; Kudlinski, A

    2016-04-01

    We report the observation of a nonlinear propagation scenario in which a dispersive wave is transformed into a fundamental soliton in an axially varying optical fiber. The dispersive wave is initially emitted in the normal dispersion region and the fiber properties change longitudinally so that the dispersion becomes anomalous at the dispersive wave wavelength, which allows it to be transformed into a soliton. The solitonic nature of the field is demonstrated by solving the direct Zakharov-Shabat scattering problem. Experimental characterization performed in spectral and temporal domains show evidence of the solitonization process in an axially varying photonic crystal fiber. PMID:27192249

  13. FISH KILLS, NORTH CAROLINA

    EPA Science Inventory

    Data related to fish kills in North Carolina are collected and stored in tables on the Web at the North Carolina Department of Environment and Natural Resources. http://www.esb.enr.state.nc.us/Fishkill/fishkill00.htm

  14. Ciguatera Fish Poisoning

    MedlinePlus

    ... By Syndrome Life Cycle Impacts Human Health Wildlife Ecosystems Socioeconomic Freshwater Regions Distribution - U.S. Distribution - World Maps ... Paralytic Shellfish Poisoning Cyanobacteria Medical Community ... Fish Poisoning Causative organisms: Gambierdiscus ...

  15. Dehydrofreezing of Fish I

    NASA Astrophysics Data System (ADS)

    Kozima, Tsuneo

    Recently, new method of removing water from perishable food were developed using dehydration sheet with material having high osmotic pressure and absorbent polymer. Dehydration sheet consist of mixture of sugar dehydrolysate and absorbent polymer covered with sem-permeable membrane, and can remove water in liquid state by contact with perishable food. Dehydration rate of fish using with dehydration sheet varied depending on species, their shape, and ambient temperature etc. Fish were dehydrated with dehydration sheet at low temperature as 0 - 5 C and frozen in cold storage room. Dehydrofrozen fish were kept it's high quality and freshness after thawing, ATPase activity of fish muscle was kept at high level after dehydrofreezing in the case of cod and alaska pollack, and flesh color of farming salmon was kept after thawing.

  16. T Cells in Fish

    PubMed Central

    Nakanishi, Teruyuki; Shibasaki, Yasuhiro; Matsuura, Yuta

    2015-01-01

    Cartilaginous and bony fish are the most primitive vertebrates with a thymus, and possess T cells equivalent to those in mammals. There are a number of studies in fish demonstrating that the thymus is the essential organ for development of T lymphocytes from early thymocyte progenitors to functionally competent T cells. A high number of T cells in the intestine and gills has been reported in several fish species. Involvement of CD4+ and CD8α+ T cells in allograft rejection and graft-versus-host reaction (GVHR) has been demonstrated using monoclonal antibodies. Conservation of CD4+ helper T cell functions among teleost fishes has been suggested in a number studies employing mixed leukocyte culture (MLC) and hapten/carrier effect. Alloantigen- and virus-specific cytotoxicity has also been demonstrated in ginbuna and rainbow trout. Furthermore, the important role of cell-mediated immunity rather than humoral immunity has been reported in the protection against intracellular bacterial infection. Recently, the direct antibacterial activity of CD8α+, CD4+ T-cells and sIgM+ cells in fish has been reported. In this review, we summarize the recent progress in T cell research focusing on the tissue distribution and function of fish T cells. PMID:26426066

  17. Bacteria dispersal by hitchhiking on zooplankton.

    PubMed

    Grossart, Hans-Peter; Dziallas, Claudia; Leunert, Franziska; Tang, Kam W

    2010-06-29

    Microorganisms and zooplankton are both important components of aquatic food webs. Although both inhabit the same environment, they are often regarded as separate functional units that are indirectly connected through nutrient cycling and trophic cascade. However, research on pathogenic and nonpathogenic bacteria has shown that direct association with zooplankton has significant influences on the bacteria's physiology and ecology. We used stratified migration columns to study vertical dispersal of hitchhiking bacteria through migrating zooplankton across a density gradient that was otherwise impenetrable for bacteria in both upward and downward directions (conveyor-belt hypothesis). The strength of our experiments is to permit quantitative estimation of transport and release of associated bacteria: vertical migration of Daphnia magna yielded an average dispersal rate of 1.3 x 10(5) x cells x Daphnia(-1) x migration cycle(-1) for the lake bacterium Brevundimonas sp. Bidirectional vertical dispersal by migrating D. magna was also shown for two other bacterial species, albeit at lower rates. The prediction that diurnally migrating zooplankton acquire different attached bacterial communities from hypolimnion and epilimnion between day and night was subsequently confirmed in our field study. In mesotrophic Lake Nehmitz, D. hyalina showed pronounced diel vertical migration along with significant diurnal changes in attached bacterial community composition. These results confirm that hitchhiking on migrating animals can be an important mechanism for rapidly relocating microorganisms, including pathogens, allowing them to access otherwise inaccessible resources. PMID:20547852

  18. Connectivity Among Salt Marsh Subhabitats: Residency and Movements of the Mummichog (Fundulus heteroclitus)

    EPA Science Inventory

    We examined connectivity among marsh subhabitats to determine the structural limits and important components of a polyhaline salt marsh by studying the patterns of abundance, residency, and movement of a numerically and ecologically dominant nektonic fish (mummichog, Fundulus het...

  19. Spatial extent and dynamics of dam impacts on tropical island freshwater fish assemblages

    USGS Publications Warehouse

    Cooney, Patrick B.; Kwak, Thomas J.

    2013-01-01

    Habitat connectivity is vital to the persistence of migratory fishes. Native tropical island stream fish assemblages composed of diadromous species require intact corridors between ocean and riverine habitats. High dams block fish migration, but low-head artificial barriers are more widespread and are rarely assessed for impacts. Among all 46 drainages in Puerto Rico, we identified and surveyed 335 artificial barriers that hinder fish migration to 74.5% of the upstream habitat. We also surveyed occupancy of native diadromous fishes (Anguillidae, Eleotridae, Gobiidae, and Mugilidae) in 118 river reaches. Occupancy models demonstrated that barriers 2 meters (m) high restricted nongoby fish migration and extirpated those fish upstream of 4-m barriers. Gobies are adapted to climbing and are restricted by 12-m barriers and extirpated upstream of 32-m barriers. Our findings quantitatively illustrate the extensive impact of low-head structures on island stream fauna and provide guidance for natural resource management, habitat restoration, and water development strategies.

  20. Estimating time-dependent connectivity in marine systems

    NASA Astrophysics Data System (ADS)

    Defne, Zafer; Ganju, Neil K.; Aretxabaleta, Alfredo

    2016-02-01

    Hydrodynamic connectivity describes the sources and destinations of water parcels within a domain over a given time. When combined with biological models, it can be a powerful concept to explain the patterns of constituent dispersal within marine ecosystems. However, providing connectivity metrics for a given domain is a three-dimensional problem: two dimensions in space to define the sources and destinations and a time dimension to evaluate connectivity at varying temporal scales. If the time scale of interest is not predefined, then a general approach is required to describe connectivity over different time scales. For this purpose, we have introduced the concept of a "retention clock" that highlights the change in connectivity through time. Using the example of connectivity between protected areas within Barnegat Bay, New Jersey, we show that a retention clock matrix is an informative tool for multitemporal analysis of connectivity.

  1. Dispersal of three strains of hatchery-reared lake trout in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.

    1987-01-01

    Rates of dispersal and resultant geographical distributions were determined for three strains of hatchery-reared lake trout (Salvelinus namaycush) stocked at six sites in U.S. waters of Lake Ontario. The strains were Lake Superior (SUP); Clearwater Lake, Manitoba (CWL); and Seneca Lake, New York (SEN). The fish were recovered with bottom trawls fished during July and August 1980-1985 at 16 locations, extending from Toronto southward and eastward along the south shore to Dablon Point at the east end of the lake. For SUP fish stocked as spring yearlings, the mean distances from stocking site to capture location 2, 14, and 26 months after stocking were 12, 57, and 62 km, respectively, for fish released at four south-shore sites and 5, 34, and 38 km for fish released at two eastern outlet basin sites. Rates of dispersal for the CWL fish were similar to those of the SUP strain for fish stocked at the four south-shore sites, but were considerably less for fish stocked in the eastern outlet basin. The SEN strain was stocked only in the eastern outlet basin; their dispersal was similar to that of the SUP strain. For fish of the same age, SUP fish stocked as fall fingerlings became more widely dispersed than those stocked as spring yearlings. Movement of lake trout between the eastern outlet basin and the lake proper was limited. Large numbers of fish were captured on the Niagara Bar, but few moved past there into the west end of the lake. Movements of lake trout from stocking sites were generally with the prevailing currents. Differences between geographical distributions of the SUP and CWL strains were probably due to the influence of different current regimes at the depths they occupied. These results will be useful in selecting the best genetic strains of lake trout for rehabilitating the species in Lake Ontario, as well as for identifying the best stocking sizes and maximizing post-stocking survival of hatchery-reared fish.

  2. Impacts of urbanization on stream habitat and fish across multiple spatial scales.

    PubMed

    Wang, L; Lyons, J; Kanehl, P; Bannerman, R

    2001-08-01

    We analyzed the relation of the amount and spatial pattern of land cover with stream fish communities, in-stream habitat, and baseflow in 47 small southeastern Wisconsin, USA, watersheds encompassing a gradient of predominantly agricultural to predominantly urban land uses. The amount of connected impervious surface in the watershed was the best measure of urbanization for predicting fish density, species richness, diversity, and index of biotic integrity (IBI) score; bank erosion; and base flow. However, connected imperviousness was not significantly correlated with overall habitat quality for fish. Nonlinear models were developed using quantile regression to predict the maximum possible number of fish species, IBI score, and base flow for a given level of imperviousness. At watershed connected imperviousness levels less than about 8%, all three variables could have high values, whereas at connected imperviousness levels greater than 12% their values were inevitably low. Connected imperviousness levels between 8 and 12% represented a threshold region where minor changes in urbanization could result in major changes in stream condition. In a spatial analysis, connected imperviousness within a 50-m buffer along the stream or within a 1.6-km radius upstream of the sampling site had more influence on stream fish and base flow than did comparable amounts of imperviousness further away. Our results suggest that urban development that minimizes amount of connected impervious surface and establishes undeveloped buffer areas along streams should have less impact than conventional types of development. PMID:11443388

  3. Fish assemblage response to a small dam removal in the Eightmile River system, Connecticut, USA.

    PubMed

    Poulos, Helen M; Miller, Kate E; Kraczkowski, Michelle L; Welchel, Adam W; Heineman, Ross; Chernoff, Barry

    2014-11-01

    We examined the effects of the Zemko Dam removal on the Eightmile River system in Salem, Connecticut, USA. The objective of this research was to quantify spatiotemporal variation in fish community composition in response to small dam removal. We sampled fish abundance over a 6-year period (2005-2010) to quantify changes in fish assemblages prior to dam removal, during drawdown, and for three years following dam removal. Fish population dynamics were examined above the dam, below the dam, and at two reference sites by indicator species analysis, mixed models, non-metric multidimensional scaling, and analysis of similarity. We observed significant shifts in fish relative abundance over time in response to dam removal. Changes in fish species composition were variable, and they occurred within 1 year of drawdown. A complete shift from lentic to lotic fishes failed to occur within 3 years after the dam was removed. However, we did observe increases in fluvial and transition (i.e., pool head, pool tail, or run) specialist fishes both upstream and downstream from the former dam site. Our results demonstrate the importance of dam removal for restoring river connectivity for fish movement. While the long-term effects of dam removal remain uncertain, we conclude that dam removals can have positive benefits on fish assemblages by enhancing river connectivity and fluvial habitat availability. PMID:25022888

  4. Dispersive transport across interfaces

    NASA Astrophysics Data System (ADS)

    Berkowitz, Brian; Adler, Pierre

    2015-04-01

    Experiments demonstrating asymmetrical dispersive transport of a conservative tracer across interfaces between different porous materials have recently been performed. Here, this phenomenon is studied numerically on the pore scale. The flow field is derived by solving the Stokes equation. The dispersive transport is simulated by a large number of particles undergoing random walks under the simultaneous action of convection and diffusion. Two main two-dimensional configurations are studied; each consists of two segments (called coarse and fine) with the same structure, porosity, and length along the main flow, but different characteristic solid/pore sizes. One structure consists of two channels containing cavities of different sizes, and the second of square "grains" of different sizes. At time t=0, a large number of particles is injected (as a pulse) around a given cross-section. The corresponding breakthrough curves (BTCs) are registered as functions of time at six different cross sections. Calculations are made twice; in the first case (CtoF), particles are injected in the coarse side and are transported towards the fine one; in the second one (FtoC), the opposite case is studied. These calculations are performed for various Péclet numbers (Pe). Comparison of the resulting BTCs shows features that are similar to experimental observations, but with qualitative and quantitative differences. The influences of the medium, of the injection and observation planes, and of Pe are detailed and discussed. A BTC for pulse injection can be characterized by its maximum M(t_M) and the time tM at which it occurs. The observed differences for channels bounded by cavities are very small. However for the granular structures, M(t_M) is always larger for FtoC than for CtoF ; tM depends on all the parameters, namely Pe, the size ratio between the large and small grains, the injection and the observation planes. The numerical results are systematically compared with solutions of one

  5. SMED - Sulphur MEditerranean Dispersion

    NASA Astrophysics Data System (ADS)

    Salerno, Giuseppe G.; Sellitto, Pasquale; Corradini, Stefano; Di Sarra, Alcide Giorgio; Merucci, Luca; Caltabiano, Tommaso; La Spina, Alessandro

    2016-04-01

    Emissions of volcanic gases and particles can have profound impacts on terrestrial environment, atmospheric composition, climate forcing, and then on human health at various temporal and spatial scales. Volcanic emissions have been identified as one of the largest sources of uncertainty in our understanding of recent climate change trends. In particular, a primary role is acted by sulphur dioxide emission due to its conversion to volcanic sulphate aerosol via atmospheric oxidation. Aerosols may play a key role in the radiative budget and then in photochemistry and tropospheric composition. Mt. Etna is one of the most prodigious and persistent emitters of gasses and particles on Earth, accounting for about 10% of global average volcanic emission of CO2 and SO2. Its sulphur emissions stand for 0.7 × 106 t S/yr9 and then about 10 times bigger than anthropogenic sulphur emissions in the Mediterranean area. Centrepiece of the SMED project is to advance the understanding of volcanogenic sulphur dioxide and sulphate aerosol particles dispersion and radiative impact on the downwind Mediterranean region by an integrated approach between ground- and space-based observations and modelling. Research is addressed by exploring the potential relationship between proximal SO2 flux and aerosol measured remotely in the volcanic plume of Mt. Etna between 2000 and 2014 and distal aerosol ground-based measurements in Lampedusa, Greece, and Malta from AERONET network. Ground data are combined with satellite multispectral polar and geostationary imagers able to detect and retrieve volcanic ash and SO2. The high repetition time of SEVIRI (15 minutes) will ensure the potential opportunity to follow the entire evolution of the volcanic cloud, while, the higher spatial resolution of MODIS (1x1 km2), are exploited for investigating the probability to retrieve volcanic SO2 abundances from passive degassing. Ground and space observations are complemented with atmospheric Lagrangian model

  6. A brief history of commercial fishing in Lake Erie

    USGS Publications Warehouse

    Applegate, Vernon C.; Van Meter, Harry D.

    1970-01-01

    Salient features of the development of the industry from about 1815 to 1968, changes in fishing gears and methods, changes in the kinds and abundance of fishes caught, and the attendant effects of disappearing species on the stability of the fishery are described. The history and present status of the walleye, yellow perch, and eight other fishes, still taken in commercial quantities, are presented in more detail and are considered in the context of their effect on the current moribund state of the U.S. fishery. Past and present contributions of Lake Erie's tributaries and northerly connecting waters to the fishery are outlined briefly. The "outlook" for the fishery under present conditions of selective overfishing for high-value species, excessive pollution, ineffective and uncoordinated regulation, and antiquated methods of handling, processing, and marketing fish are discussed, and possible solutions to these problems are suggested.

  7. Natural dispersion revisited.

    PubMed

    Johansen, Øistein; Reed, Mark; Bodsberg, Nils Rune

    2015-04-15

    This paper presents a new semi-empirical model for oil droplet size distributions generated by single breaking wave events. Empirical data was obtained from laboratory experiments with different crude oils at different stages of weathering. The paper starts with a review of the most commonly used model for natural dispersion, which is followed by a presentation of the laboratory study on oil droplet size distributions formed by breaking waves conducted by SINTEF on behalf of the NOAA/UNH Coastal Response Research Center. The next section presents the theoretical and empirical foundation for the new model. The model is based on dimensional analysis and contains two non-dimensional groups; the Weber and Reynolds number. The model was validated with data from a full scale experimental oil spill conducted in the Haltenbanken area offshore Norway in July 1982, as described in the last section of the paper. PMID:25752537

  8. Rapid effects of marine reserves via larval dispersal.

    PubMed

    Cudney-Bueno, Richard; Lavín, Miguel F; Marinone, Silvio G; Raimondi, Peter T; Shaw, William W

    2009-01-01

    Marine reserves have been advocated worldwide as conservation and fishery management tools. It is argued that they can protect ecosystems and also benefit fisheries via density-dependent spillover of adults and enhanced larval dispersal into fishing areas. However, while evidence has shown that marine reserves can meet conservation targets, their effects on fisheries are less understood. In particular, the basic question of if and over what temporal and spatial scales reserves can benefit fished populations via larval dispersal remains unanswered. We tested predictions of a larval transport model for a marine reserve network in the Gulf of California, Mexico, via field oceanography and repeated density counts of recently settled juvenile commercial mollusks before and after reserve establishment. We show that local retention of larvae within a reserve network can take place with enhanced, but spatially-explicit, recruitment to local fisheries. Enhancement occurred rapidly (2 yrs), with up to a three-fold increase in density of juveniles found in fished areas at the downstream edge of the reserve network, but other fishing areas within the network were unaffected. These findings were consistent with our model predictions. Our findings underscore the potential benefits of protecting larval sources and show that enhancement in recruitment can be manifested rapidly. However, benefits can be markedly variable within a local seascape. Hence, effects of marine reserve networks, positive or negative, may be overlooked when only focusing on overall responses and not considering finer spatially-explicit responses within a reserve network and its adjacent fishing grounds. Our results therefore call for future research on marine reserves that addresses this variability in order to help frame appropriate scenarios for the spatial management scales of interest. PMID:19129910

  9. Atlantic reef fish biogeography and evolution

    USGS Publications Warehouse

    Floeter, S.R.; Rocha, L.A.; Robertson, D.R.; Joyeux, J.C.; Smith-Vaniz, W.F.; Wirtz, P.; Edwards, A.J.; Barreiros, J.P.; Ferreira, C.E.L.; Gasparini, J.L.; Brito, A.; Falcon, J.M.; Bowen, B.W.; Bernardi, G.

    2008-01-01

    Aim: To understand why and when areas of endemism (provinces) of the tropical Atlantic Ocean were formed, how they relate to each other, and what processes have contributed to faunal enrichment. Location: Atlantic Ocean. Methods: The distributions of 2605 species of reef fishes were compiled for 25 areas of the Atlantic and southern Africa. Maximum-parsimony and distance analyses were employed to investigate biogeographical relationships among those areas. A collection of 26 phylogenies of various Atlantic reef fish taxa was used to assess patterns of origin and diversification relative to evolutionary scenarios based on spatio-temporal sequences of species splitting produced by geological and palaeoceanographic events. We present data on faunal (species and genera) richness, endemism patterns, diversity buildup (i.e. speciation processes), and evaluate the operation of the main biogeographical barriers and/or filters. Results: Phylogenetic (proportion of sister species) and distributional (number of shared species) patterns are generally concordant with recognized biogeographical provinces in the Atlantic. The highly uneven distribution of species in certain genera appears to be related to their origin, with highest species richness in areas with the greatest phylogenetic depth. Diversity buildup in Atlantic reef fishes involved (1) diversification within each province, (2) isolation as a result of biogeographical barriers, and (3) stochastic accretion by means of dispersal between provinces. The timing of divergence events is not concordant among taxonomic groups. The three soft (non-terrestrial) inter-regional barriers (mid-Atlantic, Amazon, and Benguela) clearly act as 'filters' by restricting dispersal but at the same time allowing occasional crossings that apparently lead to the establishment of new populations and species. Fluctuations in the effectiveness of the filters, combined with ecological differences among provinces, apparently provide a mechanism

  10. Determinants of fish assemblage structure in Northwestern Great Plains streams

    USGS Publications Warehouse

    Mullen, J.A.; Bramblett, R.G.; Guy, C.S.; Zale, A.V.; Roberts, D.W.

    2011-01-01

    Prairie streams are known for their harsh and stochastic physical conditions, and the fish assemblages therein have been shown to be temporally variable. We assessed the spatial and temporal variation in fish assemblage structure in five intermittent, adventitious northwestern Great Plains streams representing a gradient of watershed areas. Fish assemblages and abiotic conditions varied more spatially than temporally. The most important variables explaining fish assemblage structure were longitudinal position and the proportion of fine substrates. The proportion of fine substrates increased proceeding upstream, approaching 100% in all five streams, and species richness declined upstream with increasing fine substrates. High levels of fine substrate in the upper reaches appeared to limit the distribution of obligate lithophilic fish species to reaches further downstream. Species richness and substrates were similar among all five streams at the lowermost and uppermost sites. However, in the middle reaches, species richness increased, the amount of fine substrate decreased, and connectivity increased as watershed area increased. Season and some dimensions of habitat (including thalweg depth, absolute distance to the main-stem river, and watershed size) were not essential in explaining the variation in fish assemblages. Fish species richness varied more temporally than overall fish assemblage structure did because common species were consistently abundant across seasons, whereas rare species were sometimes absent or perhaps not detected by sampling. The similarity in our results among five streams varying in watershed size and those from other studies supports the generalization that spatial variation exceeds temporal variation in the fish assemblages of prairie and warmwater streams. Furthermore, given longitudinal position, substrate, and stream size, general predictions regarding fish assemblage structure and function in prairie streams are possible. ?? American

  11. Prolactin signaling in erythrophores and xanthophores of teleost fish.

    PubMed

    Oshima, N; Goto, M

    2000-01-01

    Prolactin directly affects erythrophores and xanthophores of teleost fish, resulting in pigment dispersion. In the present study, signal transduction elicited by prolactin was examined using split-tail fin preparations of the rose bitterling and Nile tilapia, and cultured erythrophores and xanthophores from the paradise goby and rose bitterling. When antibodies to the prolactin receptor were added to an ovine prolactin (oPRL) solution, pigment dispersion within cultured cells was significantly inhibited, suggesting the existence of a prolactin receptor in the cell membrane. In mammals and birds, prolactin receptors belong to a cytokine receptor superfamily and signal through a tyrosine kinase-mediated pathway. Therefore, we examined the effects of three kinds of protein tyrosine kinase inhibitors on pigment dispersion elicited by oPRL. None of those inhibitors depressed the response. On the other hand, lithium ions (an inhibitor of adenylate cyclase) and H-88 and H-89 (inhibitors of protein kinase A) decreased the levels of oPRL-induced pigment dispersion in a dose-dependent manner. In cultured cells treated with cholera toxin for 3 hrs, the effect of oPRL was irreversible, indicating the possible involvement of Gs protein in the prolactin action. From these results, we conclude that cAMP may be a second messenger in the dispersion of pigment induced by prolactin and that a novel protein receptor coupled with a Gs protein may be present in the membrane of erythrophores and xanthophores of teleost fish. PMID:11041355

  12. Cowlitz Falls Fish Passage.

    SciTech Connect

    1995-09-01

    The upper Cowlitz was once home to native salmon and steelhead. But the combined impacts of overharvest, farming, logging and road building hammered fish runs. And in the 1960s, a pair of hydroelectric dams blocked the migration path of ocean-returning and ocean-going fish. The lower Cowlitz still supports hatchery runs of chinook, coho and steelhead. But some 200 river miles in the upper river basin--much of it prime spawning and rearing habitat--have been virtually cut off from the ocean for over 26 years. Now the idea is to trap-and-haul salmon and steelhead both ways and bypass previously impassable obstacles in the path of anadromous fish. The plan can be summarized, for the sake of explanation, in three steps: (1) trap and haul adult fish--collect ocean-returning adult fish at the lowermost Cowlitz dam, and truck them upstream; (2) reseed--release the ripe adults above the uppermost dam, and let them spawn naturally, at the same time, supplement these runs with hatchery born fry that are reared and imprinted in ponds and net pens in the watershed; (3) trap and haul smolts--collection the new generation of young fish as they arrive at the uppermost Cowlitz dam, truck them past the three dams, and release them to continue their downstream migration to the sea. The critical part of any fish-collection system is the method of fish attraction. Scientists have to find the best combination of attraction system and screens that will guide young fish to the right spot, away from the turbine intakes. In the spring of 1994 a test was made of a prototype system of baffles and slots on the upriver face of the Cowlitz Falls Dam. The prototype worked at 90% efficiency in early tests, and it worked without the kind of expensive screening devices that have been installed on other dams. Now that the success of the attraction system has been verified, Harza engineers and consultants will design and build the appropriate collection part of the system.

  13. Immunity to fish rhabdoviruses

    USGS Publications Warehouse

    Purcell, Maureen K.; Laing, Kerry J.; Winton, James R.

    2012-01-01

    Members of the family Rhabdoviridae are single-stranded RNA viruses and globally important pathogens of wild and cultured fish and thus relatively well studied in their respective hosts or other model systems. Here, we review the protective immune mechanisms that fish mount in response to rhabdovirus infections. Teleost fish possess the principal components of innate and adaptive immunity found in other vertebrates. Neutralizing antibodies are critical for long-term protection from fish rhabdoviruses, but several studies also indicate a role for cell-mediated immunity. Survival of acute rhabdoviral infection is also dependent on innate immunity, particularly the interferon (IFN) system that is rapidly induced in response to infection. Paradoxically, rhabdoviruses are sensitive to the effects of IFN but virulent rhabdoviruses can continue to replicate owing to the abilities of the matrix (M) protein to mediate host-cell shutoff and the non-virion (NV) protein to subvert programmed cell death and suppress functional IFN. While many basic features of the fish immune response to rhabdovirus infections are becoming better understood, much less is known about how factors in the environment affect the ecology of rhabdovirus infections in natural populations of aquatic animals.

  14. Immunity to Fish Rhabdoviruses

    PubMed Central

    Purcell, Maureen K.; Laing, Kerry J.; Winton, James R.

    2012-01-01

    Members of the family Rhabdoviridae are single-stranded RNA viruses and globally important pathogens of wild and cultured fish and thus relatively well studied in their respective hosts or other model systems. Here, we review the protective immune mechanisms that fish mount in response to rhabdovirus infections. Teleost fish possess the principal components of innate and adaptive immunity found in other vertebrates. Neutralizing antibodies are critical for long-term protection from fish rhabdoviruses, but several studies also indicate a role for cell-mediated immunity. Survival of acute rhabdoviral infection is also dependent on innate immunity, particularly the interferon (IFN) system that is rapidly induced in response to infection. Paradoxically, rhabdoviruses are sensitive to the effects of IFN but virulent rhabdoviruses can continue to replicate owing to the abilities of the matrix (M) protein to mediate host-cell shutoff and the non‑virion (NV) protein to subvert programmed cell death and suppress functional IFN. While many basic features of the fish immune response to rhabdovirus infections are becoming better understood, much less is known about how factors in the environment affect the ecology of rhabdovirus infections in natural populations of aquatic animals. PMID:22355456

  15. Fish robotics and hydrodynamics

    NASA Astrophysics Data System (ADS)

    Lauder, George

    2010-11-01

    Studying the fluid dynamics of locomotion in freely-swimming fishes is challenging due to difficulties in controlling fish behavior. To provide better control over fish-like propulsive systems we have constructed a variety of fish-like robotic test platforms that range from highly biomimetic models of fins, to simple physical models of body movements during aquatic locomotion. First, we have constructed a series of biorobotic models of fish pectoral fins with 5 fin rays that allow detailed study of fin motion, forces, and fluid dynamics associated with fin-based locomotion. We find that by tuning fin ray stiffness and the imposed motion program we can produce thrust both on the fin outstroke and instroke. Second, we are using a robotic flapping foil system to study the self-propulsion of flexible plastic foils of varying stiffness, length, and trailing edge shape as a means of investigating the fluid dynamic effect of simple changes in the properties of undulating bodies moving through water. We find unexpected non-linear stiffness-dependent effects of changing foil length on self-propelled speed, and as well as significant effects of trailing edge shape on foil swimming speed.

  16. [Particle dispersion by ordered motion in mixing layers]. [Annual report

    SciTech Connect

    Troutt, T.R.

    1989-12-31

    Multiphase mixing in turbulent flows is a key element in many practical energy conversion, chemical mixing and pollutant dispersal problems. Numerous important technological and environmental processes could be better addressed with improvements in understanding in this area. Progress in developing understanding of this field, however, has traditionally been difficult because of the complexities involved with the turbulent flows employed to provide the mixing mechanisms. To address this problem from a new perspective several years ago this research group initiated an ongoing investigation concerning the potential connections between organized turbulent vortex structures and the particle dispersion process. This report details activities during this reporting period.

  17. ACOUSTIC RECTIFICATION IN DISPERSIVE MEDIA

    SciTech Connect

    Cantrell, John H.

    2009-03-03

    It is shown that the shapes of acoustic radiation-induced static strain and displacement pulses (rectified acoustic pulses) are defined locally by the energy density of the generating waveform. Dispersive properties are introduced analytically by assuming that the rectified pulses are functionally dependent on a phase factor that includes both dispersive and nonlinear terms. The dispersion causes an evolutionary change in the shape of the energy density profile that leads to the generation of solitons experimentally observed in fused silica.

  18. Acoustic Rectification in Dispersive Media

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.

    2008-01-01

    It is shown that the shapes of acoustic radiation-induced static strain and displacement pulses (rectified acoustic pulses) are defined locally by the energy density of the generating waveform. Dispersive properties are introduced analytically by assuming that the rectified pulses are functionally dependent on a phase factor that includes both dispersive and nonlinear terms. The dispersion causes an evolutionary change in the shape of the energy density profile that leads to the generation of solitons experimentally observed in fused silica.

  19. Seascape and life-history traits do not predict self-recruitment in a coral reef fish.

    PubMed

    Herrera, Marcela; Nanninga, Gerrit B; Planes, Serge; Jones, Geoffrey P; Thorrold, Simon R; Saenz-Agudelo, Pablo; Almany, Glenn R; Berumen, Michael L

    2016-08-01

    The persistence and resilience of many coral reef species are dependent on rates of connectivity among sub-populations. However, despite increasing research efforts, the spatial scale of larval dispersal remains unpredictable for most marine metapopulations. Here, we assess patterns of larval dispersal in the angelfish Centropyge bicolor in Kimbe Bay, Papua New Guinea, using parentage and sibling reconstruction analyses based on 23 microsatellite DNA loci. We found that, contrary to previous findings in this system, self-recruitment (SR) was virtually absent at both the reef (0.4-0.5% at 0.15 km(2)) and the lagoon scale (0.6-0.8% at approx. 700 km(2)). While approximately 25% of the collected juveniles were identified as potential siblings, the majority of sibling pairs were sampled from separate reefs. Integrating our findings with earlier research from the same system suggests that geographical setting and life-history traits alone are not suitable predictors of SR and that high levels of localized recruitment are not universal in coral reef fishes. PMID:27512132

  20. Seascape and life-history traits do not predict self-recruitment in a coral reef fish

    PubMed Central

    Nanninga, Gerrit B.; Planes, Serge; Jones, Geoffrey P.; Thorrold, Simon R.; Saenz-Agudelo, Pablo; Almany, Glenn R.; Berumen, Michael L.

    2016-01-01

    The persistence and resilience of many coral reef species are dependent on rates of connectivity among sub-populations. However, despite increasing research efforts, the spatial scale of larval dispersal remains unpredictable for most marine metapopulations. Here, we assess patterns of larval dispersal in the angelfish Centropyge bicolor in Kimbe Bay, Papua New Guinea, using parentage and sibling reconstruction analyses based on 23 microsatellite DNA loci. We found that, contrary to previous findings in this system, self-recruitment (SR) was virtually absent at both the reef (0.4–0.5% at 0.15 km2) and the lagoon scale (0.6–0.8% at approx. 700 km2). While approximately 25% of the collected juveniles were identified as potential siblings, the majority of sibling pairs were sampled from separate reefs. Integrating our findings with earlier research from the same system suggests that geographical setting and life-history traits alone are not suitable predictors of SR and that high levels of localized recruitment are not universal in coral reef fishes. PMID:27512132

  1. Weakly connected neural nets

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1990-01-01

    A new neural network architecture is proposed based upon effects of non-Lipschitzian dynamics. The network is fully connected, but these connections are active only during vanishingly short time periods. The advantages of this architecture are discussed.

  2. Identifying natural flow regimes using fish communities

    NASA Astrophysics Data System (ADS)

    Chang, Fi-John; Tsai, Wen-Ping; Wu, Tzu-Ching; Chen, Hung-kwai; Herricks, Edwin E.

    2011-10-01

    SummaryModern water resources management has adopted natural flow regimes as reasonable targets for river restoration and conservation. The characterization of a natural flow regime begins with the development of hydrologic statistics from flow records. However, little guidance exists for defining the period of record needed for regime determination. In Taiwan, the Taiwan Eco-hydrological Indicator System (TEIS), a group of hydrologic statistics selected for fisheries relevance, is being used to evaluate ecological flows. The TEIS consists of a group of hydrologic statistics selected to characterize the relationships between flow and the life history of indigenous species. Using the TEIS and biosurvey data for Taiwan, this paper identifies the length of hydrologic record sufficient for natural flow regime characterization. To define the ecological hydrology of fish communities, this study connected hydrologic statistics to fish communities by using methods to define antecedent conditions that influence existing community composition. A moving average method was applied to TEIS statistics to reflect the effects of antecedent flow condition and a point-biserial correlation method was used to relate fisheries collections with TEIS statistics. The resulting fish species-TEIS (FISH-TEIS) hydrologic statistics matrix takes full advantage of historical flows and fisheries data. The analysis indicates that, in the watersheds analyzed, averaging TEIS statistics for the present year and 3 years prior to the sampling date, termed MA(4), is sufficient to develop a natural flow regime. This result suggests that flow regimes based on hydrologic statistics for the period of record can be replaced by regimes developed for sampled fish communities.

  3. Directional connectivity in hydrology and ecology.

    PubMed

    Larsen, Laurel G; Choi, Jungyill; Nungesser, Martha K; Harvey, Judson W

    2012-12-01

    Quantifying hydrologic and ecological connectivity has contributed to understanding transport and dispersal processes and assessing ecosystem degradation or restoration potential. However, there has been little synthesis across disciplines. The growing field of ecohydrology and recent recognition that loss of hydrologic connectivity is leading to a global decline in biodiversity underscore the need for a unified connectivity concept. One outstanding need is a way to quantify directional connectivity that is consistent, robust to variations in sampling, and transferable across scales or environmental settings. Understanding connectivity in a particular direction (e.g., streamwise, along or across gradient, between sources and sinks, along cardinal directions) provides critical information for predicting contaminant transport, planning conservation corridor design, and understanding how landscapes or hydroscapes respond to directional forces like wind or water flow. Here we synthesize progress on quantifying connectivity and develop a new strategy for evaluating directional connectivity that benefits from use of graph theory in ecology and percolation theory in hydrology. The directional connectivity index (DCI) is a graph-theory based, multiscale metric that is generalizable to a range of different structural and functional connectivity applications. It exhibits minimal sensitivity to image rotation or resolution within a given range and responds intuitively to progressive, unidirectional change. Further, it is linearly related to the integral connectivity scale length--a metric common in hydrology that correlates well with actual fluxes--but is less computationally challenging and more readily comparable across different landscapes. Connectivity-orientation curves (i.e., directional connectivity computed over a range of headings) provide a quantitative, information-dense representation of environmental structure that can be used for comparison or detection of

  4. Directional connectivity in hydrology and ecology

    USGS Publications Warehouse

    Larsen, Laurel G.; Choi, Jungyill; Nungesser, Martha K.; Harvey, Judson W.

    2012-01-01

    Quantifying hydrologic and ecological connectivity has contributed to understanding transport and dispersal processes and assessing ecosystem degradation or restoration potential. However, there has been little synthesis across disciplines. The growing field of ecohydrology and recent recognition that loss of hydrologic connectivity is leading to a global decline in biodiversity underscore the need for a unified connectivity concept. One outstanding need is a way to quantify directional connectivity that is consistent, robust to variations in sampling, and transferable across scales or environmental settings. Understanding connectivity in a particular direction (e.g., streamwise, along or across gradient, between sources and sinks, along cardinal directions) provides critical information for predicting contaminant transport, planning conservation corridor design, and understanding how landscapes or hydroscapes respond to directional forces like wind or water flow. Here we synthesize progress on quantifying connectivity and develop a new strategy for evaluating directional connectivity that benefits from use of graph theory in ecology and percolation theory in hydrology. The directional connectivity index (DCI) is a graph-theory based, multiscale metric that is generalizable to a range of different structural and functional connectivity applications. It exhibits minimal sensitivity to image rotation or resolution within a given range and responds intuitively to progressive, unidirectional change. Further, it is linearly related to the integral connectivity scale length—a metric common in hydrology that correlates well with actual fluxes—but is less computationally challenging and more readily comparable across different landscapes. Connectivity-orientation curves (i.e., directional connectivity computed over a range of headings) provide a quantitative, information-dense representation of environmental structure that can be used for comparison or detection of

  5. An ecological basis for future fish habitat restoration efforts in the Huron-Erie Corridor

    USGS Publications Warehouse

    Hondorp, Darryl W.; Roseman, Edward F.; Manny, Bruce A.

    2014-01-01

    This perspective describes the major natural and anthropogenic forces driving change in the abundance and quality of fish habitats in the Huron-Erie Corridor (HEC), the Great Lakes connecting channel comprised of the St. Clair River, the Lake St. Clair, and the Detroit River. Channels connecting the Laurentian Great Lakes discharge large volumes of water equal to or greater than most other large rivers in the world that is of consistent high quality and volume, all year. Owing to creation of the St. Lawrence Seaway through the Great Lakes, the connecting channels have been modified by dredging over 200 km of deep-draft shipping lanes with a maintained depth of no less than 8.2 m. Combined with modification of their shorelines for housing and industries, use of the connecting channels for discharges of industrial and municipal wastes and shipping has resulted in numerous beneficial use impairments, such as restrictions on fish and wildlife consumption, degradation of fish and wildlife populations, and losses of fish and wildlife habitat. Various options for remediation of native fish populations and their habitats in the Great Lakes connecting channels, including construction of spawning habitat for threatened and high-value food fishes, such as lake sturgeon (Acipenser fulvescens), walleye (Sander vitreus), and lake whitefish (Coregonus clupeaformis), have been implemented successfully in two of the channels, and form the basis for further recommended research described in this article.

  6. Extensive dispersal of Roanoke logperch (Percina rex) inferred from genetic marker data

    USGS Publications Warehouse

    Roberts, James H.; Angermeier, Paul; Hallerman, Eric M.

    2016-01-01

    The dispersal ecology of most stream fishes is poorly characterised, complicating conservation efforts for these species. We used microsatellite DNA marker data to characterise dispersal patterns and effective population size (Ne) for a population of Roanoke logperchPercina rex, an endangered darter (Percidae). Juveniles and candidate parents were sampled for 2 years at sites throughout the Roanoke River watershed. Dispersal was inferred via genetic assignment tests (ATs), pedigree reconstruction (PR) and estimation of lifetime dispersal distance under a genetic isolation-by-distance model. Estimates of Ne varied from 105 to 1218 individuals, depending on the estimation method. Based on PR, polygamy was frequent in parents of both sexes, with individuals spawning with an average of 2.4 mates. The sample contained 61 half-sibling pairs, but only one parent–offspring pair and no full-sib pairs, which limited our ability to discriminate natal dispersal of juveniles from breeding dispersal of their parents between spawning events. Nonetheless, all methods indicated extensive dispersal. The AT indicated unrestricted dispersal among sites ≤15 km apart, while siblings inferred by the PR were captured an average of 14 km and up to 55 km apart. Model-based estimates of median lifetime dispersal distance (6–24 km, depending on assumptions) bracketed AT and PR estimates, indicating that widely dispersed individuals do, on average, contribute to gene flow. Extensive dispersal of P. rex suggests that darters and other small benthic stream fishes may be unexpectedly mobile. Monitoring and management activities for such populations should encompass entire watersheds to fully capture population dynamics.

  7. The welfare of fish.

    PubMed

    Iwama, George K

    2007-05-01

    Our interactions with fish cover a wide range of activities including enjoying them as pets to consuming them as food. I propose that we confine the consideration of the welfare of fish to their physiology, and not join the discussion on whether fish can feel pain and suffering, as humans. A significant proportion of the papers on animal welfare center on whether non-human animals can feel pain, and suffer as humans. This is a question that never can be answered unequivocally. The premise of the present paper is that we have an ethical responsibility to respect the life and wellbeing of all organisms. Thus, we should concentrate on the behavioural, physiological, and cellular indicators of their well-being and attempt to minimize a state of stress in the animals that we have in our care or influence. PMID:17578254

  8. Dynamite fishing in Tanzania.

    PubMed

    Slade, Lorna M; Kalangahe, Baraka

    2015-12-30

    Fishing using explosives is common in Tanzanian waters; it is considered to be more widely practised now than at any other point in history. Mwambao Coastal Community Network, a Tanzanian NGO carried out a multi-stakeholder consultation in April 2014 initiated through the concern of private investors and tourism operators. Consultations were held with villagers, fisheries officers, government officers, hoteliers, dive operators, fish processors, NGOs and other key individuals, and shed some light on key factors enabling this practice to flourish. Key areas identified for attention include engendering political will at all levels, upholding of the law through a non-corrupt enforcement and judicial system, and defining clear roles and responsibilities for monitoring and surveillance. The work identified other successful initiatives which have tackled this pervasive practice including projects that build local capacity for marine governance, villages that have declared themselves intolerant of blast-fishing, and private-public partnerships for patrol and protection. PMID:26475022

  9. Claudins in teleost fishes

    PubMed Central

    Kolosov, Dennis; Bui, Phuong; Chasiotis, Helen; Kelly, Scott P

    2013-01-01

    Teleost fishes are a large and diverse animal group that represent close to 50% of all described vertebrate species. This review consolidates what is known about the claudin (Cldn) family of tight junction (TJ) proteins in teleosts. Cldns are transmembrane proteins of the vertebrate epithelial/endothelial TJ complex that largely determine TJ permeability. Cldns achieve this by expressing barrier or pore forming properties and by exhibiting distinct tissue distribution patterns. So far, ~63 genes encoding for Cldn TJ proteins have been reported in 16 teleost species. Collectively, cldns (or Cldns) are found in a broad array of teleost fish tissues, but select genes exhibit restricted expression patterns. Evidence to date strongly supports the view that Cldns play a vital role in the embryonic development of teleost fishes and in the physiology of tissues and organ systems studied thus far. PMID:24665402

  10. Fish hematology and associated disorders.

    PubMed

    Grant, Krystan R

    2015-01-01

    Fish health is a growing concern as pets, education, and aquaculture evolves. For the veterinary staff, fish handling, diagnostics, medicine, and surgery may require specialized training and equipment in comparison with terrestrial and arboreal animals, simply because of their aquatic nature and diversity. Fish hematology is one diagnostic tool that may not require additional equipment, may be inexpensive, and provide useful information in guiding treatment options. Challenges involving hematology may include handling and restraint, venipuncture, evaluation, and interpretation. In this article, strategies for these challenges are discussed for teleost (bony fish) and elasmobranch (cartilaginous fish) fish types. PMID:25421028

  11. Fish Hematology and Associated Disorders.

    PubMed

    Grant, Krystan R

    2015-09-01

    Fish health is a growing concern as pets, education, and aquaculture evolves. For the veterinary staff, fish handling, diagnostics, medicine, and surgery may require specialized training and equipment in comparison with terrestrial and arboreal animals, simply because of their aquatic nature and diversity. Fish hematology is one diagnostic tool that may not require additional equipment, may be inexpensive, and provide useful information in guiding treatment options. Challenges involving hematology may include handling and restraint, venipuncture, evaluation, and interpretation. In this article, strategies for these challenges are discussed for teleost (bony fish) and elasmobranch (cartilaginous fish) fish types. PMID:26297413

  12. MedlinePlus Connect

    MedlinePlus

    ... MedlinePlus Connect? MedlinePlus Connect links health IT systems, patient portals and electronic health record (EHR) systems to relevant, ... care providers when they need it via their patient portal or EHR. How does MedlinePlus Connect work? MedlinePlus ...

  13. Polarizability of the pion: No conflict between dispersion theory and chiral perturbation theory

    SciTech Connect

    Pasquini, B.; Drechsel, D.; Scherer, S.

    2008-06-15

    Recent attempts to determine the pion polarizability by dispersion relations yield values that disagree with the predictions of chiral perturbation theory. These dispersion relations are based on specific forms for the absorptive part of the Compton amplitudes. The analytic properties of these forms are examined, and the strong enhancement of intermediate-meson contributions is shown to be connected with spurious singularities. If the basic requirements of dispersion relations are taken into account, the results of dispersion theory and effective field theory are not inconsistent.

  14. Growth and immune system performance to assess the effect of dispersed oil on juvenile sea bass (Dicentrarchus labrax).

    PubMed

    Dussauze, Matthieu; Danion, Morgane; Floch, Stéphane Le; Lemaire, Philippe; Theron, Michaël; Pichavant-Rafini, Karine

    2015-10-01

    The potential impact of chemically and mechanically dispersed oil was assessed in a model fish of European coastal waters, the sea bass Dicentrarchus labrax. Juvenile sea bass were exposed for 48h to dispersed oil (mechanically and chemically) or dispersants alone. The impact of these exposure conditions was assessed using growth and immunity. The increase observed in polycyclic aromatic hydrocarbon metabolites in bile indicated oil contamination in the fish exposed to chemical and mechanical dispersion of oil without any significant difference between these two groups. After 28 days of exposure, no significant differences were observed in specific growth rate,apparent food conversion efficiency and daily feeding). Following the oil exposure, fish immunity was assessed by a challenge with Viral Nervous Necrosis Virus (VNNV). Fish mortality was observed over a 42 day period. After 12 days post-infection, cumulative mortality was significantly different between the control group (16% p≤0.05) and the group exposed to chemical dispersion of oil (30% p≤0.05). However, at the end of the experiment, no significant difference was recorded in cumulative mortality or in VNNV antibodies secreted in fish in responses to the treatments. These data suggested that in our experimental condition, following the oil exposure, sea bass growth was not affected whereas an impact on immunity was observed during the first days. However, this effect on the immune system did not persist over time. PMID:26092553

  15. Improved carbon nanotubes dispersion through polar dispersant agents in polyamide

    NASA Astrophysics Data System (ADS)

    Morici, Elisabetta; Arrigo, Rossella; Teresi, Rosalia; Dintcheva, Nadka Tzankova

    2016-05-01

    The potential enhancement of the nanocomposite properties, with respect to the neat matrix, is strictly related to uniform distribution and dispersion of the nanofillers in the host polymer. In this work, two dispersant agents, particularly a polar wax and a silanol polyhedral oligomeric silsesquioxanes POSS, have been used in order to improve the dispersion of bare and functionalized carbon nanotubes in polyamide matrix. To ensure a good compatibility between matrix and nanofillers, the dispersing agents having specific polarity have been chosen, in order to match that of the matrix. Significant alterations of the mechanical and rheological behaviour due to dispersion action of used additives have been noticed and discussed, also considering the obtained morphology.

  16. Interior below decks in fish hold looking forward. Fish hatch ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior below decks in fish hold looking forward. Fish hatch opening is at upper left, ceiling planks and knees at center and right. - Purse Seiner SHENANDOAH, Gig Harbor Peninsula Historical Society and Museum, Gig Harbor, Pierce County, WA

  17. Fish consumption and track to a fish feed formulation

    NASA Astrophysics Data System (ADS)

    Cai-Juan, Soong; Ramli, Razamin; Rahman, Rosshairy Abdul

    2015-12-01

    Strategically located in the equator, Malaysia is blessed with plenty of fish supply. The high demand in fish consumption has helped the development in the fishery industry and provided numerous jobs in the secondary sector, contributing significantly to the nation's income. A survey was conducted to understand the trend of current demands for fish for the purpose of designing a feed formulation, which is still limited in this area of study. Results showed that grouper fish in restaurants commanded a very high price compared to other species of fish. Tiger grouper gained the highest demand in most restaurants, while giant grouper had the highest price in restaurants. Due to the demand and challenges to culture this type of fish, a framework for fish feed formulation is proposed. The formulation framework when materialized could be an alternative to the use of trash fish as the feed for grouper.

  18. The relationship between pelagic larval duration and range size in tropical reef fishes: a synthetic analysis

    PubMed Central

    Lester, Sarah E; Ruttenberg, Benjamin I

    2005-01-01

    We address the conflict in earlier results regarding the relationship between dispersal potential and range size. We examine all published pelagic larval duration data for tropical reef fishes. Larval duration is a convenient surrogate for dispersal potential in marine species that are sedentary as adults and that therefore only experience significant dispersal during their larval phase. Such extensive quantitative dispersal data are only available for fishes and thus we use a unique dataset to examine the relationship between dispersal potential and range size. We find that dispersal potential and range size are positively correlated only in the largest ocean basin, the Indo-Pacific, and that this pattern is driven primarily by the spatial distribution of habitat and dispersal barriers. Furthermore, the relationship strengthens at higher taxonomic levels, suggesting an evolutionary mechanism. We document a negative correlation between species richness and larval duration at the family level in the Indo-Pacific, implying that speciation rate may be negatively related to dispersal potential. If increased speciation rate within a taxonomic group results in smaller range sizes within that group, speciation rate could regulate the association between range size and dispersal potential. PMID:16007745

  19. Cost effective system for monitoring of fish migration with a camera

    NASA Astrophysics Data System (ADS)

    Sečnik, Matej; Brilly, Mitja; Vidmar, Andrej

    2016-04-01

    Within the European LIFE project Ljubljanica connects (LIFE10 NAT/SI/000142) we have developed a cost-effective solution for the monitoring of fish migration through the fish passes with the underwater camera. In the fish pass at Ambrožev trg and in the fish pass near the Fužine castle we installed a video camera called "Fishcam" to be able to monitor the migration of fish through the fish passes and success of its reconstruction. Live stream from fishcams installed in the fishpassesis available on our project website (http://ksh.fgg.uni-lj.si/ljubljanicaconnects/ang/12_camera). The system for the fish monitoring is made from two parts. First is the waterproof box for the computer with charger and the second part is the camera itself. We used a high sensitive Sony analogue camera. The advantage of this camera is that it has very good sensitivity in low light conditions, so it can take good quality pictures even at night with a minimum additional lighting. For the night recording we use additional IR reflector to illuminate passing fishes. The camera is connected to an 8-inch tablet PC. We decided to use a tablet PC because it is quite small, cheap, it is relatively fast and has a low power consumption. On the computer we use software which has advanced motion detection capabilities, so we can also detect the small fishes. When the fish is detected by a software, its photograph is automatically saved to local hard drive and for backup also on Google drive. The system for monitoring of fish migration has turned out to work very well. From the beginning of monitoring in June 2015 to end of the year there were more than 100.000 photographs produced. The first analysis of them was already prepared estimating fish species and their frequency in passing the fish pass.

  20. Hybrid Dispersion Laser Scanner

    PubMed Central

    Goda, K.; Mahjoubfar, A.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

    2012-01-01

    Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points. PMID:22685627

  1. Modeling volcanic ash dispersal

    ScienceCinema

    None

    2011-10-06

    Explosive volcanic eruptions inject into the atmosphere large amounts of volcanic material (ash, blocks and lapilli). Blocks and larger lapilli follow ballistic and non-ballistic trajectories and fall rapidly close to the volcano. In contrast, very fine ashes can remain entrapped in the atmosphere for months to years, and may affect the global climate in the case of large eruptions. Particles having sizes between these two end-members remain airborne from hours to days and can cover wide areas downwind. Such volcanic fallout entails a serious threat to aircraft safety and can create many undesirable effects to the communities located around the volcano. The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard scenarios and/or to give short-term forecasts during emergency situations. This talk will be focused on the main aspects related to modeling volcanic ash dispersal and fallout with application to the well known problem created by the Eyjafjöll volcano in Iceland. Moreover, a short description of the main volcanic monitoring techniques is presented.

  2. Modeling volcanic ash dispersal

    SciTech Connect

    2010-10-22

    Explosive volcanic eruptions inject into the atmosphere large amounts of volcanic material (ash, blocks and lapilli). Blocks and larger lapilli follow ballistic and non-ballistic trajectories and fall rapidly close to the volcano. In contrast, very fine ashes can remain entrapped in the atmosphere for months to years, and may affect the global climate in the case of large eruptions. Particles having sizes between these two end-members remain airborne from hours to days and can cover wide areas downwind. Such volcanic fallout entails a serious threat to aircraft safety and can create many undesirable effects to the communities located around the volcano. The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard scenarios and/or to give short-term forecasts during emergency situations. This talk will be focused on the main aspects related to modeling volcanic ash dispersal and fallout with application to the well known problem created by the Eyjafjöll volcano in Iceland. Moreover, a short description of the main volcanic monitoring techniques is presented.

  3. Fish as a proxy for African paleogeography: results from both extant and fossil taxa and prospects to constrain faunal exchange pathway through time

    NASA Astrophysics Data System (ADS)

    Otero, Olga; Joordens, Josephine; Dettai, Agnès; Christ, Leemans; Pinton, Aurélie

    2016-04-01

    We assume that basin boundaries constitute barriers to dispersal for freshwater fish and as a consequence that basin geomorphology and connectivity, and its changes through time, can be reconstructed thanks to fish evolutionary history. Firstly, this primary intuitive hypothesis is supported by patterns of fish distribution in the different basins and sub-basins of modern Africa, at both a specific and a generic level, and in certain cases at a family level. This is illustrated by the fact that hydrographical basin boundaries are reflected in the ichthyological provinces as defined and used by ichthyologists for a long time. Moreover, we show that at a continental scale, the hierarchical fish distribution patterns fit with main geological and climatic events according to their depth in time and amplitude [1]. Secondly, we further tested this hypothesis in several ways: (1) through the phylogeographical study of the catfish genus Synodontis [2], chosen because of its modern distribution and its rich fossil record, and (2) through the examination of the fossil record and systematics of the African lungfish Protopterus [3], of the catfish Calarius and of an extinct acanthomorph fish called Semlikiichthys [4,5]. We were then able to correlate these fish histories with quaternary climate change and with geological events throughout the Tertiary in Africa. Our conclusions are also corroborated by existing fish phylogenies that overlap with our region of interest, and elsewhere. While in the last years an increasing number of molecular phylogenetical studies support correlation between fish evolution and basin history at shallow time scales, our studies (and a few other studies) also demonstrate the relevance of fish evolution to work at deeper time and larger geological scales, depending on the taxon distribution and age. Moreover, we plead for the inclusion of fossils when available. Indeed, for extant taxa they are useful to calibrate molecular clocks but also to

  4. Significant effects of fishing gear selectivity on fish life history

    NASA Astrophysics Data System (ADS)

    Liang, Zhenlin; Sun, Peng; Yan, Wei; Huang, Liuyi; Tang, Yanli

    2014-06-01

    Over the past few decades, extreme changes have occurred in the characters of exploited fish populations. The majority of these changes have affected the growth traits of fish life history, which include a smaller size-at-age, an earlier age-at-maturation and among others. Currently, the causes of these life history traits changes still require systematic analyses and empirical studies. The explanations that have been cited are merely expressed in terms of fish phenotypic adaptation. It has been claimed that the original traits of fish can be recovered once the intensity of exploitation of the fish is controlled. Sustained environmental and fishing pressure will change the life history traits of most fish species, so the fish individual's traits are still in small size-at-age and at earlier age-at-maturation in exploited fish populations. In this paper, we expressed our view of points that fishing gear has imposed selectivity on fish populations and individuals as various other environmental factors have done and such changes are unrecoverable. According to the existing tend of exploited fish individual's life history traits, we suggested further researches in this field and provided better methods of fishery management and thereby fishery resources protection than those available early.

  5. Fish and fish oil in health promotion and disease prevention

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fish is an important dietary component due to its contribution of valuable nutrients. In addition to the high quality protein and micronutrients provided, fish is the primary source of long-chain omega-3 fatty acids which are found in oils of ‘fatty’ cold water fish. Biomedical evidence supports th...

  6. Dispersion in Unconsolidated Aquatic Sediments

    NASA Astrophysics Data System (ADS)

    Roychoudhury, A. N.

    2001-11-01

    Inert tracer breakthrough experiments were used to parameterize hydrodynamic dispersion in undisturbed cores of surface sediment from lacustrine, estuarine, and marine depositional environments. The sediments studied cover wide ranges of composition, porosity (46 to 83%), mean grain size (10 -5to 10 -2 cm), and sorting (0·48-1·26). As expected, hydrodynamic dispersion depends on the average longitudinal fluid flow velocity through the sediment plug. At linear flow velocities exceeding 10 -4 cm s -1, mechanical dispersion exceeds diffusion in all sediment cores studied. Compared to the classical studies on dispersion in sand columns, however, Peclet numbers based on particle size measurements do not provide a reliable guide for predicting the transition from molecular diffusion-dominated to mechanical dispersion-dominated flow regimes in the sediments. It is believed that the influence of pore structure on dispersion is much larger than that of particle size and that the characteristic pore lengths in the finest, highly porous sediments are orders of magnitude larger than the mean grain size. Aggregation, microlaminations, and a heterogeneous pore size distribution may all contribute to non-ideal flow conditions in the sediments. Tailing of the breakthrough curve occurred occasionally in fine grain sediment, signifying micro and macro scale dispersion and non-ideal flow behavior. Experiments showing significant non-ideal flow through the sediment plug were not used for calculation of hydrodynamic dispersion coefficient.

  7. Relative dispersion in the atmosphere

    NASA Astrophysics Data System (ADS)

    LaCasce, Joe; Graff, Lise; Guttu, Sigmund

    2014-05-01

    The relative dispersion of pairs of particles in flows is of central importance when describing environmental dispersion, for example of volcanic ash. Atmospheric relative dispersion was examined previously in two balloon experiments in the Southern Hemisphere (the EOLE and TWERLE experiments). In both cases, the dispersion at scales below 1000 km grew exponentially in time, indicating the kinetic energy spectrum is steep. Subsequent analyses suggested though that the dispersion had a power law dependence on time, implying a shallower kinetic energy spectrum. The results from studies employing synthetic particles advected by reanalysis winds are similarly inconsistent, with indications of exponential growth in some cases and power law growth in others. Here we use a different statistic---the probability density function (PDF) of pair displacements---to study dispersion the dispersion of large numbers of synthetic particles, advected by ERA-Interim reanalysis winds. The particles were deployed in the troposphere and stratosphere, both in the tropics and the extra-tropics. We examine the PDFs for the different deployments and compare them to analytical expressions derived for different turbulent inertial ranges. In line with the earlier balloon experiments, the results indicate exponential growth at the sub-deformation (1000 km) scales. At larger scales, the dispersion is anisotropic (predominantly zonal) and pair motion becomes decorrelated. Structure functions calculated from the wind data are in line with these conclusions.

  8. Preparation of alkali metal dispersions

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Landel, R. F. (Inventor)

    1968-01-01

    A method is described for producing alkali metal dispersions of high purity. The dispersions are prepared by varying the equilibrium solubility of the alkali metal in a suitable organic solvent in the presence of aromatic hydrocarbons. The equilibrium variation is produced by temperature change. The size of the particles is controlled by controlling the rate of temperature change.

  9. Mangroves enhance the biomass of coral reef fish communities in the Caribbean.

    PubMed

    Mumby, Peter J; Edwards, Alasdair J; Arias-González, J Ernesto; Lindeman, Kenyon C; Blackwell, Paul G; Gall, Angela; Gorczynska, Malgosia I; Harborne, Alastair R; Pescod, Claire L; Renken, Henk; Wabnitz, Colette C C; Llewellyn, Ghislane

    2004-02-01

    Mangrove forests are one of the world's most threatened tropical ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral reef fish often inhabit mangroves, but the importance of these nurseries to reef fish population dynamics has not been quantified. Indeed, mangroves might be expected to have negligible influence on reef fish communities: juvenile fish can inhabit alternative habitats and fish populations may be regulated by other limiting factors such as larval supply or fishing. Here we show that mangroves are unexpectedly important, serving as an intermediate nursery habitat that may increase the survivorship of young fish. Mangroves in the Caribbean strongly influence the community structure of fish on neighbouring coral reefs. In addition, the biomass of several commercially important species is more than doubled when adult habitat is connected to mangroves. The largest herbivorous fish in the Atlantic, Scarus guacamaia, has a functional dependency on mangroves and has suffered local extinction after mangrove removal. Current rates of mangrove deforestation are likely to have severe deleterious consequences for the ecosystem function, fisheries productivity and resilience of reefs. Conservation efforts should protect connected corridors of mangroves, seagrass beds and coral reefs. PMID:14765193

  10. Dispersal leads to spatial autocorrelation in species distributions: A simulation model

    USGS Publications Warehouse

    Bahn, V.; Krohn, W.B.; O'Connor, R.J.

    2008-01-01

    Compared to population growth regulated by local conditions, dispersal has been underappreciated as a central process shaping the spatial distribution of populations. This paper asks: (a) which conditions increase the importance of dispersers relative to local recruits in determining population sizes? and (b) how does dispersal influence the spatial distribution patterns of abundances among connected populations? We approached these questions with a simulation model of populations on a coupled lattice with cells of continuously varying habitat quality expressed as carrying capacities. Each cell contained a population with the basic dynamics of density-regulated growth, and was connected to other populations by immigration and emigration. The degree to which dispersal influenced the distribution of population sizes depended most strongly on the absolute amount of dispersal, and then on the potential population growth rate. Dispersal decaying in intensity with distance left close neighbours more alike in population size than distant populations, leading to an increase in spatial autocorrelation. The spatial distribution of species with low potential growth rates is more dependent on dispersal than that of species with high growth rates; therefore, distribution modelling for species with low growth rates requires particular attention to autocorrelation, and conservation management of these species requires attention to factors curtailing dispersal, such as fragmentation and dispersal barriers. ?? 2007 Elsevier B.V. All rights reserved.

  11. QT dispersion in adult hypertensives.

    PubMed Central

    Sani, Isa Muhammad; Solomon, Danbauchi Sulei; Imhogene, Oyati Albert; Ahmad, Alhassan Muhammad; Bala, Garko Sani

    2006-01-01

    Increased QT dispersion is associated with sudden cardiac death in congestive cardiac failure, hypertrophic cardiomyopathy and following myocardial infarction. Patients with hypertension--in particular, those with left ventricular hypertrophy (LVH)--are also at greater risk of sudden cardiac death. We examined whether QT dispersion, which is easily obtained from a routine ECG, correlates with LVH. One-hundred untreated patients with systemic hypertension and 78 normotensives had QT dispersion measured manually from a surface 12-lead electrocardiogram and two-dimensional echocardiography performed to measure interventricular septal thickness, posterior wall thickness and left ventricular internal diameter. Office blood pressure was also recorded. Multivariate analysis demonstrated significant relationships between QT dispersion and office systolic blood pressure, and left ventricular mass index. Manual measurement of QT dispersion might be a simple, noninvasive screening procedure to identify those hypertensives at greatest risk of sudden cardiac death in a third-world country. PMID:16623077

  12. Ooey, Gooey, Fish Guts

    ERIC Educational Resources Information Center

    Timmons, Maryellen

    2004-01-01

    Fish dissections are a great way to introduce the concepts of food webs, predator-prey relationships, and ecosystems, but these labs are expensive, messy, smelly, and require a lot of supervision because of the tools involved. The author has developed an inexpensive, safe, and clean alternative where students "dissect" simulated fish…

  13. Miniature sonar fish tag

    NASA Technical Reports Server (NTRS)

    Lovelady, R. W.; Ferguson, R. L.

    1975-01-01

    Self-powered sonar device may be implanted in body of fish. It transmits signal that can be detected with portable tracking gear or by automatic detection-and-tracking system. Operating life of over 4000 hours may be expected. Device itself may be used almost indefinitely.

  14. Yet Another Fish Tale?

    ERIC Educational Resources Information Center

    Lalasz, Robert

    2008-01-01

    Last month the "Rocky Mountain News" reported that a survey by an emeritus professor at University of Colorado Boulder found that only 23 of 825 faculty members on the campus were registered Republicans. But on his "New York Times" blog, Stanley Fish brushed off the survey's significance from a familiarly Fishian stance. A faculty's political…

  15. Puffer fish poisoning.

    PubMed Central

    Field, J

    1998-01-01

    Regarded by many as a delicacy, puffer fish (Lagocephalus scleratus) is a lethal source of food poisoning with a high mortality. It contains tetrodotoxin which can cause death by muscular paralysis, respiratory depression, and circulatory failure. A case of mild intoxication is reported and the literature reviewed. Images p336-a PMID:9785165

  16. Hydrodynamics of fossil fishes.

    PubMed

    Fletcher, Thomas; Altringham, John; Peakall, Jeffrey; Wignall, Paul; Dorrell, Robert

    2014-08-01

    From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall drag while serving a protective function. Here, we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms. PMID:24943377

  17. Colwater fish in rivers

    EPA Science Inventory

    A standard sampling protocol to assess the fish assemblages and abundances in large, coldwater rivers is most accurate and precise if consistent gears and levels of effort are used at each site. This requires thorough crew training, quality control audits, and replicate sampling...

  18. Hydrodynamics of fossil fishes

    PubMed Central

    Fletcher, Thomas; Altringham, John; Peakall, Jeffrey; Wignall, Paul; Dorrell, Robert

    2014-01-01

    From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall drag while serving a protective function. Here, we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms. PMID:24943377

  19. FishTraits Database

    USGS Publications Warehouse

    Angermeier, Paul L.; Frimpong, Emmanuel A.

    2009-01-01

    The need for integrated and widely accessible sources of species traits data to facilitate studies of ecology, conservation, and management has motivated development of traits databases for various taxa. In spite of the increasing number of traits-based analyses of freshwater fishes in the United States, no consolidated database of traits of this group exists publicly, and much useful information on these species is documented only in obscure sources. The largely inaccessible and unconsolidated traits information makes large-scale analysis involving many fishes and/or traits particularly challenging. FishTraits is a database of >100 traits for 809 (731 native and 78 exotic) fish species found in freshwaters of the conterminous United States, including 37 native families and 145 native genera. The database contains information on four major categories of traits: (1) trophic ecology, (2) body size and reproductive ecology (life history), (3) habitat associations, and (4) salinity and temperature tolerances. Information on geographic distribution and conservation status is also included. Together, we refer to the traits, distribution, and conservation status information as attributes. Descriptions of attributes are available here. Many sources were consulted to compile attributes, including state and regional species accounts and other databases.

  20. Fish-induced keriorrhea.

    PubMed

    Ling, Ka Ho; Nichols, Peter D; But, Paul Pui-Hay

    2009-01-01

    Many deep-sea fishes store large amounts of wax esters in their body for buoyancy control. Some of them are frequently caught as by-catch of tuna and other fishes. The most noteworthy ones include escolar and oilfish. The accumulation of the indigestible wax esters in the rectum through consumption of these fish engenders discharges or leakage per rectum as orange or brownish green oil, but without noticeable loss of water. This physiological response is called keriorrhea, which is variously described as "oily diarrhea," "oily orange diarrhea," or "orange oily leakage" by the mass media and bloggers on the internet. Outbreaks of keriorrhea have been repeatedly reported across continents. Additional symptoms including nausea, vomiting, abdominal cramps, and diarrhea were complained by the victims. They are probably due to anxiety or panic when suffering from keriorrhea. Escolar and oilfish are banned from import and sale in Italy, Japan, and South Korea. Rapid detection of the two fishes is imperative to ensure proper labeling and safeguarding of the public before and after any keriorrhea outbreak. PMID:19595384

  1. The Last Fish.

    ERIC Educational Resources Information Center

    Pollack, Susan

    1995-01-01

    Describes the collapse of Newfoundland's once immense northern-cod fishery in 1992 from the perspective of a family fisherman who has become an environmental activist. Discusses failures in environmental management including the overfishing of shared resources encouraged by the Canadian government and hastened by international fishing fleets and…

  2. Truck-Drivin' Fish?

    ERIC Educational Resources Information Center

    Jones, AnnMarie

    2001-01-01

    Presents an art activity that enables first-grade students to learn about color mixing by driving toys trucks through paint. Explains that the students created rainbow fish and drew the background with crayons. States that this activity demonstrates how to utilize nontraditional tools or objects when creating art. (CMK)

  3. Polynuclear aromatic hydrocarbons (PAHs) in fish from the Arabian Gulf

    SciTech Connect

    DouAbdul, A.A.Z.; Abaychi, J.K.; Al-Edanee, T.E.; Ghani, A.A.; Al-Saad, H.T.

    1987-03-01

    Emphasis has been placed upon the identification and qualification of compounds with potential adverse health effects on humans. Prominent among this group are polynuclear aromatic hydrocarbons (PAHs), several of which are known or suspected carcinogens. PAHs enter the marine environment from a variety of sources including petroleum pollution, industrial and domestic effluents, atmospheric particles, and biosynthesis by plants and microorganisms. Although one-third of the world's oil is produced around the Arabian Gulf, no detailed analysis have been conducted to determine PAHs in this region. Nevertheless, numerous investigations have shown the ability of marine organisms including fish to accumulation PAHs from solution or dispersion in seawater. When fish are harvested, a human health hazard may result. In the present communication, high performance liquid chromatography (HPLC) was used to identify and measure sixteen PAHs priority pollutants issued by US Environmental Protection Agency (EPA) in fourteen species of commercially significant fish from the NW Arabian Gulf.

  4. Transitory versus Persistent Effects of Connectivity in Environmentally Homogeneous Metacommunities

    PubMed Central

    Limberger, Romana; Wickham, Stephen A.

    2012-01-01

    While the effect of habitat connectivity on local and regional diversity has been analysed in a number of studies, time-dependent dynamics in metacommunities have received comparatively little consideration. When local patches of a metacommunity are identical in environmental conditions but differ in initial community composition, dispersal among patches may result in homogenization of local communities. In a microcosm experiment with benthic ciliates, we tested the hypothesis that the effect of connectivity on diversity is time-dependent and only transitory, with the degree of connectivity affecting the time to homogenization but not the final outcome. Six microcosms were connected to a metacommunity with one of three levels of connectivity. The six patches differed in initial community composition but were identical in environmental conditions. We found a time-dependent and transitory effect of connectivity on local and regional richness and on local Shannon diversity, while Bray-Curtis dissimilarity and regional Shannon diversity were persistently affected by connectivity. Local richness increased and regional richness decreased with connectivity during the initial phase of the experiment but soon converged to similar values in all three connectivity treatments. Local Shannon diversity was unimodally related to time, with maximum diversity reached sooner with high than with medium or low connectivity. Eventually, however, local diversity converged to similar values irrespective of connectivity. At the regional scale, Shannon diversity was persistently lower with high than with low connectivity. While initial differences in community composition vanished with medium and high connectivity, they were maintained with low connectivity resulting in persistently high beta and regional diversity. The effect of connectivity on ciliate community composition translated down to the algal resource, as stronger dominance of the superior competitor with high and medium

  5. Assessing environmental correlates of fish movement on a coral reef

    NASA Astrophysics Data System (ADS)

    Currey, Leanne M.; Heupel, Michelle R.; Simpfendorfer, Colin A.; Williams, Ashley J.

    2015-12-01

    Variation in dispersal and movement patterns of coral reef fishes is likely linked to changes in environmental conditions. Monitoring in situ environmental parameters on coral reefs in conjunction with the movements of fishes can help explain the relationship between exploited populations and their environment. Sixty adult Lethrinus miniatus were acoustically tagged and monitored along a coral reef slope for up to 1 yr. Individuals occurred more often on the reef slope during days of cooler temperatures, suggesting a thermal tolerance threshold may exist. Results indicate that individuals responded to elevated temperatures by moving away from the reef slope to deeper adjacent habitats, thus shifting their position in the water column to remain at a preferred temperature. Space use within the water column (vertical activity space) was not influenced by environmental parameters or fish size, but this result was possibly influenced by use of deeper habitat outside the acoustic array that was not monitored. With elevation of ocean temperature, L. miniatus may need to adapt to warmer waters or disperse into cooler habitats, by either shifting their distribution deeper or towards higher latitudes. Identifying key environmental drivers that affect the distribution of reef fishes is important, and may allow managers to predict the effect of these changes on exploited species.

  6. Dispersive suspended microextraction.

    PubMed

    Yang, Zhong-Hua; Liu, Yu; Lu, Yue-Le; Wu, Tong; Zhou, Zhi-Qiang; Liu, Dong-Hui

    2011-11-14

    A novel sample pre-treatment technique termed dispersive suspended microextraction (DSME) coupled with gas chromatography-flame photometric detection (GC-FPD) has been developed for the determination of eight organophosphorus pesticides (ethoprophos, malathion, chlorpyrifos, isocarbophos, methidathion, fenamiphos, profenofos, triazophos) in aqueous samples. In this method, both extraction and two phases' separation process were performed by the assistance of magnetic stirring. After separating the two phases, 1 μL of the suspended phase was injected into GC for further instrument analysis. Varieties of experiment factors which could affect the experiment results were optimized and the following were selected: 12.0 μL p-xylene was selected as extraction solvent, extraction speed was 1200 rpm, extraction time was 30 s, the restoration speed was 800 rpm, the restoration time was 8 min, and no salt was added. Under the optimum conditions, limits of detections (LODs) varied between 0.01 and 0.05 μg L(-1). The relative standard deviation (RSDs, n=6) ranged from 4.6% to 12.1%. The linearity was obtained by five points in the concentration range of 0.1-100.0 μg L(-1). Correlation coefficients (r) varied from 0.9964 to 0.9995. The enrichment factors (EFs) were between 206 and 243. In the final experiment, the developed method has been successfully applied to the determination of organophosphorus pesticides in wine and tap water samples and the obtained recoveries were between 83.8% and 101.3%. Compared with other pre-treatment methods, DSME has its own features and could achieve satisfied results for the analysis of trace components in complicated matrices. PMID:22023861

  7. 50 CFR 404.10 - Commercial fishing.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... NOAA regulations at 50 CFR part 665, subpart E as necessary. (2) Total landings for each fishing year... MONUMENT § 404.10 Commercial fishing. (a) Lobster fishing. Any commercial lobster fishing permit is...

  8. PNNL Tests Fish Passage System

    SciTech Connect

    Colotelo, Alison

    2015-03-13

    Scientists from PNNL are testing a fish transportation system developed by Whooshh Innovations. The Whooshh system uses a flexible tube that works a bit like a vacuum, guiding fish over hydroelectric dams or other structures. Compared to methods used today, this system could save money while granting fish quicker, safer passage through dams and hatcheries.

  9. Experimental evidence for extreme dispersal limitation in tropical forest birds.

    PubMed

    Moore, R P; Robinson, W D; Lovette, I J; Robinson, T R

    2008-09-01

    Movements of organisms between habitat remnants can affect metapopulation structure, community assembly dynamics, gene flow and conservation strategy. In the tropical landscapes that support the majority of global biodiversity and where forest fragmentation is accelerating, there is particular urgency to understand how dispersal across habitats mediates the demography, distribution and differentiation of organisms. By employing unique dispersal challenge experiments coupled with exhaustive inventories of birds in a Panamanian lacustrine archipelago, we show that the ability to fly even short distances (< 100 m) between habitat fragments varies dramatically and consistently among species of forest birds, and that this variation correlates strongly with species' extinction histories and current distributions across the archipelago. This extreme variation in flight capability indicates that species' persistence in isolated forest remnants will be differentially mediated by their respective dispersal abilities, and that corridors connecting such fragments will be essential for the maintenance of avian diversity in fragmented tropical landscapes. PMID:18513315

  10. Dendritic connectivity controls biodiversity patterns in experimental metacommunities

    NASA Astrophysics Data System (ADS)

    Carrara, F.; Altermatt, F.; Rodriguez-Iturbe, I.; Rinaldo, A.

    2012-04-01

    Biological communities often occur in spatially structured habitats where connectivity directly affects dispersal and metacommunity processes. Many highly diverse landscapes exhibit hierarchical spatial structures that are shaped by geomorphological processes and riverine ecosystems, among the most diverse habitats on earth, represent an outstanding example of such mechanisms. Recent theoretical work suggests that dispersal constrained by the connectivity of specific habitat structures, such as dendrites like river networks, can explain observed features of biodiversity, but direct evidence is still lacking. Furthermore, in many environments intrinsic disturbance events contribute to spatio-temporal heterogeneity. Previous microbial experiments found that spatio-temporal heterogeneity among local communities induced by disturbance and dispersal events have a strong influence on species coexistence and biodiversity. These factors, directly affecting the history of community assembly, introduce variability in community composition in term of abundances and local species richness. We investigate the effects of directional dispersal imposed by the habitat-network structure on the biodiversity of metacommunities by conducting a laboratory experiment using aquatic microcosms. Experiments were conducted in 36-well culture plates, thus imposing by construction a metacommunity structure: each well hosted a local community within the whole landscape and dispersal occurred by periodic transfer of culture medium among connected local communities, following two different geometries. Disturbance consisted of medium replacement and reflects the spatial environmental heterogeneity inherent to many natural systems. We compared spatially heterogeneous metacommunities following a river network geometry, with spatially homogeneous metacommunities, in which every local community has 2D lattice four nearest neighbors. Local dispersal in isotropic lattice landscapes homogenizes local

  11. Quantifying the direct transfer costs of common brushtail possum dispersal using least-cost modelling: a combined cost-surface and accumulated-cost dispersal kernel approach.

    PubMed

    Etherington, Thomas R; Perry, George L W; Cowan, Phil E; Clout, Mick N

    2014-01-01

    Dispersal costs need to be quantified from empirical data and incorporated into dispersal models to improve our understanding of the dispersal process. We are interested in quantifying how landscape features affect the immediately incurred direct costs associated with the transfer of an organism from one location to another. We propose that least-cost modelling is one method that can be used to quantify direct transfer costs. By representing the landscape as a cost-surface, which describes the costs associated with traversing different landscape features, least-cost modelling is often applied to measure connectivity between locations in accumulated-cost units that are a combination of both the distance travelled and the costs traversed. However, we take an additional step by defining an accumulated-cost dispersal kernel, which describes the probability of dispersal in accumulated-cost units. This novel combination of cost-surface and accumulated-cost dispersal kernel enables the transfer stage of dispersal to incorporate the effects of landscape features by modifying the direction of dispersal based on the cost-surface and the distance of dispersal based on the accumulated-cost dispersal kernel. We apply this approach to the common brushtail possum (Trichosurus vulpecula) within the North Island of New Zealand, demonstrating how commonly collected empirical dispersal data can be used to calibrate a cost-surface and associated accumulated-cost dispersal kernel. Our results indicate that considerable improvements could be made to the modelling of the transfer stage of possum dispersal by using a cost-surface and associated accumulated-cost dispersal kernel instead of a more traditional straight-line distance based dispersal kernel. We envisage a variety of ways in which the information from this novel combination of a cost-surface and accumulated-cost dispersal kernel could be gainfully incorporated into existing dispersal models. This would enable more realistic

  12. Quantifying the Direct Transfer Costs of Common Brushtail Possum Dispersal using Least-Cost Modelling: A Combined Cost-Surface and Accumulated-Cost Dispersal Kernel Approach

    PubMed Central

    Etherington, Thomas R.; Perry, George L. W.; Cowan, Phil E.; Clout, Mick N.

    2014-01-01

    Dispersal costs need to be quantified from empirical data and incorporated into dispersal models to improve our understanding of the dispersal process. We are interested in quantifying how landscape features affect the immediately incurred direct costs associated with the transfer of an organism from one location to another. We propose that least-cost modelling is one method that can be used to quantify direct transfer costs. By representing the landscape as a cost-surface, which describes the costs associated with traversing different landscape features, least-cost modelling is often applied to measure connectivity between locations in accumulated-cost units that are a combination of both the distance travelled and the costs traversed. However, we take an additional step by defining an accumulated-cost dispersal kernel, which describes the probability of dispersal in accumulated-cost units. This novel combination of cost-surface and accumulated-cost dispersal kernel enables the transfer stage of dispersal to incorporate the effects of landscape features by modifying the direction of dispersal based on the cost-surface and the distance of dispersal based on the accumulated-cost dispersal kernel. We apply this approach to the common brushtail possum (Trichosurus vulpecula) within the North Island of New Zealand, demonstrating how commonly collected empirical dispersal data can be used to calibrate a cost-surface and associated accumulated-cost dispersal kernel. Our results indicate that considerable improvements could be made to the modelling of the transfer stage of possum dispersal by using a cost-surface and associated accumulated-cost dispersal kernel instead of a more traditional straight-line distance based dispersal kernel. We envisage a variety of ways in which the information from this novel combination of a cost-surface and accumulated-cost dispersal kernel could be gainfully incorporated into existing dispersal models. This would enable more realistic

  13. Herbivorous fishes, ecosystem function and mobile links on coral reefs

    NASA Astrophysics Data System (ADS)

    Welsh, J. Q.; Bellwood, D. R.

    2014-06-01

    Understanding large-scale movement of ecologically important taxa is key to both species and ecosystem management. Those species responsible for maintaining functional connectivity between habitats are often called mobile links and are regarded as essential elements of resilience. By providing connectivity, they support resilience across spatial scales. Most marine organisms, including fishes, have long-term, biogeographic-scale connectivity through larval movement. Although most reef species are highly site attached after larval settlement, some taxa may also be able to provide rapid, reef-scale connectivity as adults. On coral reefs, the identity of such taxa and the extent of their mobility are not yet known. We use acoustic telemetry to monitor the movements of Kyphosus vaigiensis, one of the few reef fishes that feeds on adult brown macroalgae. Unlike other benthic herbivorous fish species, it also exhibits large-scale (>2 km) movements. Individual K. vaigiensis cover, on average, a 2.5 km length of reef (11 km maximum) each day. These large-scale movements suggest that this species may act as a mobile link, providing functional connectivity, should the need arise, and helping to support functional processes across habitats and spatial scales. An analysis of published studies of home ranges in reef fishes found a consistent relationship between home range size and body length. K. vaigiensis is the sole herbivore to depart significantly from the expected home range-body size relationship, with home range sizes more comparable to exceptionally mobile large pelagic predators rather than other reef herbivores. While the large-scale movements of K. vaigiensis reveal its potential capacity to enhance resilience over large areas, it also emphasizes the potential limitations of small marine reserves to protect some herbivore populations.

  14. Quantum mechanics with a quartic dispersion law

    NASA Astrophysics Data System (ADS)

    Ruhl, Joanna

    Creation of three-dimensional matter waves, the three-dimensional analog of one-dimensional solitons, has been a goal of experimental physics for some time. A recent proposal has suggested that changing the dispersion law from quadratic to quartic for ultra cold atoms in a shaken lattice should allow for the creation of these objects. In this thesis, we develop the theoretical basis for quantum mechanics with a quartic dispersion law. The probability current functional is constructed from the corresponding time-dependent Schrodinger equation, and used to derive the junction conditions that connect the derivatives of the wavefunction on one side of a potential discontinuity to the ones on the other side. Reflection and transmission amplitudes are determined for scattering problems concerning both step potentials and rectangular barriers/wells. For sufficiently narrow barriers/wells, we show that a delta-potential constitutes a simple but reliable model for the scatterer. The scattering properties of wide barriers/wells are consistent with the predictions of the classical theory. Finally, we find the eigenstates and eigenenergies of a particle in an infinitely deep well. A simple approximate exp