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Fatty acid composition of six freshwater wild cyanobacterial species.  


Hydroxy, n-saturated, branched, dioic, and unsaturated fatty acids in six freshwater wild cyanobacteria (Chroococcus minutus, Lyngbya ceylanica, Merismopedia glauca, Nodularia sphaerocarpa, Nostoc linckia, and Synechococcus aeruginosus) collected from different lakes and springs of Israel have been identified by gas chromatography-mass spectrometry (GC-MS). PMID:12744080

Rezanka, T; Dor, I; Prell, A; Dembitsky, V M



Occurrence of toxigenic cyanobacterial blooms in freshwaters of Sri Lanka.  


A previous pioneering study of freshwater bodies in Sri Lanka revealed the presence of toxic cyanobacteria in three out of four water bodies tested. It was therefore important to perform a more detailed investigation into the presence of cyanobacteria and their toxins throughout Sri Lanka. The country has a long history of well-planned water management with the agricultural economy and drinking water supply still dependent on thousands of man-made tanks. Seventeen reservoirs from different user categories and different climatic zones were selected to study variations in phytoplankton communities with relation to major nutrients, with particular emphasis on cyanobacteria. The study was carried out during a two-year period and heavy growths or blooms of cyanobacteria observed during the study period were tested for microcystins. The results clearly categorised the 17 reservoirs into four groups parallel to the classification based on the user categories of water bodies. Biomass of total phytoplankton, the abundance of cyanobacteria, the dominance of Microcystis spp. and concentration of nitrate (N) and total phosphorous (P) were the lowest in drinking water bodies and the highest in aesthetic water bodies. Irrigation water bodies showed the second lowest values for phytoplankton biomass, and concentration of N and P, while hydropower reservoirs showed the second highest values for the same parameters. The fraction of cyanobacteria in irrigation waters was higher than that in hydropower reservoirs, but surprisingly the dominance of Microcystis spp. was reversed. Possible reasons for these variations are discussed. More than half of the bloom material tested contained microcystins up to 81microgl(-1). Our findings indicate the potential for high-risk situations due to toxigenic cyanobacterial blooms in susceptible freshwaters of Sri Lanka. PMID:16464697

Jayatissa, L P; Silva, E I L; McElhiney, J; Lawton, L A



Depth profiles of cyanobacterial hepatotoxins (microcystins) in three Turkish freshwater lakes  

Microsoft Academic Search

The Turkish freshwater lakes, Sapanca, Iznik and Taskisi (Calticak) have been enriched with nutrients from agriculture and domestic sources for many years. A major bloom of cyanobacteria (blue-green algae) in Lake Sapanca was recorded in May 1997, closely followed by a fish kill. Investigations were subsequently made on the cyanobacteria and water quality of the lakes, including analysis for cyanobacterial

Meric Albay; Reyhan Akcaalan; Huseyin Tufekci; James S. Metcalf; Kenneth A. Beattie; Geoffrey A. Codd



Accumulation of cyanobacterial toxins in freshwater "seafood" and its consequences for public health: a review.  


This review summarizes and discusses the current understanding of human exposure to cyanobacterial toxins in "seafood" collected from freshwater and coastal areas. The review consists of three parts: (a) the existing literature on concentrations of cyanobacterial toxins in seafood is reviewed, and the likelihood of bioaccumulation discussed; (b) we derive cyanotoxin doses likely to occur through seafood consumption and propose guideline values for seafood and compare these to guidelines for drinking water; and (c) we discuss means to assess, control or mitigate the risks of exposure to cyanotoxins through seafood consumption. This is discussed in the context of two specific procedures, the food specific HACCP-approach and the water-specific Water Safety Plan approach by the WHO. Risks of exposure to cyanotoxins in food are sometimes underestimated. Risk assessments should acknowledge this and investigate the partitioning of exposure between drinking-water and food, which may vary depending on local circumstances. PMID:17689845

Ibelings, Bas W; Chorus, Ingrid



Cyanobacterial toxins: risk management for health protection  

Microsoft Academic Search

This paper reviews the occurrence and properties of cyanobacterial toxins, with reference to the recognition and management of the human health risks which they may present. Mass populations of toxin-producing cyanobacteria in natural and controlled waterbodies include blooms and scums of planktonic species, and mats and biofilms of benthic species. Toxic cyanobacterial populations have been reported in freshwaters in over

Geoffrey A. Codd; Louise F. Morrison; James S. Metcalf



Competitive exclusion of Cyanobacterial species in the Great Salt Lake.  


The Great Salt Lake is separated into different salinity regimes by rail and vehicular causeways. Cyanobacterial distributions map salinity, with Aphanothece halophytica proliferating in the highly saline northern arm (27% saline), while Nodularia spumigena occurs in the less saline south (6-10%). We sought to test if cyanobacterial species abundant in the north are competitively excluded from the south, and if southern species are excluded by the high salinity of the north. Autoclaved samples from the north and south sides of each causeway were inoculated with water from each area. Aphanothece, Oscillatoria, Phormidium, and Nodularia were identified in the culture flasks using comparative differential interference contrast, fluorescence, and scanning electron microscopy. Aphanothece halophytica occurred in all inocula, but is suppressed in the presence of Nodularia spumigena. N. spumigena was found only in inocula from the less saline waters in the south, and apparently cannot survive the extremely hypersaline waters of the northern arm. These data suggest that both biotic and abiotic factors influence cyanobacterial distributions in the Great Salt Lake. PMID:19129967

Roney, Hillary C; Booth, Gary M; Cox, Paul Alan



Oxidative stress and detoxification biomarker responses in aquatic freshwater vertebrates exposed to microcystins and cyanobacterial biomass.  


Cyanobacterial blooms represent a serious threat to the aquatic environment. Among other effects, biochemical markers have been studied in aquatic vertebrates after exposures to toxic cyanobacteria. Some parameters such as protein phosphatases may serve as selective markers of exposure to microcystins, but under natural conditions, fish are exposed to complex mixtures, which affect the overall biomarker response. This review aims to provide a critical summary of biomarker responses in aquatic vertebrates (mostly fish) to toxic cyanobacteria with a special focus on detoxification and oxidative stress. Detoxification biomarkers such as glutathione (GSH) and glutathione-S-transferase (GST) showed very high variability with poor general trends. Often, stimulations and/or inhibitions and/or no effects at GSH or GST have been reported, even within a single study, depending on many variables, including time, dose, tissue, species, etc. Most of the oxidative stress biomarkers (e.g., superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) provided more consistent responses, but only lipid peroxidation (LPO) seemed to fulfill the criteria needed for biomarkers, i.e., a sufficiently long half-life and systematic response. Indeed, reviewed papers demonstrated that toxic cyanobacteria systematically elevate levels of LPO, which indicates the important role of oxidative damage in cyanobacterial toxicity. In summary, the measurement of biochemical changes under laboratory conditions may provide information on the mode of toxic action. However, comparison of different studies is very difficult, and the practical use of detoxification or oxidative stress biomarkers as diagnostic tools or early warnings of cyanobacterial toxicity is questionable. PMID:22767295

Paskerová, Hana; Hilscherová, Klára; Bláha, Lud?k



Nutrient and other environmental controls of harmful cyanobacterial blooms along the freshwater-marine continuum.  


Nutrient and hydrologic conditions strongly influence harmful planktonic and benthic cyanobacterial bloom (CHAB) dynamics in aquatic ecosystems ranging from streams and lakes to coastal ecosystems. Urbanization, agricultural and industrial development have led to increased nitrogen (N) and phosphorus (P) discharge, which affect CHAB potentials of receiving waters. The amounts, proportions and chemical composition of N and P sources can influence the composition, magnitude and duration of blooms. This, in turn, has ramifications for food web dynamics (toxic or inedible CHABs), nutrient and oxygen cycling and nutrient budgets. Some CHABs are capable of N2 fixation, a process that can influence N availability and budgets. Certain invasive N2 fixing taxa (e.g., Cylindrospermopsis, Lyngbya) also effectively compete for fixed N during spring, N-enriched runoff periods, while they use N2 fixation to supplant their N needs during N-deplete summer months. Control of these taxa is strongly dependent on P supply. However, additional factors, such as molar N:P supply ratios, organic matter availability, light attenuation, freshwater discharge, flushing rates (residence time) and water column stability play interactive roles in determining CHAB composition (i.e. N2 fixing vs. non-N2 fixing taxa) and biomass. Bloom potentials of nutrient-impacted waters are sensitive to water residence (or flushing) time, temperatures (preference for > 15 degrees C), vertical mixing and turbidity. These physical forcing features can control absolute growth rates of bloom taxa. Human activities may affect "bottom up" physical-chemical modulators either directly, by controlling hydrologic, nutrient, sediment and toxic discharges, or indirectly, by influencing climate. Control and management of cyanobacterial and other phytoplankton blooms invariably includes nutrient input constraints, most often focused on N and/or P. While single nutrient input constraints may be effective in some water bodies, dual N and P input reductions are usually required for effective long-term control and management of blooms. In some systems where hydrologic manipulations (i.e., plentiful water supplies) are possible, reducing the water residence time by flushing and artificial mixing (along with nutrient input constraints) can be effective alternatives. Blooms that are not readily consumed and transferred up the food web will form a relatively large proportion of sedimented organic matter. This, in turn, will exacerbate sediment oxygen demand, and enhance the potential for oxygen depletion and release of nutrients back to the water column. This scenario is particularly problematic in long-residence time (i.e., months) systems, where blooms may exert a strong positive feedback on future events. Implications of these scenarios and the confounding issues of climatic (hydrologic) variability, including droughts, tropical storms, hurricanes and floods, will be discussed in the context of developing effective CHAB control strategies along the freshwater-marine continuum. PMID:18461771

Paerl, Hans



Toxic cyanobacterial cells containing microcystins induce oxidative stress in exposed tilapia fish ( Oreochromis sp.) under laboratory conditions  

Microsoft Academic Search

The effects of microcystins from cyanobacterial cells on various oxidative stress biomarkers in liver, kidney and gill tissues in freshwater tilapia fish (Oreochromis sp.) were investigated under laboratory conditions. Microcystins are a family of cyclic peptide toxins produced by species of freshwater cyanobacteria (blue-green algae). Fish were exposed to the cyanobacterial cells in two ways: mixed with a commercial fish

Ángeles Jos; Silvia Pichardo; Ana I. Prieto; Guillermo Repetto; Carmen M. Vázquez; Isabel Moreno; Ana M. Cameán



Relation between primary liver cancer occurrence and freshwater Cyanobacterial blooms in Serbia  

NASA Astrophysics Data System (ADS)

Since 1980 cyanobacterial blooms occurred in a large number of reservoirs, lakes and running water ecosystems (rivers and channels) in Serbia. Among 49 reservoirs examined, 32 were found in blooming condition almost every year during last 2 decades. All natural lakes and 12 river and channel localities in Vojvodina province (agricultural part) proved to be sites with cyanobacterial proliferation. The part of Central Serbia is very problematic for ground water supply. For that reason 21 reservoirs serve as drinking water suppliers. Significant and persistant cyanobacterial blooms have been recognized in 9 of them. Samples for cyanotoxin analyses were taken during and after blooms in Celije Reservoir and in drinking water in Krusevac town 2 days later. Concentratins of Microcystin-LR were 460 µg•L-1 and for Microcystin-RR 170 µg•L-1. Drinking water contained 2 and 0.6 µg•L-1, respectively. Serbia consists of 30 administrative units, in three of which studies for Primary Liver Cancer (PLC) were conducted independently: Vojvodina, where drinking-water is supplied only from deep wells where 7 regions were studied, Kosovo with a few high mountain reservoirs for water supply without cyanobacterial proliferation where 6 regions were studied, and Central Serbia, where 17 regions were studied. Central Serbia showed 7 regions with extremly high PLC incidence and 8 regions with lower PLC incidence. In the two investigated periods, the high PLC mortality of 11.6 in 1980-1995 and extremely high PLC incidence of 26 in 2000 was observed in the regions affected by heavy cyanobacterial blooms. In contrast, the regions not affected by the blooms, PLC mortality and incidence rates were substantially lower: from 1980-1995 mortality rate ammounted to 2.7 in Kosovo, 7.6 in Vojvodina, and 8.5 in the non-affected regions of Central Serbia, and in 2000 incidence rate ammounted to 4.1 (Kosovo), 6.6 (Vojvodina), and 7.5 in the non-affected regions of Central Serbia. The uneven geographic distribution of liver cancer is conspicuous, and „hot spots" could be related to drinking water supply. It is very clear that PLC high risk regions correspond with cyanobacterial blooming and PLC low risks regions correspond with water supplies not affected by cyanobacteria. PLC incidence in all regions not affected by cyanobacteria, i.e. Vojvodina, Kosovo and some regions in Central Serbia are in a similar range, whereas it is significantly higher in the affected regions of Central Serbia.

Svir?ev, Z.; Miladinov-Mikov, M.; Simeunovi?, J.; Vidovi?, M.; Stojanovi?, D.



Nutrient and other environmental controls of harmful cyanobacterial blooms along the freshwater–marine continuum  

Microsoft Academic Search

Nutrient and hydrologic conditions strongly influence harmful planktonic and benthic cyanobacterial bloom (CHAB) dynamics\\u000a in aquatic ecosystems ranging from streams and lakes to coastal ecosystems. Urbanization, agricultural and industrial development\\u000a have led to increased nitrogen (N) and phosphorus (P) discharge, which affect CHAB potentials of receiving waters. The amounts,\\u000a proportions and chemical composition of N and P sources can influence

Hans Paerl


Detection of various freshwater cyanobacterial toxins using ultra-performance liquid chromatography tandem mass spectrometry.  


Several freshwater cyanobacteria species have the capability to produce toxic compounds, frequently referred to as cyanotoxins. The most prevalent of these cyanotoxins is microcystin LR. Recognizing the potential health risk, France, Italy, Poland, Australia, Canada, and Brazil have set either standards or guidelines for the amount of microcystin LR permissible in drinking water based on the World Health Organization guideline of one microg/L of microcystin LR. Recently, the United States Environmental Protection Agency has begun to evaluate the occurrence and health effects of cyanotoxins and their susceptibility to water treatment under the Safe Drinking Water Act through the Contaminant Candidate List (CCL). A recent update of the Contaminant Candidate List focuses research and data collection on the cyanotoxins microcystin LR, anatoxin-a, and cylindrospermopsin. Liquid Chromatography/Tandem-Mass Spectrometry (LC/MS/MS) is a powerful tool for the analysis of various analytes in a wide variety of matrices because of its sensitivity and selectivity. The use of smaller column media (sub 2 microm particles) was investigated to both improve the speed, sensitivity and resolution, and to quantify the CCL cyanotoxins, in a single analysis, using Ultra-Performance Liquid Chromatography (UPLC) combined with tandem mass spectrometry. Natural waters and spiked samples were analyzed to show proof-of-performance. The presented method was able to clearly resolve each of the cyanotoxins in less than eight minutes with specificity and high spike recoveries. PMID:19878689

Oehrle, Stuart A; Southwell, Ben; Westrick, Judy



Cyanobacterial toxins: a qualitative meta-analysis of concentrations, dosage and effects in freshwater, estuarine and marine biota.  


This paper reviews the rapidly expanding literature on the ecological effects of cyanobacterial toxins. The study employs a qualitative meta-analysis from the literature examining results from a large number of independent studies and extracts general patterns from the literature or signals contradictions. The meta-analysis is set up by putting together two large tables--embodying a large and representative part of the literature (see Appendix A). The first table (Table A.1) reviews the presence (concentrations) of different cyanobacterial toxins in the tissues of various groups of aquatic biota after exposure via different routes, experimentally in the lab or via natural routes in the environment. The second table (Table A.2) reviews the dose dependent effect of toxins on biota. The great majority of studies deal with the presence and effects of microcystin, especially of the MC-LR congener. Although this may partly be justified--MC-LR is an abundant and highly toxic protein--our review also emphasizes what is known about (i) other MC congeners (a number of studies showed a preferred accumulation of the less toxic variant MC-RR in animal tissues), (ii) nodularin (data on a range of biota from studies on the Baltic Sea), (iii) neurotoxins like anatoxin-a(s), which are conspicuously often present at times when mass mortalities of birds occur, (iv) a few studies on the presence and effects of cylindrospermposin, as well as (v) the first examples of ecological effects of newly identified bioactive compounds, like microviridin-J. Data were reorganized to assess to what extent bioconcentration (uptake and concentration of toxins from the water) or biomagnification (uptake and concentration via the food) of cyanobacterial toxins occurs in ecosystems. There is little support for the occurrence of biomagnification, and this reduces the risk for biota at higher trophic levels. Rather than biomagnification biodilution seems to occur in the foodweb with toxins being subject to degradation and excretion at every level. Nevertheless toxins were present at all tropic levels, indicating that some vectorial transport must take place, and in sufficient quantities for effects to possibly occur. Feeding seemed to be the most important route for exposure of aquatic biota to cyanobacterial toxins. A fair number of studies focus on dissolved toxins, but in those studies purified toxin typically is used, and biota do not appear very sensitive to this form of exposure. More effects are found when crude cyanobacterial cell lysates are used, indicating that there may be synergistic effects between different bioactive compounds. Aquatic biota are by no means defenseless against toxic cyanobacteria. Several studies indicate that those species that are most frequently exposed to toxins in their natural environment are also the most tolerant. Protection includes behavioral mechanisms, detoxication of MC and NODLN by conjugation with glutathione, and fairly rapid depuration and excretion. A common theme in much of the ecological studies is that of modulating factors. Effects are seldom straightforward, but are dependent on factors like the (feeding) condition of the animals, environmental conditions and the history of exposure (acclimation and adaptation to toxic cyanobacteria). This makes it harder to generalize on what is known about ecological effects of cyanobacterial toxins. The paper concludes by summarizing the risks for birds, fish, macroinvertebrates and zooplankton. Although acute (lethal) effects are mentioned in the literature, mass mortalities of--especially--fish are more likely to be the result of multiple stress factors that co-occur during cyanobacterial blooms. Bivalves appear remarkably resistant, whilst the harmful effects of cyanobacteria on zooplankton vary widely and the specific contribution of toxins is hard to evaluate. PMID:18461789

Ibelings, Bas W; Havens, Karl E




Microsoft Academic Search

Abstract—There is generally a lack of saltwater ecotoxicity data for risk assessment purposes, leaving an unknown margin of uncertainty in saltwater assessments that utilize surrogate freshwater data. Consequently, a need for sound scientific advice on the suitability of using freshwater data to extrapolate to saltwater effects exists. Here we use species sensitivity distributions to determine if freshwater datasets are adequately

James R. Wheeler; Kenneth M. Y. Leung; David Morritt; Neal Sorokin; Howard Rogers; Robin Toy; Martin Holt; Paul Whitehouse; Mark Crane



UV-induced photochemical heterogeneity of dissolved and attached organic matter associated with cyanobacterial blooms in a eutrophic freshwater lake.  


Cyanobacterial blooms represent a significant ecological and human health problem worldwide. In aquatic environments, cyanobacterial blooms are actually surrounded by dissolved organic matter (DOM) and attached organic matter (AOM) that bind with algal cells. In this study, DOM and AOM fractionated from blooming cyanobacteria in a eutrophic freshwater lake (Lake Taihu, China) were irradiated with a polychromatic UV lamp, and the photochemical heterogeneity was investigated using fluorescence excitation-emission matrix (EEM)-parallel factor (PARAFAC) analysis and synchronous fluorescence (SF)-two dimensional correlation spectroscopy (2DCOS). It was shown that a 6-day UV irradiation caused more pronounced mineralization for DOM than AOM (59.7% vs. 41.9%). The EEM-PARAFAC analysis identified one tyrosine-, one humic-, and two tryptophan-like components in both DOM and AOM, and high component photodegradation rates were observed for DOM versus AOM (k > 0.554 vs. <0.519). Moreover, SF-2DCOS found that the photodegradation of organic matters followed the sequence of tyrosine-like > humic-like > tryptophan-like substances. Humic-like substances promoted the indirect photochemical reactions, and were responsible for the higher photochemical rate for DOM. The lower photodegradation of AOM benefited the integrality of cells in cyanobacterial blooms against the negative impact of UV irradiation. Therefore, the photochemical behavior of organic matter was related to the adaptation of enhanced-duration cyanobacterial blooms in aquatic environments. PMID:24041526

Xu, Huacheng; Jiang, Helong



Species invasions and the changing biogeography of Australian freshwater fishes  

Microsoft Academic Search

Aim By dissolving natural physical barriers to movement, human-mediated species introductions have dramatically reshuffled the present-day biogeography of freshwater fishes. The present study investigates whether the antiquity of Australia's freshwater ichthyofauna has been altered by the widespread invasion of non-indigenous fish species. Location Australia.

Julian D. Olden; Mark J. Kennard; Bradley J. Pusey



Genetic calibration of species diversity among North America's freshwater fishes  

PubMed Central

Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a more accessible molecular identification key for its application, we generated a standard reference library of mtDNA sequences (DNA barcodes) derived from expert-identified museum specimens for 752 North American freshwater fish species. This study demonstrates that 90% of known species can be delineated using barcodes. Moreover, it reveals numerous genetic discontinuities indicative of independently evolving lineages within described species, which points to the presence of morphologically cryptic diversity. From the 752 species analyzed, our survey flagged 138 named species that represent as many as 347 candidate species, which suggests a 28% increase in species diversity. In contrast, several species of parasitic and nonparasitic lampreys lack such discontinuity and may represent alternative life history strategies within single species. Therefore, it appears that the current North American freshwater fish taxonomy at the species level significantly conceals diversity in some groups, although artificially creating diversity in others. In addition to providing an easily accessible digital identification system, this study identifies 151 fish species for which taxonomic revision is required.

April, Julien; Mayden, Richard L.; Hanner, Robert H.; Bernatchez, Louis



Bioaccumulation of Heavy Metals in Freshwater Fish Species, Anzali, Iran  

Microsoft Academic Search

The main objectives of study were to monitor the metals concentrations, in freshwater fish species, Carassius gibelio and Esox lucius; and to identify any relationships between species and bioaccumulation of metals. The highest concentration of metals (cadmium,\\u000a 1.96; copper, 24.2; zinc, 49.6; lead, 5.4; chromium, 4.4) between the fish species and tissues was in the liver of Esox lucius, while

Mohammad Ebrahimpour; Alireza Pourkhabbaz; Rahimeh Baramaki; Hadi Babaei; Mohammadreza Rezaei


Cyanobacterial toxins: a qualitative meta–analysis of concentrations, dosage and effects in freshwater, estuarine and marine biota  

Microsoft Academic Search

This paper reviews the rapidly expanding literature on the ecological effects of cyanobacterial toxins. The study employs\\u000a a qualitative meta–analysis from the literature examining results from a large number of independent studies and extracts\\u000a general patterns from the literature or signals contradictions. The meta–analysis is set up by putting together two large\\u000a tables – embodying a large and representative part

Bas W Ibelings; Karl E Havens



Priority management actions for alien freshwater fish species in Australia  

Microsoft Academic Search

In Australia, alien freshwater fish are continuing to steadily increase in number of species (reported in this paper to be 43), abundance, and distribution. In general however, their impacts are not well quantified in either environmental or economic terms and current management to reduce their impacts is limited and lacking direction. Although carp Cyprinus carpio have received some attention, very

John D. Koehn; Rachel F. MacKenzie



The Proximate and Lipid Composition of Several Species of Freshwater Fishes.  

National Technical Information Service (NTIS)

In conjunction with the current research at Cornell University concerned with developing foods from freshwater fish species, a systematic study of the proximate composition and the detailed lipid and fatty-acid composition of several freshwater species in...

J. E. Kinsella J. L. Shimp J. Mai



Sponge cytogenetics - mitotic chromosomes of ten species of freshwater sponge.  


Porifera (sponges) are the most basal phylum of extant metazoans. To gain insight into sponge genome construction, cytogenetic analysis was performed for ten freshwater sponge species of six genera, using conventional Giemsa staining, chromosome banding, and fluorescence in-situ hybridization. The karyotypes were very similar among the ten species, exhibiting a diploid chromosome number of 2n=46 or 48, and usually consisted of microchromosomes with one or two pairs of large chromosomes. The 18S-28S rRNA genes were localized to a single pair of microchromosomes in two Ephydatia species. Hybridization signals of the telomere (TTAGGG)n sequences were observed at the ends of metaphase chromosomes. The genome sizes of Ephydatia fluviatilis and Ephydatia muelleri were estimated by flow cytometric analysis as about 0.7 pg per diploid complement. These freshwater sponge species appear to represent a fairly homogeneous group with respect to karyotypes. PMID:18558800

Ishijima, Junko; Iwabe, Naoyuki; Masuda, Yoshiki; Watanabe, Yoko; Matsuda, Yoichi



Differential Sensitivity of a Coccal Green Algal and a Cyanobacterial Species to Dissolved Natural Organic Matter (NOM) (8 pp)  

Microsoft Academic Search

Background  and Aim. In non-eutrophicated freshwaters, humic substances (HS) pose chemical stresses on aquatic organisms and, hence, separating\\u000a sensitive from less sensitive or even tolerant species. One of the stresses, identified so far, is the reduction of photosynthetic\\u000a oxygen production and reduction in growth in freshwater macrophytes and algae. In a previous paper, it has been shown that\\u000a even closely related

Almut Heinrich; Christian E. W. Steinberg



Diurnal variations in the photosynthesis-respiration activity of a cyanobacterial bloom in a freshwater dam reservoir: an isotopic study  

Microsoft Academic Search

The stable isotopic analyses of molecular oxygen dissolved in water (delta(18)O(DO)) and dissolved inorganic carbon (delta(13)C(DIC)), supplemented with basic chemical measurements, have been carried out on a diurnal basis to better understand the dynamics of photosynthesis and respiration in freshwater systems. Our observations have been carried out in a lowland dam reservoir, the Sulejow Lake (central Poland), during the summer

Adriana Trojanowska; Dominika Lewicka-Szczebak; M. O. Jedrysek; Marta Kurasiewicz; Leonard I. Wassenaar; Katarzyna Izydorczyk



Bioaccumulation of heavy metals in freshwater fish species, Anzali, Iran.  


The main objectives of study were to monitor the metals concentrations, in freshwater fish species, Carassius gibelio and Esox lucius; and to identify any relationships between species and bioaccumulation of metals. The highest concentration of metals (cadmium, 1.96; copper, 24.2; zinc, 49.6; lead, 5.4; chromium, 4.4) between the fish species and tissues was in the liver of Esox lucius, while the lowest (cadmium,0.21; copper,7.2; zinc,19.4; lead,0.9; chromium,0.6 ?g/g) found in the muscle of Carassius gibelio. Results showed that the metal concentrations were in fishes in descending order of zinc > copper > lead > chromium > cadmium, similarly in the tissue liver > kidney > gill ~ intestine > muscle. PMID:21858708

Ebrahimpour, Mohammad; Pourkhabbaz, Alireza; Baramaki, Rahimeh; Babaei, Hadi; Rezaei, Mohammadreza



Next generation planar waveguide detection of microcystins in freshwater and cyanobacterial extracts, utilising a novel lysis method for portable sample preparation and analysis.  


The study details the development of a fully validated, rapid and portable sensor based method for the on-site analysis of microcystins in freshwater samples. The process employs a novel lysis method for the mechanical lysis of cyanobacterial cells, with glass beads and a handheld frother in only 10 min. The assay utilises an innovative planar waveguide device that, via an evanescent wave excites fluorescent probes, for amplification of signal in a competitive immunoassay, using an anti-microcystin monoclonal with cross-reactivity against the most common, and toxic variants. Validation of the assay showed the limit of detection (LOD) to be 0.78 ng mL(-1) and the CC? to be 1 ng mL(-1). Robustness of the assay was demonstrated by intra- and inter-assay testing. Intra-assay analysis had % C.V.s between 8 and 26% and recoveries between 73 and 101%, with inter-assay analysis demonstrating % C.V.s between 5 and 14% and recoveries between 78 and 91%. Comparison with LC-MS/MS showed a high correlation (R(2)=0.9954) between the calculated concentrations of 5 different Microcystis aeruginosa cultures for total microcystin content. Total microcystin content was ascertained by the individual measurement of free and cell-bound microcystins. Free microcystins can be measured to 1 ng mL(-1), and with a 10-fold concentration step in the intracellular microcystin protocol (which brings the sample within the range of the calibration curve), intracellular pools may be determined to 0.1 ng mL(-1). This allows the determination of microcystins at and below the World Health Organisation (WHO) guideline value of 1 ?g L(-1). This sensor represents a major advancement in portable analysis capabilities and has the potential for numerous other applications. PMID:23498128

Devlin, Shauna; Meneely, Julie P; Greer, Brett; Greef, Charles; Lochhead, Michael J; Elliott, Christopher T



Investigation of a Microcystis aeruginosa cyanobacterial freshwater harmful algal bloom associated with acute microcystin toxicosis in a dog.  


Microcystin poisoning was diagnosed in a dog exposed to a Microcystis aeruginosa-dominated, freshwater, harmful algal bloom at Milford Lake, Kansas, which occurred during the summer of 2011. Lake water microcystin concentrations were determined at intervals during the summer, using competitive enzyme-linked immunosorbent assays, and indicated extremely high, localized microcystin concentrations of up to 126,000 ng/ml. Multiple extraction and analysis techniques were used in the determination of free and total microcystins in vomitus and liver samples from the poisoned dog. Vomitus and liver contained microcystins, as determined by enzyme-linked immunosorbent assays, and the presence of microcystin-LR was confirmed in vomitus and liver samples using liquid chromatography coupled with tandem mass spectrometry. Major toxic effects in a dog presented for treatment on the day following exposure included fulminant liver failure and coagulopathy. The patient deteriorated rapidly despite aggressive treatment and was euthanized. Postmortem lesions included diffuse, acute, massive hepatic necrosis and hemorrhage, as well as acute necrosis of the renal tubular epithelium. A diagnosis of microcystin poisoning was based on the demonstration of M. aeruginosa and microcystin-LR in the lake water, as well as in vomitus produced early in the course of the poisoning; the presence of microcystin-LR in liver tissue; and a typical clinical course including gastroenteritis and fulminant liver failure. PMID:22604771

van der Merwe, Deon; Sebbag, Lionel; Nietfeld, Jerome C; Aubel, Mark T; Foss, Amanda; Carney, Edward



Selenium species and their distribution in freshwater fish from Argentina.  


The distribution and speciation of selenium (Se) in freshwater fish (muscle and liver tissue) from lakes in Argentina was investigated. Three introduced species, brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis), and one native species, creole perch (Percichthys trucha), were investigated. Values for total selenium in muscle ranged from 0.66 to 1.61 ?g/g, while in the liver, concentrations were much higher, from 4.46 to 73.71 ?g/g on a dry matter basis. Separation of soluble Se species (SeCys(2), selenomethionine (SeMet), SeMeSeCys, selenite and selenate) was achieved by ion exchange chromatography and detection was performed by inductively coupled plasma-mass spectrometry. The results showed that in fish muscle, from 47 to 55 % of selenium was soluble and the only Se species identified was SeMet, which represented around 80 % of soluble Se, while in the liver, the amount of soluble Se ranged from 61 to 76 % and the percentage of species identified (SeMet and SeCys(2)) was much lower and ranged from 8 to 17 % of soluble Se. PMID:23242863

Kristan, Urška; Arribére, María A; Stibilj, Vekoslava



Species diversity of freshwater hyphomycetes in some streams of Pakistan. III. Autumnal colonization of freshwater hyphomycetes on bait leaves  

Microsoft Academic Search

Significantly more species of freshwater hyphomycetes colonized bait leaves of alder (16 species) and willow (14 species)\\u000a during early submersion period (1 wk) than those of oak (8 species). Production of conidia was also higher on alder and willow\\u000a leaves than on oak leaves. Higher amounts of dry mass were lost from the alder (28.6%) and willow leaves (29.4%) than

Syed Hussain Iqbal



Extensive allozyme monomorphism in a threatened species of freshwater mussel, Margaritifera hembeli Conrad (Bivalvia: Margaritiferidae)  

Microsoft Academic Search

A threatened but under-studied component offreshwater biodiversity in North America is thenative freshwater mussels (Bivalvia:Unionoidea: Margaritiferidae and Unionidae). Genetic data suggest that these mussel speciesgenerally exhibit levels of variability similarto other invertebrates. We surveyed allozymevariation in the Louisiana Pearlshell, Margaritifera hembeli (Margaritiferidae), athreatened freshwater mussel. Five examinedpopulations are monomorphic for 25 allozymeloci, the first report of a native freshwatermussel species

Jason P. Curole; David W. Foltz; Kenneth M. Brown



Three new Procamallanus (Spirocamallanus) species from freshwater fishes in Mexico.  


The following 3 new species of Procamallanus (Spirocamallanus) are described from the intestines of freshwater fishes in Mexico, all belonging to the morphological group characterized by the presence of wide caudal alae, 3 pairs of subventral preanal papillae, and unequal spicules in the male: Procamallanus (Spirocamallanus) jaliscensis n. sp. (type host: Agonostomus monticola) and Procamallanus (Spirocamallanus) gobiomori n. sp. (hosts: Gobiomorus maculatus [type host], Gobiomorus polylepis and Eleotris picta) from 2 rivers in Jalisco State, western Mexico, and Procamallanus (Spirocamallanus) mexicanus n. sp. (type host: Cichlasoma geddesi) from Xalapa District, Veracruz State (Gulf of Mexico region), southeastern Mexico. Procamallanus jaliscensis is characterized by the length of the spicules (606-900 microm and 282-354 microm), number (15-16) of spiral ridges in the buccal capsule, and the digit-like protrusion with 1 terminal cuticular spike on the female tail; P. mexicanus by the length of the spicules (456-480 microm and 231-233 microm), number (10-12) of spiral ridges in the capsule, and the shape of the female tail (conical with a suddenly narrowed distal part, without any terminal spikes); and P. gobiomori by the length of spicules (318-348 microm and 156-192 microm), number (8-10) of spiral ridges and by the digit-like protrusion with 2 terminal cuticular spikes on the female tail. PMID:10701574

Moravec, F; Salgado-Maldonado, G; Caspeta-Mandujano, J



A new genus and species of freshwater monostiliferous hoplonemertean (Nemertea, Enopla) from the People's Republic of China  

Microsoft Academic Search

A new genus and species of freshwater monostiliferous hoplonemertean, Limnemertes poyangensis gen. et sp. nov., from Poyang Lake, People's Republic of China, is described and illustrated. The taxon is compared and contrasted with previously described freshwater hoplonemerteans. This is the fourth species of freshwater nemertean to be described from China and the first recorded from Poyang Lake.

Ray Gibson; Hongzhu Wang



Predicting impact of freshwater exotic species on native biodiversity: Challenges in spatial scaling  

Microsoft Academic Search

Global homogenization of biota is underway through worldwide introduction and establishment of nonindigenous (exotic) species. Freshwater ecologists should devote more attention to exotic species for two reasons. First, exotics provide an opportunity to test hypotheses about what characteristics of species or habitats are related to successful establishment or invasibility, respectively. Second, predicting which species will cause large ecological change is





Microsoft Academic Search

Two new freshwater species of the genus Jesogammarus collected from north China are reported. Jesogammarus (J.) fontanus, new species, is diagnosed by mandibular palp article 1 with three distal spines and uropod 3 foliaceous. Jesogammarus (J.) hebeiensis , new species, differs from the congeneric species in mandibular palp article 1 with two to three distal spines, uropod 3 lanceolate and

Zhong-E Hou; Shuqiang Li


Influence of toxic cyanobacteria on community structure and microcystin accumulation of freshwater molluscs  

Microsoft Academic Search

Community structure and microcystin accumulation of freshwater molluscs were studied before and after cyanobacterial proliferations, in order to assess the impact of toxic blooms on molluscs and the risk of microcystin transfer in food web. Observed decrease in mollusc abundance and changes in species richness in highly contaminated waters were not significant; however, relative abundances of taxa (prosobranchs, pulmonates, bivalves)

Claudia Gérard; Virginie Poullain; Emilie Lance; Anthony Acou; Luc Brient; Alexandre Carpentier



Hepatotoxic Cyanobacteria: A Review of the Biological Importance of Microcystins in Freshwater Environments  

Microsoft Academic Search

Cyanobacteria possess many adaptations to develop population maxima or “blooms” in lakes and reservoirs. A potential consequence of freshwater blooms of many cyanobacterial species is the production of potent toxins, including the cyclic hepatotoxins, microcystins (MCs). Approximately 70 MC variants have been isolated. Their toxicity to humans and other animals is well studied, because of public health concerns. This review

Ronald W. Zurawell; Huirong Chen; Janice M. Burke; Ellie E. Prepas




EPA Science Inventory

Riverine freshwater mussel species can be found in highly diverse communities where many similar species coexist. Mussel species potentially compete for food and space as adults, and for fish host resources during the larval (glochidial) stage. Resource partitioning at the larv...


Acute toxicity of vanadium to two species of freshwater fish  

Microsoft Academic Search

Recent studies have shown that vanadium, along with other less well known trace metals, is being introduced into the marine environment in quantities sufficient to allow for a significant bioaccumulation of the metal in the bodies of shellfish (PESCH et al. 1977). In addition, significant amounts are also entering freshwater and estuarine systems (DREHER 1977, JAFFE and WALTERS 1977). JERNELOV

Bruce K. Knudtson



The freshwater snails (Gastropoda) of Iran, with descriptions of two new genera and eight new species  

PubMed Central

Abstract Using published records and original data from recent field work and revision of Iranian material of certain species deposited in the collections of the Natural History Museum Basel, the Zoological Museum Berlin, and Natural History Museum Vienna, a checklist of the freshwater gastropod fauna of Iran was compiled. This checklist contains 73 species from 34 genera and 14 families of freshwater snails; 27 of these species (37%) are endemic to Iran. Two new genera, Kaskakia and Sarkhia, and eight species, i.e., Bithynia forcarti, Bithynia starmuehlneri, Bithynia mazandaranensis, Pseudamnicola georgievi, Kaskakia khorrasanensis, Sarkhia sarabensis, Valvata nowsharensis and Acroloxus pseudolacustris are described as new to science; Ecrobia grimmi (Clessin & Dybowski, 1888), Heleobia dalmatica (Radoman, 1974) and Hippeutis complanatus (Linnaeus, 1758) are reported for the first time from Iran. Additional field work is highly desirable for a more appropriate evaluation of the extant freshwater snail biodiversity in Iran.

Gloer, Peter; Pesic, Vladimir



Studies on the Population Dynamics and Physiological Ecology of Four Species of Fresh-Water Isopods.  

National Technical Information Service (NTIS)

The comparative biology of four species of fresh-water isopods was investigated. Isopods are known to be part of the 'pollution fauna' that can inhabit badly polluted areas. The species studies inhabit a temporaty pond, a drainage ditch, a small permanent...

A. J. Seidenberg S. C. Kendeigh



Two New Species of Camallanus (Nematoda: Camallanidae) From Freshwater Turtles in Queensland, Australia  

Microsoft Academic Search

We describe 2 new species of Camallanus (Nematoda: Camallanidae) from freshwater turtles collected in Queensland, Australia: Camallanus nithoggi n. sp. from Elseya latisternum (Gray) and Camallanus waelhreow n. sp. from Emydura krefftii (Gray), Emydura macquarrii (Gray), and Em. macquarrii dharra Cann. The only Camallanus sp. previously reported from turtles is C. chelonius Baker, 1983 (all other species in the family

Mark C. Rigby; Reuben S. K. Sharma; Ryan F. Hechinger; Thomas R. Platt; James C. Weaver



Concurrent invaders—four exotic species of Monogenea now established on exotic freshwater fishes in Australia  

Microsoft Academic Search

Four species of exotic monogeneans are reported from five species of exotic freshwater fish in Australia: Gyrodactylus bullatarudis from Poecilia reticulata and Xiphophorus helleri in Queensland; Gyrodactylus macracanthus from Misgurnus anguillicaudatus in the Australian Capital Territory; Dactylogyrus extensus from Cyprinus carpio in the Australian Capital Territory; and Dactylogyrusanchoratus from Carassius auratus in the Australian Capital Territory. This is the first

Alistair D. M Dove; Ingo Ernst



Three New Species of Rhinebothrium (Cestoda: Tetraphyllidea) from the Freshwater Whipray, Himantura chaophraya, in Malaysian Borneo  

Microsoft Academic Search

Three new Rhinebothrium Linton, 1890 species, R. kinabatanganensis n. sp., R. megacanthophallus n. sp., and R. abaiensis n. sp., collected from the spiral intestines of 6 freshwater whiprays (Himantura chaophraya, Dasyatidae) in the Kinabatangan River, Malaysian Borneo, are described. This is the first record of cestodes from the Kinabatangan River and from H. chaophraya. The new Rhinebothrium species are differentiated

Claire J. Healy



Monitoring approaches for a toxic cyanobacterial bloom.  


Cyanobacterial blooms, dominated by Microcystis sp. and associated microcystin variants, have been implicated in illnesses of humans and animals. Little is known regarding the formation of blooms and the presence of cyanotoxin variants in water bodies. Furthermore, the role played by ecological parameters, in regulating Microcystis blooms is complicate and diverse. Local authorities responsible for water management are often faced with the challenging task of dealing with cyanobacterial blooms. Therefore, the development of suitable monitoring approaches to characterize cyanobacterial blooms is an important goal. Currently, various biological, biochemical and physicochemical methods/approaches are being used to monitor cyanobacterial blooms and detect microcystins in freshwater bodies. Because these methods can vary as to the information they provide, no single approach seemed to be sufficient to accurately monitor blooms. For example, immunosensors are more suited for monitoring the presence of toxins in clear water bodies while molecular methods are more suited to detect potentially toxic strains. Thus, monitoring approaches should be tailored for specific water bodies using methods based on economic feasibility, speed, sensitivity and field applicability. This review critically evaluates monitoring approaches that are applicable to cyanobacterial blooms, especially those that focus on the presence of Microcystis, in freshwater bodies. Further, they were characterized and ranked according to their cost, speed, sensitivity and selectivity. Suggested improvements were offered as well as future research endeavors to accommodate anticipated environmental changes. PMID:23865979

Srivastava, Ankita; Singh, Shweta; Ahn, Chi-Yong; Oh, Hee-Mock; Asthana, Ravi Kumar



Cyanobacterial ecotypes in the microbial mat community of Mushroom Spring (Yellowstone National Park, Wyoming) as species-like units linking microbial community composition, structure and function  

PubMed Central

We have investigated microbial mats of alkaline siliceous hot springs in Yellowstone National Park as natural model communities to learn how microbial populations group into species-like fundamental units. Here, we bring together empirical patterns of the distribution of molecular variation in predominant mat cyanobacterial populations, theory-based modelling of how to demarcate phylogenetic clusters that correspond to ecological species and the dynamic patterns of the physical and chemical microenvironments these populations inhabit and towards which they have evolved adaptations. We show that putative ecotypes predicted by the theory-based model correspond well with distribution patterns, suggesting populations with distinct ecologies, as expected of ecological species. Further, we show that increased molecular resolution enhances our ability to detect ecotypes in this way, though yet higher molecular resolution is probably needed to detect all ecotypes in this microbial community.

Ward, David M; Bateson, Mary M; Ferris, Michael J; Kuhl, Michael; Wieland, Andrea; Koeppel, Alex; Cohan, Frederick M



Ciliate biogeography in Antarctic and Arctic freshwater ecosystems: endemism or global distribution of species?  


Ciliate diversity was investigated in situ in freshwater ecosystems of the maritime (South Shetland Islands, mainly Livingston Island, 63 degrees S) and continental Antarctic (Victoria Land, 75 degrees S), and the High Arctic (Svalbard, 79 degrees N). In total, 334 species from 117 genera were identified in both polar regions, i.e. 210 spp. (98 genera) in the Arctic, 120 spp. (73 genera) in the maritime and 59 spp. (41 genera) in the continental Antarctic. Forty-four species (13% of all species) were common to both Arctic and Antarctic freshwater bodies and 19 spp. to both Antarctic areas (12% of all species). Many taxa are cosmopolitans but some, e.g. Stentor and Metopus spp., are not, and over 20% of the taxa found in any one of the three areas are new to science. Cluster analysis revealed that species similarity between different biotopes (soil, moss) within a study area was higher than between similar biotopes in different regions. Distinct differences in the species composition of freshwater and terrestrial communities indicate that most limnetic ciliates are not ubiquitously distributed. These observations and the low congruence in species composition between both polar areas, within Antarctica and between high- and temperate-latitude water bodies, respectively, suggest that long-distance dispersal of limnetic ciliates is restricted and that some species have a limited geographical distribution. PMID:17313584

Petz, Wolfgang; Valbonesi, Alessandro; Schiftner, Uwe; Quesada, Antonio; Cynan Ellis-Evans, J




EPA Science Inventory

Short-term lethality tests were conducted with five (waste oil, No. 1 fuel oil, No. 2 fuel oil, mixed blend sweet crude oil, Lloydminister crude oil) oils and four freshwater species. The oils were tested as floating layers, emulsions, and as the water-soluble fraction of 10% oil...


Species diversity and abundance of freshwater fishes in irrigation ditches around rice fields  

Microsoft Academic Search

The relationships between environmental variables, distribution of freshwater fishes and their diet were investigated at 40 sites on irrigation ditches for rice fields in central Japan. Multivariate analyses showed that fish species richness and diversity in ditches was high when fishes were able to easily invade the rice fields. Natural stream beds not covered by concrete had greater total number

Osamu Katano; Kazumi Hosoya; Kei'ichiroh Iguchi; Motoyoshi Yamaguchi; Yoshimasa Aonuma; Satoshi Kitano




Microsoft Academic Search

The highly invasive New Zealand mudsnail, Potamopyrgus antipodarum, may compete with and displace native North American macroinvertebrates in freshwater systems wherever it becomes established. Densities and spatial distributions of 3 snail species including P. antipodarum and the threatened Taylorconcha serpenticola were compared among 3 adjacent habitat types (run, edge, and vegetation) in Banbury Springs, a tributary of the Snake River,

David C. Richards; L. Dianne Cazier; Gary T. Lester


A new species of Gieysztoria (Platyhelminthes; Rhabdocoela; Dalyelliidae) from a freshwater lake in Queensland, Australia  

Microsoft Academic Search

A new species of Dalyelliidae, Gieysztoria queenslandica, is described from a freshwater lake in Brisbane, Queensland, Australia. Gieysztoria queenslandica n. sp. is a member of the Aequales group of Gieysztoria and differs from its congeners by possession of an S-shaped ovary, a Y-shaped oviduct leading to a separate receptaculum seminis, and the shape and size of the male copulatory organ.



Short-Term Toxicity of Five Oil s to Four Freshwater Species.  

National Technical Information Service (NTIS)

Short-term lethality tests were conducted with five (waste oil, No. 1 fuel oil, No. 2 fuel oil, mixed blend sweet crude oil, Lloydminister crude oil) oils and four freshwater species. The oils were tested as floating layers, emulsions, and as the water-so...

S. F. Hedtke F. A. Puglisi



Macrophyte Species Drive the Variation of Bacterioplankton Community Composition in a Shallow Freshwater Lake  

PubMed Central

Macrophytes play an important role in structuring aquatic ecosystems. In this study, we explored whether macrophyte species are involved in determining the bacterioplankton community composition (BCC) in shallow freshwater lakes. The BCC in field areas dominated by different macrophyte species in Taihu Lake, a large, shallow freshwater lake, was investigated over a 1-year period. Subsequently, microcosm experiments were conducted to determine if single species of different types of macrophytes in an isolated environment would alter the BCC. Denaturing gradient gel electrophoresis (DGGE), followed by cloning and sequence analysis of selected samples, was employed to analyze the BCC. The DGGE results of the field investigations indicated that the BCC changed significantly from season to season and that the presence of different macrophyte species resulted in lower BCC similarities in the summer and fall. LIBSHUFF analysis of selected clone libraries from the summer demonstrated different BCCs in the water column surrounding different macrophytes. Relative to the field observations, the microcosm studies indicated that the BCC differed more pronouncedly when associated with different species of macrophytes, which was also supported by LIBSHUFF analysis of the selected clone libraries. Overall, this study suggested that macrophyte species might be an important factor in determining the composition of bacterial communities in this shallow freshwater lake and that the species-specific influence of macrophytes on BCC is variable with the season and distance.

Zeng, Jin; Bian, Yuanqi; Xing, Peng



Impact of resource availability on species composition and diversity in freshwater nematodes.  


This study investigates the long-term effects of resource availability in a freshwater nematode community. We carried out a mesocosm experiment where natural nematode communities were exposed to nutrient addition/depletion over 2 years. Compared to the nutrient-addition treatment, species richness and diversity were strongly reduced upon nutrient depletion. The functional group of bacterial feeders particularly suffered severely from nutrient depletion. The decrease in diversity of bacterial feeders was linked to reduced species richness and diversity of large omnivorous species, as predicted by trophic-dynamic models. Tilman's (1976) statement, that under low nutrient levels the best competitor dominates the system, was applicable in our system. Upon nutrient depletion, resource depletion led to a monoculture of 1 small bacterial feeder, but even after 2 years of resource depletion, up to 16 species still coexisted. Our results provide strong evidence that freshwater nematode systems can be regulated by nutrient competition. PMID:15365809

Michiels, Iris C; Traunspurger, Walter



Recent thermal history influences thermal tolerance in freshwater mussel species (Bivalvia: Unionoida)  

USGS Publications Warehouse

Understanding species’ temperature tolerances in the context of concurrent environmental stressors is critical because thermal regimes of freshwater ecosystems are changing. We evaluated the critical thermal maximum (CTM) of 3 freshwater mussel species (Alasmidonta varicosa, Elliptio complanata, and Strophitus undulatus) acclimated to 2 temperatures (15 and 25°C) and exposed to 2 aeration treatments (aerated vs unaerated) during CTM testing. Responses varied by species, but mussels acclimated to 25°C generally had a higher CTM than mussels acclimated to 15°C. For E. complanata, the effects of acclimation temperature and aeration were interactive, such that CTM was highest at 15°C but only under aerated conditions. Our results indicate that recent thermal history affects thermal tolerance, combinations of environmental stressors may influence thermal tolerance, and such responses vary among species.

Galbraith, Heather S.



Interspecific differences in chemosensory responses of freshwater turtles: consequences for competition between native and invasive species  

Microsoft Academic Search

The red-eared slider (Trachemys scripta elegans) is an introduced invasive species in many Mediterranean countries that is displacing the populations of native endangered\\u000a Spanish terrapins (Mauremys leprosa). However, it is relatively unknown how potential competitive interactions could be taking place. In many freshwater turtles,\\u000a semiochemicals from different glands might facilitate species and sex recognition. We hypothesized that chemosensory detection\\u000a of

Nuria Polo-Cavia; Pilar López; José Martín



A literature analysis of freshwater invasive species research: are empiricists, theoreticians, and economists working together?  

Microsoft Academic Search

Cross-disciplinary empirical and economic research, bridged by theoretical modelling, are critical research approaches in\\u000a the development of effective policy and management actions to prevent and control the negative consequences of species invasions.\\u000a We conducted a literature analysis of freshwater invasive species research to determine the prevalence of integrated research\\u000a approaches, gaps in the current knowledge base, and to suggest future

Caroline J. Bampfylde; Jody A. Peters; Angela M. Bobeldyk



Using remote underwater video to estimate freshwater fish species richness.  


Species richness records from replicated deployments of baited remote underwater video stations (BRUVS) and unbaited remote underwater video stations (UBRUVS) in shallow (<1 m) and deep (>1 m) water were compared with those obtained from using fyke nets, gillnets and beach seines. Maximum species richness (14 species) was achieved through a combination of conventional netting and camera-based techniques. Chanos chanos was the only species not recorded on camera, whereas Lutjanus argentimaculatus, Selenotoca multifasciata and Gerres filamentosus were recorded on camera in all three waterholes but were not detected by netting. BRUVSs and UBRUVSs provided versatile techniques that were effective at a range of depths and microhabitats. It is concluded that cameras warrant application in aquatic areas of high conservation value with high visibility. Non-extractive video methods are particularly desirable where threatened species are a focus of monitoring or might be encountered as by-catch in net meshes. PMID:23639156

Ebner, B C; Morgan, D L



Misidentification of freshwater mussel species (Bivalvia:Unionidae): Contributing factors, management implications, and potential solutions  

USGS Publications Warehouse

Surveys of freshwater mussel populations are used frequently to inform conservation decisions by providing information about the status and distribution of species. It is generally accepted that not all mussels or species are collected during surveys, and incomplete detection of individuals and species can bias data and can affect inferences. However, considerably less attention has been given to the potential effects of species misidentification. To evaluate the prevalence of and potential reasons for species misidentification, we conducted a laboratory-based identification exercise and quantified the relationships between mussel species characteristics, observer experience, and misidentification rate. We estimated that misidentification was fairly common, with rates averaging 27% across all species and ranging from 0 to 56%, and was related to mussel shell characteristics and observer experience. Most notably, species with shell texturing were 6.09?? less likely than smooth-shelled species to be misidentified. Misidentification rates declined with observer experience, but for many species the risk of misidentification averaged >10% even for observers with moderate levels of experience (5-6 y). In addition, misidentification rates among observers showed substantial variability after controlling for experience. Our results suggest that species misidentification may be common in field surveys of freshwater mussels and could potentially bias estimates of population status and trends. Misidentification rates possibly could be reduced through use of regional workshops, testing and certification programs, and the availability of archived specimens and tissue samples in museum collections. ?? 2011 The North American Benthological Society.

Shea, C. P.; Peterson, J. T.; Wisniewski, J. M.; Johnson, N. A.



Patterns in species richness and endemism of European freshwater fish  

Microsoft Academic Search

Aim To analyse the patterns in species richness and endemism of the native European riverine fish fauna, in the light of the Messinian salinity crisis and the Last Glacial Maximum (LGM). Location European continent.

Yorick Reyjol; Bernard Hugueny; Didier Pont; Pier Giorgio Bianco; Ulrika Beier; Nuño Caiola; Frederic Casals; Ian Cowx; Alcibiades Economou; Teresa Ferreira; Gertrud Haidvogl; Richard Noble; Adolfo de Sostoa; Thibault Vigneron; Tomas Virbickas



Context-Dependent Species Effects in Freshwater Mussel Communities  

NASA Astrophysics Data System (ADS)

Riverine unionids typically occur as multi-species assemblages and are considered a `filter-feeding' guild. Through a series of field-enclosure and laboratory stream-mesocosm experiments we are addressing three fundamental questions concerning this guild: (1) What is the overall importance of the mussel guild to stream ecosystem function? (2) Do species perform different ecological roles or are they functionally redundant? and (3) Do species roles vary with environmental context? Results to date demonstrate strong effects of a potentially keystone species, Actinonaias ligamentina, but comparatively weak diversity effects. In summer field experiments, A. ligamentina increased periphyton biomass, and A. ligamentina biomass was correlated with biomass changes in other mussel species. These patterns were not observed in fall field experiments when water temperatures were lower and average discharge higher. Most of the samples from the mesocosm experiments are still being processed, but data we have analyzed also indicate strong effects of A. ligamentina on both whole community respiration rates and biodeposition of organic matter. Our results indicate that some mussel species are performing differently in streams and are thus not redundant, but that performance and potential redundancy are context dependent.

Vaughn, C. C.; Spooner, D. E.; Galbraith, H. S.



Novel Cyanobacterial Biosensor for Detection of Herbicides  

PubMed Central

The aim of this work was to generate a cyanobacterial biosensor that could be used to detect herbicides and other environmental pollutants. A representative freshwater cyanobacterium, Synechocystis sp. strain PCC6803, was chromosomally marked with the luciferase gene luc (from the firefly Photinus pyralis) to create a novel bioluminescent cyanobacterial strain. Successful expression of the luc gene during growth of Synechocystis sp. strain PCC6803 cultures was characterized by measuring optical density and bioluminescence. Bioluminescence was optimized with regard to uptake of the luciferase substrate, luciferin, and the physiology of the cyanobacterium. Bioassays demonstrated that a novel luminescent cyanobacterial biosensor has been developed which responded to a range of compounds including different herbicide types and other toxins. This biosensor is expected to provide new opportunities for the rapid screening of environmental samples or for the investigation of potential environmental damage.

Shao, C. Y.; Howe, C. J.; Porter, A. J. R.; Glover, L. A.



Toxins produced in cyanobacterial water blooms - toxicity and risks  

PubMed Central

Cyanobacterial blooms in freshwaters represent a major ecological and human health problem worldwide. This paper briefly summarizes information on major cyanobacterial toxins (hepatotoxins, neurotoxins etc.) with special attention to microcystins-cyclic heptapeptides with high acute and chronic toxicities. Besides discussion of human health risks, microcystin ecotoxicology and consequent ecological risks are also highlighted. Although significant research attention has been paid to microcystins, cyanobacteria produce a wide range of currently unknown toxins, which will require research attention. Further research should also address possible additive, synergistic or antagonistic effects among different classes of cyanobacterial metabolites, as well as interactions with other toxic stressors such as metals or persistent organic pollutants.

Blaha, Ludek; Babica, Pavel; Marsalek, Blahoslav



Seed germination of three species of Vallisneria (Hydrocharitaceae), and the effects of freshwater microalgae  

Microsoft Academic Search

Two experiments were conducted to investigate seed germination under natural temperature and light regimes and to evaluate the influence of freshwater microalgae on seed germination of threeVallisneria species. Seeds exposed to natural seasonal temperature and light changes for 24?months germinated only in spring, perhaps indicating an annual dormancy\\/non-dormancy cycle. The ecological background of the natural habitat seems to play predominant

Li Zhongqiang; Dan Yu; Tu Manghui



Interaction between zinc and freshwater and marine diatom species: Surface complexation and Zn isotope fractionation  

Microsoft Academic Search

This work is devoted to characterization of zinc interaction in aqueous solution with two marine planktonic (Thalassiosira weissflogii=TW, Skeletonema costatum=SC) and two freshwater periphytic species (Achnanthidium minutissimum=AMIN, Navicula minima=NMIN) by combining adsorption and electrophoretic measurements with surface complexation modeling and by assessing Zn isotopes fractionation during both long term uptake and short term adsorption on diatom cells and their frustules.

A. Gélabert; O. S. Pokrovsky; J. Viers; J. Schott; A. Boudou; A. Feurtet-Mazel



Toxic effects of zinc on four species of freshwater fish  

NASA Astrophysics Data System (ADS)

The toxic effects of Zn2+ on Silver Carp ( Hypophthalmichthyps molitrix C. et V.), Big Head Carp ( Aristrichthys nobilis Richardson), Grass Carp ( Ctenopharyngodon ilellus C. et V.), and Blunt Snout Bream ( Megalobrama aimbly-cephala Yih) are studied. The test results are: (1) There are linear correlations between 24h LC50 and 48h LC50 of Zn2+ for Silver Carp fingerling and temperature. 24h LC50, 48h LC50 and 96h LC50 of Zn2+ for fry of the four species are also determined; (2) There are logarithmic correlations between the growth rates of the fry and the concentrations of Zn2+ and between expansion of fish egg membranes after absorbing water and concentrations of Zn2+; (3) The tolerance of fry of the four species to Zn2+ is in the following order: Grass Carp>Silver Carp>Blunt Snout Bream>Big Head Carp; (4) The safe concentrations of Zn2+ are: Big Head Carp: 0.008 mg/L, Grass Carp: 0.046 mg/L, Blunt Snout Bream: 0.010 mg/L, Silver Carp: 0.012 mg/L, Silver Carp fingerling: 0.09 mg/L.

Zang, Weiling; Ye, Lin; Xu, Xuancheng; Gong, Shuchun



Simultaneous Multiple Species Testing: Acute Toxicity of 13 Chemicals to 12 Diverse Freshwater Amphibian, Fish, and Invertebrate Families.  

National Technical Information Service (NTIS)

The test series developed methods for testing a compliment of aquatic organisms in a single test that satisfies the freshwater acute toxicity requirements for setting water quality criteria. Species tested included fathead minnows Pimephales promelas, rai...

G. W. Holcombe G. L. Phipps A. H. Sulaiman A. D. Hoffman



Diversification and Species Boundaries of Rhinebothrium (Cestoda; Rhinebothriidea) in South American Freshwater Stingrays (Batoidea; Potamotrygonidae)  

PubMed Central

Background Neotropical freshwater stingrays (Batoidea: Potamotrygonidae) host a diverse parasite fauna, including cestodes. Both cestodes and their stingray hosts are marine-derived, but the taxonomy of this host/parasite system is poorly understood. Methodology Morphological and molecular (Cytochrome oxidase I) data were used to investigate diversity in freshwater lineages of the cestode genus Rhinebothrium Linton, 1890. Results were based on a phylogenetic hypothesis for 74 COI sequences and morphological analysis of over 400 specimens. Cestodes studied were obtained from 888 individual potamotrygonids, representing 14 recognized and 18 potentially undescribed species from most river systems of South America. Results Morphological species boundaries were based mainly on microthrix characters observed with scanning electron microscopy, and were supported by COI data. Four species were recognized, including two redescribed (Rhinebothrium copianullum and R. paratrygoni), and two newly described (R. brooksi n. sp. and R. fulbrighti n. sp.). Rhinebothrium paranaensis Menoret & Ivanov, 2009 is considered a junior synonym of R. paratrygoni because the morphological features of the two species overlap substantially. The diagnosis of Rhinebothrium Linton, 1890 is emended to accommodate the presence of marginal longitudinal septa observed in R. copianullum and R. brooksi n. sp. Patterns of host specificity and distribution ranged from use of few host species in few river basins, to use of as many as eight host species in multiple river basins. Significance The level of intra-specific morphological variation observed in features such as total length and number of proglottids is unparalleled among other elasmobranch cestodes. This is attributed to the large representation of host and biogeographical samples. It is unclear whether the intra-specific morphological variation observed is unique to this freshwater system. Nonetheless, caution is urged when using morphological discontinuities to delimit elasmobranch cestode species because the amount of variation encountered is highly dependent on sample size and/or biogeographical representation.

Reyda, Florian B.; Marques, Fernando P. L.



Three new species of Rhinebothrium (Cestoda: Tetraphyllidea) from the freshwater whipray, Himantura chaophraya, in Malaysian Borneo.  


Three new Rhinebothrium Linton, 1890 species, R. kinabatanganensis n. sp., R. megacanthophallus n. sp., and R. abaiensis n. sp., collected from the spiral intestines of 6 freshwater whiprays (Himantura chaophraya, Dasyatidae) in the Kinabatangan River, Malaysian Borneo, are described. This is the first record of cestodes from the Kinabatangan River and from H. chaophraya. The new Rhinebothrium species are differentiated from the 34 valid Rhinebothrium species in addition to 2 species, Echeneibothrium hui Tseng, 1933 and E. oligotesticularis Subramaniam, 1940 that are herein transferred to Rhinebothrium. Each of the new species was examined with light and scanning electron microscopy. Two of the new species possess cilia on their bothridia, which have not previously been reported for members of this genus. PMID:16729696

Healy, Claire J



Ligand-binding assays for cyanobacterial neurotoxins targeting cholinergic receptors  

Microsoft Academic Search

Toxic cyanobacterial blooms are a threat to public health because of the capacity of some cyanobacterial species to produce\\u000a potent hepatotoxins and neurotoxins. Cyanobacterial neurotoxins are involved in the rapid death of wild and domestic animals\\u000a by targeting voltage gated sodium channels and cholinergic synapses, including the neuromuscular junction. Anatoxin-a and\\u000a its methylene homologue homoanatoxin-a are potent agonists of nicotinic

Rómulo Aráoz; Natalia Vilariño; Luis M. Botana; Jordi Molgó



Biodiversity of Australian freshwater planarians (Platyhelminthes: Tricladida: Paludicola): New species and localities, and a review of paludicolan distribution in Australia  

Microsoft Academic Search

On the basis of one extensive collection, the study provides new information on the diversity, taxonomy, anatomy and geographic distribution of 21 species of Australian freshwater planarians, including 7 species that are described as new. The material includes old type specimens of three species that have remained enigmatic since their collection and description almost 100 years ago, viz. Planaria rava

Lauryne J. Grant; Ronald Sluys; David Blair



Quantitative determination of rarity of freshwater fishes and implications for imperiled-species designations.  


Conserving rare species and protecting biodiversity and ecosystem functioning depends on sound information on the nature of rarity. Rarity is multidimensional and has a variety of definitions, which presents the need for a quantitative classification scheme with which to categorize species as rare or common. We constructed such a classification for North American freshwater fishes to better describe rarity in fishes and provide researchers and managers with a tool to streamline conservation efforts. We used data on range extents, habitat specificities, and local population sizes of North American freshwater fishes and a variety of quantitative methods and statistical decision criteria, including quantile regression and a cost-function algorithm to determine thresholds for categorizing a species as rare or common. Species fell into eight groups that conform to an established framework for rarity. Fishes listed by the American Fisheries Society (AFS) as endangered, threatened, or vulnerable were most often rare because their local population sizes were low, ranges were small, and they had specific habitat needs, in that order, whereas unlisted species were most often considered common on the basis of these three factors. Species with large ranges generally had few specific habitat needs, whereas those with small ranges tended to have narrow habitat specificities. We identified 30 species not designated as imperiled by AFS that were rare along all dimensions of rarity and may warrant further study or protection, and we found three designated species that were common along all dimensions and may require a review of their imperilment status. Our approach could be applied to other taxa to aid conservation decisions and serve as a useful tool for future revisions of listings of fish species. PMID:20337684

Pritt, Jeremy J; Frimpong, Emmanuel A



Toxicity of hydroquinone to different freshwater phototrophs is influenced by time of exposure and pH.  


The interaction of natural organic matter with phytoplankton communities in freshwater ecosystems is an intensively studied subject matter. Previous studies showed that apparently plant-derived phenols were able to inhibit algal and cyanobacterial growth. Furthermore, it was also assumed that humic substances (HS), which comprise the major part of dissolved organic carbon in freshwater ecosystems, directly interact with freshwater phototrophs. For example, quinoid building blocks of HS were thought to be algicidal. To identify key environmental variable for the toxic action of potential quinone algicides, we tested the toxicity of hydroquinone (HQ) to different eukaryotic and prokaryotic freshwater phototrophs in terms of growth performance and investigated also the effect of HQ oxidation at different pH values on its algicidal potential. It was shown that cyanobacterial species were much more susceptible to hydroquinone than coccal green algal species were, with Microcystis aeruginosa being the most sensitive species by far. In addition, it was obvious that the aging of hydroquinone-stock solution at pH 11 led to polymerization and, by this process, to a total loss of toxicity; whereas the algicidal potential sustained if the polyphenol was kept at pH 7. Since most lakes with heavy blooms of phototrophs possess pH values clearly above 7.0, it is questionable, if polyphenols in general and quinones in particular are the effective chemicals and if litter and straw leachates are applied as means to combat algal and cyanobacterial blooms. PMID:22956111

Bährs, Hanno; Putschew, Anke; Steinberg, Christian E W



Species-specific and transgenerational responses to increasing salinity in sympatric freshwater gastropods.  


Freshwater salinization is a global concern partly attributable to anthropogenic salt contamination. The authors examined the effects of increased salinity (as NaCl, 250-4,000 µS/cm, specific conductance) on two sympatric freshwater gastropods (Helisoma trivolvis and Physa pomillia). Life stage sensitivities were determined by exposing naive eggs or naive juveniles (through adulthood and reproduction). Additionally, progeny eggs from the juvenile-adult exposures were maintained at their respective parental salinities to examine transgenerational effects. Naive H. trivolvis eggs experienced delayed development at specific conductance > 250 µS/cm; reduced survivorship and reproduction were also seen in juvenile H. trivolvis at 4,000 µS/cm. Survival and growth of P. pomilia were not affected by increased salinity following egg or juvenile exposures. Interestingly, the progeny of H. trivolvis exposed to higher salinity may have gained tolerance to increased salinity whereas P. pomilia progeny may have experienced negative transgenerational effects. The present study demonstrates that freshwater snail species vary in their tolerance to salinization and also highlights the importance of multigenerational studies, as stressor impacts may not be readily apparent from shorter term exposures. PMID:22865709

Suski, Jamie G; Salice, Christopher J; Patiño, Reynaldo



Two new species of bucephalids (Digenea: Bucephalidae) parasitic in freshwater fishes of Argentina.  


Two new species of bucephalids (Digenea: Bucephalidae) were found parasitizing freshwater fishes of Argentina. Prosorhynchoides cambapuntaensis sp. n. from Salminus maxillosus (Characidae) is characterised by the tegument covered with two kinds of spines, scale-like spines anteriorly and fine spines posteriorly; uterine loops reaching the vitelline arch in the pre-oral region; and the Laurer's canal short, opening dorsally immediately posterior to the ovary. Rhipidocotyle santanaensis sp. n. from Acestrorhynchus pantaneiro (Acestrorhynchidae) is characterised by the rhynchus with two lateral projections; the testes arranged in tandem or slightly diagonal; and the vitelline follicles forming an arch in the pre-oral region. PMID:15468530

Lunaschi, Lía I



Is the freshwater gammarid, Dikerogammarus villosus, a suitable sentinel species for the implementation of histochemical biomarkers?  


In order to enlarge the range of potential sentinel species for the implementation of a multiple biomarker approach, spatial and monthly morphological variations of four cellular compartments and contents were assessed during two years in the hepatopancreatic caeca of the freshwater gammarid, Dikerogammarus villosus (Crustacea, Amphipoda), using histochemistry coupled to image analysis. Among the three study sites, the second one, located in a reservoir receiving the overheated and copper-contaminated waters of a nuclear power plant, was the most anthropised. During this passive biomonitoring survey, unsaturated neutral lipids were more abundant, the surface densities of the lysosomal and peroxisomal systems were, respectively less and more important, and lipofuscin granules tended to accumulate in the amphipods from the second site compared to both others. Nonetheless, in this context, the present cellular biomarker suite, analysed through an integrative approach, was not powerful enough to highlight spatial heterogeneity significantly. This may partly result from particularities in the patterns of metal accumulation and copper physiological requirements of amphipods (haemocyanin synthesis). Nevertheless, we think that the use of this Ponto-Caspian non-indigenous species in biomonitoring surveys deserves further investigation, owing to its current position in freshwater and brackish European ecosystems, considering both biomass and functioning. Cellular responses could be studied in parallel with endpoints at other levels of the biological organization to compose a more powerful biomarker suite. Furthermore, comparing biological responses to environmental stress in this invasive species and less competitive autochthonous gammarids could be of great interest. PMID:18499217

Guerlet, Edwige; Ledy, Karine; Giambérini, Laure



Screening of freshwater fish species for their susceptibility to a betanodavirus.  


Betanodaviruses, the causative agents of viral nervous necrosis in marine fish, have bipartite positive-sense RNA genomes. Because the genomes are the smallest and simplest among viruses, betanodaviruses have been well studied using a reversed genetics system as model viruses. However, studies of virus-host interactions have progressed slowly because permissive hosts for betanodaviruses (basically larvae and juveniles of marine fish) are only available for limited periods of the year and are not suitable for the construction of a genetic engineering system. To obtain a model fish species that are not subject to these problems, 21 freshwater fish species were injected intramuscularly with a betanodavirus (redspotted grouper nervous necrosis virus) and tested for their susceptibility to the virus. Based on their responses, the tested fish were classified into 3 groups: 4 susceptible fish, 10 less susceptible fish, and 7 resistant fish. The susceptible fish, celebes rainbowfish Telmatherina ladigesi, threadfin rainbowfish Iriatherina werneri, dwarf rainbowfish Melanotaenia praecox, and medaka Oryzias latipes, exhibited erratic swimming and eventually died within 10 d post-inoculation. The virus was specifically localized in the brains, spinal cords, and retinas of the infected fish, similar to the pattern of infection in naturally infected marine fish. We believe that these susceptible freshwater fish species could act as good host models for betanodavirus-fish interaction studies. PMID:17972753

Furusawa, Ryo; Okinaka, Yasushi; Uematsu, Kazumasa; Nakai, Toshihiro



A new allocreadiid (Trematoda) species from freshwater fish Heterandria bimaculata (Teleostei: Poeciliidae) in Southeastern Mexico.  


Paracreptotrema heterandriae n. sp. (Trematoda: Allocreadiidae) is described from the intestine of the freshwater fish Heterandria bimaculata (Teleostei: Poeciliidae) from the upper basin of Río La Antigua, in Veracruz, Mexico. The new species is distinguished from the 3 others in the Paracreptotrema Choudhury, Pérez-Ponce de León, Brooks, and Daverdin, 2006 , mainly by having a feeble membranous cirrus sac containing an uncoiled seminal vesicle, instead of a well-developed muscular cirrus sac that encloses coiled seminal vesicle, pars prostatica, and ejaculatory duct as in the previously 3 nominal species. Moreover, eggs of the new species are larger than all others ([measurements in micrometers] eggs of P. heterandriae n. sp. 72.5 [70-75] × 40 [35-41]; P. blancoi 55.4 [52.5-62.5] × 38.5 [32.5-42.5]; P. mendezi 46 × 37; P. profundulusi 57 [52-60] × 27.8 [25-30]). PMID:22059430

Salgado-Maldonado, Guillermo; Caspeta-Mandujano, Juan Manuel; Vázquez, Gabriela



A model of phycotoxin release by cyanobacterial cells  

Microsoft Academic Search

The paper presents a semi-empirical mathematical model for phycotoxin release into water during the development of the freshwater cyanobacterial population. The data obtained from field observation and laboratory experiments demonstrate correlation between the development of cell population and phycotoxin concentration in water (National Rivers Authority, 1990. Toxic Blue-Green Algae. A Report by the National Rivers Authority. Water Quality Series, September

A. P Belov



Responses of seven species of native freshwater fish and a shrimp to low levels of dissolved oxygen  

Microsoft Academic Search

The tolerances of seven New Zealand freshwater fish species and one species of shrimp to low levels of dissolved oxygen were determined in the laboratory by holding fish at dissolved oxygen levels of 1, 3, or 5 mg litre for 48 h at 15°C. Juvenile rainbow trout (Oncorhynchus mykiss) were also tested for comparison. All of the banded kokopu whitebait

Tracie L. Dean; Jody Richardson



Phylogeography of Cambarus tenebrosus: a Facultative Cave-Dwelling Freshwater Crayfish Species.  

NASA Astrophysics Data System (ADS)

Cambarus tenebrosus is a unique freshwater crayfish species, inhabiting both subterranean and surface habitats in southeastern United States. This facultative cave-dweller is found in all aquatic karst areas within its range, including deep pits, massive underground rivers, springs, and surface streams, which makes this species ideal for a phylogeographic study. The objectives of our research are to: 1.) determine if C. tenebrosus is a single lineage or represents multiple cryptic species using phylogenetic methods, 2.) evaluate the evolutionary history and current gene flow patterns of C. tenebrosus using Nested Clade Analysis, and 3.) assess genetic diversity and conservation status of the species. We have gathered molecular genetic data from over 300 individuals from cave and surface environments across the entire range, with focus on the Cumberland Plateau from Kentucky to Alabama. Preliminary findings suggest that there are several clades of C. tenebrosus, but these clades geographically overlap in many areas. There is also no association between genetics and habitat (surface vs. subsurface), suggesting that there is gene flow between the two environment types. The origin of the species appears to be around Western Kentucky and Indiana, which then expanded southward down the Cumberland Plateau.

Finlay, J.; Buhay, J. E.; Crandall, K. A.



Low oxygen tolerance of different life stages of temperate freshwater fish species.  


Data on low dissolved oxygen (DO?) tolerance of freshwater fish species of north-western Europe were used to create species sensitivity distributions (SSD). Lowest observed effect concentrations (LOEC) and 100% lethal concentrations (LC???) data were collected from the scientific literature. Comparisons were made among life stages as well as between native and exotic species. In addition, lethal DO? concentrations were compared to oxygen concentrations corresponding to maximum tolerable water temperatures of the same species. Fish eggs and embryos were the least tolerant. Juveniles had a significantly lower mean LOEC than adults, but there was no difference in mean LC??? between the two groups. The difference in lethal oxygen concentrations between adults and juveniles was largest for three salmonids, although it remains uncertain if this was a result of smoltification. There were no significant differences between native and exotic species; however, data on exotics are limited. DO? concentrations converted from maximum tolerable water temperatures were 3·9 times higher than the measured lethal DO? concentrations, which may reflect changes in respiration rates (Q??) and may also relate to the simplicity of the model used. PMID:23808700

Elshout, P M F; Dionisio Pires, L M; Leuven, R S E W; Wendelaar Bonga, S E; Hendriks, A J



Cyanobacterial NADPH dehydrogenase complexes  

Microsoft Academic Search

Cyanobacteria possess functionally distinct multiple NADPH dehydrogenase (NDH-1) complexes that are essential to CO2 uptake, photosystem-1 cyclic electron transport and respiration. The unique nature of cyanobacterial NDH-1 complexes is the\\u000a presence of subunits involved in CO2 uptake. Other than CO2 uptake, chloroplastic NDH-1 complex has a similar role as cyanobacterial NDH-1 complexes in photosystem-1 cyclic electron\\u000a transport and respiration (chlororespiration).

Teruo Ogawa; Hualing Mi



Cyanobacterial signature genes  

Microsoft Academic Search

A comparison of 8 cyanobacterial genomes reveals that there are 181 shared genes that do not have obvious orthologs in other\\u000a bacteria. These signature genes define aspects of the genotype that are uniquely cyanobacterial. Approximately 25% of these\\u000a genes have been associated with some function. These signature genes may or may not be involved in photosynthesis but likely\\u000a they will

Kirt A. Martin; Janet L. Siefert; Sailaja Yerrapragada; Yue Lu; Thomas Z. McNeill; Pedro A. Moreno; George M. Weinstock; William R. Widger; George E. Fox



Freshwater Influence Over the South Brazilian Continental Shelf: Indications From Foraminiferal Species Dominance  

NASA Astrophysics Data System (ADS)

The 250-km-long Patos Lagoon covers an area of 10,360 km2 along the coastal plain of Rio Grande do Sul in southern Brazil. To the north, the 40-km-long Laguna estuarine system along the Santa Catarina coastline is essentially a series of choked coastal lagoons, with elliptical cells connected to the ocean via a single long and narrow channel. We examined the distribution of benthic foraminifera in samples collected from two continental-shelf transects, labeled the Albardäo transect (32° 58'S) and Santa Marta Cape transect (28° 34'S), in order to track the influence of the Patos Lagoon and the Laguna estuarine system in the dilution of shelf waters. In the Albardäo transect, we notice the dominance of Bulimininella elegantissima and Bolivina striatula live individuals in the shallower stations (15-42 m). These low-oxygen tolerant species are also found in muddy sediments of the Patos lagoon and near the mouth of the Plata River; their presence in shelf sediments indicates continental runoff in the region. Very large individuals of the agglutinated species Arenoparella mexicana and Gaudryina exilis (present in brackish waters Patos Lagoon) are found in water depths 19-54 m, also suggesting a strong and deep freshwater influence. At the 90-m isobath, (1) the species diversity shows a rise, and (2) larger agglutinated species and Buccela peruviana, a temperate/cold-water hyaline species, are occasionally present. B. peruviana is characteristic of assemblages influenced by the Malvinas Current, and indicates the presence of Sub-Antarctic Shelf Water (SASW). In contrast, the dominant species at 53 m on the Santa Marta Cape transect are Bulimina marginata and Pseudononion atlanticum. These species, together with small individuals of Arenoparella mexicana and Gaudryina exilis, show that the Santa Marta Cape area is under a major influence of Subtropical Shelf Waters (STSW), and that fresh-water influence is minor. The assemblage from the deepest stations on this transect (75, 109m) is dominated by Uvigerina peregrina and Cassidulina subglobosa, which indicates the presence of the cold, nutrient-rich South Atlantic Central Water (SACW).

Eichler, P. P.; Sen Gupta, B. K.; Eichler, B. B.; Campos, E. J.



Genetic diversity of freshwater crabs (Brachyura: Sesarmidae) from central Jamaica with description of a new species  

Microsoft Academic Search

Jamaica is the only island of the Greater Antilles where freshwater streams are not populated by representatives of the old lineage of freshwater crabs, the Pseudothelphusidae. Instead, a very diverse fauna of endemic sesarmid crabs inhabits freshwater and terrestrial habitats throughout the island, thereby showing complete independence from the sea. They have been reported thriving in bromeliad leaf axils, rock

Christoph D. Schubart; Peter Koller



Neurotoxic cyanobacterial toxins.  


Worldwide development of cyanobacterial blooms has significantly increased in marine and continental waters in the last century due to water eutrophication. This phenomenon is favoured by the ability of planktonic cyanobacteria to synthesize gas vesicles that allow them to float in the water column. Besides, benthic cyanobacteria that proliferate at the bottom of lakes, rivers and costal waters form dense mats near the shore. Cyanobacterial massive proliferation is of public concern regarding the capacity of certain cyanobacterial strains to produce hepatotoxic and neurotoxic compounds that can affect public health, human activities and wild and stock animals. The cholinergic synapses and voltage-gated sodium channels constitute the targets of choice of cyanobacterial neurotoxins. Anatoxin-a and homoanatoxin-a are agonists of nicotinic acetylcholine receptors. Anatoxin-a(s) is an irreversible inhibitor of acetylcholinesterase. Saxitoxin, kalkitoxin and jamaicamide are blockers of voltage-gated sodium channels, whereas antillatoxin is an activator of such channels. Moreover the neurotoxic amino acid l-beta-N-methylamino-l-alanine was shown to be produced by diverse cyanobacterial taxa. Although controversial, increasing in vivo and in vitro evidence suggest a link between the ingestion of l-beta-N-methylamino-l-alanine and the development of amyotrophic lateral sclerosis/Parkinsonism-dementia complex, a neurodegenerative disease. This paper reviews the occurrence of cyanobacterial neurotoxins, their chemical properties, mode of action and biosynthetic pathways. PMID:19660486

Aráoz, Rómulo; Molgó, Jordi; Tandeau de Marsac, Nicole



Distinct migratory and non-migratory ecotypes of an endemic New Zealand eleotrid (Gobiomorphus cotidianus) – implications for incipient speciation in island freshwater fish species  

Microsoft Academic Search

BACKGROUND: Many postglacial lakes contain fish species with distinct ecomorphs. Similar evolutionary scenarios might be acting on evolutionarily young fish communities in lakes of remote islands. One process that drives diversification in island freshwater fish species is the colonization of depauperate freshwater environments by diadromous (migratory) taxa, which secondarily lose their migratory behaviour. The loss of migration limits dispersal and

Christian Michel; Brendan J Hicks; Kai N Stölting; Andrew C Clarke; Mark I Stevens; Ray Tana; Axel Meyer; Michael R van den Heuvel



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

PubMed Central

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.

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



Warm season chloride concentrations in stream habitats of freshwater mussel species at risk.  


Warm season (May-October) chloride concentrations were assessed in stream habitats of freshwater mussel species at risk in southern Ontario, Canada. Significant increases in concentrations were observed at 96% of 24 long-term (1975-2009) monitoring sites. Concentrations were described as a function of road density indicating an anthropogenic source of chloride. Linear regression showed that 36% of the variation of concentrations was explained by road salt use by the provincial transportation ministry. Results suggest that long-term road salt use and retention is contributing to a gradual increase in baseline chloride concentrations in at risk mussel habitats. Exposure of sensitive mussel larvae (glochidia) to increasing chloride concentrations may affect recruitment to at risk mussel populations. PMID:22940273

Todd, Aaron K; Kaltenecker, M Georgina



Screening of terrestrial and freshwater halotolerant cyanobacteria for antifungal activities  

Microsoft Academic Search

Cyanobacterial cultures tolerating 200 mmol l?1 sodium chloride isolated from terrestrial and freshwater habitats of North Maharashtra region of India were evaluated for\\u000a antifungal activity. Aqueous, methanol, n-propanol, and petroleum ether extracts of 40 cyanobacterial isolates belonging to nine genera were examined for inhibitory\\u000a activity against five fungal pathogens. Eighteen isolates belonging to genus Oscillatoria dominated the population of halotolerant cyanobacterial cultures.

Sunil T. Pawar; Pravin R. Puranik



Acute toxicity of six freshwater mussel species (Glochidia) to six chemicals: Implications for daphnids and Utterbackia imbecillis as surrogates for protection of freshwater mussels (Unionidae)  

USGS Publications Warehouse

Acute (24-h) toxicity tests were used in this study to compare lethality responses in early life stages (glochidia) of six freshwater mussel species, Leptodea fragilis, U. imbecillis, Lampsilis cardium, Lampsilis siliquoidea, Megalonaias nervosa, and Ligumia subrostrata, and two standard test organisms, Ceriodaphnia dubia and Daphnia magna. Concentrations of carbaryl, copper, 4-nonylphenol, pentachlorophenol, permethrin, and 2,4-D were used in acute exposures to represent different chemical classes and modes of action. The relative sensitivities of species were evaluated by ranking their LC 50 values for each chemical. We used these ranks to determine the extent to which U. imbecillis (one of the most commonly used unionids in toxicity tests) was representative of the tolerances of other mussels. We also calculated geometric mean LC50s for the families Unionidae and Daphnidae. Rankings of these data were used to assess the extent to which Daphnidae can be used as surrogates for freshwater mussels relative to chemical sensitivity. While no single chemical elicited consistently high or low toxicity estimates, carbaryl and 2,4-D were generally the least toxic to all species tested. No species was always the most sensitive, and Daphnidae were generally protective of Unionidae. Utterbackia imbecillis, while often proposed as a standard unionid mussel test species, did not always qualify as a sufficient surrogate (i.e., a substitute organism that often elicits similar sensitivity responses to the same contaminant exposure) for other species of mussels, since it was usually one of the more tolerant species in our rankings. U. imbecillis should be used as a surrogate species only with this caution on its relative insensitivity. ?? 2005 Springer Science+Business Media, Inc.

Milam, C. D.; Farris, J. L.; Dwyer, F. J.; Hardesty, D. K.



Coexistence of two freshwater turtle species along a Mediterranean stream: The role of spatial and temporal heterogeneity  

Microsoft Academic Search

In the Iberian Peninsula the European pond turtle (Emys orbicularis) and the Mediterranean pond turtle (Mauremys leprosa) share many freshwater habitats, in particular Mediterranean streams. Whether and how these two species divide space within those habitats is poorly known in part due to the very low abundance of E. orbicularis at most syntopic sites. The spatial coexistence of these two

Pedro Segurado; Diogo Figueiredo



Hidden biodiversity in an ecologically important freshwater amphipod: differences in genetic structure between two cryptic species.  


Cryptic species, i.e. species that are morphologically hard to distinguish, have been detected repeatedly in various taxa and ecosystems. In order to evaluate the importance of this finding, we have to know in how far cryptic species differ in various aspects of their biology. The amphipod Gammarus fossarum is a key invertebrate in freshwater streams and contains several cryptic species. We examined the population genetic structure, genetic diversity and demographic history of two of them (type A and type B) using microsatellite markers and asked whether they show significant differences. We present results of population genetic analyses based on a total of 37 populations from the headwaters of two major European drainages, Rhine and Rhone. We found that, in both species, genetic diversity was geographically structured among and within drainages. For type A in the Rhine and type B in the Rhone, we detected significant patterns of isolation by distance. The increase of genetic differentiation with geographical distance, however, was much higher in type A than in type B. This result indicates substantial interspecific differences in population history and/or the extent of current gene flow between populations. In the Rhine, type B does not show evidence of isolation by distance, and population differentiation is relatively low across hundreds of kilometres. The majority of these populations also show signatures of recent bottlenecks. These patterns are consistent with a recent expansion of type B into the Rhine drainage. In summary, our results suggest considerable and previously unrecognized interspecific differences in the genetic structure of these cryptic keystone species. PMID:23967060

Westram, Anja Marie; Jokela, Jukka; Keller, Irene



Coaggregation by the Freshwater Bacterium Sphingomonas natatoria Alters Dual-Species Biofilm Formation?  

PubMed Central

Coaggregation is hypothesized to enhance freshwater biofilm development. To investigate this hypothesis, the ability of the coaggregating bacterium Sphingomonas natatoria to form single- and dual-species biofilms was studied and compared to that of a naturally occurring spontaneous coaggregation-deficient variant. Attachment assays using metabolically inactive cells were performed using epifluorescence and confocal laser scanning microscopy. Under static and flowing conditions, coaggregating S. natatoria 2.1gfp cells adhered to glass surfaces to form diaphanous single-species biofilms. When glass surfaces were precoated with coaggregation partner Micrococcus luteus 2.13 cells, S. natatoria 2.1gfp cells formed densely packed dual-species biofilms. The addition of 80 mM galactosamine, which reverses coaggregation, mildly reduced adhesion to glass but inhibited the interaction and attachment to glass-surface-attached M. luteus 2.13 cells. As opposed to wild-type coaggregating cells, coaggregation-deficient S. natatoria 2.1COGgfp variant cells were retarded in colonizing glass and did not interact with glass-surface-attached M. luteus 2.13 cells. To determine if coaggregation enhances biofilm growth and expansion, viable coaggregating S. natatoria 2.1gfp cells or the coaggregation-deficient variant S. natatoria 2.1COGgfp cells were coinoculated in flow cells with viable M. luteus 2.13 cells and allowed to grow together for 96 h. Coaggregating S. natatoria 2.1gfp cells outcompeted M. luteus 2.13 cells, and 96-h biofilms were composed predominantly of S. natatoria 2.1gfp cells. Conversely, when coaggregation-deficient S. natatoria 2.1COGgfp cells were coinoculated with M. luteus 2.13 cells, the 96-h biofilm contained few coaggregation-deficient S. natatoria 2.1 cells. Thus, coaggregation promotes biofilm integration by facilitating attachment to partner species and likely contributes to the expansion of coaggregating S. natatoria 2.1 populations in dual-species biofilms through competitive interactions.

Min, K. R.; Rickard, A. H.



Habitat characteristics for different freshwater snail species as determined biologically through macroinvertebrate information.  


Macro-invertebrates including freshwater snails collected from 643 sites over 8 successive seasons among the River Nile, branches, main canals and certain drains in eight Egyptian Governorates. Thirteen snail species and one bivalve species were identified. The most distributed were Lanistus carinatus and Physa acuta while the most abundant were Cleopatra bulimoides and Physa acuta during the whole study. The sites that harbored each snail species in all the examined water-courses were grouped seasonally and their biological assessment was determined by their minimum and maximum total point similarity percentage to that of the corresponded reference site and mean of the total points. Habitats for most snail species attained minimum total point's similarity percentage less than 21% (very poor habitat) during autumn and winter then spring while during summer very poor habitat was harbored by only few snail species. P. acuta was the only survived snails in habitat which attained 0 as a minimum total point's similarity percentage during two seasons and L. carinatus and Succinea cleopatra during one season. With respect to medically important snails very poor sites constituted 23% of Biomphalaria alexandrina sites, 14% of Lymnaea natalensis and 9.4% of Bulinus truncatus sites. The studied macroinvertebrate matrices, total number of organisms, taxa richness, the Ephemeroptera, Plecoptera, and Trichoptera (EPT) index, ratio of EPT index to chironomidae, ratio of scraper to filtering collector, contribution of dominant macroinvertebrate major group, comparison revealed descending tolerances from B. alexanrina followed by L. natalensis then B. truncates, but Hilsenhoff Biotic Index (HBI) showed the same tolerance to organic pollution. PMID:22435158

El-Khayat, Hanaa M M; Mahmoud, Kadria M A; Mostafa, Bayomy B; Tantawy, Ahmad A; El-Deeb, Fatma A; Ragb, Fawzy M; Ismail, Nahed M; El-Said, Kalil M; Taleb, Hoda M Abu



Eukaryotes in Arctic and Antarctic cyanobacterial mats.  


Cyanobacterial mats are commonly found in freshwater ecosystems throughout the polar regions. Most mats are multilayered three-dimensional structures with the filamentous cyanobacteria embedded in a gel-like matrix. Although early descriptions mentioned the presence of larger organisms including metazoans living in the mats, there have been few studies specifically focused on the microbial eukaryotes, which are often small cells with few morphological features suitable for identification by microscopy. Here, we applied 18S rRNA gene clone library analysis to identify eukaryotes in cyanobacterial mat communities from both the Antarctic and the extreme High Arctic. We identified 39 ribotypes at the level of 99% sequence similarity. These consisted of taxa within algal and other protist groups including Chlorophyceae, Prasinophyceae, Ulvophyceae, Trebouxiophyceae, Bacillariophyceae, Chrysophyceae, Ciliophora, and Cercozoa. Fungi were also recovered, as were 21 metazoan ribotypes. The eukaryotic taxa appeared habitat-specific with little overlap between lake, pond, and ice shelf communities. Some ribotypes were common to both Arctic and Antarctic mats, suggesting global dispersal of these taxa and similarity in the environmental filters acting on protist communities. Many of these eukaryotic taxa likely benefit from protected, nutrient-rich microhabitats within the cyanobacterial mat environment. PMID:22630054

Jungblut, Anne D; Vincent, Warwick F; Lovejoy, Connie



Sensitivity Analysis of a Cyanobacterial Growth and Movement Model under Two Different Flow Regimes  

Microsoft Academic Search

Bloom-forming and toxin-producing cyanobacteria remain a persistent nuisance across the world. Modelling cyanobacterial behaviour\\u000a in freshwaters is an important tool for understanding their population dynamics and predicting the location and timing of\\u000a the bloom events in lakes, reservoirs and rivers. A new deterministic–mathematical model was developed, which simulates the\\u000a growth and movement of cyanobacterial blooms in river systems. The model

Basak Guven; Alan Howard


Sodium Chloride-Induced Volume Changes of Freshwater Cyanobacterium Synechococcus sp. PCC 7942 Cells Can Be Probed by Chlorophyll a Fluorescence  

Microsoft Academic Search

Freshwater species of the cyanobacterial genus Synechococcus import NaCl passively, and export Na+ actively, by means of primary and secondary extrusion mechanisms. As a result of the ion and water fluxes, cell volumes are enlarged. We show in this paper that the NaCl-induced volume enlargement of Synechococcus sp. PCC 7942 cells is attended by a rapid (k = 0.39 s?1)

Kostas Stamatakis; Nectarios P. Ladas; Aikaterini Alygizaki-Zorba; George C. Papageorgiou



A new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) from freshwater fishes in the south-west of Western Australia  

Microsoft Academic Search

A new species of Dermoergasilus Ho & Do, 1982 is described from freshwater fish hosts in the south west of Western Australia. D. occidentalis n. sp. differs from previously described species in the genus principally by the armature of the legs. The new species was\\u000a found on the gills of the freshwater cobbler Tandanus bostocki Whitely and western minnow Galaxias occidentalis Ogilby in

Marina Hassan; Brian Jones; Alan J. Lymbery



Species diversity of freshwater hyphomycetes in some streams of Pakistan. Comparison of sampling techniques  

Microsoft Academic Search

Freshwater hyphomycete communities in four streams were sampled by filtration of water samples, trapping conidia in artificial foam, and examination of alder leaf pack baits and random sampling of naturally occurring submerged leaves. No two communities of freshwater hyphomycetes detected by different sampling techniques used singly in a stream showed 100% similarity. Based on relative frequency values, the same 10

Syed Hussain Iqbal



Chronic toxicity of chloride to freshwater species: effects of hardness and implications for water quality guidelines.  


Toxicity tests using nine freshwater species (Ceriodaphnia dubia, Daphnia magna, Oncorhynchus mykiss, Pimephales promelas, Lumbriculus variegatus, Tubifex tubifex, Chironomus dilutus, Hyallela azteca, and Brachionus calyciflorus) were conducted to evaluate their sensitivity to chloride. Acute-to-chronic ratios (ACRs) from these tests indicate the ACR of 7.59 employed by the United States Environmental Protection Agency (U.S. EPA) in deriving its water quality guideline for chloride may be conservative; a revised ACR of 3.50 is presented here. The endpoints used to calculate the ACR included 24-h to 96-h median lethal concentrations (LC50s) for acute tests, and 48-h to 54-d inhibition concentration (ICx) values for growth or reproduction for chronic exposures. Data from the present chronic toxicity tests, and other investigators, were used to propose a water quality guideline for long-term exposure to chloride using a species sensitivity distribution (SSD) approach. The 5th percentile from the SSD was calculated as 307?mg/L and proposed as the water quality guideline. Cladocerans were the most sensitive species in the dataset. Ceriodaphnia dubia was used to evaluate the relationship between water hardness and sensitivity to chloride. A strong relationship was observed and was used to establish a hardness-related equation to modify the proposed water quality guideline on the basis of water hardness, resulting in values ranging from 64?mg/L chloride at 10?mg/L hardness to 388?mg/L chloride at 160?mg/L hardness (as CaCO?). These data suggest that current water quality guidelines for chloride may be overly conservative in water with moderate-to-high hardness, and may not be sufficiently protective under soft-water conditions. PMID:20872898

Elphick, James R F; Bergh, Kelli D; Bailey, Howard C



Where are all the fish: potential of biogeographical maps to project current and future distribution patterns of freshwater species.  


The dendritic structure of river networks is commonly argued against use of species atlas data for modeling freshwater species distributions, but little has been done to test the potential of grid-based data in predictive species mapping. Using four different niche-based models and three different climate change projections for the middle of the 21st century merged pairwise as well as within a consensus modeling framework, we studied the variability in current and future distribution patterns of 38 freshwater fish species across Germany. We used grid-based (11×11 km) fish distribution maps and numerous climatic, topographic, hydromorphologic, and anthropogenic factors derived from environmental maps at a finer scale resolution (250 m-1 km). Apart from the explicit predictor selection, our modeling framework included uncertainty estimation for all phases of the modeling process. We found that the predictive performance of some niche-based models is excellent independent of the predictor data set used, emphasizing the importance of a well-grounded predictor selection process. Though important, climate was not a primary key factor for any of the studied fish species groups, in contrast to substrate preferences, hierarchical river structure, and topography. Generally, distribution ranges of cold-water and warm-water species are expected to change significantly in the future; however, the extent of changes is highly uncertain. Finally, we show that the mismatch between the current and future ranges of climatic variables of more than 90% is the most limiting factor regarding reliability of our future estimates. Our study highlighted the underestimated potential of grid cell information in biogeographical modeling of freshwater species and provides a comprehensive modeling framework for predictive mapping of species distributions and evaluation of the associated uncertainties. PMID:22792361

Markovic, Danijela; Freyhof, Jörg; Wolter, Christian



Comparison of two freshwater turtle species as monitors of radionuclide and chemical contamination: DNA damage and residue analysis  

Microsoft Academic Search

Two species of turtles that occupy different ecological niches were compared for their usefulness as monitors of freshwater ecosystems where both low-level radioactive and nonradioactive contaminants are present. The pond slider (Trachemys scripta) and common snapping turtle (Chelydra serpentina) were analyzed for the presence of [sup 90]Sr, [sup 137]Cs, [sup 60]Co, and Hg, radionuclides and chemicals known to be present

L. Meyers-Schoene; Lee R. Shugart; John J. Beauchamp; Barbara T. Walton



Do estuaries act as saline bridges to allow invasion of new freshwater systems by non-indigenous fish species?  

Microsoft Academic Search

In Europe, the non-indigenous species (NIS) most frequently introduced are freshwater fish (Garc?a-Berthou et al. 2005). Once introduced, dispersal is a key element in determining their invasiveness (Rehage and Sih 2004); in order to\\u000a limit or mitigate impacts, an understanding of likely establishment and rates and routes for dispersion is important (Pihlaja\\u000a et al. 1998, Ricciardi and Rasmussen 1998). Currently,

J. Anne Brown; Dawn M. Scott; Rod W. Wilson


Molecular identification, typing and traceability of cyanobacteria from freshwater reservoirs.  


In order to assess the potential of several molecular targets for the identification, typing and traceability of cyanobacteria in freshwater reservoirs, molecular techniques were applied to 118 cyanobacterial isolates mostly sourced from Portuguese freshwater reservoirs and representative of three orders of cyanobacteria: Chroococcales (54), Oscillatoriales (15) and Nostocales (49). The isolates were previously identified by morphological methods and subsequently characterized by composite hierarchical cluster analysis of STRR and LTRR (short and long tandemly repeated repetitive sequences) PCR fingerprinting profiles. Representative isolates were selected from each cluster and their molecular identification, at the species level, was obtained or confirmed by phylogenetic positioning using 16S rRNA gene and rpoC1 phylogenies. A highly congruent association was observed between STTR- and LTRR-based clusters and taxonomic affiliation, revealing the usefulness of such PCR fingerprinting profiles for the identification of cyanobacteria. Composite analysis of hierarchical clustering of M13 and ERIC PCR fingerprints also appeared suitable for strain typing and traceability within a reservoir, indicating its potential for use in cyanobacterial monitoring, as a quality management control. Based on Simpson (D) and Shannon-Wiener (J') indices a high diversity was observed within all species, with Planktothrix agardhii showing the lowest diversity values (D=0.83; J'=0.88) and Aphanizomenon flos-aquae the highest ones (D=J'=0.99). A diagnostic key based on 16S-ARDRA, ITS amplification and ITS-ARDRA for identification purposes is also presented. PMID:19202113

Valério, Elisabete; Chambel, Lélia; Paulino, Sérgio; Faria, Natália; Pereira, Paulo; Tenreiro, Rogério



Using ecological-niche modeling as a conservation tool for freshwater species: live-bearing fishes in central Mexico.  


Ecological-niche modeling is an important tool for conservation assessment of terrestrial species; however, its applicability has been poorly explored in the aquatic realm. Goodeines are a monophyletic group of viviparous freshwater fishes that are well known in central Mexico, with 41 species in 19 genera. Given the number of threats to biodiversity in the region, goodeines represent an excellent model with which to test novel conservation approaches. We assessed the conservation status of the goodeines (37 species), based on their potential distributions predicted by ecological-niche models generated with the genetic algorithm for rule-set prediction (GARP). Predictions of species' distributions performed well in six out of eight species for which sufficient information was available to perform estimations of the area under the curve (AUC) in receiver operating characteristic plots. Extensive field surveys conducted in recent years in most cases confirm the models' predictions. Species richness exhibited a nested pattern, in which the number of species increased toward the center of the distribution of the group. At the basin level, the Río Ameca Basin had the highest number of species (11), chiefly because of the high number of microendemic species (6). Human activities within water bodies (e.g., extensive aquaculture) and drainages (e.g., agriculture, ranching, industrial activities) have affected most goodeines severely, given the deleterious effects of pollution and introductions of exotic species, such as carp (Cyprinus carpio, Ctenopharingodon idella) and tilapia (Oreochromis spp.). Our results paint a pessimistic picture for the long-term survival of many goodeines in their natural environment, and realistic conservation measures are complex and would require immediate protection of specific areas that we have identified. Ecological-niche modeling is a suitable tool for conservation assessment of freshwater species, but availability of environmental information on aquatic systems (e.g., temperature, water speed, pH, oxygen concentration) would improve distributional predictions. PMID:17181808

Domínguez-Domínguez, Omar; Martínez-Meyer, Enrique; Zambrano, Luis; De León, Gerardo Pérez-Ponce



Five new species of Acanthobothrium (Tetraphyllidea: Onchobothriidae) from the freshwater stingray Himantura chaophraya (Batoidea: Dasyatidae) in Malaysian Borneo.  


Five new species of Acanthobothrium (Tetraphyllidea: Onchobothriidae) are described from the spiral intestine of the Freshwater whipray, Himantura chaophraya, in the Kinabatangan River in Malaysian Borneo. Based on criteria set forth in a previous categorization scheme for species of Acanthobothrium, these consist of 3 Category 1 species, Acanthobothrium asnihae n. sp., Acanthobothrium saliki n. sp., and Acanthobothrium zainali n. sp.; a Category 8 species, Acanthobothrium etini n. sp.; and a Category 2 species, Acanthobothrium masnihae n. sp.. Acanthobothrium asnihae n. sp. differs from all Category 1 species in its possession of a horizontal band of weak musculature that divides the posterior loculus in half. Among Category 1 species, A. saliki n. sp. differs from all but Acanthobothrium southwelli in its possession of postovarian testes. It differs from A. southwelli in its possession of fewer testes and a greater number of proglottids. Acanthobothrium zainali n. sp. differs from the 25 other Category 1 species in a combination of overall size, muscular pad and hook shape, arrangement and number of testes, ovary configuration in cross section, position of ovarian isthmus, and genital pore position. Acanthobothrium etini n. sp. is distinguished from all 5 other Category 8 species in its lack of testes from the proglottid antiporal and postporal regions and in testis number. Acanthobothrium masnihae n. sp. differs from the 35 other Category 2 species in its possession of fewer testes, postporal testes, or a greater number of proglottids. A key to Acanthobothrium species parasitizing H. chayophraya is presented. This represents the first report of Acanthobothrium from freshwater stingrays belonging to a family other than the Potamotrygonidae. PMID:16629324

Fyler, C A; Caira, J N



Exploiting cyanobacterial P450 pathways.  


Cytochrome P450s are hemoprotein oxygenases involved in natural product synthetic pathways. Cyanobacteria are oxygenic photosynthetic microorganisms and are considered a rich source of natural products, and are now known to harbour P450s. A variety of cyanobacterial species have been found to contain multiple copies of P450s in their genomes, and over 100 have been predicted. Interestingly, some are membrane-bound as in eukaryotes, as opposed to cytoplasmic in bacteria. Furthermore, they can complement plant P450s and perform bioremediation of oil spills by the breakdown of alkanes. Functional expression of a selection Nostoc spp. P450s in Escherichia coli, with associated enzymes, has successfully produced the sesquiterpenes--germacradienol, germacrene and B-elemene, although others have failed for undetermined reasons. PMID:20299274

Robert, Faith O; Pandhal, Jagroop; Wright, Phillip C



Morphological and Phylogenetic Characterizations of Freshwater Thioploca Species from Lake Biwa, Japan, and Lake Constance, Germany  

PubMed Central

Filamentous, gliding, sulfide-oxidizing bacteria of the genus Thioploca were found on sediments in profundal areas of Lake Biwa, a Japanese freshwater mesotrophic lake, and were characterized morphologically and phylogenetically. The Lake Biwa Thioploca resembled morphologically Thioploca ingrica, a brackish water species from a Danish fjord. The diameters of individual trichomes were 3 to 5.6 ?m; the diameters of complete Thioploca filaments ranged from 18 to 75 ?m. The cell lengths ranged from 1.2 to 3.8 ?m. In transmission electron microscope specimens stained with uranyl acetate, dense intracellular particles were found, which did not show any positive signals for phosphorus and sulfur in an X-ray analysis. The 16S rRNA gene of the Thioploca from Lake Biwa was amplified by using newly designed Thioploca-specific primers (706-Thioploca, Biwa160F, and Biwa829R) in combination with general bacterial primers in order to avoid nonspecific amplification of contaminating bacterial DNA. Denaturing gradient gel electrophoresis (DGGE) analysis of the three overlapping PCR products resulted in single DGGE bands, indicating that a single 16S rRNA gene had been amplified. With the same method, the Thioploca from Lake Constance was examined. The 16S rRNA sequence was verified by performing fluorescence in situ hybridization targeted at specific motifs of the Lake Biwa Thioploca. Positive signals were obtained with the bacterial probe EUB-338, the ?-proteobacterial probe GAM42a, and probe Biwa829 targeting the Lake Biwa Thioploca. Based on the nearly complete 16S rRNA sequence and on morphological similarities, the Thioploca from Lake Biwa and the Thioploca from Lake Constance are closely related to T. ingrica and to each other.

Kojima, Hisaya; Teske, Andreas; Fukui, Manabu



Cyanobacterial hydrogen production  

Microsoft Academic Search

With the global attention and research now being focussed on looking for an alternative to fossil fuel, hydrogen is the hope\\u000a of future. Cyanobacteria are highly promising microorganisms for biological photohydrogen production. The review highlights\\u000a the advancement in the biology of cyanobacterial hydrogen production in recent years. It discusses the enzymes involved in\\u000a hydrogen production, viz. hydrogenases and nitrogenases, various

Datta Madamwar; Nikki Garg; Vishal Shah



Antarctic Micrometazoa: Fresh-Water Species in the McMurdo Sound Area.  


The multicellular microfauna in fresh-water bodies of Ross Island and the nearby continental coast of Victoria Land is strikingly impoverished with respect to major groups. Yet there are thriving populations belonging to the Rotifera, Nematoda, Tardigrada, and Turbellaria. PMID:17829546

Dougherty, E C; Harris, L G



Haematophagous feeding of newly metamorphosed European sea lampreys Petromyzon marinus on strictly freshwater species.  


Approximately 6% of the freshwater living northern straight-mouth nase Pseudochondrostoma duriense in two Spanish rivers had attached post-metamorphic sea lamprey Petromyzon marinus. Minimum prey size was 16·1?cm fork length and 56·3?g mass. The condition factor of attacked P. duriense was 16% lower than that of unattacked conspecifics. PMID:23639169

Silva, S; Servia, M J; Vieira-Lanero, R; Nachón, D J; Cobo, F



Studies on the Seasonal Life History of Three Species of Freshwater Ostracoda  

Microsoft Academic Search

1. The literature reveals no strictly seasonal life-history studies for North American freshwater Ostracoda. 2. Over 400 collections of ostracods were taken from Round Lake (artificial pond) for more than fifteen months (April 7, 1941-July 15, 1942) in order to keep variable factors at a minimum. The habitat, located in Forest Park, St. Louis, Mo., is fed primarily by city

Edward Ferguson Jr.



Concentration of cadmium, copper, lead, and zinc in six species of freshwater clams  

Microsoft Academic Search

Reports of the occurrence and accumulation of heavy metals in pelecypods have generally been limited to salt water forms (AYLING, 1974; iRELAND, 1973; KOPFLER and MAYER, 1973; PENTREATH, 1973; VALIELA and BANUS, 1974; WINDOM and SMITH, 1972). This is apparently due to the concern over contamination of commercial oyster and mussel beds. Few reports of heavy metal concentrations in freshwater

Richard V. Anderson



Habitat Use of Twenty-Five Common Species of Oregon Freshwater Fishes.  

National Technical Information Service (NTIS)

The study had two objectives. The first was to determine the use of the physical habitat by the 25 most common native freshwater fishes of Oregon, and the second was to evaluate the use of a large computer database of museum records in the determination. ...

C. E. Bond E. Rexstad R. M. Hughes




EPA Science Inventory

This study had two objectives. he first was to determine the use of the physical habitat by the 25 most common native freshwater fishes of Oregon, and the second was to evaluate the use of a large computer database of museum records in the determination. he database encompasses 2...


Species composition and cyanotoxin production in periphyton mats from three lakes of varying trophic status.  


In lakes, benthic micro-algae and cyanobacteria (periphyton) can contribute significantly to total primary productivity and provide important food sources for benthic invertebrates. Despite recognition of their importance, few studies have explored the diversity of the algal and cyanobacterial composition of periphyton mats in temperate lakes. In this study, we sampled periphyton from three New Zealand lakes: Tikitapu (oligotrophic), ?k?reka (mesotrophic) and Rotoiti (eutrophic). Statistical analysis of morphological data showed a clear delineation in community structure among lakes and highlighted the importance of cyanobacteria. Automated rRNA intergenic spacer analysis (ARISA) and 16S rRNA gene clone libraries were used to investigate cyanobacterial diversity. Despite the close geographic proximity of the lakes, cyanobacterial species differed markedly. The 16S rRNA gene sequence analysis identified eight cyanobacterial OTUs. A comparison with other known cyanobacterial sequences in GenBank showed relatively low similarities (91-97%). Cyanotoxin analysis identified nodularin in all mats from Lake Tikitapu. ndaF gene sequences from these samples had very low (? 89%) homology to sequences in other known nodularin producers. To our knowledge, this is the first detection of nodularin in a freshwater environment in the absence of Nodularia. Six cyanobacteria species were isolated from Lake Tikitapu mats. None were found to produce nodularin. Five of the species shared low (< 97%) 16S rRNA gene sequence similarities with other cultured cyanobacteria. PMID:22092304

Wood, Susie A; Kuhajek, Jeannie M; de Winton, Mary; Phillips, Ngaire R



Mitochondrial 12S rRNA sequences support the existence of a third species of freshwater blackfish (Percicthyidae: Gadopsis) from south-eastern Australia  

Microsoft Academic Search

Miller, A.D., Waggy, G., Ryan, S.G., and Austin, C.M. 2004. Mitochondrial 12S rRNA sequences support the existence of a third species of freshwater blackfish (Percicthyidae: Gadopsis) from south-eastern Australia. Memoirs of Museum Victoria 61(2): 121-127. Fish of the genus Gadopsis are a distinctive component of the freshwater fish fauna of south-eastern Australia. Gadopsis marmoratus and G. bispinosus are the only




Simultaneous multiple species testing: Acute toxicity of 13 chemicals to 12 diverse freshwater amphibian, fish, and invertebrate families  

Microsoft Academic Search

This test series developed methods for testing a compliment of aquatic organisms in a single test that satisfies the freshwater acute toxicity requirements for setting water quality criteria. Species tested included fathead minnowsPimephales promelas, rainbow troutSalmo gairdneri, bluegillLepomis macrochirus, channel catfishIctalurus punctatus, goldfishCarassius auratus, white suckerCatostomus commersoni, daphnidDaphnia magna, midgeTanytarsus dissimilis, crayfishOrconectes immunis, snailAplexa hypnorum, tadpoleXenopus laevis, and leechNephelopsis obscura.

Gary W. Holcombe; Gary L. Phipps; Abdul H. Sulaiman; Alex D. Hoffman



Gene expression and activity of digestive proteases in Daphnia: effects of cyanobacterial protease inhibitors  

Microsoft Academic Search

BACKGROUND: The frequency of cyanobacterial blooms has increased worldwide, and these blooms have been claimed to be a major factor leading to the decline of the most important freshwater herbivores, i.e. representatives of the genus Daphnia. This suppression of Daphnia is partly attributed to the presence of biologically active secondary metabolites in cyanobacteria. Among these metabolites, protease inhibitors are found

Anke Schwarzenberger; Anja Zitt; Peter Kroth; Stefan Mueller; Eric Von Elert



The role of reactive oxygen species in microcystin-LR-induced DNA damage  

Microsoft Academic Search

Microcystins are cyclic heptapeptides produced by different freshwater cyanobacterial species such as Microcystis aeruginosa. They have been shown to induce DNA damage in vitro and in vivo, however, the mechanisms of their genotoxic activity remain unclear. With the comet assay we demonstrate that, in human hepatoma HepG2 cells, microcystin-LR (MCLR) induced DNA strand breaks which were transiently present and probably

Bojana Žegura; Tamara T Lah; Metka Filipi?



A preliminary study of oligochaetes in Poyang Lake, the largest freshwater lake of China, and its vicinity, with description of a new species of Limnodrilus  

Microsoft Academic Search

The oligochaete fauna of the largest freshwater lake of China, Poyang Lake, has never been investigated before. On the basis of a preliminary survey in the lake and its vicinity in 1997–1999, 25 species belonging to 20 genera and 5 families are recorded. Among them, one genus, Cernosvitoviella (Enchytraeidae), and two species, Bratislavia unidentata (Naididae), Potamothrix bedoti (Tubificidae), are recorded

Hongzhu Wang; Yanling Liang



Susceptibility of 7 freshwater gastropod species in Zimbabwe to infection with Gastrodiscus aegyptiacus (Cobbold, 1876) Looss, 1896.  


Gastrodiscosis outbreaks due to Gastrodiscus aegyptiacus were recorded in horses in the vicinity of Harare, Zimbabwe, in the absence of Bulinus forskalii, B. senegalensis and Cleopatra sp. which are considered to be the only intermediate host snails. This suggested the possibility of other snail species acting as intermediate hosts in the life cycle of the trematode. A study was carried out to determine the susceptibility of 7 freshwater snail species to infection with G. aegyptiacus. First generation (F-1) of 5 freshwater pulmonate snail species, Bulinus tropicus, Bulinus globosus, Biomphalaria pfeifferi, Helisoma dyuri and Physa acuta that were bred in the laboratory, and 2 prosobranch snail species, Melanoides tuberculata and Cleopatra sp. that were collected from the field were used in this study. Data pertaining to mortalities and cercariae shedding were recorded throughout the experimental period. The prosobranch snails, M. tuberculata and Cleopatra sp. were susceptible to G. aegyptiacus with a minimum prepatent period of 45 days and 54 days, respectively. Bulinus tropicus, P. acuta and H. duryi were susceptible as evidenced by the presence of different generations of rediae and mature cercariae on dissection at 59 days post-infection although attempts to induce the snails to shed from 28 days post-infection did not produce cercariae. Bulinus globosus and Bio. pfeifferi were refractory to infection. The results revealed the ability of G. aegyptiacus to infect M. tuberculata, Cleopatara sp., B. tropicus, P. acuta and H. duryi under experimental conditions and this may explain the recorded outbreaks of gastrodiscosis in equine populations in Zimbabwe in the absence of the known intermediate hosts. Bulinus tropicus is considered as the most likely major intermediate host of G. aegyptiacus because of its wide distribution in Zimbabwe and is well adapted to a wide variety of environments. PMID:15830604

Mukaratirwa, S; Munjere, I F; Takawira, M; Chingwena, G



Major ion toxicity of six produced waters to three freshwater species: Application of ion toxicity models and TIE procedures  

SciTech Connect

Previous research to characterize the acute toxicity of major ions to freshwater organisms resulted in the development of statistical toxicity models for three freshwater species (Ceriodaphnia dubia, Pimephales promelas, and Daphnia magna). These ion toxicity models estimate the toxicity of seven major ions utilizing logistic regression. In this study, the ion toxicity models were used in conjunction with Phase 1 toxicity identification evaluation (TIE) procedures to evaluate the contribution of major ion toxicity to the total toxicity of six produced water samples ranging in total salinity from 1.7 to 58.1 g/L. Initial toxicities of all six samples were compared to the model predictions. Four produced waters were found to have toxicity consistent with toxicity attributable to major ion concentrations only. Two produced waters were found to exhibit more toxicity than expected from ion concentrations alone. These samples were subjected to Phase 1 TIE procedures. Toxicities were reduced by specific Phase 1 TIE manipulations to those predicted by the ion toxicity models. Mock effluents were used to verify the results. The combination of the ion toxicity models with Phase 1 TIE procedures successfully quantified the toxicity due to major ions in six produced water samples.

Tietge, J.E.; Hockett, J.R. [ENSR Consulting and Engineering, Fort Collins, CO (United States); Evans, J.M. [Gas Research Inst., Chicago, IL (United States)



Coastal Estuaries as Habitat for a Freshwater Fish Species: Exploring Population-Level Effects of Salinity on Largemouth Bass  

Microsoft Academic Search

Estuaries are systems where marine and freshwaters interface. The largemouth bass Micropterus salmoides is a freshwater predator commonly found in the oligohaline portions of estuaries in coastal North America. As a popular recreational sport fish in estuaries, largemouth bass are caught in large numbers, but large (?2.3-kg) individuals are rarer than in inland (freshwater) systems. A pervasive factor affecting estuarine

Alicia J. Norris; Dennis R. DeVries; Russell A. Wright



Differential responses of the freshwater wetland species Juncus effusus L. and Caltha palustris L. to iron supply in sulfidic environments.  


Sulfur pollution can lead to serious problems in freshwater wetlands, including phosphorus eutrophication and sulfide toxicity. We tested the effects of anaerobic iron-rich groundwater discharge in fens, simulated by iron injection, on two characteristic species (Juncus effusus and Caltha palustris) in a sulfidic environment. Biomass production of C. palustris roots showed an optimum response to the combined addition of iron and sulfide, with highest values at intermediate concentrations of both substances. Iron deficiency apparently occurred at low iron concentrations, while at high iron concentrations, growth was decreased. For J. effusus, in contrast, no toxic effects were found of both iron and sulfide. This could be explained by larger radial oxygen loss (ROL) of J. effusus and could not be explained by differences in phosphorous concentrations. The results of our experiments confirm that iron-rich groundwater discharge has the potential to affect vegetation composition through toxicity modification in sulfidic environments. PMID:17070634

Van der Welle, Marlies E W; Niggebrugge, Karla; Lamers, Leon P M; Roelofs, Jan G M



Insights from Cyanobacterial Genomes for the Development of Extraterrestrial Photoautotrophic Biotechnologies  

NASA Astrophysics Data System (ADS)

Using genomic and metagenomic analysis, Fe-tolerant cyanobacterial species with a large and diverse set of stress-tolerant genes, were identified as prime candidates for in situ resource utilization in a biogeoreactor at extraterrestrial outposts.

Brown, I. I.; Bryant, D. A.; Tringe, S. G.; Malley, K.; Sosa, O.; Sarkisova, S. A.; Garrison, D. H.; McKay, D. S.



Toxicity and recovery in the pregnant mouse after gestational exposure to the cyanobacterial toxin, cylindrospermopsin.  

EPA Science Inventory

Cylindrospermopsin (CYN) is a tricyclic alkaloid toxin produced by fresh water cyanobacterial species worldwide. CYN has been responsible for both livestock and human poisoning after oral exposure. This study investigated the toxicity of CYN to pregnant mice exposed during differ...


Genome Sequences of Two Freshwater Betaproteobacterial Isolates, Limnohabitans Species Strains Rim28 and Rim47, Indicate Their Capabilities as Both Photoautotrophs and Ammonia Oxidizers  

PubMed Central

Betaproteobacterial genus Limnohabitans represents an important part of freshwater bacterioplankton. Here, we report genome sequences of two Limnohabitans isolates, Rim28 and Rim47. They contain a complete photosynthesis gene cluster, RuBisCO, CO dehydrogenase, ammonia monooxygenase, and sulfur-oxidizing genes, which indicates a great metabolic versatility of the Limnohabitans species.

Zeng, Yonghui; Kasalicky, Vojtech; Simek, Karel



Cyanobacterial diversity and halotolerance in a variable hypersaline environment.  


The Great Salt Plains (GSP) in north-central Oklahoma, USA is an expansive salt flat (approximately 65 km(2)) that is part of the federally protected Salt Plains National Wildlife Refuge. The GSP serves as an ideal environment to study the microbial diversity of a terrestrial, hypersaline system that experiences wide fluctuations in freshwater influx and diel temperature. Our study assessed cyanobacterial diversity at the GSP by focusing on the taxonomic and physiological diversity of GSP isolates, and the 16S rRNA phylogenetic diversity of isolates and environmental clones from three sites (north, central, and south). Taxonomic diversity of isolates was limited to a few genera (mostly Phormidium and Geitlerinema), but physiological diversity based on halotolerance ranges was strikingly more diverse, even between strains of the same phylotype. The phylogenetic tree revealed diversity that spanned a number of cyanobacterial lineages, although diversity at each site was dominated by only a few phylotypes. Unlike other hypersaline systems, a number of environmental clones from the GSP were members of the heterocystous lineage. Although a number of cyanobacterial isolates were close matches with prevalent environmental clones, it is not certain if these clones reflect the same halotolerance ranges of their matching isolates. This caveat is based on the notable disparities we found between strains of the same phylotype and their inherent halotolerance. Our findings support the hypothesis that variable or poikilotrophic environments promote diversification, and in particular, select for variation in ecotype more than phylotype. PMID:17653786

Kirkwood, Andrea E; Buchheim, Julie A; Buchheim, Mark A; Henley, William J



Spatial Distribution of Cryptic Species Diversity in European Freshwater Amphipods (Gammarus fossarum) as Revealed by Pyrosequencing  

Microsoft Academic Search

In order to understand and protect ecosystems, local gene pools need to be evaluated with respect to their uniqueness. Cryptic species present a challenge in this context because their presence, if unrecognized, may lead to serious misjudgement of the distribution of evolutionarily distinct genetic entities. In this study, we describe the current geographical distribution of cryptic species of the ecologically

Anja Marie Westram; Jukka Jokela; Caroline Baumgartner; Irene Keller



Acid and alkaline phosphatase activities and pathological changes induced in Tilapia fish ( Oreochromis sp.) exposed subchronically to microcystins from toxic cyanobacterial blooms under laboratory conditions  

Microsoft Academic Search

The effects of microcystins (MCs) from cyanobacterial cells on the enzymatic activities of acid and alkaline phosphatases (ACP and ALP) from liver, kidney and gill tissues, and the histopathological changes in freshwater Tilapia fish (Oreochromis sp.) were investigated under laboratory conditions. Fish were exposed to cyanobacterial cells (60.0?g MC-LR\\/fish per day) through their diet at different exposure times (14 and

R. Molina; I. Moreno; S. Pichardo; A. Jos; R. Moyano; J. G. Monterde; A. Cameán



Hysterothylacium patagonense n. sp. (Nematoda: Anisakidae) from freshwater fishes in Patagonia, Argentina, with a key to the species of Hysterothylacium in American freshwater fishes  

Microsoft Academic Search

A new anisakid nematode, Hysterothylacium patagonense n. sp., is described from the intestine of the temperate bass Percichthys trucha (Cuvier & Valenciennes), a freshwater fish from Lake Aluminé, Patagonia, Argentina. It is characterised mainly by the absence of lateral alae, the length ratio of the caecum and ventricular appendix (1:0.9–1.8), the length of the spicules (0.952–1.292 mm) and the presence

František Moravec; Shigehiko Urawa; Claudio O. Coria




EPA Science Inventory

Airbome hyperspectral data were used to detect dense patches of Phragmites australis, a native opportunist plant species, at the Pointe Mouillee coastal wetland complex (Wayne and Monroe Counties, Michigan). This study provides initial results from one of thirteen coastal wetland...


Spatial Distribution of Cryptic Species Diversity in European Freshwater Amphipods (Gammarus fossarum) as Revealed by Pyrosequencing  

PubMed Central

In order to understand and protect ecosystems, local gene pools need to be evaluated with respect to their uniqueness. Cryptic species present a challenge in this context because their presence, if unrecognized, may lead to serious misjudgement of the distribution of evolutionarily distinct genetic entities. In this study, we describe the current geographical distribution of cryptic species of the ecologically important stream amphipod Gammarus fossarum (types A, B and C). We use a novel pyrosequencing assay for molecular species identification and survey 62 populations in Switzerland, plus several populations in Germany and eastern France. In addition, we compile data from previous publications (mainly Germany). A clear transition is observed from type A in the east (Danube and Po drainages) to types B and, more rarely, C in the west (Meuse, Rhone, and four smaller French river systems). Within the Rhine drainage, the cryptic species meet in a contact zone which spans the entire G. fossarum distribution range from north to south. This large-scale geographical sorting indicates that types A and B persisted in separate refugia during Pleistocene glaciations. Within the contact zone, the species rarely co-occur at the same site, suggesting that ecological processes may preclude long-term coexistence. The clear phylogeographical signal observed in this study implies that, in many parts of Europe, only one of the cryptic species is present.

Westram, Anja Marie; Jokela, Jukka; Baumgartner, Caroline; Keller, Irene



Effects of pH on Dissolved Organic Matter From Freshwater Algal Species  

NASA Astrophysics Data System (ADS)

Dissolved organic matter (DOM) is ubiquitous in all natural waters. The nature and composition of aquatic DOM depends on its origin (autochthonous vs. allochthonous) and the physical chemical conditions (pH) of the system. It is clear that autochthonous DOM of algal origin is an important contributor to the DOM pool in most aquatic systems. Little is known on its nature and composition. In this study, algal monocultures of S. acutus and F. crotonensis were grown at two different pHs (pH 7 and 5). The production of exudates was monitored over time and characterized by dissolved organic carbon content, absorbance and synchronous fluorescence. Results indicate a significant difference in the concentration of dissolved organic carbon (DOC) formed per species. The ratio of DOC to chlorophyll a is ten times greater in S. acutus than F. crotonensis. In terms of composition, the production of humic-like compounds varies between species with F. crotonensis producing up to four fold more at natural pH. At lower pH, the production of algal DOM is less but there were more proteins and humic materials generated by both species under decreasing pH, with a significant increase in the S. acutus species. Therefore, the concentration and composition of DOM depends not only on algal species but also on the physical chemical condition (pH level) indicating that water acidification would have a major impact on DOM composition.

Kehret, Y.; Gueguen, C.



Freshwater Biological Traits Database.  

National Technical Information Service (NTIS)

The Freshwater Biological Traits Database currently contains traits data for 3,857 North American macroinvertebrate taxa and includes habitat, life history, mobility, morphology, and ecological trait data. Species traits are the characteristics that expla...



Extracellular cyanobacterial substances inhibit microbial growth.  


Cyanobacteria are able to produce extracellular substances with different biological activities and behaviors. The marine cyanobacteria Anabaena sp. strain Hi 26 and Oscillatoria subtilissima strain Bo 62 cause significant color changes in their growth media, while viscosity of the medium is influenced by Rivularia sp. strain Bo 85 and Oscillatoria limnetica strain Flo 1. Sterile-filtered media, pregrown with the organisms mentioned above, were used to study the influence of changes in media bioactivity induced by "excreted substances" on the growth and/or morphological development of five related filamentous cyanobacterial species and on selected heterotrophic microorganisms. Cell lysis, empty sheaths, different lengths of filaments, or even single cells and a decrease in chlorophyll a and protein content were the characteristic changes obtained by such a "cyanobacterial assay." The use of a "precultured" medium, as demonstrated in an "agar diffusion assay," affects in varying degrees the growth of gram-positive and gram-negative heterotrophic bacteria, as well as of the yeast Saccharomyces cerevisiae. PMID:11334306

Heyduck-Söller, B; Fischer, U




EPA Science Inventory

Fish larvae and early juveniles of all species tested (brook trout, rainbow trout, brown trout, lake trout, northern pike, white sucker, herring and smallmouth bass) were more sensitive to copper than the embryos. Embryo survival was affected only at the higher concentrations tes...



EPA Science Inventory

The rationale and conceptual basis for the use of sediment toxicity assays are discussed in relationship to their use in sediment evaluations employing faunal surveys, toxicity assays, and chemical analyses. he disadvantages and advantages of various species from the major classe...


Estimating the financial costs of freshwater invasive species in Great Britain: a standardized approach to invasive species costing  

Microsoft Academic Search

Both ecological and economic impacts factor into invasive alien species (IAS) management considerations; however, economic\\u000a impacts are often difficult to assess, much less quantify. Studies frequently aggregate identified financial costs as a proxy\\u000a for IAS economic impacts, but these aggregate figures are often generated in an ad hoc fashion. Such estimates typically sum\\u000a disparate costs, which might vary with respect

Matthew P. J. OreskaDavid; David C. Aldridge



Competitive interactions during basking between native and invasive freshwater turtle species  

Microsoft Academic Search

The red-eared slider (Trachemys scripta elegans) is currently introduced in many Mediterranean countries, where it behaves as an invasive species that competes and displaces\\u000a native populations of the endangered Spanish terrapin (Mauremys leprosa). However, the nature of competitive interactions is relatively unknown. During basking activity, factors like greater body\\u000a size or pre-existing behavioral adaptations to an original habitat with higher

Nuria Polo-CaviaPilar; Pilar López; José Martín



Distinct migratory and non-migratory ecotypes of an endemic New Zealand eleotrid (Gobiomorphus cotidianus) - implications for incipient speciation in island freshwater fish species  

PubMed Central

Background Many postglacial lakes contain fish species with distinct ecomorphs. Similar evolutionary scenarios might be acting on evolutionarily young fish communities in lakes of remote islands. One process that drives diversification in island freshwater fish species is the colonization of depauperate freshwater environments by diadromous (migratory) taxa, which secondarily lose their migratory behaviour. The loss of migration limits dispersal and gene flow between distant populations, and, therefore, is expected to facilitate local morphological and genetic differentiation. To date, most studies have focused on interspecific relationships among migratory species and their non-migratory sister taxa. We hypothesize that the loss of migration facilitates intraspecific morphological, behavioural, and genetic differentiation between migratory and non-migratory populations of facultatively diadromous taxa, and, hence, incipient speciation of island freshwater fish species. Results Microchemical analyses of otolith isotopes (88Sr, 137Ba and 43Ca) differentiated migratory and non-migratory stocks of the New Zealand endemic Gobiomorphus cotidianus McDowall (Eleotridae). Samples were taken from two rivers, one lake and two geographically-separated outgroup locations. Meristic analyses of oculoscapular lateral line canals documented a gradual reduction of these structures in the non-migratory populations. Amplified fragment length polymorphism (AFLP) fingerprints revealed considerable genetic isolation between migratory and non-migratory populations. Temporal differences in reproductive timing (migratory = winter spawners, non-migratory = summer spawners; as inferred from gonadosomatic indices) provide a prezygotic reproductive isolation mechanism between the two ecotypes. Conclusion This study provides a holistic look at the role of diadromy in incipient speciation of island freshwater fish species. All four analytical approaches (otolith microchemistry, morphology, spawning timing, population genetics) yield congruent results, and provide clear and independent evidence for the existence of distinct migratory and non-migratory ecotypes within a river in a geographically confined range. The morphological changes within the non-migratory populations parallel interspecific patterns observed in all non-migratory New Zealand endemic Gobiomorphus species and other derived gobiid taxa, a pattern suggesting parallel evolution. This study indicates, for the first time, that distinct ecotypes of island freshwater fish species may be formed as a consequence of loss of migration and subsequent diversification. Therefore, if reproductive isolation persists, these processes may provide a mechanism to facilitate speciation.



Factors and processes shaping the population structure and distribution of genetic variation across the species range of the freshwater snail radix balthica (Pulmonata, Basommatophora)  

Microsoft Academic Search

Background  Factors and processes shaping the population structure and spatial distribution of genetic diversity across a species' distribution\\u000a range are important in determining the range limits. We comprehensively analysed the influence of recurrent and historic factors\\u000a and processes on the population genetic structure, mating system and the distribution of genetic variability of the pulmonate\\u000a freshwater snail Radix balthica. This analysis was

Markus Pfenninger; Moritz Salinger; Timm Haun; Barbara Feldmeyer



Interactions of gold nanoparticles with freshwater aquatic macrophytes are size and species dependent.  


The partitioning of 4- and 18-nm gold nanoparticles (AuNPs) to aquatic macrophytes was investigated in vivo with exposure suspension in well water. Three morphologically distinct aquatic macrophytes were studied. Myriophyllum simulans Orch. and Egeria densa Planch. are submerged aquatic vascular plants, whereas Azolla caroliniana Willd. is a free-floating aquatic fern. Because aquatic plants absorb the majority of their nutrients from the water column, it is logical to hypothesize that they may absorb nanomaterials in suspension, potentially facilitating trophic transfer. Each plant was exposed to two different-sized gold nanospheres at a nominal concentration of 250?µg/L AuNPs for 24?h. Macrophytes were harvested at six time points (1, 3, 6, 12, 18, and 24?h), dried, and then analyzed for gold concentration via inductively coupled plasma-mass spectrometry. Concentrations were normalized to whole-plant dry tissue mass. The present study shows that absorption of AuNPs through root uptake was size and species dependent. Electron microscopy revealed that 4- and 18-nm AuNPs adsorbed to the roots of each species. Root tissue was sectioned, and transmission electron microscopy indicated that 4-nm and 18-nm AuNPs were absorbed by A. caroliniana, whereas only 4-nm AuNPs were absorbed by M. simulans. Egeria densa did not absorb AuNPs of either size. Gold nanoparticles were confirmed in tissue by using energy-dispersive X-ray spectroscopy. Absorption of AuNPs by plants may be a function of the salinity tolerance of each species. PMID:22038861

Glenn, J Brad; White, Sarah A; Klaine, Stephen J



Ecophysiological Evidence that Achromatium oxaliferum Is Responsible for the Oxidation of Reduced Sulfur Species to Sulfate in a Freshwater Sediment  

PubMed Central

Achromatium oxaliferum is a large, morphologically conspicuous, sediment-dwelling bacterium. The organism has yet to be cultured in the laboratory, and very little is known about its physiology. The presence of intracellular inclusions of calcite and sulfur have given rise to speculation that the bacterium is involved in the carbon and sulfur cycles in the sediments where it is found. Depth profiles of oxygen concentration and A. oxaliferum cell numbers in a freshwater sediment revealed that the A. oxaliferum population spanned the oxic-anoxic boundary in the top 3 to 4 cm of sediments. Some of the A. oxaliferum cells resided at depths where no oxygen was detectable, suggesting that these cells may be capable of anaerobic metabolism. The distributions of solid-phase and dissolved inorganic sulfur species in the sediment revealed that A. oxaliferum was most abundant where sulfur cycling was most intense. The sediment was characterized by low concentrations of free sulfide. However, a comparison of sulfate reduction rates in sediment cores incubated with either oxic or anoxic overlying water indicated that the oxidative and reductive components of the sulfur cycle were tightly coupled in the A. oxaliferum-bearing sediment. A positive correlation between pore water sulfate concentration and A. oxaliferum numbers was observed in field data collected over an 18-month period, suggesting a possible link between A. oxaliferum numbers and the oxidation of reduced sulfur species to sulfate. The field data were supported by laboratory incubation experiments in which sodium molybdate-treated sediment cores were augmented with highly purified suspensions of A. oxaliferum cells. Under oxic conditions, rates of sulfate production in the presence of sodium molybdate were found to correlate strongly with the number of cells added to sediment cores, providing further evidence for a role for A. oxaliferum in the oxidation of reduced sulfur.

Gray, N. D.; Pickup, R. W.; Jones, J. G.; Head, I. M.



Consideration of exposure and species sensitivity of triclosan in the freshwater environment.  


Triclosan (TCS) is a broad-spectrum antimicrobial used in consumer products including toothpaste and hand soap. After being used, TCS is washed or rinsed off and residuals that are not biodegraded or otherwise removed during wastewater treatment can enter the aquatic environment in wastewater effluents and sludges. The environmental exposure and toxicity of TCS has been the subject of various scientific and regulatory discussions in recent years. There have been a number of publications in the past 5 y reporting toxicity, fate and transport, and in-stream monitoring data as well as predictions from aquatic risk assessments. State-of-the-science probabilistic exposure models, including Geography-referenced Regional Exposure Assessment Tool for European Rivers (GREAT-ER) for European surface waters and Pharmaceutical Assessment and Transport Evalutation (PhATE) for US surface waters, have been used to predict in-stream concentrations (PECs). These models take into account spatial and temporal variability in river flows and wastewater emissions based on empirically derived estimates of chemical removal in wastewater treatment and in receiving waters. These model simulations (based on realistic use levels of TCS) have been validated with river monitoring data in areas known to be receiving high wastewater loads. The results suggest that 90th percentile (low flow) TCS concentrations are less than 200 ng/L for the Aire-Calder catchment in the United Kingdom and between 250 ng/L (with in-stream removal) and 850 ng/L (without in-stream removal) for a range of US surface waters. To better identify the aquatic risk of TCS, a species sensitivity distribution (SSD) was constructed based on chronic toxicity values, either no observed effect concentrations (NOECs) or various percentile adverse effect concentrations (EC10-25 values) for 14 aquatic species including fish, invertebrates, macrophytes, and algae. The SSD approach is believed to represent a more realistic threshold of effect than a predicted no effect concentration (PNEC) based on the data from the single most sensitive species tested. The log-logistic SSD was used to estimate a PNEC, based on an HC5,50 (the concentration estimated to affect the survival, reproduction and/or growth of 5% of species with a 50% confidence interval). The PNEC for TCS was 1,550 ng/L. Comparing the SSD-based PNEC with the PECs derived from GREATER and PhATE modeling to simulate in-river conditions in Europe and the United States, the PEC to PNEC ratios are less than unity suggesting risks to pelagic species are low even under the highest likely exposures which would occur immediately downstream of wastewater treatment plant (WWTP) discharge points. In-stream sorption, biodegradation, and photodegradation will further reduce pelagic exposures of TCS. Monitoring data in Europe and the United States corroborate the modeled PEC estimates and reductions in TCS concentrations with distance downstream of WWTP discharges. Environmental metabolites, bioaccumulation, biochemical responses including endocrine-related effects, and community level effects are far less well studied for this chemical but are addressed in the discussion. The aquatic risk assessment for TCS should be refined as additional information becomes available. PMID:18260205

Capdevielle, Marie; Van Egmond, Roger; Whelan, Mick; Versteeg, Donald; Hofmann-Kamensky, Matthias; Inauen, Josef; Cunningham, Virginia; Woltering, Daniel



A New Cryptic Species of South American Freshwater Pufferfish of the Genus Colomesus (Tetraodontidae), Based on Both Morphology and DNA Data  

PubMed Central

The Tetraodontidae are an Acantomorpha fish family with circumglobal distribution composed of 189 species grouped in 19 genera, occurring in seas, estuaries, and rivers between the tropical and temperate regions. Of these, the genus Colomesus is confined to South America, with what have been up to now considered only two species. C. asellus is spread over the entire Amazon, Tocantins-Araguaia drainages, and coastal environments from the Amazon mouth to Venezuela, and is the only freshwater puffers on that continent. C. psittacus is found in coastal marine and brackish water environments from Cuba to the northern coast of South America as far south as to Sergipe in Brazil. In the present contribution we used morphological data along with molecular systematics techniques to investigate the phylogeny and phylogeography of the freshwater pufferfishes of the genus Colomesus. The molecular part is based on a cytochrome C oxidase subunit I dataset constructed from both previously published and newly determined sequences, obtained from specimens collected from three distinct localities in South America. Our results from both molecular and morphological approaches enable us to identify and describe a new Colomesus species from the Tocantins River. We also discuss aspects of the historical biogeography and phylogeography of the South American freshwater pufferfishes, suggesting that it could be more recent than previously expected.

Amaral, Cesar R. L.; Brito, Paulo M.; Silva, Dayse A.; Carvalho, Elizeu F.



A new cryptic species of South american freshwater pufferfish of the genus colomesus (tetraodontidae), based on both morphology and DNA data.  


The Tetraodontidae are an Acantomorpha fish family with circumglobal distribution composed of 189 species grouped in 19 genera, occurring in seas, estuaries, and rivers between the tropical and temperate regions. Of these, the genus Colomesus is confined to South America, with what have been up to now considered only two species. C. asellus is spread over the entire Amazon, Tocantins-Araguaia drainages, and coastal environments from the Amazon mouth to Venezuela, and is the only freshwater puffers on that continent. C. psittacus is found in coastal marine and brackish water environments from Cuba to the northern coast of South America as far south as to Sergipe in Brazil. In the present contribution we used morphological data along with molecular systematics techniques to investigate the phylogeny and phylogeography of the freshwater pufferfishes of the genus Colomesus. The molecular part is based on a cytochrome C oxidase subunit I dataset constructed from both previously published and newly determined sequences, obtained from specimens collected from three distinct localities in South America. Our results from both molecular and morphological approaches enable us to identify and describe a new Colomesus species from the Tocantins River. We also discuss aspects of the historical biogeography and phylogeography of the South American freshwater pufferfishes, suggesting that it could be more recent than previously expected. PMID:24040239

Amaral, Cesar R L; Brito, Paulo M; Silva, Dayse A; Carvalho, Elizeu F




EPA Science Inventory

Structure-activity models which were developed to estimate toxicity of chemicals to freshwater fish were tested for use with an estuarine fish (Cyprinodon variegatus) and mysids (Mysidopsis bahia). Significant linear and polunomial relationships that correlated well existed betwe...


Gut content weight and clearance rate for three species of freshwater invertebrates  

SciTech Connect

There is concern for potential error in the accurate estimation of chemical bioaccumulation in benthic organisms due to xenobiotics associated with gut contents (sediments). In this study the benthic macroinvertebrates Hexagenia limbata, Chironomus tentans, and Lumbriculus variegatus were exposed to five sediments from the Lower Fox River/Green Bay area of Wisconsin to determine the percentage of their weight due to gut contents and the rate at which guts were emptied when the animals were held in clean water. Upon removal from the test sediments, inorganic gut contents in H. limbata, C. tentans, and L. variegatus represented approximately 9, 10, and 10% of their whole body dry weights, respectively. Depuration rates were relatively rapid, with mayflies, midges, and oligochaetes losing approximately 75, 90, and 100% of their gut contents during the first 12 h of depuration. This suggests that a 12--24-h holding period in clean water at the conclusion of sediment bioaccumulation tests with the three species should be sufficient to eliminate potential bias in tissue residue concentrations due to gut contents.

Brooke, L.T.; Ankley, G.T.; Call, D.J. [Univ. of Wisconsin, Superior, WI (United States). Lake Superior Research Inst.; Cook, P.M. [Environmental Protection Agency, Duluth, MN (United States). Mid-Continent Ecology Div.



Bioaccumulation of phenol, guaiacol and some chlorophenols by selected freshwater species of leeches.  


In the recent study, the bioaccumulation ability of phenolic substances was determined with field-collected specimens of three leech species, i.e., Erpobdella octoculata (Linnaeus), Theromyzon tessulatum (O. F. M?ller) and Glossiphonia complanata (Linneaus). It was found that the examined leeches bioaccumulated phenol (0.03-27.10 mg/kg), 4-methylphenol (0.09-1.83 mg/kg), chlorophenols (0.03-14.90 mg/kg), guaiacol (0.22-2,941 mg/kg), tetrachloroguaiacol (0.06-1.98 mg/kg), 3-chlorosyringol (0.04-15.28 mg/kg) and chlorocatechols (0.33-23.24 mg/kg) present in the water (0.03-25.23 ?g/L) and in the bottom sediments (0.75-760.5 ?g/kg) of three ecosystems that were characterized by different contamination levels. Analysis of both the external mucous coat of the leeches and the tissue of the dermato-muscular sac showed that substantial quantities of the phenolic compounds may be accumulated in both the mucous (0.03-2,941 mg/kg) and the tissue (0.03-1,189.8 mg/kg). PMID:22476255

Grzelak, Bo?ena; Micha?owicz, Jaromir; Dukowska, Ma?gorzata



Transgenic plants with cyanobacterial genes  

Microsoft Academic Search

Over the years, cyanobacteria have been regarded as ideal model systems for studying fundamental biochemical processes like\\u000a oxygenic photosynthesis and carbon and nitrogen assimilation. Additionally, they have been used as human foods, sources for\\u000a vitamins, proteins, fine chemicals, and bioactive compounds. Aiming to increase plant productivity as well as nutritional\\u000a values, cyanobacterial genes involved in carbon metabolism, fatty acid biosynthesis,

Youn-Il Park; Sang-Bong Choi; Jang R. Liu



UNEP: Freshwater  

NSDL National Science Digital Library

This searchable site, from The United Nations Environment Programme, is a clearinghouse for information about freshwater around the globe. The site provides links to UN reports, background guides on key freshwater issues, and many other resources.

The United Nations Environment Programme (UNEP)


Freshwater Macroinvertebrates.  

ERIC Educational Resources Information Center

|Presents a literature review of freshwater biology particularly freshwater macroinvertebrates and their effect on water pollution, covering publications of 1976-77. A list of 158 references is also presented. (HM)|

Nalepa, T. F.



Freshwater snails of Oman, South Eastern Arabia  

Microsoft Academic Search

A systematic account is given of the extant freshwater snail fauna of Oman, based on recent collections made in Dhofar and in the northern mountainous areas. Also included are certain species found in brackish coastal localities. A total of 8 freshwater species is regarded as belonging to the fauna of normal freshwater; 7 have been found alive (Thiara scabra, Melanoides

D. S. Brown; M. D. Gallagher



Factors influencing tropical island freshwater fishes:Species, status, and management implications in puerto rico [Factores que influencian a los peces tropicales de agua dulce: Especies, estado actual e implicaciones para el manejo en Puerto Rico  

USGS Publications Warehouse

Anthropogenic effects including river regulation, watershed development, contamination, and fish introductions have substantially affected the majority of freshwater habitats in Europe and North America. This pattern of resource development and degradation is widespread in the tropics, and often little is known about the resources before they are lost. This article describes the freshwater resources of Puerto Rico and identifies factors that threaten conservation of native fishes. The fishes found in freshwater habitats of Puerto Rico represent a moderately diverse assemblage composed of 14 orders, 29 families, and 82 species. There are fewer than 10 species of native peripherally-freshwater fish that require a link to marine systems. Introductions of nonindigenous species have greatly expanded fish diversity in freshwater systems, and native estuarine and marine species (18 families) also commonly enter lowland rivers and brackish lagoons. Environmental alterations, including land use and development, stream channelization, pollution, and the impoundment of rivers, combined with nonnative species introductions threaten the health and sustainability of aquatic resources in Puerto Rico. Six principal areas for attention that are important influences on the current and future status of the freshwater fish resources of Puerto Rico are identified and discussed.

Wesley, Neal, J.; Lilyestrom, C. G.; Kwak, T. J.



Study of diatoms/aqueous solution interface. I. Acid-base equilibria and spectroscopic observation of freshwater and marine species  

NASA Astrophysics Data System (ADS)

This work reports on a concerted study of diatom-water interfaces for two marine planktonic ( Thalassiosira weissflogii= TW, Skeletonema costatum= SC) and two freshwater periphytic species ( Achnanthidium minutissimum= AMIN, Navicula minima= NMIN). Proton surface adsorption was measured at 25°C, pH of 3 to 11 and ionic strength of 0.001 to 1.0 M via potentiometric titration using a limited residence time reactor. Electrophoretic mobility of living cells and their frustules was measured as a function of pH and ionic strength. Information on the chemical composition and molecular structure of diatoms surfaces was obtained using FT-IR (in situ attenuated total reflectance) and X-ray Photoelectron Spectroscopy (XPS). The surface area of living cells and their frustules in aqueous solutions was quantified using Small Angle X-ray Scattering Spectroscopy (SAXS). These observations allowed us to identify the nature and to determine the concentration of the major surface functional groups (carboxyl, amine and silanol) responsible for the amphoteric behavior of cell surfaces in aqueous solutions. Taking into account the relative proportion of surface sites inferred from XPS and FT-IR measurements, a surface complexation model of diatom-solution interfaces was generated on the basis of surface titration results. The cell-normalized ratios of the three major surface sites {>COOH}: {>NH 3}: {>SiOH} are 1:1:0.1, 1:10:0, 1:1:0.4 and 1:1:0.3 for TW, SC, AMIN and NMIN, respectively. The total amount of proton/hydroxyl active surface sites for investigated species ranges from 1 (NMIN) to 9 (SC) mmol/g dry weight. Normalization of these site densities to the area of siliceous skeleton yields values between 0.3 (NMIN) and 0.9 mmol/m 2 (SC) which are an order of magnitude higher than corresponding values for organic-free frustules or amorphous silica. This suggests that the amphoteric properties and possibly the affinity for metal adsorption of diatom cultures are essentially controlled by the 3-D organic layers covering the silica frustule.

Gélabert, A.; Pokrovsky, O. S.; Schott, J.; Boudou, A.; Feurtet-Mazel, A.; Mielczarski, J.; Mielczarski, E.; Mesmer-Dudons, N.; Spalla, O.



The semi-aquatic freshwater earthworms of the genus Glyphidrilus Horst, 1889 from Thailand (Oligochaeta, Almidae) with re-descriptions of several species.  


The semi-aquatic freshwater earthworm genus Glyphidrilus Horst, 1889 from Thailand was investigated based on extensive recent collecting. The species in this genus were characterized by their external and internal morphological characters of the location of wings, genital openings, genital organ structures and their locations, as well as the dimensions of body length and number of segments. Several type specimens were compared with both previous and newly collected materials. Ten new species are described from several river systems in Thailand; as Glyphidrilus borealis sp. n., Glyphidrilus chaophraya sp. n., Glyphidrilus chiensis sp. n., Glyphidrilus huailuangensis sp. n., Glyphidrilus kratuensis sp. n., Glyphidrilus quadratus sp. n., Glyphidrilus trangensis sp. n., Glyphidrilus wararamensis sp. n., Glyphidrilus vangthongensis sp. n. and Glyphidrilus vesper sp. n. Each species is endemic to a single river system. All 26 previously described species are re-described, and eight lectotypes have been designated. An identification key and a morphological comparison summary are provided. PMID:23653518

Chanabun, Ratmanee; Sutcharit, Chirasak; Tongkerd, Piyoros; Panha, Somsak



Drivers of cyanobacterial diversity and community composition in mangrove soils in south-east Brazil.  


Cyanobacteria act as primary producers of carbon and nitrogen in nutrient-poor ecosystems such as mangroves. This important group of microorganisms plays a critical role in sustaining the productivity of mangrove ecosystems, but the structure and function of cyanobacteria assemblages can be perturbed by anthropogenic influences. The aim of this work was to assess the community structure and ecological drivers that influence the cyanobacterial community harboured in two Brazilian mangrove soils, and examine the long-term effects of oil contamination on these keystone species. Community fingerprinting results showed that, although cyanobacterial communities are distinct between the two mangroves, the structure and diversity of the assemblages exhibit similar responses to environmental gradients. In each ecosystem, cyanobacteria occupying near-shore areas were similar in composition, indicating importance of marine influences for structuring the community. Analysis of 16S rRNA sequences revealed the presence of diverse cyanobacterial communities in mangrove sediments, with clear differences among mangrove habitats along a transect from shore to forest. While near-shore sites in both mangroves were mainly occupied by Prochlorococcus and Synechococcus genera, sequences retrieved from other mangrove niches were mainly affiliated with uncultured cyanobacterial 16S rRNA. The most intriguing finding was the large number of potentially novel cyanobacteria 16S rRNA sequences obtained from a previously oil-contaminated site. The abundance of cyanobacterial 16S rRNA sequences observed in sites with a history of oil contamination was significantly lower than in the unimpacted areas. This study emphasized the role of environmental drivers in determining the structure of cyanobacterial communities in mangrove soils, and suggests that anthropogenic impacts may also act as ecological filters that select cyanobacterial taxa. These results are an important contribution to our understanding of the composition and relative abundance of previously poorly described cyanobacterial assemblages in mangrove ecosystems. PMID:22816485

Rigonato, Janaina; Kent, Angela D; Alvarenga, Danillo O; Andreote, Fernando D; Beirigo, Raphael M; Vidal-Torrado, Pablo; Fiore, Marli F



Origins of a cyanobacterial 6-phosphogluconate dehydrogenase in plastid-lacking eukaryotes  

PubMed Central

Background Plastids have inherited their own genomes from a single cyanobacterial ancestor, but the majority of cyanobacterial genes, once retained in the ancestral plastid genome, have been lost or transferred into the eukaryotic host nuclear genome via endosymbiotic gene transfer. Although previous studies showed that cyanobacterial gnd genes, which encode 6-phosphogluconate dehydrogenase, are present in several plastid-lacking protists as well as primary and secondary plastid-containing phototrophic eukaryotes, the evolutionary paths of these genes remain elusive. Results Here we show an extended phylogenetic analysis including novel gnd gene sequences from Excavata and Glaucophyta. Our analysis demonstrated the patchy distribution of the excavate genes in the gnd gene phylogeny. The Diplonema gene was related to cytosol-type genes in red algae and Opisthokonta, while heterolobosean genes occupied basal phylogenetic positions with plastid-type red algal genes within the monophyletic eukaryotic group that is sister to cyanobacterial genes. Statistical tests based on exhaustive maximum likelihood analyses strongly rejected that heterolobosean gnd genes were derived from a secondary plastid of green lineage. In addition, the cyanobacterial gnd genes from phototrophic and phagotrophic species in Euglenida were robustly monophyletic with Stramenopiles, and this monophyletic clade was moderately separated from those of red algae. These data suggest that these secondary phototrophic groups might have acquired the cyanobacterial genes independently of secondary endosymbioses. Conclusion We propose an evolutionary scenario in which plastid-lacking Excavata acquired cyanobacterial gnd genes via eukaryote-to-eukaryote lateral gene transfer or primary endosymbiotic gene transfer early in eukaryotic evolution, and then lost either their pre-existing or cyanobacterial gene.



Alternative isoleucine synthesis pathway in cyanobacterial species.  


Cyanothece sp. ATCC 51142 is an aerobic N(2)-fixing and hydrogen-producing cyanobacterium. Isotopomer analysis of its amino acids revealed an identical labelling profile for leucine and isoleucine when Cyanothece 51142 was grown mixotrophically using 2-(13)C-labelled glycerol as the main carbon source. This indicated that Cyanothece 51142 employs the atypical alternative citramalate pathway for isoleucine synthesis, with pyruvate and acetyl-CoA as precursors. Utilization of the citramalate pathway was confirmed by an enzyme assay and LC-MS/MS analysis. Furthermore, the genome sequence of Cyanothece 51142 shows that the gene encoding the key enzyme (threonine ammonia-lyase) in the normal isoleucine pathway is missing. Instead, the cce_0248 gene in Cyanothece 51142 exhibits 53 % identity to the gene encoding citramalate synthase (CimA, GSU1798) from Geobacter sulfurreducens. Reverse-transcription PCR indicated that the cce_0248 gene is expressed and its transcriptional level is lower in medium with isoleucine than in isoleucine-free medium. Additionally, a blast search for citramalate synthase and threonine ammonia-lyase implies that this alternative isoleucine synthesis pathway may be present in other cyanobacteria, such as Cyanothece and Synechococcus. This suggests that the pathway is more widespread than originally thought, as previous identifications of the citramalate pathway are limited to mostly anaerobic bacteria or archaea. Furthermore, this discovery opens the possibility that such autrotrophic micro-organisms may be engineered for robust butanol and propanol production from 2-ketobutyrate, which is an intermediate in the isoleucine biosynthesis pathway. PMID:19875435

Wu, Bing; Zhang, Baichen; Feng, Xueyang; Rubens, Jacob R; Huang, Rick; Hicks, Leslie M; Pakrasi, Himadri B; Tang, Yinjie J



New records or species of Dictyochaeta, Endophragmiella and Ramichloridium from submerged wood in Hong Kong freshwater streams  

Microsoft Academic Search

Endophragmiella triseptata sp. nov. and Ramichloridium lignicola sp. nov. are described from submerged wood collected from freshwater habitats from Hong Kong. A collection of Dictyochaeta subfuscospora presenting some unusual features is reported, while Dictyochaeta vittata is a new record for Hong Kong.

Clement K. M. Tsui; T. K. Goh; Kevin D. Hyde; I. John Hodgkiss



Cyanobacterial biofertilizers in rice agriculture  

Microsoft Academic Search

Floodwater and the surface of soil provide the sites for aerobic phototrophic nitrogen (N) fixation by free-living cyanobacteria\\u000a and theAzolla-Anabaena symbiotic N2-fixing complex. Free-living cyanobacteria, the majority of which are heterocystous and nitrogen fixing, contribute an average\\u000a of 20–30 kg N ha-1, whereas the value is up to 600 kg ha-1 for theAzollaAnabaena system (the most beneficial cyanobacterial symbiosis from

A. Vaishampayan; R. P. Sinha; D.-P. Hader; T. Dey; A. K. Gupta; U. Bhan; A. L. Rao



Cyanobacterial blooms: statistical models describing risk factors for national-scale lake assessment and lake management.  


Cyanobacterial toxins constitute one of the most high risk categories of waterborne toxic biological substances. For this reason there is a clear need to know which freshwater environments are most susceptible to the development of large populations of cyanobacteria. Phytoplankton data from 134 UK lakes were used to develop a series of Generalised Additive Models and Generalised Additive Mixed Models to describe which kinds of lakes may be susceptible to cyanobacterial blooms using widely available explanatory variables. Models were developed for log cyanobacterial biovolume. Water colour and alkalinity are significant explanatory variables and retention time and TP borderline significant (R2-adj=21.9%). Surprisingly, the models developed reveal that nutrient concentrations are not the primary explanatory variable; water colour and alkalinity were more important. However, given suitable environments (low colour, neutral-alkaline waters), cyanobacteria do increase with both increasing retention time and increasing TP concentrations, supporting the observations that cyanobacteria are one of the most visible symptoms of eutrophication, particularly in warm, dry summers. The models can contribute to the assessment of risks to public health, at a regional to national level, helping target lake monitoring and management more cost-effectively at those lakes at the highest risk of breaching World Health Organisation guideline levels for cyanobacteria in recreational waters. The models also inform restoration options available for reducing cyanobacterial blooms, indicating that, in the highest risk lakes (alkaline, low colour lakes), risks can generally be lessened through management aimed at reducing nutrient loads and increasing flushing during summer. PMID:21975001

Carvalho, Laurence; Miller nee Ferguson, Claire A; Scott, E Marian; Codd, Geoffrey A; Davies, P Sian; Tyler, Andrew N



Assessment of the Species Composition, Densities, and Distribution of Native Freshwater Mussels along the Benton County Shoreline of the Hanford Reach, Columbia River, 2004  

SciTech Connect

The Hanford Reach of the Columbia River is the last unimpounded section of the river and contains substrate characteristics (cobble, gravel, sand/silt) suitable for many of the native freshwater mussels known to exist in the Pacific Northwest. Information concerning the native mussel species composition, densities, and distributions in the mainstem of the Columbia River is limited. Under funding from the U.S. Department of Energy Richland Operations Office (DOE-RL), Pacific Northwest National Laboratory conducted an assessment of the near-shore habitat on the Hanford Reach. Surveys conducted in 2004 as part of the Ecological Monitoring and Compliance project documented several species of native mussels inhabiting the near-shore habitat of the Hanford Reach. Findings reported here may be useful to resource biologists, ecologists, and DOE-RL to determine possible negative impacts to native mussels from ongoing near-shore remediation activities associated with Hanford Site cleanup. The objective of this study was to provide an initial assessment of the species composition, densities, and distribution of the freshwater mussels (Margaritiferidae and Unionidae families) that exist in the Hanford Reach. Researchers observed and measured 201 live native mussel specimens. Mussel density estimated from these surveys is summarized in this report with respect to near-shore habitat characteristics including substrate size, substrate embeddedness, relative abundance of aquatic vegetation, and large-scale geomorphic/hydrologic characteristics of the Hanford Reach.

Mueller, Robert P.; Tiller, Brett L.; Bleich, Matthew D.; Turner, Gerald; Welch, Ian D.



Intrahost distribution and transmission of a new species of cyclopoid copepod endosymbiotic to a freshwater snail, Pomacea canaliculata (Caenogastropoda, Ampullariidae), from Argentina.  


A new species of cyclopoid copepod, Ozmana huarpium, is described as a symbiont to Pomacea canaliculata (Lamarck 1822) (Caenogastropoda, Ampullariidae). Rather large numbers (about one hundred copepods per snail) were found, although there was no evidence of harm to the host. To our knowledge, O. haemophila (symbiont to P. maculata), and the currently described species, O. huarpium, are the only copepod species ever recorded as endosymbionts to freshwater invertebrates. While O. haemophila is restricted to the haemocoel of its host, O. huarpium predominate in the penis sheath, the ctenidium and the mantle cavity, figuring in these pallial organs 63-65% of total mature forms. The sex ratio of the symbiont is skewed to the female side in these organs, specially in male hosts. The hypothesis that a special female tropism for the male host's pallial organs might ensure interindividual transmission of the symbiont was tested, with indications that the symbiont is mainly transmitted during copulation. PMID:15462567

Gamarra-Luques, C D; Vega, I A; Koch, E; Castro-Vazquez, A



The influence of freshwater inflows on spawning success and early growth of an estuarine resident fish species, Acanthopagrus butcheri.  


The influence of freshwater inflows and salinity on spawning success of black bream Acanthopagrus butcheri (Sparidae) was investigated over 2 years in a small estuary on the east coast of Tasmania, Australia. The individual spawning seasons experienced quite different freshwater inflows; 2004-2005 was characterized by low flows throughout the season whereas during 2005-2006 there were three relatively large discharge events in the first part of the season. Macroscopic gonad staging of adults was used to define the spawning season and daily increment analysis of otoliths from recently settled recruits was used to backcalculate spawning dates. Gonad staging indicated that adults were in spawning condition over a 3 to 4 month period during spring and summer. The timing and duration of successful spawning, however, differed markedly between years and was linked to the timing of freshwater inflows and salinity conditions, with successful spawning occurring during periods of low freshwater discharge and when salinities in the upper estuary were above c. 15. Growth rates of the recently settled recruits did not differ between years, nor did the timing of spawning within the season influence growth rates. While the latter finding was unexpected, especially given within season temperature variability, these results imply that by the onset of winter earlier spawned fish would be larger than later spawned individuals, potentially conferring advantages for survival and competition for food. Climate change predictions for eastern Tasmania indicate a decrease in river flows in spring and an increase during summer, potentially increasing environmental variability between and within years, with implications for spawning success and subsequent recruitment. PMID:21539557

Sakabe, R; Lyle, J M; Crawford, C M



Integrative taxonomy of a new species of planarian from the Lake Ohrid basin, including an analysis of biogeographical patterns in freshwater triclads from the Ohrid region (Platyhelminthes, Tricladida, Dugesiidae)  

PubMed Central

Abstract A new species of the genus Dugesia is described from the Lake Ohrid region in the western part of the Balkan Peninsula, forming the first fully documented species description for this genus in the Ohrid area. The morphological species delimitation is supported by complementary molecular, karyological, and cytogenetic data available from the literature. Therefore, species delineation is based on a truly integrative approach. Further, a short account on the degree of freshwater planarian endemicity in the Ohrid region is provided.

Stocchino, Giacinta Angela; Sluys, Ronald; Deri, Paolo; Manconi, Renata



Allergenic (sensitization, skin and eye irritation) effects of freshwater cyanobacteria--experimental evidence.  


Many studies have been published on the human health effects of cyanobacterial toxicity. As a public health concern, we have to mention that the development of contact dermatitis, asthmalike symptoms, and symptoms resembling hay fever during bathing in cyanobacterial blooms have been also described. Microcystis aeruginosa, Anabaena flos-aquae, Aphanizomenon flos-aquae, and Cylindrospermopsis raciborskii are the most common species found in Hungarian freshwaters. A sensitization test on albino guinea pigs, and intradermal reactivity, and occular irritation test on albino rabbits were carried out with freeze-dried algal suspension in physiological salt solution. The sensitivity of guinea pigs is similar to that of humans. Microcystis, Anabaena, Cylindrospermopsis, and Aphanizomenon bloom and strain samples were examined in sensitization and irritation tests and no correlation was found between the toxin content and the allergenic character. The most toxic one (Microcystis aeruginosa) was not the most allergenic sample, but the nontoxic Aphanizomenon was the most allergenic one. The axenic strains were not allergenic at all. The pure microcystin LR was only slightly allergenic even in high concentration (1.5 mg/ml). Water and lipid soluble fractions were obtained by water and chloroform extraction of lyophilized algal suspensions. The chloroform fraction was bound on C18 cartridges and eluted by methanol in nine fractions. Only one of the lipid soluble fractions was skin irritative whereas the strongest irritative effect was shown by the water soluble fraction. PMID:11769249

Torokne, A; Palovics, A; Bankine, M



Cyanobacterial lipopolysaccharides and human health - a review  

PubMed Central

Cyanobacterial lipopolysaccharide/s (LPS) are frequently cited in the cyanobacteria literature as toxins responsible for a variety of heath effects in humans, from skin rashes to gastrointestinal, respiratory and allergic reactions. The attribution of toxic properties to cyanobacterial LPS dates from the 1970s, when it was thought that lipid A, the toxic moiety of LPS, was structurally and functionally conserved across all Gram-negative bacteria. However, more recent research has shown that this is not the case, and lipid A structures are now known to be very different, expressing properties ranging from LPS agonists, through weak endotoxicity to LPS antagonists. Although cyanobacterial LPS is widely cited as a putative toxin, most of the small number of formal research reports describe cyanobacterial LPS as weakly toxic compared to LPS from the Enterobacteriaceae. We systematically reviewed the literature on cyanobacterial LPS, and also examined the much lager body of literature relating to heterotrophic bacterial LPS and the atypical lipid A structures of some photosynthetic bacteria. While the literature on the biological activity of heterotrophic bacterial LPS is overwhelmingly large and therefore difficult to review for the purposes of exclusion, we were unable to find a convincing body of evidence to suggest that heterotrophic bacterial LPS, in the absence of other virulence factors, is responsible for acute gastrointestinal, dermatological or allergic reactions via natural exposure routes in humans. There is a danger that initial speculation about cyanobacterial LPS may evolve into orthodoxy without basis in research findings. No cyanobacterial lipid A structures have been described and published to date, so a recommendation is made that cyanobacteriologists should not continue to attribute such a diverse range of clinical symptoms to cyanobacterial LPS without research confirmation.

Stewart, Ian; Schluter, Philip J; Shaw, Glen R



Computational prediction of cAMP receptor protein (CRP) binding sites in cyanobacterial genomes  

PubMed Central

Background Cyclic AMP receptor protein (CRP), also known as catabolite gene activator protein (CAP), is an important transcriptional regulator widely distributed in many bacteria. The biological processes under the regulation of CRP are highly diverse among different groups of bacterial species. Elucidation of CRP regulons in cyanobacteria will further our understanding of the physiology and ecology of this important group of microorganisms. Previously, CRP has been experimentally studied in only two cyanobacterial strains: Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120; therefore, a systematic genome-scale study of the potential CRP target genes and binding sites in cyanobacterial genomes is urgently needed. Results We have predicted and analyzed the CRP binding sites and regulons in 12 sequenced cyanobacterial genomes using a highly effective cis-regulatory binding site scanning algorithm. Our results show that cyanobacterial CRP binding sites are very similar to those in E. coli; however, the regulons are very different from that of E. coli. Furthermore, CRP regulons in different cyanobacterial species/ecotypes are also highly diversified, ranging from photosynthesis, carbon fixation and nitrogen assimilation, to chemotaxis and signal transduction. In addition, our prediction indicates that crp genes in modern cyanobacteria are likely inherited from a common ancestral gene in their last common ancestor, and have adapted various cellular functions in different environments, while some cyanobacteria lost their crp genes as well as CRP binding sites during the course of evolution. Conclusion The CRP regulons in cyanobacteria are highly diversified, probably as a result of divergent evolution to adapt to various ecological niches. Cyanobacterial CRPs may function as lineage-specific regulators participating in various cellular processes, and are important in some lineages. However, they are dispensable in some other lineages. The loss of CRPs in these species leads to the rapid loss of their binding sites in the genomes.

Xu, Minli; Su, Zhengchang



Comparative analysis of cyanobacterial superoxide dismutases to discriminate canonical forms  

PubMed Central

Background Superoxide dismutases (SOD) are ubiquitous metalloenzymes that catalyze the disproportion of superoxide to peroxide and molecular oxygen through alternate oxidation and reduction of their metal ions. In general, SODs are classified into four forms by their catalytic metals namely; FeSOD, MnSOD, Cu/ZnSOD and NiSOD. In addition, a cambialistic form that uses Fe/Mn in its active site also exists. Cyanobacteria, the oxygen evolving photosynthetic prokaryotes, produce reactive oxygen species that can damage cellular components leading to cell death. Thus, the co-evolution of an antioxidant system was necessary for the survival of photosynthetic organisms with SOD as the initial enzyme evolved to alleviate the toxic effect. Cyanobacteria represent the first oxygenic photoautotrophs and their SOD sequences available in the databases lack clear annotation. Hence, the present study focuses on structure and sequence pattern of subsets of cyanobacterial superoxide dismutases. Result The sequence conservation and structural analysis of Fe (Thermosynechococcus elongatus BP1) and MnSOD (Anabaena sp. PCC7120) reveal the sharing of N and C terminal domains. At the C terminal domain, the metal binding motif in cyanoprokaryotes is DVWEHAYY while it is D-X-[WF]-E-H-[STA]-[FY]-[FY] in other pro- and eukaryotes. The cyanobacterial FeSOD differs from MnSOD at least in three ways viz. (i) FeSOD has a metal specific signature F184X3A188Q189.......T280......F/Y303 while, in Mn it is R184X3G188G189......G280......W303, (ii) aspartate ligand forms a hydrogen bond from the active site with the outer sphere residue of W243 in Fe where as it is Q262 in MnSOD; and (iii) two unique lysine residues at positions 201 and 255 with a photosynthetic role, found only in FeSOD. Further, most of the cyanobacterial Mn metalloforms have a specific transmembrane hydrophobic pocket that distinguishes FeSOD from Mn isoform. Cyanobacterial Cu/ZnSOD has a copper domain and two different signatures G-F-H-[ILV]-H-x-[NGT]-[GPDA]-[SQK]-C and G-[GA]-G-G-[AEG]-R-[FIL]-[AG]-C-G, while Ni isoform has an nickel containing SOD domain containing a Ni-hook HCDGPCVYDPA. Conclusion The present analysis unravels the ambiguity among cyanobacterial SOD isoforms. NiSOD is the only SOD found in lower forms; whereas, Fe and Mn occupy the higher orders of cyanobacteria. In conclusion, cyanobacteria harbor either Ni alone or a combination of Fe and Ni or Fe and Mn as their catalytic active metal while Cu/Zn is rare.

Priya, Balakrishnan; Premanandh, Jagadeesan; Dhanalakshmi, Raman T; Seethalakshmi, Thangaraj; Uma, Lakshmanan; Prabaharan, Dharmar; Subramanian, Gopalakrishnan



Can cyanobacterial biomass applied to soil affect survival and reproduction of springtail Folsomia candida?  


Biomass of cyanobacterial water blooms including cyanobacterial toxins may enter soils, for example, when harvested water bloom is directly applied as an organic fertilizer or when water with massive cyanobacterial biomass is used for irrigation. In spite of this, no information is available about the potential effects on soil arthropods. The objective of this pilot study was to evaluate the effects of water bloom biomass sampled in five different fresh water lakes on the soil dwelling arthropod, springtail Folsomia candida (Collembola). These samples contained different dominant species of cyanobacteria and varied significantly in microcystin content (21-3662 ?g/g dw biomass). No adverse effects on survival or reproduction were observed for any tested sample at concentration up to 4 g dw biomass/kg dw soil. Despite the known hazardous properties of water blooms in aquatic ecosystems, our pilot results suggest that cyanobacterial biomass might have no significant impact on arthropods in soil. It remains a question, if this is due to low bioavailability of cyanobacterial toxins in soil. PMID:21176962

Lána, Jan; Hofman, Jakub; Bláha, Lud?k



Factors and processes shaping the population structure and distribution of genetic variation across the species range of the freshwater snail radix balthica (Pulmonata, Basommatophora)  

PubMed Central

Background Factors and processes shaping the population structure and spatial distribution of genetic diversity across a species' distribution range are important in determining the range limits. We comprehensively analysed the influence of recurrent and historic factors and processes on the population genetic structure, mating system and the distribution of genetic variability of the pulmonate freshwater snail Radix balthica. This analysis was based on microsatellite variation and mitochondrial haplotypes using Generalised Linear Statistical Modelling in a Model Selection framework. Results Populations of R. balthica were found throughout North-Western Europe with range margins marked either by dispersal barriers or the presence of other Radix taxa. Overall, the population structure was characterised by distance independent passive dispersal mainly along a Southwest-Northeast axis, the absence of isolation-by-distance together with rather isolated and genetically depauperated populations compared to the variation present in the entire species due to strong local drift. A recent, climate driven range expansion explained most of the variance in genetic variation, reducing at least temporarily the genetic variability in this area. Other factors such as geographic marginality and dispersal barriers play only a minor role. Conclusions To our knowledge, such a population structure has rarely been reported before. It might nevertheless be typical for passively dispersed, patchily distributed taxa (e.g. freshwater invertebrates). The strong local drift implied in such a structure is expected to erode genetic variation at both neutral and coding loci and thus probably diminish evolutionary potential. This study shows that the analysis of multiple factors is crucial for the inference of the processes shaping the distribution of genetic variation throughout species ranges.



Comparative characterization of Na+ transport in Cyprinodon variegatus variegatus and Cyprinodon variegatus hubbsi: a model species complex for studying teleost invasion of freshwater.  


The euryhaline fish Cyprinodon variegatus variegatus is capable of tolerating ambient salinities ranging from 0.3 to 160 PSU, but is incapable of long-term survival in freshwater (<2 mmol l(-1) Na(+)). A population isolated in several freshwater (0.4-1 mmol l(-1) Na(+)) lakes in central Florida is now designated as a subspecies (Cyprinodon variegatus hubbsi). We conducted a comparative study of Na(+) transport kinetics in these two populations when acclimated to different ambient Na(+) concentrations. Results reveal that the two subspecies have qualitatively similar low affinity Na(+) uptake kinetics (K(m)=7000-38,000 ?mol l(-1)) when acclimated to 2 or 7 mmol l(-1) Na(+), but C. v. hubbsi switches to a high affinity system (K(m)=100-140 ?mol l(-1)) in low-Na(+) freshwater (?1 mmol l(-1) Na(+)). Inhibitor experiments indicate that Na(+) uptake in both subspecies is EIPA-sensitive, but sensitivity decreases with increasing external Na(+). EIPA induced a 95% inhibition of Na(+) influx in C. v. hubbsi acclimated to 0.1 mmol l(-1) Na(+), suggesting that this subspecies is utilizing a Na(+)/H(+) exchanger to take up Na(+) in low-Na(+) environments despite theoretical thermodynamic constraints. Na(+) uptake in C. v. hubbsi acclimated to 0.1 mmol l(-1) Na(+) is phenamil-sensitive but not bafilomycin-sensitive, leading to uncertainty about whether this subspecies also utilizes Na(+) channels for Na(+) uptake. Experiments with both subspecies acclimated to 7 mmol l(-1) Na(+) also indicate that a Cl(-)-dependent Na(+) uptake pathway is present. This pathway is not metolazone-sensitive (NCC inhibitor) in either species but is bumetanide-sensitive in C. v. variegatus but not C. v. hubbsi. This suggests that an apical NKCC is increasingly involved with Na(+) uptake for this subspecies as external Na(+) increases. Finally, characterization of mitochondria-rich cell (MRC) size and density in fish acclimated to different ambient Na(+) concentrations revealed significant increases in the number and size of emergent MRCs with decreasing ambient Na(+). A linear relationship between the fractional area of emergent MRCs and Na(+) uptake rate was observed for both subspecies. However, C. v. variegatus have lower Na(+) uptake rates at a given MRC fractional area compared with C. v. hubbsi, indicating that the enhanced Na(+) uptake by C. v. hubbsi at low ambient Na(+) concentrations is not strictly a result of increased MRC fractional area, and other variables, such as differential expression of proteins involved in Na(+) uptake, must provide C. v. hubbsi with the ability to osmoregulate in dilute freshwater. PMID:22399666

Brix, Kevin V; Grosell, Martin



Cyanobacterial composition of microbial mats from an Australian thermal spring: a polyphasic evaluation.  


Cyanobacterial composition of microbial mats from an alkaline thermal spring issuing at 43-71 degrees C from tropical north-eastern Australia are described using a polyphasic approach. Eight genera and 10 species from three cyanobacterial orders were identified based on morphological characters. These represented taxa previously known as thermophilic from other continents. Ultrastructural analysis of the tower mats revealed two filamentous morphotypes contributed the majority of the biomass. Both types had ultrastructural characteristics of the family Pseudanabaenaceae. DNA extracts were made from sections of the tentaculiform towers and the microbial community analysed by 16S cyanobacteria-specific PCR and denaturing-gradient gel electrophoresis. Five significant bands were identified and sequenced. Two bands clustered closely with Oscillatoria amphigranulata isolated from New Zealand hot springs; one unique phylotype had only moderate similarity to a range of Leptolyngbya species; and one phylotype was closely related to a number of Geitlerinema species. Generally the approaches yielded complementary information, however the results suggest that species designation based on morphological and ultrastructural criteria alone often fails to recognize their true phylogenetic position. Conversely some molecular techniques may fail to detect rare taxa suggesting that the widest possible suite of techniques be applied when conducting analyses of cyanobacterial diversity of natural populations. This is the first polyphasic evaluation of thermophilic cyanobacterial communities from the Australian continent. PMID:18081588

McGregor, Glenn B; Rasmussen, J Paul



Enzymatic Pathway for the Bacterial Degradation of the Cyanobacterial Cyclic Peptide Toxin Microcystin LR  

Microsoft Academic Search

An isolated bacterium, identified as a new Sphingomonas species, was demonstrated to contain a novel enzymatic pathway which acted on microcystin LR, the most common cyanobacterial cyclic peptide toxin. Degradation of microcystin LR was mediated by at least three intracellular hydrolytic enzymes. The use of classicproteaseinhibitorsallowed(i)theclassificationoftheseenzymesintogeneralproteasefamiliesand(ii) the in vitro accumulation of otherwise transient microcystin LR degradation products. The initial site




Two new nematode species, Paragendria papuanensis sp. n. (Seuratoidea) and Rhabdochona papuanensis sp. n. (Thelazioidea), from freshwater fishes in Papua New Guinea.  


Two new nematode species, Paragendria papuanensis sp. n. (Quimperiidae) and Rhabdochona papuanensis sp. n. (Rhabdochonidae), are described from the intestine of freshwater fishes Glossamia giellerupi (Weber et Beaufort) (Apogonidae) and Melanotaenia affinis (Weber) (Melanotaeniidae), respectively, from the Sogeram River (Ramu River basin), Madang Province, northern Papua New Guinea. The former species is characterized mainly by the absence of oesophageal teeth, the presence of conspicuously inflated papillae of the last two subventral pairs, a gubernaculum, spicules 69-75 microm long, eggs measuring 57-66 x 39-45 microm, and by a small body (male and female 3.2-3.7 and 5.8 mm long, respectively). Paragendria is considered a valid genus, to which P. aori (Khan et Yaseen, 1969) comb. n., P. guptai (Gupta et Masoodi, 2000) comb. n., P. hanumanthai (Gupta et Jaiswal, 1988) comb. n. and P. vermae (Gupta et Masoodi, 2000) comb. n. are newly transferred. Rhabdochona papuanensis differs from all congeners mainly in having hammer-shaped deirids and from individual species also in other characters. Both findings represent the first records of species of Paragendria and Rhabdochona from the Australian zoogeographical region and the first records of the representatives of these genera from fishes of the families Apogonidae and Melanotaeniidae, respectively. PMID:18666416

Moravec, Frantisek; Ríha, Milan; Kuchta, Roman



Potential role of cholinesterases in the invasive capacity of the freshwater bivalve, Anodonta woodiana (Bivalvia: Unionacea): a comparative study with the indigenous species of the genus, Anodonta sp.  


To address the potential role of cholinesterase enzymes in the invasive capacity of species, the present study investigated ChE activity in the invasive freshwater bivalve Anodonta woodiana (Lea, 1834) comparing it with that of the indigenous species, Anodonta sp. (Linnaeus, 1758). The invasive capacity of pests has often been linked to their ecological plasticity and high intrinsic genetic variability; however the role played by molecular and cellular mechanisms, generally known as an organism's response to pollution, is unclear. Different substrates and selective ChE enzyme inhibitors were investigated in digestive gland, foot, gonad, adductor muscle and gill tissues while sensitivity to four organophosphate (OP) insecticides was investigated in vitro only in adductor muscle. The invasive species (A. woodiana) showed significantly greater (at least one order of magnitude) ChE activity than the endemic species (Anodonta sp.) (p<0.05) using acetylthiocholine (ASCh) as substrate and the activity was more widely distributed in tissues involved in movement (adductor muscle and foot), respiration, feeding (gills) and reproduction (gonads). Moreover, only the invasive species, A. woodiana, showed detectable ChE (vs. ASCh) activity in gill tissue. No substrate specificity was observed in any tissue of either species as already described for other bivalve species. ChE activity was not inhibited by Iso-OMPA but showed high sensitivity to BW248c51 and eserine. Both species showed moderate to low sensitivities in vitro to OP insecticides in the range 10(-7)-10(-2) M. Calculated IC(50) for fenitrothion and chlorpyrifos was in the range 10(-6)-10(-3) M in muscle of A. woodiana while a higher inhibition was observed for fenitrothion (10(-7) M) and lower for chlorpyrifos (10(-2) M) in the indigenous species Anodonta sp. Similar IC(50) of 10(-5)-10(-6) M were observed for DFP and azamethiphos in both species. The hypotheses of other authors that acetylcholinesterase (AChE) is involved in the control of many essential functions, such as frontal ciliary activity of gill epithelium, temperature resistance, ciliary activity for transport of suspended particulate, valve opening and embryo development, suggest that the high catalytic efficiency of the invasive species may endow it with a competitive advantage over the endemic species. In view of the peculiar reproductive strategy of these mussels, higher ChE vs. ASCh activity in gonads of the invasive species could also favour glochidium production and embryo development under a wider range of environmental conditions. PMID:17324630

Corsi, Ilaria; Pastore, Angela Maria; Lodde, Antonella; Palmerini, Emanuela; Castagnolo, Lucio; Focardi, Silvano



Two new species of the genus Goezia, G. brasiliensis sp. n. and G. brevicaeca sp. n. (Nematoda: Anisakidae), from freshwater fishes in Brazil.  


Examination of freshwater fishes from the Paraná River in southern Brazil during March 1992, revealed the presence of two new, previously undescribed species of the genus Goezia: G. brasiliensis sp. n. is described from the stomach of Brycon hilarii (family Characidae) (type host) and the intestine of Pseudoplatystoma coruscans (Pimelodidae) and it is characterized mainly by the length (0.802 mm) of spicules, number and arrangement of male caudal papillae (10 pairs of preanals and 4 pairs of postanals) and body measurements (male 11 mm, female 10-16 mm); the main characteristics of G. brevicaeca sp. n., described from the stomach of Brycon hilarii, are a short anterior intestinal caecum reaching anteriorly only to the posterior end of oesophagus, comparatively short spicules (0.367 mm), number of male caudal papillae (20 pairs of preanals and 4 pairs of post-anals) and an elongate, rather long body (male 17 mm, female 23 mm). PMID:7883259

Moravec, F; Kohn, A; Fernandes, B M



A freshwater species wintering in a brackish environment: Habitat selection and diet of Slavonian grebes in the southern Baltic Sea  

NASA Astrophysics Data System (ADS)

After the breeding season, Slavonian grebes ( Podiceps auritus) leave their freshwater breeding habitats and migrate to wintering grounds in marine or brackish waters. The most important wintering area in northwestern Europe is located in the southern Baltic Sea, with the largest concentrations in the offshore area of the Pommeranian Bight. Analysis of ship-based surveys revealed that the habitat selection of Slavonian grebes in this brackish area is significantly influenced by water depth and bottom sediment type. The grebes prefer shallow waters of 4-14 m depth and occur only over sandy sediments. While the diving depths of endothermic animals is limited due to energetic constraints and thermoregulation, sediment type is regarded to be a proxy for food choice. The diet of Slavonian grebes in the Pomeranian Bight consists mainly of demersal gobies (Gobiidae) that frequently occur over sandy bottom substrates.

Sonntag, Nicole; Garthe, Stefan; Adler, Sven



Identification of a Diagnostic Marker To Detect Freshwater Cyanophages of Filamentous Cyanobacteria  

Microsoft Academic Search

Cyanophages are viruses that infect the cyanobacteria, globally important photosynthetic microorganisms. Cyanophages are considered significant components of microbial communities, playing major roles in influ- encing host community diversity and primary productivity, terminating cyanobacterial water blooms, and influencing biogeochemical cycles. Cyanophages are ubiquitous in both marine and freshwater systems; however, the majority of molecular research has been biased toward the study

Andrea C. Baker; Victoria J. Goddard; Joanne Davy; Declan C. Schroeder; David G. Adams; William H. Wilson



Absence of sterols constrains carbon transfer between cyanobacteria and a freshwater herbivore (Daphnia galeata)  

Microsoft Academic Search

A key process in freshwater plankton food webs is the regulation of the efficiency of energy and material transfer. Cyanobacterial carbon (C) in particular is transferred very inefficiently to herbivorous zooplank- ton, which leads to a decoupling of primary and secondary production and the accumulation of cyanobact- erial biomass, which is associated with reduced recreational quality of water bodies and

Eric von Elert; Dominik Martin-Creuzburg; Jean R. Le Coz



Freshwater Protected Areas: Strategies for Conservation  

Microsoft Academic Search

Freshwater species and habitats are among the most threatened in the world. One way in which this growing conservation concern can be addressed is the creation of freshwater protected areas. Here, we present three strategies for freshwater protected-area design and management: whole-catchment management, natu- ral-flow maintenance, and exclusion of non-native species. These strategies are based on the three primary threats

D. L. Saunders; J. J. Meeuwig; A. C. J. Vincent



Pre-Columbian use of freshwater fish in the Santa Maria Biogeographical Province, Panama  

Microsoft Academic Search

Freshwater fish faunas on the Isthmus of Panama are less diverse than those of the great South American river basins. Few freshwater species attain a large size (>500g). The largest species regularly caught today in the lower freshwater sections of many Panamanian rivers are of marine origin. Freshwater fish species diversity and biomass decline rapidly with altitude particularly on the

Richard Cooke; Máximo Jiménez



Differences in the effects of salinity on larval growth and developmental programs of a freshwater and a euryhaline mosquito species (Insecta: Diptera, Culicidae).  


The effects of salinity on growth and development of the euryhaline Ochlerotatus taeniorhynchus and the freshwater Aedes aegypti are compared. O. taeniorhynchus grow larger, and have greater intrinsic growth rates, than A. aegypti. Females of each species attain greater mass, take longer to develop, and have greater growth rates than do males. In O. taeniorhynchus, pupal mass, larval stage duration and growth rates (dry mass) increase with salinity, whereas growth rates (wet mass) remain constant across salinities, reflecting a decrease in percent body water. The pupal mass (wet or dry) of O. taeniorhynchus is determined primarily by effects of salinity on the rate of assimilation of dry mass, because the latter contributes very strongly to final pupal mass in both species. In contrast, the duration of A. aegypti larval stage follows a upsilon-shaped curve, with most rapid development at intermediate salinities. Growth rates of A. aegypti decrease with increasing salinity, and percent body water is constant across salinities. As for O. taeniorhynchus, duration of A. aegypti larval stage increases at high salinity. However, this increase in larval stage duration cannot compensate for the decrease in growth rate at high salinity, resulting in an overall decrease in both wet and dry pupal mass at high salinity. Thus, salinity has fundamentally different effects on developmental programs and phenotypic plasticity in the two species investigated. PMID:15159433

Clark, Thomas M; Flis, Benjamin J; Remold, Susanna K



High cyanobacterial nifH gene diversity in Arctic seawater and sea ice brine.  


Although cyanobacterial diazotrophs are common in Arctic terrestrial and freshwater habitats, they have been assumed to be absent from Arctic marine habitats. We report here a high diversity of cyanobacterial nifH genes in Fram Strait and the Greenland Sea. The nifH gene encodes the iron protein of the nitrogenase enzyme complex, which is essential for biological N2 fixation. Using primers specific for nifH genes we uncovered communities of autotrophic and heterotrophic bacteria in sea ice brine and seawater between latitudes 65 and 81°N. Cyanobacteria (Oscillatoriales and Chroococcales) with known marine planktonic and benthic distributions were distinguished, alongside a mix of metabolically versatile eubacteria (nifH Clusters I and III). Using primers selective for cyanobacterial nifH genes we identified filamentous non-heterocystous Trichodesmium-like and LPP (Leptolyngbya, Phormidium and Plectonema)-like Oscillatoriales, as well as Cyanothece-like Chroococcales in a brine sample from 81°N. The occurrence of Trichodesmium-like cyanobacteria was further confirmed by sequences of the hetR gene of Trichodesmium. Microscopic examinations confirmed the presence of viable filamentous and unicellular cyanobacteria. Our results reveal the potential for microbial N2 fixation in the Arctic seas. However, it is still left to determine if these genes are also metabolically active before any biogeochemical importance of diazotrophy in the polar oceans can be assessed. PMID:23760800

Díez, Beatriz; Bergman, Birgitta; Pedrós-Alió, Carlos; Antó, Meritxell; Snoeijs, Pauline



Phycobilisomes linker family in cyanobacterial genomes: divergence and evolution  

PubMed Central

Cyanobacteria are the oldest life form making important contributions to global CO2 fixation on the Earth. Phycobilisomes (PBSs) are the major light harvesting systems of most cyanobacteria species. Recent availability of the whole genome database of cyanobacteria provides us a global and further view on the complex structural PBSs. A PBSs linker family is crucial in structure and function of major light-harvesting PBSs complexes. Linker polypeptides are considered to have the same ancestor with other phycobiliproteins (PBPs), and might have been diverged and evolved under particularly selective forces together. In this paper, a total of 192 putative linkers including 167 putative PBSs-associated linker genes and 25 Ferredoxin-NADP oxidoreductase (FNR) genes were detected through whole genome analysis of all 25 cyanobacterial genomes (20 finished and 5 in draft state). We compared the PBSs linker family of cyanobacteria in terms of gene structure, chromosome location, conservation domain, and polymorphic variants, and discussed the features and functions of the PBSs linker family. Most of PBSs-associated linkers in PBSs linker family are assembled into gene clusters with PBPs. A phylogenetic analysis based on protein data demonstrates a possibility of six classes of the linker family in cyanobacteria. Emergence, divergence, and disappearance of PBSs linkers among cyanobacterial species were due to speciation, gene duplication, gene transfer, or gene loss, and acclimation to various environmental selective pressures especially light.

Guan, Xiangyu; Qin, Song; Zhao, Fangqing; Zhang, Xiaowen; Tang, Xuexi



Sources of edaphic cyanobacterial diversity in the Dry Valleys of Eastern Antarctica.  


Cyanobacteria are major components of Antarctic Dry Valley ecosystems. Their occurrence in lakes and ponds is well documented, however, less is known about their distribution in edaphic environments. There has been considerable debate about the contribution of aquatic organic matter derived largely from cyanobacteria to terrestrial ecosystems. In this study, automated rRNA intergenic spacer analysis (ARISA) and 16S rRNA gene clone libraries were used to investigate cyanobacterial diversity in a range of soil environments within the Miers and Beacon Valleys. These data were used to elucidate the input of aquatic cyanobacteria to soil communities. Thirty-eight samples were collected from a variety of soil environments including dry and moist soils, hypoliths and lake and hydroterrestrial microbial mats. The results from the ARISA and 16S rRNA clone library analysis demonstrated that diverse cyanobacterial communities exist within the mineral soils of the Miers Valley. The soil samples from Beacon Valley were depauparate in cyanobacterial signals. Within Miers Valley, significant portions (29%-58%) of ARISA fragment lengths found in aquatic cyanobacterial mats were also present in soil and hypolith samples, indicating that lacustrine and hydroterrestrial cyanobacteria play a significant role in structuring soil communities. The influence of abiotic variables on the community structure of soil samples was assessed using BEST analysis. The results of BEST analysis of samples from within Miers Valley showed that total percentage of carbon content was the most important variable in explaining differences in cyanobacterial community structure. The BEST analyses indicated that four elements contributed significantly to species compositional differences between valleys. We suggest that the complete absence of lakes or ponds from Beacon Valley is a contributing factor to the low cyanobacterial component of these soils. PMID:18239611

Wood, Susanna A; Rueckert, Andreas; Cowan, Donald A; Cary, S Craig



The evolutionary species pool hypothesis and patterns of freshwater diatom diversity along a pH gradient  

Microsoft Academic Search

Aim To interpret the unimodal relationship between diatom species richness and lake pH within the context of the evolutionary species pool hypothesis (SPH). We test the following primary prediction arising from the SPH: the size of the potential species pool (PSP) will increase along a gradient representing the historical commonness of different pH environments (pH commonness). To do this we

Jason Pither; Lonnie W. Aarssen



High salinity alters chloroplast morpho-physiology in a freshwater Kirchneriella species (Selenastraceae) from Ethiopian Lake Awasa.  


Plants differ in their ability to tolerate salt stress. In aquatic ecosystems, it is important to know the responses of microalgae to increased salinity levels, especially considering that global warming will increase salinity levels in some regions of the Earth, e.g., Ethiopia. A green microalga, Kirchneriella sp. (Selenastraceae, Chlorophyta), isolated from freshwater Lake Awasa in the Rift Valley, Ethiopia, was cultured in media amended with 0, 0.4, 1.9, 5.9, and 19.4 g NaCl·L(-1) adjusted with NaCl to five salinity levels adjusted with NaCl. Growth was monitored for 3 mo, then samples were collected for photosynthetic pigment determinations, microspectrofluorimetric analyses, and micro- and submicroscopic examinations. The best growth was found at 1.9 g NaCl·L(-1). In the chloroplast, excess NaCl affected the coupling of light harvesting complex II and photosystem II (LHCII-PSII), but changes in thylakoid architecture and in the PSII assembly state allowed sufficient integrity of the photosynthetic membrane. The mucilaginous capsule around the cell probably provided partial protection against NaCl excess. On the whole, the microalga is able to acclimate to a range of NaCl concentrations, and this plasticity indicates that Kirchneriella sp. may survive future changes in water quality. PMID:21636392

Ferroni, Lorenzo; Baldisserotto, Costanza; Pantaleoni, Laura; Billi, Paolo; Fasulo, Maria P; Pancaldi, Simonetta



Phylogeography of the Italian vairone (Telestes muticellus, Bonaparte 1837) inferred by microsatellite markers: evolutionary history of a freshwater fish species with a restricted and fragmented distribution  

PubMed Central

Background Owing to its independence from the main Central European drainage systems, the Italian freshwater fauna is characterized by a high degree of endemicity. Three main ichthyogeographic districts have been proposed in Italy. Yet, the validity of these regions has not been confirmed by phylogenetic and population genetic analyses and a phylogeographic scenario for Italy's primary freshwater fish fauna is still lacking. Here, we investigate the phylogeography of the Italian vairone (Telestes muticellus). Results We sampled 38 populations representing the species' entire distribution range and covering all relevant drainage systems, and genotyped 509 individuals at eight variable microsatellite loci. Applying various population genetic analyses, we identify five distinct groups of populations that are only partly in agreement with the proposed ichthyogeographic districts. Our group I, which is formed by specimens from Veneto and the Po River system draining into the Adriatic Sea, corresponds to the Padano-Venetian ichthyogeographic district (PV), except for two Middle Adriatic drainages, which we identify as a separate group (III). The Tuscano-Latium district (TL) is equivalent to our group V. A more complex picture emerges for the Ligurian drainages: populations from Central Liguria belong to group I, while populations from West (group II) and East Liguria (group IV) form their own groups, albeit with affinities to PV and TL, respectively. Conclusions We propose a phylogeographic scenario for T. muticellus in which an initial T. muticellus stock became isolated from the 'Alpine' clade and survived the various glaciation cycles in several refugia. These were situated in the Upper Adriatic (groups I and II), the Middle Adriatic (group III), (East) Liguria (group IV) and Tuscano-Latium (group V). The population structure in the vairone is, in principal, in agreement with the two main ichthyogeographic districts (PV and TL), except for the two populations in the Middle Adriatic, which we identify as additional major "district".



Mercury species of sediment and fish in freshwater fish ponds around the Pearl River Delta, PR China: human health risk assessment.  


This study investigated total mercury (THg) and methylmercury (MeHg) concentrations in five species of freshwater fish and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The concentrations of THg and MeHg in fish pond surface sediments were 33.1-386 ng g(-1) dry wt and 0.18-1.25 ng g(-1) dry wt, respectively. The age of ponds affected the surface sediment MeHg concentration. The vertical distribution of MeHg in sediment cores showed that MeHg concentrations decreased with increasing depth in the top 10 cm. In addition, a significant correlation was observed between %MeHg and DNA from Desulfovibrionacaea or Desulfobulbus (p<0.05) in sediment cores. Concentrations of THg and MeHg in fish muscles ranged from 7.43-76.7 to 5.93-76.1 ng g(-1) wet wt, respectively, with significant linear relationships (r=0.97, p<0.01, n=122) observed between THg and MeHg levels in fish. A significant correlation between THg concentrations in fish (herbivorous: r=0.71, p<0.05, n=7; carnivorous: r=0.77, p<0.05, n=11) and corresponding sediments was also obtained. Risk assessment indicated that the consumption of largemouth bass and mandarin fish would result in higher estimated daily intakes (EDIs) of MeHg than reference dose (RfD) for both adults and children. PMID:21272914

Shao, Dingding; Liang, Peng; Kang, Yuan; Wang, Hongsheng; Cheng, Zhang; Wu, Shengchun; Shi, Jianbo; Lo, Samuel Chun Lap; Wang, Wenxiong; Wong, Ming H



Efficacy of New Inexpensive Cyanobacterial Biofertilizer Including its Shelflife  

Microsoft Academic Search

Summary  Four cyanobacterial inoculants all significantly increased grain and straw yield of rice either alone or in combination with\\u000a chemical fertilizer. A saving of 25 kg N ha?1 can be attained through cyanobacterial fertilization. Tobacco waste-based cyanobacterial biofertilizer was best in performance.\\u000a Cyanobacterial acetylene reducing activity in vivo varied from 144 to 255 ?mol C2H4 m?2 h?1 in different treatments, being highest for tobacco-based cyanobacterial biofertilizer integrated

M. N. Jha; A. N. Prasad



Freshwater Habitats  

NSDL National Science Digital Library

This lesson plan is part of the lesson plan library for grades 6-8. Students conduct research by sampling organisms in a nearby freshwater habitat to determine how an organism's behavior and adaptation relate to its habitat, and how freshwater habitats have different characteristics depending on whether water is still or moving. Included are objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.


Species-specific responses of two benthic invertebrates explain their distribution along environmental gradients in freshwater habitats.  


The absence of species in polluted sediments does not necessarily imply exclusion due to toxicity. Other factors, like for instance food availability and oxygen content, could also partly cause their absence. Hence, knowledge of the (combinations of) factors acting on individual organisms is essential in order to understand how populations can persist in polluted sediments. In this study species-specific responses of two benthic invertebrate species, the mayfly Ephoron virgo and the midge Chironomus riparius, to environmental variables were compared. It was assessed how these responses determine the distribution of these species in polluted sediments. Subsequently, it was discussed how these results can assist in the formulation and implementation of policies with respect to the ecological risks of pollution to benthic invertebrates. The present study showed that sediment pollution is likely to act only occasionally as a single selective force reducing the persistence of sensitive species. Yet, it was shown in our studies that the pollution level in some tested sediments limits the persistence of insects with the sensitivity of E. virgo. In other cases, however, a combination of conditions is likely to determine their persistence. As shown here for C. riparius, sediment pollution drives this species close to intoxication, but a high availability of food enables them to persist very well. The present study provides evidence that pollution levels exceeding current Dutch Negligible Concentrations may pose a detectable ecological effect at least for sensitive benthic invertebrates. PMID:18620736

de Haas, Elske M; Kraak, Michiel H S



Mechanism study on the frequent variations of cell-bound microcystins in cyanobacterial blooms in Lake Taihu: implications for water quality monitoring and assessments.  


Although Microcystis-based toxins have been intensively studied, previous studies using laboratory cultures of Microcystis strains are difficult to explain the phenomenon that microcystin concentrations and toxin variants in natural blooms differ widely and frequently within a short-term period. The present study was designed to unravel the mechanisms for the frequent variations of intracellular toxins related to the differences in cyanobacterial colonies during bloom seasons in Lake Taihu, China. Monitoring of Microcystis colonies during warm seasons indicated that the variations in microcystins in both concentrations and toxin species were associated with the frequent alteration of Microcystis colonies in Lake Taihu. High concentration of microcystins in the blooms was always associated with two Microcystis colonies, Microcystis flos-aquae and Microcystis aeruginosa, whereas when Microcystis wesenbergii was the dominant colonial type, the toxin production of the blooms was low. Additionally, environmental factors such as temperature and nutrition were also shown to have an effect on the toxin production of the blooms, and may also potentially influence the Microcystis species present. The results of the present study provides insight into a new consideration for quick water quality monitoring, assessment and risk alert in cyanobacterium- and toxin-contaminated freshwaters, which will be beneficial not only for water agencies but also for public health. PMID:19853885

Chen, Wei; Peng, Liang; Wan, Neng; Song, Lirong



Cyanobacterial Cyclopeptides as Lead Compounds to Novel Targeted Cancer Drugs  

PubMed Central

Cyanobacterial cyclopeptides, including microcystins and nodularins, are considered a health hazard to humans due to the possible toxic effects of high consumption. From a pharmacological standpoint, microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cellular damage following uptake via organic anion-transporting polypeptides (OATP). Their intracellular biological effects involve inhibition of catalytic subunits of protein phosphatase 1 (PP1) and PP2, glutathione depletion and generation of reactive oxygen species (ROS). Interestingly, certain OATPs are prominently expressed in cancers as compared to normal tissues, qualifying MC as potential candidates for cancer drug development. In the era of targeted cancer therapy, cyanotoxins comprise a rich source of natural cytotoxic compounds with a potential to target cancers expressing specific uptake transporters. Moreover, their structure offers opportunities for combinatorial engineering to enhance the therapeutic index and resolve organ-specific toxicity issues. In this article, we revisit cyanobacterial cyclopeptides as potential novel targets for anticancer drugs by summarizing existing biomedical evidence, presenting structure-activity data and discussing developmental perspectives.

Sainis, Ioannis; Fokas, Demosthenes; Vareli, Katerina; Tzakos, Andreas G.; Kounnis, Valentinos; Briasoulis, Evangelos



Occurrence of the cyanobacterial toxin cylindrospermopsin in northeast Germany.  


The frequent occurrence of the cyanobacterial toxin cylindrospermopsin (CYN) in the (sub)tropics has been largely associated with cyanobacteria of the order Nostocales of tropical origin, in particular Cylindrospermopsis raciborskii. C. raciborskii is currently observed to spread northwards into temperate climatic zones. In addition, further cyanobacteria of the order Nostocales typically inhabiting water bodies in temperate regions are being identified as CYN-producers. Therefore, data on the distribution of CYN in temperate regions are necessary for a first assessment of potential risks due to CYN in water used for drinking and recreation. A total of 127 lakes situated in the north-eastern part of Germany were investigated in 2004 for the presence of the toxin CYN and the phytoplankton composition. The toxin could be detected in half of the lakes (n = 63) and in half of 165 samples (n = 88). Concentrations reached up to 73.2 microg CYN/g DW. CYN thus proved more widely distributed than previously demonstrated. The analyses of phytoplankton data suggest Aphanizomenon sp. and Anabaena sp. as important CYN producers in Germany, and confirm recent findings of Aphanizomenon flos-aquae as CYN-producing species frequently inhabiting water bodies in temperate climatic regions. The data shown here suggest that CYN may be an important cyanobacterial toxin in German water bodies and that further data are needed to assess this. PMID:17295278

Fastner, Jutta; Rücker, Jacqueline; Stüken, Anke; Preussel, Karina; Nixdorf, Brigitte; Chorus, Ingrid; Köhler, Antje; Wiedner, Claudia



Freshwater Wetlands.  

ERIC Educational Resources Information Center

|Provides descriptions about freshwater wetlands, such as marshes, swamps, and bogs. Contains three learning activities which deal with unusual wetland plants, the animals and plants in a typical marsh, and the effects of a draught on a swamp. Included are reproducible handouts and worksheets for two of the activities. (TW)|

Naturescope, 1986



A new microphallid (Digenea) species from Lontra provocax (Mammalia: Mustelidae) from freshwater environments of northwestern Patagonia (Argentina).  


A new microphallid species of Maritrema is described from the native southern river otter, Lontra provocax (Thomas). A naturally infected otter was found dead in the Nahuel Huapi National Park, Argentina. Ovigerous adult worms were recovered from the anterior portion of the intestine. Specimens of Maritrema huillini n. sp. have an unarmed genital pore and glabrous cirrus. They can be distinguished from all other species in the genus by having a long intestinal ceca extending up to three-quarters of the testes length to the level of the posterior border of the testes and a metraterm composed of a proximal sphincter, a non-muscular sac, and a distal muscular portion. This microphallid is the first species recovered from a South American eutherian host and the first digenean recorded for L. provocax. PMID:22540416

Flores, Verónica R; Brugni, Norma L; Pozzi, Carla M



Phylogeography of the Italian vairone (Telestes muticellus, Bonaparte 1837) inferred by microsatellite markers: evolutionary history of a freshwater fish species with a restricted and fragmented distribution  

Microsoft Academic Search

BACKGROUND: Owing to its independence from the main Central European drainage systems, the Italian freshwater fauna is characterized by a high degree of endemicity. Three main ichthyogeographic districts have been proposed in Italy. Yet, the validity of these regions has not been confirmed by phylogenetic and population genetic analyses and a phylogeographic scenario for Italy's primary freshwater fish fauna is

Flavio Marchetto; Serena Zaccara; Frauke M Muenzel; Walter Salzburger



Are native naiads more tolerant to pollution than exotic freshwater bivalve species? An hypothesis tested using physiological responses of three species transplanted to mercury contaminated sites in the Ebro River (NE, Spain).  


In the lower Ebro River exist the paradoxical convergence of relatively well preserved river dynamics with the historical presence of a chloralkali plant with a long history of mercury discharges and the recent invasion of foreign bivalves species. Here we performed a comparative study on two alien bivalves, the Zebra mussel and the Asian clam (Dreissena polymorpha and Corbicula fluminea), and one protected species of naiads (Psilunio littoralis), which is the most common species of the freshwater mussel assemblages in this river. Individuals of the three species were transplanted to three sites that included a clean unpolluted upstream site, a contaminated location next to the mercury source and a downstream one. The study focused on digestive gland antioxidant and oxidative stress responses such as antioxidant enzymes, glutathione S transferase, glutathione levels, metallothionein proteins, DNA strand breaks and lipid peroxidation levels. Results evidenced interspecies differences on accumulation levels of mercury, antioxidant defensive systems and oxidative tissue damage. The naiad species, despite of accumulating more mercury showed the greatest antioxidant defensive potential, which was characterized by having high constitutive activities of glutathione S transferase and inducible activities and levels of key antioxidant enzymes and glutathione. Exposed individuals of C. fluminea had moderate levels of metal accumulation, the highest activities of antioxidant enzymes but also high levels of lipid peroxidation. D. polymorpha mussels showed the lowest levels of mercury but the lowest antioxidant responses and consequently the highest levels of oxidative injuries in the DNA and of mortality. Our results support the hypothesis that naiad species might be more tolerant to pollution than exotic species. PMID:20952043

Faria, Melissa; López, Miguel Angel; Díez, Sergi; Barata, Carlos



Are cyanobacterial blooms trophic dead ends?  


Cyanobacterial blooms induce significant costs that are expected to increase in the near future. Cyanobacterial resistance to zooplankton grazing is one factor thought to promote bloom events. Yet, numerous studies on zooplankton ability to graze upon cyanobacteria have been producing contradictory results and such a puzzle might arise from the lack of direct observations in situ. Our objective was to track, using fatty acid (FA) and fatty acid stable isotope analyses (FA-SIA), the fate of cyanobacterial organic matter in the food web of a lake subjected to summer blooms of Planktothrix rubescens. A metalimnetic bloom of P. rubescens occurred in Lake Bourget (France) during the study period (May-November 2009). The bloom was especially rich in ?-linolenic acid, 18:3(n-3), but none of the considered zooplankton taxa exhibited spiking content in this particular FA. FA-SIA revealed, however, that over a quarter of 18:3(n-3) in small zooplankton (<500 ?m) was provided by P. rubescens while large cladocerans (>500 ?m) did not benefit from it. P. rubescens 18:3(n-3) could be tracked up to perch (Perca fluviatilis) young of the year (YOY) to which it contributed to ~15 % of total 18:3(n-3). Although transferred with a much lower efficiency than micro-algal organic matter, the P. rubescens bloom supported a significant share of the pelagic secondary production and did not constitute, sensu stricto, a 'trophic dead end'. The cyanobacterial bloom also provided perch YOY with components of high nutritional values at a season when these are critical for their recruitment. This cyanobacterial bloom might thus be regarded as a significant dietary bonus for juvenile fish. PMID:23129401

Perga, Marie-Elodie; Domaizon, Isabelle; Guillard, Jean; Hamelet, Valérie; Anneville, Orlane



Species diversity of freshwater hyphomycetes in some streams of Pakistan. II. Seasonal differences of fungal communities on leaves  

Microsoft Academic Search

Significantly more fungal species colonized leaves in summer, spring and autumn dur- ing the first week of submersion than in winter. Higher amounts of dry leaf mass were lost in summer, spring and autumn than in winter. Rapid loss of dry mass was accom- panied by rapid development of a fungal community. Colonization and sporulation rates varied with each fungal

Syed H. Iqbal


A versatile net selectivity model, with application to Pacific salmon and freshwater species of the Yukon River, Alaska  

Microsoft Academic Search

Gillnet catch data from the lower Yukon River, AK, collected from 1990 to 2003 in conjunction with a sonar study to estimate the abundance of migrating fish, were assembled. The full dataset contained 92,029 records with complete species and length information. A subset of data for the eight most prevalent groups of fish was selected for the estimation of net

Jeffrey F. Bromaghin



A parasite-host checklist for Monogenea from freshwater fishes in Australia, with comments on biodiversity  

Microsoft Academic Search

During a study of the Monogenea from some Australian native freshwater fishes found in south-east Queensland, a review of the literature was made to enumerate Australia's freshwater monogenean fauna. Twenty-six named species of Monogenea have been described from 16 species of native freshwater fishes. A further 16 records of monogeneans have been reported from native and introduced freshwater fishes, but

Adam S. Fletcher; Ian D. Whittington



Screening for cyanobacterial hepatotoxins, microcystins and nodularin in environmental water samples by reversed-phase liquid chromatography–electrospray ionisation mass spectrometry  

Microsoft Academic Search

Water samples taken from 93 freshwater and brackish water locations in Åland (SW Finland) in 2001 were analysed for biomass-bound microcystins and nodularin, cyanobacterial peptide hepatotoxins, by liquid chromatography–mass spectrometry (LC–MS) in selected ion recording (SIR) and multiple reaction monitoring modes, HPLC–UV, and enzyme-linked immunosorbent assay (ELISA). The extracted toxins were separated on a short C18 column with a gradient

Lisa Spoof; Pia Vesterkvist; Tore Lindholm; Jussi Meriluoto



Nitrate (NO 3?N) toxicity to aquatic life: A proposal of safe concentrations for two species of nearctic freshwater invertebrates  

Microsoft Academic Search

Safe concentrations (SCs) of nitrate (NO3?N) for early and last instar larvae of two species of Nearctic net-spinning caddisflies, Cheumatopsyche pettiti and Hydropsyche occidentalis, are estimated from short-term toxicity bioassays using an innovative methodology, the multifactor probit analysis (MPA) software. Toxicity bioassays were conducted in soft water (average hardness value of 42.7 ppm CaCO3). Larvae were exposed to five different

J. A. Camargo; J. V. Ward



Mussel isotope signature as indicator of nutrient pollution in a freshwater eutrophic lake: species, spatial, and seasonal variability  

Microsoft Academic Search

Stable nitrogen isotope ratios of five mussel species from littoral and pelagic areas were investigated with different trophic\\u000a states in the eutrophic Lake Taihu, the third largest lake in China. Interpopulation variability for these mussels was relatively\\u000a small in foot tissues because of the slow turnover time. Seasonal and spatial variations among the ?\\u000a 15N values of mussels might be

Zhourui Wen; Ping Xie; Jun Xu



Sexual disruption in a second species of wild cyprinid fish (the gudgeon, Gobio gobio) in United Kingdom freshwaters.  


To establish whether the intersex condition seen in the roach (Rutilus rutilus) in United Kingdom (UK) rivers was species specific or a more general phenomenon in fish, evidence for sexual disruption was sought in a second cyprinid species, the gudgeon (Gobio gobio). Gudgeon were collected from the Rivers Aire and Lea (at locations that receive high-volume discharges of sewage treatment works [STW] effluent and that contain intersex roach) and from two still waters, and their gonads were examined histologically for evidence of intersexuality (the simultaneous presence of oocytes and testicular tissue). Intersex gonads were found at all sites, with the highest incidences occurring at one of the still waters (Lakeside Fisheries: 15%) and at sites on the River Aire (Thwaite Weir, Silsden Bridge, and Knostrop: 14, 13, and 12%, respectively). In the River Lea and Longton Park Lake, the incidence of intersexuality in gudgeon was 6%. In most cases, intersex gonads were characterized by a few primary oocytes/gonad section in an otherwise normal testis. However, at some sites on the River Aire (Thwaite Weir and Knostrop), the intersex condition was more severe. At Thwaite Weir, for example, more than half of the gonad in 40% of the intersex fish was comprised of ovarian tissue. Elevated concentrations of plasma vitellogenin both in male and in intersex fish indicated that fish had been exposed to estrogen(s). Some of the gudgeon were found at sites several kilometers downstream of any point discharge of STW effluent; therefore, the results likely are representative of this species in wild populations found in typical UK river ecosystems. Together with the findings in the roach, these data on the gudgeon confirm that sexual disruption in fish in UK rivers is not species specific. PMID:11764169

van Aerle, R; Nolan, T M; Jobling, S; Christiansen, L B; Sumpter, J P; Tyler, C R



A review of the alien and expansive species of freshwater cyanobacteria and algae in the Czech Republic  

Microsoft Academic Search

The invasion and spread of non-native species of many different kinds of organisms is of increasing interest to researchers.\\u000a Invasions by microscopic organisms, however, are poorly understood, and their impact on the environment is probably underestimated.\\u000a We collected available data on non-native and invasive\\/expansive algae and cyanobacteria in the Czech Republic; we mapped\\u000a their distribution and assessed their impact on

Jan Kaštovský; TomᚠHauer; Jan Mareš; Markéta Krautová; TomᚠBešta; Ji?í Komárek; Blanka Desortová; Ji?í Heteša; Alica Hindáková; Václav Houk; Emil Jane?ek; Radovan Kopp; Petr Marvan; Petr Pumann; Olga Skácelová; Eliška Zapom?lová



Critical swimming speed of brown trout (Salmo trutta) infested with freshwater pearl mussel (Margaritifera margaritifera) glochidia and implications for artificial breeding of an endangered mussel species.  


Unionid freshwater mussels need to attach to a host fish for completion of their life cycle. It remains unclear whether the relationship between these mussels and their host fishes can be considered parasitic, mutualistic, or commensal. Herein, we studied the effects of Margaritifera margaritifera infestation on Salmo trutta, the most important host of this endangered mussel species in Central Europe. Glochidial load of host fish increased with increasing glochidial concentration, but the highest ratios of encysted glochidia to exposed glochidia were found at low concentration (15,000 glochidia L(-1)) during infestation. Host fish mortality occurred at infestation rates of ~350 glochidia per g fish weight and was highest (60%) at the highest infestation rates (~900 glochidia per g fish weight). On a sublethal level, swimming performance of hosts was inversely related to infestation rates, with infestation of ~900 glochidia per g fish weight reducing critical swimming speed of S. trutta significantly by ~20% compared to infestation with 6 glochidia per g fish weight. The high mortality and the impaired swimming capability of highly infested hosts indicate a parasitic interaction between M. margaritifera and its host. For conservation and reintroduction of M. margaritifera via glochidia-infested S. trutta, we recommend glochidial loads of 5-100 glochidia per g fish weight, while for artificial breeding of juvenile M. margaritifera under laboratory conditions, higher infestation rates of up to 300 glochidia per g fish weight are ideal to balance high yields of mussels and welfare of host fishes. PMID:23377147

Taeubert, Jens-Eike; Geist, Juergen



Effects of rainfall patterns on toxic cyanobacterial blooms in a changing climate: between simplistic scenarios and complex dynamics.  


Toxic cyanobacterial blooms represent a serious hazard to environmental and human health, and the management and restoration of affected waterbodies can be challenging. While cyanobacterial blooms are already a frequent occurrence, in the future their incidence and severity are predicted to increase due to climate change. Climate change is predicted to lead to increased temperature and changes in rainfall patterns, which will both have a significant impact on inland water resources. While many studies indicate that a higher temperature will favour cyanobacterial bloom occurrences, the impact of changed rainfall patterns is widely under-researched and therefore less understood. This review synthesizes the predicted changes in rainfall patterns and their potential impact on inland waterbodies, and identifies mechanisms that influence the occurrence and severity of toxic cyanobacterial blooms. It is predicted that there will be a higher frequency and intensity of rainfall events with longer drought periods in between. Such changes in the rainfall patterns will lead to favourable conditions for cyanobacterial growth due to a greater nutrient input into waterbodies during heavy rainfall events, combined with potentially longer periods of high evaporation and stratification. These conditions are likely to lead to an acceleration of the eutrophication process and prolonged warm periods without mixing of the water column. However, the frequent occurrence of heavy rain events can also lead to a temporary disruption of cyanobacterial blooms due to flushing and de-stratification, and large storm events have been shown to have a long-term negative effect on cyanobacterial blooms. In contrast, a higher number of small rainfall events or wet days can lead to proliferation of cyanobacteria, as they can rapidly use nutrients that are added during rainfall events, especially if stratification remains unchanged. With rainfall patterns changing, cyanobacterial toxin concentration in waterbodies is expected to increase. Firstly, this is due to accelerated eutrophication which supports higher cyanobacterial biomass. Secondly, predicted changes in rainfall patterns produce more favourable growth conditions for cyanobacteria, which is likely to increase the toxin production rate. However, the toxin concentration in inland waterbodies will also depend on the effect of rainfall events on cyanobacterial strain succession, a process that is still little understood. Low light conditions after heavy rainfall events might favour non-toxic strains, whilst inorganic nutrient input might promote the dominance of toxic strains in blooms. This review emphasizes that the impact of changes in rainfall patterns is very complex and will strongly depend on the site-specific dynamics, cyanobacterial species composition and cyanobacterial strain succession. More effort is needed to understand the relationship between rainfall patterns and cyanobacterial bloom dynamics, and in particular toxin production, to be able to assess and mediate the significant threat cyanobacterial blooms pose to our water resources. PMID:22169160

Reichwaldt, Elke S; Ghadouani, Anas



Global diversity of amphibians (Amphibia) in freshwater  

Microsoft Academic Search

This article present a review of species numbers, biogeographic patterns and evolutionary trends of amphibians in freshwater.\\u000a Although most amphibians live in freshwater in at least their larval phase, many species have evolved different degrees of\\u000a independence from water including direct terrestrial development and viviparity. Of a total of 5,828 amphibian species considered\\u000a here, 4,117 are aquatic in that they

Miguel Vences; Jörn Köhler



Global diversity of amphibians (Amphibia) in freshwater  

Microsoft Academic Search

This article present a review of species numbers, biogeographic patterns and evolutionary trends of amphibians in freshwater.\\u000a Although most amphibians live in freshwater in at least their larval phase, many species have evolved different degrees of\\u000a independence from water including direct terrestrial development and viviparity. Of a total of 5,828 amphibian species considered\\u000a here, 4,117 are aquatic in that they

Miguel Vences; Jörn Köhler


The biogeography and phylogeny of unicellular cyanobacterial symbionts in sponges from Australia and the Mediterranean.  


The distribution, host associations, and phylogenetic relationships of the unicellular cyanobacterial symbionts of selected marine sponges were investigated with direct 16s rDNA sequencing. The results indicate that the symbionts of the marine sponges Aplysina aerophoba, Ircinia variabilis, and Petrosia ficiformis from the Mediterranean, four Chondrilla species from Australia and the Mediterranean, and Haliclona sp. from Australia support a diversity of symbionts comprising at least four closely related species of Synechococcus. These include the symbionts presently described as Aphanocapsa feldmannii from P. ficiformis and Chondrilla nucula. A fifth symbiont from Cymbastela marshae in Australia is an undescribed symbiont of sponges, related to Oscillatoria rosea. One symbiont, Candidatus Synechococcus spongiarum, was found in diverse sponge genera in the Mediterranean Sea and the Indian, Pacific, and Southern oceans, whereas others were apparently more restricted in host association and distribution. These results are discussed in terms of the biodiversity and biogeographic distributions of cyanobacterial symbionts. PMID:15546037

Usher, K M; Fromont, J; Sutton, D C; Toze, S



Mussel isotope signature as indicator of nutrient pollution in a freshwater eutrophic lake: species, spatial, and seasonal variability.  


Stable nitrogen isotope ratios of five mussel species from littoral and pelagic areas were investigated with different trophic states in the eutrophic Lake Taihu, the third largest lake in China. Interpopulation variability for these mussels was relatively small in foot tissues because of the slow turnover time. Seasonal and spatial variations among the delta (15)N values of mussels might be due in part to the natural variation in delta (15)N values of potential food sources and the variation in the amount of human pollutions discharged into various locations of the lake. Although the increase of mussel delta (15)N values was accompanied by the increase of nutrient concentrations in most situations in this study, statistically significant correlations were only 22% of the total correlations in this survey, which might be attributed to the different time-scale variations in nutrient concentrations and isotope signatures and the unknown details of the trophic pathways and metabolism for incorporation of these nutrients. PMID:19274484

Wen, Zhourui; Xie, Ping; Xu, Jun



Cytotoxicity Screening for the Cyanobacterial Toxin Cylindrospermopsin  

Microsoft Academic Search

The cell lines C3A, HepG2, NCI-87, HCT-8, HuTu-80, Caco-2, and Vero were screened for sensitivity to the cyanobacterial toxin cylindrospermopsin (CYN), with the aim of determining the most sensitive cells to be used in cytotoxicity tests. Cell lines were chosen to be representative of the organs targeted by the toxin; liver, kidney, intestine, and were expected to have different metabolic

Suzanne M. Froscio; Stella Fanok; Andrew R. Humpage



Total mercury distribution in different tissues of six species of freshwater fish from the Kpong hydroelectric reservoir in Ghana.  


Total mercury concentrations were determined in seven tissues of 38 fish samples comprising six species from the Kpong hydroelectric reservoir in Ghana by cold vapour atomic absorption spectrometry technique using an automatic mercury analyzer. Mercury concentration in all the tissues ranged from 0.005 to 0.022 ?g/g wet weight. In general, the concentration of mercury in all the tissues were decreasing in the order; liver?>?muscle?>?intestine?>?stomach?>?gonad?>?gill?>?swim bladder. Mercury concentration was generally greater in the tissues of high-trophic-level fish such as Clarotes laticeps, Mormyrops anguilloides and Chrysichthys aurutus whereas low-trophic-level fish such as Oreochromis niloticus recorded low mercury concentration in their tissues. The results obtained for total mercury concentration in the muscle tissues analysed in this study are below the WHO/FAO threshold limit of 0.5 ?g/g. This suggests that the exposure of the general public to Hg through fish consumption can be considered negligible. PMID:21713471

Atta, Alhassan; Voegborlo, Ray Bright; Agorku, Eric Selorm



In Brief: Europe's freshwater fish threatened  

NASA Astrophysics Data System (ADS)

Two hundred of Europe's 522 freshwater fish species are threatened with extinction and 12 are already extinct, according to the Handbook of European Freshwater Fishes, published in collaboration with the World Conservation Union (IUCN) and released on 1 November 2007. IUCN notes that the main threats to fish species stem from development and population growth and include water withdrawals, large dams, and inappropriate fisheries management that has led to overfishing and the introduction of alien species. Authors Maurice Kottelat, former president of the European Ichthyological Society, and Jörg Freyhof, scientist from Leibniz Institute of Freshwater Ecology, noted that fish conservation should be managed by agencies in charge of conservation, and not as a crop by agencies in charge of agriculture. William Darwall, senior program officer with IUCN's Species Program, said the species ``are critical to the freshwater ecosystems upon which we do depend, such as for water purification and flood control.'' For more information, visit the Web site:

Showstack, Randy



Harmful cyanobacterial blooms: causes, consequences, and controls.  


Cyanobacteria are the Earth's oldest oxygenic photoautotrophs and have had major impacts on shaping its biosphere. Their long evolutionary history (? 3.5 by) has enabled them to adapt to geochemical and climatic changes, and more recently anthropogenic modifications of aquatic environments, including nutrient over-enrichment (eutrophication), water diversions, withdrawals, and salinization. Many cyanobacterial genera exhibit optimal growth rates and bloom potentials at relatively high water temperatures; hence global warming plays a key role in their expansion and persistence. Bloom-forming cyanobacterial taxa can be harmful from environmental, organismal, and human health perspectives by outcompeting beneficial phytoplankton, depleting oxygen upon bloom senescence, and producing a variety of toxic secondary metabolites (e.g., cyanotoxins). How environmental factors impact cyanotoxin production is the subject of ongoing research, but nutrient (N, P and trace metals) supply rates, light, temperature, oxidative stressors, interactions with other biota (bacteria, viruses and animal grazers), and most likely, the combined effects of these factors are all involved. Accordingly, strategies aimed at controlling and mitigating harmful blooms have focused on manipulating these dynamic factors. The applicability and feasibility of various controls and management approaches is discussed for natural waters and drinking water supplies. Strategies based on physical, chemical, and biological manipulations of specific factors show promise; however, a key underlying approach that should be considered in almost all instances is nutrient (both N and P) input reductions; which have been shown to effectively reduce cyanobacterial biomass, and therefore limit health risks and frequencies of hypoxic events. PMID:23314096

Paerl, Hans W; Otten, Timothy G



Cyanobacterial toxin degrading bacteria: who are they?  


Cyanobacteria are ubiquitous in nature and are both beneficial and detrimental to humans. Benefits include being food supplements and producing bioactive compounds, like antimicrobial and anticancer substances, while their detrimental effects are evident by toxin production, causing major ecological problems at the ecosystem level. To date, there are several ways to degrade or transform these toxins by chemical methods, while the biodegradation of these compounds is understudied. In this paper, we present a meta-analysis of the currently available 16S rRNA and mlrA (microcystinase) genes diversity of isolates known to degrade cyanobacterial toxins. The available data revealed that these bacteria belong primarily to the Proteobacteria, with several strains from the sphingomonads, and one from each of the Methylobacillus and Paucibacter genera. Other strains belonged to the genera Arthrobacter, Bacillus, and Lactobacillus. By combining the ecological knowledge on the distribution, abundance, and ecophysiology of the bacteria that cooccur with toxic cyanobacterial blooms and newly developed molecular approaches, it is possible not only to discover more strains with cyanobacterial toxin degradation abilities, but also to reveal the genes associated with the degradation of these toxins. PMID:23841072

Kormas, Konstantinos Ar; Lymperopoulou, Despoina S



Gill (Na+,K+)-ATPase in diadromous, freshwater palaemonid shrimps: species-specific kinetic characteristics and alpha-subunit expression.  


To better comprehend physiological adaptation to dilute media and the molecular mechanisms underlying ammonia excretion in palaemonid shrimps, we characterized the (Na+,K+)-ATPase from Macrobrachium amazonicum gills, disclosing high- (K(0.5) = 4.2+/-0.2 micromol L(-1); V = 33.9+/-1.9 U mg(-1)) and low-affinity (K(0.5) = 0.144+/-0.010 mmol L(-1); V = 232.9+/-15.3 U mg(-1)) ATP hydrolyzing sites. Stimulation by Na+ (K(0.5) = 5.5+/-0.3 mmol L(-1); V = 275.1+/-15.1 U mg(-1)), Mg2+ (K(0.5) = 0.79+/-0.06 mmol L(-1); V = 261.9+/-18.3 U mg(-1)), K+ (K(M) = 0.88+/-0.04 mmol L(-1); V = 271.8+/-10.9 U mg(-1)) and NH4(+) (K(M) = 5.0+/-0.2 mmol L(-1); V = 385.9+/-15.8 U mg(-1)) obeys single saturation curves, activity being stimulated synergistically by NH4(+) and K+. There is a single K+ binding site, NH4(+) binding to a second, exclusive site, stimulating activity by 33%, modulating K+ affinity. (Na+,K+)-ATPase activity constitutes approximately 80% of total ATPase activity (K(Iouabain) = 147.5+/-8.9 micromol L(-1)); Na+-, K+-, Ca2+-, V- and F(o)F(1)-ATPases are also present. M. amazonicum microsomal fractions possess approximately 2-fold less (Na+,K+)-ATPase alpha-subunit than M. olfersi, consistent with a 2.6-fold lower specific activity. These differences in (Na+, K+)-ATPase stimulation by ATP and ions, and specific activities of other ATPases, suggest the presence of distinct biochemical adaptations to life in fresh water in these related species. PMID:17521934

Santos, L C F; Belli, N M; Augusto, A; Masui, D C; Leone, F A; McNamara, J C; Furriel, R P M



Freshwater Sculpins: Phylogenetics to Ecology  

Microsoft Academic Search

Freshwater sculpins (Cottidae) are a diverse and ecologically important component of cool- and coldwater ecosystems throughout the northern hemisphere. More than 60 sculpin species occur in a variety of habitats, and sculpin distributions range from highly localized to widespread. Despite the frequently high biomass of sculpins and their numerous ecosystem functions, the traditional fisheries management emphasis on sport fishes has

Susan B. Adams; David A. Schmetterling



Human?assisted dispersal of alien freshwater fish in Australia  

Microsoft Academic Search

Approximately 34 alien fish species have established populations in Australian freshwaters with a further 53 native fish species translocated within the country. Twelve pathways of human?assisted dispersal for freshwater fish have been identified in Australia, and each is discussed with examples given. The major pathway has been the aquarium or ornamental fish industry, with 22 of the 34 alien species

Mark Lintermans



Freshwater Flow Charts - 1995  

SciTech Connect

This report covers the following: (1) Explanation of Charts Showing Freshwater Flow in 1995; (2) Estimated U.S. Freshwater Flow in 1995 (chart); (3) Estimated California Freshwater Flow in 1995 (chart); (4) Estimated New Mexico Freshwater Flow in 1995 (chart); and (5) Web locations and credits.

Kaiper, G V



A toxic cyanobacterial bloom in an urban coastal lake, Rio Grande do Sul state, Southern Brazil  

PubMed Central

Reports of cyanobacterial blooms developing worldwide have considerably increased, and, in most cases, the predominant toxins are microcystins. The present study reports a cyanobacterial bloom in Lake Violão, Torres, Rio Grande do Sul State, in January 2005. Samples collected on January 13, 2005, were submitted to taxonomical, toxicological, and chemical studies. The taxonomical analysis showed many different species of cyanobacteria, and that Microcystis protocystis and Sphaerocavum cf. brasiliense were dominant. Besides these, Microcystis panniformis, Anabaena oumiana, Cylindrospermopsis raciborskii, and Anabaenopsis elenkinii f. circularis were also present. The toxicity of the bloom was confirmed through intraperitoneal tests in mice, and chemical analyses of bloom extracts showed that the major substance was anabaenopeptin F, followed by anabaenopeptin B, microcystin-LR, and microcystin-RR.

de Carvalho, Luciana Retz; Pipole, Fernando; Werner, Vera Regina; Laughinghouse IV, Haywood Dail; de Camargo, Antonio Carlos M.; Rangel, Marisa; Konno, Katsuhiro; Sant' Anna, Celia Leite



Isolation and structures of microcystins from a cyanobacterial water bloom (Finland).  


A hepatotoxic cyanobacterial (blue-green algal) water bloom was collected from a constructed water reservoir in Finland. The water bloom contained two cyanobacterial species, Microcystis aeruginosa and Aphanizomenon flos-aquae. Two hepatotoxins, 1 and 2, were isolated from extracts of lyophilized cells. The structures of 1 and 2 were assigned based upon their amino acid analyses on a Waters Pico Tag HPLC system and a chiral GC capillary column (Chirasil Val III), fast atom bombardment mass spectrometry (FABMS), high resolution FABMS, and tandem FABMS data. Toxin 1 was identical to a previously reported compound, [D-Asp3]microcystin-RR. Toxin 2 was new and was assigned the structure [D-Asp3]microcystin-YR. PMID:1485342

Namikoshi, M; Sivonen, K; Evans, W R; Sun, F; Carmichael, W W; Rinehart, K L



Lake Superior supports novel clusters of cyanobacterial picoplankton.  


Very little is known about the biodiversity of freshwater autotrophic picoplankton (APP) in the Laurentian Great Lakes, a system comprising 20% of the world's lacustrine freshwater. In this study, the genetic diversity of Lake Superior APP was examined by analyzing 16S rRNA gene and cpcBA PCR amplicons from water samples. By neighbor joining, the majority of 16S rRNA gene sequences clustered within the "picocyanobacterial clade" consisting of freshwater and marine Synechococcus and Prochlorococcus. Two new groups of Synechococcus spp., the pelagic Lake Superior clusters I and II, do not group with any of the known freshwater picocyanobacterial clusters and were the most abundant species (50 to 90% of the sequences) in samples collected from offshore Lake Superior stations. Conversely, at station Portage Deep (PD), located in a nearshore urbanized area, only 4% of the sequences belonged to these clusters and the remaining clones reflected the freshwater Synechococcus diversity described previously at sites throughout the world. Supporting the 16S rRNA gene data, the cpcBA library from nearshore station PD revealed a cosmopolitan diversity, whereas the majority of the cpcBA sequences (97.6%) from pelagic station CD1 fell within a unique Lake Superior cluster. Thus far, these picocyanobacteria have not been cultured, although their phylogenetic assignment suggests that they are phycoerythrin (PE) rich, consistent with the observation that PE-rich APP dominate Lake Superior picoplankton. Lastly, flow cytometry revealed that the summertime APP can exceed 10(5) cells ml-1 and suggests that the APP shifts from a community of PE and phycocyanin-rich picocyanobacteria and picoeukaryotes in winter to a PE-rich community in summer. PMID:17468271

Ivanikova, Natalia V; Popels, Linda C; McKay, R Michael L; Bullerjahn, George S



The world’s smallest vertebrate species of the genus Paedocypris: A new family of freshwater fishes and the sister group to the world’s most diverse clade of freshwater fishes (Teleostei: Cypriniformes)  

Microsoft Academic Search

The genus Paedocypris has only recently been discovered and described and includes three species, all of which are miniature species and one, P. progenetica, is the smallest vertebrate species. Two previous studies investigating relationships of Paedocypris, based on either cytochrome b or morphology, placed the genus with Sundadanio and Danionella, two genera with miniature species in the formerly recognized family

Richard L. Mayden; Wei-Jen Chen



Development of digestive enzymes and in vitro digestibility of different species of phytoplankton for culture of early juveniles of the freshwater pearl mussel, Hyriopsis (Hyriopsis) bialatus Simpson, 1900  

Microsoft Academic Search

In vitro culture of the glochidia of the freshwater pearl mussel, Hyriopsis (Hyriopsis) bialatus Simpson, 1900, in M199 medium supplemented with common carp plasma resulted in 95 ± 2% survival, of which 97 ± 2% were transformed to juveniles. Transformation occurred within 10 days. After transformation, early juvenile mussels were reared and fed for 15 days with a mixture of




E¡ects of an invasive cattail species (Typhaglauca )o n sediment nitrogen and microbial community composition in a freshwater wetland  

Microsoft Academic Search

Sediments from Cheboygan Marsh, a coastal freshwater wetland on Lake Huron that has been invaded by an emergent exotic plant, Typhaglauca, were examined to assess the effects of invasion on wetland nutrient levels and sediment microbial communities. Comparison of invaded and uninvaded zones of the marsh indicated that the invaded zone showed significantly lower plant diversity, as well as significantly

Nicholas L. Angeloni; Kathi Jo Jankowski; Nancy C. Tuchman; John J. Kelly


Evidence for the functioning of photosynthetic CO 2 -concentrating mechanisms in lichens containing green algal and cyanobacterial photobionts  

Microsoft Academic Search

The photosynthetic properties of a range of lichens containing both green algal (11 species) and cyanobacterial (6 species) photobionts were examined with the aim of determining if there was clear evidence for the operation of a CO2-concentrating mechanism (CCM) within the photobionts. Using a CO2-gas-exchange system, which allowed resolution of fast transients, evidence was obtained for the existence of an

Murray R. Badger; Hardy Pfanz; Burkhard Büdel; Ulrich Heber; Otto L. Lange



The presence of the cyanobacterial toxin microcystin in black band disease of corals.  


Black band disease (BBD) is a migrating, cyanobacterial dominated, sulfide-rich microbial mat that moves across coral colonies lysing coral tissue. While it is known that BBD sulfate-reducing bacteria contribute to BBD pathogenicity by production of sulfide, additional mechanisms of toxicity may be involved. Using HPLC/MS, the cyanotoxin microcystin was detected in 22 field samples of BBD collected from five coral species on nine reefs of the wider Caribbean (Florida Keys and Bahamas). Two cyanobacterial cultures isolated from BBD, Geitlerinema and Leptolyngbya sp. contained microcystin based on HPLC/MS, with toxic activity confirmed using the protein phosphatase inhibition assay. The gene mcyA from the microcystin synthesis complex was detected in two field samples and from both BBD cyanobacterial cultures. Microcystin was not detected in six BBD samples from a different area of the Caribbean (St Croix, USVI) and the Philippines, suggesting regional specificity for BBD microcystin. This is the first report of the presence of microcystin in a coral disease. PMID:17506829

Richardson, Laurie L; Sekar, Raju; Myers, Jamie L; Gantar, Miroslav; Voss, Joshua D; Kaczmarsky, Longin; Remily, Elizabeth R; Boyer, Gregory L; Zimba, Paul V



Substitutional editing of transcripts from genes of cyanobacterial origin in the dinoflagellate Ceratium horridum.  


Peridinin-containing dinoflagellates, a group of alveolate organisms, harbour small plasmids called minicircles. As most of these minicircles encode genes of cyanobacterial origin, which are also found in plastid genomes of stramenopiles, they were thought to represent the plastid genome of peridinin-containing dinoflagellates. The analyses of minicircle derived mRNAs and the 16S rRNA showed that extensive editing of minicircle gene transcripts is common for Ceratium horridum. Posttranscriptional changes occur predominantly by editing A into G, but other types of editing including a previously unreported A to C transversion were also detected. This leads to amino acid changes in most cases or, in one case, to the elimination of a stop-codon. Interestingly, the edited mRNAs show higher identities to homologous sequences of other peridinin-containing dinoflagellates than their genomic copy. Thus, our results imply that transcript editing of genes of cyanobacterial origin is species specific in peridinin-containing dinoflagellates and demonstrate that editing of genes of cyanobacterial origin is not restricted to land plants. PMID:15556642

Zauner, Stefan; Greilinger, Doris; Laatsch, Thomas; Kowallik, Klaus V; Maier, Uwe-G



Prospects for monitoring freshwater ecosystems towards the 2010 targets  

PubMed Central

Human activities have severely affected the condition of freshwater ecosystems worldwide. Physical alteration, habitat loss, water withdrawal, pollution, overexploitation and the introduction of non-native species all contribute to the decline in freshwater species. Today, freshwater species are, in general, at higher risk of extinction than those in forests, grasslands and coastal ecosystems. For North America alone, the projected extinction rate for freshwater fauna is five times greater than that for terrestrial fauna—a rate comparable to the species loss in tropical rainforest. Because many of these extinctions go unseen, the level of assessment and knowledge of the status and trends of freshwater species are still very poor, with species going extinct before they are even taxonomically classified. Increasing human population growth and achieving the sustainable development targets set forth in 2002 will place even higher demands on the already stressed freshwater ecosystems, unless an integrated approach to managing water for people and ecosystems is implemented by a broad constituency. To inform and implement policies that support an integrated approach to water management, as well as to measure progress in halting the rapid decline in freshwater species, basin-level indicators describing the condition and threats to freshwater ecosystems and species are required. This paper discusses the extent and quality of data available on the number and size of populations of freshwater species, as well as the change in the extent and condition of natural freshwater habitats. The paper presents indicators that can be applied at multiple scales, highlighting the usefulness of using remote sensing and geographical information systems technologies to fill some of the existing information gaps. Finally, the paper includes an analysis of major data gaps and information needs with respect to freshwater species to measure progress towards the 2010 biodiversity targets.

Revenga, C; Campbell, I; Abell, R; de Villiers, P; Bryer, M



Physicochemical variation of cyanobacterial starch, the insoluble ?-Glucans in cyanobacteria.  


Unicellular, diazotrophic species of cyanobacteria, Cyanobacterium sp. NBRC 102756, Cyanothece sp. ATCC 51142 and Cyanobacterium sp. CLg1, accumulate insoluble ?-glucan inside the cells as the storage polysaccharide. The purified polysaccharides showed granular morphology, with a diameter of 0.2-0.7 µm. The three ?-glucan preparations all showed A-type allomorph in X-ray diffraction analysis. Distinct thermal gelatinization temperatures were observed for these polysaccharides. The ?-glucans from NBRC 102756 and ATCC 51142 strains consisted solely of branched ?-glucans, or semi-amylopectin, while CLg1 contained semi-amylopectin as the primary component as well as linear or scarcely branched glucan (amylose). Separation of the debranched glucan chains by gel filtration chromatography explicitly showed the presence in the semi-amylopectin molecule of long chains corresponding to B2 chains, which connect clusters in amylopectin of plants. The relative proportions of short and long glucan chains in the branched polysaccharides differed depending on the species, and the variation was intimately correlated with the physical properties of the ?-glucans. The results suggested that semi-amylopectin of the three cyanobacteria exhibit essentially similar organization with a tandem cluster structure. The polysaccharides of these strains are therefore referred to as 'cyanobacterial starch', distinct from glycogen. PMID:23299410

Suzuki, Eiji; Onoda, Miho; Colleoni, Christophe; Ball, Steven; Fujita, Naoko; Nakamura, Yasunori



Zoogeography and biodiversity of the freshwater fishes of Southeast Asia  

Microsoft Academic Search

The ichthyofauna of the freshwater system of Southeast Asia is extremely diverse. A recent estimate of about 1000 species is probably an understatement. More than 10 new species are being added to the list annually. The distribution pattern of the Southeast Asian freshwater fishes can be divided into five zoogeographic regions. The first one is the Salween basin in Burma,

Mohd. Zakaria-Ismail



Implications of Dam Obstruction for Global Freshwater Fish Diversity  

Microsoft Academic Search

Dams are obstructing rivers worldwide, impairing habitat and migration opportunities for many freshwater fish species; however, global data linking dam and fish distributions have been limited. Here, we quantify dam obstruction at the biogeographic scale of freshwater ecoregion, which provides the spatial framework necessary to assess the risk of fish species loss due to dams and allows us to identify

Catherine Reidy Liermann; Christer Nilsson; James Robertson; Rebecca Y. Ng



Unveiling Distribution Patterns of Freshwater Phytoplankton by a Next Generation Sequencing Based Approach  

PubMed Central

The recognition and discrimination of phytoplankton species is one of the foundations of freshwater biodiversity research and environmental monitoring. This step is frequently a bottleneck in the analytical chain from sampling to data analysis and subsequent environmental status evaluation. Here we present phytoplankton diversity data from 49 lakes including three seasonal surveys assessed by next generation sequencing (NGS) of 16S ribosomal RNA chloroplast and cyanobacterial gene amplicons and also compare part of these datasets with identification based on morphology. Direct comparison of NGS to microscopic data from three time-series showed that NGS was able to capture the seasonality in phytoplankton succession as observed by microscopy. Still, the PCR-based approach was only semi-quantitative, and detailed NGS and microscopy taxa lists had only low taxonomic correspondence. This is probably due to, both, methodological constraints and current discrepancies in taxonomic frameworks. Discrepancies included Euglenophyta and Heterokonta that were scarce in the NGS but frequently detected by microscopy and Cyanobacteria that were in general more abundant and classified with high resolution by NGS. A deep-branching taxonomically unclassified cluster was frequently detected by NGS but could not be linked to any group identified by microscopy. NGS derived phytoplankton composition differed significantly among lakes with different trophic status, showing that our approach can resolve phytoplankton communities at a level relevant for ecosystem management. The high reproducibility and potential for standardization and parallelization makes our NGS approach an excellent candidate for simultaneous monitoring of prokaryotic and eukaryotic phytoplankton in inland waters.

Eiler, Alexander; Drakare, Stina; Bertilsson, Stefan; Pernthaler, Jakob; Peura, Sari; Rofner, Carina; Simek, Karel; Yang, Yang; Znachor, Petr; Lindstrom, Eva S.



Effects of a toxic cyanobacterial bloom (Planktothrix agardhii) on fish: insights from histopathological and quantitative proteomic assessments following the oral exposure of medaka fish (Oryzias latipes).  


Cyanobacterial toxic blooms often occur in freshwater lakes and constitute a potential health risk to human populations, as well as to fish and other aquatic organisms. Microcystin-LR (the cyanotoxin most commonly detected in the freshwater environment) is a potent hepatotoxin, deregulating the kinase pathway by inhibiting phosphatases 1 and 2A. Although toxicological effects have been clearly linked to the in vitro exposure of fish to purified microcystins, cyanotoxins are produced by the cyanobacteria together with numerous other potentially toxic molecules, and their overall and specific implications for the health of fish have still not been clearly established and remain puzzlingly difficult to assess. The medaka fish (Oryzias latipes) was chosen as an in vitro model for studying the effects of a cyanobacterial bloom on liver protein contents using a gel free quantitative approach, iTRAQ, in addition to pathology examinations on histological preparations. Fish were gavaged with 5 ?L cyanobacterial extracts (Planktothrix agardhii) from a natural bloom (La Grande Paroisse, France) containing 2.5 ?g equiv. MC-LR. 2h after exposure, the fish were sacrificed and livers were collected for analysis. Histological observations indicate that hepatocytes present glycogen storage loss, and cellular damages, together with immunological localization of MCs. Using a proteomic approach, 304 proteins were identified in the fish livers, 147 of them with a high degree of identification confidence. Fifteen of these proteins were statistically significantly different from those of controls (gavaged with water only). Overall, these protein regulation discrepancies clearly indicate that oxidative stress and lipid regulation had occurred in the livers of the exposed medaka fish. In contrast to previous pure microcystin-LR gavage experiments, marked induction of vitellogenin 1 protein was observed for the first time with a cyanobacterial extract. This finding was confirmed by ELISA quantification of vitellogenin liver content, suggesting that the Planktothrix bloom extract had induced the occurrence of an endocrine-disrupting effect. PMID:22414781

Marie, Benjamin; Huet, Hélène; Marie, Arul; Djediat, Chakib; Puiseux-Dao, Simone; Catherine, Arnaud; Trinchet, Isabelle; Edery, Marc



Freshwater fishes, their biodiversity, habitats and fisheries in the Nordic countries  

Microsoft Academic Search

Finland, Norway and Sweden have in total about 126500 lakes larger than four hectares. In Finland and Sweden, approximately 10% of the surface area is freshwater; whereas in Norway, it is about 6%. Altogether 56 fish species are reproducing in the Nordic freshwaters, including four lamprey species. Due to geographical differences, the freshwater fish fauna differs considerably in the northern

Hannu Lehtonen; Martti Rask; Susanna Pakkasmaa; Trygve Hesthagen



Integrative freshwater ecology and biodiversity conservation  

Microsoft Academic Search

Freshwater ecosystems provide goods and services of critical importance to human societies, yet they are among the most heavily altered ecosystems with an overproportional loss of biodiversity. Major threats to freshwater biodiversity include overexploitation, water pollution, fragmentation, destruction or degradation of habitat, and invasions by non-native species. Alterations of natural flow regimes by man-made dams, land-use changes, river impoundments, and

Juergen Geist



Global diversity of leeches (Hirudinea) in freshwater  

Microsoft Academic Search

Leeches (Hirudinea) constitute a relatively small monophyletic group of highly specialized annelids, but may play important\\u000a roles as invertebrate predators in freshwater, while others are infamous for their ectoparasitic bloodsucking. About 15% of\\u000a the 680 described species are marine and slightly less have switched to terrestrial life; the rest are freshwater, divided\\u000a among 91 genera. They are globally distributed on

Boris Sket; Peter Trontelj


Global diversity of leeches (Hirudinea) in freshwater  

Microsoft Academic Search

Leeches (Hirudinea) constitute a relatively small monophyletic group of highly specialized annelids, but may play important\\u000a roles as invertebrate predators in freshwater, while others are infamous for their ectoparasitic bloodsucking. About 15% of\\u000a the 680 described species are marine and slightly less have switched to terrestrial life; the rest are freshwater, divided\\u000a among 91 genera. They are globally distributed on

Boris Sket; Peter Trontelj



Microbial diversity in hot spring cyanobacterial mats: pattern and prediction  

Microsoft Academic Search

ABSTRACT Direct molecular analysis of the composition and structure of geothermal cyanobacterial mat communities,has revealed diversity patterns suggesting that adaptive radiation and geographic isolation are the important drivers of cyanobacterial diversification. Itis clear that 16S rRNA sequence variation cannot detect all ecological or geographic populations (ecotypes and geotypes, respectively), but it remains unclear what level of molecular resolution is required

Frederick M Cohan; D. M. Ward



The Bacteriology of Fresh and Spoiling Tropical Freshwater Fish.  

National Technical Information Service (NTIS)

Investigation of the bacterial flora of fish and its influence on fish spoilage have been confined largely to marine species. Comparatively, little attention has been paid to freshwater fish, particularly in the case of tropical species. In the report, an...

C. A. M. Lima dos Santos



Multi-scale strategies for the monitoring of freshwater cyanobacteria: reducing the sources of uncertainty.  


Cyanobacterial blooms are a frequent phenomenon in eutrophic freshwaters worldwide and are considered potential hazards to ecosystems and human health. Monitoring strategies based on conventional sampling often fail to cover the marked spatial and temporal variations in cyanobacterial distribution and fluctuating toxin concentrations inherent to cyanobacterial blooms. To deal with these problems, we employed a multi-scale approach for the study of a massive Microcystis bloom in Tajo River (Spain) utilizing 1) remote sensing techniques, 2) conventional water sampling and 3) analysis of chemotypical subpopulations. Tajo River at the study area is influenced by high temperatures waters diverted upstream from a nuclear power plant, the presence of a dam downstream and a high nutrient load, which provide optimal conditions for massive cyanobacterial proliferation. MERIS imagery revealed high Chl-a concentrations that rarely fell below 20 ?g L(-1) and moderate spatiotemporal variations throughout the study period (March-November 2009). Although the phytoplanktonic community was generally dominated by Microcystis, sampling points highly differed in cyanobacterial abundance and community composition. Microcystin (MC) concentrations were highly heterogeneous, varying up to 3 orders of magnitude among sampling points, exceeding in some cases WHO guideline values for drinking and also for recreational waters. The analysis of single colonies by MALDI-TOF MS revealed differences in the proportion of MC-producing colonies among points. The proportion of toxic colonies showed a highly significant linear correlation with total MC: biovolume ratio (r(2) = 0.9; p < 0.001), evidencing that the variability in toxin concentrations can be efficiently addressed by simple analysis of subpopulations. We propose implementing a multi-scale monitoring strategy that allows covering the spatiotemporal heterogeneities in both cyanobacterial distribution (remote sensing) and MC concentrations (subpopulation analysis) and thereby reduce the main sources of uncertainty in the assessment of the risks associated to bloom events. PMID:22472073

Agha, Ramsy; Cirés, Samuel; Wörmer, Lars; Domínguez, José Antonio; Quesada, Antonio



Cyanobacterial Neurotoxin ?-N-Methylamino-L-alanine (BMAA) in Shark Fins  

PubMed Central

Sharks are among the most threatened groups of marine species. Populations are declining globally to support the growing demand for shark fin soup. Sharks are known to bioaccumulate toxins that may pose health risks to consumers of shark products. The feeding habits of sharks are varied, including fish, mammals, crustaceans and plankton. The cyanobacterial neurotoxin ?-N-methylamino-L-alanine (BMAA) has been detected in species of free-living marine cyanobacteria and may bioaccumulate in the marine food web. In this study, we sampled fin clips from seven different species of sharks in South Florida to survey the occurrence of BMAA using HPLC-FD and Triple Quadrupole LC/MS/MS methods. BMAA was detected in the fins of all species examined with concentrations ranging from 144 to 1836 ng/mg wet weight. Since BMAA has been linked to neurodegenerative diseases, these results may have important relevance to human health. We suggest that consumption of shark fins may increase the risk for human exposure to the cyanobacterial neurotoxin BMAA.

Mondo, Kiyo; Hammerschlag, Neil; Basile, Margaret; Pablo, John; Banack, Sandra A.; Mash, Deborah C.



Cyanobacterial Two-Component Proteins: Structure, Diversity, Distribution, and Evolution†  

PubMed Central

A survey of the already characterized and potential two-component protein sequences that exist in the nine complete and seven partially annotated cyanobacterial genome sequences available (as of May 2005) showed that the cyanobacteria possess a much larger repertoire of such proteins than most other bacteria. By analysis of the domain structure of the 1,171 potential histidine kinases, response regulators, and hybrid kinases, many various arrangements of about thirty different modules could be distinguished. The number of two-component proteins is related in part to genome size but also to the variety of physiological properties and ecophysiologies of the different strains. Groups of orthologues were defined, only a few of which have representatives with known physiological functions. Based on comparisons with the proposed phylogenetic relationships between the strains, the orthology groups show that (i) a few genes, some of them clustered on the genome, have been conserved by all species, suggesting their very ancient origin and an essential role for the corresponding proteins, and (ii) duplications, fusions, gene losses, insertions, and deletions, as well as domain shuffling, occurred during evolution, leading to the extant repertoire. These mechanisms are put in perspective with the different genetic properties that cyanobacteria have to achieve genome plasticity. This review is designed to serve as a basis for orienting further research aimed at defining the most ancient regulatory mechanisms and understanding how evolution worked to select and keep the most appropriate systems for cyanobacteria to develop in the quite different environments that they have successfully colonized.

Ashby, Mark K.; Houmard, Jean



Investigations on cyanobacterial diversity in a shallow estuary (Southern Baltic Sea) including genes relevant to salinity resistance and iron starvation acclimation.  


The cyanobacterial diversity in the pelagic of a shallow estuary at the Southern Baltic Sea has been investigated by a combination of classical morphological data and a polymerase chain reaction (PCR)-based molecular approach. The aim of the study was to investigate possible changes in the composition of the cyanobacterial community along the salinity and nutrient gradients. For this purpose partial gene sequences of cyanobacterial 16S rDNA and of two functional genes (ggpS- salinity tolerance marker, isiA- iron starvation marker) were amplified and compared with total community DNA. Random distribution of ggpS genotypes along the salinity gradient suggests that synthesis of the osmolyte glucosylglycerol is not restricted to higher salinity sampling sites. Most of the isiA sequences formed a new homogenous cluster in a phylogenetic tree, which indicates that the indigenous cyanobacterial community comprises a group of unknown species. Minimum iron concentrations, which can activate isiA transcription in model cyanobacteria, occurred at a few sampling sites with high phytoplankton biomass and moderate salinity. Nevertheless, isiA expression could be detected at all sampling sites, which indicated restricted iron supply to cyanobacterial phytoplankton in summer. PMID:15008815

Geiss, Ulrike; Selig, Uwe; Schumann, Rhena; Steinbruch, Robert; Bastrop, Ralf; Hagemann, Martin; Schoor, Arne



Lipid biomarkers, pigments and cyanobacterial diversity of microbial mats across intertidal flats of the arid coast of the Arabian Gulf (Abu Dhabi, UAE).  


Variations in morphology, fatty acids, pigments and cyanobacterial community composition were studied in microbial mats across intertidal flats of the arid Arabian Gulf coast. These mats experience combined extreme conditions of salinity, temperature, UV radiation and desiccation depending on their tidal position. Different mat forms were observed depending on the topology of the coast and location. The mats contained 63 fatty acids in different proportions. The increased amounts of unsaturated fatty acids (12-39%) and the trans/cis ratio (0.6-1.6%) of the cyanobacterial fatty acid n-18:1omega9 in the higher tidal mats suggested an adaptation of the mat microorganisms to environmental stress. Chlorophyll a concentrations suggested lower cyanobacterial abundance in the higher than in the lower intertidal mats. Scytonemin concentrations were dependent on the increase in solar irradiation, salinity and desiccation. The mats showed richness in cyanobacterial species, with Microcoleus chthonoplastes and Lyngbya aestuarii morphotypes as the dominant cyanobacteria. Denaturing gradient gel electrophoresis patterns suggested shifts in the cyanobacterial community dependent on drainage efficiency and salinity from lower to higher tidal zones. We conclude that the topology of the coast and the variable extreme environmental conditions across the tidal flat determine the distribution of microbial mats as well as the presence or absence of different microorganisms. PMID:18637042

Abed, Raeid M M; Kohls, Katharina; Schoon, Raphaela; Scherf, Ann-Kathrin; Schacht, Marion; Palinska, Katarzyna A; Al-Hassani, Huda; Hamza, Waleed; Rullkötter, Jürgen; Golubic, Stjepko



Denaturing Gradient Gel Electrophoresis Used To Monitor the Enrichment Culture of Aerobic Chemoorganotrophic Bacteria from a Hot Spring Cyanobacterial Mat  

Microsoft Academic Search

Previous studies investigating microbial diversity in the Octopus Spring cyanobacterial mat community (Yellowstone National Park) have shown a discrepancy between bacterial populations observed by molecular retrieval and cultivation techniques. To investigate how selective enrichment culture techniques affect species composition, we used denaturing gradient gel electrophoresis (DGGE) separation of PCR-amplified 16S rRNA gene fragments to monitor the populations contained within enrichment




Micronucleus induction and chromosome loss in transformed human white cells indicate clastogenic and aneugenic action of the cyanobacterial toxin, cylindrospermopsin  

Microsoft Academic Search

Cylindrospermopsin (CYN) is a potent inhibitor of protein synthesis produced by a number of cyanobacterial species, the most common being Cylindrospermopsis raciborskii. CYN contains a uracil moiety attached to a sulphated guanidino moiety, suggesting that it may have carcinogenic activity. This report describes the use of the WIL2-NS lymphoblastoid cell-line in the well-validated cytokinesis-block micronucleus (CBMN) assay to test this

Andrew R Humpage; Michael Fenech; Philip Thomas; Ian R Falconer



Nomenclatural validation of the genetically revised cyanobacterial genus Dolichospermum (R alfs ex B o R net et f lahault ) comb. nova  

Microsoft Academic Search

The traditional cyanobacterial genus Anabaena is heterogeneous, as follows from the modern molecular evaluation. The cluster of planktic Anabaena-morphotypes with gas vesicles in cells must be separated as a unique generic entity from the typical benthic mat-forming species. In the present articles all planktic morphospecies are transferred into the new genus Dolichospermum in agreement with Botanical nomenclatoric rules. The name

Pirjo W acklin


Sedimented cyanobacterial detritus as a source of nutrient for submerged macrophytes (Vallisneria spiralis and Elodea nuttallii): An isotope labeling experiment using 15N  

Microsoft Academic Search

A tracer experiment using the nitrogen isotope 15N investigated the uptake and incorporation of nitrogen from sedimented cyanobacterial detritus by two species of submerged macrophytes, the native Vallisneria spiralis and the exotic Elodea nuttallii, in Lake Taihu (China). The cyanobacterium Microcystis was labeled with 15Nammonium and dried to produce detritus, which was injected into vegetated sediments and traced to establish

Leiyan Zhang; Kuanyi Li; Zhengwen Liu; Jack J. Middelburg



Hindcasting cyanobacterial communities in Lake Okaro with germination experiments and genetic analyses.  


Cyanobacterial blooms are becoming increasingly prevalent worldwide. Sparse historic phytoplankton records often result in uncertainty as to whether bloom-forming species have always been present and are proliferating in response to eutrophication or climate change, or if there has been a succession of new arrivals through recent history. This study evaluated the relative efficacies of germination experiments and automated rRNA intergenic spacer analysis (ARISA) assays in identifying cyanobacteria in a sediment core and thus reconstructing the historical composition of cyanobacterial communities. A core (360 mm in depth) was taken in the central, undisturbed basin of Lake Okaro, New Zealand, a lake with a rapid advance of eutrophication and increasing cyanobacteria populations. The core incorporated a tephra from an 1886 volcanic eruption that served to delineate recent sediment deposition. ARISA and germination experiments successfully detected akinete-forming nostocaleans in sediment dating 120 bp and showed little change in Nostocales species structure over this time scale. Species that had not previously been documented in the lake were identified including Aphanizomenon issatschenkoi, a potent anatoxin-a producer. The historic composition of Chrococcales and Oscillatoriales was more difficult to reconstruct, potentially due to the relatively rapid degradation of vegetative cells within sediment. PMID:19077032

Wood, Susanna A; Jentzsch, Katrin; Rueckert, Andreas; Hamilton, David P; Cary, S Craig



Degradation of cyanobacterial biosignatures by ionizing radiation.  


Primitive photosynthetic microorganisms, either dormant or dead, may remain today on the martian surface, akin to terrestrial cyanobacteria surviving endolithically in martian analog sites on Earth such as the Antarctic Dry Valleys and the Atacama Desert. Potential markers of martian photoautotrophs include the red edge of chlorophyll reflectance spectra or fluorescence emission from systems of light-harvesting pigments. Such biosignatures, however, would be modified and degraded by long-term exposure to ionizing radiation from the unshielded cosmic ray flux onto the martian surface. In this initial study into this issue, three analytical techniques--absorbance, reflectance, and fluorescence spectroscopy--were employed to determine the progression of the radiolytic destruction of cyanobacteria. The pattern of signal loss for chlorophyll reflection and fluorescence from several biomolecules is characterized and quantified after increasing exposures to ionizing gamma radiation. This allows estimation of the degradation rates of cyanobacterial biosignatures on the martian surface and the identification of promising detectable fluorescent break-down products. PMID:22149884

Dartnell, Lewis R; Storrie-Lombardi, Michael C; Mullineaux, Conrad W; Ruban, Alexander V; Wright, Gary; Griffiths, Andrew D; Muller, Jan-Peter; Ward, John M



Cytotoxicity screening for the cyanobacterial toxin cylindrospermopsin.  


The cell lines C3A, HepG2, NCI-87, HCT-8, HuTu-80, Caco-2, and Vero were screened for sensitivity to the cyanobacterial toxin cylindrospermopsin (CYN), with the aim of determining the most sensitive cells to be used in cytotoxicity tests. Cell lines were chosen to be representative of the organs targeted by the toxin; liver, kidney, intestine, and were expected to have different metabolic activities and uptake capabilities. Over the range of cell lines tested, IC(50) determinations at 24 h (MTT assay) ranged fourfold, from 1.5 muM for hepatocyte-derived cell lines (C3A IC(50) = 1.5 +/- 0.54; HepG2 IC(50) = 1.5 +/- 0.87) to 6.5 +/- 3.3 micro the colon-derived Caco-2 cell line. The cell-line sensitivity seemed to decrease in cell lines derived from progressively more distal regions of the gastrointestinal tract: gastric > duodenal > ileal > colonic. The greater sensitivity of the hepatic cell lines to CYN was also apparent in 7-d exposure studies, with low toxin concentrations exerting cytotoxic effects that were not seen in other cell lines. Short-term exposure of C3A cells to CYN (1-6 h) was shown to induce cytotoxicity at 24 h despite a washout and recovery incubation, demonstrating the protracted and apparently irreversible nature of CYN's toxic effects. PMID:19184750

Froscio, Suzanne M; Fanok, Stella; Humpage, Andrew R



Distribution and impacts of introduced freshwater fishes in Western Australia  

Microsoft Academic Search

This paper presents comprehensive distributional data, from over 1300 sites, on introduced freshwater fishes in Western Australia. Currently, there are 10 species of introduced freshwater fish established in the inland waters of Western Australia. Most of the introduced fishes found here are those that have formed feral populations elsewhere in the world, and include members of the Salmonidae, i.e., rainbow

David L. Morgan; Howard S. Gill; Mark G. Maddern; Stephen J. Beatty



Nonindigenous Crayfishes Threaten North American Freshwater Biodiversity: Lessons from Europe  

Microsoft Academic Search

North America harbors about 390 native species of crayfishes, 75% of the world's total. In this article, we highlight the threats posed by nonindigenous crayfishes to freshwater ecosystem function, fisheries, and the biodiversity of native crayfishes; draw some lessons for North American freshwater conservation from the experience with nonindigenous crayfishes in Europe; and review existing regulations that address the introduction

David M. Lodge; Christopher A. Taylor; David M. Holdich; Jostein Skurdal



Persistent Organochlorine Residues in Marine and Freshwater Fish in Cambodia  

Microsoft Academic Search

Concentrations of persistent organochlorines (OCs) such as PCBs (polychlorinated biphenyls), DDT compounds (DDTs), HCH (hexachlorocyclohexanes) isomers (HCHs), chlordane compounds (CHLs) and HCB (hexachlorobenzene) were determined in 27 species of marine and freshwater fish collected from Cambodia. DDT and its derivatives were the predominantly detected compounds in both marine and freshwater fish. PCBs were the second highest followed by HCHs, CHLs

Haruhiko Nakata; Shinsuke Tanabe; Touch Seang Tana



Origins of a cyanobacterial 6-phosphogluconate dehydrogenase in plastid-lacking eukaryotes  

Microsoft Academic Search

BACKGROUND: Plastids have inherited their own genomes from a single cyanobacterial ancestor, but the majority of cyanobacterial genes, once retained in the ancestral plastid genome, have been lost or transferred into the eukaryotic host nuclear genome via endosymbiotic gene transfer. Although previous studies showed that cyanobacterial gnd genes, which encode 6-phosphogluconate dehydrogenase, are present in several plastid-lacking protists as well

Shinichiro Maruyama; Kazuharu Misawa; Mineo Iseki; Masakatsu Watanabe; Hisayoshi Nozaki



Cyanobacterial Diversity and a New Acaryochloris-Like Symbiont from Bahamian Sea-Squirts  

PubMed Central

Symbiotic interactions between ascidians (sea-squirts) and microbes are poorly understood. Here we characterized the cyanobacteria in the tissues of 8 distinct didemnid taxa from shallow-water marine habitats in the Bahamas Islands by sequencing a fragment of the cyanobacterial 16S rRNA gene and the entire 16S–23S rRNA internal transcribed spacer region (ITS) and by examining symbiont morphology with transmission electron (TEM) and confocal microscopy (CM). As described previously for other species, Trididemnum spp. mostly contained symbionts associated with the Prochloron-Synechocystis group. However, sequence analysis of the symbionts in Lissoclinum revealed two unique clades. The first contained a novel cyanobacterial clade, while the second clade was closely associated with Acaryochloris marina. CM revealed the presence of chlorophyll d (chl d) and phycobiliproteins (PBPs) within these symbiont cells, as is characteristic of Acaryochloris species. The presence of symbionts was also observed by TEM inside the tunic of both the adult and larvae of L. fragile, indicating vertical transmission to progeny. Based on molecular phylogenetic and microscopic analyses, Candidatus Acaryochloris bahamiensis nov. sp. is proposed for this symbiotic cyanobacterium. Our results support the hypothesis that photosymbiont communities in ascidians are structured by host phylogeny, but in some cases, also by sampling location.

Lopez-Legentil, Susanna; Song, Bongkeun; Bosch, Manel; Pawlik, Joseph R.; Turon, Xavier



Cyanobacterial blooms and the presence of cyanotoxins in small high altitude tropical headwater reservoirs in Kenya.  


The phytoplankton community in three small (0.065-0.249 km2) reservoirs in the stepped plateau landscape in the Kinangop area above the Rift Valley floor in Kenya were studied between 1998 and 2000. Approximately 70 species of phytoplankton were identified. The community was dominated by chlorophytes, cyanobacteria and chrysophytes. Diatoms were rare. The phytoplankton assemblage was frequently dominated by cyanobacteria in the dry season. The phytoplankton assemblage transformed to a mixture of cyanobacteria, chlorophytes and chrysophytes at the onset of the long rains, and mixture of cyanobacteria and chlorophytes after the long rains. Thereafter the phytoplankton assemblage consisted mainly of a mix of cyanobacteria and chrysophytes until the onset of the short rains when cyanobacterial dominance re-emerged. The most common phytoplankton species included Microcystis spp., Botryococcus braunii, Ceratium hirundinella, Anabaena spp. and Euglena viridis. The dry season cyanobacterial blooms produced cyanotoxins that included microcystin and endotoxins. The concentrations were well above the recommended safe limits for drinking water. The patterns of cyanotoxin production showed that the growth of the toxin-producing cyanobacteria was regulated by water temperature, pH and nutrients. The appearance of cyanotoxins in the small reservoirs is a serious public health issue in rural Kenya because such reservoirs are key sources of water for humans, livestock and wildlife. PMID:15384729

Mwaura, Francis; Koyo, Anderson O; Zech, Ben



Monitoring Biological Invasions in Freshwater Habitats  

Microsoft Academic Search

\\u000a Alien species invading freshwater systems are causing major changes in biodiversity worldwide. Some alien species have been\\u000a used as indicators of water quality and environmental degradation. We discuss the reasons for monitoring invasive species\\u000a beyond their use as ecological indicators, and offer guidance on the design of appropriate long-term monitoring schemes. Monitoring\\u000a plays an essential role in providing an early

Montserrat Vilà; Emili García-Berthou


Physiological responses of Xenopus laevis tadpoles exposed to cyanobacterial biomass containing microcystin-LR.  


Cyanobacteria are the primary biomass producers and some species synthesize remarkable amounts of secondary metabolites, the so-called cyanotoxins. Several reports deal with the most common cyanotoxins, microcystins (MCs), and their effects on fishes but only a few studies investigated a natural exposure to MCs and limited information is available concerning the further aquatic vertebrate class, amphibians. In the present study, Xenopus laevis tadpoles at stage 52 (Nieuwkoop and Faber, 1994) were exposed for 1, 3, 7, and 21 days to diets containing lyophilized cyanobacterial biomass without and with microcystin-LR (MC-LR) at concentrations of 42.8 and 187.0 ?g MC-LR/g diet, respectively, to determine impacts on MC-LR bioaccumulation, development, stress, and biotransformation. The fate of MC-LR present in diet and water was determined in whole body using liquid chromatography with tandem mass spectrometry detection. Effects on development were assessed by recording mortality, weight and developmental stage. In parallel, mRNA levels of hypophyseal thyroid stimulating hormone (TSH) associated with metamorphosis and of gonadotropins, luteinizing hormone and follicle stimulating hormone, triggering sexual differentiation, were assessed. Concerning stress, corticosteroid levels and mRNA expression of heat shock protein 70 (HSP70) as stress biomarkers were examined. Furthermore, mRNA expression of biotransformation enzymes of all three phases as well as biomarkers for oxidative stress were determined. Surprisingly, exposure to cyanobacterial biomass containing MC-LR supplied via diet as natural exposure neither resulted in measurable bioaccumulation of MC-LR nor affected dramatically development. Only minor to negligible physiological impacts on development, stress, and biotransformation mechanisms were found suggesting that X. laevis tadpoles seem to have some mechanisms to be able to cope quite well with diets containing lyophilized cyanobacterial biomass even with considerable amounts of MC-LR. PMID:23266398

Ziková, Andrea; Lorenz, Claudia; Lutz, Ilka; Pflugmacher, Stephan; Kloas, Werner



Microcystin accumulation and antioxidant responses in the freshwater clam Diplodon chilensis patagonicus upon subchronic exposure to toxic Microcystis aeruginosa.  


We investigated the accumulation and toxicity of microcystin-LR (MCLR) in the digestive gland of the freshwater clam Diplodon chilensis patagonicus. Treated clams were fed with a toxic strain of Microcystis aeruginosa (NPJB1) during 6 weeks and control clams received the non-toxic strain NPDC1. Filtration rate was estimated for both groups. Toxic effects were evaluated through the hepatosomatic index (HSI) and different oxidative stress biomarkers, lipid peroxidation (content of thiobarbituric reactive substances-TBARS), protein oxidation (carbonyl groups) and reduced glutathione (GSH) levels, and enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST). The extractable MCLR measured by ELISA in digestive gland extracts showed little or no change during the first 3 weeks and increased significantly at weeks 5 and 6. HSI was reduced by 30% in treated clams at weeks 5 and 6. No significant oxidative damage to lipids or proteins was. All the antioxidant defense parameters analyzed were significantly increased at week 5 or 6. GSH increased in treated clams at week 5, reaching 62% increase at week 6. SOD, CAT and GST activities were significantly increased in treated clams by 50%, 66% and 60%, respectively, at the end of the experiment. D. chilensis patagonicus can be exposed to prolonged cyanobacterial blooms accumulating significant quantities of MCLR, which could be a risk for mammals and birds, which feed on this species and, in a lesser extent, to humans. PMID:21477863

Sabatini, Sebastián E; Brena, Beatríz M; Luquet, Carlos M; San Julián, Magdalena; Pirez, Macarena; Carmen Ríos de Molina, María Del



Health Risk Assessment for Cyanobacterial Toxins in Seafood  

PubMed Central

Cyanobacteria (blue-green algae) are abundant in fresh, brackish and marine waters worldwide. When toxins produced by cyanobacteria are present in the aquatic environment, seafood harvested from these waters may present a health hazard to consumers. Toxicity hazards from seafood have been internationally recognised when the source is from marine algae (dinoflagellates and diatoms), but to date few risk assessments for cyanobacterial toxins in seafood have been presented. This paper estimates risk from seafood contaminated by cyanobacterial toxins, and provides guidelines for safe human consumption.

Mulvenna, Vanora; Dale, Katie; Priestly, Brian; Mueller, Utz; Humpage, Andrew; Shaw, Glen; Allinson, Graeme; Falconer, Ian



Health risk assessment for cyanobacterial toxins in seafood.  


Cyanobacteria (blue-green algae) are abundant in fresh, brackish and marine waters worldwide. When toxins produced by cyanobacteria are present in the aquatic environment, seafood harvested from these waters may present a health hazard to consumers. Toxicity hazards from seafood have been internationally recognised when the source is from marine algae (dinoflagellates and diatoms), but to date few risk assessments for cyanobacterial toxins in seafood have been presented. This paper estimates risk from seafood contaminated by cyanobacterial toxins, and provides guidelines for safe human consumption. PMID:22690165

Mulvenna, Vanora; Dale, Katie; Priestly, Brian; Mueller, Utz; Humpage, Andrew; Shaw, Glen; Allinson, Graeme; Falconer, Ian



Microbial Weathering of Peridotites by a Tropical Cyanobacterial Mat  

NASA Astrophysics Data System (ADS)

Nickeliferous tropical laterites represent more than 60 percent of the worlds Ni reserves and are believed to be the product of millions of years of weathering on ultramafic peridotite rocks in tropical regions. While both Cyanobacterial mats and microbial weathering processes are well characterized in general, these structures have never been implicated in ultramafic rock weathering. We used Au/Hg amalgam voltammetric microelectrodes to measure several important dissolved redox-active species (Fe (II), Mn (II), oxygen, peroxide, and organo-Fe/Mn complexes) in situ. Dissolved Fe II/III, phosphate, nitrite, nitrate and electrical conductivity, pH, & Eh were measured on site by spectrophotometry and combination electrodes, respectively. Mat, rock and water samples were compared using a suite of analytical techniques (XRD, SIMS, XPS, ICP-MS). Microbial community structure was determined using ESEM and 16S rDNA cloning. In order to further investigate the relative importance of peroxide and organic ligands (e.g. DFAM) on weathering, laboratory incubations, monitored by voltammetry, were also conducted. In situ voltammetric profiles revealed significant redox zonation and the presence of both organo-Mn (III/IV) and organo-Fe(III) complexes within the mat. Importantly, 50 ?M peroxide was detected within 15 mm of the atmosphere/mat interface. The mat was highly enriched in Ni and Mn compared to the substrate. XPS and dynamic SIMS characterization of the rock surface showed trace metal zonation within a weathering rind. Laboratory experiments demonstrated maximal dissolution of Ni and Mn from the substrate in the presence of both peroxide and DFAM. The high peroxide concentrations in the mat are likely produced via a photochemical reaction involving DOC. Microbial successions resulting in the accumulation of organic material allow the development of redox zonation. We propose a mechanism for enhanced weathering of serpentenized peridotites under microaerophilic conditions, by means of a combination of peroxide and bacterially produced organic ligands. This process may be important for the development of nickeliferous laterite deposits.

Fowle, D.; Crowe, S.; O'Neill, A.; Weisener, C.



A natural freshwater origin for two chlamydial species, Candidatus Piscichlamydia salmonis and Candidatus Clavochlamydia salmonicola, causing mixed infections in wild brown trout (Salmo trutta).  


Gill disease in salmonids is characterized by a multifactorial aetiology. Epitheliocystis of the gill lamellae caused by obligate intracellular bacteria of the order Chlamydiales is one known factor; however, their diversity has greatly complicated analyses to establish a causal relationship. In addition, tracing infections to a potential environmental source is currently impossible. In this study, we address these questions by investigating a wild brown trout (Salmo trutta) population from seven different sites within a Swiss river system. One age class of fish was followed over 18 months. Epitheliocystis occurred in a site-specific pattern, associated with peak water temperatures during summer months. No evidence of a persistent infection was found within the brown trout population, implying an as yet unknown environmental source. For the first time, we detected 'Candidatus Piscichlamydia salmonis' and 'Candidatus Clavochlamydia salmonicola' infections in the same salmonid population, including dual infections within the same fish. These organisms are strongly implicated in gill disease of caged Atlantic salmon in Norway and Ireland. The absence of aquaculture production within this river system and the distance from the sea, suggests a freshwater origin for both these bacteria and offers new possibilities to explore their ecology free from aquaculture influences. PMID:22176683

Schmidt-Posthaus, Heike; Polkinghorne, Adam; Nufer, Lisbeth; Schifferli, Andrea; Zimmermann, Dieter R; Segner, Helmut; Steiner, Pascale; Vaughan, Lloyd



Invasive species threat: parasite phylogenetics reveals patterns and processes of host-switching between non-native and native captive freshwater turtles.  


One of the major threats to biodiversity involves biological invasions with direct consequences on the stability of ecosystems. In this context, the role of parasites is not negligible as it may enhance the success of invaders. The red-eared slider, Trachemys scripta elegans, has been globally considered among the worst invasive species. Since its introduction through the pet trade, T. s. elegans is now widespread and represents a threat for indigenous species. Because T. s. elegans coexists with Emys orbicularis and Mauremys leprosa in Europe, it has been suggested it may compete with the native turtle species and transmit pathogens. We examined parasite transfer from American captive to the two native species that co-exist in artificial pools of a Turtle Farm in France. As model parasite species we used platyhelminth worms of the family Polystomatidae (Monogenea) because polystomes have been described from American turtles in their native range. Phylogenetic relationships among polystomes parasitizing chelonian host species that are geographically widespread show patterns of diversification more complex than expected. Using DNA barcoding to identify species from adult and/or polystome eggs, several cases of host switching from exotic to indigenous individuals were illustrated, corroborating that parasite transmission is important when considering the pet trade and in reintroduction programmes to reinforce wild populations of indigenous species. PMID:21767431

Verneau, O; Palacios, C; Platt, T; Alday, M; Billard, E; Allienne, J-F; Basso, C; DU Preez, L H



Influence of salinity on the rates of oxygen consumption in two species of freshwater fishes, Phoxinus erythrogaster (family Cyprinidae), and Fundulus catenatus (family Fundulidae)  

Microsoft Academic Search

A dye process in a textile plant in southern Kentucky (USA) produces large quantities of saline waste-water which eventually enter Lake Cumberland via a municipal sewage treatment plant on Lily Creek. The impact of hypersaline conditions on two fish species native to the Cumberland River drainage system, redbelly dace (Phoxinus erythrogaster) and northern studfish (Fundulus catenatus), was assessed. These species

Conrad Toepfer; Michael Barton



Description of two new species of the genus Thaparocleidus Jain, 1952 (Monogenea, Dactylogyridae) from freshwater fish in India: morphological and molecular phylogenetic evidence.  


The present paper describes the taxonomy of two new monogeneans, namely, Thaparocleidus longiphallus sp. n. and T. siloniansis sp. n., based on morphological, morphometric and molecular biological analysis, collected from the fish Wallago attu (Bloch & Schn.) and Silonia silondia (Ham.), respectively, at Meerut, UP, India. Genetic characterization of the two new species is based on sequence analyses of the rDNA 28S gene using neighbour-joining and maximum-parsimony techniques. These methods are congruent in depicting T. longiphallus sp. n. and T. siloniansis sp. n. as closely related species, but distinct from each other and forming a subclade with other species of the genus Thaparocleidus Jain, 1952. Secondary-structure models of the large subunit rDNA of the two species were also predicted using a combined comparative and thermodynamic approach. Molecular morphometric and phylogenetic relationships of the isolates of the Thaparocleidus species are discussed in detail. PMID:22449612

Chaudhary, A; Singh, H S



Nicotiana glauca engineered for the production of ketocarotenoids in flowers and leaves by expressing the cyanobacterial crtO ketolase gene  

Microsoft Academic Search

Nicotiana glauca is a tobacco species that forms flowers with carotenoid-pigmented petals, sepals, pistil, ovary and nectary tissue. The carotenoids\\u000a produced are lutein, ?-carotene as well as some violaxanthin and antheraxanthin. This tobacco species was genetically modified\\u000a for ketocarotenoid biosynthesis by transformation with a cyanobacterial crtO ketolase gene under the 35S CaMV promoter. In the transformants, ketocarotenoids were detected in

Changfu Zhu; Tanja Gerjets; Gerhard Sandmann



Vertical Distribution of Epibenthic Freshwater Cyanobacterial Synechococcus spp. Strains Depends on Their Ability for Photoprotection  

PubMed Central

Background Epibenthic cyanobacteria often grow in environments where the fluctuation of light intensity and quality is extreme and frequent. Different strategies have been developed to cope with this problem depending on the distribution of cyanobacteria in the water column. Principal Findings Here we provide an experimental proof that the light intensity plays an important role in the vertical distribution of seven, closely related, epibenthic Synechococcus spp. strains isolated from various water depths from the littoral zone of Lake Constance in Germany and cultivated under laboratory conditions. Pigment analysis revealed that the amount of chlorophyll a and total carotenoids decreased with the time of light stress exposure in three phycoerythrin-rich strains collected from 7.0 m water depth and remained low during the recovery phase. In contrast, a constant level of chlorophyll a and either constant or enhanced levels of carotenoids were assayed in phycocyanin-rich strains collected from 1.0 and 0.5 m water depths. Protein analysis revealed that while the amount of biliproteins remained constant in all strains during light stress and recovery, the amount of D1 protein from photosystem II reaction centre was strongly reduced under light stress conditions in strains from 7.0 m and 1.0 m water depth, but not in strains collected from 0.5 m depth. Conclusion Based on these data we propose that light intensity, in addition to light quality, is an important selective force in the vertical distribution of Synechococcus spp. strains, depending on their genetically fixed mechanisms for photoprotection.

Lohscheider, Jens N.; Strittmatter, Martina; Kupper, Hendrik; Adamska, Iwona



Distribution and Diversity of Natural Product Genes in Marine and Freshwater Cyanobacterial Cultures and Genomes  

Microsoft Academic Search

Natural products are a functionally diverse class of biochemically synthesized compounds, which include antibiotics, toxins, and siderophores. In this paper, we describe both the detection of natural product activities and the sequence identification of gene fragments from two molecular systems that have previously been implicated in natural product production, i.e., nonribosomal peptide synthetases (NRPSs) and modular polyketide synthases (PKSs), in

Ian M. Ehrenreich; John B. Waterbury; Eric A. Webb



The Toxicity of Phossy Water to Selected Freshwater Organisms.  

National Technical Information Service (NTIS)

Six species of freshwater organisms were exposed to the wastewater from a white phosphorus munitions filling facility, Pine Bluff Arsenal, Pine Bluff, Arkansas, in stated toxicity tests. Both fish (Gambusia affins and Lepomis macrohirus) and benthic macro...

J. G. Pearson P. F. Robinson E. S. Bender



Freshwater Cyanobacteria (Blue-Green Algae) Toxins: Isolation and Characterization.  

National Technical Information Service (NTIS)

Biotoxins of freshwater blue-green algae (cyanobacteria) are currently classed as being either hepatotoxic peptides or neurotoxic alkaloids. This study is concerned with the examination of toxins from the species Anabaena flos-aquae, Aphanizomenon flos-aq...

W. W. Carmichael



Toxicity of vanadium to different freshwater organisms  

SciTech Connect

The aim of this study is to determine the acute and subchronic toxicity of vanadium for various species of freshwater fish. The long-term toxicity and the effect of vanadium on the reproduction of Daphnia magna is also evaluated and compared with the toxicity of other metals.

Beusen, J.M.; Neven, B.



Tidal Freshwater Wetland Herbivory in Anacostia Park.  

National Technical Information Service (NTIS)

Herbivory has played a major role in dictating vegetation abundance and species composition at Kingman Marsh in Anacostia Park, Washington, D.C., since restoration of this tidal freshwater wetland was initiated in 2000. In June 2009 an herbivory study was...

C. C. Krafft J. S. Hatfield R. S. Hammerschlag



Nonindigenous Crayfishes Threaten North American Freshwater Biodiversity  

Microsoft Academic Search

North America harbors about 390 native species of crayfishes, 75% of the world's total. In this arti- cle, we highlight the threats posed by nonindigenous crayfishes to freshwater ecosystem function, fisheries, and the biodiversity of native crayfishes; draw some lessons for North American freshwa- ter conservation from the experience with nonindigenous crayfishes in Europe; and review existing regulations that address

David M. Lodge; Christopher A. Taylor; David M. Holdich; Jostein Skurdal




EPA Science Inventory

Our results indicate the invasibility of riparian plant communities is driven by a combination of factors that determine the success or failure of invasive species establishment—most notably hydrology and temperature. A major objec...


The loss of native biodiversity and continuing nonindigenous species introductions in freshwater, estuarine, and wetland communities of Pearl Harbor, Oahu, Hawaiian Islands  

Microsoft Academic Search

The benthic invertebrates and fishes of the estuarine, lower stream areas, and wetlands of Pearl Harbor were sampled from\\u000a 1997–1998 as a companion study to marine inventories conducted in Pearl Harbor. The first comprehensive assessment of the\\u000a area found that nonindigenous species comprise the dominant portion of the biota. A total of 191 aquatic species in 8 phyla\\u000a were identified

Ronald A. Englund



Taxonomic Resolution and Quantification of Freshwater Macroinvertebrate Samples from an Australian Dryland River: The Benefits and Costs of Using Species Abundance Data  

Microsoft Academic Search

In studies using macroinvertebrates as indicators for monitoring rivers and streams, species level identifications in comparison\\u000a with lower resolution identifications can have greater information content and result in more reliable site classifications\\u000a and better capacity to discriminate between sites, yet many such programmes identify specimens to the resolution of family\\u000a rather than species. This is often because it is cheaper

Jonathan C. Marshall; Alisha L. Steward; Bronwyn D. Harch



Transfer of a cyanobacterial neurotoxin within a temperate aquatic ecosystem suggests pathways for human exposure  

PubMed Central

?-methylamino-L-alanine (BMAA), a neurotoxic nonprotein amino acid produced by most cyanobacteria, has been proposed to be the causative agent of devastating neurodegenerative diseases on the island of Guam in the Pacific Ocean. Because cyanobacteria are widespread globally, we hypothesized that BMAA might occur and bioaccumulate in other ecosystems. Here we demonstrate, based on a recently developed extraction and HPLC-MS/MS method and long-term monitoring of BMAA in cyanobacterial populations of a temperate aquatic ecosystem (Baltic Sea, 2007–2008), that BMAA is biosynthesized by cyanobacterial genera dominating the massive surface blooms of this water body. BMAA also was found at higher concentrations in organisms of higher trophic levels that directly or indirectly feed on cyanobacteria, such as zooplankton and various vertebrates (fish) and invertebrates (mussels, oysters). Pelagic and benthic fish species used for human consumption were included. The highest BMAA levels were detected in the muscle and brain of bottom-dwelling fishes. The discovery of regular biosynthesis of the neurotoxin BMAA in a large temperate aquatic ecosystem combined with its possible transfer and bioaccumulation within major food webs, some ending in human consumption, is alarming and requires attention.

Jonasson, Sara; Eriksson, Johan; Berntzon, Lotta; Spacil, Zdenek; Ilag, Leopold L.; Ronnevi, Lars-Olof; Rasmussen, Ulla; Bergman, Birgitta



First report of the cyanobacterial toxin cylindrospermopsin in the shallow, eutrophic lakes of western Poland.  


Cyanobacterial dominance in eutrophic lakes causes water quality problems due to the production of toxins harmful to humans and animals, as well as a number of odorous compounds. Cylindrospermopsin (CYN) is a potent cytotoxic cyanobacterial metabolite involved in triggering illness in humans. The occurrence of CYN has been mostly associated with tropical and subtropical cyanobacteria. We analyzed CYN concentration and phytoplankton assemblages of three lakes located in western Poland during the summers of 2006 and 2007. CYN was detected in 46% of our samples using the HPLC and LC-MS/MS methods. CYN concentrations were in the range of 0.16-1.8 microg L(-1) and exceeded the drinking water guideline value of 1 microgL(-1) in two samples. This is the first report of CYN occurrence in this part of Europe and provides further evidence that this toxin is common not only in subtropical and tropical regions. The lakes were dominated by Planktothrix agardhii but the occurrence of the CYN investigated here might be associated with the invasive species Cylindrospermopsis raciborskii and/or native Aphanizomenon gracile. PMID:19084257

Kokoci?ski, Miko?aj; Dziga, Dariusz; Spoof, Lisa; Stefaniak, Karolina; Jurczak, Tomasz; Mankiewicz-Boczek, Joanna; Meriluoto, Jussi



Transfer of a cyanobacterial neurotoxin within a temperate aquatic ecosystem suggests pathways for human exposure.  


beta-methylamino-L-alanine (BMAA), a neurotoxic nonprotein amino acid produced by most cyanobacteria, has been proposed to be the causative agent of devastating neurodegenerative diseases on the island of Guam in the Pacific Ocean. Because cyanobacteria are widespread globally, we hypothesized that BMAA might occur and bioaccumulate in other ecosystems. Here we demonstrate, based on a recently developed extraction and HPLC-MS/MS method and long-term monitoring of BMAA in cyanobacterial populations of a temperate aquatic ecosystem (Baltic Sea, 2007-2008), that BMAA is biosynthesized by cyanobacterial genera dominating the massive surface blooms of this water body. BMAA also was found at higher concentrations in organisms of higher trophic levels that directly or indirectly feed on cyanobacteria, such as zooplankton and various vertebrates (fish) and invertebrates (mussels, oysters). Pelagic and benthic fish species used for human consumption were included. The highest BMAA levels were detected in the muscle and brain of bottom-dwelling fishes. The discovery of regular biosynthesis of the neurotoxin BMAA in a large temperate aquatic ecosystem combined with its possible transfer and bioaccumulation within major food webs, some ending in human consumption, is alarming and requires attention. PMID:20439734

Jonasson, Sara; Eriksson, Johan; Berntzon, Lotta; Spácil, Zdenek; Ilag, Leopold L; Ronnevi, Lars-Olof; Rasmussen, Ulla; Bergman, Birgitta



Methodological constraints in the molecular biodiversity study of a thermomineral spring cyanobacterial mat: a case study.  


The biodiversity of a specific cyanobacterial mat associated to a thermomineral spring from the Western Plain of Romania was investigated. Light and electron microscopy, together with molecular tools (denaturing gradient gel electrophoresis-DGGE, automated ribosomal intergenic spacer analysis-ARISA and amplified ribosomal DNA restriction analysis-ARDRA), based on 16S rDNA and 16S-23S internal transcribed spacer markers were used. Based on the partial 16S rRNA fragments sequenced, eight cyanobacterial taxons were identified, all belonging to the Oscillatoriales order, Phormidium and Leptolyngbya being dominant. A significant difference was observed, in comparison with the morphological approach. In certain conditions, DGGE can provide misleading information due to multiple melting domains in the same sequence, to multiple rrn operons in the same genome and due to unspecific hybridization among closely related sequences. This can lead to an overestimated species abundance which can cause incorrect description of the microbial community investigated. Additional techniques, such as ARISA and ARDRA, can improve the microbial biodiversity studies, thus providing optimal results. PMID:20665239

Coman, Cristian; Bica, Adriana; Drug?, Bogdan; Barbu-Tudoran, Lucian; Drago?, Nicolae



The Oligomeric State of c Rings from Cyanobacterial F-ATP Synthases Varies from 13 to 15?  

PubMed Central

We isolated the c rings of F-ATP synthases from eight cyanobacterial strains belonging to four different taxonomic classes (Chroococcales, Nostocales, Oscillatoriales, and Gloeobacteria). These c rings showed different mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), probably reflecting their molecular masses. This supposition was validated with the previously characterized c11, c14, and c15 rings, which migrated on SDS-PAGE in proportion to their molecular masses. Hence, the masses of the cyanobacterial c rings can conveniently be deduced from their electrophoretic mobilities and, together with the masses of the c monomers, allow the calculation of the c ring stoichiometries. The method is a simple and fast way to determine stoichiometries of SDS-stable c rings and hence a convenient means to unambiguously determine the ion-to-ATP ratio, a parameter reflecting the bioenergetic efficacy of F-ATP synthases. AFM imaging was used to prove the accuracy of the method and confirmed that the c ring of Synechococcus elongatus SAG 89.79 is a tridecameric oligomer. Despite the high conservation of the c-subunit sequences from cyanobacterial strains from various environmental groups, the stoichiometries of their c rings varied between c13 and c15. This systematic study of the c-ring stoichiometries suggests that variability of c-ring sizes might represent an adaptation of the individual cyanobacterial species to their particular environmental and physiological conditions. Furthermore, the two new examples of c15 rings underline once more that an F1/Fo symmetry mismatch is not an obligatory feature of all F-ATP synthases.

Pogoryelov, Denys; Reichen, Christian; Klyszejko, Adriana L.; Brunisholz, Rene; Muller, Daniel J.; Dimroth, Peter; Meier, Thomas



Degradation of Cyanobacterial Toxin, Microcystin LR, using Chemical Oxidants  

Microsoft Academic Search

Cyanobacterial toxins, microcystins, are very potent hepatotoxins and their occurrence has been reported all over the world. They could threaten human health when toxic Microcystis occurs in water supply reservoirs. In this study, the effects of several environmental factors on production and degradation of toxins produced by cyanobacteria in Lake Soyang have been studied. A new rapid quantification method of

Dongjin Pyo; Jisun Yoo



Cyanobacterial blooms in the Baltic — A source of halocarbons  

Microsoft Academic Search

During summer, cyanobacteria become highly dominant in the Baltic Sea, forming extensive blooms. It is well established that algae form volatile halogenated organic compounds, halocarbons, but it has only been suggested that cyanobacteria are capable of a similar production. During a cruise in the Baltic proper in 29–31 July 2004, the halocarbon formation from a cyanobacterial bloom was studied. Incubation

Anders Karlsson; Nicole Auer; Detlef Schulz-Bull; Katarina Abrahamsson



Monitoring Changing Toxigenicity of a Cyanobacterial Bloom by Molecular Methods  

PubMed Central

Cyanobacterial blooms are potential health hazards in water supply reservoirs. This paper reports analyses of a cyanobacterial bloom by use of PCR-based methods for direct detection and identification of strains present and determination of their toxigenicity. Serial samples from Malpas Dam, in the New England region of Australia, were analyzed during a prolonged, mixed cyanobacterial bloom in the summer of 2000 to 2001. Malpas Dam has been shown in the past to have toxic blooms of Microcystis aeruginosa that have caused liver damage in the human population drinking from this water supply reservoir. Cyanobacterial genera were detected at low cell numbers by PCR amplification of the phycocyanin intergenic spacer region between the genes for the ? and ? subunits. The potential for microcystin production was determined by PCR amplification of a gene in the microcystin biosynthesis pathway. The potential for saxitoxin production was determined by PCR amplification of a region of the 16S rRNA gene of Anabaena circinalis strains. Toxicity of samples was established by mouse bioassay and high-pressure liquid chromatography. We show that bloom components can be identified and monitored for toxigenicity by PCR more effectively than by other methods such as microscopy and mouse bioassay. We also show that toxigenic strains of Anabaena and Microcystis spp. occur at this site and that, over the course of the bloom, the cell types and toxicity changed. This work demonstrates that PCR detection of potential toxicity can enhance the management of a significant public health hazard.

Baker, Judith A.; Entsch, Barrie; Neilan, Brett A.; McKay, David B.




EPA Science Inventory

The National Center for Environmental Assessment has prepared the Toxicological Reviews of Cyanobacterial Toxins: Anatoxin-a, Cylindrospermopsin and Microcystins (LR, RR, YR and LA) as a series of dose-response assessments to support the health assessment of unregulated contamina...


Proteomics with a pinch of salt: A cyanobacterial perspective  

Microsoft Academic Search

Cyanobacteria are ancient life forms and have adapted to a variety of extreme environments, including high salinity. Biochemical, physiological and genetic studies have contributed to uncovering their underlying survival mechanisms, and as recent studies demonstrate, proteomics has the potential to increase our overall understanding further. To date, most salt-related cyanobacterial proteomic studies have utilised gel electrophoresis with the model organism

Jagroop Pandhal; Phillip C Wright; Catherine A Biggs



Reduction of cyanobacterial toxins through coprophagy in Mytilus edulis  

Microsoft Academic Search

An experiment was conducted to follow the fate of the cyanobacterial toxin, nodularin, produced by Nodularia spumigena through ingestion by Mytilus edulis and re-ingestion of faecal material (coprophagy). Mussels were fed with cultures of N. spumigena, and the faeces that were produced were fed to other mussels not previously exposed to N. spumigena. Concentrations of nodularin were measured in the

C. Svensen; E. Strogyloudi; C. Wexels Riser; J. Dahlmann; C. Legrand; P. Wassmann; E. Granéli; K. Pagou



Reduction of cyanobacterial toxins through coprophagy in Mytilus edulis  

Microsoft Academic Search

An experiment was conducted to follow the fate of the cyanobacterial toxin, nodularin, produced by Nodularia spumigena through ingestion by Mytilus edulis and re-ingestion of faecal material (coprophagy). Mussels were fed with cultures of N. spumigena, and the faeces that were produced were fed to other mussels not previously exposed to N. spumigena. Concentrations of nodularin were measured in the

C. Svensen; E. Strogyloudi; C. Wexels Riser


Removal of cyanobacterial toxins by sediment passage  

NASA Astrophysics Data System (ADS)

Cyanbacterial toxins ("Cyanotoxins") comprise a wide range of toxic substances produced by cyanobacteria ("blue-green algae"). Cyanobacteria occur in surface water word wide and can be found in high concentrations during so-called algal blooms when conditions are favourable (e.g. high nutrient levels, high temperatures). Some cyanobacteria produce hepato- or neurotoxins, of which the hepatotoxic microcystins are the most common in Germany. The WHO guideline value for drinking water was set at 1 ?g/L. However, maximum concentrations in surface water can reach 25 mg/L, so that a secure method for toxin elimination has to be found when this water is used as source water for drinking water production. In order to assess if cyanotoxins can be removed by sediment passage the German Federal Environmental Agency (UBA) conducted laboratory- and field scale experiments as well as observations on bank filtration field sites. Laboratory experiments (batch- and column experiments for adsorption and degradation parameters) were conducted in order to vary a multitude of experimental conditions. These experiments were followed by field scale experiments on the UBA's experimental field in Berlin. This plant offers the unique possibility to conduct experiments on the behaviour of various agents - such as harmful substances - during infiltration and bank filtration under well-defined conditions on a field scale, and without releasing these substances to the environment. Finally the development of microcystin concentrations was observed between infiltrating surface water and a drinking water well along a transsecte of observation wells. The results obtained show that infiltration and bank filtration normally seem to be secure treatment methods for source water contaminated by microcystins. However, elimination was shown to be difficult under the following circumstances: - dying cyanobacterial population due to insufficient light and / or nutrients, low temperatures or application of algizides (high amount of extracellular microcystins), - sandy material with low shares of clay and silt (little adsorption), - low temperatures (delayed biodegradation), - anoxic conditions (delayed biodegradation), - missing clogging layer or "schmutzdecke" (little bacteria), - no previous contact to microcystins (non adapted bacteria). It is therefore the aim of a new project financed by the KompetenzZentrum Wasser Berlin (KWB) to focus on these critical circumstances in order to find out how to optimise artificial recharge and bank filtration regarding microcystin elimination.

Gruetzmacher, G.; Boettcher, G.; Chorus, I.; Bartel, H.



Picobenthic cyanobacterial populations revealed by 16S rRNA-targeted in situ hybridization.  


We report on the morphological identification of a population of benthic cyanobacteria from microbial mats, known previously only from molecular analyses of field samples, based on the retrieval of environmental 16S rRNA sequences. We used in situ hybridization with horseradish peroxidase-labelled oligonucleotide probes designed to target the 16S rRNA of our unidentified population. Two probes were designed and checked for target binding ability and specificity using membrane hybridization against electroblotted bands from a denaturant gradient gel electrophoresis (DGGE) fingerprint of 16S rDNA gene fragments from the original cyanobacterial community. Under in situ hybridization, these probes bound specifically to extremely small, unicellular, colony-forming cyanobacteria, 0.75-1 microm in diameter, which were embedded in abundant mucilaginous investments. We propose the term picobenthos, by analogy with picoplankton, to describe those unicellular benthic microbes around or less than 1 microm in diameter. Although picoplanktonic cyanobacteria are abundant in ocean and freshwaters, picobenthic (<1 microm) unicellular cyanobacteria are not typically recognized as a major component of microbial mats. The small size and low levels of photopigment autofluorescence from these cells probably rendered them cryptic or indistinguishable from heterotrophic bacteria in routine microscopic observations. It is not known how widespread picobenthic cyanobacteria may be in other environments. PMID:12123473

Abed, Raeid M M; Schönhuber, Wilhelm; Amann, Rudolf; Garcia-Pichel, Ferran



Field methods in the study of toxic cyanobacterial blooms: results and insights from Lake Erie research.  


Sound field methodologies are an essential prerequisite in the development of a basic understanding of toxic cyanobacteria blooms. Sample collection, on-site processing, storage and transportation, and subsequent analysis and documentation are all critically dependent on a sound field program that allows the researcher to construct, with minimal uncertainty, linkages between bloom events and cyanotoxin production with the ecology of the studied system. Since 1999, we have collected samples in Lake Erie as part of the MELEE (Microbial Ecology of the Lake Erie Ecosystem) and MERHAB-LGL (Monitoring Event Responses for Harmful Algal Blooms in the Lower Great Lakes) research programs to develop appropriate tools and refine methods necessary to characterize the ecology of the reoccurring cyanobacterial blooms in the systems. Satellite imagery, large ship expeditions, classical and novel molecular tools have been combined to provide insight into both the cyanobacteria responsible for these events as well as into some of the environmental cues that may facilitate the formation of toxic blooms. This information, as well new directions in cyano-specific monitoring will be presented to highlight needs for field program monitoring and/or researching toxic freshwater cyanobacteria. PMID:18461781

Wilhelm, Steven W



Comparative toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin to seven freshwater fish species during early life-stage development  

SciTech Connect

The toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to fathead minnow (Pimephales promelas), channel catfish (Ictalurus punctatus), lake herring (Coregonus artedii), medaka (Oryzias latipes), white sucker (Catastomus commersoni), northern pike (Esox lucius), and zebrafish (Danio danio) were observed during early life-stage development after waterborne exposure of fertilized eggs. Species sensitivity based on TCDD-C{sub egg} (TCDD concentration in eggs) was determined by effects observed over a 32-d period for all species except lake herring in which a 100-d period was used. Signs of TCDD toxicity, including edema, hemorrhaging, and craniofacial malformations were essentially identical to those observed in salmonids following TCDD egg exposure and preceded or accompanied mortality most often during the period from hatch through swim-up. The no-observed-effect concentrations and lowest-observed-effect concentrations, based on significant decreases in survival and growth as compared to the controls, ranged from 175 and 270 pg/g for lake herring to 424 and 2,000 pg/g for zebrafish, respectively. Shapes of concentration-response curves, expressed as TCDD-C{sub egg} versus percent mortality, were similar for all species and were consistently steep suggesting that the mechanism of action of TCDD is the same among these species. The LC{sub egg}50s ranged from 539 pg/g for the fathead minnow to 2,610 pg/g for zebrafish. Comparisons of LC{sub egg}50s indicate that the tested species were approximately 8 to 38 times less sensitive to TCDD than lake trout, the most sensitive species evaluated to date. When LC{sub egg}50s are normalized to the fraction lipid in eggs (LC{sub egg,f}50s), the risk to early life stage survival for the species tested ranges from 16- to 180-fold less than for lake trout.

Elonen, G.E.; Spehar, R.L.; Holcombe, G.W.; Johnson, R.D.; Fernandez, J.D.; Erickson, R.J.; Tietge, J.E.; Cook, P.M. [Environmental Protection Agency, Duluth, MN (United States). Mid-Continent Ecology Div.



Inhibition of gap-junctional intercellular communication and activation of mitogen-activated protein kinases by cyanobacterial extracts--indications of novel tumor-promoting cyanotoxins?  


Toxicity and liver tumor promotion of cyanotoxins microcystins have been extensively studied. However, recent studies document that other metabolites present in the complex cyanobacterial water blooms may also have adverse health effects. In this study we used rat liver epithelial stem-like cells (WB-F344) to examine the effects of cyanobacterial extracts on two established markers of tumor promotion, inhibition of gap-junctional intercellular communication (GJIC) and activation of mitogen-activated protein kinases (MAPKs) - ERK1/2. Extracts of cyanobacteria (laboratory cultures of Microcystis aeruginosa and Aphanizomenon flos-aquae and water blooms dominated by these species) inhibited GJIC and activated MAPKs in a dose-dependent manner (effective concentrations ranging 0.5-5mgd.w./mL). Effects were independent of the microcystin content and the strongest responses were elicited by the extracts of Aphanizomenon sp. Neither pure microcystin-LR nor cylindrospermopsin inhibited GJIC or activated MAPKs. Modulations of GJIC and MAPKs appeared to be specific to cyanobacterial extracts since extracts from green alga Chlamydomonas reinhardtii, heterotrophic bacterium Klebsiella terrigena, and isolated bacterial lipopolysaccharides had no comparable effects. Our study provides the first evidence on the existence of unknown cyanobacterial toxic metabolites that affect in vitro biomarkers of tumor promotion, i.e. inhibition of GJIC and activation of MAPKs. PMID:19619572

Bláha, Lud?k; Babica, Pavel; Hilscherová, Klára; Upham, Brad L



Inhibition of gap-junctional intercellular communication and activation of mitogen-activated protein kinases by cyanobacterial extracts - indications of novel tumor promoting cyanotoxins?  

PubMed Central

Toxicity and liver tumor promotion of cyanotoxins microcystins have been extensively studied. However, recent studies document that other metabolites present in the complex cyanobacterial water blooms may also have adverse health effects. In this study we used rat liver epithelial stem-like cells (WB-F344) to examine the effects of cyanobacterial extracts on two established markers of tumor promotion, inhibition of gap-junctional intercellular communication (GJIC) and activation of mitogen-activated protein kinases (MAPKs) – ERK1/2. Extracts of cyanobacteria (laboratory cultures of Microcystis aeruginosa and Aphanizomenon flos-aquae and water blooms dominated by these species) inhibited GJIC and activated MAPKs in a dose-dependent manner (effective concentrations ranging 0.5 - 5 mg d.w./mL). Effects were independent of the microcystin content and the strongest responses were elicited by the extracts of Aphanizomenon sp. Neither pure microcystin-LR nor cylindrospermopsin inhibited GJIC or activated MAPKs. Modulations of GJIC and MAPKs appeared to be specific to cyanobacterial extracts since extracts from green alga Chlamydomonas reinhardtii, heterotrophic bacterium Klebsiella terrigena, and isolated bacterial lipopolysaccharides had no comparable effects. Our study provides the first evidence on the existence of unknown cyanobacterial toxic metabolites that affect in vitro biomarkers of tumor promotion, i.e. inhibition of GJIC and activation of MAPKs.

Blaha, Ludek; Babica, Pavel; Hilscherova, Klara; Upham, Brad L.



A methodological approach to measuring the oxygen consumption profile of six freshwater fish species: implications for determination of the standard metabolic rate  

Microsoft Academic Search

Procedures for the determination of standard metabolic rate (SMR) are variable and subjective in respirometry. We examined the oxygen consumption profile of six fish species (three salmonids and three cyprinids) in respirometry, and analysed the implications for the determination of SMR. In addition, we used data on Arctic charr (Salvelinus alpinus) and bleak (Alburnus alburnus) to define, how the length

Ari Voutilainen; Eila Seppänen; Hannu Huuskonen



A review of current knowledge on toxic benthic freshwater cyanobacteria - Ecology, toxin production and risk management.  


Benthic cyanobacteria are found globally in plethora of environments. Although they have received less attention than their planktonic freshwater counterparts, it is now well established that they produce toxins and reports of their involvement in animal poisonings have increased markedly during the last decade. Most of the known cyanotoxins have been identified from benthic cyanobacteria including: the hepatotoxic microcystins, nodularins and cylindrospermopsins, the neurotoxic saxitoxins, anatoxin-a and homoanatoxin-a and dermatotoxins, such as lyngbyatoxin. In most countries, observations of toxic benthic cyanobacteria are fragmented, descriptive and in response to animal toxicosis events. Only a limited number of long-term studies have aimed to understand why benthic proliferations occur, and/or how toxin production is regulated. These studies have shown that benthic cyanobacterial blooms are commonly a mixture of toxic and non-toxic genotypes and that toxin concentrations can be highly variable spatially and temporally. Physiochemical parameters responsible for benthic proliferation vary among habitat type with physical disturbance (e.g., flow regimes, wave action) and nutrients commonly identified as important. As climatic conditions change and anthropogenic pressures on waterways increase, it seems likely that the prevalence of blooms of benthic cyanobacteria will increase. In this article we review current knowledge on benthic cyanobacteria: ecology, toxin-producing species, variables that regulate toxin production and bloom formation, their impact on aquatic and terrestrial organisms and current monitoring and management strategies. We suggest research needs that will assist in filling knowledge gaps and ultimately allow more robust monitoring and management protocols to be developed. PMID:23891539

Catherine, Quiblier; Susanna, Wood; Isidora, Echenique-Subiabre; Mark, Heath; Aurélie, Villeneuve; Jean-François, Humbert



Large scale wetland restoration of an inland, freshwater river delta in southern Oregon and the response of two endangered fish species  

NASA Astrophysics Data System (ADS)

The mouth of the Williamson River historically flowed through ~2,200 hectares of contiguous emergent marsh wetlands that were bisected by the Williamson River and connected to Upper Klamath and Agency Lake at the headwaters of the Klamath River in southern Oregon. Beginning in the 1940’s, levees were built and the wetlands were drained and converted to cropland, and the Williamson River flowed directly to Upper Klamath Lake with no access to floodplain or delta wetlands. The wetlands historically provided habitat to endemic fish species, and acted as a nutrient sink for the Williamson River before flowing into Upper Klamath Lake. The Nature Conservancy and partners recently breached and degraded over 22 miles of levees, moved over 2 million cubic yards of material and reconnected 5500 acres of historic deltaic wetlands to the adjacent Upper Klamath and Agency Lakes and along 5.6 miles of the lower Williamson River. The goals of the restoration were to improve water quality in Upper Klamath Lake and provide habitat for Lost River and shortnose suckers, two federally listed, endemic species of fish inhabiting the lake. Two years of fisheries monitoring since restoration has shown that these two species utilize the restored riparian and wetland habitats. It appears that wetlands act to retain fish and also provide them with food and protection during this young life stage, enhancing fitness and survival of young suckers. Restoration is expected to improve early survival of suckers, leading to increased recruitment to adult spawning stages and contributing to the recovery of these species.

Hendrixson, H.; Stern, M. A.



The Amount of Space Available for Marine and Freshwater Fishes.  

National Technical Information Service (NTIS)

The author notes that 41.2% of all fish species live in less than one one-hundredth of one percent of the available water. Calculations show that there are about 11300 cu km of water per marine species but only about 15 cu km for each freshwater species, ...

M. H. Horn



Moluscos dulceacuícolas exóticos en Chile Exotic freshwater mollusks in Chile  

Microsoft Academic Search

The exotic freshwater mollusk species we report here were collected in wetlands, commercial aquariums, or were given to us by government offi cials who intercepted some exotic species at customs offi ces. Other records came from the specialized literature. These species are Pomacea bridgesii; Helobia sp.; Thiara (Melanoides) tuberculata; Melanoides maculata; Physa sp., Physella venustula and Biomphalaria sp. It is

Ana M. Ramos



Flow-induced Development of Unicellular Cyanobacterial Mats  

NASA Astrophysics Data System (ADS)

Microbial mats/biofilms are abundant microbial growth structures throughout the history of life on Earth. Understanding the mechanisms for their morphogenesis and interactions with physical sedimentary forces are important topics that allow deeper understanding of related records. When subjected to hydrodynamic influences, mats are known to vary in morphology and structure in response to fluid shear, yet mechanistically, the underlying cellular architecture due to interactions with flow remain unexplained. Moreover, mats are found to emerge larger scale roughness elements and modified cohesive strength growing under flow. It is a mystery how and why these mat-community-level features are linked in association with modified boundary layers at the mats surface. We examined unicellular cyanobacterium Synechocystis sp. PCC 6803 in a circular flow bioreactor designed to maintain a fixed set of hydrodynamic conditions. The use of monoculture strains and unidirectional currents, while not replicating natural mat systems (almost certainly multi-species and often multi-directional currents under complex wind or tidal wave actions), helps to simplify these systems and allows for specific testing of hypotheses regarding how mats evolve distinctive morphologies induced by flow. The unique design of the reactor also makes measurements such as critical erosional shear stress of the mats possible, in addition to microscopic, macroscopic imaging and weeks of continuous mats growth monitoring. We report the finding that linear chains, filament-like cell groups were present from unicellular cyanobacterial mats growing under flow (~1-5 cm/s) and these structures are organized within ~1-3mm size streamers and ~0.5-1mm size nodular macrostructures. Ultra-small, sub-micron thick EPS strings are observed under TEM and are likely the cohesive architectural elements in mats across different fluid regimes. Mat cohesion generally grows with and adapts to increasing flow shear stress within certain limits. Overall topological roughness of the mats were analyzed and estimated in terms of the skin friction of the mats surfaces interacting with flow. Then, together with the critical erosional cohesive strength of the mats estimated, we present a theoretical physical model linking morphology and material strength of mats to overlying fluid flow. If this model were further tested true, it suggests that physical flows may very well have a controlling effect on the properties of mats growing within it.

Gong, J.; Tice, M. M.



Identifying Canadian Freshwater Fishes through DNA Barcodes  

PubMed Central

Background DNA barcoding aims to provide an efficient method for species-level identifications using an array of species specific molecular tags derived from the 5? region of the mitochondrial cytochrome c oxidase I (COI) gene. The efficiency of the method hinges on the degree of sequence divergence among species and species-level identifications are relatively straightforward when the average genetic distance among individuals within a species does not exceed the average genetic distance between sister species. Fishes constitute a highly diverse group of vertebrates that exhibit deep phenotypic changes during development. In this context, the identification of fish species is challenging and DNA barcoding provide new perspectives in ecology and systematics of fishes. Here we examined the degree to which DNA barcoding discriminate freshwater fish species from the well-known Canadian fauna, which currently encompasses nearly 200 species, some which are of high economic value like salmons and sturgeons. Methodology/Principal Findings We bi-directionally sequenced the standard 652 bp “barcode” region of COI for 1360 individuals belonging to 190 of the 203 Canadian freshwater fish species (95%). Most species were represented by multiple individuals (7.6 on average), the majority of which were retained as voucher specimens. The average genetic distance was 27 fold higher between species than within species, as K2P distance estimates averaged 8.3% among congeners and only 0.3% among concpecifics. However, shared polymorphism between sister-species was detected in 15 species (8% of the cases). The distribution of K2P distance between individuals and species overlapped and identifications were only possible to species group using DNA barcodes in these cases. Conversely, deep hidden genetic divergence was revealed within two species, suggesting the presence of cryptic species. Conclusions/Significance The present study evidenced that freshwater fish species can be efficiently identified through the use of DNA barcoding, especially the species complex of small-sized species, and that the present COI library can be used for subsequent applications in ecology and systematics.

Hubert, Nicolas; Hanner, Robert; Holm, Erling; Mandrak, Nicholas E.; Taylor, Eric; Burridge, Mary; Watkinson, Douglas; Dumont, Pierre; Curry, Allen; Bentzen, Paul; Zhang, Junbin; April, Julien; Bernatchez, Louis



Evaluation of synergistic effects of bacterial and cyanobacterial strains as biofertilizers for wheat  

Microsoft Academic Search

An investigation was undertaken to screen, select and evaluate a set of bacterial and cyanobacterial isolates from the wheat\\u000a rhizosphere for their role as biofertilizers in wheat. From an initial set of 23 cyanobacterial strains and 110 bacterial\\u000a isolates from wheat rhizospheric soil, 3 bacterial and 3 cyanobacterial strains were selected based on their plant growth\\u000a promoting potential under laboratory

Lata Nain; Anuj Rana; Monica Joshi; Shrikrishna D. Jadhav; Dinesh Kumar; Y. S. Shivay; Sangeeta Paul; Radha Prasanna



Effects of living cyanobacteria, cyanobacterial extracts and pure microcystins on growth and ultrastructure of microalgae and bacteria.  


In this study, we demonstrate the inhibitory effect of both cyanobacterial extracts and pure microcystins on the growth of microalgae and bacteria. This inhibitory effect was more persistent in pure microcystins than in the extracts, which lost their properties eight days after exposure. In addition, the effects on bacteria were longerlasting than those on microalgae. The microalgae exposed to both extracts and cultures of microcystin producing species showed morphological and ultrastructural alterations, even in cases where there was no clear effect on growth. The implications for colonisation and benthic communities structure and development are discussed in the context of biomonitoring. PMID:17292433

Valdor, Rut; Aboal, Marina



Characterization of microcystin production in an Antarctic cyanobacterial mat community.  


Cyanobacteria are well known for their production of non-ribosomal cyclic peptide toxins, including microcystin, in temperate and tropical regions, however, the production of these compounds in extremely cold environments is still largely unexplored. Therefore, we investigated the production of protein phosphatase inhibiting microcystins by Antarctic cyanobacteria. We have identified microcystin-LR and for the first time [D-Asp3] microcystin-LR by mass spectrometric analysis in Antarctic cyanobacteria. The microcystins were extracted from a benthic microbial community that was sampled from a meltwater pond (Fresh Pond, McMurdo Ice Shelf, Antarctica). The extracted cyanobacterial cyclic peptides were equivalent to 11.4 ng MC-LR per mg dry weight by semi-quantitative analyses using HPLC-DAD and the protein phosphatase inhibition assay. Furthermore, we were able to identify the presence of cyanobacterial non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes in total DNA extracts from the mat community. PMID:16386280

Jungblut, Anne-Dorothee; Hoeger, Stefan J; Mountfort, Doug; Hitzfeld, Bettina C; Dietrich, Daniel R; Neilan, Brett A



Interannual variability of cyanobacterial blooms in Lake Erie.  


After a 20-year absence, severe cyanobacterial blooms have returned to Lake Erie in the last decade, in spite of negligible change in the annual load of total phosphorus (TP). Medium-spectral Resolution Imaging Spectrometer (MERIS) imagery was used to quantify intensity of the cyanobacterial bloom for each year from 2002 to 2011. The blooms peaked in August or later, yet correlate to discharge (Q) and TP loads only for March through June. The influence of the spring TP load appears to have started in the late 1990 s, after Dreissenid mussels colonized the lake, as hindcasts prior to 1998 are inconsistent with the observed blooms. The total spring Q or TP load appears sufficient to predict bloom magnitude, permitting a seasonal forecast prior to the start of the bloom. PMID:22870327

Stumpf, Richard P; Wynne, Timothy T; Baker, David B; Fahnenstiel, Gary L



Nodularin, a cyanobacterial toxin, is synthesized in planta by symbiotic Nostoc sp.  

PubMed Central

The nitrogen-fixing bacterium, Nostoc, is a commonly occurring cyanobacterium often found in symbiotic associations. We investigated the potential of cycad cyanobacterial endosymbionts to synthesize microcystin/nodularin. Endosymbiont DNA was screened for the aminotransferase domain of the toxin biosynthesis gene clusters. Five endosymbionts carrying the gene were screened for bioactivity. Extracts of two isolates inhibited protein phosphatase 2A and were further analyzed using electrospray ionization mass spectrometry (ESI-MS)/MS. Nostoc sp. ‘Macrozamia riedlei 65.1' and Nostoc sp. ‘Macrozamia serpentina 73.1' both contained nodularin. High performance liquid chromatography (HPLC) HESI-MS/MS analysis confirmed the presence of nodularin at 9.55±2.4?ng??g?1 chlorophyll a in Nostoc sp. ‘Macrozamia riedlei 65.1' and 12.5±8.4?ng??g?1 Chl a in Nostoc sp. ‘Macrozamia serpentina 73.1' extracts. Further scans indicated the presence of the rare isoform [L-Har2] nodularin, which contains ?-homoarginine instead of ?-arginine. Nodularin was also present at 1.34±0.74?ng?ml?1 (approximately 3?pmol per g plant ww) in the methanol root extracts of M. riedlei MZ65, while the presence of [L-Har2] nodularin in the roots of M. serpentina MZ73 was suggested by HPLC HESI-MS/MS analysis. The ndaA-B and ndaF genomic regions were sequenced to confirm the presence of the hybrid polyketide/non-ribosomal gene cluster. A seven amino-acid insertion into the NdaA-C1 domain of N. spumigena NSOR10 protein was observed in all endosymbiont-derived sequences, suggesting the transfer of the nda cluster from N. spumigena to terrestrial Nostoc species. This study demonstrates the synthesis of nodularin and [L-Har2] nodularin in a non-Nodularia species and the production of cyanobacterial hepatotoxin by a symbiont in planta.

Gehringer, Michelle M; Adler, Lewis; Roberts, Alexandra A; Moffitt, Michelle C; Mihali, Troco K; Mills, Toby J T; Fieker, Claus; Neilan, Brett A



Survey Techniques for Freshwater Streams on Oceanic Islands: Important Design Considerations for the PABITRA Project  

Microsoft Academic Search

Fundamental differences in life history patterns of most indigenous freshwater stream species on oceanic islands and freshwater species in continen- tal stream systems require important differences in design of appropriate aquatic survey methodologies. As an example of these issues, use of Instream Flow In- cremental Methodology (IFIM) and the Index of Biotic Integrity (IBI) for de- scribing island stream conditions

J. E. Parham



Diversity and biogeography of freshwater crabs (Crustacea: Brachyura: Potamidae, Gecarcinucidae) from East Asia  

Microsoft Academic Search

The diversity and biogeography of the two families of freshwater crabs in East Asia (China, Taiwan, Ryukyus and mainland Japan) were studied. The richness in different areas, as well as the distributions of all 40 genera and 311 species were analysed, the patterns examined and possible mechanisms discussed. The published data of freshwater crab species and their distributions in East





Microsoft Academic Search

Freshwater crayfish form a monophyletic group sister to clawed lobsters, and represent approximately 600 described species. These species are distributed on all continents except Antarctica with centres of diversity in the southeast United States and in Victoria, Australia. Taxonomically, the freshwater crayfish are grouped into two monophyletic super families representing the Northern Hemisphere Astacoidea and the southern hemisphere Parastacoidea. While





Technology Transfer Automated Retrieval System (TEKTRAN)

Despite the recent detection of caffeine in US streams, studies investigating caffeine's toxic effects on non-target freshwater organisms lack acute data for several standard surrogate species and chronic data for any freshwater species. The present study describes the mortality rate at different c...


Molecular Characterization of an Oil-Degrading Cyanobacterial Consortium  

Microsoft Academic Search

Recent studies have shown that the cyanobacterium Microcoleus chthonoplastes forms a consortium with heterotrophic bacteria present within the cyanobacterial sheath. These studies also show that this\\u000a consortium is able to grow in the presence of crude oil, degrading aliphatic heterocyclic organo-sulfur compounds as well\\u000a as alkylated monocyclic and polycyclic aromatic hydrocarbons. In this work, we characterize this oil-degrading consortium\\u000a through

Olga Sánchez; Elia Diestra; Isabel Esteve; Jordi Mas



Sample amount alternatives for data adjustment in comparative cyanobacterial metabolomics  

Microsoft Academic Search

Here we describe an integrative protocol for metabolite extraction and the measurement of three cellular constituents, chlorophyll\\u000a a, total protein, and glycogen from the same small volume of cyanobacterial cultures that can be used as alternative sample\\u000a amount parameters for data adjustment in comparative metabolome studies. We conducted recovery experiments to assess the robustness\\u000a and reproducibility of the measurements obtained

Jan Huege; Leonard Krall; Marie-Caroline Steinhauser; Patrick Giavalisco; Rosmarie Rippka; Nicole Tandeau de Marsac; Dirk Steinhauser



Classification trees as a tool for predicting cyanobacterial blooms  

Microsoft Academic Search

Nutrient enrichment of aquatic ecosystems caused dramatic increase in the frequency, magnitude and duration of cyanobacterial\\u000a blooms. Such blooms may cause fish kills, have adverse health effects on humans and contribute to the loss of biodiversity\\u000a in aquatic ecosystems. Some 50 eutrophic to hypereutrophic ponds from the Brussels Capital Region (Belgium) were studied between\\u000a 2003 and 2009. A number of

Anatoly Peretyatko; Samuel Teissier; Sylvia De Backer; Ludwig Triest


Molecular characterization of cyanobacterial diversity in Lake Gregory, Sri Lanka  

NASA Astrophysics Data System (ADS)

Eutrophication or the process of nutrient enrichment of stagnant waters due to excessive use of fertilizer is becoming a critical issue worldwide. Lake Gregory, an artificial lake situated in Nuwara Eliya, Sri Lanka was once a very attractive landscape feature and recreational area attracting a large number of visitors. Rapid urbanization in surrounding areas and the consequent intensification of agricultural and industrial activities led to eutrophication and siltation in the lake. Present study was conducted to detect cyanobacterial diversity and their ability to produce hepatotoxic microcystins using polymerase chain reaction (PCR)-based techniques. Twenty five water samples (surface and bottom) were collected from the lake and total nitrogen and total carbon were estimated. Cyanobacterial cultures were grown in appropriate media and microscopic observations were used to determine the morphological diversity of cyanobacteria isolated from different sites. Genomic DNA was isolated and purified from cyanobacteria using Boom's method. DNA samples were analyzed by PCR with oligonucleotide primers for 16S rRNA gene and mcyA gene of the operon that encodes a microcystin synthetase. The 16S rRNA gene sequences revealed the presences of cyanobacteria belong to Synechococcus sp., Microcystis aeruginosa, Calothrix sp., Leptolyngbya sp., Limnothrix sp., order Oscillatoriales and order Chroococcales. The sequences obtained from this study were deposited in the database under the accession numbers (GenBank: GU368104-GU368116). PCR amplification of mcyA primers indicated the potential for toxin formation of isolated M. aeruginosa from Lake Gregory. This preliminary study shows that the Lake Gregory is under the potential risk of cyanobacterial toxicity. Clearly more work is needed to extend this finding and clarify if other cyanobacterial isolates have genetic potential to produce microcystin since this lake is utilized for recreational activities.

Magana-Arachchi, Dhammika; Wanigatunge, Rasika; Liyanage, Madhushankha



Monitoring Survival and Preservation of Recent Cyanobacterial Mats  

NASA Astrophysics Data System (ADS)

Through geobiological evolution cyanobacterial mats have played a fundamental role through the development of early microbial carbonate ecosystems and through the sustainment of major biogeochemical cycling in the biosphere; nonetheless their sedimentary record is relatively modest in comparison with their biological impact; this apparent under-representation in the fossil record may be due to their intrinsic poor preservation potential but also to our inability to recognize some subtle microbial signatures. Modern studies on cyanobacterial mats involve high-tech molecular approaches to identify, analyze and even quantify the genetic diversity of ancient and modern microbial mats, yet the physical changes of mats, their survival and preservation potential, remain almost unknown and experimentally poorly explored. If we are going to succeed in the astrobiological quest for traces of life we should develop integrated methods and diagnostic features to address biosignatures at both, the phenotypic and genotypic levels when possible. The correct recognition and interpretation of biosignatures in this emerging field needs, aside these fine molecular tools, plain experimental approaches to test microbial resistance, survival and preservation potential of microbial mats after exposure to diagenetic changes. In this work we study some effects on fresh slices of cyanobacterial mats and cultures of specific external simulated agents that normally occur during diagenesis such as dehydratation, heat, abrasion or pressure among others. Samples from different cyanobacterial communities associated to carbonates collected from different rivers and falls around Mexico were subjected to same lab procedures. Physical and textural changes were monitored through microscopic analysis where cell integrity and mat cohesiveness were analyzed before and after treatment. Preliminary results show that mats enriched in halite and clay sediments were preferentially preserved; however those mats subjected to a rapid dehydration technique retained their original textural characteristics but their overall integrity was lost. Simple and direct observations like these help to get a better idea as to what to expect as biosignatures according to a specific environment, bridging the gap between the observer and the different types and scales of evidences.

Chacon, Elizabeth; Negron-Mendoza, Alicia; Camargo, Claudia



Cyanobacterial-based approaches to improving photosynthesis in plants.  


Plants rely on the Calvin-Benson (CB) cycle for CO(2) fixation. The key carboxylase of the CB cycle is ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). Efforts to enhance carbon fixation in plants have traditionally focused on RubisCO or on approaches that can help to remedy RubisCO's undesirable traits: its low catalytic efficiency and photorespiration. Towards reaching the goal of improving plant photosynthesis, cyanobacteria may be instrumental. Because of their evolutionary relationship to chloroplasts, they represent ideal model organisms for photosynthesis research. Furthermore, the molecular understanding of cyanobacterial carbon fixation provides a rich source of strategies that can be exploited for the bioengineering of chloroplasts. These strategies include the cyanobacterial carbon concentrating mechanism (CCM), which consists of active and passive transporter systems for inorganic carbon and a specialized organelle, the carboxysome. The carboxysome encapsulates RubisCO together with carbonic anhydrase in a protein shell, resulting in an elevated CO(2) concentration around RubisCO. Moreover, cyanobacteria differ from plants in the isoenzymes involved in the CB cycle and the photorespiratory pathways as well as in mechanisms that can affect the activity of RubisCO. In addition, newly available cyanobacterial genome sequence data from the CyanoGEBA project, which has more than doubled the amount of genomic information available for cyanobacteria, increases our knowledge on the CCM and the occurrence and distribution of genes of interest. PMID:23095996

Zarzycki, Jan; Axen, Seth D; Kinney, James N; Kerfeld, Cheryl A



Charismatic microfauna alter cyanobacterial production through a trophic cascade  

NASA Astrophysics Data System (ADS)

The trophic ecology of cyanobacterial blooms is poorly understood on coral reefs. Blooms of toxic cyanobacteria, Lyngbya majuscula, can quickly form large mats. The herbivorous sea hare, Stylocheilus striatus, and the predatory nudibranch, Gymnodoris ceylonica, often associate with these blooms, forming a linear food chain: nudibranch—sea hare—cyanobacteria. Using laboratory studies, this study quantified (1) the functional response of nudibranchs, (2) the effect of sea hare size on predation rates, and (3) the strength of the indirect effect of sea hare predation on cyanobacteria (i.e., a trophic cascade). Nudibranchs consumed on average 2.4 sea hares d-1, with the consumption of small sea hares 22 times greater than the consumption of large sea hares. Predation of sea hares reduced herbivory. Cyanobacterial biomass was 1.5 times greater when nudibranchs were present relative to when nudibranchs were absent. Although sea hare grazing can substantially reduce cyanobacterial biomass, predation of sea hares may mitigate grazing pressure, and therefore increase the abundance of cyanobacteria.

Geange, S. W.; Stier, A. C.



Late Devonian marine anoxia challenged by benthic cyanobacterial mats.  


Mass occurrence of benthic cyanobacterial mats in a sequence of Late Devonian black shales and bituminous limestones of the Holy Cross Mts. (central Poland), enclosing the famous Kellwasser and Hangenberg extinction horizons, is reported. The microbiota forming the mats is compared with some modern benthic chroococcalean cyanobacteria. Similarly to their extant counterparts, the Devonian cyanobacteria must had been phototrophic and oxygenic aerobes which could, however, tolerate slightly sulfidic conditions characterizing the near-bottom waters of the Late Devonian epicontinental sea. The cyanobacterial mats successfully colonized the oxygen-deficient and H(2)S-enriched seabed otherwise unfavorable for most other benthic biota. The redox state of this sluggish Late Devonian sea, ascribed previously mostly to anoxic or euxinic conditions, is reassessed as probably pulsating between anoxic, dysoxic, and weakly oxic conditions. The redox state was dependent on the rate of oxygen production by the cyanobacterial mats, the intensity of H(2)S emissions from the decaying mat biomass, and the rate of planktonic production. PMID:22882315

Kazmierczak, J; Kremer, B; Racki, G



Chlorophyll Fluorescence Analysis of Cyanobacterial Photosynthesis and Acclimation  

PubMed Central

Cyanobacteria are ecologically important photosynthetic prokaryotes that also serve as popular model organisms for studies of photosynthesis and gene regulation. Both molecular and ecological studies of cyanobacteria benefit from real-time information on photosynthesis and acclimation. Monitoring in vivo chlorophyll fluorescence can provide noninvasive measures of photosynthetic physiology in a wide range of cyanobacteria and cyanolichens and requires only small samples. Cyanobacterial fluorescence patterns are distinct from those of plants, because of key structural and functional properties of cyanobacteria. These include significant fluorescence emission from the light-harvesting phycobiliproteins; large and rapid changes in fluorescence yield (state transitions) which depend on metabolic and environmental conditions; and flexible, overlapping respiratory and photosynthetic electron transport chains. The fluorescence parameters FV/FM, FV?/FM?,qp,qN, NPQ, and ?PS II were originally developed to extract information from the fluorescence signals of higher plants. In this review, we consider how the special properties of cyanobacteria can be accommodated and used to extract biologically useful information from cyanobacterial in vivo chlorophyll fluorescence signals. We describe how the pattern of fluorescence yield versus light intensity can be used to predict the acclimated light level for a cyanobacterial population, giving information valuable for both laboratory and field studies of acclimation processes. The size of the change in fluorescence yield during dark-to-light transitions can provide information on respiration and the iron status of the cyanobacteria. Finally, fluorescence parameters can be used to estimate the electron transport rate at the acclimated growth light intensity.

Campbell, Douglas; Hurry, Vaughan; Clarke, Adrian K.; Gustafsson, Petter; Oquist, Gunnar



Cyanobacterial diversity and activity in modern conical microbialites.  


Modern conical microbialites are similar to some ancient conical stromatolites, but growth, behavior and diversity of cyanobacteria in modern conical microbialites remain poorly characterized. Here, we analyze the diversity of cyanobacterial 16S rRNA gene sequences in conical microbialites from 14 ponds fed by four thermal sources in Yellowstone National Park and compare cyanobacterial activity in the tips of cones and in the surrounding topographic lows (mats), respectively, by high-resolution mapping of labeled carbon. Cones and adjacent mats contain similar 16S rRNA gene sequences from genetically distinct clusters of filamentous, non-heterocystous cyanobacteria from Subsection III and unicellular cyanobacteria from Subsection I. These sequences vary among different ponds and between two sampling years, suggesting that coniform mats through time and space contain a number of cyanobacteria capable of vertical aggregation, filamentous cyanobacteria incapable of initiating cone formation and unicellular cyanobacteria. Unicellular cyanobacteria are more diverse in topographic lows, where some of these organisms respond to nutrient pulses more rapidly than thin filamentous cyanobacteria. The densest active cyanobacteria are found below the upper 50 ?m of the cone tip, whereas cyanobacterial cells in mats are less dense, and are more commonly degraded or encrusted by silica. These spatial differences in cellular activity and density within macroscopic coniform mats imply a strong role for diffusion limitation in the development and the persistence of the conical shape. Similar mechanisms may have controlled the growth, morphology and persistence of small coniform stromatolites in shallow, quiet environments throughout geologic history. PMID:22713108

Bosak, T; Liang, B; Wu, T-D; Templer, S P; Evans, A; Vali, H; Guerquin-Kern, J-L; Klepac-Ceraj, V; Sim, M S; Mui, J



Two new freshwater fish species of the genus Telestes (Actinopterygii, Cyprinidae) from karst poljes in Eastern Herzegovina and Dubrovnik littoral (Bosnia and Herzegovina and Croatia)  

PubMed Central

Abstract Two new species, Telestes dabar and Telestes miloradi, are described on the basis of morphological comparisons of isolated geographical populations of fishes identified earlier as Telestes metohiensis. A lectotype is designated for Telestes metohiensis, whose range is shown to include waters of Gata?ko, Cerni?ko, and Nevesinjsko poljes in Eastern Herzegovina. Telestes dabar from Dabarsko Polje (Eastern Herzegovina) and Telestes miloradi from Konavosko Polje (south Croatia) share with Telestes metohiensis the following combination of characters that distinguish them from the rest of the genus Telestes: pharyngeal teeth in one row, usually 5–4; preoperculo-mandibular canal not communicating with the infraorbital canal; mouth subterminal, the tip of the mouth cleft on or below the level of the ventral margin of the eye; postcleithrum minute or absent; ventral portion of the trunk with a dark stripe on a pale background; and dorsal portion of trunk uniformly dark and bordered ventrally by a dark midlateral stripe. Telestes dabar and Telestes miloradi are distinguishable from Telestes metohiensis in usually having 8½ branched dorsal-fin rays (vs. usually 7½), 9 or 10 gill rakers (vs. 7–10, usually 8), and the dark stripe on the ventral portion of the trunk below the main pigmented area of the back narrow and usually not reaching posteriorly to the caudal peduncle (vs. dark stripe wide and extending posteriorly to the caudal peduncle). Telestes dabar is distinguished from Telestes miloradi by having scales on most of the body situated close to one another and overlapping in a region behind the pectoral girdle and usually on the caudal peduncle (vs. overlapping scales on most of the body); the lateral line usually incomplete and interrupted, with 24–69, usually 54–65, total scales (vs. lateral line usually complete, with 55–67 total scales); scales above and below the lateral line slightly smaller than lateral-line scales (vs. of about equal size); head width 43–52% HL (vs. 48–58% HL); and lower jaw length 10–12% SL or 36–41% HL (vs. 8–10% SL or 33–38% HL). Telestes miloradi, a very local endemic species,is known only by historical samples. Telestes dabar is an abundant fish in Dabarsko Polje, but its range is critically restricted during the dry season by a few permanent sources. Nothing is known about its occurrence in underground karst waters.

Bogutskaya, Nina G.; Zupancic, Primoz; Bogut, Ivan; Naseka, Alexander M.



X-ray crystallographic studies on C-phycocyanins from cyanobacteria from different habitats: marine and freshwater  

PubMed Central

C-phycocyanins from three cyanobacterial cultures of freshwater and marine habitat, Spirulina, Phormidium and Lyngbya spp., were purified to homogeneity and crystallized using the hanging-drop vapour-diffusion method. Blue-coloured crystals in different crystal forms, monoclinic and hexagonal, were obtained for the three species. The crystals took 1–12 weeks to grow to full size using polyethylene glycols of different molecular weights as precipitants. The amino-acid sequences of these proteins show high similarity to other known C-­phycocyanins from related organisms; however, the C-­phycocyanins reported here showed different biochemical and biophysical properties, i.e. molecular weight, stability etc. The X-ray diffraction data were collected at resolutions of 3.0?Å for the monoclinic and 3.2 and 3.6?Å for the hexagonal forms. The unit-cell parameters corresponding to the monoclinic space group P21 are a = 107.33, b = 115.64, c = 183.26?Å, ? = 90.03° for Spirulina sp. C-­phycocyanin and are similar for crystals of Phormidium and Lyngbya spp. C-­phycocyanins. Crystals belonging to the hexagonal space group P63, with unit-cell parameters a = b = 154.97, c = 40.35?Å and a = b = 151.96, c = 39.06?Å, were also obtained for the C-phycocyanins from Spirulina and Lyngbya spp., respectively. The estimated solvent content is around 50% for the monoclinic crystals of all three species assuming the presence of two hexamers per asymmetric unit. The solvent content is 66.5 and 64.1% for the hexagonal crystals of C-phycocyanin from Spirulina and Lyngbya spp. assuming the presence of one ?? monomer per asymmetric unit.

Satyanarayana, L.; Suresh, C. G.; Patel, Anamika; Mishra, Sandhya; Ghosh, Pushpito Kumar



Restricted-Range Fishes and the Conservation of Brazilian Freshwaters  

PubMed Central

Background Freshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms) and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce. Methodology/Principal Findings Using data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29%) watersheds have lost more than 70% of their original vegetation cover, and only 141 (26%) show significant overlap with formally protected areas or indigenous lands. We detected 220 (40%) critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future. Conclusions/Significance We provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked drainage systems. Proper management (e. g. forestry code enforcement, landscape planning) and conservation (e. g. formal protection) of the 540 watersheds detected herein will be decisive in avoiding species extinction in the richest aquatic ecosystems on the planet.

Nogueira, Cristiano; Buckup, Paulo A.; Menezes, Naercio A.; Oyakawa, Osvaldo T.; Kasecker, Thais P.; Ramos Neto, Mario B.; da Silva, Jose Maria C.



Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium  

PubMed Central

Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these cyanobacteria. Results Deciphering the 5,172,804 bp sequence of Microcystis aeruginosa PCC 7806 has revealed the high plasticity of its genome: 11.7% DNA repeats containing more than 1,000 bases, 6.8% putative transposases and 21 putative restriction enzymes. Compared to the genomes of other cyanobacterial lineages, strain PCC 7806 contains a large number of atypical genes that may have been acquired by lateral transfers. Metabolic pathways, such as fermentation and a methionine salvage pathway, have been identified, as have genes for programmed cell death that may be related to the rapid disappearance of Microcystis blooms in nature. Analysis of the PCC 7806 genome also reveals striking novel biosynthetic features that might help to elucidate the ecological impact of secondary metabolites and lead to the discovery of novel metabolites for new biotechnological applications. M. aeruginosa and other large cyanobacterial genomes exhibit a rapid loss of synteny in contrast to other microbial genomes. Conclusion Microcystis aeruginosa PCC 7806 appears to have adopted an evolutionary strategy relying on unusual genome plasticity to adapt to eutrophic freshwater ecosystems, a property shared by another strain of M. aeruginosa (NIES-843). Comparisons of the genomes of PCC 7806 and other cyanobacterial strains indicate that a similar strategy may have also been used by the marine strain Crocosphaera watsonii WH8501 to adapt to other ecological niches, such as oligotrophic open oceans.

Frangeul, Lionel; Quillardet, Philippe; Castets, Anne-Marie; Humbert, Jean-Francois; Matthijs, Hans CP; Cortez, Diego; Tolonen, Andrew; Zhang, Cheng-Cai; Gribaldo, Simonetta; Kehr, Jan-Christoph; Zilliges, Yvonne; Ziemert, Nadine; Becker, Sven; Talla, Emmanuel; Latifi, Amel; Billault, Alain; Lepelletier, Anthony; Dittmann, Elke; Bouchier, Christiane; Tandeau de Marsac, Nicole



Kinetics of nitrate uptake by freshwater algae  

Microsoft Academic Search

The kinetics of nitrate (NO3-) uptake, the maximum uptake velocity (Vm) and the half-saturation constant (Ks), were determined for 18 species of batch-cultured freshwater algae grown without nitrogen limitation. Values of Ks ranged from 0.25 to 6.94 µM l-1Chlorella pyrenoidosa Chick, and Navicula pelliculosa (Breb.) Hilse, respectively. Values of Vm ranged from 0.51 to 5.07 µM l-1 h-1 for Anabaena

Steven G. Halterman; Dale W. Toetz



Cyanobacterial Responses to UV-Radiation  

Microsoft Academic Search

The influence of ultraviolet radiation (UVR) on microbial populations is the subject of intense investigation.One reason is\\u000a the awareness of how decreasing regional ozone levels in the stratosphere result in an increase of the UVB flux that reaches\\u000a the Earth’s surface. and the fact that microbial populations and species may show a more immediate and greater measurable\\u000a sensitivity to small

Richard Castenholz; Ferran Garcia-Pichel


Freshwater Marsh. Habitat Pac.  

ERIC Educational Resources Information Center

|The materials in this educational packet are designed for use with students in grades 4 through 7. They consist of an overview, three lesson plans and student data sheets, and a poster. The overview describes how the freshwater marsh is an important natural resource for plant, animal, and human populations and how the destruction of marshes…

Fish and Wildlife Service (Dept. of Interior), Washington, DC.


Biodiversity and seasonal variation of the cyanobacterial assemblage in a rice paddy field in Fujian, China  

Microsoft Academic Search

Cyanobacteria are one of the main components of the microbiota in rice paddy fields and significantly contribute to its fertilization. The diversity and changes of the cyanobacterial assemblage were investigated during a rice growth season and after harvest in a paddy field located in Fujian Province, China. The cyanobacterial populations were analyzed by a semi-nested PCR, followed by denaturing gradient

Tieying Song; Lotta Mårtensson; Torsten Eriksson; Weiwen Zheng; Ulla Rasmussen



Role of cyanobacteria in the biodegradation of crude oil by a tropical cyanobacterial mat  

Microsoft Academic Search

Cyanobacterial mats are ubiquitous in tropical petroleum-polluted environments. They form a high biodiversity microbial consortium that contains efficient hydrocarbons degraders. A cyanobacterial mat collected from a petroleum-contaminated environment located in Indonesia was studied for its biodegradation potential. In the field, the natural mat was shown to degrade efficiently the crude oil present in the environment. This natural mat demonstrated also

F. Chaillan; M. Gugger; A. Saliot; A. Couté; J. Oudot



Cyanobacterial contribution to the genomes of the plastid-lacking protists  

Microsoft Academic Search

BACKGROUND: Eukaryotic genes with cyanobacterial ancestry in plastid-lacking protists have been regarded as important evolutionary markers implicating the presence of plastids in the early evolution of eukaryotes. Although recent genomic surveys demonstrated the presence of cyanobacterial and algal ancestry genes in the genomes of plastid-lacking protists, comparative analyses on the origin and distribution of those genes are still limited. RESULTS:

Shinichiro Maruyama; Motomichi Matsuzaki; Kazuharu Misawa; Hisayoshi Nozaki



Hydrogen from Water in a Novel Recombinant Oxygen-Tolerant Cyanobacterial System (Presentation)  

SciTech Connect

The objective of this report is to develop an O{sub 2}-tolerant cyanobacterial system for continuous light-driven H{sub 2} production from water. The overall goal is to produce a cyanobacterial recombinant to produce H{sub 2} continuously.

Xu, Q.; Smith, H. O.; Maness, P.-C.



Accumulation of heavy metals in freshwater molluscs.  


Heavy metals in the aquatic environment have to date come mainly from naturally occurring geochemical materials. However, this has been enhanced by human activity such as gold mining in the case of heavy metal pollution in Sg Sarawak Kanan. The high suspended solid loads in the river have quite efficiently removed most soluble metals from the water and trapped them in the bottom sediment. Three freshwater mollusc species were collected at the point source of the heavy metal pollutants and analysed for the heavy metal contents in their tissues and shells. Two of the mollusc species (Brotia costula and Melanoides tuberculata) are purely freshwater species while the Clithon sp. nr retropictus is able to survive in fresh and brackish water environments. The Brotia costula and the Clithon sp. are the edible species which are sold in the market. Accumulation of As, Cu, Fe, Se and Zn in all the three mollusc species were determined and the level of As in the tissues of Brotia costula and the Clithon sp. was much higher than the permissible level for human consumption. The mollusc species also demonstrated different preferences for the uptake of different metals. Variations in the heavy metal contents in the shell and tissues of the same species were also observed. PMID:9646520

Lau, S; Mohamed, M; Yen, A T; Su'ut, S



A novel cyanophage with a cyanobacterial nonbleaching protein A gene in the genome.  


A cyanophage, PaV-LD, has been isolated from harmful filamentous cyanobacterium Planktothrix agardhii in Lake Donghu, a shallow freshwater lake in China. Here, we present the cyanophage's genomic organization and major structural proteins. The genome is a 95,299-bp-long, linear double-stranded DNA and contains 142 potential genes. BLAST searches revealed 29 proteins of known function in cyanophages, cyanobacteria, or bacteria. Thirteen major structural proteins ranging in size from 27 kDa to 172 kDa were identified by SDS-PAGE and mass-spectrometric analysis. The genome lacks major genes that are necessary to the tail structure, and the tailless PaV-LD has been confirmed by an electron microscopy comparison with other tail cyanophages and phages. Phylogenetic analysis of the major capsid proteins also reveals an independent branch of PaV-LD that is quite different from other known tail cyanophages and phages. Moreover, the unique genome carries a nonbleaching protein A (NblA) gene (open reading frame [ORF] 022L), which is present in all phycobilisome-containing organisms and mediates phycobilisome degradation. Western blot detection confirmed that 022L was expressed after PaV-LD infection in the host filamentous cyanobacterium. In addition, its appearance was companied by a significant decline of phycocyanobilin content and a color change of the cyanobacterial cells from blue-green to yellow-green. The biological function of PaV-LD nblA was further confirmed by expression in a model cyanobacterium via an integration platform, by spectroscopic analysis and electron microscopy observation. The data indicate that PaV-LD is an exceptional cyanophage of filamentous cyanobacteria, and this novel cyanophage will also provide us with a new vision of the cyanophage-host interactions. PMID:22031930

Gao, E-Bin; Gui, Jian-Fang; Zhang, Qi-Ya



Controlling harmful cyanobacterial blooms in a world experiencing anthropogenic and climatic-induced change.  


Harmful (toxic, food web altering, hypoxia generating) cyanobacterial algal blooms (CyanoHABs) are proliferating world-wide due to anthropogenic nutrient enrichment, and they represent a serious threat to the use and sustainability of our freshwater resources. Traditionally, phosphorus (P) input reductions have been prescribed to control CyanoHABs, because P limitation is widespread and some CyanoHABs can fix atmospheric nitrogen (N(2)) to satisfy their nitrogen (N) requirements. However, eutrophying systems are increasingly plagued with non N(2) fixing CyanoHABs that are N and P co-limited or even N limited. In many of these systems N loads are increasing faster than P loads. Therefore N and P input constraints are likely needed for long-term CyanoHAB control in such systems. Climatic changes, specifically warming, increased vertical stratification, salinization, and intensification of storms and droughts play additional, interactive roles in modulating CyanoHAB frequency, intensity, geographic distribution and duration. In addition to having to consider reductions in N and P inputs, water quality managers are in dire need of effective tools to break the synergy between nutrient loading and hydrologic regimes made more favorable for CyanoHABs by climate change. The more promising of these tools make affected waters less hospitable for CyanoHABs by 1) altering the hydrology to enhance vertical mixing and/or flushing and 2) decreasing nutrient fluxes from organic rich sediments by physically removing the sediments or capping sediments with clay. Effective future CyanoHAB management approaches must incorporate both N and P loading dynamics within the context of altered thermal and hydrologic regimes associated with climate change. PMID:21345482

Paerl, Hans W; Hall, Nathan S; Calandrino, Elizabeth S



Microcystins in Slovene freshwaters (central Europe)--first report.  


Cyanobacterial blooms are frequent in the North-Eastern region of Slovenia, where the agricultural activities are intensive, resulting in higher water eutrophication. In a two year monitoring program we identified eighteen blooms of cyanobacteria, fifteen being hepatotoxic by intraperitoneal mouse bioassay. The approximate LD100 varied from 50-1000 mg/kg (dry cell weight/animal weight) and gross pathological signs were characteristic of cyanobacterial hepatotoxins. Frequently the blooms were dominated by the most common and cosmopolitan species Microcystis aeruginosa. Other bloom forming species were M. wesenbergii, Oscillatoria rubescens, Anabaena flos-aquae, and Aphanizomenon flos-aquae. Using high-performance liquid chromatography (HPLC), three hepatotoxins were identified, microcystin RR being the most frequent and present in highest amounts, LR, and YR. The phytoplankton analysis revealed that several different species of cyanobacteria were present in the water bodies at the time of the blooms. Although present in various water bodies, filamentous bloom-forming cyanobacteria had no chance to proliferate in the presence of the colonial genus Microcystis. In individual cases we were faced with a bloom in the bloom, meaning that various Microcystis aeruginosa blooms were heavily contaminated with another cyanobacteria, Phormidium mucicola which infested the mucilage of the chroococcal species. PMID:9131592

Sedmak, B; Kosi, G




Microsoft Academic Search

We measured feeding preferences of the crayfish Procambarus clarkii for fresh tissue from four species of freshwater macrophytes (Haben- aria repens, Saururus cernuus, Ceratophyllum demersum and Typha angus- tifolia). We then determined the role of plant chemical defenses in generating these preferences by incorporating crude aqueous and organic extracts from each species into palatable foods and comparing feeding on these




Chemical Defenses of Freshwater Macrophytes Against Crayfish Herbivory  

Microsoft Academic Search

We measured feeding preferences of the crayfish Procambarus clarkii for fresh tissue from four species of freshwater macrophytes (Habenaria repens, Saururus cernuus, Ceratophyllum demersum and Typha angustifolia). We then determined the role of plant chemical defenses in generating these preferences by incorporating crude aqueous and organic extracts from each species into palatable foods and comparing feeding on these foods to

R. C. Bolser; M. E. Hay; N. Lindquist; William Fenical; Dean Wilson



Fish assemblages across a complex, tropical freshwater\\/marine ecotone  

Microsoft Academic Search

Riverine fish assemblages in the temperate zone generally show strong longitudinal patterns of faunal turnover and increases in species richness with increasing stream order. We examined the composition and structure of tropical fish assemblages across a complex freshwater\\/marine ecotone in Tortuguero National Park on the Caribbean coast of Central America. Species turnover was high between four characteristic habitats that largely

Kirk O. Winemiller; Mitchell A. Leslie



Freshwater sponges in Estonia: genetic and morphological identification  

Microsoft Academic Search

Samples of freshwater sponges (Porifera, Demospongiae, Haplosclerida, suborder Spongillina) were collected at three sites in South Estonia in the Sulaoja and Võhandu rivers. A molecular approach based on the sequencing of the extended D3 domain of the 28S rDNA was used for the confirmation of the identity of sponge species. The DNA analysis showed the presence of three spongillid species

Tiiu Rooverea; Annika Lopp; Tõnu Reintamm; Anne Kuusksalu; Evelyn Richelle-Maurer; Merike Kelve


Freshwater fishes, fisheries, and habitat prospects of Nepal  

Microsoft Academic Search

This paper deals with the status of fish, fisheries, and habitats in Nepal. Being a landlocked country, it has only freshwater habitats covering an area of 745,000 hectares (5% of the total area) that includes rivers, lakes, ponds, wetlands, reservoirs, and irrigated rice fields. It has a diverse fish species totaling 200 fish species, of which 191 are indigenous and

Chhatra M. Sharma



Global diversity of Isopod crustaceans (Crustacea; Isopoda) in freshwater  

Microsoft Academic Search

The isopod crustaceans are diverse both morphologically and in described species numbers. Nearly 950 described species (?9%\\u000a of all isopods) live in continental waters, and possibly 1,400 species remain undescribed. The high frequency of cryptic species\\u000a suggests that these figures are underestimates. Several major freshwater taxa have ancient biogeographic patterns dating from\\u000a the division of the continents into Laurasia (Asellidae,

George D. F. Wilson



Global diversity of Isopod crustaceans (Crustacea; Isopoda) in freshwater  

Microsoft Academic Search

The isopod crustaceans are diverse both morphologically and in described species numbers. Nearly 950 described species (~\\u000a 9% of all isopods) live in continental waters, and possibly 1,400 species remain undescribed. The high frequency of cryptic\\u000a species suggests that these figures are underestimates. Several major freshwater taxa have ancient biogeographic patterns\\u000a dating from the division of the continents into Laurasia

George D. F. Wilson


Cryptoendolithic lichen and cyanobacterial communities of the Ross Desert, Antarctica.  


Cryptoendolithic microbial communities in the Ross Desert (McMurdo Dry Valleys) are characterized on the basis of photosynthetic microorganisms and fungi. Two eukaryotic communities (the lichen-dominated and Hemichloris communities) and three cyanobacterial communities (the red Gloeocapsa, Hormathonema-Gloeocapsa, and Chroococcidiopsis communities) are described. Eleven coccoid, one pleurocapsoid, and five filamentous cyanobacteria occurring in these communities are characterized and illustrated. The moisture grade of the rock substrate seems to affect pH, formation of primary iron stain, and the distribution of microbial communities. PMID:11538357

Friedmann, E I; Hua, M; Ocampo-Friedmann, R



Freshwater Pollution and Treatment  

NSDL National Science Digital Library

This teaching resource was developed by a K-12 science teacher in the American Physiological SocietyÃÂs 2008 Frontiers in Physiology Program. For more information on this program, please visit This laboratory experiment teaches students the effects of pollutants on water quality and the impact it has on living organisms through fresh water quality testing of different environmental sources. Students should have some prior knowledge of the properties of water and a basic understanding of freshwater resources before beginning this activity. Upon completion of this activity, students will be able to: know how pollutants affect freshwater sources, interpret the most efficient tests to perform on water samples based on where the water originates, and analyze the affects pollutants have on water quality.

Michael Griffin (Brogden Middle School)



Ecology of tidal freshwater marshes of the United States east coast: a community profile  

SciTech Connect

Tidal freshwater marshes are a distinctive type of estuarine ecosystem located upstream from tidal saline marshes and downstream from non-tidal freshwater marshes. They are characterized by freshwater or nearly freshwater conditions most of the time, flora and fauna dominated by freshwater species, and daily lunar tidal flushing. This report examines the ecology of this community as it occurs along the Atlantic seaboard from southern New England to northern Florida. This marsh community is heavily influenced by river flow, which maintains freshwater conditions and deposits sediments high in silt and clay. The plant assemblage in tidal freshwater marshes is diverse both in numbers of species and structural plant types. Plant community structure is markedly diverse spatially and seasonally, and reflects the dynamic processing of energy and biomass in the marsh through high productivity, rapid decomposition and seasonal nutrient cycling. The diverse niches in this heterogeneous environment are exploited by a very diverse animal community of as many as 125 species of fish, 102 species of amphibians and reptiles, 280 species of birds, and 46 species of mammals over the community's broad range. Although fewer species are permanent residents or marsh breeders, use of his community for food and cover is high. This use, coupled with the marshes' capacity to be natural buffers and water filters, argue for their high value as natural resources. 349 references, 31 figures, 24 tables.

Odum, W.E.; Smith, T.J. III; Hoover, J.K.; McIvor, C.C.



Luminescence properties of a nanoporous freshwater diatom.  


Freshwater diatom frustules show special optical properties. In this paper we observed luminescence properties of the freshwater diatom Cyclotella meneghiniana. To confirm the morphological properties we present scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies were carried out to visualize the structural properties of the frustules, confirming that silica present in diatom frustules crystallizes in an ?-quartz structure. Study of the optical properties of the silica frustules of diatoms using ultra-violet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy confirmed that the diatom C. meneghiniana shows luminescence in the blue region of the electromagnetic spectrum when irradiated with UV light. This property of diatoms can be exploited to obtain many applications in day-to-day life. Also, using time-resolved photoluminescence spectroscopy (TRPL) it was confirmed that this species of diatom shows bi-exponential decay. PMID:21618682

Goswami, Bondita; Choudhury, Amarjyoti; Buragohain, Alak K



Improving the coverage of the cyanobacterial phylum using diversity-driven genome sequencing  

PubMed Central

The cyanobacterial phylum encompasses oxygenic photosynthetic prokaryotes of a great breadth of morphologies and ecologies; they play key roles in global carbon and nitrogen cycles. The chloroplasts of all photosynthetic eukaryotes can trace their ancestry to cyanobacteria. Cyanobacteria also attract considerable interest as platforms for “green” biotechnology and biofuels. To explore the molecular basis of their different phenotypes and biochemical capabilities, we sequenced the genomes of 54 phylogenetically and phenotypically diverse cyanobacterial strains. Comparison of cyanobacterial genomes reveals the molecular basis for many aspects of cyanobacterial ecophysiological diversity, as well as the convergence of complex morphologies without the acquisition of novel proteins. This phylum-wide study highlights the benefits of diversity-driven genome sequencing, identifying more than 21,000 cyanobacterial proteins with no detectable similarity to known proteins, and foregrounds the diversity of light-harvesting proteins and gene clusters for secondary metabolite biosynthesis. Additionally, our results provide insight into the distribution of genes of cyanobacterial origin in eukaryotic nuclear genomes. Moreover, this study doubles both the amount and the phylogenetic diversity of cyanobacterial genome sequence data. Given the exponentially growing number of sequenced genomes, this diversity-driven study demonstrates the perspective gained by comparing disparate yet related genomes in a phylum-wide context and the insights that are gained from it.

Shih, Patrick M.; Wu, Dongying; Latifi, Amel; Axen, Seth D.; Fewer, David P.; Talla, Emmanuel; Calteau, Alexandra; Cai, Fei; Tandeau de Marsac, Nicole; Rippka, Rosmarie; Herdman, Michael; Sivonen, Kaarina; Coursin, Therese; Laurent, Thierry; Goodwin, Lynne; Nolan, Matt; Davenport, Karen W.; Han, Cliff S.; Rubin, Edward M.; Eisen, Jonathan A.; Woyke, Tanja; Gugger, Muriel; Kerfeld, Cheryl A.



Cyanobacterial contribution to the genomes of the plastid-lacking protists  

PubMed Central

Background Eukaryotic genes with cyanobacterial ancestry in plastid-lacking protists have been regarded as important evolutionary markers implicating the presence of plastids in the early evolution of eukaryotes. Although recent genomic surveys demonstrated the presence of cyanobacterial and algal ancestry genes in the genomes of plastid-lacking protists, comparative analyses on the origin and distribution of those genes are still limited. Results We identified 12 gene families with cyanobacterial ancestry in the genomes of a taxonomically wide range of plastid-lacking eukaryotes (Phytophthora [Chromalveolata], Naegleria [Excavata], Dictyostelium [Amoebozoa], Saccharomyces and Monosiga [Opisthokonta]) using a novel phylogenetic pipeline. The eukaryotic gene clades with cyanobacterial ancestry were mostly composed of genes from bikonts (Archaeplastida, Chromalveolata, Rhizaria and Excavata). We failed to find genes with cyanobacterial ancestry in Saccharomyces and Dictyostelium, except for a photorespiratory enzyme conserved among fungi. Meanwhile, we found several Monosiga genes with cyanobacterial ancestry, which were unrelated to other Opisthokonta genes. Conclusion Our data demonstrate that a considerable number of genes with cyanobacterial ancestry have contributed to the genome composition of the plastid-lacking protists, especially bikonts. The origins of those genes might be due to lateral gene transfer events, or an ancient primary or secondary endosymbiosis before the diversification of bikonts. Our data also show that all genes identified in this study constitute multi-gene families with punctate distribution among eukaryotes, suggesting that the transferred genes could have survived through rounds of gene family expansion and differential reduction.



Improving the coverage of the cyanobacterial phylum using diversity-driven genome sequencing.  


The cyanobacterial phylum encompasses oxygenic photosynthetic prokaryotes of a great breadth of morphologies and ecologies; they play key roles in global carbon and nitrogen cycles. The chloroplasts of all photosynthetic eukaryotes can trace their ancestry to cyanobacteria. Cyanobacteria also attract considerable interest as platforms for "green" biotechnology and biofuels. To explore the molecular basis of their different phenotypes and biochemical capabilities, we sequenced the genomes of 54 phylogenetically and phenotypically diverse cyanobacterial strains. Comparison of cyanobacterial genomes reveals the molecular basis for many aspects of cyanobacterial ecophysiological diversity, as well as the convergence of complex morphologies without the acquisition of novel proteins. This phylum-wide study highlights the benefits of diversity-driven genome sequencing, identifying more than 21,000 cyanobacterial proteins with no detectable similarity to known proteins, and foregrounds the diversity of light-harvesting proteins and gene clusters for secondary metabolite biosynthesis. Additionally, our results provide insight into the distribution of genes of cyanobacterial origin in eukaryotic nuclear genomes. Moreover, this study doubles both the amount and the phylogenetic diversity of cyanobacterial genome sequence data. Given the exponentially growing number of sequenced genomes, this diversity-driven study demonstrates the perspective gained by comparing disparate yet related genomes in a phylum-wide context and the insights that are gained from it. PMID:23277585

Shih, Patrick M; Wu, Dongying; Latifi, Amel; Axen, Seth D; Fewer, David P; Talla, Emmanuel; Calteau, Alexandra; Cai, Fei; Tandeau de Marsac, Nicole; Rippka, Rosmarie; Herdman, Michael; Sivonen, Kaarina; Coursin, Therese; Laurent, Thierry; Goodwin, Lynne; Nolan, Matt; Davenport, Karen W; Han, Cliff S; Rubin, Edward M; Eisen, Jonathan A; Woyke, Tanja; Gugger, Muriel; Kerfeld, Cheryl A



Serum Electrolyte and Nonelectrolyte Status in Freshwater Juvenile Persian Sturgeon Acipenser persicus  

Microsoft Academic Search

Status of serum electrolyte and nonelectrolyte variables can be used for managing sturgeon species cultured in freshwater or living in seawater. The aim of the present study was to evaluate serum biochemical variables in clinically healthy juvenile Persian sturgeon Acipenser persicus cultured in freshwater. Serum samples from 11 females and 10 males were analyzed, and levels (mean ± SD) of

Farzad Asadi; Ali Hallajian; Ali Shahriari; Peyman Asadian; Malihe Pourkabir



Oceanic spawning ecology of freshwater eels in the western North Pacific  

Microsoft Academic Search

The natural reproductive ecology of freshwater eels remained a mystery even after some of their offshore spawning areas were discovered approximately 100 years ago. In this study, we investigate the spawning ecology of freshwater eels for the first time using collections of eggs, larvae and spawning-condition adults of two species in their shared spawning area in the Pacific. Ovaries of

Katsumi Tsukamoto; Seinen Chow; Tsuguo Otake; Hiroaki Kurogi; Noritaka Mochioka; Michael J. Miller; Jun Aoyama; Shingo Kimura; Shun Watanabe; Tatsuki Yoshinaga; Akira Shinoda; Mari Kuroki; Machiko Oya; Tomowo Watanabe; Kazuhiro Hata; Shigeho Ijiri; Yukinori Kazeto; Kazuharu Nomura; Hideki Tanaka



Toxin mixture in cyanobacterial blooms--a critical comparison of reality with current procedures employed in human health risk assessment.  


Cyanobacteria are the oldest life forms on earth known to produce a broad spectrum of secondary metabolites. The functions/advantages of most of these secondary metabolites (peptides and alkaloids) are unknown, however, some of them have adverse effects in humans and wildlife, especially when ingested, inhaled or upon dermal exposure. Surprisingly, some of these cyanobacteria are ingested voluntarily. Indeed, for centuries mankind has used cyanobacteria as a protein source, primarily Spirulina species. However, recently also Aphanizomenon flos-aquae are used for the production of so called blue green algae supplements (BGAS), supposedly efficacious for treatment of various diseases and afflictions. Unfortunately, traces of neurotoxins and protein phosphatases (inhibiting compounds) have been detected in BGAS, making these health supplements a good example for human exposure to a mixture of cyanobacterial toxins in a complex matrix. The discussion of this and other possible exposure scenarios, e.g. drinking water, contact during recreational activity, or consumption of contaminated food, can provide insight into the question of whether or not our current risk assessment schemes for cyanobacterial blooms and the toxins contained therein suffice for protection of human health. PMID:18461795

Dietrich, Daniel R; Fischer, A; Michel, C; Hoeger, S J



Effects of pollution on freshwater organisms  

SciTech Connect

This review includes subjects in last year's reviews on effects of pollution on freshwater invertebrates and effects of pollution on freshwater fish and amphibians. This review also includes information on the effects of pollution on freshwater plants. 625 references.

Phipps, G.L.; Harden, M.J.; Leonard, E.N.; Roush, T.H; Spehar, D.L.; Stephan, C.E.; Pickering, Q.H.; Buikema, A.L. Jr.



A series of experiments aimed at clarifying the mode of action of barley straw in cyanobacterial growth control.  


For over 25 years it has been known that rotting barley straw can be used to prevent the development of blooms of cyanobacteria and algae in freshwater bodies, although its effectiveness can be variable. The mode of action is still not understood, although a number of hypotheses have been suggested, many of which are supported by little or no experimental evidence. Here, we provide the first experimental confirmation that microbial activity is responsible for the release of either the growth inhibitory fraction, or its precursor, from whole straw, after three or more weeks of decomposition. However, a much more rapid release of inhibitory components was achieved by fine chopping of fresh straw. In bioassays of straw activity the choice of both the cyanobacterial test strain and the assay temperature affected the outcome. The inhibitory activity of straw was greater when decomposition was carried out in the presence of UV-supplemented visible light and this activity was reduced in the presence of catalase, implying that straw activity may in part involve hydrogen peroxide. A better understanding of straw decomposition is required to clarify the mode of action of straw and allow the optimisation of its use in the field. PMID:22989994

Iredale, Robert S; McDonald, Adrian T; Adams, David G



Double strand breaks and cell-cycle arrest induced by the cyanobacterial toxin cylindrospermopsin in HepG2 cells.  


The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the mechanisms of CYN toxicity and genotoxicity are not well understood. In the present study CYN induced formation of DNA double strand breaks (DSBs), after prolonged exposure (72 h), in human hepatoma cells, HepG2. CYN (0.1-0.5 µg/mL, 24-96 h) induced morphological changes and reduced cell viability in a dose and time dependent manner. No significant increase in lactate dehydrogenase (LDH) leakage could be observed after CYN exposure, indicating that the reduction in cell number was due to decreased cell proliferation and not due to cytotoxicity. This was confirmed by imunocytochemical analysis of the cell-proliferation marker Ki67. Analysis of the cell-cycle using flow-cytometry showed that CYN has an impact on the cell cycle, indicating G0/G1 arrest after 24 h and S-phase arrest after longer exposure (72 and 96 h). Our results provide new evidence that CYN is a direct acting genotoxin, causing DSBs, and these facts need to be considered in the human health risk assessment. PMID:23966038

Alja, Štraser; Filipi?, Metka; Novak, Matjaž; Žegura, Bojana



Double Strand Breaks and Cell-Cycle Arrest Induced by the Cyanobacterial Toxin Cylindrospermopsin in HepG2 Cells  

PubMed Central

The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the mechanisms of CYN toxicity and genotoxicity are not well understood. In the present study CYN induced formation of DNA double strand breaks (DSBs), after prolonged exposure (72 h), in human hepatoma cells, HepG2. CYN (0.1–0.5 µg/mL, 24–96 h) induced morphological changes and reduced cell viability in a dose and time dependent manner. No significant increase in lactate dehydrogenase (LDH) leakage could be observed after CYN exposure, indicating that the reduction in cell number was due to decreased cell proliferation and not due to cytotoxicity. This was confirmed by imunocytochemical analysis of the cell-proliferation marker Ki67. Analysis of the cell-cycle using flow-cytometry showed that CYN has an impact on the cell cycle, indicating G0/G1 arrest after 24 h and S-phase arrest after longer exposure (72 and 96 h). Our results provide new evidence that CYN is a direct acting genotoxin, causing DSBs, and these facts need to be considered in the human health risk assessment.

Straser, Alja; Filipic, Metka; Novak, Matjaz; Zegura, Bojana



Low levels of genetic differentiation among populations of the freshwater fish Hypseleotris compressa (Gobiidae: Eleotridinae): implications for its biology, population connectivity and history  

Microsoft Academic Search

The isolating nature of freshwater systems may lead to expectations of substantial genetic subdivision among populations of obligate freshwater species. We examined the genetic structure of populations of the freshwater fish Hypseleotris compressa (Gobiidae) using allozyme and mtDNA markers. Fifteen east coast Queensland populations and one Northern Territory population were sampled to examine levels of differentiation within and between drainages

Dugald J McGlashan; Jane M Hughes



Stream trees: a statistical method for mapping genetic differences between populations of freshwater organisms to the sections of streams that connect them  

Microsoft Academic Search

Statistical approaches for studying the spatial distribution of genetic diversity that assume that organisms move through a two-dimensional landscape are not well suited to study populations of freshwater fish. We present a new statisti- cal method for mapping genetic differences among populations of freshwater fish to the sections of streams that connect them. The method is useful for freshwater species

Steven T. Kalinowski; Michael H. Meeuwig; Shawn R. Narum; Mark L. Taper



Carassius gibelio in Greece: the dominant naturalised invader of freshwaters  

Microsoft Academic Search

Ichthyofauna in the Hellenic freshwaters is quite diverse consisted of 161 species (including 28 non-natives), out of the\\u000a 546 native species in Pan-European level. However, the status of many aquatic ecosystems is currently degraded as a result\\u000a of a variety of anthropogenic impacts. This has direct reflection on the conservation status of the indigenous and native\\u000a fish species whose populations

Costas Perdikaris; Anna Ergolavou; Evangelia Gouva; Cosmas Nathanailides; Athanasios Chantzaropoulos; Ioannis Paschos


Activated chemical defenses suppress herbivory on freshwater red algae.  


The rapid life cycles of freshwater algae are hypothesized to suppress selection for chemical defenses against herbivores, but this notion remains untested. Investigations of chemical defenses are rare for freshwater macrophytes and absent for freshwater red algae. We used crayfish to assess the palatability of five freshwater red algae relative to a palatable green alga and a chemically defended aquatic moss. We then assessed the roles of structural, nutritional, and chemical traits in reducing palatability. Both native and non-native crayfish preferred the green alga Cladophora glomerata to four of the five red algae. Batrachospermum helminthosum, Kumanoa holtonii, and Tuomeya americana employed activated chemical defenses that suppressed feeding by 30-60 % following damage to algal tissues. Paralemanea annulata was defended by its cartilaginous structure, while Boldia erythrosiphon was palatable. Activated defenses are thought to reduce ecological costs by expressing potent defenses only when actually needed; thus, activation might be favored in freshwater red algae whose short-lived gametophytes must grow and reproduce rapidly over a brief growing season. The frequency of activated chemical defenses found here (three of five species) is 3-20× higher than for surveys of marine algae or aquatic vascular plants. If typical for freshwater red algae, this suggests that (1) their chemical defenses may go undetected if chemical activation is not considered and (2) herbivory has been an important selective force in the evolution of freshwater Rhodophyta. Investigations of defenses in freshwater rhodophytes contribute to among-system comparisons and provide insights into the generality of plant-herbivore interactions and their evolution. PMID:23011851

Goodman, Keri M; Hay, Mark E



New data on freshwater psammic Gastrotricha from Brazil  

PubMed Central

Abstract Current knowledge of freshwater gastrotrich fauna from Brazil is underestimated as only two studies are available. The present communication is a taxonomic account of the first-ever survey of freshwater Gastrotricha in Minas Gerais State. Samplings were carried out yielding six species of three Chaetonotidae genera: Aspidiophorus cf. pleustonicus, Ichthydium cf. chaetiferum, Chaetonotus acanthocephalus, Chaetonotus heideri, Chaetonotus cf. succinctus, Chaetonotus sp., and also an undescribed species belonging to the genus Redudasys (incertae sedis): this is the first finding of specimens of Redudasys outside of original type locality. These preliminary observations suggest that the knowledge of the biodiversity of Gastrotricha in the Minas Gerais State, as well as in the whole Brazil, will certainly increase as further investigations are undertaken, and that freshwater Macrodasyida may be more common than previously thought.

Garraffoni, Andre R. S.; Araujo, Thiago Q.; Lourenco, Anete P.; Balsamo, Maria



United Nations Environment Programme: Freshwater  

NSDL National Science Digital Library

This portal provides access to information on equitable and sustainable management of freshwater resources around the world. Topics include water scarcity, irrigated agriculture, water and sanitation, water quality, groundwater, transboundary water management, water and ecosystems, floods and droughts, and urban water. There are also case studies, global assessments of freshwater resources, policy documents, and information on conferences and other events.


Feasting in fresh water: impacts of food concentration on freshwater tolerance and the evolution of food x salinity response during the expansion from saline into fresh water habitats  

PubMed Central

Saline to freshwater invasions have become increasingly common in recent years. A key hypothesis is that rates of freshwater invasions have been amplified in recent years by increased food concentration, yet this hypothesis has remained unexplored. We examined whether elevated food concentration could enhance freshwater tolerance, and whether this effect evolves following saline to freshwater invasions. We examined physiological response to salinity and food concentration in a 2 × 2 factorial design, using ancestral brackish and freshwater invading populations of the copepod Eurytemora affinis. We found that high food concentration significantly increases low-salinity tolerance. This effect was reduced in the freshwater population, indicating evolution following the freshwater invasion. Thus, ample food could enable freshwater invasions, allowing subsequent evolution of low-salinity tolerance even under food-poor conditions. We also compared effects of food concentration on freshwater survival between two brackish populations from the native range. Impacts of food concentration on freshwater survival differed between the brackish populations, suggesting variation in functional properties affecting their propensity to invade freshwater habitats. The key implication is that high food concentration could profoundly extend range expansions of brackishwater species into freshwater habitats, potentially allowing for condition-specific competition between saline invaders and resident freshwater species.

Lee, Carol Eunmi; Moss, Wynne E; Olson, Nora; Chau, Kevin Fongching; Chang, Yu-Mei; Johnson, Kelsey E



Interactions between a cyanobacterial bloom ( Microcystis) and the submerged aquatic plant Ceratophyllum oryzetorum Kom.  

NASA Astrophysics Data System (ADS)

In aquatic ecosystems, macrophytes and phytoplankton are main primary producers, in which macrophyte plays an important role in maintaining clear water state, while phytoplankton often dominates in turbid waterbodies. In the present study, the growth and photosynthetic activity of the submerged aquatic plant Ceratophyllum oryzetorum Kom. in different cell densities of cyanobacterial bloom are studied. The results show that the plant length and fresh mass of C. oryzetorum are promoted by low cyanobacterial cell densities. Medium and high cyanobacterial cell densities, on the contrary, act as inhibitory. Furthermore, the photosynthetic activity of C. oryzetorum is strongly inhibited by high cyanobacterial cell densities. To a certain extent, the growth of cyanobacteria is inhibited by C. oryzetorum, but no significant effect is found in this study.

Li, Dunhai; Li, Genbao; Chen, Wuxiong; Liu, Yongding



Degradation of cyanobacterial toxin, microcystin LR, using chemical oxidants.  


Cyanobacterial toxins, microcystins, are very potent hepatotoxins and their occurrence has been reported all over the world. They could threaten human health when toxic Microcystis occurs in water supply reservoirs. In this study, the effects of several environmental factors on production and degradation of toxins produced by cyanobacteria in Lake Soyang have been studied. A new rapid quantification method of microcystins, using fluorescence for a detection signal and a lateral-flow-type immunochromatography as a separation system, was used. Chlorine, potassium permanganate, and hydrogen peroxide were used as chemical oxidants for the degradation of microcystin LR. When chlorine was used, the efficiency of degradation was the highest. The degradation reaction took 40 minutes. PMID:18569370

Pyo, Dongjin; Yoo, Jisun



Cyanobacterial sulfide-quinone reductase: cloning and heterologous expression.  


The gene encoding sulfide-quinone reductase (SQR; E.C.1.8.5.'), the enzyme catalyzing the first step of anoxygenic photosynthesis in the filamentous cyanobacterium Oscillatoria limnetica, was cloned by use of amino acid sequences of tryptic peptides as well as sequences conserved in the Rhodobacter capsulatus SQR and in an open reading frame found in the genome of Aquifex aeolicus. SQR activity was also detected in the unicellular cyanobacterium Aphanothece halophytica following sulfide induction, with a V(max) of 180 micromol of plastoquinone-1 (PQ-1) reduced/mg of chlorophyll/h and apparent K(m) values of 20 and 40 microM for sulfide and quinone, respectively. Based on the conserved sequences, the gene encoding A. halophytica SQR was also cloned. The SQR polypeptides deduced from the two cyanobacterial genes consist of 436 amino acids for O. limnetica SQR and 437 amino acids for A. halophytica SQR and show 58% identity and 74% similarity. The calculated molecular mass is about 48 kDa for both proteins; the theoretical isoelectric points are 7.7 and 5.6 and the net charges at a neutral pH are 0 and -14 for O. limnetica SQR and A. halophytica SQR, respectively. A search of databases showed SQR homologs in the genomes of the cyanobacterium Anabaena PCC7120 as well as the chemolithotrophic bacteria Shewanella putrefaciens and Thiobacillus ferrooxidans. All SQR enzymes contain characteristic flavin adenine dinucleotide binding fingerprints. The cyanobacterial proteins were expressed in Escherichia coli under the control of the T7 promoter. Membranes isolated from E. coli cells expressing A. halophytica SQR performed sulfide-dependent PQ-1 reduction that was sensitive to the quinone analog inhibitor 2n-nonyl-4-hydroxyquinoline-N-oxide. The wide distribution of SQR genes emphasizes the important role of SQR in the sulfur cycle in nature. PMID:10852862

Bronstein, M; Schütz, M; Hauska, G; Padan, E; Shahak, Y



Investigating dissolved air flotation performance with cyanobacterial cells and filaments.  


Dissolved air flotation (DAF) performance with two different naturally occurring cyanobacterial morphologies was investigated with respect to the biomass removal efficiency, the toxin release to water and the coagulant demand by different water background natural organic matter (NOM). Coagulation (C)/Flocculation (F)/DAF bench-scale experiments (2 min coagulation at 380 s(-1) with polyaluminium chloride (0.5-4 mg/L Al(2)O(3), the dose depending on the water NOM content); 8 min flocculation at 70 s(-1); 8 min DAF with 5 bar relative pressure and 8% pressurised recycle) were performed with single cells of Microcystis aeruginosa and Planktothrix rubescens filaments spiked in synthetic waters with different NOM contents (hydrophobic vs. hydrophilic NOM; moderate (2-3 mgC/L) vs. moderate-high concentration (ca. 6 mgC/L)). For both morphologies, the results show no apparent cyanobacterial damage (since the water quality did not degrade in dissolved microcystins and the removal of intracellular microcystins matched the removal of chlorophyll a) and high biomass removal efficiencies (93-99% for cells and 92-98% for filaments) provided optimal coagulant dose for chlorophyll a removal was ensured. Charge neutralisation by the polyaluminium chloride was the main coagulation mechanism of the M. aeruginosa cells and most likely also of the P. rubescens filaments. The specific coagulant demand was severely affected by NOM hydrophobicity, hydrophobic NOM (with a specific UV(254nm) absorbance, SUVA, above 4 L/(m mgC)) requiring ca. the triple of hydrophilic NOM (SUVA below 3 L/(m mgC)), i.e. 0.7 vs. 0.2-0.3 mg Al(2)O(3)/mg DOC. PMID:20362317

Teixeira, Margarida Ribau; Sousa, Vânia; Rosa, Maria João



Analysis of Freshwater Mussels (Unionidae) in the Lower Ohio River at Two Beds Near Olmsted, Illinois: 1992 Studies.  

National Technical Information Service (NTIS)

A survey to assess community characteristics, density, population demography of dominant species, and the likelihood of finding endangered species of freshwater mussels (Unionidae) was conducted in the lower Ohio River near Olmsted, IL. Data will be used ...

B. S. Payne A. C. Miller D. Shafer



Hydrogen metabolism by decomposing cyanobacterial aggregates in Big Soda Lake, Nevada  

Microsoft Academic Search

Hydrogen production by incubated cyanobacterial epiphytes occurred only in the dark, was stimulated by CâHâ, and was inhibited by Oâ. Addition of NOâ⁻ inhibited dark, anaerobic Hâ production, whereas the addition of NHâ\\/sup +\\/ inhibited Nâ fixation (CâHâ reduction) but not dark Hâ production. Aerobically incubated cyanobacterial aggregates consumed Hâ, but light-incubated rates (3.6 mu mol of Hâ g-1 h-1)




Geosmin occurrence in riverine cyanobacterial mats: is it causing a significant health hazard?  

Microsoft Academic Search

Toxicity endpoints (nonspecific cytotoxicity, hepatotoxicity, neurotoxicity, immunotoxicity, and mutagenicity) were studied in cyanobacterial mats obtained from a shallow river. Some of the cyanobacterial mats tested were known to be non-geosmin producers, while others were geosmin-producers. No microcystin-like compounds were detected by HPLC in any of the biofilm samples. The mutagenicity and neurotoxicity of biofilm metabolites was negligible, and generally weak

L. Bláha; S. Sabater; P. Babica; E. Vilalta


Utilization of cyanobacterial biomass from water bloom for bioproduction of lactic acid  

Microsoft Academic Search

Cyanobacterial biomass obtained from water blooms was successfully utilized as a material for lactic acid production. The starch contained in the biomass could be converted to D- and L-lactic acid with 80–90% yield by Lactobacillus amylovorus, in a manner similar to that contained in laboratory-cultured cyanobacterial biomass. The starch was also available for L-lactic acid production with similar high yields

Susilaningsih Dwi; Kazumasa Hirata; Yasuo Asada; Kazuhisa Miyamoto



Plant-Mediated Phosphorus Mobilization from Sediments: Potential Influence on Freshwater Phosphorus Cycling.  

National Technical Information Service (NTIS)

The mobilization of sediment phosphorus (P) by three submersed freshwater pplant species was investigated on five different sediments. The study was conducted under controlled environmental conditions in lucite columns that enabled the separation of sedim...

J. W. Barko R. M. Smart M. S. Matthews D. G. Hardin



Potential for Biomagnification of Contaminants within Marine and Freshwater Food Webs.  

National Technical Information Service (NTIS)

This report reviews the literature on the biomagnification of toxic heavy metals and organic contaminants within marine and freshwater food webs and is limited to gill-breathing species. The toxic metals included arsenic, cadmium, copper, lead mercury (bo...

S. H. Kay



A salinity and sulfate manipulation of hypersaline microbial mats reveals stasis in the cyanobacterial community structure.  


The cyanobacterial community structure and composition of hypersaline mats were characterized in an experiment in which native salinity and sulfate levels were modified. Over the course of approximately 1 year, microbial mats collected from Guerrero Negro (Baja, California Sur, Mexico) were equilibrated to lowered salinity (to 35 p.p.t.) and lowered sulfate (below 1 mM) conditions. The structure and composition of the cyanobacterial community in the top 5 mm of these mats were examined using a multifaceted cultivation-independent molecular approach. Overall, the relative abundance of cyanobacteria-roughly 20% of the total bacterial community, as assayed with a PCR-based methodology-was not significantly affected by these manipulations. Furthermore, the mat cyanobacterial community was only modestly influenced by the dramatic changes in sulfate and salinity, and the dominant cyanobacteria were unaffected. Community composition analyses confirmed the dominant presence of the cosmopolitan cyanobacterium Microcoleus chthonoplastes, but also revealed the dominance of another Oscillatorian cyanobacterial group, also detected in other hypersaline microbial mats. Cyanobacterial populations increasing in relative abundance under the modified salinity and sulfate conditions were found to be most closely related to other hypersaline microbial mat organisms, suggesting that the development of these mats under native conditions precludes the development of organisms better suited to the less restrictive experimental conditions. These results also indicate that within a significant range of salinity and sulfate concentrations, the cyanobacterial community is remarkably stable. PMID:18288215

Green, Stefan J; Blackford, Cameron; Bucki, Patricia; Jahnke, Linda L; Prufert-Bebout, Lee



Early stages of biofilm succession in a lentic freshwater environment  

Microsoft Academic Search

Initial events of biofilms development and succession were studied in a freshwater environment at Kalpakkam, East Coast of India. Biofilms were developed by suspending Perspex (Plexiglass) panels for 15 days at bimonthly intervals from January 1996 to January 1997. Changes in biofilm thickness, biomass, algal density, chlorophyll a concentration and species composition were monitored. The biofilm thickness, biomass, algal density

R. Sekar; V. P. Venugopalan; K. Nandakumar; K. V. K. Nair; V. N. R. Rao



Recovery of freshwater marsh vegetation after a saltwater intrusion event  

Microsoft Academic Search

Greenhouse mesocosms of freshwater marsh vegetation were exposed to a simulated saltwater intrusion event followed by a recovery period during which water levels and interstitial water salinity were adjusted over a range of conditions. Virtually all above-ground vegetation, including the three dominant species, Sagittaria lancifolia L., Leersia oryzoides (L.) Swartz, and Panicum hemitomon Schultes, was killed by the initial saltwater

K. M. Flynn; K. L. McKee; I. A. Mendelssohn



Biological control and invading freshwater snails.A case study  

Microsoft Academic Search

Introductions of four species of freshwater snails occurred between 1972 and 1996 onto Guadeloupe Island. Two of them, Melanoides tuberculata and Marisa cornuarietis, were subsequently used as biological control agents against Biomphalaria glabrata, the snail intermediate host of intestinal schistosomiasis. In 1996, a general survey was carried out in 134 sites which had already been investigated in 1972. The total

Jean-Pierre Pointier; David Augustin



Effects of Severe Drought on Freshwater Mussel Assemblages  

Microsoft Academic Search

We examined changes in freshwater mussel abundance and species composition at eight sites in Alabama and Mississippi in response to a severe drought in 2000. Five small-stream sites in Bankhead National Forest were heavily impacted by drought; one site dried almost completely, and four sites experienced total or near cessation of flow but retained water in their channels to a

Wendell R. Haag; Melvin L. Warren Jr



Mites (Acarina: Astigmata) associated with adult freshwater leeches (Hirudinea: Erpobdellidae)  

Microsoft Academic Search

Two species of mites (Astigmata: Acarina) were found crawling on the integument of cultured Nephelopsis obscura, a common North American leech. This is the first record of an association between mites and adult annelids. Histiostoma anguillarum (Histiostomatidae), previously described as an associate of farmed freshwater eels, were recorded in densities of 1–17 mites per leech, while an undescribed member of

H. C. Proctor; H. M. Gray; B. M. Oconnor



Ship noise and cortisol secretion in European freshwater fishes  

Microsoft Academic Search

Underwater noise pollution is a growing problem in aquatic environments and as such may be a major source of stress for fish. In the present study, we addressed the effects of ship noise and continuous Gaussian noise on adrenal activity in three European freshwater species. Underwater ship noise recorded in the Danube River and two Austrian lakes was played back

Lidia Eva Wysocki; John P. Dittami; Friedrich Ladich



Extracellular fibril production by freshwater algae and cyanobacteria  

Microsoft Academic Search

In order to study the ability of freshwater algae and cyanobacteria to form extracellular fibrils, a screening test using ruthenium red (RR) staining was carried out on 28 species. Five of these were examined for growth and production of fibrillar material in culture media of different phosphate (P;) contents. RR-staining and uronic acid determinations at various stages of algal growth

Tatiana Strycek; Judy Acreman; Alison Kerry; Gary G. Leppard; Milan V. Nermut; Donn J. Kushner



Freshwater mollusc biodiversity and conservation in two stressed Mediterranean basins  

Microsoft Academic Search

This paper reviews the environmental factors that influence biodiversity of freshwater mollusc communities and conservation status of watercourses in two Mediterranean acid mine drainage-impacted basins of the southern Iberian Peninsula. We found 17 mollusc species: 14 gastropods (10 native and 4 introduced) and 3 bivalves. We found five distribution patterns: native headwater (Arganiella wolfi, Stagnicola palustris, Unio delphinus, Pisidium casertanum

Juan Carlos Pérez-Quintero



Intersex in feral marine and freshwater fish from northeastern Germany  

Microsoft Academic Search

A histopathological assessment of the gonad of male fish was performed as part of biological field studies carried out in coastal waters and small rivers in Mecklenburg-Western Pomerania, northeastern Germany. In the marine environment the eelpout (Zoarces viviparus) was selected as sentinel species. The three spined stickleback (Gasterosteus aculeatus) and perch (Perca fluviatilis) were chosen at freshwater locations. Histopathology of

Jens Gercken; Holmer Sordyl



A numerical classification of reproductive guilds of the freshwater fishes of south-eastern Australia and their application to river management  

Microsoft Academic Search

A comprehensive list of freshwater fishes from south-eastern Australia is classified into five major reproductive guilds, based on numerical analysis of 13 life history or reproductive characteristics. The guilds defined generally support previously proposed, subjective life history-based classifications of freshwater fish species in this region. The majority of species fell into two groups, with 18 and 19 species, and the



The cyanobacterial neurotoxin ?-N-methylamino-l-alanine (BMAA) induces neuronal and behavioral changes in honeybees.  


The cyanobacterially produced neurotoxin beta-N-methylamino-l-alanine (BMAA) is thought to induce amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC)-like symptoms. However, its mechanism of action and its pathway of intoxication are yet unknown. In vivo animal models suitable for investigating the neurotoxic effect of BMAA with applicability to the human are scarce. Hence, we used the honeybee (Apis mellifera) since its nervous system is relatively simple, yet having cognitive capabilities. Bees fed with BMAA-spiked sugar water had an increased mortality rate and a reduced ability to learn odors in a classical conditioning paradigm. Using (14)C-BMAA we demonstrated that BMAA is biologically available to the bee, and is found in the head, thorax and abdomen with little to no excretion. BMAA is also transferred from one bee to the next via trophallaxis resulting in an exposure of the whole beehive. BMAA bath application directly onto the brain leads to an altered Ca(2+) homeostasis and to generation of reactive oxygen species. These behavioral and physiological observations suggest that BMAA may have effects on bee brains similar to those assumed to occur in humans. Therefore the bee could serve as a surrogate model system for investigating the neurological effects of BMAA. PMID:23591064

Okle, Oliver; Rath, Lisa; Galizia, C Giovanni; Dietrich, Daniel R



Effect of cyanobacterial exopolysaccharides on salt stress alleviation and seed germination.  


Effectof exopolysaccharides (EPS) produced by a consortium of cyanobacteria on germination of three crops wheat, maize and rice was studied at different salt concentrations. Production of EPS was found to be stimulated by salts, which in turn had a significant Na+ removal capability from aqueous solution. Seed germination, vigor index and mobilization efficiency in all the three crops remarkably improved when cyanobacterial EPS was applied. While germination improved significantly by 13 to 30%, mobilization efficiency increased marginally by 1.03 to 1.1 times and vigor index increased by 1.15 to 2.4 times in these crops in response to EPS under non-saline conditions. Salinity had an inhibitory effect on seed germination of all the species showing 18 to 54% reduction. However, in the presence of EPS, the salt induced inhibition diminished to 13 to 18%. Inhibitory effect of salt on chlorophyll concentration, vigor index and mobilization efficiency of the seedlings was much less in these crops in the presence of EPS, indicating the latter's role in salt stress alleviation. PMID:21387925

Arora, Monu; Kaushik, A; Rani, Nisha; Kaushik, C P



Enzymatic pathway for the bacterial degradation of the cyanobacterial cyclic peptide toxin microcystin LR.  

PubMed Central

An isolated bacterium, identified as a new Sphingomonas species, was demonstrated to contain a novel enzymatic pathway which acted on microcystin LR, the most common cyanobacterial cyclic peptide toxin. Degradation of microcystin LR was mediated by at least three intracellular hydrolytic enzymes. The use of classic protease inhibitors allowed (i) the classification of these enzymes into general protease families and (ii) the in vitro accumulation of otherwise transient microcystin LR degradation products. The initial site of hydrolytic cleavage of the parent cyclic peptide by an enzyme that we designate microcystinase is at the 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda)-Arg peptide bond. Two intermediates of microcystin LR enzymatic degradation have been identified; one is linearized (acyclo-) microcystin LR, NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-Leu-beta-methylas partate-Arg-OH, and the other is the tetrapeptide NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-OH. The intermediate degradation products were less active than the parent cyclic peptide; the observed 50% inhibitory concentrations for crude chicken brain protein phosphatase were 0.6 nM for microcystin LR, 95 nM for linear LR, and 12 nM for the tetrapeptide. These linear peptides were nontoxic to mice at doses up to 250 micrograms/kg. Ring opening of the potent hepatotoxin microcystin LR by bacterial microcystinase effectively renders the compound nontoxic by dramatically reducing the interaction with the target protein phosphatase.

Bourne, D G; Jones, G J; Blakeley, R L; Jones, A; Negri, A P; Riddles, P



Cyanobacterial blooms in stratified and destratified eutrophic reservoirs in semi-arid region of Brazil.  


This study investigated the dynamics of cyanobacteria in two deep, eutrophic reservoirs in a semi-arid region of Brazil during periods of stratification and destratification. Four collections were carried out at each reservoir at two depths at three-month intervals. The following abiotic variables were analyzed: water temperature, dissolved oxygen, pH, turbidity, water transparency, total phosphorus, total dissolved phosphorus, orthophosphate and total nitrogen. Phytoplankton density was quantified for the determination of the biomass of cyanobacteria. The data were analyzed using CCA. Higher mean phytoplankton biomass values (29.8 mm(3).L(-1)) occurred in the period of thermal stratification. A greater similarity in the phytoplankton communities also occurred in this period and was related to the development of cyanobacteria, mainly Cylindrospermopsis raciborskii (>3.9 mm(3).L(-1)). During the period of thermal destratification, this species co-dominated the environment with Planktothrix agardhii, Geitlerinema amphibium, Microcystis aeruginosa and Merismopedia tenuissima, as well as with diatoms and phytoflagellates. Environmental instability and competition among algae hindered the establishment of blooms more during the mixture period than during the stratification period. Thermal changes in the water column caused by climatologic events altered other physiochemical conditions of the water, leading to changes in the composition and biomass of the cyanobacterial community in tropical reservoirs. PMID:22146960

Dantas, Enio W; Moura, Ariadne N; Bittencourt-Oliveira, Maria do Carmo



One new species and records of Ichthydium Ehrenberg, 1830 (Gastrotricha: Chaetonotida) from Sweden with a key to the genus  

Microsoft Academic Search

The freshwater gastrotrich fauna of Sweden is poorly known. Only seven species of freshwater gastrotrichs have been reported so far. This paper is the first in a series of contributions about the Swedish freshwater gastrotrich fauna. Here we describe one new species, Ichthydium skandicum n. sp., from Jämtland, northern Sweden. The new species falls within the boundary of the subgenus



Habitat suitability for three species of Anopheles mosquitoes: larval growth and survival in reciprocal placement experiments.  


Larval habitats of the main malaria vectors in Belize are associated with three distinctly different aquatic environments: marshes with sparse macrophytes and cyanobacterial mats (Anopheles albimanus), tall dense macrophyte marshes (An. vestitipennis), and floating detritus assemblages within freshwater rivers (An. darlingi). We assessed species-specific habitat suitability based upon nutrient characteristics using larval survival rates (SR) and wing lengths (WL) from floating habitat enclosures. Anopheles albimanus showed a high SR (81%) in all three habitats, while An. vestitipennis had a similarly high SR in its own habitat (82%) and An. darlingi's habitat (81%). Anopheles darlingi only showed high SR (85%) in its own habitat. Both An. vestitipennis and An. darlingi showed very low SR in the An. albimanus habitat. There were no significant WL differences among field-caught, laboratory-reared, and experimental populations of An. vestitipennis and An. albimanus, with the exception of An. vestitipennis experimental populations and An. vestitipennis field populations placed in the An. albimanus habitat. Habitat quality indicators, particulate organic carbon (POC), dissolved organic carbon (DOC), and particulate organic nitrogen (PON), were consistently higher in An. vestitipennis habitats than in the habitats of the other two species. Correspondingly, An. vestitipennis adults were larger when measured both as dry mass and from WL. There were no differences in dry mass, lipids, or protein content among the same species reared at different locations. We compared SR and WL among mosquitoes from shaded and unshaded containers to test whether the high mortality rates for An. vestitipennis and An. darlingi in the An. albimanus habitat were due to intense sun exposure. There were no significant differences among developmental times, survivorship, or adult size for shaded versus sun-exposed populations. This indicates that other factors such as larval toxins, predator avoidance, interspecific species competition, etc. may be responsible for the higher mortality rates in those species not adapted to this particular habitat. PMID:18260505

Grieco, John P; Rejmánková, Eliska; Achee, Nicole L; Klein, Corinne N; Andre, Richard; Roberts, Donald



Nested structure of plankton communities from Chilean freshwaters  

Microsoft Academic Search

1.Nestedness has been recognized as a characteristic pattern of community organization. In a nested metacommunity, species-poor sites are proper subsets of relatively richer sites, implying that the conservation of many poor habitats can be ineffective.2.Here we compiled the last 30 years of published limnological research on Chilean lakes, in order to determine whether or not species distribution of freshwater plankton

Rodrigo Ramos-Jiliberto; J. Pablo Oyanedel; Caren Vega-Retter; Fernanda S. Valdovinos



Aggressive interactions during feeding between native and invasive freshwater turtles  

Microsoft Academic Search

The red-eared slider (Trachemys scripta elegans) is a worldwide highly invasive species, currently introduced in most freshwater habitats as a consequence of massive pet\\u000a trade. In the Iberian Peninsula, this species is competing with and displacing the endangered native Spanish terrapin (Mauremys leprosa). Sliders are considered environmentally-aggressive turtles, capable of threatening or biting other individuals during competitive\\u000a activities such as

Nuria Polo-CaviaPilar; Pilar López; José Martín



Establishing a database of radionuclide transfer parameters for freshwater wildlife.  


Environmental assessments to evaluate potentials risks to humans and wildlife often involve modelling to predict contaminant exposure through key pathways. Such models require input of parameter values, including concentration ratios, to estimate contaminant concentrations in biota based on measurements or estimates of concentrations in environmental media, such as water. Due to the diversity of species and the range in physicochemical conditions in natural ecosystems, concentration ratios can vary by orders of magnitude, even within similar species. Therefore, to improve model input parameter values for application in aquatic systems, freshwater concentration ratios were collated or calculated from national grey literature, Russian language publications, and refereed papers. Collated data were then input into an international database that is being established by the International Atomic Energy Agency. The freshwater database enables entry of information for all radionuclides listed in ICRP (1983), in addition to the corresponding stable elements, and comprises a total of more than 16,500 concentration ratio (CR(wo-water)) values. Although data were available for all broad wildlife groups (with the exception of birds), data were sparse for many organism types. For example, zooplankton, crustaceans, insects and insect larvae, amphibians, and mammals, for which there were CR(wo-water) values for less than eight elements. Coverage was most comprehensive for fish, vascular plants, and molluscs. To our knowledge, the freshwater database that has now been established represents the most comprehensive set of CR(wo-water) values for freshwater species currently available for use in radiological environmental assessments. PMID:23103210

Yankovich, T; Beresford, N A; Fesenko, S; Fesenko, J; Phaneuf, M; Dagher, E; Outola, I; Andersson, P; Thiessen, K; Ryan, J; Wood, M D; Bollhöfer, A; Barnett, C L; Copplestone, D



Toxicity of cyanobacterial bloom in the eutrophic dam reservoir (Southeast Poland).  


Cyanobacterial bloom was observed in a highly eutrophic dam reservoir, Zemborzycki, near Lublin (SE Poland) over a warm period in the year 2007. The water bloom consisted of several cyanobacterial taxa: Anabaena circinalis, Anabaena spiroides, Anabaena flos-aquae, Planktothrix agardhii, Aphanizomenon flos-aquae, Aphanizomenon gracile, and Microcystis flos-aquae. Anabaena spp., and Aphanizomenon spp., potential producers of neurotoxic anatoxin-a, quantitatively predominated in the studied bloom. High-performance liquid chromatography (HPLC) analysis of surface scum sampled during Anabaena circinalis domination revealed the presence of anatoxin-a at a high concentration (1,035.59 microg per liter of surface scum). At the same time, neither gas chromatography/mass spectrometry (GC/MS) nor microcystin enzyme-linked immunosorbent assay (ELISA) test showed the presence of other frequently found cyanotoxins, microcystins. Toxicity of cyanobacterial bloom was assessed by the crustacean acute toxicity test Daphtoxkit F pulex using Daphnia pulex, and by the chronic toxicity test Protoxkit F with a ciliate protozoan Tetrahymena thermophila. The crude extract of cyanobacterial scum showed high toxicity for Daphnia pulex, with 24-h median effective concentration (EC50) value of 90.3 microg/L of anatoxin-a, which corresponded to the cyanobacterial density in the scum of 1.01 g dry weight/L. For Tetrahymena thermophila, 24-h EC50 was lower, evaluated to be 60.48 microg/L of anatoxin-a, which corresponded to a cyanobacterial density of 0.68 g dry weight/L of the scum. On the basis of evaluated toxicity units, the cyanobacterial extract was classified at class IV toxicity, which means high toxic hazard. PMID:20821478

Sieros?awska, Anna; Rymuszka, Anna; Kalinowska, Renata; Skowro?ski, Tadeusz; Bownik, Adam; Pawlik-Skowro?ska, Barbara



Spatial heterogeneity of cyanobacterial communities and genetic variation of microcystis populations within large, shallow eutrophic lakes (Lake Taihu and Lake Chaohu, China).  


Cyanobacteria, specifically Microcystis, usually form massive blooms in eutrophic freshwater lakes. Cyanobacterial samples were collected from eight sites of both Lake Taihu and Lake Chaohu in late summer to determine the diversity and distribution pattern of cyanobacteria and Microcystis in large, shallow, entropic lakes with significant spatial heterogeneity and long-term Microcystis bloom. Molecular methods based on denaturing gradient gel electrophoresis and clone library analysis were used. A similar heterogeneous distribution pattern of cyanobacteria in both lakes was observed. Most parts of these two lakes with high trophic level were dominated by Microcystis. However, in the regions with low trophic levels as well as low concentrations of chlorophyll a, Synechococcus occupied a considerable percentage. Different morphospecies and genotypes dominated the bloom-forming Microcystis populations in these two lakes. Microcystis viridis and Microcystis novacekii were dominant in Lake Chaohu, whereas Microcystis flos-aquae was dominant in Lake Taihu. Only 2 of thel3 Microcystis operational taxonomic units were shared between these two lakes. Analysis of molecular variance based on 16S to 23S internal transcribed spacer sequences indicated the significAnt genetic differentiation of Microcystis between these two lakes (F(ST) = 0.19, p < 0.001). However, only 19.46% of the genetic variability was explained by the population variation between lakes, whereas most (80.54%) of the genetic variability occurred within the lakes. Phylogenetic analysis revealed no phylogeographic structure of Microcystis population in these two lakes, as illustrated by their cosmopolitan nature. Our results revealed that spatial heterogeneity within lakes has more impact on the cyanobacterial diversity than geographical isolation in a local scale. PMID:23520854

Cai, Yuanfeng; Kong, Fanxiang; Shi, Limei; Yu, Yang



Physiological and biochemical defense reactions of Vicia faba L.-Rhizobium symbiosis face to chronic exposure to cyanobacterial bloom extract containing microcystins.  


The presence of cyanotoxins, mainly microcystins (MCs), in surface freshwater represents a serious health risk to aquatic organisms living in the water body, as well as terrestrial animals and plants that are in contact with contaminated water. Consequently, the use of MCs contaminated water for irrigation represents a hazard for cultivated plants and could induce severe economical losses due to crops' yield reduction. The experimental approach undertaken in this work was exposing Vicia faba seedlings (inoculated with a Rhizobium strain resistant to MCs), to water supplemented with cyanobacterial crude extract containing total microcystins at a concentration of 50 and 100 ?g/L (environmental relevant concentrations of MCs dissolved in the raw irrigation water from Lalla Takerkoust Lake-Marrakesh region). After chronic MCs exposure (2 months), biological and physiological parameters (plant growth, nitrogen uptake, mineral assimilation, and oxidative defense mechanisms) were evaluated. The results obtained showed evidence that chronic exposure to cyanobacterial bloom extract containing MCs strongly affected the physiological and biological plants activities; reduction of dry matter, photosynthetic activity, nodule number, and nitrogen assimilation. At the same time, an increase of oxidative stress was observed, as deduced from a significant increase of the activities of peroxidase, catalase, polyphenoloxidase, and phenylalanine ammonia lyase in leaves, roots, and nodules of faba bean plants exposed to cyanotoxins, especially at 100 ?g/L of MCs. This experimentation constitutes a simulation of the situation related to cyanotoxins chronic exposure of seedlings-plants via the contaminated irrigation water. For this reason, once should take into consideration the possibility of contamination of agricultural crops and the quality of irrigation water should be by the way monitored for cyanotoxins biohazard. PMID:23417437

Lahrouni, Majida; Oufdou, Khalid; El Khalloufi, Fatima; Baz, Mohamed; Lafuente, Alejandro; Dary, Mohammed; Pajuelo, Eloisa; Oudra, Brahim



The monophyletic origin of freshwater crayfish estimated from nuclear and mitochondrial DNA sequences.  

PubMed Central

Despite their widespread use as model organisms, the phylogenetic status of the around 520 species of freshwater crayfish is still in doubt. One hypothesis suggests two distinct origins of freshwater crayfish as indicated by their geographical distribution, with two centres of origin near the two present centres of diversity; one in south-eastern United States and the other in Victoria, Australia. An alternative theory proposes a single (monophyletic) origin of freshwater crayfish. Here we use over 3000 nucleotides from three different gene regions in estimating phylogenetic relationships among freshwater crayfish and related Crustacea. We show clear evidence for monophyly of freshwater crayfish and for the sister-group relationship between crayfish and clawed lobsters. Monophyly of the superfamilies Astacoidea and Parastacoidea is also supported. However, the monophyly of the family Cambaridae is questioned with the genus Cambaroides being associated with the Astacidae.

Crandall, K A; Harris, D J; Fetzner, J W



Life history and ecological correlates of extinction risk in European freshwater fishes  

Microsoft Academic Search

We used phylogenetically based comparative analyses to test for associations between extinction risk in European freshwater fishes and a variety of life history, ecological, and biogeographical traits. Based on the World Conservation Union classification scheme, a total of 47% of Europe's 287 native species are classified as threatened with extinction. Threatened species are significantly smaller than less-threatened species in the

John D. Reynolds; Thomas J. Webb; Lorraine A. Hawkins



Diversity, endemism and conservation of the freshwater crabs of China (Brachyura: Potamidae and Gecarcinucidae).  


China lies at the heart of the global center of freshwater crab diversity in tropical Asia, where the 2 most diverse families occur: Potamidae (505 species, 95 genera) and Gecarcinucidae (344 species, 59 genera). China stands out as the country with the highest species richness of freshwater crabs globally. Its fauna comprises 243 species in 37 genera and in 2 families, and species discovery is still progressing at a rapid pace. The vast majority of the species are distributed in southwest, south central and eastern China in the Oriental zoogeographical region. China also stands out as having a highly endemic freshwater crab fauna at the species level (96%) and at the genus level (78%). Although the recent International Union for the Conservation of Nature (IUCN) red list conservation assessment found only 6 out of 228 species (2%) to be threatened (5 potamids and 1 gecarcinucid), the majority (more than 75%) of Chinese species are regarded as data deficient, so the number of threatened species is likely to be a serious underestimate. Threats from increasing habitat destruction and pollution are a major concern due to the rapidly growing economy and massive developments taking place in China. There is therefore an urgent need for increased species exploration and for the development of a conservation strategy for China's threatened (and potentially threatened) endemic freshwater crab species. PMID:21392361

Cumberlidge, Neil; Ng, Peter K L; Yeo, Darren C J; Naruse, Tohru; Meyer, Kirstin S; Esser, Lara J



Temnocephalan symbionts of the freshwater crayfish Cherax quadricarinatus from northern Australia  

Microsoft Academic Search

Four species of turbellarian temnocephalan symbionts (Platyhelminthes: Temnocephalida) are reported for the first time from the external surfaces of Cherax quadricarinatus, a freshwater crayfish from northern Australia. Three of these species — Temnocephala rouxii Merton, 1913, Notodactylus handschini (Baer, 1945), and Diceratocephala boschmai Baer, 1953 — are known previously from related crayfish in New Guinea. The newly discovered fourth species,

Lester R. G. Cannon



Endemic freshwater invertebrates from southern France: Diversity, distribution and conservation implications  

Microsoft Academic Search

Freshwaters ecosystems continue to face pressures from pollution, flow regime alterations, habitat destruction and exotic species invasions despite their unique biodiversity. In Europe, National Parks and Special Areas of Conservation aim to provide protection of ‘aggregate’ biodiversity, yet inspection of priority species lists for these sites often reveals a focus towards terrestrial species. In regions such as the Alps and

Lee E. Brown; Régis Céréghino; Arthur Compin



Mutational Analysis of the Cyanobacterial Nitrogen Regulator PipX  

PubMed Central

PipX provides a functional link between the cyanobacterial global transcriptional regulator NtcA and the signal transduction protein PII, a protein found in all three domains of life as integrators of signals of the nitrogen and carbon balance. PipX, which is toxic in the absence of PII, can form alternative complexes with NtcA and PII and these interactions are respectively stimulated and inhibited by 2-oxoglutarate, providing a mechanism by which PII can modulate expression at the NtcA regulon. Structural information on PipX-NtcA complexes suggests that PipX coactivates NtcA controlled genes by stabilizing the active conformation of NtcA bound to 2-oxoglutarate and by possibly helping recruit RNA polymerase. To get insights into PipX functions, we perform here a mutational analysis of pipX informed by the structures of PipX-PII and PipX-NtcA complexes and evaluate the impact of point mutations on toxicity and gene expression. Two amino acid substitutions (Y32A and E4A) were of particular interest, since they increased PipX toxicity and activated NtcA dependent genes in vivo at lower 2-oxoglutarate levels than wild type PipX. While both mutations impaired complex formation with PII, only Y32A had a negative impact on PipX-NtcA interactions.

Laichoubi, Karim Boumediene; Espinosa, Javier; Castells, Miguel Angel; Contreras, Asuncion



Anti-cyanobacterial activity of Moringa oleifera seeds  

PubMed Central

Filtrates from crushed Moringa oleifera seeds were tested for their effects on growth and Photosystem II efficiency of the common bloom-forming cyanobacterium Microcystis aeruginosa. M. aeruginosa populations exhibited good growth in controls and treatments with 4- and 8-mg crushed Moringa seeds per liter, having similar growth rates of 0.50 (±0.01) per day. In exposures of 20- to 160-mg crushed Moringa seeds L?1, growth rates were negative and on average ?0.23 (±0.05) .day?1. Presumably, in the higher doses of 20- to 160-mg crushed seeds per liter, the cyanobacteria died, which was supported by a rapid drop in the Photosystem II efficiency (?PSII), while the ?PSII was high and unaffected in 0, 4, and 8 mg L?1. High-density populations of M. aeruginosa (chlorophyll-a concentrations of ?270 µg L?1) were reduced to very low levels within 2 weeks of exposure to ?80-mg crushed seeds per liter. At the highest dosage of 160 mg L?1, the ?PSII dropped to zero rapidly and remained nil during the course of the experiment (14 days). Hence, under laboratory conditions, a complete wipeout of the bloom could be achieved. This is the first study that yielded evidence for cyanobactericidal activity of filtrate from crushed Moringa seeds, suggesting that Moringa seed extracts might have a potential as an effect-oriented measure lessening cyanobacterial nuisance.

Beekman, Wendy



Engineering a cyanobacterial cell factory for production of lactic acid.  


Metabolic engineering of microorganisms has become a versatile tool to facilitate production of bulk chemicals, fuels, etc. Accordingly, CO(2) has been exploited via cyanobacterial metabolism as a sustainable carbon source of biofuel and bioplastic precursors. Here we extended these observations by showing that integration of an ldh gene from Bacillus subtilis (encoding an l-lactate dehydrogenase) into the genome of Synechocystis sp. strain PCC6803 leads to l-lactic acid production, a phenotype which is shown to be stable for prolonged batch culturing. Coexpression of a heterologous soluble transhydrogenase leads to an even higher lactate production rate and yield (lactic acid accumulating up to a several-millimolar concentration in the extracellular medium) than those for the single ldh mutant. The expression of a transhydrogenase alone, however, appears to be harmful to the cells, and a mutant carrying such a gene is rapidly outcompeted by a revertant(s) with a wild-type growth phenotype. Furthermore, our results indicate that the introduction of a lactate dehydrogenase rescues this phenotype by preventing the reversion. PMID:22865063

Angermayr, S Andreas; Paszota, Michal; Hellingwerf, Klaas J



Engineering a Cyanobacterial Cell Factory for Production of Lactic Acid  

PubMed Central

Metabolic engineering of microorganisms has become a versatile tool to facilitate production of bulk chemicals, fuels, etc. Accordingly, CO2 has been exploited via cyanobacterial metabolism as a sustainable carbon source of biofuel and bioplastic precursors. Here we extended these observations by showing that integration of an ldh gene from Bacillus subtilis (encoding an l-lactate dehydrogenase) into the genome of Synechocystis sp. strain PCC6803 leads to l-lactic acid production, a phenotype which is shown to be stable for prolonged batch culturing. Coexpression of a heterologous soluble transhydrogenase leads to an even higher lactate production rate and yield (lactic acid accumulating up to a several-millimolar concentration in the extracellular medium) than those for the single ldh mutant. The expression of a transhydrogenase alone, however, appears to be harmful to the cells, and a mutant carrying such a gene is rapidly outcompeted by a revertant(s) with a wild-type growth phenotype. Furthermore, our results indicate that the introduction of a lactate dehydrogenase rescues this phenotype by preventing the reversion.

Angermayr, S. Andreas; Paszota, Michal



Form changes in the sea bass, Dicentrarchus labrax (Moronidae: Teleostei), after acclimation to freshwater: an analysis using shape coordinates  

Microsoft Academic Search

Morphological changes in the sea bass, Dicentrarchus labrax (Perciformes: Moronidae), were investigated after an experimental acclimation trial to freshwater. The sea bass is an euryhaline species occurring in the Mediterranean and west Atlantic from 30° N to 55° N. Part of the offspring of a pool of breeders was acclimated to freshwater at 9 months of age while maintaining the

Marco Corti; Angelo Loy; Stefano Cataudella



Phytoplankton development and ecological status during a cyanobacterial bloom in a tributary bay of the Three Gorges Reservoir, China.  


Reservoirs can provide suitable conditions for cyanobacterial bloom development, which may impact on water quality and biological communities. Weekly surveys in a cyanobacterial bloom process were carried out in the mainstream and Xiangxi Bay of the Three Gorges Reservoir (China), from June 6 to July 18 in 2008. By application of the phytoplankton functional group approach, the spatiotemporal pattern, impact factors, and the ecological status based on Q index (assemblage index) were analyzed. The depth of euphotic layer was apparently the key factor driving the phytoplankton functional group variations. Longitudinal patterns of phytoplankton distribution were detected during this bloom: in the beginning phase, groups D (mainly Stephanodiscus hantzschii) and B (Cyclotella stelligera) dominated in the mainstream of the Three Gorges Reservoir and the mouth area of Xiangxi Bay, group Y (Cryptomonas species) dominated in the upper area, while groups J (mainly Pediastrum duplex), F (mainly Sphaerocystis schroeteri) and G (Pandorina morum and Eudorina elegans) were important in other areas; in the mid phase, group M became absolutely dominant in the whole region; and in the ending phase, besides groups M and Y, groups X2 (Chroomonas acuta, Pyramimonas nanella, etc.) and Lo (Ceratium hirundinella) became more important in the lower and upper area respectively. Generally the ecological status was bad, temporally varied with the bloom process. No spatial difference of ecological status was found in the mainstream, while longitudinal patterns in Xiangxi Bay were detected for different phases: firstly a few sites had relatively better status than the others, then nearly all the sites were in the bad condition, and at last the status in the downstream was better than that in the upstream. The longitudinal patterns of ecological status were related to phytoplankton distribution, disturbed by jacking from the downstream and flood from the upstream of Xiangxi Bay. PMID:21752429

Wang, Lan; Cai, Qinghua; Tan, Lu; Kong, Linghui



40 CFR 35.1605-3 - Publicly owned freshwater lake.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Publicly owned freshwater lake. 35.1605-3 Section 35.1605-3...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public...