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1

Secondary metabolite gene expression and interplay of bacterial functions in a tropical freshwater cyanobacterial bloom  

E-print Network

Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and ...

Penn, Kevin

2

Screening of Cyanobacterial Species for Calcification  

SciTech Connect

Species of cyanobacteria in the genera Synechococcus and Synechocystis are known to be the catalysts of a phenomenon called "whitings", which is the formation and precipitation of fine-grained CaCO3 particles. Whitings occur when the cyanobacteria fix atmospheric CO2 through the formation of CaCO3 on their cell surfaces, which leads to precipitation to the ocean floor and subsequent entombment in mud. Whitings represent one potential mechanism for CO2 sequestration. Research was performed to determine the ability of various strains of Synechocystis and Synechococcus to calcify when grown in microcosms amended with 2.5 mM HCO3- and 3.4 mM Ca2+. Results indicated that although all strains tested have the ability to calcify, only two Synechococcus species, strains PCC 8806 and PCC 8807, were able to calcify to the extent that a CaCO3 precipitate was formed. Enumeration of the cyanobacterial cultures during testing indicated that cell density did not appear to have a direct effect on calcification. Factors that had the greatest effect on calcification were CO2 removal and subsequent generation of alkaline pH. Whereas cell density was similar for all strains tested, differences in maximum pH were demonstrated. As CO2 was removed, growth medium pH increased and soluble Ca2+ was removed from solution. The largest increases in growth medium pH occurred when CO2 levels dropped below 400 ppmv. Research presented demonstrates that, under the conditions tested, many species of cyanobacteria in the genera Synechocystis and Synechococcus are able to calcify but only two species of Synechococcus were able to calcify to an extent that led to the precipitation of calcium carbonate.

Brady D. Lee; William A. Apel; Michelle R. Walton

2004-07-01

3

Competitive exclusion of Cyanobacterial species in the Great Salt Lake  

Microsoft Academic Search

The Great Salt Lake is separated into different salinity regimes by rail and vehicular causeways. Cyanobacterial distributions\\u000a 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\\u000a excluded from the south, and if

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

2009-01-01

4

Sporadic Distribution and Distinctive Variations of Cylindrospermopsin Genes in Cyanobacterial Strains and Environmental Samples from Chinese Freshwater Bodies  

PubMed Central

Increasing reports of cylindrospermopsins (CYNs) in freshwater ecosystems have promoted the demand for identifying all of the potential CYN-producing cyanobacterial species. The present study explored the phylogenetic distribution and evolution of cyr genes in cyanobacterial strains and water samples from China. Four Cylindrospermopsis strains and two Raphidiopsis strains were confirmed to produce CYNs. Mutant cyrI and cyrK genes were observed in these strains. Cloned cyr gene sequences from eight water bodies were clustered with cyr genes from Cylindrospermopsis and Raphidiopsis (C/R group) in the phylogenetic trees with high similarities (99%). Four cyrI sequence types and three cyrJ sequence types were observed to have different sequence insertions and repeats. Phylogenetic analysis of the rpoC1 sequences of the C/R group revealed four conserved clades, namely, clade I, clade II, clade III, and clade V. High sequence similarities (>97%) in each clade and a divergent clade IV were observed. Therefore, CYN producers were sporadically distributed in congeneric and paraphyletic C/R group species in Chinese freshwater ecosystems. In the evolution of cyr genes, intragenomic translocations and intergenomic transfer between local Cylindrospermopsis and Raphidiopsis were emphasized and probably mediated by transposases. This research confirms the existence of CYN-producing Cylindrospermopsis in China and reveals the distinctive variations of cyr genes. PMID:24928879

Jiang, Yongguang; Xiao, Peng; Yu, Gongliang; Shao, Jihai; Liu, Deming; Azevedo, Sandra M. F. O.

2014-01-01

5

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

2005-01-01

6

The presence of microcystins and other cyanobacterial bioactive peptides in aquatic fauna collected from Greek freshwaters  

Microsoft Academic Search

Toxic bloom-forming cyanobacteria can cause animal death and adversely affect human health. Blooms may contain microcystins (MCs), cyanobacterial heptapeptide hepatotoxins and other peptides such as anabaenopeptins and anabaenopeptilides. MCs have been shown to occur in various aquatic organisms including mussels, water snails, crustaceans and fish. Muscle and viscera samples from eight species of fish (Acipenser gueldenstaedtii, Carassius auratus, Carassius gibelio,

S. Gkelis; T. Lanaras; K. Sivonen

2006-01-01

7

SAR analysis and bioactive potentials of freshwater and terrestrial cyanobacterial compounds: a review.  

PubMed

Freshwater and terrestrial cyanobacteria resemble the marine forms in producing divergent chemicals such as linear, cyclic and azole containing peptides, alkaloids, cyclophanes, terpenes, lactones, etc. These metabolites have wider biomedical potentials in targeting proteases, cancers, parasites, pathogens and other cyanobacteria and algae (allelopathy). Among the various families of non-marine cyanobacterial peptides reported, many of them are acting as serine protease inhibitors. While the micropeptin family has a preference for chymotrypsin inhibition rather than other serine proteases, the aeruginosin family targets trypsin and thrombin. In addition, cyanobacterial compounds such as scytonemide A, lyngbyazothrins C and D and cylindrocyclophanes were found to inhibit 20S proteosome. Apart from proteases, metabolites blocking the other targets of cancer pathways may exhibit cytotoxic effect. Colon and rectum, breast, lung and prostate are the worst affecting cancers in humans and are deduced to be inhibited by both peptidic and non-peptidic compounds. Moreover, the growth of infections causing parasites such as Plasmodium, Leishmania and Trypanosoma are well controlled by peptides: aerucyclamides A-D, tychonamides and alkaloids: nostocarboline and calothrixins. Likewise, varieties of cyanobacterial compounds tend to inhibit serious infectious disease causing bacterial, fungal and viral agents. Interestingly, portoamides, spiroidesin, nostocyclamide and kasumigamide are the allelopathic peptides determined to suppress the growth of toxic cyanobacteria and nuisance algae. Thus cyanobacterial compounds have a broad bioactive spectrum; the analysis of SAR studies will not only assist to find out the mode of action but also reveal bioactive key components. Thereby, developing the drugs bearing these bioactive skeletons to treat various illnesses is wide open. PMID:23172644

Nagarajan, M; Maruthanayagam, V; Sundararaman, M

2013-05-01

8

Secondary metabolite gene expression and interplay of bacterial functions in a tropical freshwater cyanobacterial bloom  

PubMed Central

Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and recreation. To characterize microbial activities in a cyanoHAB, transcripts from a eutrophic freshwater reservoir in Singapore were sequenced for six samples collected over one day-night period. Transcripts from the Cyanobacterium Microcystis dominated all samples and were accompanied by at least 533 genera primarily from the Cyanobacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Within the Microcystis population, abundant transcripts were from genes for buoyancy, photosynthesis and synthesis of the toxin microviridin, suggesting that these are necessary for competitive dominance in the Reservoir. During the day, Microcystis transcripts were enriched in photosynthesis and energy metabolism while at night enriched pathways included DNA replication and repair and toxin biosynthesis. Microcystis was the dominant source of transcripts from polyketide and non-ribosomal peptide synthase (PKS and NRPS, respectively) gene clusters. Unexpectedly, expression of all PKS/NRPS gene clusters, including for the toxins microcystin and aeruginosin, occurred throughout the day-night cycle. The most highly expressed PKS/NRPS gene cluster from Microcystis is not associated with any known product. The four most abundant phyla in the reservoir were enriched in different functions, including photosynthesis (Cyanobacteria), breakdown of complex organic molecules (Proteobacteria), glycan metabolism (Bacteroidetes) and breakdown of plant carbohydrates, such as cellobiose (Actinobacteria). These results provide the first estimate of secondary metabolite gene expression, functional partitioning and functional interplay in a freshwater cyanoHAB. PMID:24646695

Penn, Kevin; Wang, Jia; Fernando, Samodha C; Thompson, Janelle R

2014-01-01

9

Secondary metabolite gene expression and interplay of bacterial functions in a tropical freshwater cyanobacterial bloom.  

PubMed

Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and recreation. To characterize microbial activities in a cyanoHAB, transcripts from a eutrophic freshwater reservoir in Singapore were sequenced for six samples collected over one day-night period. Transcripts from the Cyanobacterium Microcystis dominated all samples and were accompanied by at least 533 genera primarily from the Cyanobacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Within the Microcystis population, abundant transcripts were from genes for buoyancy, photosynthesis and synthesis of the toxin microviridin, suggesting that these are necessary for competitive dominance in the Reservoir. During the day, Microcystis transcripts were enriched in photosynthesis and energy metabolism while at night enriched pathways included DNA replication and repair and toxin biosynthesis. Microcystis was the dominant source of transcripts from polyketide and non-ribosomal peptide synthase (PKS and NRPS, respectively) gene clusters. Unexpectedly, expression of all PKS/NRPS gene clusters, including for the toxins microcystin and aeruginosin, occurred throughout the day-night cycle. The most highly expressed PKS/NRPS gene cluster from Microcystis is not associated with any known product. The four most abundant phyla in the reservoir were enriched in different functions, including photosynthesis (Cyanobacteria), breakdown of complex organic molecules (Proteobacteria), glycan metabolism (Bacteroidetes) and breakdown of plant carbohydrates, such as cellobiose (Actinobacteria). These results provide the first estimate of secondary metabolite gene expression, functional partitioning and functional interplay in a freshwater cyanoHAB. PMID:24646695

Penn, Kevin; Wang, Jia; Fernando, Samodha C; Thompson, Janelle R

2014-09-01

10

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

PubMed

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

2008-01-01

11

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.

2009-04-01

12

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

13

Avian vacuolar myelinopathy linked to exotic aquatic plants and a novel cyanobacterial species.  

PubMed

Invasions of exotic species have created environmental havoc through competition and displacement of native plants and animals. The introduction of hydrilla (Hydrilla verticillata) into the United States in the 1960s has been detrimental to navigation, power generation, water intake, and water quality (McCann et al., 1996). Our field surveys and feeding studies have now implicated exotic hydrilla and associated epiphytic cyanobacterial species as a link to avian vacuolar myelinopathy (AVM), an emerging avian disease affecting herbivorous waterbirds and their avian predators. AVM, first reported in 1994, has caused the death of at least 100 bald eagles (Haliaeetus leucocephalus) and thousands of American coots (Fulica americana) at 11 sites from Texas to North Carolina (Thomas et al., 1998; Rocke et al., 2002). Our working hypothesis is that the agent of this disease is an uncharacterized neurotoxin produced by a novel cyanobacterial epiphyte of the order Stigonematales. This undescribed species covers up to 95% of the surface area of leaves in reservoirs where bird deaths have occurred from the disease. In addition, this species is rare or not found on hydrilla collected at sites where AVM disease has not been diagnosed. Laboratory feeding trials and a sentinel bird study using naturally occurring blooms of cyanobacteria on hydrilla leaves and farm-raised mallard ducks (Anas platyrhynchos) induced the disease experimentally. Since 1994 AVM has been diagnosed in additional sites from Texas to North Carolina. Specific site characteristics that produce the disjunct distribution of AVM are unknown, but it is probable that the incidence of this disease will increase with the introduction of hydrilla and associated cyanobacterial species into additional ponds, lakes, and reservoirs. PMID:15892059

Wilde, Susan B; Murphy, Thomas M; Hope, Charlotte P; Habrun, Sarah K; Kempton, Jason; Birrenkott, Anna; Wiley, Faith; Bowerman, William W; Lewitus, Alan J

2005-06-01

14

Bacterial Community Composition of Size-Fractioned Aggregates within the Phycosphere of Cyanobacterial Blooms in a Eutrophic Freshwater Lake  

PubMed Central

Bacterial community composition of different sized aggregates within the Microcystis cyanobacterial phycosphere were determined during summer and fall in Lake Taihu, a eutrophic lake in eastern China. Bloom samples taken in August and September represent healthy bloom biomass, whereas samples from October represent decomposing bloom biomass. To improve our understanding of the complex interior structure in the phycosphere, bloom samples were separated into large (>100 µm), medium (10–100 µm) and small (0.2–10 µm) size aggregates. Species richness and library coverage indicated that pyrosequencing recovered a large bacterial diversity. The community of each size aggregate was highly organized, indicating highly specific conditions within the Microcystis phycosphere. While the communities of medium and small-size aggregates clustered together in August and September samples, large- and medium-size aggregate communities in the October sample were grouped together and distinct from small-size aggregate community. Pronounced changes in the absolute and relative percentages of the dominant genus from the two most important phyla Proteobacteria and Bacteroidetes were observed among the various size aggregates. Bacterial species on large and small-size aggregates likely have the ability to degrade high and low molecular weight compounds, respectively. Thus, there exists a spatial differentiation of bacterial taxa within the phycosphere, possibly operating in sequence and synergy to catalyze the turnover of complex organic matters. PMID:25144467

Cai, Haiyuan; Jiang, Helong; Krumholz, Lee R.; Yang, Zhen

2014-01-01

15

Diversity of cyanobacterial species and phylotypes in biofilms from the littoral zone of Lake Baikal.  

PubMed

The majority of naturally occurring biofilms contain numerous microorganisms that have not yet been cultured. Additionally, there is little information available regarding the genetic structure and species diversity of these communities. Therefore, we characterised the species diversity, structure and metagenome of biofilms grown on stones and steel plates in the littoral zone of Lake Baikal (East Siberia, Russia) by applying three different approaches. First, light microscopy enabled identification of the species diversity of biofilm-forming cyanobacteria on different substrates with the dominance of Rivularia rufescens, Tolypothrix limbata, Chamaesiphon fuscus, Ch. subglobosus, and Heteroleibleinia pusilla. Additionally, scanning electron microscopy was used to show the spatial structure of biofilms. Finally, sequence analysis of 30,660 16S rRNA clones indicated a high diversity within the biofilm communities, with the majority of the microbes being closely related to Cyanobacteria (8-46% sequences), Proteobacteria (14-43%), and Bacteroidetes (10-41%). Rivularia sp., Pseudanabaena sp., and Chamaesiphon spp. were the dominant cyanobacterial phylotypes. PMID:24385352

Sorokovikova, Ekaterina G; Belykh, Olga I; Gladkikh, Anna S; Kotsar, Oleg V; Tikhonova, Irina V; Timoshkin, Oleg A; Parfenova, Valentina V

2013-12-01

16

The evolutionary species pool hypothesis and patterns of freshwater diatom  

E-print Network

the unimodal relationship between diatom species richness and lake pH within the context of the evolutionary spatial availabilities of historical pH conditions among freshwater lakes. We also determine whether local that occurred in at least 10 of the 234 lakes, four different measures of PSPs were calculated along the pH

Pither, Jason

17

Hydrogen isotope fractionation in freshwater algae: I. Variations among lipids and species  

E-print Network

Hydrogen isotope fractionation in freshwater algae: I. Variations among lipids and species Zhaohui Abstract Five species of freshwater green algae, including three strains of Botryococcus braunii (two in the algae, including alkadienes, botryococcenes, heptadecenes, fatty acids, and phytadiene, were measured

Sachs, Julian P.

18

Status, Alert System, and Prediction of Cyanobacterial Bloom in South Korea  

PubMed Central

Bloom-forming freshwater cyanobacterial genera pose a major ecological problem due to their ability to produce toxins and other bioactive compounds, which can have important implications in illnesses of humans and livestock. Cyanobacteria such as Microcystis, Anabaena, Oscillatoria, Phormidium, and Aphanizomenon species producing microcystins and anatoxin-a have been predominantly documented from most South Korean lakes and reservoirs. With the increase in frequency of such blooms, various monitoring approaches, treatment processes, and prediction models have been developed in due course. In this paper we review the field studies and current knowledge on toxin producing cyanobacterial species and ecological variables that regulate toxin production and bloom formation in major rivers (Han, Geum, Nakdong, and Yeongsan) and reservoirs in South Korea. In addition, development of new, fast, and high-throughput techniques for effective monitoring is also discussed with cyanobacterial bloom advisory practices, current management strategies, and their implications in South Korean freshwater bodies. PMID:25705675

Srivastava, Ankita; Ahn, Chi-Yong; Asthana, Ravi Kumar; Lee, Hyung-Gwan; Oh, Hee-Mock

2015-01-01

19

Ecotoxicological effects of selected cyanobacterial secondary metabolites a short review  

SciTech Connect

Cyanobacteria are one of the most diverse groups of gram-negative photosynthetic prokaryotes. Many of them are able to produce a wide range of toxic secondary metabolites. These cyanobacterial toxins can be classified in five different groups: hepatotoxins, neurotoxins, cytotoxins, dermatotoxins, and irritant toxins (lipopolysaccharides). Cyanobacterial blooms are hazardous due to this production of secondary metabolites and endotoxins, which could be toxic to animals and plants. Many of the freshwater cyanobacterial blooms include species of the toxigenic genera Microcystis, Anabaena, or Plankthotrix. These compounds differ in mechanisms of uptake, affected organs, and molecular mode of action. In this review, the main focus is the aquatic environment and the effects of these toxins to the organisms living there. Some basic toxic mechanisms will be discussed in comparison to the mammalian system.

Wiegand, C. [Leibniz Institute of Freshwater Ecology and Inland Fisheries, Mueggelseedamm 301, 12587 Berlin (Germany)]. E-mail: cwiegand@igb-berlin.de; Pflugmacher, S. [Leibniz Institute of Freshwater Ecology and Inland Fisheries, Mueggelseedamm 301, 12587 Berlin (Germany)]. E-mail: pflugmacher@igb-berlin.de

2005-03-15

20

Can the Cyanobacterial Carbon-Concentrating Mechanism Increase Photosynthesis in Crop Species? A Theoretical Analysis1[W][OPEN  

PubMed Central

Experimental elevation of [CO2] around C3 crops in the field has been shown to increase yields by suppressing the Rubisco oxygenase reaction and, in turn, photorespiration. Bioengineering a cyanobacterial carbon-concentrating mechanism (CCM) into C3 crop species provides a potential means of elevating [CO2] at Rubisco, thereby decreasing photorespiration and increasing photosynthetic efficiency and yield. The cyanobacterial CCM is an attractive alternative relative to other CCMs, because its features do not require anatomical changes to leaf tissue. However, the potential benefits of engineering the entire CCM into a C3 leaf are unexamined. Here, a CO2 and HCO3? diffusion-reaction model is developed to examine how components of the cyanobacterial CCM affect leaf light-saturated CO2 uptake (Asat) and to determine whether a different Rubisco isoform would perform better in a leaf with a cyanobacterial CCM. The results show that the addition of carboxysomes without other CCM components substantially decreases Asat and that the best first step is the addition of HCO3? transporters, as a single HCO3? transporter increased modeled Asat by 9%. Addition of all major CCM components increased Asat from 24 to 38 µmol m?2 s?1. Several Rubisco isoforms were compared in the model, and increasing ribulose bisphosphate regeneration rate will allow for further improvements by using a Rubisco isoform adapted to high [CO2]. Results from field studies that artificially raise [CO2] suggest that this 60% increase in Asat could result in a 36% to 60% increase in yield. PMID:24550242

McGrath, Justin M.; Long, Stephen P.

2014-01-01

21

Supplementary Information Species Optimal N:P Freshwater/ Taxon Source  

E-print Network

Cyanobacterium 8 Heterosigma akashiwo 13.1 Marine Rhaphydophyte 9 Anabaena solitaria 14.0 Freshwater Coccolithophorid 11 Oscillatoria redekei 17.1 Freshwater Cyanobacterium 8 Anabaena flos-aquae 17.7 Freshwater

22

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

PubMed

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

2011-10-01

23

Nitrogen Forms Influence Microcystin Concentration and Composition via Changes in Cyanobacterial Community Structure  

PubMed Central

The eutrophication of freshwaters is a global health concern as lakes with excess nutrients are often subject to toxic cyanobacterial blooms. Although phosphorus is considered the main element regulating cyanobacterial biomass, nitrogen (N) concentration and more specifically the availability of different N forms may influence the overall toxicity of blooms. In this study of three eutrophic lakes prone to cyanobacterial blooms, we examined the effects of nitrogen species and concentrations and other environmental factors in influencing cyanobacterial community structure, microcystin (MC) concentrations and MC congener composition. The identification of specific MC congeners was of particular interest as they vary widely in toxicity. Different nitrogen forms appeared to influence cyanobacterial community structure leading to corresponding effects on MC concentrations and composition. Total MC concentrations across the lakes were largely explained by a combination of abiotic factors: dissolved organic nitrogen, water temperature and ammonium, but Microcystis spp. biomass was overall the best predictor of MC concentrations. Environmental factors did not appear to affect MC congener composition directly but there were significant associations between specific MC congeners and particular species. Based on redundancy analyses (RDA), the relative biomass of Microcystis aeruginosa was associated with MC-RR, M. wesenbergii with MC-LA and Aphanizomenon flos-aquae with MC-YR. The latter two species are not generally considered capable of MC production. Total nitrogen, water temperature, ammonium and dissolved organic nitrogen influenced the cyanobacterial community structure, which in turn resulted in differences in the dominant MC congener and the overall toxicity. PMID:24427318

Monchamp, Marie-Eve; Pick, Frances R.; Beisner, Beatrix E.; Maranger, Roxane

2014-01-01

24

Nitrogen forms influence microcystin concentration and composition via changes in cyanobacterial community structure.  

PubMed

The eutrophication of freshwaters is a global health concern as lakes with excess nutrients are often subject to toxic cyanobacterial blooms. Although phosphorus is considered the main element regulating cyanobacterial biomass, nitrogen (N) concentration and more specifically the availability of different N forms may influence the overall toxicity of blooms. In this study of three eutrophic lakes prone to cyanobacterial blooms, we examined the effects of nitrogen species and concentrations and other environmental factors in influencing cyanobacterial community structure, microcystin (MC) concentrations and MC congener composition. The identification of specific MC congeners was of particular interest as they vary widely in toxicity. Different nitrogen forms appeared to influence cyanobacterial community structure leading to corresponding effects on MC concentrations and composition. Total MC concentrations across the lakes were largely explained by a combination of abiotic factors: dissolved organic nitrogen, water temperature and ammonium, but Microcystis spp. biomass was overall the best predictor of MC concentrations. Environmental factors did not appear to affect MC congener composition directly but there were significant associations between specific MC congeners and particular species. Based on redundancy analyses (RDA), the relative biomass of Microcystis aeruginosa was associated with MC-RR, M. wesenbergii with MC-LA and Aphanizomenon flos-aquae with MC-YR. The latter two species are not generally considered capable of MC production. Total nitrogen, water temperature, ammonium and dissolved organic nitrogen influenced the cyanobacterial community structure, which in turn resulted in differences in the dominant MC congener and the overall toxicity. PMID:24427318

Monchamp, Marie-Eve; Pick, Frances R; Beisner, Beatrix E; Maranger, Roxane

2014-01-01

25

Mercury toxicity to freshwater organisms: extrapolation using species sensitivity distribution.  

PubMed

Mercury toxicity to aquatic organisms was evaluated in different taxonomic groups showing the following species sensitivity gradient: Daphnia magna > Daphnia longispina > Pseudokirchneriella subcapitata > Chlorella vulgaris > Lemna minor > Chironomus riparius. Toxicity values ranged from 3.49 ?g/L (48 h-EC?? of D. magna) to 1.58 mg/L (48 h-EC?? of C. riparius). A species sensitivity distribution was used to estimate hazardous mercury concentration at 5 % level (HC5) and the predicted no effect concentration (PNEC). The HC5 was 3.18 ?g Hg/L and the PNEC varied between 0.636 and 3.18 ?g Hg/L, suggesting no risk of acute toxicity to algae, plants, crustaceans and insects in most freshwaters. PMID:23771310

Rodrigues, Andreia C M; Jesus, Fátima T; Fernandes, Marco A F; Morgado, Fernando; Soares, Amadeu M V M; Abreu, Sizenando N

2013-08-01

26

Selenium species and their distribution in freshwater fish from Argentina.  

PubMed

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

2013-02-01

27

Abstract Over 70% of North American freshwater mussel species (families Unionidae and Margaritiferi-  

E-print Network

and/or highly vagile fish hosts for this species. Genetic structure in the Lake Erie drainageAbstract Over 70% of North American freshwater mussel species (families Unionidae and Margaritiferi for investiga- tions of freshwater mussel population genetics. Using mtDNA and allozymes, we determined

Vaughn, Caryn

28

Rare and endangered species: freshwater gastropods of southern New England  

SciTech Connect

The rare and endangered species of freshwater gastropods of southern New England are reported on based upon data collected over the past four years. Field sampling was concentrated in Connecticut but included parts of southern Massachusetts east to Cape Code (69 55 W to 73 45'W, 40 00'N). Water chemistry data were collected along with the snails. Collection methods and water analysis techniques have been described elsewhere by Jokinen (The Nautilus 92:156-160, 1978). Voucher specimens have been placed in the Museum of Comparative Zoology, Harvard University, The Florida State Museum, and the Museum of Zoology, the University of Michigan. Acid rain poses a threat to poorly buffered habitats. 6 references, 1 table.

Jokinen, E.H.; Pondick, J.

1981-01-01

29

Complex hydraulic and substrate variables limit freshwater mussel species richness and abundance  

E-print Network

Complex hydraulic and substrate variables limit freshwater mussel species richness and abundance. We examined how substrate and complex hydraulic variables limit the distribution of freshwater mussels. We sampled mussels and measured substrate and hydraulic variables (at low and high flows) at 6

Vaughn, Caryn

30

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

2004-01-01

31

Spatial Distribution of Cryptic Species Diversity in European Freshwater Amphipods (Gammarus fossarum)  

E-print Network

Spatial Distribution of Cryptic Species Diversity in European Freshwater Amphipods (Gammarus important stream amphipod Gammarus fossarum (types A, B and C). We use a novel pyrosequencing assay Diversity in European Freshwater Amphipods (Gammarus fossarum) as Revealed by Pyrosequencing. PLoS ONE 6

32

Freshwater availability and coastal wetland foundation species: ecological transitions along a rainfall gradient  

USGS Publications Warehouse

Climate gradient-focused ecological research can provide a foundation for better understanding critical ecological transition points and nonlinear climate-ecological relationships, which is information that can be used to better understand, predict, and manage ecological responses to climate change. In this study, we examined the influence of freshwater availability upon the coverage of foundation plant species in coastal wetlands along a northwestern Gulf of Mexico rainfall gradient. Our research addresses the following three questions: (1) what are the region-scale relationships between measures of freshwater availability (e.g., rainfall, aridity, freshwater inflow, salinity) and the relative abundance of foundation plant species in tidal wetlands; (2) How vulnerable are foundation plant species in tidal wetlands to future changes in freshwater availability; and (3) What is the potential future relative abundance of tidal wetland foundation plant species under alternative climate change scenarios? We developed simple freshwater availability-based models to predict the relative abundance (i.e., coverage) of tidal wetland foundation plant species using climate data (1970-2000), estuarine freshwater inflow-focused data, and coastal wetland habitat data. Our results identify regional ecological thresholds and nonlinear relationships between measures of freshwater availability and the relative abundance of foundation plant species in tidal wetlands. In drier coastal zones, relatively small changes in rainfall could produce comparatively large landscape-scale changes in foundation plant species abundance which would affect some ecosystem good and services. Whereas a drier future would result in a decrease in the coverage of foundation plant species, a wetter future would result in an increase in foundation plant species coverage. In many ways, the freshwater-dependent coastal wetland ecological transitions we observed are analogous to those present in dryland terrestrial ecosystems.

Osland, Michael; Enwright, Nicholas; Stagg, Camille La Fosse

2014-01-01

33

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

2005-01-01

34

CONDITIONS FOR COEXISTENCE OF FRESHWATER MUSSEL SPECIES VIA PARTITIONING OF FISH HOST RESOURCES  

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...

35

Why are there so few freshwater fish species in most estuaries?  

PubMed

The freshwater fish assemblage in most estuaries is not as species rich as the marine assemblage in the same systems. Coupled with this differential richness is an apparent inability by most freshwater fish species to penetrate estuarine zones that are mesohaline (salinity: 5·0-17·9), polyhaline (salinity: 18·0-29·9) or euhaline (salinity: 30·0-39·9). The reason why mesohaline waters are avoided by most freshwater fishes is difficult to explain from a physiological perspective as many of these species would be isosmotic within this salinity range. Perhaps, a key to the poor penetration of estuarine waters by freshwater taxa is an inability to develop chloride cells in gill filament epithelia, as well as a lack of other osmoregulatory adaptations present in euryhaline fishes. Only a few freshwater fish species, especially some of those belonging to the family Cichlidae, have become fully euryhaline and have successfully occupied a wide range of estuaries, sometimes even dominating in hyperhaline systems (salinity 40+). Indeed, this review found that there are few fish species that can be termed holohaline (i.e. capable of occupying waters with a salinity range of 0-100+) and, of these taxa, there is a disproportionally high number of freshwater species (e.g. Cyprinodon variegatus, Oreochromis mossambicus and Sarotherodon melanotheron). Factors such as increased competition for food and higher predation rates by piscivorous fishes and birds may also play an important role in the low species richness and abundance of freshwater taxa in estuaries. Added to this is the relatively low species richness of freshwater fishes in river catchments when compared with the normally higher diversity of marine fish species for potential estuarine colonization from the adjacent coastal waters. The almost complete absence of freshwater fish larvae from the estuarine ichthyoplankton further reinforces the poor representation of this guild within these systems. An explanation as to why more freshwater fish species have not become euryhaline and occupied a wide range of estuaries similar to their marine counterparts is probably due to a combination of the above described factors, with physiological restrictions pertaining to limited salinity tolerances probably playing the most important role. PMID:25739335

Whitfield, A K

2015-04-01

36

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. PMID:22977349

Glöer, Peter; Peši?, Vladimir

2012-01-01

37

Is PCBs concentration variability between and within freshwater fish species explained by their contamination pathways?  

Microsoft Academic Search

Many chemical, physiological, and trophic factors are known to affect bioaccumulation of polychlorinated biphenyls (PCBs) in biota. Understanding the primary factors affecting fish contamination is critical for predicting and assessing risks to upper-trophic level consumers, including humans. Here we identify PCB contamination pathways that could explain within- and between-species variability in fish concentration levels. Three freshwater river fish species (barbel,

C. Lopes; M.-E. Perga; A. Peretti; M.-C. Roger; H. Persat; M. Babut

2011-01-01

38

A revision of the species of Bothriocephalus Rudolphi, 1808 (Cestoda: Pseudophyllidea) parasitic in American freshwater fishes  

Microsoft Academic Search

The species of the pseudophyllidean genus Bothriocephalus Rudolphi, 1808 parasitising freshwater fishes in America are revised, based on the examination of type and voucher specimens of seven taxa. There are five valid species: Bothriocephalus claviceps (Goeze, 1782), B. cuspidatus Cooper, 1917, B. formosus Mueller & Van Cleave, 1932, B. acheilognathi Yamaguti, 1934, and B. pearsei Scholz, Vargas-Vázquez & Moravec, 1996.

Tomáš Scholz

1997-01-01

39

Avian vacuolar myelinopathy linked to exotic aquatic plants and a novel cyanobacterial species  

Microsoft Academic Search

Invasions of exotic species have created environmental havoc through competition and dis- placement of native plants and animals. The introduction of hydrilla (Hydrilla verticillata) into the United States in the 1960s has been detrimental to navigation, power generation, water intake, and water quality (McCann et al., 1996). Our field surveys and feeding studies have now implicated exotic hydrilla and asso-

Susan B. Wilde; Thomas M. Murphy; Charlotte P. Hope; Sarah K. Habrun; Jason Kempton; Anna Birrenkott; Faith Wiley; William W. Bowerman; Alan J. Lewitus

2005-01-01

40

Gasification of cyanobacterial in supercritical water.  

PubMed

Cyanobacterial collected from eutrophic freshwater lakes constituted intractable waste with a rich algae biomass content. Supercritical water gasification (SCWG) was proposed to treat the cyanobacterial and to produce hydrogen for energy. The H 2 yield reached 2.92 mol/kg at reaction conditions of 500 °C, 30 min and 22 MPa; this yield accounted for 26% of the total gaseous products. Abundant ammonia and dissolved reactive phosphorous were concentrated in the liquid product, which could be recovered and used as a liquid fertilizer. Solid residue, which accounted only for about 1% of the wet weight, was mainly composed of coke and ash. The efficiency of H 2 production was better than that from other biomass, because of the abundant organic matter in cyanobacterial. Thus, cyanobacterial are an ideal biomass feedstock for H 2 production from SCWG. PMID:25176482

Zhang, Huiwen; Zhu, Wei; Xu, Zhirong; Gong, Miao

2014-01-01

41

Cyanobacterial chemical warfare affects zooplankton community composition  

Microsoft Academic Search

SUMMARY 1. Toxic algal blooms widely affect our use of water resources both with respect to drinking water and recreation. However, it is not only humans, but also organisms living in freshwater and marine ecosystems that may be affected by algal toxins. 2. In order to assess if cyanobacterial toxins affect the composition of natural zooplankton communities, we quantified the

LARS-ANDERS HANSSON; SUSANNE GUSTAFSSON; KARIN RENGEFORS; LINA BOMARK

2007-01-01

42

Regulation of gene expression in diverse cyanobacterial species by using theophylline-responsive riboswitches.  

PubMed

Cyanobacteria are photosynthetic bacteria that are currently being developed as biological production platforms. They derive energy from light and carbon from atmospheric carbon dioxide, and some species can fix atmospheric nitrogen. One advantage of developing cyanobacteria for renewable production of biofuels and other biological products is that they are amenable to genetic manipulation, facilitating bioengineering and synthetic biology. To expand the currently available genetic toolkit, we have demonstrated the utility of synthetic theophylline-responsive riboswitches for effective regulation of gene expression in four diverse species of cyanobacteria, including two recent isolates. We evaluated a set of six riboswitches driving the expression of a yellow fluorescent protein reporter in Synechococcus elongatus PCC 7942, Leptolyngbya sp. strain BL0902, Anabaena sp. strain PCC 7120, and Synechocystis sp. strain WHSyn. We demonstrated that riboswitches can offer regulation of gene expression superior to that of the commonly used isopropyl-?-d-thiogalactopyranoside induction of a lacI(q)-Ptrc promoter system. We also showed that expression of the toxic protein SacB can be effectively regulated, demonstrating utility for riboswitch regulation of proteins that are detrimental to biomass accumulation. Taken together, the results of this work demonstrate the utility and ease of use of riboswitches in the context of genetic engineering and synthetic biology in diverse cyanobacteria, which will facilitate the development of algal biotechnology. PMID:25149516

Ma, Amy T; Schmidt, Calvin M; Golden, James W

2014-11-01

43

Characterization factors for water consumption and greenhouse gas emissions based on freshwater fish species extinction.  

PubMed

Human-induced changes in water consumption and global warming are likely to reduce the species richness of freshwater ecosystems. So far, these impacts have not been addressed in the context of life cycle assessment (LCA). Here, we derived characterization factors for water consumption and global warming based on freshwater fish species loss. Calculation of characterization factors for potential freshwater fish losses from water consumption were estimated using a generic species-river discharge curve for 214 global river basins. We also derived characterization factors for potential freshwater fish species losses per unit of greenhouse gas emission. Based on five global climate scenarios, characterization factors for 63 greenhouse gas emissions were calculated. Depending on the river considered, characterization factors for water consumption can differ up to 3 orders of magnitude. Characterization factors for greenhouse gas emissions can vary up to 5 orders of magnitude, depending on the atmospheric residence time and radiative forcing efficiency of greenhouse gas emissions. An emission of 1 ton of CO? is expected to cause the same impact on potential fish species disappearance as the water consumption of 10-1000 m³, depending on the river basin considered. Our results make it possible to compare the impact of water consumption with greenhouse gas emissions. PMID:21574555

Hanafiah, Marlia M; Xenopoulos, Marguerite A; Pfister, Stephan; Leuven, Rob S E W; Huijbregts, Mark A J

2011-06-15

44

SHORT-TERM TOXICITY OF FIVE OIL S TO FOUR FRESHWATER SPECIES  

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...

45

The Asian Fish Tapeworm Bothriocephalus acheilognathi : a Potential Threat to Native Freshwater Fish Species in Mexico  

Microsoft Academic Search

Introduction of the parasite Bothriocephalus acheilognathi Yamaguti, 1934 with the herbivorous carp Ctenopharyngodon idellus, and other cyprinids, has been documented in almost every continent, except Antarctica. This study presents the current geographical distribution of this cestode in the freshwater fish of Mexico, highlighting infections in autochthonous and endemic species. It compiles existing information and presents original data. B. acheilognathi is

Guillermo Salgado-Maldonado; Raúl F. Pineda-López

2003-01-01

46

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. PMID:22038598

Zeng, Jin; Bian, Yuanqi; Xing, Peng

2012-01-01

47

Toxicity of arsenic species to three freshwater organisms and biotransformation of inorganic arsenic by freshwater phytoplankton (Chlorella sp. CE-35).  

PubMed

In the environment, arsenic (As) exists in a number of chemical species, and arsenite (As(III)) and arsenate (As(V)) dominate in freshwater systems. Toxicity of As species to aquatic organisms is complicated by their interaction with chemicals in water such as phosphate that can influence the bioavailability and uptake of As(V). In the present study, the toxicities of As(III), As(V) and dimethylarsinic acid (DMA) to three freshwater organisms representing three phylogenetic groups: a phytoplankton (Chlorella sp. strain CE-35), a floating macrophyte (Lemna disperma) and a cladoceran grazer (Ceriodaphnia cf. dubia), were determined using acute and growth inhibition bioassays (EC??) at a range of total phosphate (TP) concentrations in OECD medium. The EC?? values of As(III), As(V) and DMA were 27 ± 10, 1.15 ± 0.04 and 19 ± 3 mg L(-1) for Chlorella sp. CE-35; 0.57 ± 0.16, 2.3 ± 0.2 and 56 ± 15 mg L(-1) for L. disperma, and 1.58 ± 0.05, 1.72 ± 0.01 and 5.9 ± 0.1 mg L(-1) for C. cf. dubia, respectively. The results showed that As(III) was more toxic than As(V) to L. disperma; however, As(V) was more toxic than As(III) to Chlorella sp. CE-35. The toxicities of As(III) and As(V) to C. cf. dubia were statistically similar (p>0.05). DMA was less toxic than iAs species to L. disperma and C. cf. dubia, but more toxic than As(III) to Chlorella sp. CE-35. The toxicity of As(V) to Chlorella sp. CE-35 and L. disperma decreased with increasing TP concentrations in the growth medium. Phosphate concentrations did not influence the toxicity of As(III) to either organism. Chlorella sp. CE-35 showed the ability to reduce As(V) to As(III), indicating a substantial influence of phytoplankton on As biogeochemistry in freshwater aquatic systems. PMID:24836887

Rahman, M Azizur; Hogan, Ben; Duncan, Elliott; Doyle, Christopher; Krassoi, Rick; Rahman, Mohammad Mahmudur; Naidu, Ravi; Lim, Richard P; Maher, William; Hassler, Christel

2014-08-01

48

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

PubMed

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

2005-01-01

49

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

2010-01-01

50

Mitochondrial DNA identification of game and harvested freshwater fish species  

Microsoft Academic Search

The use of DNA in forensics has grown rapidly for human applications along with the concomitant development of bioinformatics and demographic databases to help fully realize the potential of this molecular information. Similar techniques are also used routinely in many wildlife cases, such as species identification in food products, poaching and the illegal trade of endangered species. The use of

C. J. Kyle; C. C. Wilson

2007-01-01

51

Using remote underwater video to estimate freshwater fish species richness.  

PubMed

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

2013-05-01

52

Conditions for coexistence of freshwater mussel species via partitioning of fish host resources  

USGS Publications Warehouse

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 larval stage may promote coexistence. A model of resource utilization was developed for two mussel species and analyzed to determine conditions for coexistence. Mussel species were predicted to coexist when they differed in terms of their success in contacting different fish host species; very similar strategies offered limited possibilities for coexistence. Differences in the mussel species' maximum infestation loads on the fish hosts that coincided with differences in their fish host contact success promoted coexistence. Mussel species with a given set of trade-offs in fish host use were predicted to coexist only for a subset of relative fish host abundances, so a shift in relative fish host abundances could result in the loss of a mussel species. An understanding of the conditions for freshwater mussel species coexistence can help explain high mussel diversity in rivers and guide ongoing conservation activities. ?? 2006 Elsevier B.V. All rights reserved.

Rashleigh, B.; DeAngelis, D.L.

2007-01-01

53

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.

2005-05-01

54

Environmental heterogeneity predicts species richness of freshwater mollusks in sub-Saharan Africa  

NASA Astrophysics Data System (ADS)

Species diversity and how it is structured on a continental scale is influenced by stochastic, ecological, and evolutionary driving forces, but hypotheses on determining factors have been mainly examined for terrestrial and marine organisms. The extant diversity of African freshwater mollusks is in general well assessed to facilitate conservation strategies and because of the medical importance of several taxa as intermediate hosts for tropical parasites. This historical accumulation of knowledge has, however, not resulted in substantial macroecological studies on the spatial distribution of freshwater mollusks. Here, we use continental distribution data and a recently developed method of random and cohesive allocation of species distribution ranges to test the relative importance of various factors in shaping species richness of Bivalvia and Gastropoda. We show that the mid-domain effect, that is, a hump-shaped richness gradient in a geographically bounded system despite the absence of environmental gradients, plays a minor role in determining species richness of freshwater mollusks in sub-Saharan Africa. The western branch of the East African Rift System was included as dispersal barrier in richness models, but these simulation results did not fit observed diversity patterns significantly better than models where this effect was not included, which suggests that the rift has played a more complex role in generating diversity patterns. Present-day precipitation and temperature explain richness patterns better than Eemian climatic condition. Therefore, the availability of water and energy for primary productivity during the past does not influence current species richness patterns much, and observed diversity patterns appear to be in equilibrium with contemporary climate. The availability of surface waters was the best predictor of bivalve and gastropod richness. Our data indicate that habitat diversity causes the observed species-area relationship, and hence, that environmental heterogeneity is a principal driver of freshwater mollusk richness on a continental scale.

Hauffe, T.; Schultheiß, R.; Van Bocxlaer, B.; Prömmel, K.; Albrecht, C.

2014-12-01

55

Belize, a country rich in natural resources and diverse wildlife, is home to nine species of freshwater  

E-print Network

of freshwater turtles. Among these is the critically endangered hicatee, which has been eliminated in most of its range as a result of hunting and habitat loss. Freshwater turtles live in rivers, creeks. However, little is known about Belize's unique turtle species. We hope that this guide will help people

Mazzotti, Frank

56

Importance of hybridization between indigenous and nonindigenous freshwater species: an overlooked threat to North American biodiversity.  

PubMed

Biodiversity of North American freshwaters is among the greatest in the world. However, due to extensive habitat degradation, pollution, and introductions of nonindigenous species, this biodiversity is also among the most endangered. Unlike habitat degradation and pollution, nonindigenous species represent a permanent loss of biodiversity because their removal or control is often impossible. Most species introduced into nonnative North American ranges, however, are not from Eurasia but have been introduced from geographically isolated regions within North America. Although the ecological effects of introduced species have been widely documented, the effects of hybridization, especially between closely related species, represents an equally serious mechanism of extinction but is much less studied. Identification of which species are likely to hybridize after contact is of critical importance to prevent the further loss of native species. Molecular phylogenetics serves as a powerful tool to identify freshwater species at risk of introgression, if we can assume that genetic distance is a good predictor of the potential for hybridization. Although not a thorough review of all cases of hybridization, this article documents the extent and effects of hybridization in fishes, crayfishes, mussels, and other invertebrates in light of the currently accepted phylogenetic relationships. We suggest this approach may be the first step in addressing the potential threat of hybridization between many of the closely related species in North American fresh waters. PMID:12028732

Perry, William L; Lodge, David M; Feder, Jeffrey L

2002-04-01

57

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. PMID:21857936

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

2011-01-01

58

Concentrations of microcystins in tissues of several fish species from freshwater reservoirs and ponds.  

PubMed

The aim of this study is to summarise the determination of concentrations of microcystins (MCs) in muscle and liver of freshwater fish species caught in stagnant waters of the Czech Republic. Within the years 2007-2009, 351 muscle samples and 291 liver samples of 16 freshwater fish species derived from four fishponds, and four water reservoirs were analysed. MCs were detected in 53 liver samples. The highest concentrations of microcystins were determined in liver samples of carnivorous fish species; 50.3 ng/g of fresh weight (FW) in perch (Perca fluviatilis) and 22.7 ng/g FW in pikeperch (Sander lucioperca). MCs in liver were detected in other five fish species; asp (Aspius aspius), pike (Esox lucius), common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella) and European eel (Anguilla anguilla). Concentrations of MCs in liver of nine fish species (European bream, whitefish, tench, silver carp, European catfish, roach, chub, crucian carp and rudd) were below the detection limit of 1.2-5.4 ng/g FW for different MC congeners. However, the concentrations of MCs in all muscle samples were below the detection limit. The assessment of MCs concentrations might be influenced by the detection method used. Due to the concentrations of MCs being below the detection limit in muscle samples of all fish species analysed, it seems that there might be a low potential threat for human health in case of fish muscle consumption. PMID:23756815

Kopp, Radovan; Palíková, Miroslava; Adamovský, Ond?ej; Ziková, Andrea; Navrátil, Stanislav; Kohoutek, Ji?í; Mareš, Jan; Bláha, Lud?k

2013-12-01

59

Descriptions of two new freshwater neotropical species of Rhinebothrium (Cestoda: Rhinebothriidea) from Potamotrygon motoro (Chondrichthyes: Potamotrygonidae).  

PubMed

Two new species of Rhinebothrium (Cestoda, Rhinebothriidea) from potamotrygonid stingrays in the Neotropical region are herein described, which raises the total number of Rhinebothrium species known from Neotropical freshwaters to five. Rhinebothrium corbatai sp. n., and Rhinebothrium mistyae sp. n. were both collected from Potamotrygon motoro (Müller et Henle), captured in four tributaries of the Paraná River in Santa Fé Province, Argentina. The new species can be distinguished from their congeners, and from each other, by a combination of various features, including worm size (length and number of proglottids), number of loculi per bothridium, microthrix pattern, size of the cirrus sac, and the extent of the vas deferens. The discovery of these new species from P. motoro supports the pattern of high host specificity in this cestode genus, and reinforces the notion that some of the previous records of the enigmatic R. paratrygoni may correspond to new species of Rhinebothrium yet to be described. PMID:22053615

Menoret, Adriana; Ivanov, Verónica A

2011-09-01

60

Acute toxicity and effects analysis of endosulfan sulfate to freshwater fish species.  

PubMed

Endosulfan sulfate is a persistent environmental metabolite of endosulfan, an organochlorine insecticide-acaricide presently registered by the United States Environmental Protection Agency. There is, however, limited acute fish toxicity data for endosulfan sulfate. This study determines the acute toxicity (LC??s and LC??s) of endosulfan sulfate to three inland Florida native fish species (mosquitofish [Gambusia affinis]; least killifish [Heterandria formosa]; and sailfin mollies [Poecilia latipinna]) as well as fathead minnows (Pimephales promelas). Ninety-six-h acute toxicity tests were conducted with each fish species under flow-through conditions. For all of the above-mentioned fish species, 96-h LC?? estimates ranged from 2.1 to 3.5 ?g/L endosulfan sulfate. The 96-h LC?? estimates ranged from 0.8 to 2.1 ?g/L endosulfan sulfate. Of all of the fish tested, the least killifish appeared to be the most sensitive to endosulfan sulfate exposure. The above-mentioned data were combined with previous acute toxicity data for endosulfan sulfate and freshwater fish for an effects analysis. The effects analysis estimated hazardous concentrations expected to exceed 5, 10, and 50% of the fish species' acute LC?? or LC?? values (HC?, HC??, and HC??). The endosulfan sulfate freshwater-fish acute tests were also compared with the available freshwater-fish acute toxicity data for technical endosulfan. Technical endosulfan is a mixture of ?- and ?-endosulfan. The LC??s had a wider range for technical endosulfan, and their distribution produced a lower HC?? than for endosulfan sulfate. The number of freshwater-fish LC??s for endosulfan sulfate is much smaller than the number available for technical endosulfan, reflecting priorities in examining the toxicity of the parent compounds of pesticides. The toxicity test results and effects analyses provided acute effect values for endosulfan sulfate and freshwater fish that might be applied in future screening level ecologic risk assessments. The effects analyses also discussed several deficiencies in conventional methods for setting water-quality criteria and determining ecologic effects from acute toxicity tests. PMID:21127850

Carriger, John F; Hoang, Tham C; Rand, Gary M; Gardinali, Piero R; Castro, Joffre

2011-02-01

61

Water temperature: A factor in the seasonality of two freshwater sponge species, Ephydatia fluviatilis and Spongilla alba  

Microsoft Academic Search

Two freshwater sponge species, Ephvdatia fluviatilis and Spongilla alba, were maintained in a continuous-flow laboratory culture system at several different water temperatures. Experimental results suggest that sponge growth rate is affected by water temperature and that it is affected differently in the two species. The results correlate well with field observations on species abundance at different water temperatures and thereby

R. E. Harsha; J. C. Francis; M. A. Poirrier

1983-01-01

62

Accumulation and elimination of chromium by freshwater species exposed to spiked sediments.  

PubMed

The bioaccumulation and elimination capacity of chromium were examined in four freshwater species: the submersed aquatic plant Ceratophyllum demersum (Ceratophyllaceae), the oligochaete Limnodrilus udekemianus (Tubificidae), the crab Zilchiopsis collastinensis (Decapoda), and the fish Cnesterodon decemmaculatus (Poeciliidae). All of the species were exposed simultaneously to sediments spiked with Cr (K(2)Cr(2)O(7)) at different concentrations for 28 days, followed by 7 days without Cr to evaluate the concentration of residual Cr. We found that Cr accumulated in the tissues of all four species. The highest bioconcentration factor obtained for each species is as follows: C. demersum, 718.66 (+/-272.91); L. udekemianus, 172.55 (+/-80.8), Z. collastinensis, 67.72 (+/-35.4); C. decemmaculatus, 23.11 (+/-12.82), all at 28 days of exposure. PMID:18274820

Marchese, Mercedes; Gagneten, Ana M; Parma, María J; Pavé, Paola J

2008-11-01

63

Effect of glyphosate on growth of four freshwater species of phytoplankton: a microplate bioassay.  

PubMed

The acute toxicity of glyphosate herbicide was tested on the four species of freshwater phytoplankton, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila. Herbicide concentrations eliciting a 50% growth reduction over 72 h (EC(50)) ranged from 24.5 to 41.7 mg L(-1), whilst a 10% growth inhibition is achieved by herbicide concentrations ranging from 1.6 to 3.0 mg L(-1), difficult to find neither in paddy fields (it is not used in rice) nor in the lake of the Albufera Natural Park. Chorella species are less sensitive to the herbicide than Scenedesmus species. It can be concluded that glyphosate has a low potential risk for the tested organisms. PMID:19266135

Vendrell, E; Ferraz, D Gómez de Barreda; Sabater, C; Carrasco, J M

2009-05-01

64

Fish species introductions provide novel insights into the patterns and drivers of phylogenetic structure in freshwaters.  

PubMed

Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. PMID:24452027

Strecker, Angela L; Olden, Julian D

2014-03-01

65

Fish species introductions provide novel insights into the patterns and drivers of phylogenetic structure in freshwaters  

PubMed Central

Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. PMID:24452027

Strecker, Angela L.; Olden, Julian D.

2014-01-01

66

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

1999-01-01

67

The occurrence of an Australian leech species (genus Helobdella) in German freshwater habitats as revealed by mitochondrial DNA sequences  

Microsoft Academic Search

The freshwater leech Helobdella europaea Kutschera 1987 was discovered twenty years ago in Germany and described as a new species. Here, we show that this leech is genetically identical with the Australian species Helobdella papillornata (CO-I-mt-DNA sequence identity of alignment positions: 98%). We conclude that H. europaea (syn. H. papillornata) represents an introduced annelid that occupies the same ecological niche

I. Pfeiffer; B. Brenig; U. Kutschera

2004-01-01

68

Heterogeneity of Alkane Chain Length in Freshwater and Marine Cyanobacteria  

PubMed Central

The potential utilization of cyanobacteria for the biological production of alkanes represents an exceptional system for the next generation of biofuels. Here, we analyzed a diverse group of freshwater and marine cyanobacterial isolates from Indian culture collections for their ability to produce both alkanes and alkenes. Among the 50 cyanobacterial isolates screened, 32 isolates; 14 freshwater and 18 marine isolates; produced predominantly alkanes. The GC-MS/MS profiles revealed a higher percentage of pentadecane and heptadecane production for marine and freshwater strains, respectively. Oscillatoria species were found to be the highest producers of alkanes. Among the freshwater isolates, Oscillatoria CCC305 produced the maximum alkane level with 0.43??g/mg dry cell weight, while Oscillatoria formosa BDU30603 was the highest producer among the marine isolates with 0.13??g/mg dry cell weight. Culturing these strains under different media compositions showed that the alkane chain length was not influenced by the growth medium but was rather an inherent property of the strains. Analysis of the cellular fatty acid content indicated the presence of predominantly C16 chain length fatty acids in marine strains, while the proportion of C18 chain length fatty acids increased in the majority of freshwater strains. These results correlated with alkane chain length specificity of marine and freshwater isolates indicating that alkane chain lengths may be primarily determined by the fatty acid synthesis pathway. Moreover, the phylogenetic analysis showed clustering of pentadecane-producing marine strains that was distinct from heptadecane-producing freshwater strains strongly suggesting a close association between alkane chain length and the cyanobacteria habitat.

Shakeel, Tabinda; Fatma, Zia; Fatma, Tasneem; Yazdani, Syed Shams

2015-01-01

69

Molecular markers for genetic diversity, gene flow and genetic population structure of freshwater mussel species.  

PubMed

Freshwater mussel species are in global decline. Anthropogenic changes of river channels and the decrease of autochthonous fish population, the natural hosts of mussels larval stages (glochidia), are the main causes. Therefore, the conservation of mussel species depends not only on habitat conservation, but also on the availability of the fish host. In Portugal, information concerning most of the mussel species is remarkably scarce. One of the most known species, Unio pictorum is also in decline however, in the basins of the rivers Tua and Sabor (Northeast of Portugal), there is some indication of relatively large populations. The aforementioned rivers can be extremely important for this species conservation not only in Portugal, but also in the remaining Iberian Peninsula. Thus, it is important to obtain data concerning Unio pictorum bioecology (distribution, habitat requirements, population structure, genetic variability, reproductive cycle and recruitment rates), as well as the genetic variability and structure of the population. Concomitantly, information concerning fish population structure, the importance of the different fish species as "glochidia" hosts and their appropriate density to allow effective mussel recruitment, will also be assessed. The achieved data is crucial to obtain information to develop effective management measures in order to promote the conservation of this bivalve species, the conservation of autochthonous fish populations, and consequently the integrity of the river habitats. PMID:25627381

Choupina, Ab; Martins, Im

2014-08-01

70

Genetic and morphological evidence for substantial hidden biodiversity in a freshwater crayfish species complex.  

PubMed

North America is a center of biodiversity for freshwater crayfish, with >300 described species, mostly in the family Cambaridae. However, the phylogenetic and phylogeographic relationships among these taxa are poorly understood, despite their ubiquitous occurrence in North American freshwater habitats. Here, we target the geographically widespread Orconectesvirilis and its sister taxa for genetic and morphological investigation. We used sequence data from two mitochondrial genes (16S rRNA and cytochrome oxidase I) and from one nuclear gene (glyceraldehyde-3-phosphate dehydrogenase), as well as morphological data from the male gonopod, to gain insights into phylogenetic relationships among individuals collected in the northeastern United States, where this taxon is considered to be invasive, and from Kansas. Our data reveal evidence for three cryptic species in our collections, in addition to O.virilis sensu stricto; all four clades are separated by both mitochondrial and nuclear sequence data. In addition, two of the newly discovered species, O.sp. nov. A and O.sp. nov. B, are distinguishable from O.virilis by significant differences in gonopod morphology (no data on gonopod morphology were available for O.sp. nov. C). O.sp. nov. A was collected at numerous sites in Massachusetts; additional sampling is required to determine if this species is native to New England. Two other taxa, O.sp. nov. B and O.sp. nov. C, were both collected from sites in eastern Kansas, and historically have probably been considered to be O.nais. In summary, this investigation indicates that this species complex may harbor a great deal of unknown biodiversity over the rest of its described range, and suggests that further attention to the phylogenetics and phylogeography of North American crayfishes may yield interesting insights into the evolution of biodiversity. PMID:18346914

Mathews, Lauren M; Adams, Luke; Anderson, Erica; Basile, Matthew; Gottardi, Elizabeth; Buckholt, Michael A

2008-07-01

71

Critical review of actually available chemical compounds for prevention and management of cyanobacterial blooms.  

PubMed

Cyanobacteria proliferation is among the most threatening consequences of freshwater pollution. Health risks from human and other-organism exposure to cyanobacteria have led to an effort to find practical methods for cyanobacterial water-bloom reduction. Hence, methods and techniques have been developed in order to reduce the amount of phosphorus or to decrease the abundance of nuisance phytoplankton species directly in the water bodies (in-lake measures). Although these "acute" methods do not solve the problem of catchment area eutrophication, they are cheaper, easier to manage, and for some areas they are the only way to protect human and environmental health against massive cyanobacterial proliferation. This review summarizes the extent of knowledge and published data about the management using metals (Al, Fe, Cu, Ag, Ca), photosensitizers (hydrogen peroxide, phthalocyanines, TiO(2)), herbicides and chemicals derived from natural compounds as fast and efficient removal agents of cyanobacteria. This review concludes that some compounds, when non-persistent and ecotoxicologically acceptable may help to manage cyanobacterial blooms in an efficient way compared to previous methods (e.g. copper sulfate). PMID:21925702

Jan?ula, Daniel; Maršálek, Blahoslav

2011-11-01

72

Comparison of two freshwater turtle species as monitors of environmental contamination  

SciTech Connect

Two species of turtles that occupy different ecological niches were compared for their usefulness as monitors of contamination in freshwater ecosystems. Trachemys scripta (Agassiz) and Chelydra serpentina (Linnaeus) were selected for comparison based on species abundance and differences in food habits and sediment contact. A review of the literature on contaminants in turtles and results of preliminary surveys conducted at the field sites, which are included in this study, were used to direct and focus this research project. White Oak Lake, a settling basin for low-level radioactive and nonradioactive contaminants, and Bearden Creek Embayment, an uncontaminated reference site upriver, were used as study sites in the investigation of turtles as indicators of chemical contamination. Turtles were analyzed for concentrations of strontium-90, cesium-137, cobalt 60, and mercury in specific target tissues, and for single-stranded DNA breaks, a non-specific indicator of possible exposure to genotoxic agents in the environment. 133 refs., 2 figs., 15 tabs.

Meyers-Schoene, L. (IT Corp., Knoxville, TN (USA)); Walton, B.T. (Oak Ridge National Lab., TN (USA))

1990-04-01

73

Diversity and Distribution of Freshwater Amphipod Species in Switzerland (Crustacea: Amphipoda)  

PubMed Central

Amphipods are key organisms in many freshwater systems and contribute substantially to the diversity and functioning of macroinvertebrate communities. Furthermore, they are commonly used as bioindicators and for ecotoxicological tests. For many areas, however, diversity and distribution of amphipods is inadequately known, which limits their use in ecological and ecotoxicological studies and handicaps conservation initiatives. We studied the diversity and distribution of amphipods in Switzerland (Central Europe), covering four major drainage basins, an altitudinal gradient of>2,500 m, and various habitats (rivers, streams, lakes and groundwater). We provide the first provisional checklist and detailed information on the distribution and diversity of all amphipod species from Switzerland. In total, we found 29 amphipod species. This includes 16 native and 13 non-native species, one of the latter (Orchestia cavimana) reported here for the first time for Switzerland. The diversity is compared to neighboring countries. We specifically discuss species of the genus Niphargus, which are often receiving less attention. We also found evidence of an even higher level of hidden diversity, and the potential occurrence of further cryptic species. This diversity reflects the biogeographic past of Switzerland, and suggests that amphipods are ideally suited to address questions on endemism and adaptive radiations, post-glaciation re-colonization and invasion dynamics as well as biodiversity-ecosystem functioning relationships in aquatic systems. PMID:25354099

Altermatt, Florian; Alther, Roman; Fišer, Cene; Jokela, Jukka; Konec, Marjeta; Küry, Daniel; Mächler, Elvira; Stucki, Pascal; Westram, Anja Marie

2014-01-01

74

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.

2005-05-01

75

First report of saxitoxin production by a species of the freshwater benthic cyanobacterium, Scytonema Agardh.  

PubMed

Saxitoxins or paralytic shellfish poisons (PSP) are neurotoxins produced by some species of freshwater cyanobacteria and marine dinoflagellates. Samples collected from the metaphyton of a drinking-water supply's pre-treatment reservoir and a small eutrophic lake in New Zealand returned positive results when screened using a Jellett PSP Rapid Test Kit. The dominant species in the sample was identified as Scytonema cf. crispum. A non-axenic clonal culture (UCFS10) was isolated from the lake. The partial 16S rRNA gene sequence shared only a 91% or less sequence similarity with other Scytonema species, indicating that it is unlikely that this genus is monophyletic and that further in-depth phylogenetic re-evaluation is required. The sxtA gene, which is known to be involved in saxitoxin production, was detected in UCFS10. Saxitoxin concentrations were determined from the lake samples and from UCFS10 using pre-column oxidation high performance liquid chromatography with fluorescence detection. Saxitoxin was the only variant detected and this was found at concentrations of 65.6 ?g g?¹ dry weight in the lake sample and 119.4 ?g g?¹ dry weight or 1.3 pg cell?¹ in UCFS10. This is the first confirmation of a saxitoxin-producing species in New Zealand and the first report of saxitoxin production by a species of Scytonema. PMID:21223973

Smith, Francine M J; Wood, Susanna A; van Ginkel, Roel; Broady, Paul A; Gaw, Sally

2011-03-15

76

How do dams affect freshwater fish distributions in Japan? Statistical analysis of native and nonnative species with various life histories  

Microsoft Academic Search

We examined the effects of dams on freshwater fish species based on data collected during 1990–2004 from 200 drainage systems\\u000a in Japan. Of the 76 fish species examined, the occurrence of 20 species within Petromyzontidae, Cyprinidae, Cobitididae, Salmonidae,\\u000a Cottidae, and Gobiidae was negatively affected by the presence of dams located in the downstream reaches of fish survey sites,\\u000a whereas the

Mideok Han; Michio Fukushima; Satoshi Kameyama; Takehiko Fukushima; Bunkei Matsushita

2008-01-01

77

Freshwater diatoms as environmental indicators: evaluating the effects of eutrophication using species morphology and biological indices.  

PubMed

Anthropogenic eutrophication is a major form of perturbation in freshwaters, and several approaches aim to recognise its effects on lake ecosystems. We compared the responses of diatom species morphology, diversity indices and diatom indices to total phosphorus, total nitrogen and distance from a point stressor causing eutrophication in a large lake. We specifically examined the degree to which extent nutrients and distance to the stressor affect variation in the values of various biological indices and diatom valve size. In addition, special attention was given to the adequate repetition of diatom valve width measurements in the context of environmental assessment. Our results showed that diatom valve width was a better indicator of nutrient concentrations than any of the diatom and diversity indices examined. However, the results varied between the two study transects, suggesting that the diatom-based variables not only respond to nutrients but also to other environmental factors (e.g. shoreline morphology). We also found that when using the method based on diatom morphology, one should measure more valves than has been originally suggested to provide a more reliable picture of response to eutrophication. We argue that diatom morphology could be considered as an additional environmental assessment tool, because it may complement the information provided by the traditional diatom indices. Diatom valve width may also be more sensitive to early phases of the eutrophication process and its effects on freshwater ecosystems than various diatom indices that were developed in regional contexts with wide ranges in nutrient levels. PMID:25864081

Vilmi, Annika; Karjalainen, Satu Maaria; Landeiro, Victor L; Heino, Jani

2015-05-01

78

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

2008-01-01

79

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. PMID:15347510

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

2004-01-01

80

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.

2005-01-01

81

Assessing Species Boundaries Using Multilocus Species Delimitation in a Morphologically Conserved Group of Neotropical Freshwater Fishes, the Poecilia sphenops Species Complex (Poeciliidae)  

PubMed Central

Accurately delimiting species is fundamentally important for understanding species diversity and distributions and devising effective strategies to conserve biodiversity. However, species delimitation is problematic in many taxa, including ‘non-adaptive radiations’ containing morphologically cryptic lineages. Fortunately, coalescent-based species delimitation methods hold promise for objectively estimating species limits in such radiations, using multilocus genetic data. Using coalescent-based approaches, we delimit species and infer evolutionary relationships in a morphologically conserved group of Central American freshwater fishes, the Poecilia sphenops species complex. Phylogenetic analyses of multiple genetic markers (sequences of two mitochondrial DNA genes and five nuclear loci) from 10/15 species and genetic lineages recognized in the group support the P. sphenops species complex as monophyletic with respect to outgroups, with eight mitochondrial ‘major-lineages’ diverged by ?2% pairwise genetic distances. From general mixed Yule-coalescent models, we discovered (conservatively) 10 species within our concatenated mitochondrial DNA dataset, 9 of which were strongly supported by subsequent multilocus Bayesian species delimitation and species tree analyses. Results suggested species-level diversity is underestimated or overestimated by at least ~15% in different lineages in the complex. Nonparametric statistics and coalescent simulations indicate genealogical discordance among our gene tree results has mainly derived from interspecific hybridization in the nuclear genome. However, mitochondrial DNA show little evidence for introgression, and our species delimitation results appear robust to effects of this process. Overall, our findings support the utility of combining multiple lines of genetic evidence and broad phylogeographical sampling to discover and validate species using coalescent-based methods. Our study also highlights the importance of testing for hybridization versus incomplete lineage sorting, which aids inference of not only species limits but also evolutionary processes influencing genetic diversity. PMID:25849959

Bagley, Justin C.; Alda, Fernando; Breitman, M. Florencia; Bermingham, Eldredge; van den Berghe, Eric P.; Johnson, Jerald B.

2015-01-01

82

Molecular Evidence for High Frequency of Multiple Paternity in a Freshwater Shrimp Species Caridina ensifera  

PubMed Central

Background Molecular genetic analyses of parentage provide insights into mating systems. Although there are 22,000 members in Malacostraca, not much has been known about mating systems in Malacostraca. The freshwater shrimp Caridina ensifera blue, is a new species belonging to Malacostraca which was discovered recently in Sulawesi, Indonesia. Due to its small body size and low fecundity, this species is an ideal species to study the occurrence and frequency of multiple paternity and to understand of how the low fecundity species persist and evolve. Methodology/Principal Findings In this study, we developed four polymorphic microsatellites from C. ensifera and applied them to investigate the occurrence and frequency of multiple paternity in 20 C. ensifera broods caught from Lake Matano, Sulawesi. By genotyping the mother and all offspring from each brood we discovered multiple paternity in all 20 broods. In most of the 20 broods, fathers contributed skewed numbers of offspring and there was an apparent inverse correlation between reproductive success of sires and their relatedness to mothers. Conclusions/Significance Our results in combination with recent reports on multiple paternity in crayfish, crab and lobster species suggests that multiple paternity is common in Malacostraca. Skewed contribution of fathers to the numbers of offspring and inverse correlation between reproductive success of sires and their relatedness to mothers suggest that sperm competition occurred and/or pre- and postcopulatory female choice happen, which may be important for avoiding the occurrence of inbreeding and optimize genetic variation in offspring and for persistence and evolution of low fecundity species. PMID:20856862

Yue, Gen Hua; Chang, Alex

2010-01-01

83

Ontogeny of critical and prolonged swimming performance for the larvae of six Australian freshwater fish species.  

PubMed

Critical (<30?min) and prolonged (>60?min) swimming speeds in laboratory chambers were determined for larvae of six species of Australian freshwater fishes: trout cod Maccullochella macquariensis, Murray cod Maccullochella peelii, golden perch Macquaria ambigua, silver perch Bidyanus bidyanus, carp gudgeon Hypseleotris spp. and Murray River rainbowfish Melanotaenia fluviatilis. Developmental stage (preflexion, flexion, postflexion and metalarva) better explained swimming ability than did length, size or age (days after hatch). Critical speed increased with larval development, and metalarvae were the fastest swimmers for all species. Maccullochella macquariensis larvae had the highest critical [maximum absolute 46.4?cm?s(-1) and 44.6 relative body lengths (L(B)) s(-1)] and prolonged (maximum 15.4?cm?s(-1), 15.6 L(B) s(-1)) swimming speeds and B. bidyanus larvae the lowest critical (minimum 0.1?cm?s(-1), 0.3 L(B) s(-1)) and prolonged swimming speeds (minimum 1.1?cm?s(-1), 1.0 L(B) s(-1)). Prolonged swimming trials determined that the larvae of some species could not swim for 60?min at any speed, whereas the larvae of the best swimming species, M. macquariensis, could swim for 60?min at 44% of the critical speed. The swimming performance of species with precocial life-history strategies, with well-developed larvae at hatch, was comparatively better and potentially had greater ability to influence their dispersal by actively swimming than species with altricial life-history strategies, with poorly developed larvae at hatch. PMID:24814314

Kopf, S M; Humphries, P; Watts, R J

2014-06-01

84

Hidden Biodiversity in an Ecologically Important Freshwater Amphipod: Differences in Genetic Structure between Two Cryptic Species  

PubMed Central

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

2013-01-01

85

DNA barcoding common non-native freshwater fish species in Turkey: low genetic diversity but high population structuring.  

PubMed

Negative impacts of introduced non-native freshwater species on native species have been increasingly recognized in the world as well as in Turkey. However, there has been relatively little attention on genetic characterization of alien freshwater fishes in their non-native distribution range and virtually no study has been conducted in Turkey despite its crucial importance in invasion biology. The purpose of this study was to elucidate genetic diversity of common non-native freshwater fish species (Carassius auratus, Carassius gibelio, Gambusia holbrooki, Lepomis gibbosus, and Pseudorasbora parva) using mitochondrial Cytochrome c oxidase subunit I (COI) sequences; known as DNA barcodes. Through the whole dataset, seventeen haplotypes (haplotype diversity = 0.8908) were found containing 145 COI sequences. Mean Kimura two-parameter genetic distances were calculated as 0.209 for interspecific distance and 0.009 for intraspecific variation. COI barcode diversity among populations of the same species was found to be low, especially for C. gibelio, G. holbrooki, and L. gibbosus populations which were 0.5%, 0.6%, and 0.3%, respectively. Our results clearly demonstrate the effectiveness of the DNA barcoding approach both for identifications at species level and revealing intraspecific variation among populations, which could be used for effective management measures for invasive species and conservation strategies for indigenous and endemic species. PMID:23298166

Keskin, Emre; A?damar, Sevan; Tarkan, Ali Serhan

2013-06-01

86

The occurrence of an Australian leech species (genus Helobdella) in German freshwater habitats as revealed by mitochondrial DNA sequences.  

PubMed

The freshwater leech Helobdella europaea Kutschera 1987 was discovered twenty years ago in Germany and described as a new species. Here, we show that this leech is genetically identical with the Australian species Helobdella papillornata (CO-I-mt-DNA sequence identity of alignment positions: 98%). We conclude that H. europaea (syn. H. papillornata) represents an introduced annelid that occupies the same ecological niche as the common European leech H. stagnalis L. PMID:15324849

Pfeiffer, I; Brenig, B; Kutschera, U

2004-10-01

87

Biochemical composition of three algal species proposed as food for captive freshwater mussels  

USGS Publications Warehouse

To identify potential diets for rearing captive freshwater mussels, the protein, carbohydrate (CHO), and lipid contents of two green algae, Neochloris oleoabundans, Bracteacoccus grandis, and one diatom, Phaeodactylum tricornutum, were compared at different growth stages. The fatty acid and sterol composition were also identified. Protein was greatest (55-70%) for all species at late log growth stage (LL), and declined in late stationary (LS) growth. CHO was greatest at LS stage for all species (33.9-56.4% dry wt). No significant change in lipid levels occurred with growth stage, but tended to increase in N. oleoabundans. Mean lipid content differed significantly in the order: N. oleoabundans > P. tricornutum > B. grandis. Total fatty acids (TFA) were higher at LS stage compared to other stages in the two green algae, and stationary stage in the diatom. Mean unsaturated fatty acids (UFA) as %TFA was significantly higher in N. oleoabundans than the other species. The green algae contained high percentages of C-18 polyunsaturated fatty acids (PUFAs), while the diatom was abundant in C-16 saturated and mono-unsaturated fatty acids and C-20 PUFA fatty acids. Growth stage had no effect on sterol concentration of any species. B. grandis showed significantly higher sterol levels than the other species except P. tricornutum at S stage. B. grandis was characterized by predominantly ??5, C-29 sterols, while N. oleoabundans synthesized ??5,7, ??5,7,22, and ??7, C-28 sterols. P. tricornutum produced primarily a ??5,22, C-28 sterol, and a small amount of a ??7,22, C-28 sterol.

Gatenby, C.M.; Orcutt, D.M.; Kreeger, D.A.; Parker, B.C.; Jones, V.A.; Neves, R.J.

2003-01-01

88

Description of seven candidate species affiliated with the phylum Actinobacteria, representing planktonic freshwater bacteria  

Microsoft Academic Search

Actinobacteria comprise a substantial fraction of the bacterioplankton in freshwater lakes and streams. Numerous cultivation-independent investigations have retrieved actinobacterial 16S rRNA gene sequences from such habitats. The taxa detected in freshwater habitats are usually absent from terrestrial and marine systems. So far, none of the indigenous freshwater lineages is represented by a taxon with a validly published name. The seven

Martin W. Hahn; A. F. Yassin

2009-01-01

89

Day and night trophic variations of dominant fish species in a lagoon influenced by freshwater seeps.  

PubMed

The aim of this study was to determine the trophic structure and nycthemeral variations in the diet of dominant fish species (Ariopsis felis, Bairdiella chrysoura, Micropogonias undulatus, Eucinostomus gula, Eucinostomus argenteus, Lagodon rhomboides and Sphoeroides testudineus) in Celestun Lagoon, a biosphere reserve located in the southern Gulf of Mexico, and influenced by freshwater seeps. A total of 1473 stomachs were analysed and nine trophic groups were recorded. Bray-Curtis analyses with analyses of similarity (ANOSIM) statistical tests were used to determine two groups of feeding guilds: zoobenthivores and omnivores, with significant differences between time and habitat. The relationships between fish feeding habits, size class and environmental variables were investigated using canonical correspondence analysis (CCA). Most of the species showed a low niche breadth with high specialization towards amphipod consumption, with the exception of L. rhomboides (0·60), which indicated generalist feeding. This study in a protected area is an important source of information for drawing up conservation policies in relation to the management of aquatic resources, and will aid in the establishment of priority areas for conservation. PMID:23331138

Arceo-Carranza, D; Vega-Cendejas, M E; Hernández de Santillana, M

2013-01-01

90

Acute Toxicity and Bioaccumulation of Chloroform to Four Species of Freshwater Fish  

SciTech Connect

Acute toxicity of chloroform to four species of freshwater fish was studied in flow-through 96-hr toxicity tests. Chloroform is toxic to fish in the tens of parts per million, a concentration well above that which would be expected to be produced under normal power plant chlorination conditions. Investigations of acute toxicity of chloroform and the bioaccumulation of chlorinated compounds in tissues of fish revealed differences in tolerance levels and tissue accumulations. Mean 96-hr LC{sub 50}s for chloroform were 18 ppm for rainbow trout and bluegill, 51 ppm for largemouth bass and 75 ppm for channel catfish. Mortalities of bluegill and largemouth bass occurred during the first 4 hr of exposure while rainbow trout and channel catfish showed initial tolerance and mortalities occurred during the latter half of the 96-hr exposure. Rainbow trout had the highest level of chloroform tissue accumulation, 7 {micro}g/g tissue, catfish the second highest, 4 {micro}g/g tissue, followed by bluegill and largemouth bass which each accumulated about 3 {micro}g/g tissue. Accumulation of chloroform was less than one order of magnitude above water concentrations for all species.

,

1980-08-01

91

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

PubMed

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 found on the gills of the freshwater cobbler Tandanus bostocki Whitely and western minnow Galaxias occidentalis Ogilby in two different river systems. PMID:19731098

Hassan, Marina; Jones, Brian; Lymbery, Alan J

2009-10-01

92

Nematode species at risk--a metric to assess pollution in soft sediments of freshwaters.  

PubMed

Soft sediments are often highly polluted as many of the toxic chemicals introduced into surface waters bind to settling particles. The resulting accumulation of pollutants in the sediments poses a risk for benthic communities. However, pollution induced changes in benthic communities have been difficult to determine when using macro-invertebrates as bioindicators, as these organisms are often absent in soft sediment. The present study therefore examined the ability of meiofaunal organisms, specifically, nematodes, to assess the ecological status of soft sediments. Over a 9-year period, nematode communities present in sediments collected from large rivers and lake Constance in Germany were studied. These sediments showed a large range of physico-chemical properties and anthropogenic contamination. After the degree of metal and organic contamination was translated into ecotoxicologically more relevant toxic units (TUs), multivariate methods were used to classify nematode taxa in species at risk (NemaSPEAR) or not at risk (NemaSPE(not)AR). This approach clearly distinguished the influence of sediment texture from that of the toxic potential of the samples and thus allowed classification of the nematode species according to their sensitivity to or tolerance of toxic stress. Two indices, expressing the proportion of species at risk within a sample (NemaSPEAR[%](metal), NemaSPEAR[%](organic)), were calculated from independent data sets obtained in field and experimental studies and showed good correlations with the toxic potential (field data) or chemical concentrations (microcosm data). NemaSPEAR[%] indices for metal and organic pollution were therefore judged to be suitable for assessing the impact of chemical contamination of freshwater soft sediments. PMID:21482435

Höss, S; Claus, E; Von der Ohe, P C; Brinke, M; Güde, H; Heininger, P; Traunspurger, W

2011-07-01

93

Two new species of Rhabdochona (Nematoda: Rhabdochonidae) from freshwater fishes in Thailand.  

PubMed

Two new species ofrhabdochonid nematodes are described from the intestine of freshwater fishes in Chiang Mai Province, northern Thailand: Rhabdochona (Rhabdochona) pseudomysti sp. n. from the catfish Pseudomystus siamensis (Regan) (Bagridae, Siluriformes) in the Fang Brook, a tributary of the Kok River (the Mekong River basin), Fang District and Rhabdochona (Globochona) thaiensis sp. n. from the cyprinid Mystacoleucus marginatus (Valenciennes) (Cyprinidae, Cypriniformes) in the Ping River (the Chao Phraya River basin), Muang District. Rhabdochona pseudomysti is mainly characterized by simple, leaf-like oval deirids (a unique feature among Rhabdochona spp.), a prostom with 14 anterior teeth, the presence of basal prostomal teeth, the length ratio of the muscular and glandular portions of oesophagus (1:2.1-2.6), an unusually long left spicule (1.10-1.22 mm), length ratio of spicules (1:11.5-14.7), arrangement of genital papillae, and conspicuously elevated vulval lips. Rhabdochona thaiensis differs from other representatives of the subgenus Globochona Moravec, 1972 possessing caudal projections on the tail tip in that it has only 2 claw-shaped projections located ventrally on the tail tip of both males and females; the species is mainly characterized by the presence of distinct pseudolabia, 8 anterior prostomal teeth, absence of basal teeth, bifurcated deirids, length ratio of the muscular and glandular portions of oesophagus (1:11.3-11.9), conspicuously short (135-141 microm) left spicule, arrangement of genital papillae, and somewhat elevated vulval lips. Fully developed eggs of R. pseudomysti and R. thaiensis remain unknown. These are the first nominal species of Rhabdochona reported from Thailand. PMID:22053618

Moravec, Frantisek; Yooyen, Thanapon

2011-09-01

94

Comparison of Two Freshwater Turtle Species as Monitors of Environmental Contamination  

SciTech Connect

Two species of turtles that occupy different ecological niches were compared for their usefulness as monitors of contamination in freshwater ecosystems. Trachemvs scrinta (Agassiz) (yellow-bellied slider) and Chelvdra sernentina (Linnaeus) (common snapping turtle) were selected for comparison based on species abundance and differences in food habits and sediment contact. A review of the literature on contaminants in turtles and results of preliminary surveys conducted at the field sites, which are included in this study, were used to direct and focus this research project. White Oak Lake, a settling basin for low-level radioactive and nonradioactive contaminants, and Bearden Creek Embayment, an uncontaminated reference site upriver, were used as study sites in the investigation of turtles as indicators of chemical contamination. Turtles were analyzed for concentrations of strontium-go, cesium-137, cobalt 60, and mercury in specific target tissues, and for single-stranded DNA breaks, a non-specific indicator of possible exposure to genotoxic agents in the environment. Significantly higher concentrations of {sup 90}Sr, {sup 137}Cs, {sup 60}Co, and mercury were detected in turtles from White Oak Lake than in turtles from the reference site. In addition, turtles from White Oak Lake contained a significantly greater amount of DNA damage than those from the reference site. Although this suggests greater exposure of White Oak Lake turtles to genotoxic agents, further studies are needed to establish the cause of the enhanced amount of single-stranded breaks. Interspecific comparisons of the turtles from White Oak Lake indicated that diet may play a significant role in the exposure of turtles to certain contaminants. No difference was detected between the concentrations of {sup 90}Sr, {sup 137}Cs, {sup 60}Co between the two species.

Meyers-Schone, L.

1990-01-01

95

Complementary nontargeted and targeted mass spectrometry techniques to determine bioaccumulation of halogenated contaminants in freshwater species.  

PubMed

Assessing the toxicological significance of complex environmental mixtures is challenging due to the large number of unidentified contaminants. Nontargeted analytical techniques may serve to identify bioaccumulative contaminants within complex contaminant mixtures without the use of analytical standards. This study exposed three freshwater organisms (Lumbriculus variegatus, Hexagenia spp., and Pimephales promelas) to a highly contaminated soil collected from a recycling plant fire site. Biota extracts were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and mass defect filtering to identify bioaccumulative halogenated contaminants. Specific bioaccumulative isomers were identified by comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry (GCxGC-HRToF). Targeted analysis of mixed brominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PXDD/PXDFs, X = Br and Cl) was performed by atmospheric pressure gas chromatography tandem mass spectrometry (APGC-MS/MS). Relative sediment and biota instrument responses were used to estimate biota-sediment accumulation factors (BSAFs). Bioaccumulating contaminants varied among species and included polychlorinated naphthalenes (PCNs), polychlorinated dibenzofurans (PCDFs), chlorinated and mixed brominated/chlorinated anthracenes/phenanthrenes, and pyrenes/fluoranthenes (Cl-PAHs and X-PAHs, X = Br and Cl), as well as PXDD/PXDFs. Bioaccumulation potential among isomers also varied. This study demonstrates how complementary high-resolution mass spectrometry techniques identify persistent and bioaccumulative contaminants (and specific isomers) of environmental concern. PMID:25365627

Myers, Anne L; Watson-Leung, Trudy; Jobst, Karl J; Shen, Li; Besevic, Sladjana; Organtini, Kari; Dorman, Frank L; Mabury, Scott A; Reiner, Eric J

2014-12-01

96

Feeding kinematics of freshwater turtles: what advantage do invasive species possess?  

PubMed

The red-eared slider (Trachemys scripta) is an invasive turtle species that is displacing the populations of native freshwater turtles in many countries. However, the mechanism that makes red-eared sliders superior competitors has been less well studied. In this study, we compare the feeding kinematics of the red-eared slider with those of Reeves' pond turtle (Mauremys reevesii), a turtle native to East Asia, and offer an explanation as to why red-eared sliders are superior in food competition. Reeves' pond turtles sympatric to red-eared sliders have been reported to have a mainly durophagous diet in contrast to the preference for a soft diet in areas of allopatry to red-eared sliders, indicating the dietary shift resulted from food competition. Maximum neck extension and retraction speed are considered to be indicators of striking ability, but were not found to be superior in red-eared sliders. In fact, maximum neck extension speed was significantly higher in Reeves' pond turtles, though this advantage may be counteracted by the longer neck of Reeves' pond turtles, resulting in similar neck extension times. On the other hand, red-eared sliders had a significantly shorter gape cycle time and neck retraction time, indicating that they can complete feeding in a short time. Therefore, red-eared sliders are suggested to be superior in food competition not due to their striking ability, but due to exploiting preferable food in a shorter time. PMID:25156933

Nishizawa, Hideaki; Tabata, Runa; Hori, Tomoya; Mitamura, Hiromich; Arai, Nobuaki

2014-10-01

97

Where Are All the Fish: Potential of Biogeographical Maps to Project Current and Future Distribution Patterns of Freshwater Species  

PubMed Central

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

2012-01-01

98

Fungal Parasitism: Life Cycle, Dynamics and Impact on Cyanobacterial Blooms  

PubMed Central

Many species of phytoplankton are susceptible to parasitism by fungi from the phylum Chytridiomycota (i.e. chytrids). However, few studies have reported the effects of fungal parasites on filamentous cyanobacterial blooms. To investigate the missing components of bloom ecosystems, we examined an entire field bloom of the cyanobacterium Anabaena macrospora for evidence of chytrid infection in a productive freshwater lake, using a high resolution sampling strategy. A. macrospora was infected by two species of the genus Rhizosiphon which have similar life cycles but differed in their infective regimes depending on the cellular niches offered by their host. R. crassum infected both vegetative cells and akinetes while R. akinetum infected only akinetes. A tentative reconstruction of the developmental stages suggested that the life cycle of R. crassum was completed in about 3 days. The infection affected 6% of total cells (and 4% of akinètes), spread over a maximum of 17% of the filaments of cyanobacteria, in which 60% of the cells could be parasitized. Furthermore, chytrids may reduce the length of filaments of Anabaena macrospora significantly by “mechanistic fragmentation” following infection. All these results suggest that chytrid parasitism is one of the driving factors involved in the decline of a cyanobacteria blooms, by direct mortality of parasitized cells and indirectly by the mechanistic fragmentation, which could weaken the resistance of A. macrospora to grazing. PMID:23593345

Gerphagnon, Mélanie; Latour, Delphine; Colombet, Jonathan; Sime-Ngando, Télesphore

2013-01-01

99

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

100

Differential tolerance to cyanobacterial exposure between geographically distinct populations of Perca fluviatilis.  

PubMed

Toxic cyanobacterial blooms are an important problem worldwide. Cyanobacteria may negatively impact young-of-the-year (YOY) fish directly (toxin production, turbidity, decrease in water quality) or indirectly (trophic toxin transfer, changes in prey species composition). Here we test whether there are any differences in cyanobacterial tolerance between four geographically distinct populations of European perch (Perca fluviatilis). We show that P. fluviatilis may develop tolerance against cyanobacteria demonstrated by the ability of individuals from a marine site (exposed to annual cyanobacterial blooms) to increase their detoxification more than individuals from an oligotrophic site (rarely exposed to cyanobacteria). Our results also revealed significant interaction effects between genotypes within a population and response to cyanobacterial exposure in terms of absolute growth and detoxification activity. This genotype by treatment interaction may result in local adaptations to cyanobacterial exposure in P. fluviatilis. Hence, the sensitivity against cyanobacterial exposure may differ between within species populations increasing the importance of local management of fish populations. PMID:24018361

Persson, Karl-Johan; Bergström, Kristofer; Mazur-Marzec, Hannah; Legrand, Catherine

2013-12-15

101

Characterization of the salt stress vulnerability of three invasive freshwater plant species using a metabolic profiling approach.  

PubMed

The effects of salt stress on freshwater plants has been little studied up to now, despite the fact that they are expected to present different levels of salt sensitivity or salt resistance depending on the species. The aim of this work was to assess the effect of NaCl at two concentrations on three invasive freshwater species, Elodea canadensis, Myriophyllum aquaticum and Ludwigia grandiflora, by examining morphological and physiological parameters and using metabolic profiling. The growth rate (biomass and stem length) was reduced for all species, whatever the salt treatment, but the response to salt differed between the three species, depending on the NaCl concentration. For E. canadensis, the physiological traits and metabolic profiles were only slightly modified in response to salt, whereas M. aquaticum and L. grandiflora showed great changes. In both of these species, root number, photosynthetic pigment content, amino acids and carbohydrate metabolism were affected by the salt treatments. Moreover, we are the first to report the salt-induced accumulation of compatible solutes in both species. Indeed, in response to NaCl, L. grandiflora mainly accumulated sucrose. The response of M. aquaticum was more complex, because it accumulated not only sucrose and myo-inositol whatever the level of salt stress, but also amino acids such as proline and GABA, but only at high NaCl concentrations. These responses are the metabolic responses typically found in terrestrial plants. PMID:25544588

Thouvenot, Lise; Deleu, Carole; Berardocco, Solenne; Haury, Jacques; Thiébaut, Gabrielle

2015-03-01

102

Life history and biogeographic diversification of an endemic western North American freshwater fish clade using a comparative species tree approach.  

PubMed

The west coast of North America contains a number of biogeographic freshwater provinces which reflect an ever-changing aquatic landscape. Clues to understanding this complex structure are often encapsulated genetically in the ichthyofauna, though frequently as unresolved evolutionary relationships and putative cryptic species. Advances in molecular phylogenetics through species tree analyses now allow for improved exploration of these relationships. Using a comprehensive approach, we analyzed two mitochondrial and nine nuclear loci for a group of endemic freshwater fish (sculpin-Cottus) known for a wide ranging distribution and complex species structure in this region. Species delimitation techniques identified three novel cryptic lineages, all well supported by phylogenetic analyses. Comparative phylogenetic analyses consistently found five distinct clades reflecting a number of unique biogeographic provinces. Some internal node relationships varied by species tree reconstruction method, and were associated with either Bayesian or maximum likelihood statistical approaches or between mitochondrial, nuclear, and combined datasets. Limited cases of mitochondrial capture were also evident, suggestive of putative ancestral hybridization between species. Biogeographic diversification was associated with four major regions and revealed historical faunal exchanges across regions. Mapping of an important life-history character (amphidromy) revealed two separate instances of trait evolution, a transition that has occurred repeatedly in Cottus. This study demonstrates the power of current phylogenetic methods, the need for a comprehensive phylogenetic approach, and the potential for sculpin to serve as an indicator of biogeographic history for native ichthyofauna in the region. PMID:22982759

Baumsteiger, Jason; Kinziger, Andrew P; Aguilar, Andres

2012-12-01

103

Comparative study of the lipids of four dominating species of freshwater plants and algae of the Shulgan river.  

PubMed

The fatty acid and lipid compositions of four dominating species of plants and algae of the Shulgan river--Alliaria petiolata, Rhynchostegium riparioides, Sphaeroplea annulina, and Rhizoclonium hieroglyphicum--were studied. The composition of phospho-, glyco-, and neutral lipids was investigated. A betaine lipid 1(3), 2-diacylglyceryl-(3)-O-4-(N,N,N-trimethyl)homoserine was detected in the polar lipid fraction of the Rhynchostegium riparioides bryophyte. Characteristic distribution of lipids and fatty acids of freshwater plants and algae is discussed in term of various species specificity. PMID:10611535

Rozentsvet, O A; Kozlov, V G; Dembitsky, V M

1999-11-01

104

Variation in cyanobacterial hepatotoxin (microcystin) content of water samples and two species of fishes collected from a shallow lake in Algeria.  

PubMed

Microcystins (MCs) produced from cyanobacteria can accumulate in freshwater fish tissues. In this study, variations in these toxins content were examined monthly in water samples and two species of fish in Lake Oubeira, Algeria, from April 2010 to March 2011. During the study period, MCs were analyzed using protein phosphatase type 2A (PP2A) inhibition assay. In lake water, total (dissolved and intracellular toxins) MC concentrations by PP2A ranged from 0.028 to 13.4 ?g equivalent MC-LR/l, with a peak in September 2010. MC-LR was the dominant variant (90 % of the total) in water samples, followed by MC-YR and MC-(H4)YR. The highest MC concentration in the omnivorous common carp (Cyprinus carpio) was found in the order intestine > hepatopancreas > muscle; however, in the carnivorous European eel (Anguilla anguilla) the order was liver > intestine > muscle. Highest MC concentrations in the intestine tissue of the common carp were found between August and November 2010 where high MC concentrations were detected in water samples, whereas high levels of MCs in the liver of the European eel were found later between January and February 2011. During the entire period of study, the World Health Organization (WHO) lifetime limit for tolerable daily intake was exceeded only in common carp muscle. PMID:24445842

Amrani, Amina; Nasri, Hichem; Azzouz, Amina; Kadi, Yacine; Bouaïcha, Noureddine

2014-04-01

105

Metagenomic Study of Iron Homeostasis in Iron Depositing Hot Spring Cyanobacterial Community  

NASA Technical Reports Server (NTRS)

Introduction: It is not clear how an iron-rich thermal hydrosphere could be hospitable to cyanobacteria, since reduced iron appears to stimulate oxidative stress in all domains of life and particularly in oxygenic phototrophs. Therefore, metagenomic study of cyanobacterial community in iron-depositing hot springs may help elucidate how oxygenic prokaryotes can withstand the extremely high concentrations of reactive oxygen species (ROS) produced by interaction between environmental Fe2+ and O2. Method: Anchor proteins from various species of cyanobacteria and some anoxygenic phototrophs were selected on the basis of their hypothetical role in Fe homeostasis and the suppression of oxidative stress and were BLASTed against the metagenomes of iron-depositing Chocolate Pots and freshwater Mushroom hot springs. Results: BLASTing proteins hypothesized to be involved in Fe homeostasis against the microbiomes from the two springs revealed that iron-depositing hot spring has a greater abundance of defensive proteins such as bacterioferritin comigratory protein (Bcp) and DNA-binding Ferritin like protein (Dps) than a fresh-water hot spring. One may speculate that the abundance of Bcp and Dps in an iron-depositing hot spring is connected to the need to suppress oxidative stress in bacteria inhabiting environments with high Fe2+ concnetration. In both springs, Bcp and Dps are concentrated within the cyanobacterial fractions of the microbial community (regardless of abundance). Fe3+ siderophore transport (from the transport system permease protein query) may be less essential to the microbial community of CP because of the high [Fe]. Conclusion: Further research is needed to confirm that these proteins are unique to photoautotrophs such as those living in iron-depositing hot spring.

Brown, I.; Franklin H.; Tringe, S. G.; Klatt, C. G.; Bryant, D. A.; Sarkisova, S. A.; Guevara, M.

2010-01-01

106

Selenium:Mercury Molar Ratios in Freshwater Fish from Tennessee: Individual, Species, and Geographical Variations have Implications for Management  

PubMed Central

Vertebrates, including humans, can experience adverse effects from mercury consumed in fish. Humans often prefer large predatory fish that bioaccumulate high mercury levels. Recent attention has focused on the role of selenium countering mercury toxicity, but there is little research on the selenium:mercury molar ratios in freshwater fish. We examine selenium:mercury molar ratios in freshwater fish from Tennessee at Poplar Creek which receives ongoing inputs of mercury from the Department of Energy’s Oak Ridge Y-12 facility. Our objective was to determine variation of the ratios within species that might affect the protectiveness of selenium against mercury toxicity. Within species, the ratio was correlated significantly and positively with fish length only for two species. There was great individual variation in the selenium:mercury molar ratio within each species, except striped bass. The lack of a clear relationship between the selenium:mercury molar ratio and fish length, and the intraspecific variation, suggests that it would be difficult to use the molar ratio in predicting either the risk from mercury toxicity or in devising consumption advisories. PMID:22456727

Burger, Joanna; Gochfeld, Michael; Jeitner, C.; Donio, M.; Pittfield, T.

2014-01-01

107

The Freshwater Sponge Ephydatia fluviatilis Harbours Diverse Pseudomonas Species (Gammaproteobacteria, Pseudomonadales) with Broad-Spectrum Antimicrobial Activity  

PubMed Central

Bacteria are believed to play an important role in the fitness and biochemistry of sponges (Porifera). Pseudomonas species (Gammaproteobacteria, Pseudomonadales) are capable of colonizing a broad range of eukaryotic hosts, but knowledge of their diversity and function in freshwater invertebrates is rudimentary. We assessed the diversity, structure and antimicrobial activities of Pseudomonas spp. in the freshwater sponge Ephydatia fluviatilis. Polymerase Chain Reaction – Denaturing Gradient Gel Electrophoresis (PCR-DGGE) fingerprints of the global regulator gene gacA revealed distinct structures between sponge-associated and free-living Pseudomonas communities, unveiling previously unsuspected diversity of these assemblages in freshwater. Community structures varied across E. fluviatilis specimens, yet specific gacA phylotypes could be detected by PCR-DGGE in almost all sponge individuals sampled over two consecutive years. By means of whole-genome fingerprinting, 39 distinct genotypes were found within 90 fluorescent Pseudomonas isolates retrieved from E. fluviatilis. High frequency of in vitro antibacterial (49%), antiprotozoan (35%) and anti-oomycetal (32%) activities was found among these isolates, contrasting less-pronounced basidiomycetal (17%) and ascomycetal (8%) antagonism. Culture extracts of highly predation-resistant isolates rapidly caused complete immobility or lysis of cells of the protozoan Colpoda steinii. Isolates tentatively identified as P. jessenii, P. protegens and P. oryzihabitans showed conspicuous inhibitory traits and correspondence with dominant sponge-associated phylotypes registered by cultivation-independent analysis. Our findings suggest that E. fluviatilis hosts both transient and persistent Pseudomonas symbionts displaying antimicrobial activities of potential ecological and biotechnological value. PMID:24533086

Keller-Costa, Tina; Jousset, Alexandre; van Overbeek, Leo; van Elsas, Jan Dirk; Costa, Rodrigo

2014-01-01

108

The freshwater sponge Ephydatia fluviatilis harbours diverse Pseudomonas species (Gammaproteobacteria, Pseudomonadales) with broad-spectrum antimicrobial activity.  

PubMed

Bacteria are believed to play an important role in the fitness and biochemistry of sponges (Porifera). Pseudomonas species (Gammaproteobacteria, Pseudomonadales) are capable of colonizing a broad range of eukaryotic hosts, but knowledge of their diversity and function in freshwater invertebrates is rudimentary. We assessed the diversity, structure and antimicrobial activities of Pseudomonas spp. in the freshwater sponge Ephydatia fluviatilis. Polymerase Chain Reaction--Denaturing Gradient Gel Electrophoresis (PCR-DGGE) fingerprints of the global regulator gene gacA revealed distinct structures between sponge-associated and free-living Pseudomonas communities, unveiling previously unsuspected diversity of these assemblages in freshwater. Community structures varied across E. fluviatilis specimens, yet specific gacA phylotypes could be detected by PCR-DGGE in almost all sponge individuals sampled over two consecutive years. By means of whole-genome fingerprinting, 39 distinct genotypes were found within 90 fluorescent Pseudomonas isolates retrieved from E. fluviatilis. High frequency of in vitro antibacterial (49%), antiprotozoan (35%) and anti-oomycetal (32%) activities was found among these isolates, contrasting less-pronounced basidiomycetal (17%) and ascomycetal (8%) antagonism. Culture extracts of highly predation-resistant isolates rapidly caused complete immobility or lysis of cells of the protozoan Colpoda steinii. Isolates tentatively identified as P. jessenii, P. protegens and P. oryzihabitans showed conspicuous inhibitory traits and correspondence with dominant sponge-associated phylotypes registered by cultivation-independent analysis. Our findings suggest that E. fluviatilis hosts both transient and persistent Pseudomonas symbionts displaying antimicrobial activities of potential ecological and biotechnological value. PMID:24533086

Keller-Costa, Tina; Jousset, Alexandre; van Overbeek, Leo; van Elsas, Jan Dirk; Costa, Rodrigo

2014-01-01

109

First evidence of "paralytic shellfish toxins" and cylindrospermopsin in a Mexican freshwater system, Lago Catemaco, and apparent bioaccumulation of the toxins in "tegogolo" snails (Pomacea patula catemacensis).  

PubMed

Exposure to cyanobacterial toxins in freshwater systems, including both direct (e.g., drinking water) and indirect (e.g., bioaccumulation in food webs) routes, is emerging as a potentially significant threat to human health. We investigated cyanobacterial toxins, specifically cylindrospermopsin (CYN), the microcystins (MCYST) and the "paralytic shellfish toxins" (PST), in Lago Catemaco (Veracruz, Mexico). Lago Catemaco is a tropical lake dominated by Cylindrospermopsis, specifically identified as Cylindrospermopsis catemaco and Cylindrospermopsis philippinensis, and characterized by an abundant, endemic species of snail (Pomacea patula catemacensis), known as "tegogolos," that is both consumed locally and commercially important. Samples of water, including dissolved and particulate fractions, as well as extracts of tegogolos, were screened using highly specific and sensitive ELISA. ELISA identified CYN and PST at low concentrations in only one sample of seston; however, both toxins were detected at appreciable quantities in tegogolos. Calculated bioaccumulation factors (BAF) support bioaccumulation of both toxins in tegogolos. The presence of CYN in the phytoplankton was further confirmed by HPLC-UV and LC-MS, following concentration and extraction of algal cells, but the toxin could not be confirmed by these methods in tegogolos. These data represent the first published evidence for CYN and the PST in Lago Catemaco and, indeed, for any freshwater system in Mexico. Identification of the apparent bioaccumulation of these toxins in tegogolos may suggest the need to further our understanding of the transfer of cyanobacterial toxins in freshwater food webs as it relates to human health. PMID:19651152

Berry, John P; Lind, Owen

2010-05-01

110

COMPARISON OF FOUR DNA EXTRACTION METHODS FROM INVASIVE FRESHWATER BIVALVE SPECIES (MOLLUSCA: BIVALVIA) IN ROMANIAN FAUNA  

Microsoft Academic Search

In this paper we propose an evaluation of four DNA extraction methods in terms of DNA quantity, quality and success of the subsequent PCR amplifications of nuclear and mitochondrial loci. Individuals from the following freshwater invasive mussels in Romania were used to asses the efficiency of the DNA extraction methods: Dreissena polymorpha, Dreissena bugensis, Sinanodonta woodiana and Corbicula fluminea. While

OANA PAULA POPA; DUMITRU MURARIU; LUIS OVIDIU POPA

2007-01-01

111

Susceptibility of various Japanese freshwater fish species to an isolate of viral haemorrhagic septicaemia virus (VHSV) genotype IVb.  

PubMed

Genotype IVb of viral haemorrhagic septicaemia virus (VHSV) was isolated for the first time in the Great Lakes basin in 2003, where it spread and caused mass mortalities in several wild fish species throughout the basin. In order to prevent further spreading of the disease and to assess risks of new genotypes invading new watersheds, basic microbiological information such as pathogenicity studies are essential. In this study, experimental infections were conducted on 7 indigenous freshwater fish species from Japan by immersion with a VHSV genotype IVb isolate. In Expt 1, cumulative mortalities in bluegill Lepomis macrochirus used as positive controls, Japanese fluvial sculpin Cottus pollux, and iwana Salvelinus leucomaenis pluvius were 50, 80 and 0%, respectively. In Expt 2, cumulative mortalities of 100, 100 and 10% were observed in Japanese fluvial sculpin C. pollux, Japanese rice fish Oryzias latipes and yoshinobori Rhinogobius sp., respectively. No mortality was observed in honmoroko Gnathopogon caerulescens, akaza Liobagrus reini or Japanese striped loach Cobitis biwae. VHSV was detected by RT-PCR from samples of kidney, spleen, and brain from all dead fish, and virus re-isolation by cell culture was successful from all dead fish. We detected the virus in the brain from a few surviving bluegill 50 d post exposure by both cell culture and RT-PCR. These results revealed that VHSV IVb could become a serious threat to wild freshwater fish species in Japan, and that some surviving fish might become healthy carriers of the virus. PMID:24270018

Ito, Takafumi; Olesen, Niels Jørgen

2013-11-25

112

Antioxidative stress response of Lepidium sativum due to exposure to cyanobacterial secondary metabolites  

Microsoft Academic Search

Agricultural plants can come in contact with cyanobacterial toxins via spray irrigation techniques. After uptake in the plants, cyanobacterial toxins are able to induce oxidative stress via the enhanced production of reactive oxygen species. If the initiated oxidation processes proceeds uninhibited, extensive cellular damage might occur like DNA damage, protein inhibition or lipid peroxidation. The results provide further evidence that

Julian Stüven; Stephan Pflugmacher

2007-01-01

113

Variation of Microcystins, Cyanobacterial Hepatotoxins, in Anabaena spp. as a Function of Growth Stimuli  

Microsoft Academic Search

Cyanobacterial hepatotoxins, microcystins, are specific inhibitors of serine\\/threonine protein phosphatases and potent tumor promoters. They have caused several poisonings of animals and also pose a health hazard for humans through the use of water for drinking and recreation. Different strains of the same cyanobacterial species may variously be nontoxic, be neurotoxic, or produce several microcystin variants. It is poorly under-

JARKKO RAPALA; KAARINA SIVONEN; CHRISTINA LYRA; SEPPO I. NIEMELA

1997-01-01

114

Insights into the Ecology and Genetics of Lichens with a Cyanobacterial  

E-print Network

Insights into the Ecology and Genetics of Lichens with a Cyanobacterial Photobiont Katja Fedrowitz into the Ecology and Genetics of Lichens with a Cyanobacterial Photobiont Abstract Nature conservation requires in the different phases of a species life. In lichens, these phases comprise dispersal, establishment, and growth

115

A new species of freshwater crab of the genus Microthelphusa Pretzmann, 1968 (Crustacea: Brachyura: Pseudothelphusidae) from the Amazon region of Guyana.  

PubMed

A new species of freshwater crab, Microthelphusa furcifer, is described and illustrated from the Potaro-Siparuni Kuribrong River in the Guyana Shield (Amazon region of Guyana). The new species can be easily separated from its congeners by the morphology of the first gonopod. The first gonopod of Microthelphusa meansi Cumberlidge, 2007, is illustrated to clarify some aspects of its morphology.  PMID:25112338

Pedraza, Manuel; Tavares, Marcos

2014-01-01

116

Susceptibility to freshwater acidification by two species of loon: Red-throated Loon (Gavia stellata) and Arctic Loon (Gavia arctica) in southwest Sweden  

Microsoft Academic Search

In southwest Sweden, the two species of loon, Gavia stellata and G. arctica, have shown different trends in population size and production of young during the last decades. Both species fish in oligotrophic freshwaters, susceptible to acidification. The number of breeding sites occupied by G. stellata has been reduced by almost 50% during the last 40–50 years. For G. arctica,

Mats O. G. Eriksson

1994-01-01

117

Variations in the endemic fish assemblage of a global freshwater ecoregion: Associations with introduced species in cascading reservoirs  

NASA Astrophysics Data System (ADS)

The present study aimed at assessing spatial and temporal changes in the composition and structure of an endemic fish assemblage and the possible associations with introduces species in a system of cascading reservoirs, in Iguaçu River, state of Paraná, southern Brazil. We collected 135,639 specimens: 131,716 individuals of endemic species and 3923 of introduced species. The most abundant introduced species were: Odontesthes bonariensis (85.1%), Prochilodus lineatus (7.5%) and Tilapia rendalli (4.9%). Significant spatial and temporal differences in richness were observed for both endemic and introduced species. The composition and structure of the assemblage of endemic and introduced fish exhibited significant spatial differences. The Procrustes analysis showed a significant spatial association between composition and structure of the assemblage of endemic and introduced fish in Iguaçu River. Changes in the endemic fish assemblage of Iguaçu River related to the establishment of introduced species and to habitat changes caused by cascading reservoirs enable advancing knowledge on environmental impacts in freshwater ecoregions.

Daga, Vanessa S.; Gubiani, Éder A.

2012-05-01

118

A new species of freshwater mussel (Bivalvia: Unionidae), Pleurobema athearni, from the Coosa River Drainage of Alabama, USA  

USGS Publications Warehouse

The Mobile Basin historically supported one of the most diverse freshwater mussel (Bivalvia: Unionidae) assemblages in North America. More than 65 species of mussels are known from the Basin, but it is difficult to determine how many species were present historically. The drainage's unique physical habitat was largely destroyed between the late 1800s and mid-1900s by impoundment and channel modifications of most of the larger rivers. Many species that were once common are now restricted to small headwater rivers and mid-sized tributaries. Recent Coosa River tributary surveys revealed a new, undescribed species of Pleurobema. This new species, Pleurobema athearni, is distinctive in outward appearance, shell morphometry and reproductive morphology, and can be distinguished from other Coosa River drainage unionids. Our analysis indicates that P. athearni is morphologically different from other similar taxa. It differs both in shell width/length and width/height ratios and thus provides a simple, quantitative means to differentiate this species from P. georgianum (Lea, 1841) Fusconaia barnesiana (Lea, 1838), and F. cerina (Conrad, 1838), which it superficially resembles and that also occur in the area. Our morphological diagnosis of this species is supported by recent molecular analyses that suggest this species is a Pleurobema and one closely related to other endemic Coosa River drainage unionids. The discovery of a new species of large, long-lived macroinvertebrate from a relatively well-sampled drainage in a populated region of the southeast United States underscores the need for more detailed surveys in isolated stretches of tributary streams. It should also serve as a reminder that almost 40 species of aquatic mollusks have been extirpated from the Mobile Basin before anything could be learned about their habitat or life history requirements. Copyright ?? 2006 Magnolia Press.

Gangloff, M.M.; Williams, J.D.; Feminella, J.W.

2006-01-01

119

Local nutrient regimes determine site-specific environmental triggers of cyanobacterial and microcystin variability in urban lakes  

NASA Astrophysics Data System (ADS)

Toxic cyanobacterial blooms in urban lakes present serious health hazards to humans and animals and require effective management strategies. In the management of toxic cyanobacteria blooms, understanding the roles of environmental factors is crucial. To date, a range of environmental factors have been proposed as potential triggers for the spatiotemporal variability of cyanobacterial biomass and microcystins in freshwater systems. However, the environmental triggers of cyanobacteria and microcystin variability remain a subject of debate due to contrasting findings. This issue has raised the question if the environmental triggers are site-specific and unique between water bodies. In this study, we investigated the site-specificity of environmental triggers for cyanobacterial bloom and cyanotoxins dynamics. Our study suggests that cyanobacterial dominance and cyanobacterial microcystin content variability were significantly correlated to phosphorus and iron concentrations. However, the correlations between phosphorus and iron with cyanobacterial biomass and microcystin variability were not consistent between lakes, thus suggesting a site specificity of these environmental factors. The discrepancies in the correlations could be explained by differences in local nutrient concentration and the cyanobacterial community in the systems. The findings of this study suggest that identification of site-specific environmental factors under unique local conditions is an important strategy to enhance positive outcomes in cyanobacterial bloom control measures.

Sinang, S. C.; Reichwaldt, E. S.; Ghadouani, A.

2014-10-01

120

Rapid evolution of sessility in an endemic species flock of the freshwater bivalve Corbicula from ancient lakes on Sulawesi, Indonesia  

PubMed Central

The fauna of ancient lakes frequently contains taxa with highly derived morphologies that resulted from in situ radiation of lacustrine lineages with high antiquity. We employed a molecular mtDNA phylogeny to investigate this claim for corbiculid freshwater bivalves in two ancient lake systems on the Indonesian island Sulawesi. Among the otherwise mobile corbiculid species flock, only one taxon, Posostrea anomioides, in the ancient Lake Poso exhibits a unique habit, i.e. cementing one valve to the substrate. Our data show that Corbicula on Sulawesi is polyphyletic, with the endemic riverine taxa in terminal position, and the lacustrine species flock being paraphyletic. Surprisingly, Posostrea is not confirmed as a genus distinct from Corbicula and genetic distances suggest a rather recent origin from the only other corbiculid species endemic to Lake Poso, the non-cementing Corbicula possoensis. While the cementing anomioides, despite its unique behavioural and morphological characteristics, clusters together with non-sessile Corbicula species, the latter exhibit strong genetic distances in the absence of morphological disparity and fall into several genetically rather distinct clades. These findings suggest that developmental plasticity of animals in ancient lakes rather than the antiquity of lineages might account for the unique morphology of some species. PMID:17148330

von Rintelen, Thomas; Glaubrecht, Matthias

2005-01-01

121

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

SciTech Connect

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 at the contaminated site, and single-strand breaks in liver DNA. The integrity of the DNA was examined by the alkaline unwinding assay, a technique that detects strand breaks as a biological marker of possible exposure to genotoxic agents. This measure of DNA damage was significantly increased in both species of turtles at the contaminated site compared with turtles of the same species at a reference site, and shows that contaminant-exposed populations were under more severe genotoxic stress than those at the reference site. The level of strand breaks observed at the contaminated site was high and in the range reported for other aquatic species exposed to deleterious concentrations of genotoxic agents such as chemicals and ionizing radiation. Statistically significantly higher concentrations of radionuclides and Hg were detected in the turtles from the contaminated area. Mercury concentrations were significantly higher in the more carnivorous snapping turtle compared with the slider; however, both species were effective monitors of the contaminants.

Meyers-Schoene, L. (Univ. of Tennessee, Knoxville, TN (United States)); Shugart, L.R.; Beauchamp, J.J.; Walton, B.T. (Oak Ridge National Lab., TN (United States))

1993-08-01

122

Long-term culture at elevated atmospheric CO2 fails to evoke specific adaptation in seven freshwater phytoplankton species  

PubMed Central

The concentration of CO2 in the atmosphere is expected to double by the end of the century. Experiments have shown that this will have important effects on the physiology and ecology of photosynthetic organisms, but it is still unclear if elevated CO2 will elicit an evolutionary response in primary producers that causes changes in physiological and ecological attributes. In this study, we cultured lines of seven species of freshwater phytoplankton from three major groups at current (approx. 380 ppm CO2) and predicted future conditions (1000 ppm CO2) for over 750 generations. We grew the phytoplankton under three culture regimes: nutrient-replete liquid medium, nutrient-poor liquid medium and solid agar medium. We then performed reciprocal transplant assays to test for specific adaptation to elevated CO2 in these lines. We found no evidence for evolutionary change. We conclude that the physiology of carbon utilization may be conserved in natural freshwater phytoplankton communities experiencing rising atmospheric CO2 levels, without substantial evolutionary change. PMID:23303540

Low-Décarie, Etienne; Jewell, Mark D.; Fussmann, Gregor F.; Bell, Graham

2013-01-01

123

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)

1997-10-01

124

Comparison of cyanobacterial microcystin synthetase (mcy) E gene transcript levels, mcy E gene copies, and biomass as indicators of microcystin risk under laboratory and field conditions  

PubMed Central

Increased incidences of mixed assemblages of microcystin-producing and nonproducing cyanobacterial strains in freshwater bodies necessitate development of reliable proxies for cyanotoxin risk assessment. Detection of microcystin biosynthetic genes in water blooms of cyanobacteria is generally indicative of the presence of potentially toxic cyanobacterial strains. Although much effort has been devoted toward elucidating the microcystin biosynthesis mechanisms in many cyanobacteria genera, little is known about the impacts of co-occurring cyanobacteria on cellular growth, mcy gene expression, or mcy gene copy distribution. The present study utilized conventional microscopy, qPCR assays, and enzyme-linked immunosorbent assay to study how competition between microcystin-producing Microcystis aeruginosa CPCC 299 and Planktothrix agardhii NIVA-CYA 126 impacts mcyE gene expression, mcyE gene copies, and microcystin concentration under controlled laboratory conditions. Furthermore, analyses of environmental water samples from the Missisquoi Bay, Quebec, enabled us to determine how the various potential toxigenic cyanobacterial biomass proxies correlated with cellular microcystin concentrations in a freshwater lake. Results from our laboratory study indicated significant downregulation of mcyE gene expression in mixed cultures of M. aeruginosa plus P. agardhii on most sampling days in agreement with depressed growth recorded in the mixed cultures, suggesting that interaction between the two species probably resulted in suppressed growth and mcyE gene expression in the mixed cultures. Furthermore, although mcyE gene copies and McyE transcripts were detected in all laboratory and field samples with measureable microcystin levels, only mcyE gene copies showed significant positive correlations (R2 > 0.7) with microcystin concentrations, while McyE transcript levels did not. These results suggest that mcyE gene copies are better indicators of potential risks from microcystins than McyE transcript levels or conventional biomass proxies, especially in water bodies comprising mixed assemblages of toxic and nontoxic cyanobacteria. PMID:24838591

Ngwa, Felexce F; Madramootoo, Chandra A; Jabaji, Suha

2014-01-01

125

Use of chemical communication in the management of freshwater aquatic species that are vectors of human diseases or are invasive.  

PubMed

Chemical communication occurs when both originator (signaller) and one or more receiver(s) possess specializations for chemical exchange of information. Chemical information can be used by a wide variety of species to locate food and mates, avoid predators and engage in social interactions. In this review, we focus on chemical signalling between mates or cues from nest sites or hosts by selected aquatic pest species and indicate how chemical information can be used to manage pests. The pests are vectors of disease (blood-sucking insects) or invasive species (crayfishes and fishes) that have exhibited detrimental effects on indigenous species. Pheromones released by females attract and stimulate males in some taxa (insects, crayfish, goldfish, and crucian carp), whereas pheromones released by males attract females in others (round goby, sea lamprey). Other chemicals (e.g., habitat odours or odours given off by developmental stages of conspecifics) can affect oviposition decisions of pest species. In areas of aquatic environments where other cues may be limited (e.g., visual), freshwater organisms may rely solely on chemical signals or in concert with environmental cues for reproduction. Once the chemical structure of odour attractants are identified and shown to lure conspecifics to traps, odorants or their blends can be used to control the aquatic pests. There is promise for the application of pheromone traps to control the malarian vector (Anopheles gambiae) or invasive species such as signal crayfish (Pacifastacus leniusculus), sea lamprey (Petromyzon marinus) and the round goby (Neogobius melanostomus) by disrupting the reproductive behaviours of these species. PMID:17367788

Corkum, Lynda D; Belanger, Rachelle M

2007-01-01

126

Comparing Band Ratio, Semi-Empirical, and Modified Gaussian Models in Predicting Cyanobacterial Pigments in Eutrophic Inland Waters  

NASA Astrophysics Data System (ADS)

Cyanobacteria are known to produce toxins harmful to humans and compounds that alter the taste/odor of water. Monitoring cyanobacteria is of interest to surface water managers because eutrophication of these surface water bodies are common thus increasing the chances of cyanobacterial blooms. Traditionally cyanobacteria are remotely sensed using the spectral properties of the two pigments: chlorophyll a (Chl-a), indicative of all algal and cyanobacteria species, and phycocyanin (PC), specific to cyanobacteria in most freshwater systems. Initial algorithms identifying cyanobacterial pigments used ratios of reflectance at specific wavelengths. In an effort to increase transferability between different systems researchers have included optical properties of water and water constituents to build semi-empirical models. Recently researchers have applied a curve-fitting, modified Gaussian model (MGM), to predict these cyanobacterial pigments. To determine the best performing algorithm this study compares the performance of 4 band ratio, 4 semi-empirical, and 2 modified Gaussian models in predicting PC and Chl-a on three central Indiana reservoirs (Eagle Creek, Geist, Morse). For each of these reservoirs, spectral data were collected with three different sensors (boat-based: ASD Fieldspec, Ocean Optics USB4000; Ariel: AISA Eagle) over a three year period (2005-2007), and water samples concomitant with these spectra were analyzed for concentration of the two pigments and other water constituents. Comparison shows that a model using the MGM strength at 620 nm from a 2005 Morse Reservoir ASD Fieldspec data set shows that the MGM has the best transferability to a 2006 Morse Reservoir ASD Fieldspec data set in predicting phycocyanin (R2 = 0.77; RMSE= 52.45 ppb), and a band ratio model published by Mittenzwey et al. 1991 has the best transferability in predicting chlorophyll a (R2 = 0.74; RMSE 16.31=ppb).

Robertson, A. L.; Lin, L.; Tedesco, L.; Wilson, J.; Soyeux, E.

2008-12-01

127

Impact on indigenous species biodiversity caused by the globalisation of alien recreational freshwater fisheries  

Microsoft Academic Search

One of the most insidious threats to fish conservation around the world is deliberate or accidental introduction of fish species. The impact of alien invasive sport fish is for the most part unpredictable in time and space, with the introduction of relatively few species having resulted in many extirpations of indigenous fish species worldwide. More nations need to quantify biodiversity

J. A. Cambray

2003-01-01

128

Replacement names and nomenclatural comments for problematic species-group names in Europe's Neogene freshwater Gastropoda.  

PubMed

Over the last 250 years of taxonomic descriptions of freshwater gastropods a large number of primary and secondary homonyms were produced. Several of them have now been uncovered in the course of a new database project. To overcome the associated nomenclatural problems we propose 10 replacement names: Theodoxus pseudodacicus nom. nov., Theodoxus stoicai nom. nov., Viviparus deleeuwi nom. nov., Viviparus lubenescuae nom. nov., Viviparus wesselinghi nom. nov., Melanopsis anistratenkoi nom. nov., Melanopsis gearyae nom. nov., Melanopsis magyari nom. nov., Melanopsis vrcinensis nom. nov., and Pyrgula rusti nom. nov. Additionally, we discuss taxa that might become secondary homonyms because of uncertain genus attributions. The genera Melanoptychia Neumayr, 1880 and Boistelia Cossmann, 1909 are synonymized with Melanopsis Férussac, 1807 in Férussac & Férussac, 1807 based on the lack of sufficient separation criteria. Involved combinations are expounded and recombined accordingly. The nomenclatural problems regarding Melanopsis costata Fuchs, 1870 (non Olivier, 1804) and Planorbis varians Fuchs, 1870 sensu Bandel (2010) are discussed. PMID:24872237

Neubauer, Thomas A; Harzhauser, Mathias; Georgopoulou, Elisavet; Mandic, Oleg; Kroh, Andreas

2014-01-01

129

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.

2010-04-01

130

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...

131

Freshwater fishes of Patagonia in the 21st Century after a hundred years of human settlement, species introductions, and environmental change  

Microsoft Academic Search

We review the status of the freshwater fish fauna of Patagonia, an assemblage with 26 native species, comprising fishes of Gondwanan origin, marine dispersants, and oceanic elements of local origin. Several processes, old and new, have shaped the landscape of Patagonia and its fauna: a Gondwanan heritage, the Andes uplifting, Pleistocene ice, volcanic activity, introduction of exotic fishes, mostly Salmonids,

Miguel A. Pascual; V ´ ictor Cussac; Brian Dyer; Doris Soto; Pablo Vigliano; Silvia Ortubay; Patricio Macchi

2007-01-01

132

Genetic diversity in cyanobacterial symbionts of thalloid bryophytes  

Microsoft Academic Search

Two species of thalloid liverworts, Blasia pusilla and Cavicularia densa, form stable symbioses with nitro- gen-fixing cyanobacteria. Both bryophytes promote the persistence of their cyanobacterial associations by producing specialized gemmae, which facilitate the simultaneous dispersal of the host and its nitrogen- fixing symbionts. Here the genetic diversity of cyano- bacterial symbionts of Blasia and Cavicularia is examined. The results indicate

Jouko Rikkinen; Viivi Virtanen

2010-01-01

133

Fungal Parasitism: Life Cycle, Dynamics and Impact on Cyanobacterial Blooms  

E-print Network

Fungal Parasitism: Life Cycle, Dynamics and Impact on Cyanobacterial Blooms Me´lanie Gerphagnon Abstract Many species of phytoplankton are susceptible to parasitism by fungi from the phylum Chytridiomycota (i.e. chytrids). However, few studies have reported the effects of fungal parasites on filamentous

Paris-Sud XI, Université de

134

Toxicity of magnesium pulses to tropical freshwater species and the development of a duration-based water quality guideline.  

PubMed

Six freshwater species (Chlorella sp., Lemna aequinoctialis, Amerianna cumingi, Hydra viridissima, Moinodaphnia macleayi, and Mogurnda mogurnda) were exposed to 4-h, 8-h, and 24-h Mg pulses in natural creek water. Magnesium toxicity to all species increased with exposure duration; however, the extent of increase and the nature of the relationship differed greatly between species. Based on median inhibitory concentrations (IC50s), and compared with continuous exposure data from a previous study, the increase in toxicity with increasing exposure duration from 4 h to continuous (72-144 h) ranged from approximately 2-fold for Chlorella sp. and H. viridissima to greater than 40-fold for A. cumingi. Moreover, the form of the relationship between Mg toxicity and duration ranged from linear or near-linear to exponential for different species. The life-stage at which M. macleayi was exposed was important, with cladocerans pulsed at the onset of reproductive maturity being approximately 4 times more sensitive (based on IC50s) than younger than 6-h-old neonates. Species sensitivity distributions were constructed for the 4-h, 8-h, and 24-h pulse durations, from which 99% species protection guideline values (95% confidence limits [CLs]) of 94 (6.4-1360) mg/L, 14 (0.5-384) mg/L, and 8.0 (0.5-144) mg/L Mg, respectively, were derived. These values were plotted against exposure duration (h) and polynomial interpolation used to derive a guideline value for any pulse duration within the range assessed. PMID:23613126

Hogan, Alicia C; Trenfield, Melanie A; Harford, Andrew J; van Dam, Rick A

2013-09-01

135

Cyanobacterial precipitation of gypsum, calcite, and magnesite from natural alkaline lake water  

NASA Astrophysics Data System (ADS)

Results from transmission electron microscopy provide direct evidence for cyanobacterial biomineralization of gypsum and calcite in aquatic environments. Laboratory simulations using filter-sterilized natural lake water inoculated with Synechococcus sp., isolated from Fayette ville Green Lake, New York, revealed epicellular biomineralization of gypsum, calcite, and magnesite. Experimental, electron microscopical, and sedimentological evidence indicates that Synechococcus is responsible for a major proportion of the marl sediment and carbonate bioherms in Green Lake. The elucidated role of Synechococcus in biomineralization and its ubiquitous distribution in nature have widespread implications for cyanobacterial mineralization in marine and freshwater environments since late Archean time.

Thompson, J. B.; Ferris, F. G.

1990-10-01

136

Site history and edaphic features override the influence of plant species on microbial communities in restored tidal freshwater wetlands.  

PubMed

Restored wetland soils differ significantly in physical and chemical properties from their natural counterparts even when plant community compositions are similar, but effects of restoration on microbial community composition and function are not well understood. Here, we investigate plant-microbe relationships in restored and natural tidal freshwater wetlands from two subestuaries of the Chesapeake Bay. Soil samples were collected from the root zone of Typha latifolia, Phragmites australis, Peltandra virginica, and Lythrum salicaria. Soil microbial composition was assessed using 454 pyrosequencing, and genes representing bacteria, archaea, denitrification, methanogenesis, and methane oxidation were quantified. Our analysis revealed variation in some functional gene copy numbers between plant species within sites, but intersite comparisons did not reveal consistent plant-microbe trends. We observed more microbial variations between plant species in natural wetlands, where plants have been established for a long period of time. In the largest natural wetland site, sequences putatively matching methanogens accounted for ?17% of all sequences, and the same wetland had the highest numbers of genes coding for methane coenzyme A reductase (mcrA). Sequences putatively matching aerobic methanotrophic bacteria and anaerobic methane-oxidizing archaea (ANME) were detected in all sites, suggesting that both aerobic and anaerobic methane oxidation are possible in these systems. Our data suggest that site history and edaphic features override the influence of plant species on microbial communities in restored wetlands. PMID:25769832

Prasse, Christine E; Baldwin, Andrew H; Yarwood, Stephanie A

2015-05-15

137

Water economy of three Cinclodes (Furnariidae) species inhabiting marine and freshwater ecosystems  

Microsoft Academic Search

Birds living in desert environments have been the preferred models for the study of physiological adaptations to water scarcity. Passerine birds living in marine coastal habitats face similar problems, yet physiological adaptations to water conservation in such species have been poorly documented. We measured total evaporative water loss (TEWL) and rates of oxygen consumption (VO2) in three species of passerine

PABLO SABAT; ROBERTO F. NESPOLO; FRANCISCO BOZINOVIC

2004-01-01

138

ERPOBDELLA LAHONTANA (ANNELIDA: HIRUDINEA: ARHYNCHOBDELLIDA: ERPOBDELLIDAE), A NEW SPECIES OF FRESHWATER LEECH FROM NORTH AMERICA  

EPA Science Inventory

New species of a leech, Erpobdella lahontana, is described from the Lahontan Basin in California and Nevada of the western United States. This species has four pairs of eyes, the preatrial loops of male paired ducts extend to ganglion XI, and the male and female gonopores are loc...

139

Habitat Fragmentation and Species Extirpation in Freshwater Ecosystems; Causes of Range Decline of the Indus River Dolphin (Platanista gangetica minor)  

PubMed Central

Habitat fragmentation of freshwater ecosystems is increasing rapidly, however the understanding of extinction debt and species decline in riverine habitat fragments lags behind that in other ecosystems. The mighty rivers that drain the Himalaya - the Ganges, Brahmaputra, Indus, Mekong and Yangtze - are amongst the world’s most biodiverse freshwater ecosystems. Many hundreds of dams have been constructed, are under construction, or are planned on these rivers and large hydrological changes and losses of biodiversity have occurred and are expected to continue. This study examines the causes of range decline of the Indus dolphin, which inhabits one of the world’s most modified rivers, to demonstrate how we may expect other vertebrate populations to respond as planned dams and water developments come into operation. The historical range of the Indus dolphin has been fragmented into 17 river sections by diversion dams; dolphin sighting and interview surveys show that river dolphins have been extirpated from ten river sections, they persist in 6, and are of unknown status in one section. Seven potential factors influencing the temporal and spatial pattern of decline were considered in three regression model sets. Low dry-season river discharge, due to water abstraction at irrigation barrages, was the principal factor that explained the dolphin’s range decline, influencing 1) the spatial pattern of persistence, 2) the temporal pattern of subpopulation extirpation, and 3) the speed of extirpation after habitat fragmentation. Dolphins were more likely to persist in the core of the former range because water diversions are concentrated near the range periphery. Habitat fragmentation and degradation of the habitat were inextricably intertwined and in combination caused the catastrophic decline of the Indus dolphin. PMID:25029270

Braulik, Gill T.; Arshad, Masood; Noureen, Uzma; Northridge, Simon P.

2014-01-01

140

Habitat fragmentation and species extirpation in freshwater ecosystems; causes of range decline of the Indus river dolphin (Platanista gangetica minor).  

PubMed

Habitat fragmentation of freshwater ecosystems is increasing rapidly, however the understanding of extinction debt and species decline in riverine habitat fragments lags behind that in other ecosystems. The mighty rivers that drain the Himalaya - the Ganges, Brahmaputra, Indus, Mekong and Yangtze - are amongst the world's most biodiverse freshwater ecosystems. Many hundreds of dams have been constructed, are under construction, or are planned on these rivers and large hydrological changes and losses of biodiversity have occurred and are expected to continue. This study examines the causes of range decline of the Indus dolphin, which inhabits one of the world's most modified rivers, to demonstrate how we may expect other vertebrate populations to respond as planned dams and water developments come into operation. The historical range of the Indus dolphin has been fragmented into 17 river sections by diversion dams; dolphin sighting and interview surveys show that river dolphins have been extirpated from ten river sections, they persist in 6, and are of unknown status in one section. Seven potential factors influencing the temporal and spatial pattern of decline were considered in three regression model sets. Low dry-season river discharge, due to water abstraction at irrigation barrages, was the principal factor that explained the dolphin's range decline, influencing 1) the spatial pattern of persistence, 2) the temporal pattern of subpopulation extirpation, and 3) the speed of extirpation after habitat fragmentation. Dolphins were more likely to persist in the core of the former range because water diversions are concentrated near the range periphery. Habitat fragmentation and degradation of the habitat were inextricably intertwined and in combination caused the catastrophic decline of the Indus dolphin. PMID:25029270

Braulik, Gill T; Arshad, Masood; Noureen, Uzma; Northridge, Simon P

2014-01-01

141

Biochemical and biophysical CO2 concentrating mechanisms in two species of freshwater macrophyte within the genus Ottelia (Hydrocharitaceae).  

PubMed

Two freshwater macrophytes, Ottelia alismoides and O. acuminata, were grown at low (mean 5 ?mol L(-1)) and high (mean 400 ?mol L(-1)) CO2 concentrations under natural conditions. The ratio of PEPC to RuBisCO activity was 1.8 in O. acuminata in both treatments. In O. alismoides, this ratio was 2.8 and 5.9 when grown at high and low CO2, respectively, as a result of a twofold increase in PEPC activity. The activity of PPDK was similar to, and changed with, PEPC (1.9-fold change). The activity of the decarboxylating NADP-malic enzyme (ME) was very low in both species, while NAD-ME activity was high and increased with PEPC activity in O. alismoides. These results suggest that O. alismoides might perform a type of C4 metabolism with NAD-ME decarboxylation, despite lacking Kranz anatomy. The C4-activity was still present at high CO2 suggesting that it could be constitutive. O. alismoides at low CO2 showed diel acidity variation of up to 34 ?equiv g(-1) FW indicating that it may also operate a form of crassulacean acid metabolism (CAM). pH-drift experiments showed that both species were able to use bicarbonate. In O. acuminata, the kinetics of carbon uptake were altered by CO2 growth conditions, unlike in O. alismoides. Thus, the two species appear to regulate their carbon concentrating mechanisms differently in response to changing CO2. O. alismoides is potentially using three different concentrating mechanisms. The Hydrocharitaceae have many species with evidence for C4, CAM or some other metabolism involving organic acids, and are worthy of further study. PMID:24203583

Zhang, Yizhi; Yin, Liyan; Jiang, Hong-Sheng; Li, Wei; Gontero, Brigitte; Maberly, Stephen C

2014-09-01

142

ACCURACY ASSESSMENTS OF AIRBORNE HYSPERSPECTRAL DATA FOR MAPPING OPPORTUNISTIC PLANT SPECIES IN FRESHWATER COASTAL WETLANDS  

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...

143

Cyanobacterial diversity and halotolerance in a variable hypersaline environment.  

PubMed

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

2008-04-01

144

Toxicity of ammonia to nine native New Zealand freshwater invertebrate species  

Microsoft Academic Search

The toxic concentration for un-ionized ammonia (NH3) was assessed for nine native New Zealand invertebrate species. The 96-h EC50 values at 15°C and pH 7.6 and pH 8.2 ranged from 0.18 to >0.8 g\\/m3 NH3. The rank of species sensitivity was: shrimp (Paratya curvirostris) (least) ˜ mayfly (Zephlebia dentata) ˜ stonefly (Zealandobius furcillatus) < Oligochaeta (Lumbriculus variegatus) < fingernail clam

C. W. Hickey; M. L. Vickers

1994-01-01

145

Benthic fish exhibit more plastic crypsis than non-benthic species in a freshwater spring  

Microsoft Academic Search

Cryptic coloration reduces the ability of predators to detect prey, but the plasticity of this defense varies. Some organisms\\u000a possess static and permanent cryptic coloration, whereas in other species color changes may be induced. Depending upon the\\u000a species, induced color changes may be reversible or irreversible. In this study, we examined a subtle, rapid, and reversible\\u000a crypsis in which small

Serena Cox; Sondra Chandler; Caroline Barron; Kirsten Work

2009-01-01

146

Arsenic concentration and speciation in five freshwater fish species from Back Bay near Yellowknife, NT, CANADA  

Microsoft Academic Search

The concentration of total arsenic and five different arsenic species [As(III), As(V), monomethylarsonic acid (MMA), dimethylarsenic\\u000a acid (DMA), and arsenobetaine (AsB)], were measured in the muscle, liver and gastrointestinal tract (GIT) of five different\\u000a fish species [lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum), northern pike (Esox lucius), white sucker (Catostomus commersoni) and longnose sucker (Catostomus catostomus)] from Back Bay, Great

Simone de Rosemond; Qianli Xie; Karsten Liber

2008-01-01

147

Spatial distribution of cryptic species diversity in european freshwater amphipods (Gammarus fossarum) as revealed by pyrosequencing.  

PubMed

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. PMID:21909373

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

2011-01-01

148

A survey of coccidian infections of freshwater fishes of Peninsular Malaysia, with descriptions of three species of Goussia Labbé, 1896 (Apicomplexa: Eimeriidae).  

PubMed

Ninety-five specimens of 14 freshwater fish species from small streams in the Kuala Terengganu district and the Lake Kenyir Reservoir, Malaysia, were surveyed for coccidian infections. Six fish species proved to be infected with apicomplexans belonging to the genus Goussia. In all of these fishes Goussia species were found in unsporulated and semisporulated stages. Oöcysts of four species inhabiting the intestinal epithelium became sporulated in tap-water within 24 hours. In two fish species sporulation failed and only unsporulated oöcysts were recorded in the intestine. Three of the intestinal species finishing sporulation proved to be new to science and were described as Goussia malayensis n. sp., G. bettae n. sp. and G. pogonognathi n. sp. from Apocheilus panchax, Betta splendens and Hemirhamphodon pogonognatus, respectively. The fourth species, found in Trichogaster pectoralis, was identified as G. trichogasteri Székely & Molnár, 1992, a species known from aquarium-cultured T. trichopterus. PMID:12815211

Molnár, K; Shaharom-Harrison, F; Székely, Cs

2003-05-01

149

Haemogregarine infections of three species of aquatic freshwater turtles from two sites in Costa Rica  

PubMed Central

Twenty-five black river turtles (Rhinoclemmys funerea) and eight white-lipped mud turtles (Kinosternon leucostomum) from Selva Verde, Costa Rica were examined for haemoparasites. Leeches identified as Placobdella multilineata were detected on individuals from both species. All turtles sampled were positive for intraerythrocytic haemogregarines (Apicomplexa:Adeleorina) and the average parasitemia of black river turtles (0.34% ± 0.07) was significantly higher compared to white-lipped mud turtles (0.05% ± 0.006). No correlation was found between parasitemia and relative body mass of either species or between black river turtles from the two habitats. In addition, one scorpion mud turtle (Kinosternon scorpioides) examined from La Pacifica, Costa Rica, was positive for haemogregarines (0.01% parasitemia). Interestingly, parasites of the scorpion mud turtle were significantly smaller than those from the other two species and did not displace the erythrocyte nucleus, whereas parasites from the other two species consistently displaced host cell nuclei and often distorted size and shape of erythrocytes. This is the first report of haemogregarines in turtles from Central America and of haemogregarines in K. leucostomum, K. scorpioides, and any Rhinoclemmys species. Additional studies are needed to better characterise and understand the ecology of these parasites. PMID:24533326

Rossow, John A.; Hernandez, Sonia M.; Sumner, Scarlett M.; Altman, Bridget R.; Crider, Caroline G.; Gammage, Mallory B.; Segal, Kristy M.; Yabsley, Michael J.

2013-01-01

150

Effect of temperature on photosynthesis-light response and growth of four phytoplankton species isolated from a tidal freshwater river  

USGS Publications Warehouse

Three cyanobacteria (Microcystis aeruginosa Kutz. emend. Elenkin, Merismopedia tenuissima Lemmermann, and Oscillatoria sp.) and one diatom (Aulacoseira granulata var. angustissima O. Mull. emend. Simonsen) were isolated from the tidal freshwater Potomac River and maintained at 23??C and 40 ??mol photons??m-2??s-1 on a 16:8 L:D cycle in unialgal culture. Photosynthetic parameters were determined in nutrient-replete cultures growing exponentially at 15, 20, 25, and 30??C by incubation with 14C at six light levels. P(B)(max) was strongly correlated with temperature over the entire range for the cyanobacteria and from 15 to 25??C for Aulacoseira, with Q10 ranging from 1.79 to 2.67. The ?? values demonstrated a less consistent temperature pattern. Photosynthetic parameters indicated an advantage for cyanobacteria at warmer temperatures and in light-limited water columns. P(B)(max) and I(k) values were generally lower than comparable literature and field values, whereas ?? was generally higher, consistent with a somewhat shade acclimated status of our cultures. Specific growth rate (??), as measured by chlorophyll change, was strongly influenced by temperature in all species. Oscillatoria had the highest ?? at all temperatures, joined at lower temperatures by Aulacoseira and at higher temperatures by Microcystis. Values of ?? for Aulacaseira were near the low end of the literature range for diatoms consistent with the light-limited status of the cultures. The cyanobacteria exhibited growth rates similar to those reported in other studies. Q10 for growth ranged from 1.71 for Aulacoseira to 4.16 for Microcystis. Growth rate was highly correlated with P(B)(max) for each species and the regression slope coefficients were very similar for three of the species.

Coles, J.F.; Jones, R.C.

2000-01-01

151

Retinoid-like activity and teratogenic effects of cyanobacterial exudates.  

PubMed

Retinoic acids and their derivatives have been recently identified by chemical analyses in cyanobacteria and algae. Given the essential role of retinoids for vertebrate development this has raised concerns about a potential risk for vertebrates exposed to retinoids during cyanobacterial blooms. Our study focuses on extracellular compounds produced by phytoplankton cells (exudates). In order to address the capacity for the production of retinoids or compounds with retinoid-like activity we compared the exudates of ten cyanobacteria and algae using in vitro reporter gene assay. Exudates of three cyanobacterial species showed retinoid-like activity in the range of 269-2,265 ng retinoid equivalents (REQ)/L, while there was no detectable activity in exudates of the investigated algal species. The exudates of one green alga (Desmodesmus quadricaudus) and the two cyanobacterial species with greatest REQ levels, Microcystis aeruginosa and Cylindrospermopsis raciborskii, were selected for testing of the potential relation of retinoid-like activity to developmental toxicity in zebrafish embryos. The exudates of both cyanobacteria were indeed provoking diverse teratogenic effects (e.g. tail, spine and mouth deformation) and interference with growth in zebrafish embryos, while such effects were not observed for the alga. Fish embryos were also exposed to all-trans retinoic acid (ATRA) in a range equivalent to the REQ concentrations detected in exudates by in vitro bioassays. Both the phenotypes and effective concentrations of exudates corresponded to ATRA equivalents, supporting the hypothesis that the teratogenic effects of cyanobacterial exudates are likely to be associated with retinoid-like activity. The study documents that some cyanobacteria are able to produce and release retinoid-like compounds into the environment at concentrations equivalent to those causing teratogenicity in zebrafish. Hence, the characterization of retinoid-like and teratogenic potency should be included in the assessment of the potential adverse effects caused by the release of toxic and bioactive compounds during cyanobacterial blooms. PMID:25103898

Jonas, Adam; Buranova, Veronika; Scholz, Stefan; Fetter, Eva; Novakova, Katerina; Kohoutek, Jiri; Hilscherova, Klara

2014-10-01

152

METAL TOXICITY TO EMBRYOS AND LARVAE OF EIGHT SPECIES OF FRESHWATER FISH--II: COPPER  

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...

153

Decomposition and nutrient dynamics of litter from four species of freshwater emergent macrophytes  

Microsoft Academic Search

Nitrogen and phosphorus concentrations and mass remaining were followed for 30 months in decomposing litter of the perennial macrophytes Typha latifolia L., Carex lacustris Willd., Calamagrostis canadensis (Michx.) Nutt., and the annual Zizania aquatica L. in a fresh water tidal marsh in Massachusetts. Step-wise decreases in the mass remaining that corresponded to seasonal temperature changes were observed for all species.

James T. Morris; Kate Lajtha

1986-01-01

154

EFFECTS OF COPPER, NICKEL AND ZINC ON THREE SPECIES OF OREGON FRESHWATER SNAILS  

EPA Science Inventory

Three snail species collected from western Oregon were exposed to metals - Juga plicifera and Lithoglyphus virens, which inhabit cool coastal streams, and Physa gyrina, which is found in Willamette Valley ponds. J. plicifera were exposed in flow-through laboratory tests to copper...

155

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

2011-01-01

156

Conserved transcriptional responses to cyanobacterial stressors are mediated by alternate regulation of paralogous genes in Daphnia.  

PubMed

Despite a significant increase in genomic data, our knowledge of gene functions and their transcriptional responses to environmental stimuli remains limited. Here, we use the model keystone species Daphnia pulex to study environmental responses of genes in the context of their gene family history to better understand the relationship between genome structure and gene function in response to environmental stimuli. Daphnia were exposed to five different treatments, each consisting of a diet supplemented with one of five cyanobacterial species, and a control treatment consisting of a diet of only green algae. Differential gene expression profiles of Daphnia exposed to each of these five cyanobacterial species showed that genes with known functions are more likely to be shared by different expression profiles, whereas genes specific to the lineage of Daphnia are more likely to be unique to a given expression profile. Furthermore, while only a small number of nonlineage-specific genes were conserved across treatment type, there was a high degree of overlap in expression profiles at the functional level. The conservation of functional responses across the different cyanobacterial treatments can be attributed to the treatment-specific expression of different paralogous genes within the same gene family. Comparison with available gene expression data in the literature suggests differences in nutritional composition in diets with cyanobacterial species compared to diets of green algae as a primary driver for cyanobacterial effects on Daphnia. We conclude that conserved functional responses in Daphnia across different cyanobacterial treatments are mediated through alternate regulation of paralogous gene families. PMID:25754071

Asselman, Jana; Pfrender, Michael E; Lopez, Jacqueline A; De Coninck, Dieter I M; Janssen, Colin R; Shaw, Joseph R; De Schamphelaere, Karel A C

2015-04-01

157

Extinction Rates of North American Freshwater Fauna  

Microsoft Academic Search

Since 1900, 123 freshwater animal species have been recorded as extinct in North America. Hun- dreds of additional species of fishes, mollusks, crayfishes, and amphibians are considered imperiled. Using an exponential decay model, we derived recent and future extinction rates for North American freshwater fauna that are five times higher than those for terrestrial fauna. Assuming that imperiled freshwater species

Anthony Ricciardi; Joseph B. Rasmussen

1999-01-01

158

Arsenic concentration and speciation in five freshwater fish species from Back Bay near Yellowknife, NT, CANADA.  

PubMed

The concentration of total arsenic and five different arsenic species [As(III), As(V), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and arsenobetaine (AsB)], were measured in the muscle, liver and gastrointestinal tract (GIT) of five different fish species [lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum), northern pike (Esox lucius), white sucker (Catostomus commersoni) and longnose sucker (Catostomus catostomus)] from Back Bay, Great Slave Lake, near the city of Yellowknife, NT, Canada. The total concentration (dry weight) of arsenic in muscle ranged from 0.57 to 1.15 mg/kg, in the liver from 0.42 to 2.52 mg/kg and in the GIT from 1.48 to 8.92 mg/kg. Among fish species, C. commersoni had significantly higher total arsenic concentrations in the GIT than S. vitreum, E. lucius and C. clupeaformis, and higher total arsenic concentrations in the liver than C. clupeaformis. The mean concentration of As(III) and As(V) in the muscle of all fish ranged from < or =0.01 to 0.05 mg/kg and < or =0.01 to 0.02 mg/kg, respectively, and together comprised < or =7.5% of the total arsenic measured in muscle. The concentrations of MMA were below detection in the muscle of all five fish species. However, AsB and DMA were measured in all fish species and nearly all fish tissues. The concentrations of AsB ranged from 0.01 to 0.13 mg/kg and the concentrations of DMA ranged from <0.02 to 0.45 mg/kg. The majority (>50%) of organic arsenic in almost all of the tissues from fish caught in Back Bay was not directly identified. Evidence from the literature suggests that most of these other organic arsenic species were likely trimethylated arsenic compounds, however, further analytical work would need to be performed to verify this hypothesis. PMID:18214701

de Rosemond, Simone; Xie, Qianli; Liber, Karsten

2008-12-01

159

Levels, Distribution, and Health Risks of Polycyclic Aromatic Hydrocarbons in Four Freshwater Edible Fish Species from the Beijing Market  

PubMed Central

We first estimated the content of polycyclic aromatic hydrocarbons (PAHs) in the brain, liver, bladder, roe, and muscle of four species of edible freshwater fish from the Beijing market. The distribution characteristics of PAHs in these tissues and organs were analyzed to determine their health risks to humans. The results showed that the residual levels of wet weight and lipid-normalized weight ?PAHs in various tissues of these fish ranged from 0.51?ng·g?1 to 28.78?ng·g?1 and from 93.62?ng·g?1 to 8203.43?ng·g?1, respectively. The wet weight contents of ?PAHs were relatively higher in the brain and lower in the liver and muscle. But the differences were not significant. And the differences of lipid-normalized weight PAHs were significant, which in the bighead carp were found significantly the highest, followed in crucian carp, and the lowest in grass carp and carp. The contents of ?PAHs were the highest in the liver and the lowest in the brain. In the tissues with a higher lipid content, higher residual levels of PAHs were found. The carcinogenic risks for humans from residual ?PAHs in the various fish tissues were far below 10?5. PMID:23365511

Wu, Wen-Jing; Qin, Ning; He, Wei; He, Qi-Shuang; Ouyang, Hui-Ling; Xu, Fu-Liu

2012-01-01

160

Flow-plant interactions in open-channel flows: A comparative analysis of five freshwater plant species  

NASA Astrophysics Data System (ADS)

The paper reports a laboratory study of drag forces exerted on aquatic vegetation and their coupling with flow turbulence. The experiments were conducted in a 12.5 m long and 0.30 m wide flume, using five different freshwater plant species (Ranunculus penicillatus, Fontinalis antipyretica, Myriophyllum alterniflorum, Glyceria fluitans, and Callitriche stagnalis). Velocity components and drag forces were measured using two acoustic Doppler velocimeters (ADV) and a specially designed drag measurement device. Drag fluctuations exerted on the plants appeared to be closely related to the ambient turbulence, especially to large-scale turbulent structures. The enhanced turbulent energy downstream from the plants was associated with wake generation, with its magnitude controlled by plant morphology reconfiguration. Frequency spectra of drag fluctuations reveal a frequency range where they follow a power law that can be parameterized using plant and flow properties. The rescaled spectral functions are shown to match the collected data reasonably well. In addition, drag-velocity cross-correlation analyses enabled the estimation of the location of the resultant drag force, which can be interpreted as an integral measure of plant adaptation to the flow. The results revealed different degrees of adaptation of the plants to flowing water, withFontinalis and Glyceria showing the best hydrodynamic performances, i.e., lower levels of turbulence and drag generation.

Siniscalchi, Fabio; Nikora, Vladimir I.

2012-05-01

161

Pomphorhynchidae and quadrigyridae (Acanthocephala), including a new genus and species (Pallisentinae), from freshwater fishes, Cobitidae and Cyprinodontidae, in Turkey.  

PubMed

During a survey of freshwater fishes from Turkey two species of Acanthocephala, one of them new, were found. Pomphorhynchus tereticollis (Pomphorhynchidae) is reported at 24% prevalence in 37 Cobitis bilseli (Cobitidae) from Lake Beysehir, Konya, for the first time. The eoacanthoacaphalan Triaspiron aphanii gen. n. et sp. n. (Quadrigyridae), at a prevalence of 90%, is described from 29 Aphanius mento (Cyprinodontidae), from Kirkgöz Springs, Antalya. The new genus most closely resembles Raosentis Datta, 1947, both having a small spindle shaped trunk, and Acanthogyrus Thapar, 1927, both having a proboscis armature of three circles of hooks. Triaspiron differs from Raosentis in proboscis shape, cylindrical not globular, proboscis armature, three circles, a total of 16 hooks in all, not four circles, a total of 26-30 hooks in all, and trunk spination, two fields of spines in the anterior field with spines arranged in up to 40 circular rows, not a single field with 9-17 rows of spines. Triaspiron differs from Acanthogyrus in having fewer proboscis hooks, 16 compared with 18-24, arranged in three circles, one anterior and two posteriorly placed, with an unarmed region between, not three circles of hooks evenly spaced, and two fields of trunk spines, not one. PMID:23136795

Smales, Lesley R; Aydogdu, Ali; Emre, Yilmaz

2012-09-01

162

Erection of Ceratonova n. gen. (Myxosporea: Ceratomyxidae) to encompass freshwater species C. gasterostea n. sp. from threespine stickleback (Gasterosteus aculeatus) and C. shasta n. comb. from salmonid fishes.  

PubMed

Ceratonova gasterostea n. gen. n. sp. is described from the intestine of freshwater Gasterosteus aculeatus L. from the Klamath River, California. Myxospores are arcuate, 22.4 ± 2.6 ?m thick, 5.2 ± 0.4 ?m long, posterior angle 45° ± 24°, with 2 sub-spherical polar capsules, diameter 2.3 ± 0.2 ?m, which lie adjacent to the suture. Its ribosomal small subunit sequence was most similar to an intestinal parasite of salmonid fishes, Ceratomyxa shasta (97%, 1,671/1,692 nucleotides), and distinct from all other Ceratomyxa species (<85%), which are typically coelozoic parasites in the gall bladder or urinary system of marine fishes. We propose erection of genus Ceratonova to contain both intestinal, freshwater species and reassign the salmonid parasite as Ceratonova shasta n. comb. PMID:24754344

Atkinson, S D; Foott, J S; Bartholomew, J L

2014-10-01

163

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. PMID:18275608

2008-01-01

164

First evidence of “paralytic shellfish toxins” and cylindrospermopsin in a Mexican freshwater system, Lago Catemaco, and apparent bioaccumulation of the toxins in “tegogolo” snails ( Pomacea patula catemacensis)  

Microsoft Academic Search

Exposure to cyanobacterial toxins in freshwater systems, including both direct (e.g., drinking water) and indirect (e.g., bioaccumulation in food webs) routes, is emerging as a potentially significant threat to human health. We investigated cyanobacterial toxins, specifically cylindrospermopsin (CYN), the microcystins (MCYST) and the “paralytic shellfish toxins” (PST), in Lago Catemaco (Veracruz, Mexico). Lago Catemaco is a tropical lake dominated by

John P. Berry; Owen Lind

2010-01-01

165

Effects of habitat alteration caused by petrochemical activities and oil spills on the habitat use and interspecific relationships among four species of Afrotropical freshwater turtles  

Microsoft Academic Search

The large-scale effects of habitat alteration produced by oil-industry related pollution on the habitat use of four species\\u000a of freshwater turtles (Pelusios castaneus, Pelusios niger, Pelomedusa subrufa, Trionyx triunguis) were studied in the River Niger Delta, southern Nigeria (West Africa) between 1996 and 2004. The numbers of turtle specimens\\u000a observed during our study declined drastically in polluted sites, despite a

Luca Luiselli; Godfrey C. Akani; Edoardo Politano

166

Effects of habitat alteration caused by petrochemical activities and oil spills on the habitat use and interspecific relationships among four species of Afrotropical freshwater turtles  

Microsoft Academic Search

The large-scale effects of habitat alteration produced by oil-industry related pollution on the habitat use of four species\\u000a of freshwater turtles (Pelusios castaneus, Pelusios niger, Pelomedusa subrufa, Trionyx triunguis) were studied in the River Niger Delta, southern Nigeria (West Africa) between 1996 and 2004. The numbers of turtle specimens\\u000a observed during our study declined drastically in polluted sites, despite a

Luca Luiselli; Godfrey C. Akani; Edoardo Politano

2006-01-01

167

RNA-seq analysis reveals extensive transcriptional plasticity to temperature stress in a freshwater fish species  

PubMed Central

Background Identifying genes of adaptive significance in a changing environment is a major focus of ecological genomics. Such efforts were restricted, until recently, to researchers studying a small group of model organisms or closely related taxa. With the advent of next generation sequencing (NGS), genomes and transcriptomes of virtually any species are now available for studies of adaptive evolution. We experimentally manipulated temperature conditions for two groups of crimson spotted rainbowfish (Melanotaenia duboulayi) and measured differences in RNA transcription between them. This non-migratory species is found across a latitudinal thermal gradient in eastern Australia and is predicted to be negatively impacted by ongoing environmental and climatic change. Results Using next generation RNA-seq technologies on an Illumina HiSeq2000 platform, we assembled a de novo transcriptome and tested for differential expression across the treatment groups. Quality of the assembly was high with a N50 length of 1856 bases. Of the 107,749 assembled contigs, we identified 4251 that were differentially expressed according to a consensus of four different mapping and significance testing approaches. Once duplicate isoforms were removed, we were able to annotate 614 up-regulated transfrags and 349 that showed reduced expression in the higher temperature group. Conclusions Annotated blast matches reveal that differentially expressed genes correspond to critical metabolic pathways previously shown to be important for temperature tolerance in other fish species. Our results indicate that rainbowfish exhibit predictable plastic regulatory responses to temperature stress and the genes we identified provide excellent candidates for further investigations of population adaptation to increasing temperatures. PMID:23738713

2013-01-01

168

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

PubMed

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

2012-01-01

169

A new cucullanid species (Nematoda) from the freshwater fish Vieja intermedia (Günther, 1862) (Cichlidae) in Mexico.  

PubMed

A new nematode species, Cucullanus angeli n. sp., is described from specimens recovered from the intestine of Vieja intermedia (Günther, 1862) from the Lacantun River, State of Chiapas, Mexico. It is characterized largely by having an unusual distinct unpaired median papilla present on anterior cloacal lip in the male and the situation of phasmids (close to eighth pair of papillae); it is further characterized by equal spicules (length 175-475 microm), distribution of caudal papillae, a preanal sucker surrounded by first and second pair of papillae, and conical tail in both sexes, ending in small terminal digitiform process (being more conspicuous in the female). PMID:17626358

Cabañas-Carranza, Guillermina; Caspeta-Mandujano, Juan Manuel

2007-06-01

170

Diversity in leaf anatomy, and stomatal distribution and conductance, between salt marsh and freshwater species in the C(4) genus Spartina (Poaceae).  

PubMed

Leaf anatomy, stomatal density, and leaf conductance were studied in 10 species of Spartina (Poaceae) from low versus high salt marsh, and freshwater habitats. Internal structure, external morphology, cuticle structure, and stomatal densities were studied with light and electron microscopy. Functional significance of leaf structure was examined by measures of CO(2) uptake and stomatal distributions. All species have Kranz anatomy and C(4)delta(13)C values. Freshwater species have thin leaves with small ridges on adaxial sides and stomata on both adaxial and abaxial sides. By contrast, salt marsh species have thick leaves with very pronounced ridges on the adaxial side and stomata located almost exclusively on adaxial leaf surfaces. Salt marsh species also have a thicker cuticle on the abaxial than on the adaxial side of leaves, and CO(2) uptake during photosynthesis is restricted to the adaxial leaf surface. Salt marsh species are adapted to controlling water loss by having stomata in leaf furrows on the adaxial side, which increases the boundary layer, and by having large leaf ridges that fit together as the leaf rolls during water stress. Differences in structural-functional features of photosynthesis in Spartina species are suggested to be related to adaptations to saline environments. PMID:19522838

Maricle, Brian R; Koteyeva, Nuria K; Voznesenskaya, Elena V; Thomasson, Joseph R; Edwards, Gerald E

2009-01-01

171

A new cryptic species of South American freshwater pufferfish of the genus Colomesus (Tetraodontidae), based on both morphology and DNA data.  

PubMed

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

2013-01-01

172

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. PMID:24040239

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

2013-01-01

173

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

PubMed

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

2008-01-01

174

Lack of surface-associated microorganisms in a mixed species community of freshwater Unionidae  

USGS Publications Warehouse

To determine whether unionids contain surface-attached endosymbiotic bacteria, ciliates, or fungi, we used scanning electron microscopy to examine the epithelial surface of various organs within the digestive systems and mantle cavity of temperate river and lake unionids on a seasonal basis. We also cultured material removed from the lumen of these same organs and from the mantle cavity to detect cellobiose-, cellulose-, and chitin- degrading microbes. No true endosymbiotic fauna were observed attached to the surface of the digestive or mantle tissues of any species of unionid. Microbial growth on cellulose or chitin bacteriological media varied by season and habitat, but not by unionid species or source of the isolate. Lake unionids did not contain microbes capable of digesting cellulose or chitin, whereas unionids from the river site did in March and August, but not in December. Since these cultured cellulose- and chitin-degrading bacteria were never found attached to any unionid tissues, they appeared to be transient forms, not true endosymbionts. Microbes capable of digesting cellobiose were found in every unionid collected in all seasons and habitats, but again, no microbes were directly observed attached to unionid tissues. If unionids, like most other vertebrates, lack digestive enzymes required to initiate primary bond breakage, then the lack of cellulolytic and chitinolytic endosymbionts would affect the ability to utilize cellulose or chitin foods. Thus, in captivity dry feeds based on corn, soybeans, or nauplii should be pre-digested to ensure maximum absorption of nutrients by unionids. The lack of celluloytic or chitinolytic endosymbionts should not affect relocation success, though the seasonal role of transient microbes in unionid nutrition requires further investigation.

Nichols, S. Jerrine; Allen, J.; Walker, G.; Yokoyama, M.; Garling, D.

2001-01-01

175

Conversion of carotenoids into vitamins A1 and A2 in two species of freshwater fish  

PubMed Central

1. Examination of two zooplankton species predominating in fish ponds, Daphnia magna and Chironomus larvae, revealed the presence of ?- and ?-carotene, echinenone, canthaxanthin and 3-hydroxy-4-oxo-?-carotene in Daphnia, and ?-carotene and cryptoxanthin ester in Chironomus. No specific provitamins A2 (containing a 3,4-dehydro-?-ionone ring) were detected. 2. Guppies (Lebistes reticulatus) and platies (Xiphophorus variatus) were found to form vitamin A from ?-carotene and from its oxygen-containing derivatives isozeaxanthin, canthaxanthin and astaxanthin. Slight conversion into vitamin A2 seemed to occur simultaneously. 3,4-Dehydro-3?-hydroxy-?-carotene formed little vitamin A, and the latter was mainly of the A2 type. Lutein was devoid of provitamin A properties. 3. In addition to vitamin A, ?-carotene was detected in fish receiving the 4-oxo- and 4-hydroxy-carotenoids. A reaction scheme for the conversion of carotenoids into retinal and and 3,4-dehydroretinal is presented. 4. It is concluded that natural 4-oxo derivatives of ?-carotene may play a significant role as vitamin A precursors for fish. PMID:16742455

Gross, Jeana; Budowski, P.

1966-01-01

176

Conversion of carotenoids into vitamins A(1) and A(2) in two species of freshwater fish.  

PubMed

1. Examination of two zooplankton species predominating in fish ponds, Daphnia magna and Chironomus larvae, revealed the presence of alpha- and beta-carotene, echinenone, canthaxanthin and 3-hydroxy-4-oxo-beta-carotene in Daphnia, and beta-carotene and cryptoxanthin ester in Chironomus. No specific provitamins A(2) (containing a 3,4-dehydro-beta-ionone ring) were detected. 2. Guppies (Lebistes reticulatus) and platies (Xiphophorus variatus) were found to form vitamin A from beta-carotene and from its oxygen-containing derivatives isozeaxanthin, canthaxanthin and astaxanthin. Slight conversion into vitamin A(2) seemed to occur simultaneously. 3,4-Dehydro-3'-hydroxy-beta-carotene formed little vitamin A, and the latter was mainly of the A(2) type. Lutein was devoid of provitamin A properties. 3. In addition to vitamin A, beta-carotene was detected in fish receiving the 4-oxo- and 4-hydroxy-carotenoids. A reaction scheme for the conversion of carotenoids into retinal and and 3,4-dehydroretinal is presented. 4. It is concluded that natural 4-oxo derivatives of beta-carotene may play a significant role as vitamin A precursors for fish. PMID:16742455

Gross, J; Budowski, P

1966-12-01

177

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

PubMed

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

2012-06-01

178

Proteomic analysis of hepatic tissue of Cyprinus carpio L. exposed to cyanobacterial blooms in Lake Taihu, China.  

PubMed

With the rapid development of industry and agriculture and associated pollution, the cyanobacterial blooms in Lake Taihu have become a major threat to aquatic wildlife and human health. In this study, the ecotoxicological effects of cyanobacterial blooms on cage-cultured carp (Cyprinus carpio L.) in Meiliang Bay of Lake Taihu were investigated. Microcystins (MCs), major cyanobacterial toxins, have been detected in carp cultured at different experimental sites of Meiliang Bay. We observed that the accumulation of MCs in carp was closely associated with several environmental factors, including temperature, pH value, and density of cyanobacterial blooms. The proteomic profile of carp liver exposed to cyanobacterial blooms was analyzed using two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry. The toxic effects of cyanobacterial blooms on carp liver were similar to changes caused by MCs. MCs were transported into liver cells and induced the excessive production of reactive oxygen species (ROS). MCs and ROS inhibited protein phosphatase and aldehyde dehydrogenase (ALDH), directly or indirectly resulting in oxidative stress and disruption of the cytoskeleton. These effects further interfered with metabolic pathways in the liver through the regulation of series of related proteins. The results of this study indicated that cyanobacterial blooms pose a major threat to aquatic wildlife in Meiliang Bay in Lake Taihu. These results provided evidence of the molecular mechanisms underlying liver damage in carp exposed to cyanobacterial blooms. PMID:24558380

Jiang, Jinlin; Wang, Xiaorong; Shan, Zhengjun; Yang, Liuyan; Zhou, Junying; Bu, Yuanqin

2014-01-01

179

Proteomic Analysis of Hepatic Tissue of Cyprinus carpio L. Exposed to Cyanobacterial Blooms in Lake Taihu, China  

PubMed Central

With the rapid development of industry and agriculture and associated pollution, the cyanobacterial blooms in Lake Taihu have become a major threat to aquatic wildlife and human health. In this study, the ecotoxicological effects of cyanobacterial blooms on cage-cultured carp (Cyprinus carpio L.) in Meiliang Bay of Lake Taihu were investigated. Microcystins (MCs), major cyanobacterial toxins, have been detected in carp cultured at different experimental sites of Meiliang Bay. We observed that the accumulation of MCs in carp was closely associated with several environmental factors, including temperature, pH value, and density of cyanobacterial blooms. The proteomic profile of carp liver exposed to cyanobacterial blooms was analyzed using two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry. The toxic effects of cyanobacterial blooms on carp liver were similar to changes caused by MCs. MCs were transported into liver cells and induced the excessive production of reactive oxygen species (ROS). MCs and ROS inhibited protein phosphatase and aldehyde dehydrogenase (ALDH), directly or indirectly resulting in oxidative stress and disruption of the cytoskeleton. These effects further interfered with metabolic pathways in the liver through the regulation of series of related proteins. The results of this study indicated that cyanobacterial blooms pose a major threat to aquatic wildlife in Meiliang Bay in Lake Taihu. These results provided evidence of the molecular mechanisms underlying liver damage in carp exposed to cyanobacterial blooms. PMID:24558380

Jiang, Jinlin; Wang, Xiaorong; Shan, Zhengjun; Yang, Liuyan; Zhou, Junying; Bu, Yuanqin

2014-01-01

180

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.

2009-01-01

181

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)

182

Physiological interaction of Daphnia and Microcystis with regard to cyanobacterial secondary metabolites.  

PubMed

Cyanobacterial blooms in freshwater ecosystems are a matter of high concern with respect to human health and ecosystem services. Investigations on the role of cyanobacterial secondary metabolites have largely been confined to microcystins, although cyanobacteria produce a huge variety of toxic or inhibitory secondary metabolites. Mass occurrences of toxic cyanobacteria strongly impact freshwater zooplankton communities; especially the unselective filter feeder Daphnia. Daphnids have been shown to successfully suppress bloom formation. However, the opposite situation, i.e. the suppression of Daphnia populations by cyanobacteria can be observed as well. To understand these contradictory findings the elucidation of the underlying physiological mechanisms that help daphnids to cope with cyanotoxins is crucial. We fed Daphnia magna with the cyanobacterium Microcystis aeruginosa PCC7806 for 24h and used high-resolution LCMS analytics to analyze the Microcystis cells, the Daphnia tissue and the surrounding medium in order to investigate the fate of seven investigated cyanobacterial compounds (cyanopeptolins A-C, microcyclamide 7806A and aerucyclamides B-D). For none of these bioactive compounds evidence for biotransformation or biodegradation by Daphnia were found. Instead feeding and subsequent release experiments point at the importance of transport mechanisms in Daphnia with regard to the cyanopeptolins A and C and microcyclamide 7806A. In addition we found hints for new inducible defense mechanism in Microcystis against predation by Daphnia. These putative defense mechanisms include the elevated production of toxic compounds other than microcystins, as could be demonstrated here for aerucyclamide B and D, cyanopoeptolin B and microcyclamide 7806A. Moreover, our data demonstrate the elevated active export of at least one cyanobacterial compound (microcyclamide 7806A) into the surrounding medium as a response to grazer presence, which might constitute an entirely new not yet described cyanobacterial defense mechanism. PMID:25173836

Sadler, Thomas; von Elert, Eric

2014-11-01

183

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

PubMed Central

Abstract 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

2013-01-01

184

Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin.  

PubMed

This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11100 and from 20 to 248 mg As kg(-1) (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (>0.1% d.w.) in Cladophora sp. PMID:22981629

Pell, Albert; Márquez, Anna; López-Sánchez, José Fermín; Rubio, Roser; Barbero, Mercedes; Stegen, Susana; Queirolo, Fabrizio; Díaz-Palma, Paula

2013-01-01

185

Toxicity of nickel-spiked freshwater sediments to benthic invertebrates-Spiking methodology, species sensitivity, and nickel bioavailability  

USGS Publications Warehouse

This report summarizes data from studies of the toxicity and bioavailability of nickel in nickel-spiked freshwater sediments. The goal of these studies was to generate toxicity and chemistry data to support development of broadly applicable sediment quality guidelines for nickel. The studies were conducted as three tasks, which are presented here as three chapters: Task 1, Development of methods for preparation and toxicity testing of nickel-spiked freshwater sediments; Task 2, Sensitivity of benthic invertebrates to toxicity of nickel-spiked freshwater sediments; and Task 3, Effect of sediment characteristics on nickel bioavailability. Appendices with additional methodological details and raw chemistry and toxicity data for the three tasks are available online at http://pubs.usgs.gov/sir/2011/5225/downloads/.

Besser, John M.; Brumbaugh, William G.; Kemble, Nile E.; Ivey, Chris D.; Kunz, James L.; Ingersoll, Christopher G.; Rudel, David

2011-01-01

186

The Role of Nitrogen Fixation in Cyanobacterial Bloom Toxicity in a Temperate, Eutrophic Lake  

PubMed Central

Toxic cyanobacterial blooms threaten freshwaters worldwide but have proven difficult to predict because the mechanisms of bloom formation and toxin production are unknown, especially on weekly time scales. Water quality management continues to focus on aggregated metrics, such as chlorophyll and total nutrients, which may not be sufficient to explain complex community changes and functions such as toxin production. For example, nitrogen (N) speciation and cycling play an important role, on daily time scales, in shaping cyanobacterial communities because declining N has been shown to select for N fixers. In addition, subsequent N pulses from N2 fixation may stimulate and sustain toxic cyanobacterial growth. Herein, we describe how rapid early summer declines in N followed by bursts of N fixation have shaped cyanobacterial communities in a eutrophic lake (Lake Mendota, Wisconsin, USA), possibly driving toxic Microcystis blooms throughout the growing season. On weekly time scales in 2010 and 2011, we monitored the cyanobacterial community in a eutrophic lake using the phycocyanin intergenic spacer (PC-IGS) region to determine population dynamics. In parallel, we measured microcystin concentrations, N2 fixation rates, and potential environmental drivers that contribute to structuring the community. In both years, cyanobacterial community change was strongly correlated with dissolved inorganic nitrogen (DIN) concentrations, and Aphanizomenon and Microcystis alternated dominance throughout the pre-toxic, toxic, and post-toxic phases of the lake. Microcystin concentrations increased a few days after the first significant N2 fixation rates were observed. Then, following large early summer N2 fixation events, Microcystis increased and became most abundant. Maximum microcystin concentrations coincided with Microcystis dominance. In both years, DIN concentrations dropped again in late summer, and N2 fixation rates and Aphanizomenon abundance increased before the lake mixed in the fall. Estimated N inputs from N2 fixation were large enough to supplement, or even support, the toxic Microcystis blooms. PMID:23405255

Beversdorf, Lucas J.; Miller, Todd R.; McMahon, Katherine D.

2013-01-01

187

Cyanobacterial diversity in the phyllosphere of a mangrove forest.  

PubMed

The cyanobacterial community colonizing phyllosphere in a well-preserved Brazilian mangrove ecosystem was assessed using cultivation-independent molecular approaches. Leaves of trees that occupy this environment (Rhizophora mangle,Avicennia schaueriana and Laguncularia racemosa) were collected along a transect beginning at the margin of the bay and extending upland. The results demonstrated that the phyllosphere of R. mangle and L. racemosa harbor similar assemblages of cyanobacteria at each point along the transect. A. schaueriana, found only in the coastal portions of the transect, was colonized by assemblages with lower richness than the other trees. However, the results indicated that spatial location was a stronger driver of cyanobacterial community composition than plant species. Distinct cyanobacterial communities were observed at each location along the coast-to-upland transect. Clone library analysis allowed identification of 19 genera of cyanobacteria and demonstrated the presence of several uncultivated taxa. A predominance of sequences affiliated with the orders Nostocales and Oscillatoriales was observed, with a remarkable number of sequences similar to genera Symphyonemopsis/Brasilonema (order Nostocales). The results demonstrated that phyllosphere cyanobacteria in this mangrove forest ecosystem are influenced by environmental conditions as the primary driver at the ecosystem scale, with tree species exerting some effect on community structure at the local scale. PMID:22611551

Rigonato, Janaina; Alvarenga, Danillo Oliveira; Andreote, Fernando Dini; Dias, Armando Cavalcante Franco; Melo, Itamar Soares; Kent, Angela; Fiore, Marli Fátima

2012-05-01

188

Genetic diversity in cyanobacterial symbionts of thalloid bryophytes.  

PubMed

Two species of thalloid liverworts, Blasia pusilla and Cavicularia densa, form stable symbioses with nitrogen-fixing cyanobacteria. Both bryophytes promote the persistence of their cyanobacterial associations by producing specialized gemmae, which facilitate the simultaneous dispersal of the host and its nitrogen-fixing symbionts. Here the genetic diversity of cyanobacterial symbionts of Blasia and Cavicularia is examined. The results indicate that the primary symbionts of both bryophytes are closely related and belong to a specific group of symbiotic Nostoc strains. Related strains have previously been reported from hornworts and cycads, and from many terricolous cyanolichens. The evolutionary origins of all these symbioses may trace back to pre-Permian times. While the laboratory strain Nostoc punctiforme PCC 73102 has been widely used in experimental studies of bryophyte-Nostoc associations, sequence-identical cyanobionts have not yet been identified from thalloid liverworts in the field. PMID:18325923

Rikkinen, Jouko; Virtanen, Viivi

2008-01-01

189

Species diversity of Plagiorchis Lühe, 1899 (Digenea: Plagiorchiidae) in lymnaeid snails from freshwater ecosystems in central Europe revealed by molecules and morphology.  

PubMed

Larval stages of Plagiorchis spp. are both ubiquitous and ecologically important parasites in snail populations of freshwater ecosystems in Europe. However, difficulties in distinguishing the morphologically similar cercariae used for species identification, may lead to underestimation of species diversity. In this study, 38 isolates of Plagiorchis spp. infecting two lymnaeid snails, Lymnaea stagnalis (L.) and Radix auricularia (L.), in five central European freshwater ecosystems were subjected to morphological and molecular assessment. Five morphologically homogeneous and genetically distinct lineages of Plagiorchis spp. were identified via matching molecular data for the mitochondrial cytochrome c oxidase subunit I (cox1) gene with detailed morphological and morphometric data of the cercariae. Comparative sequence analysis using partial 28S rDNA and ITS1-5.8S-ITS2 sequences revealed that three distinct cox1 lineages are conspecific with Plagiorchis elegans (Rudolphi, 1802), P. maculosus (Rudolphi, 1802) and P. koreanus Ogata, 1938, respectively, whereas the lineage identified based on cercarial morphology as P. neomidis Brendow, 1970 plus a single isolate that could not be assigned to a described species, did not match any of the available sequences for Plagiorchis spp. A key to the cercariae of Plagiorchis spp. parasitising lymnaeid populations in central Europe is provided to facilitate identification. PMID:24711111

Zikmundová, Jana; Georgieva, Simona; Faltýnková, Anna; Soldánová, Miroslava; Kostadinova, Aneta

2014-05-01

190

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.

2011-01-31

191

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

PubMed

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

2011-11-15

192

A pair of chiral flavonolignans as novel anti-cyanobacterial allelochemicals derived from barley straw (Hordeum vulgare): characterization and comparison of their anti-cyanobacterial activities.  

PubMed

The inhibitory effect of barley straw (Hordeum vulgare) on cyanobacteria has been observed in many field and laboratory studies for over 30 years, although the compounds responsible for this anti-cyanobacterial effect have remained unknown. In this study, a pair of chiral flavonolignans were isolated from barley straw extract using a bioassay-guided isolation procedure against Microcystis sp. The structures of the allelopathic compounds were elucidated by NMR (nuclear magnetic resonance) and HPLC-MS (high performance liquid chromatography-mass spectrometry), and turned out to be salcolin A and B. The enantiomers differ in their anti-cyanobacterial abilities. Both enantiomers exhibited inhibitory effects on Microcystis sp., and the EC50 (concentration for 50% of maximal effect) of salcolin A and B were 6.02?×?10(-5) and 9.60?×?10(-5?) mol?l(-1) , respectively. Furthermore, the modes of actions of the enantiomers were investigated and compared at a single cell level by flow cytometry. Salcolin A was found to induce an increase on cyanobacterial intracellular ROS (reactive oxygen species) levels and to inhibit esterase activity, whereas salcolin B caused leakages of cyanobacterial cytoplasms. Thus, salcolin A was more 'algistatic', and salcolin B was more 'algicidal'. This study suggests that salcolin is the key allelochemical in barley straw's inhibitory effect on cyanobacteria and could be used as an agent in the future control of cyanobacterial harmful algae blooms. PMID:24034604

Xiao, Xi; Huang, Haomin; Ge, Zhiwei; Rounge, Trine B; Shi, Jiyan; Xu, Xinhua; Li, Ruobing; Chen, Yingxu

2014-05-01

193

The structural code of cyanobacterial genomes  

PubMed Central

A periodic bias in nucleotide frequency with a period of about 11 bp is characteristic for bacterial genomes. This signal is commonly interpreted to relate to the helical pitch of negatively supercoiled DNA. Functions in supercoiling-dependent RNA transcription or as a ‘structural code’ for DNA packaging have been suggested. Cyanobacterial genomes showed especially strong periodic signals and, on the other hand, DNA supercoiling and supercoiling-dependent transcription are highly dynamic and underlie circadian rhythms of these phototrophic bacteria. Focusing on this phylum and dinucleotides, we find that a minimal motif of AT-tracts (AT2) yields the strongest signal. Strong genome-wide periodicity is ancestral to a clade of unicellular and polyploid species but lost upon morphological transitions into two baeocyte-forming and a symbiotic species. The signal is intermediate in heterocystous species and weak in monoploid picocyanobacteria. A pronounced ‘structural code’ may support efficient nucleoid condensation and segregation in polyploid cells. The major source of the AT2 signal are protein-coding regions, where it is encoded preferentially in the first and third codon positions. The signal shows only few relations to supercoiling-dependent and diurnal RNA transcription in Synechocystis sp. PCC 6803. Strong and specific signals in two distinct transposons suggest roles in transposase transcription and transpososome formation. PMID:25056315

Lehmann, Robert; Machné, Rainer; Herzel, Hanspeter

2014-01-01

194

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. PMID:23840163

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

2013-01-01

195

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

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. PMID:23840163

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

2013-01-01

196

Detection of Neorickettsia risticii from various freshwater snail species collected from a district irrigation canal in Nevada County, California.  

PubMed

This study investigated the role of a district irrigation canal in Nevada County, California, USA, as the point source of infection for Neorickettsia risticii, causative agent of equine neorickettsiosis (EN). A total of 568 freshwater snails comprising Juga spp., Planorbella subcrenata (Carpenter, 1857) (Rough Rams-horn), Physella virgata (Gould, 1855) (Protean Physa) and feces from three horses with EN were collected and tested for N. risticii by real-time PCR. A total of four freshwater snails tested PCR positive for N. risticii. Phylogenetic analysis showed 99.8-100% homology between the different snail and horse N. risticii isolates. This study represents the first report of infection with N. risticii in Planorbella subcrenata and suggests that the irrigation canal was the aquatic environment responsible for the spread of N. risticii. PMID:23566936

Pusterla, Nicola; Hagerty, Daniel; Mapes, Samantha; Vangeem, Josh; Groves, Lindsey T; Dinucci, Mario; Fielding, Langdon C; Higgins, Jill C

2013-08-01

197

Cyanobacterial Oxygenic Photosynthesis is Protected by Flavodiiron Proteins.  

PubMed

Flavodiiron proteins (FDPs, also called flavoproteins, Flvs) are modular enzymes widely present in Bacteria and Archaea. The evolution of cyanobacteria and oxygenic photosynthesis occurred in concert with the modulation of typical bacterial FDPs. Present cyanobacterial FDPs are composed of three domains, the ?-lactamase-like, flavodoxin-like and flavin-reductase like domains. Cyanobacterial FDPs function as hetero- and homodimers and are involved in the regulation of photosynthetic electron transport. Whilst Flv2 and Flv4 proteins are limited to specific cyanobacterial species (?-cyanobacteria) and function in photoprotection of Photosystem II, Flv1 and Flv3 proteins, functioning in the "Mehler-like" reaction and safeguarding Photosystem I under fluctuating light conditions, occur in nearly all cyanobacteria and additionally in green algae, mosses and lycophytes. Filamentous cyanobacteria have additional FDPs in heterocyst cells, ensuring a microaerobic environment for the function of the nitrogenase enzyme under the light. Here, the evolution, occurrence and functional mechanisms of various FDPs in oxygenic photosynthetic organisms are discussed. PMID:25761262

Allahverdiyeva, Yagut; Isojärvi, Janne; Zhang, Pengpeng; Aro, Eva-Mari

2015-01-01

198

Artificially accelerating the reversal of desertification: cyanobacterial inoculation facilitates the succession of vegetation communities.  

PubMed

Desertification has been recognized as a global environmental problem, and one region experiencing ongoing desertification is the eastern edge of Qubqi Desert (Inner Mongolia). To investigate the facilitating effects of cyanobacterial inoculation technology on the desertification control along this steppe-desert transition region, artificial cyanobacterial crusts were constructed with two filamentous cyanobacteria 3 and 8 years ago combined with Salix planting. The results showed that no crusts formed after 3 years of fixation only with Salix planting, whereas after cyanobacterial inoculation, the crusts formed quickly and gradually succeed to moss crusts. During that course, topsoil environments were gradually improved, providing the necessary material basis for the regeneration of vascular plants. In this investigation, total 27 species of vascular plants had regenerated in the experimental region, mainly belonging to Asteraceae, Poaceae, Chenopodiaceae and Leguminosae. Using space time substitution, the dominant species along with the application of cyanobacterial inoculation technology succeeded from Agriophyllum squarrosum ultimately to Leymus chinensis. In addition, it was found that the shady side of the dunes is more conducive to crust development and succession of vegetation communities. Conclusively, our results indicate artificial cyanobacterial inoculation technology is an effective and desirable path for desertification control. PMID:24303976

Lan, Shubin; Zhang, Qingyi; Wu, Li; Liu, Yongding; Zhang, Delu; Hu, Chunxiang

2014-01-01

199

Influence of species and sex on metal residues in freshwater mussels (Family Unionidae) from the St. Lawrence River, with implications for biomonitoring programs  

SciTech Connect

The implementation of freshwater mussel watch programs has been hindered by a lack of information on biological factors affecting the levels of contaminants accumulated by these organisms. This study investigated the influence of species and sex on metal residues in Elliptio complanata and Lampsilis radiata radiata (Family Unionidae) from the St. Lawrence River. Mussels were collected from sites representing a wide range of types and degrees of metal pollution. Composite samples of five specimens (males and females combined) per species per site and five specimens per sex per species per site were analyzed for residues of 12 metals in the soft tissues to determine the effects of species and sex, respectively, on variability in the data. Interspecific differences in bioaccumulation were observed for most metals; however, concentrations were frequently correlated between species and the differences could therefore be quantified. Elliptio complanata demonstrated a broader response range to the same exposures than Lampsilis radiata radiata for most metals, suggesting that it may be more sensitive to changes in pollution status. Differences in metal uptake between the sexes were less pronounced than differences between species, and male specimens displayed less variability than females. Consideration of these factors in mussel biomonitoring programs should greatly improve sensitivity and precision.

Metcalfe-Smith, J.L. (Environment Canada, Burlington, Ontario (Canada). Rivers Research Branch)

1994-09-01

200

Oligopeptides as Biomarkers of Cyanobacterial Subpopulations. Toward an Understanding of Their Biological Role  

PubMed Central

Cyanobacterial oligopeptides comprise a wide range of bioactive and/or toxic compounds. While current research is strongly focused on exploring new oligopeptide variants and their bioactive properties, the biological role of these compounds remains elusive. Oligopeptides production abilities show a remarkably patchy distribution among conspecific strains. This observation has prompted alternative approaches to unveil their adaptive value, based on the use of cellular oligopeptide compositions as biomarkers of intraspecific subpopulations or chemotypes in freshwater cyanobacteria. Studies addressing the diversity, distribution, and dynamics of chemotypes in natural systems have provided important insights into the structure and ecology of cyanobacterial populations and the adaptive value of oligopeptides. This review presents an overview of the fundamentals of this emerging approach and its most relevant findings, and discusses our current understanding of the role of oligopeptides in the ecology of cyanobacteria. PMID:24960202

Agha, Ramsy; Quesada, Antonio

2014-01-01

201

Freshwater Blooms  

NSDL National Science Digital Library

This Bigelow Laboratory "Special Topics" page discusses freshwater harmful algal blooms (HABs). The interactive web page describes the features of a freshwater HAB with a focus on location, organisms affected, human symptoms, toxins (neurotoxins and hepatotoxins), and causative organisms. Links are provided to other pages within the Toxic and Harmful Algal Blooms collection.

Bigelow Laboratory for Ocean Sciences

202

Acute, chronic and reproductive toxicity of complex cyanobacterial blooms in Daphnia magna and the role of microcystins.  

PubMed

Toxic cyanobacterial blooms are a global threat to human health and aquatic biota. While the ecotoxicity of cyanobacterial toxins such as microcystins has been studied extensively, little is known about the risks they pose in the wild, i.e. within complex biomasses. In this work, crustaceans (Daphnia magna) were exposed to varying concentrations (0-405 mg d.w L(-1)) of eight complex cyanobacterial water bloom samples in a series of acute (48 h) and chronic (21 day) toxicity experiments. Further acute and chronic exposure assays were performed using aqueous extracts of the crude biomass samples and two fractions prepared by solid phase extraction (SPE) of the aqueous extracts. The cyanobacterial biomasses differed with respect to their dominant cyanobacterial species and microcystin contents. High acute toxicity was observed for 6 of the 8 crude biomass samples. Chronic exposure assays were performed using one complex biomass sample and its various subsamples/fractions. The complex biomass, the crude aqueous extract, and the microcystin-free SPE permeate all elicited similar and significant lethal effects, with LC50 values of around 35.6 mg biomass d.w L(-1) after 21 days. The cyanobacterial biomass samples also affected reproductive health, significantly increasing the time to the first brood (LOEC = 45 mg d.w L(-1) exposure) and inhibiting fecundity by 50% at 15 mg d.w L(-1). Conversely, the microcystin-containing C18-SPE eluate fraction had only weak effects in the chronic assay. These results indicate that cyanobacterial water blooms are highly toxic to zooplankton (both acutely and chronically) at environmentally relevant concentrations. However, the effects observed in the acute and chronic assays were independent of the samples' microcystin contents. Our results thus point out the importance of other cyanobacterial components such as lipopolysaccharides, various peptides and depsipeptides, polar alkaloid metabolites or other unidentified metabolites in the overall ecotoxicity of complex cyanobacterial blooms. PMID:24412459

Smutná, Marie; Babica, Pavel; Jarque, Sergio; Hilscherová, Klára; Maršálek, Blahoslav; Haeba, Maher; Bláha, Ludek

2014-03-01

203

Comparison of Ba/Ca and ?OWATER18 as freshwater proxies: A multi-species core-top study on planktonic foraminifera from the vicinity of the Orinoco River mouth  

NASA Astrophysics Data System (ADS)

Past river run-off is an important measure for the continental hydrological cycle and the assessment of freshwater input into the ocean. However, paleosalinity reconstructions applying different proxies in parallel often show offsets between the respective methods. Here, we compare the established foraminiferal Ba/Ca and ?OWATER18 salinity proxies for their capability to record the highly seasonal Orinoco freshwater plume in the eastern Caribbean. For this purpose we obtained a data set comprising Ba/Ca and ?OWATER18 determined on multiple species of planktonic foraminifera from core tops distributed around the Orinoco River mouth. Our findings indicate that interpretations based on either proxy could lead to different conclusions. In particular, Ba/Ca and ?OWATER18 diverge in their spatial distribution due to different governing factors. Apparently, the Orinoco freshwater plume is best tracked by Ba/Ca ratios of G. ruber (pink and sensu lato morphotypes), while ?OWATER18 based on the same species is more related to the local precipitation-evaporation balance overprinting the riverine freshwater contribution. Other shallow dwelling species (G. sacculifer, O. universa) show a muted response to the freshwater discharge, most likely due to their ecological and habitat preferences. Extremely high Ba/Ca ratios recorded by G. ruber are attributed to Ba2+-desorption from suspended matter derived from the Orinoco. Samples taken most proximal to the freshwater source do not show pronounced Ba/Ca or ?OWATER18 anomalies. Here, the suspension loaded freshwater lid developing during maximum discharge suppresses foraminiferal populations. Both proxies are therefore biased towards dry season conditions at these sites, when surface salinity is only minimally reduced.

Bahr, André; Schönfeld, Joachim; Hoffmann, Julia; Voigt, Silke; Aurahs, Ralf; Kucera, Michal; Flögel, Sascha; Jentzen, Anna; Gerdes, Axel

2013-12-01

204

Siderophores: The special ingredient to cyanobacterial blooms  

NASA Astrophysics Data System (ADS)

Freshwater lakes provide a number of significant ecological services including clean drinking water, habitat for aquatic biota, and economic benefits. The provision of these ecological services, as well as the health of these aquatic systems, is threatened by the excessive growth of algae, specifically, cyanobacteria. Historically, blooms have been linked to eutrophication but recent occurrences indicate that there are less dramatic changes that induce these blooms. Iron is an essential micronutrient required for specific essential metabolic pathways; however, the amount of biologically available iron in naturally occurring lake ranges from saturation to much lower than cell transport affinities. To assist in the modulation of iron availabilities, cyanobacteria in culture produce low molecular weight compounds that function in an iron binding and acquisition system; nevertheless, this has yet to be confirmed in naturally occurring lakes. This project explored the relationship of P, N and in particular, Fe, in the promotion of cyanobacteria harmful algal blooms in 30 natural freshwater lakes located in and around the Elk Island National Park, Alberta. It is hypothesized that cyanobacteria produce and utilize iron chelators called siderophores in low Fe and nitrogen (N) conditions, creating a competitive advantage over other algae in freshwater lakes. Lakes were selected to represent a range of iron availability to explore the nutrient composition of lakes that propagated cyanobacteria harmful algal blooms (cHABs) compared to lakes that did not. Lake water was analyzed for nutrients, microbial composition, siderophore concentration, and toxin concentration. Modifications were made to optimize the Czaky and Arnow tests for hydroxamate- and catecholate-type siderophores, respectively, for field conditions. Preliminary results indicate the presence of iron-binding ligands (0.11-2.34 mg/L) in freshwater lakes characterized by widely ranging Fe regimes (0.04-2.74 mg/L). Furthermore, the concentration of iron-binding ligands was found to have a positive correlation to presence of cyanobacteria concentration, indicating a potential relationship between Fe, siderophores, and cyanobacteria. This project works to improve the understanding of freshwater cyanobacteria growth dynamics by investigating the physiological and biochemical processes leading to cHABs. The importance of this project lies in the understanding of elementary nutrient requirements in all algae and how cyanobacteria are able to access low concentration pools and subsequently bloom over other algal species. Investigating the nutrient regimes that stimulate siderophore production and the subsequent production of potentially toxic cyanobacteria blooms is important for lake management and preservation, specifically in the eutrophic and hypereutrophic freshwater lakes of Alberta.

Du, Xue; Creed, Irena; Trick, Charles

2013-04-01

205

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. PMID:21599918

2011-01-01

206

A Freshwater Classification Approach for Biodiversity Conservation Planning  

Microsoft Academic Search

Freshwater biodiversity is highly endangered and faces increasing threats worldwide. To be com- plete, regional plans that identify critical areas for conservation must capture representative components of freshwater biodiversity as well as rare and endangered species. We present a spatially hierarchical approach to classify freshwater systems to create a coarse filter to capture representative freshwater biodiversity in regional conservation plans.

JONATHAN V. HIGGINS; MARK T. BRYER; MARY L. KHOURY; THOMAS W. FITZHUGH

2005-01-01

207

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. PMID:19146659

Xu, Minli; Su, Zhengchang

2009-01-01

208

The Decline of Freshwater Ecosystems  

NSDL National Science Digital Library

This article discusses the risks that freshwater ecosystems face and how species nearby are affected by dams, dredging, and channelization of streams. It points out that even though freshwater ecosystems are limited in extent, covering about 1 percent of the Earth's surface, they are highly diverse and contain a disproportionally large number of the world's species. Statistics are given to illustrate the increase in waterways that have been altered for navigation. Some actions that are being taken to reduce threats to freshwater ecosystems are also mentioned.

1999-01-01

209

Cyanobacterial Blooms: Toxins, Tastes, and Odors  

E-print Network

;Hepatotoxins Neurotoxins Dermatoxins Taste/Odor CYL MC ANA SAX GEOS MIB Anabaena X X X X X X ? Aphanizomenon X courtesy of A. St. Amand Anabaena Aphanizomenon PlanktothrixMicrocystis Cyanobacterial Harmful Algal Blooms

US Army Corps of Engineers

210

Cyanobacterial Flora from Polluted Industrial Effluents  

Microsoft Academic Search

Effluents originating from pesticides, agro-chemicals, textile dyes and dyestuffs industries are always associated with high\\u000a turbidity, colour, nutrient load, and heavy metals, toxic and persistent compounds. But even with such an anthropogenic nature,\\u000a these effluents contain dynamic cyanobacterial communities. Documentation of cyanobacterial cultures along the water channels\\u000a of effluents discharged by above mentioned industries along the west coast of India

Amit Parikh; Vishal Shah; Datta Madamwar

2006-01-01

211

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. PMID:16563160

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

2006-01-01

212

Structure of cyanobacterial photosystem I.  

PubMed

Photosystem I is one of the most fascinating membrane protein complexes for which a structure has been determined. It functions as a bio-solar energy converter, catalyzing one of the first steps of oxygenic photosynthesis. It captures the light of the sun by means of a large antenna system, consisting of chlorophylls and carotenoids, and transfers the energy to the center of the complex, driving the transmembrane electron transfer from plastoquinone to ferredoxin. Cyanobacterial Photosystem I is a trimer consisting of 36 proteins to which 381 cofactors are non-covalently attached. This review discusses the complex function of Photosystem I based on the structure of the complex at 2.5 A resolution as well as spectroscopic and biochemical data. PMID:15977059

Grotjohann, Ingo; Fromme, Petra

2005-01-01

213

Appendages of the cyanobacterial cell.  

PubMed

Extracellular non-flagellar appendages, called pili or fimbriae, are widespread in gram-negative bacteria. They are involved in many different functions, including motility, adhesion, biofilm formation, and uptake of DNA. Sequencing data for a large number of cyanobacterial genomes revealed that most of them contain genes for pili synthesis. However, only for a very few cyanobacteria structure and function of these appendages have been analyzed. Here, we review the structure and function of type IV pili in Synechocystis sp. PCC 6803 and analyze the distribution of type IV pili associated genes in other cyanobacteria. Further, we discuss the role of the RNA-chaperone Hfq in pilus function and the presence of genes for the chaperone-usher pathway of pilus assembly in cyanobacteria. PMID:25749611

Schuergers, Nils; Wilde, Annegret

2015-01-01

214

Identifying freshwater mussels (Unionoida) and parasitic glochidia larvae from host fish gills: a molecular key to the North and Central European species.  

PubMed

Freshwater mussels (order Unionoida) represent one of the most severely endangered groups of animals due to habitat destruction, introduction of nonnative species, and loss of host fishes, which their larvae (glochidia) are obligate parasites on. Conservation efforts such as habitat restoration or restocking of host populations are currently hampered by difficulties in unionoid species identification by morphological means. Here we present the first complete molecular identification key for all seven indigenous North and Central European unionoid species and the nonnative Sinanodonta woodiana, facilitating quick, low-cost, and reliable identification of adult and larval specimens. Application of this restriction fragment length polymorphisms (RFLP) key resulted in 100% accurate assignment of 90 adult specimens from across the region by digestion of partial ITS-1 (where ITS is internal transcribed spacer) polymerase chain reaction (PCR) products in two to four single digestions with five restriction endonucleases. In addition, we provide protocols for quick and reliable extraction and amplification of larval mussel DNA from complete host fish gill arches. Our results indicate that this new method can be applied on infection rates as low as three glochidia per gill arch and enables, for the first time, comprehensive, large-scale assessments of the relative importance of different host species for given unionoid populations. PMID:22837823

Zieritz, Alexandra; Gum, Bernhard; Kuehn, Ralph; Geist, Juergen

2012-04-01

215

SECONDARY METABOLITES FROM PLANTS AND MARINE ORGANISMS AS SELECTIVE ANTI-CYANOBACTERIAL AGENTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Extracts of more than one thousand species of plants and marine organisms were evaluated for selective algicidal activity against the musty-odor cyanobacterium (blue-green alga) Oscillatoria perornata. Bioassay-guided fractionation yielded anti-cyanobacterial compounds from the tropical marine brow...

216

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

PubMed

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

2008-01-01

217

Cyanobacterial Blooms in the Wetlands of the Perth region, Taxonomy and Distribution: an overview  

Microsoft Academic Search

The distribution pattern (spatial and temporal) of cyanobacterial blooms in Perth wetlands and the Canning River in Western Australia has been investigated sporadically over a span of 20 years. The major bloom-forming species have been identified as Microcystis aeruginosa, M. flos-aquae, Anabaena circinalis, A. spiroides and Nodularia spumigena. Blooms of potentially toxic Anabaena spp. have occurred in the Canning River

J John; Annabeth Kemp

2006-01-01

218

Hepatotoxic cyanobacterial blooms in the lakes of northern Poland.  

PubMed

The lakes of northern Poland are among the recreational sites most valued by Polish and German holiday makers. Given the socioeconomic importance of these lakes, water quality should be maintained at high levels for such intensive recreational purposes. In 2002 studies of species composition, biomass, and toxin production by phytoplankton and the attendant physicochemical variables were performed in order to assess the risk of cyanobacterial blooms in selected northern lakes: Lakes Jeziorak, Jagodne, Szymoneckie, Szymon, Taltowisko, Siecino, and Trzesiecko. The research showed that total phosphorus (0.1 mg P/L) and total nitrogen (1.5 mg N/L) in the studied lakes almost exceeded the permissible limits for eutrophication of water bodies. Most phytoplankton samples were taken in late summer, when cyanobacteria were expected to reach their highest biomass. At the time of sampling most of the lakes were dominated by oscillatorialean and nostocalean species. Average chlorophyll-a concentration was higher than 10 microg/L in almost all the lakes studied, which corresponded with an average microcystin concentration in the range of 4-5 microg/L. The main microcystins in the analyzed samples were dmMC-RR, MC-RR, MC-YR, and MC-LR. The results demonstrated a potential for intensive cyanobacterial blooms to appear during the summer in northern Polish lakes. The levels of cyanobacteria found in the lakes investigated indicated that toxicity had reached the first-alert level according to World Health Organization recommendations. If microcystin-producing cyanobacteria dominate, with a microcystin concentration of 2-4 microg/L, symptoms of toxicity can appear in the swimmers most sensitive to exposure. Analysis of cyanobacterial assemblages in northern Polish lakes also indicated a significant presence of Aphanizomenon species including a Scandinavian species, A. skujae (Skuja) Kom.-Legn. & Cronb. Future investigations of Polish lakes also should assess neurotoxins and study the biology of their producers. This study was the first attempt to evaluate the potential danger of toxic cyanobacterial blooms in the lakes of northern Poland. PMID:16161103

Mankiewicz, Joanna; Komárková, Jarka; Izydorczyk, Katarzyna; Jurczak, Tomasz; Tarczynska, Ma?gorzata; Zalewski, Maciej

2005-10-01

219

Species-specific preferences of German recreational anglers for freshwater fishing experiences, with emphasis on the intrinsic utilities of fish stocking and wild fishes.  

PubMed

To answer the question, whether anglers have an intrinsic preference for stocking or a preference for catch outcomes (e.g. catch rates) believed to be maintained by stocking, a discrete choice experiment was conducted among a sample of anglers (n = 1335) in Lower Saxony, Germany. After controlling for catch aspects of the fishing experience, no significant influence of two stocking attributes (stocking frequency and composition of the catch in terms of wild v. hatchery fishes) on the utility gained from fishing was found for any of the freshwater species that were studied. It was concluded that the previously documented large appreciation of fish stocking by anglers may be indicative of an underlying preference for sufficiently high catches rather than reflect an intrinsic preference for stocking or the catching of wild fishes per se. PMID:25469949

Arlinghaus, R; Beardmore, B; Riepe, C; Meyerhoff, J; Pagel, T

2014-12-01

220

Heavy metal distribution in tissues of six fish species included in human diet, inhabiting freshwaters of the Nature Park "Hutovo Blato" (Bosnia and Herzegovina).  

PubMed

The aim of the study was to quantify heavy metal (mercury, lead, cadmium, and arsenic) concentration in tissues (muscles, liver, kidney, gills, and gonads) of six fish species (carp: Cyprinus carpio, tench: Tinca tinca, pumpkinseed: Lepomis gibosus, prussian carp: Carassius auratus gibelio, hasselquist: Salmo dentex, eel: Anguilla anguilla) from the freshwaters of the Nature Park Hutovo Blato, Bosnia and Herzegovina, and determine whether they are potentially harmful for human health if included in the diet. Fish were angled from the Svitava Lake in the second part of August of the year 2003, and fish tissues were stored at -18 degrees C until analysis. Heavy metal concentration was determined by atomic absorption spectrophotometry in the Veterinary Institute Brno, Czech Republic, and expressed as mg.kg(-1) of wet tissue. Concentration of mercury, lead, and arsenic in most tissues of all analyzed fish types is lower than the maximal allowed concentration (MAC) in most countries. Cadmium concentration is also low in muscles and gonads, but kidney, liver, and gill concentrations exceed MAC value in most countries. Hasselquist, an endemic type for that region, differs from other fish types in the fact that it has very low cadmium concentration in liver and kidney, but the highest concentration of arsenic in most tissues, especially muscles. In muscles and gonads of all fish types analyzed, Pb is present in higher concentration than Cd, whereas in liver, gills, and particularly kidney, the situation is opposite, suggesting diverse metabolic pathways and unequal bioaccumulation of these two metals in different fish tissues. Although the region of the Nature Park Hutovo Blato in Bosnia and Herzegovina is not an agricultural territory, the intensive agricultural activities in the neighboring regions already result in high cadmium concentration in inner organs of fish species analyzed. Therefore, fish types in the freshwaters of the Park may be included in the human diet, but without inner organs and gills (or the whole head). PMID:17687582

Has-Schön, Elizabeta; Bogut, Ivan; Rajkovi?, Valentina; Bogut, Stjepan; Caci?, Milan; Horvati?, Janja

2008-01-01

221

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

2009-09-01

222

Freshwater Ecosystems  

NSDL National Science Digital Library

In this activity, learners create a freshwater ecosystem in a large plastic bottle. Learners cut and prepare bottles, then fill with water, aquatic plants, snails and fish. Learners observe their mini-ecosystem over time to see what changes--such as the color of the water, the water temperature, plant growth, and behavior and/or population of the snails or fish. The activity serves as a model for larger freshwater ecosystems such as ponds, lakes, rivers, streams, wetlands, reservoirs and groundwater.

2013-12-18

223

A holistic approach to taxonomic evaluation of two closely related endangered freshwater mussel species, the oyster mussel Epioblasma capsaeformis and tan riffleshell Epioblasma florentina walkeri (Bivalvia: Unionidae)  

USGS Publications Warehouse

Species in the genus Epioblasma have specialized life history requirements and represent the most endangered genus of freshwater mussels (Unionidae) in the world. A genetic characterization of extant populations of the oyster mussel E. capsaeformis and tan riffleshell E. florentina walkeri sensu late was conducted to assess taxonomic validity and to resolve conservation issues for recovery planning. These mussel species exhibit pronounced phenotypic variation, but were difficult to characterize phylogenetically using DNA sequences. Monophyletic lineages, congruent with phenotypic variation among species, were obtained only after extensive analysis of combined mitochondrial (1396 bp of 16S, cytochrome-b, and ND1) and nuclear (515 bp of ITS-1) DNA sequences. In contrast, analysis of variation at 10 hypervariable DNA microsatellite loci showed moderately to highly diverged populations based on FST and R ST values, which ranged from 0.12 to 0.39 and 0.15 to 0.71, respectively. Quantitative variation between species was observed in fish-host specificity, with transformation success of glochidia of E. capsaeformis significantly greater (P<0.05) on greenside darter Etheostoma blennioides, and that of E. f. walkeri significantly greater (P<0.05) on fantail darter Etheostoma flabellare. Lengths of glochidia differed significantly (P<0.001) among species and populations, with mean sizes ranging from 241 to 272 ??m. The texture and colour of the mantle-pad of E. capsaeformis sensu stricto is smooth and bluish-white, whereas that of E. f. walkeri is pustuled and brown, with tan mottling. Based on extensive molecular, morphological and life history data, the population of E. capsaeformis from the Duck River, Tennessee, USA is proposed as a separate species, and the population of E. f. walkeri from Indian Creek, upper Clinch River, Virginia, USA is proposed as a distinct subspecies.

Jones, J.W.; Neves, R.J.; Ahlstedt, S.A.; Hallerman, E.M.

2006-01-01

224

DEVELOPMENT OF A HUMAN BIOMARKER FOR CYANOBACTERIAL TOXINS- MICROCYSTINS  

EPA Science Inventory

Increasingly, cyanobacterial blooms are being reported worldwide due to several factors: eutrophication, climate change, and potentially greater scientific awareness and detection. During 1996, an outbreak of fatal cyanobacterial toxin intoxications occurred among a group of dia...

225

Freshwater Ecoregions of the World: A New Map of Biogeographic Units for Freshwater Biodiversity Conservation  

NSDL National Science Digital Library

We present a new map depicting the first global biogeographic regionalization of Earth's freshwater systems. This map of freshwater ecoregions is based on the distributions and compositions of freshwater fish species and incorporates major ecological and evolutionary patterns. Covering virtually all freshwater habitats on Earth, this ecoregion map, together with associated species data, is a useful tool for underpinning global and regional conservation planning efforts (particularly to identify outstanding and imperiled freshwater systems); for serving as a logical framework for large-scale conservation strategies; and for providing a global-scale knowledge base for increasing freshwater biogeographic literacy. Preliminary data for fish species compiled by ecoregion reveal some previously unrecognized areas of high biodiversity, highlighting the benefit of looking at the world's freshwaters through a new framework.

Robin Abell et al (WWF; )

2008-05-01

226

Population genetic patterns in sister species pairs sharing a single speciation event: a study of two species pairs of freshwater fishes  

E-print Network

This study asked whether population genetic structure of daughter species shows a pattern indicative of change caused by the speciation process. Fresh water fishes composing two geminate species pairs from a vicariant event ...

Carlson, Anna

2007-10-08

227

Plankton community succession in artificial systems subjected to cyanobacterial blooms removal using chitosan-modified soils.  

PubMed

Using artificial systems to simulate natural lake environments with cyanobacterial blooms, we investigated plankton community succession by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting and morphological method. With this approach, we explored potential ecological effects of a newly developed cyanobacterial blooms removal method using chitosan-modified soils. Results of PCR-DGGE and morphological identification showed that plankton communities in the four test systems were nearly identical at the beginning of the experiment. After applying the newly developed and standard removal methods, there was a shift in community composition, but neither chemical conditions nor plankton succession were significantly affected by the cyanobacteria removal process. The planted Vallisneria natans successfully recovered after cyanobacteria removal, whereas that in the box without removal process did not. Additionally, canonical correspondence analysis indicated that other than for zooplankton abundance, total phosphorus was the most important environmental predictor of planktonic composition. The present study and others suggest that dealing with cyanobacteria removal using chitosan-modified soils can play an important role in controlling cyanobacterial blooms in eutrophicated freshwater systems. PMID:18777048

Yan, Qingyun; Yu, Yuhe; Feng, Weisong; Pan, Gang; Chen, Hao; Chen, Juan; Yang, Bo; Li, Xuemei; Zhang, Xiang

2009-07-01

228

Pharmacology and toxicology of pahayokolide A, a bioactive metabolite from a freshwater species of Lyngbya isolated from the Florida Everglades  

PubMed Central

The genus of filamentous cyanobacteria, Lyngbya, has been found to be a rich source of bioactive metabolites. However, identification of such compounds from Lyngbya has largely focused on a few marine representatives. Here, we report on the pharmacology and toxicology of pahayokolide A from a freshwater isolate, Lyngbya sp. strain 15?2, from the Florida Everglades. Specifically, we investigated inhibition of microbial representatives and mammalian cell lines, as well as toxicity of the compound to both invertebrate and vertebrate models. Pahayokolide A inhibited representatives of Bacillus, as well as the yeast, Saccharomyces cerevisiae. Interestingly, the compound also inhibited several representatives of green algae that were also isolated from the Everglades. Pahayokolide A was shown to inhibit a number of cancer cell lines over a range of concentrations (IC50 varied from 2.13 to 44.57 ?M) depending on the cell-type. When tested against brine shrimp, pahayokolide was only marginally toxic at the highest concentrations tested (1 mg/mL). The compound was, however, acutely toxic to zebrafish embryos (LC50=2.15 ?M). Possible biomedical and environmental health aspects of the pahayokolides remain to be investigated; however, the identification of bioactive metabolites such as these demonstrates the potential of the Florida Everglades as source of new toxins and drugs. PMID:15683832

Berry, John P.; Gantar, Miroslav; Gawley, Robert E.; Wang, Minglei; Rein, Kathleen S.

2008-01-01

229

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

PubMed

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

2008-03-01

230

Liver alterations in two freshwater fish species (Carassius auratus and Danio rerio) following exposure to different TiO? nanoparticle concentrations.  

PubMed

The toxicity of titanium dioxide nanoparticles (TIO? NPs) and oxidative stress effects were studied in two freshwater fish species (Carassius auratus and Danio rerio) exposed for 21 days to different concentrations (0.01, 0.1, 1, 10, 100/mgL) of TiO? NPs and to a control (tap water). Additional fish were transferred to clean water for 14 days to assess the ability to recover from exposure to TiO? NPs. Activities of the enzyme glutathione-S-transferase (GST) and lipid peroxidation (LPO) (malondialdheyde) were measured as indicators of oxidative stress. Histological and ultra-structural changes in livers from both species of fish were evaluated by light and electron microscopy. Results show a general GST activity increase according to TiO? NPs concentrations, which is in agreement with data from LPO. After 21 days, GST activities decreased possibly caused by suppression of GST synthesis as a result of severe stress. Histological and ultra-structural analysis of livers from exposed fish show degeneration of the hepatic tissue and alterations in hepatocytes such as glycogen depletion and an increase in lipofucsin lysosome-like granules. After a depuration period a partial recovery for biochemical markers and cells was observed. The results suggest that TiO? promotes alterations in hepatic tissues compatible with oxidative stress. PMID:23931156

Diniz, Mário S; de Matos, António P Alves; Lourenço, Joana; Castro, Luísa; Peres, Isabel; Mendonça, Elsa; Picado, Ana

2013-10-01

231

Cyanobacterial defense mechanisms against foreign DNA transfer and their impact on genetic engineering.  

PubMed

Cyanobacteria display a large diversity of cellular forms ranging from unicellular to complex multicellular filaments or aggregates. Species in the group present a wide range of metabolic characteristics including the fixation of atmospheric nitrogen, resistance to extreme environments, production of hydrogen, secondary metabolites and exopolysaccharides. These characteristics led to the growing interest in cyanobacteria across the fields of ecology, evolution, cell biology and biotechnology. The number of available cyanobacterial genome sequences has increased considerably in recent years, with more than 140 fully sequenced genomes to date. Genetic engineering of cyanobacteria is widely applied to the model unicellular strains Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942. However the establishment of transformation protocols in many other cyanobacterial strains is challenging. One obstacle to the development of these novel model organisms is that many species have doubling times of 48 h or more, much longer than the bacterial models E. coli or B. subtilis. Furthermore, cyanobacterial defense mechanisms against foreign DNA pose a physical and biochemical barrier to DNA insertion in most strains. Here we review the various barriers to DNA uptake in the context of lateral gene transfer among microbes and the various mechanisms for DNA acquisition within the prokaryotic domain. Understanding the cyanobacterial defense mechanisms is expected to assist in the development and establishment of novel transformation protocols that are specifically suitable for this group. PMID:24510140

Stucken, Karina; Koch, Robin; Dagan, Tal

2013-01-01

232

Global diversity of hairworms (Nematomorpha: Gordiaceae) in freshwater  

Microsoft Academic Search

Freshwater hairworms (Gordiaceae) and marine hairworms (Nectonematoidea) comprise the phylum Nematomorpha. Only the freshwater\\u000a forms are discussed here. While freshwater hairworms develop as parasites of both aquatic and terrestrial arthropods, they\\u000a all enter fresh water to mate, oviposit and produce infective stages (preparasitic larvae). The global species diversity of\\u000a freshwater hairworms based on published descriptions is approximately 326 species and

George Poinar Jr

2008-01-01

233

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

PubMed

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

2012-10-01

234

Bryconops magoi and Bryconops collettei (Characiformes: Characidae), two new freshwater fish species from Venezuela, with comments on B. caudomaculatus (Günther)  

Microsoft Academic Search

Bryconops collettei and B. magoi are described from the Caura and Miamo (Bolívar State), Iguapo (Amazonas State) and Moquete (Anzoátegui State) rivers, Venezuela. These new species belong to the subgenus Bryconops, based upon apomorphies of the jaws and gill rakers and are compared with members of the subgenus. Based on morphology, meristics and color patterns, B. collettei and B. magoi

BARRY CHERNOFF; ANTONIO MACHADO-ALLISON

235

Use of chemical communication in the management of freshwater aquatic species that are vectors of human diseases or are invasive  

Microsoft Academic Search

Chemical communication occurs when both originator (signaller) and one or more receiver(s) possess specializations for chemical exchange of information. Chemical information can be used by a wide variety of species to locate food and mates, avoid predators and engage in social interactions. In this review, we focus on chemical signalling between mates or cues from nest sites or hosts by

Lynda D. Corkum; Rachelle M. Belanger

2007-01-01

236

Morphological variation in Echinorhynchustruttae Schrank, 1788 and the Echinorhynchusbothniensis Zdzitowiecki & Valtonen, 1987 species complex from freshwater fishes of northern Europe.  

PubMed

Echinorhynchustruttae and the Echinorhynchusbothniensis species complex are common parasites of salmoniform and other fishes in northern Europe. Echinorhynchusbothniensis and its sibling species Echinorhynchus 'bothniensis' are thought to be closely related to the Nearctic Echinorhynchusleidyi Van Cleave, 1924 based on morphological similarity and common usage of a mysid intermediate host. This study provides the first analysis of morphological and meristic variation in Echinorhynchustruttae and expands our knowledge of anatomical variability in the Echinorhynchusbothniensis group. Morphological variability in Echinorhynchustruttae was found to be far greater than previously reported, with part of the variance attributable to sexual dimorphism. Echinorhynchustruttae, the two species of the Echinorhynchusbothniensis group and Echinorhynchusleidyi displayed considerable interspecific overlap in the ranges of all conventional morphological characters. However, Proboscis profiler, a tool for detecting acanthocephalan morphotypes using multivariate analysis of hook morphometrics, successfully separated Echinorhynchustruttae from the other taxa. The Echinorhynchusbothniensis species group could not be reliably distinguished from Echinorhynchusleidyi (or each other), providing further evidence of the affinity of these taxa. Observations on the distribution of Echinorhynchustruttae in its definitive host population are also reported. PMID:24723769

Wayland, Matthew T

2013-01-01

237

Potamotrygon limai, sp. nov., a new species of freshwater stingray from the upper Madeira River system, Amazon basin (Chondrichthyes: Potamotrygonidae).  

PubMed

Potamotrygon limai, sp. nov., is described from the Jamari River, upper Madeira River system (Amazon basin), state of Rondônia, Brazil. This new species differs from congeners by presenting unique polygonal or concentric patterns formed by small whitish spots better defined over the posterior disc and tail-base regions. Potamotrygon limai, sp. nov., can be further distinguished from congeners in the same basin by other characters in combination, such as two to three rows of midtail spines converging to a single irregular row at level of caudal sting origin, proportions of head, tail and disc, patterns of dermal denticles on rostral, cranial and tail regions, among other features discussed herein. Potamotrygon limai, sp. nov., is most similar to, and occurs sympatrically with, P. scobina, and is distinguished from it by lacking ocellated spots on disc, by its characteristic polygonal pattern on posterior disc, a comparatively much shorter and broader tail, greater intensity of denticles on disc, more midtail spine rows at tail-base, and other features including size at maturity and meristic characters. Potamotrygon limai, sp. nov., is also distinguished from other species of Potamotrygon occurring in the Amazon region, except P. scobina, by presenting three angular cartilages (vs. two or one). This new species was discovered during a detailed taxonomic and morphological revision of the closely related species P. scobina, and highlights the necessity for thorough and all-embracing taxonomic studies, particularly in groups with pronounced endemism and morphological variability. PMID:24870898

Fontenelle, João Pedro; Da Silva, João Paulo C B; De Carvalho, Marcelo R

2014-01-01

238

Harmful freshwater algal blooms, with an emphasis on cyanobacteria.  

PubMed

Suspended algae, or phytoplankton, are the prime source of organic matter supporting food webs in freshwater ecosystems. Phytoplankton productivity is reliant on adequate nutrient supplies; however, increasing rates of nutrient supply, much of it manmade, fuels accelerating primary production or eutrophication. An obvious and problematic symptom of eutrophication is rapid growth and accumulations of phytoplankton, leading to discoloration of affected waters. These events are termed blooms. Blooms are a prime agent of water quality deterioration, including foul odors and tastes, deoxygenation of bottom waters (hypoxia and anoxia), toxicity, fish kills, and food web alterations. Toxins produced by blooms can adversely affect animal (including human) health in waters used for recreational and drinking purposes. Numerous freshwater genera within the diverse phyla comprising the phytoplankton are capable of forming blooms; however, the blue-green algae (or cyanobacteria) are the most notorious bloom formers. This is especially true for harmful toxic, surface-dwelling, scum-forming genera (e.g., Anabaena, Aphanizomenon, Nodularia, Microcystis) and some subsurface bloom-formers (Cylindrospermopsis, Oscillatoria) that are adept at exploiting nutrient-enriched conditions. They thrive in highly productive waters by being able to rapidly migrate between radiance-rich surface waters and nutrient-rich bottom waters. Furthermore, many harmful species are tolerant of extreme environmental conditions, including very high light levels, high temperatures, various degrees of desiccation, and periodic nutrient deprivation. Some of the most noxious cyanobacterial bloom genera (e.g., Anabaena, Aphanizomenon, Cylindrospermopsis, Nodularia) are capable of fixing atmospheric nitrogen (N2), enabling them to periodically dominate under nitrogen-limited conditions. Cyanobacteria produce a range of organic compounds, including those that are toxic to higher-ranked consumers, from zooplankton to further up the food chain. Both N2- and non-N2-fixing genera participate in mutualistic and symbiotic associations with microorganisms, higher plants, and animals. These associations appear to be of great benefit to their survival and periodic dominance. In this review, we address the ecological impacts and environmental controls of harmful blooms, with an emphasis on the ecology, physiology, and management of cyanobacterial bloom taxa. Combinations of physical, chemical, and biotic features of natural waters function in a synergistic fashion to determine the sensitivity of water bodies. In waters susceptible to blooms, human activities in water- and airsheds have been linked to the extent and magnitudes of blooms. Control and management of cyanobacterial and other phytoplankton blooms invariably includes nutrient input constraints, most often focused on nitrogen (N) and/or phosphorus (P). The types and amount of nutrient input constraints depend on hydrologic, climatic, geographic, and geologic factors, which interact with anthropogenic and natural nutrient input regimes. 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 harmful blooms. In some systems where hydrologic manipulations (i.e., plentiful water supplies) are possible, reducing the water residence time by enhanced flushing and artificial mixing (in conjunction with nutrient input constraints) can be particularly effective alternatives. Implications of various management strategies, based on combined ecophysiological and environmental considerations, are discussed. PMID:12805693

Paerl, H W; Fulton, R S; Moisander, P H; Dyble, J

2001-04-01

239

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. PMID:20411119

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

2010-01-01

240

Sensitive and rapid detection of freshwater crustacean Spiroplasmas by ISRs-sequence-targeted species-specific primers  

Microsoft Academic Search

For the rapid and sensitive identification of the Spiroplasmas in the Chinese mitten crab Eriocheir sinensis, a species-specific PCR primer-pair was designed according to Spiroplasma sp. strain CRAB-specific segments of the previously sequenced 16S–23S rRNA intergenic spacer region (ISR). The PCR-mediated\\u000a assay allowed identification of Spiroplasmas from different aquatic crustacean hosts, E. sinensis and red swamp crayfish Procambarus clarkia, in

Keran Bi; Wei Gu; Wen Wang

2008-01-01

241

Planarian (Dugesia polychroa) predation on freshwater gastropod eggs depends on prey species, clutch morphology, and egg size  

Microsoft Academic Search

Though triclad planarias could limit littoral snail recruitment by preying on eggs with their muscular ventral pharynx, planarian predation on eggs has never been quantified. Intact egg clutches encompassing eight snail species × three developmental stages were offered to Dugesia (= Schmidtea) polychroa (Paludicola: Dugesiidae) individuals (body length = 6–12 mm) in one-on-one, no-choice 24-h feeding trials to gain a

Francesco Paolo Miccoli; Marco Giustini; Bruno Cicolani

2011-01-01

242

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.  

PubMed

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

2013-04-01

243

Cyanobacterial Community Structure In Lithifying Mats of A Yellowstone Hotspring-Implications for Precambrian Stromatolite Biocomplexity  

NASA Technical Reports Server (NTRS)

Denaturing Gradient Gel Electrophoresis (DGGE) of partial 16S rRNA gene sequences was used to investigate the molecular biodiversity of cyanobacterial communities inhabiting various lithified morpho-structures in two hotsprings of Yellowstone National Park. These morpho-structures - flat-topped columns, columnar cones, and ridged cones - resemble ancient stromatolites, which are possibly biogenic in origin. The top, middle and bottom sections of these lithified morpho-structures, as well as surrounding non-lithified mats were analyzed to determine the vertical and spatial distribution of cyanobacterial communities. Results from DGGE indicate that the cyanobacterial community composition of lithified morpho-structures (flat-topped columns, columnar cones, and ridged cones) were largely similar in vertical distribution as well as among the morpho-structures being studied. Preliminary results indicate that the cyanobacterial communities in these lithified morpho-structures were significantly different from communities in surrounding non-lithified mats. These results provide additional support to the theory that certain Phormidium/Leptolyngbya species are involved in the morphogenesis of lithifying morpho-structures in hotsprings and may have played a role in the formation of ancient stromatolites.

Lau, Evan; Nash, C. Z.; Vogler, D. R.; Cullings, K.; DeVincenzi, Donald (Technical Monitor)

2002-01-01

244

Characterization of cyanobacterial communities from high-elevation lakes in the Bolivian Andes  

NASA Astrophysics Data System (ADS)

The Bolivian Altiplano is a harsh environment for life with high solar irradiation (visible and UVR), below freezing temperatures, and some of the lowest precipitation rates on the planet. However, microbial life is visibly abundant in small isolated refugia of spring or snowmelt-fed lakes. In this study, we characterized the cyanobacterial composition of a variety of microbial mats present in three lake systems: Laguna Blanca, Laguna Verde (elevation 4300 m), and a summit lake in the Licancabur Volcano cone (elevation 5970 m). These lakes and their adjacent geothermal springs present an interesting diversity of environments within a geographically small region (5 km2). From these sites, 78 cyanobacterial cultures were isolated in addition to ˜400 cyanobacterial 16S rRNA gene sequences from environmental genomic DNA. Based on microscopy, cultivation, and molecular analyses, these communities contained many heterocytous, nitrogen-fixing cyanobacteria (e.g., Calothrix, Nostoc, Nodularia) as well as a large number of cyanobacteria belonging to the form-genus Leptolyngbya. More than a third (37%) of all taxa in this study were new species (?96% 16S rRNA gene sequence identity), and 11% represented new and novel taxa distantly related (?93% identity) to any known cyanobacteria. This is one of the few studies to characterize cyanobacterial communities based on both cultivation-dependent and cultivation-independent analyses.

Fleming, Erich D.; Prufert-Bebout, Leslie

2010-06-01

245

Toxicity of lead (Pb) to freshwater green algae: development and validation of a bioavailability model and inter-species sensitivity comparison.  

PubMed

Scientifically sound risk assessment and derivation of environmental quality standards for lead (Pb) in the freshwater environment are hampered by insufficient data on chronic toxicity and bioavailability to unicellular green algae. Here, we first performed comparative chronic (72-h) toxicity tests with three algal species in medium at pH 6, containing 4 mg fulvic acid (FA)/L and containing organic phosphorous (P), i.e. glycerol-2-phosphate, instead of PO4(3-) to prevent lead-phosphate mineral precipitation. Pseudokirchneriella subcapitata was 4-fold more sensitive to Pb than Chlorella kesslerii, with Chlamydomonas reinhardtii in the middle. The influence of medium physico-chemistry was therefore investigated in detail with P. subcapitata. In synthetic test media, higher concentrations of fulvic acid or lower pH protected against toxicity of (filtered) Pb to P. subcapitata, while effects of increased Ca or Mg on Pb toxicity were less clear. When toxicity was expressed on a free Pb(2+) ion activity basis, a log-linear, 260-fold increase of toxicity was observed between pH 6.0 and 7.6. Effects of fulvic acid were calculated to be much more limited (1.9-fold) and were probably even non-existent (depending on the affinity constant for Pb binding to fulvic acid that was used for calculating speciation). A relatively simple bioavailability model, consisting of a log-linear pH effect on Pb(2+) ion toxicity linked to the geochemical speciation model Visual Minteq (with the default NICA-Donnan description of metal and proton binding to fulvic acid), provided relatively accurate toxicity predictions. While toxicity of (filtered) Pb varied 13.7-fold across 14 different test media (including four Pb-spiked natural waters) with widely varying physico-chemistry (72h-EC50s between 26.6 and 364 ?g/L), this bioavailability model displayed mean and maximum prediction errors of only 1.4 and 2.2-fold, respectively, thus indicating the potential usefulness of this bioavailability model to reduce uncertainty in site-specific risk assessment. A model-based comparison with other species indicated that the sensitivity difference between P. subcapitata and two of the most chronically Pb-sensitive aquatic invertebrates (the crustacean Ceriodaphnia dubia and the snail Lymnaea stagnalis) is strongly pH dependent, with P. subcapitata becoming the most sensitive of the three at pH > 7.4. This indicates that inter-species differences in Pb bioavailability relationships should be accounted for in risk assessment and in the derivation of water quality criteria or environmental quality standards for Pb. The chronic toxicity data with three algae species and the bioavailability model presented here will help to provide a stronger scientific basis for evaluating ecological effects of Pb in the freshwater environment. PMID:25089923

De Schamphelaere, K A C; Nys, C; Janssen, C R

2014-10-01

246

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

2003-01-01

247

Are cyanobacterial blooms trophic dead ends?  

PubMed

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

2013-06-01

248

Freshwater Molluscs  

Microsoft Academic Search

Freshwater mollusc shells are among the best and most extensively preserved fossils in lacustrine sediments. These molluscs\\u000a are useful because they occur in a broad range of paleoenvironments. As a result, they have been used to reconstruct former\\u000a stream confluences, provide a basis for biostratigraphic zonation of sedimentary sequences in lake basins, and reconstruct\\u000a habitat and climatic conditions. Because many

Barry B. Miller; Michael J. S. Tevesz

249

Phylogenetic Characterization and Prevalence of “Spirobacillus cienkowskii,” a Red-Pigmented, Spiral-Shaped Bacterial Pathogen of Freshwater Daphnia Species?  

PubMed Central

Microscopic examination of the hemolymph from diseased daphniids in 17 lakes in southwestern Michigan and five rock pools in southern Finland revealed the presence of tightly coiled bacteria that bore striking similarities to the drawings of a morphologically unique pathogen, “Spirobacillus cienkowskii,” first described by Elya Metchnikoff more than 100 years ago. The uncultivated microbe was identified as a deeply branching member of the Deltaproteobacteria through phylogenetic analyses of two conserved genes: the 16S rRNA-encoding gene (rrs) and the ?-subunit of topoisomerase (gyrB). Fluorescence in situ hybridization confirmed that the rRNA gene sequence originated from bacteria with the tightly coiled morphology. Microscopy and PCR amplification with pathogen-specific primers confirmed infections by this bacterium in four species of Daphnia: Daphnia dentifera, D. magna, D. pulicaria, and D. retrocurva. Extensive field surveys reveal that this bacterium is widespread geographically and able to infect many different cladoceran species. In a survey of populations of D. dentifera in lakes in Michigan, we found the bacterium in 17 of 18 populations studied. In these populations, 0 to 12% of the individuals were infected, with an average of 3% during mid-summer and early autumn. Infections were less common in rock pool populations of D. magna in southern Finland, where the pathogen was found in 5 of 137 populations. The broad geographic distribution, wide host range, and high virulence of S. cienkowskii suggest it plays an important role in the ecology and evolution of daphniids. PMID:18192404

Rodrigues, Jorge L. M.; Duffy, Meghan A.; Tessier, Alan J.; Ebert, Dieter; Mouton, Laurence; Schmidt, Thomas M.

2008-01-01

250

Two new species of Parspina Pearse, 1920 (Digenea: Cryptogonimidae) from freshwater fishes (Gymnotiformes) of the Paraná River basin in Argentina.  

PubMed

Two new species of the cryptogonimid genus Parspina Pearse, 1920 are described from gymnotiform fishes of the Paraná River basin, P. carapo n. sp. from the banded knifefish Gymnotus carapo Linnaeus and P. virescens n. sp. from the glass knifefish Eigenmannia virescens (Valenciennes). Parspina carapo differs from P. virescens in the number of oral spines (32-39 vs 30-33) and their length (28-47 vs 16-28 ?m), the distribution of tegumental spines and their anchorage, the types of sensory papillae on the body surface (three vs two types), the extent of body length posterior to the caeca (5 vs 13% of the total body length), the dimensions of the pars prostatica (52 × 34 vs 24 × 10 ?m), and in the absence of a gonotyl (vs presence). Both P. carapo and P. virescens differ from P. bagre Pearse, 1920 and P. argentinensis (Szidat, 1954) in the number of oral spines (20-21 and 21-28 in the latter pair) and their length (28-32 and 35-60 ?m), and in total body length. Additionally, the two new species differ from P. argentinensis in the arrangement of the vitelline follicles (one continuous band vs two groups on each side of the body) and in having a smaller pars prostatica (149 × 49 ?m in the latter). Parspina carapo is the fifth intestinal helminth found in G. carapo, and P. virescens is the first found in E. virescens. PMID:21805392

de Núñez, Margarita C Ostrowski; Arredondo, Nathalia J; de Pertierra, Alicia A Gil

2011-09-01

251

A comparison of diel nest temperature and nest site selection for two sympatric species of freshwater turtles  

SciTech Connect

Diel nest temperature profiles were recorded form natural nests of eastern mud turtles (Kinosternon subrubrum) and Florida cooters (Pseudemys floridana) to determine whether nest microhabitat selection compensates for the effect of interspecific differences in nest depth on nest temperature. Kinosternon subrubrum nest depths were significantly shallower than those of P. floridana (t = 2.93, P < 0.01). We predicted that differences in nest depth would result in K. subrubrum nests being cooler at night and warmer during daylight than the deeper P. floridana nests. Diel temperature patterns agreed with out predictions at night, but P. floridana nest temperatures were not lower than K. subrubrum nest temperatures during the day. Soil composition, slope and soil moisture were similar for the nest of both species. However, the amount of sunlight reaching the soil above K. subrubrum nest sites was substantially less than the amount above P. floridana nest sites. We suggest that these species select habitats for oviposition that differ in the amount and types of vegetative cover, which in turn affect exposure to sunlight and ultimately nest temperature. 27 refs., 2 figs.

Bodie, J.R.; Burke, V.J. [Univ. of Georgia, Aiken, SC (United States); Smith, K.R. [Southeastern Louisiana Univ., Hammond, LA (United States)

1996-07-01

252

Freshwater Mammals as Indicators of Habitat Condition  

Microsoft Academic Search

\\u000a Among the mammals within the current extent of the European Union, there are no truly aquatic freshwater species. There are,\\u000a however, several species that are semi-aquatic and that in one way or the other are associated with or depend on freshwater\\u000a habitats. There is also one seal species that inhabits brackish waters in the Baltic Sea as well as the

Michael Schneider

253

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

254

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

2008-01-01

255

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

PubMed

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

2012-04-01

256

Secondary invasion of the round goby into high diversity Great Lakes tributaries and species at risk hotspots: potential new concerns for endangered freshwater species  

Microsoft Academic Search

The round goby (Neogobius melanostomus) first invaded North America in 1990 when it was discovered in the St. Clair River. Despite more than 15 years of potential\\u000a invasion, many Great Lakes’ lotic systems remained uninvaded. Recently, we captured the round goby from several Great Lakes\\u000a tributaries known as species-at-risk hotspots. With a combination of field sampling of round gobies and literature

Mark Poos; Alan J. Dextrase; Astrid N. Schwalb; Josef D. Ackerman

2010-01-01

257

Temporal variation in community composition, pigmentation, and Fv/Fm of desert cyanobacterial soil crusts  

USGS Publications Warehouse

Summers on the Colorado Plateau (USA) are typified by harsh conditions such as high temperatures, brief soil hydration periods, and high UV and visible radiation. We investigated whether community composition, physiological status, and pigmentation might vary in biological soil crusts as a result of such conditions. Representative surface cores were sampled at the ENE, WSW, and top microaspects of 20 individual soil crust pedicels at a single site in Canyonlands National Park, Utah, in spring and fall of 1999. Frequency of cyanobacterial taxa, pigment concentrations, and dark adapted quantum yield (Fv/Fm) were measured for each core. The frequency of major cyanobacterial taxa was lower in the fall compared to spring. The less-pigmented cyanobacterium Microcoleus vaginatus showed significant mortality when not in the presence of Nostoc spp. and Scytonema myochrous (Dillw.) Agardh. (both synthesizers of UV radiation-linked pigments) but had little or no mortality when these species were abundant. We hypothesize that the sunscreen pigments produced by Nostoc and Scytonema in the surface of crusts protect other, less-pigmented taxa. When fall and spring samples were compared, overall cyanobacterial frequency was lower in fall, while sunscreen pigment concentrations, chlorophyll a concentration, and Fv/Fm were higher in fall. The ratio of cyanobacterial frequency/chlorophyll a concentrations was 2-3 times lower in fall than spring. Because chlorophyll a is commonly used as a surrogate measure of soil cyanobacterial biomass, these results indicate that seasonality needs to be taken into consideration. In the fall sample, most pigments associated with UV radiation protection or repair were at their highest concentrations on pedicel tops and WSW microaspects, and at their lowest concentrations on ENE microaspects. We suggest that differential pigment concentrations between microaspects are induced by varying UV radiation dosage at the soil surface on these different microaspects.

Bowker, M.A.; Reed, S.C.; Belnap, J.; Phillips, S.L.

2002-01-01

258

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

PubMed

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

2012-05-01

259

Cochliopodium gallicum n. sp. (Himatismenida), an amoeba bearing unique scales, from cyanobacterial mats in the Camargue (France)  

Microsoft Academic Search

Cochliopodium gallicum n. sp., isolated from cyanobacterial mats in the Camargue (France) is the smallest marine species of Cochliopodium to date. Its unusual tectum consists of flat plate-shaped scales with honeycomb-like centres, underlain by a layer of filamentous structures connected to each other in the basal and apical parts. The tectum is very fine and can be easily lost under

Alexander Kudryavtsev; Alexey Smirnov

2006-01-01

260

Uptake and metabolism of benzo(a)pyrene absorbed to sediment by the freshwater invertebrate species Chironomus riparius and Sphaerium corneum  

SciTech Connect

The polyaromatic hydrocarbon (PAH) Benzo(a)pyrene (BP) is a widespread contaminant, which is known to be carcinogenic in mammals after ic activation. BP is released into the environment and the water as a by-product of combustion of fossil and recent material (fuel, wood) in industry, traffic and households and is also released by natural sources. Most of the PAHs are highly lipophilic and therefore bound to humic substances, dissolved macromolecules and particulate matter which are at least deposited in the aquatic sediments. The BP concentrations in sediments of pristine waters do normally not exceed 1 {mu}g/g dry weight (dw). In polluted waters of industrial areas, the BP concentration may increase up to 100 {mu}g/g dw. The risk for environmental health caused by such sediment bound PAHs can be assessed by using BP as a model substance. One aim of this study was to investigate if the sediment bound BP is bioavailable to sediment dwelling organisms. For this purpose we examined the uptake of sediment bound BP. The metabolism of PAHs in insects has been investigated, however, only little is known about the Phase I and Phase II metabolism in clams, especially in freshwater species. The organisms choosen were two sediment inhabiting invertebrates, the larvae of the midge Chironomus riparius and the European fingernail clam Sphaerium corneum. Also investigated was the question of whether the BP taken up by the test organisms undergoes metabolic activation, since the toxicity of BP is modulated by metabolism. 11 refs., 3 figs., 4 tabs.

Borchert, J.; Karbe, L.; Westendorf, J. [Univ. of Hamburg (Germany)] [Univ. of Hamburg (Germany)

1997-01-01

261

Potent toxins in Arctic environments--presence of saxitoxins and an unusual microcystin variant in Arctic freshwater ecosystems.  

PubMed

Cyanobacteria are the predominant phototrophs in freshwater ecosystems of the polar regions where they commonly form extensive benthic mats. Despite their major biological role in these ecosystems, little attention has been paid to their physiology and biochemistry. An important feature of cyanobacteria from the temperate and tropical regions is the production of a large variety of toxic secondary metabolites. In Antarctica, and more recently in the Arctic, the cyanobacterial toxins microcystin and nodularin (Antarctic only) have been detected in freshwater microbial mats. To date other cyanobacterial toxins have not been reported from these locations. Five Arctic cyanobacterial communities were screened for saxitoxin, another common cyanobacterial toxin, and microcystins using immunological, spectroscopic and molecular methods. Saxitoxin was detected for the first time in cyanobacteria from the Arctic. In addition, an unusual microcystin variant was identified using liquid chromatography-mass spectrometry. Gene expression analyses confirmed the analytical findings, whereby parts of the sxt and mcy operon involved in saxitoxin and microcystin synthesis, were detected and sequenced in one and five of the Arctic cyanobacterial samples, respectively. The detection of these compounds in the cryosphere improves the understanding of the biogeography and distribution of toxic cyanobacteria globally. The sequences of sxt and mcy genes provided from this habitat for the first time may help to clarify the evolutionary origin of toxin production in cyanobacteria. PMID:23648386

Kleinteich, Julia; Wood, Susanna A; Puddick, Jonathan; Schleheck, David; Küpper, Frithjof C; Dietrich, Daniel

2013-11-25

262

Engineered Transcriptional Systems for Cyanobacterial Biotechnology  

PubMed Central

Cyanobacteria can function as solar-driven biofactories thanks to their ability to perform photosynthesis and the ease with which they are genetically modified. In this review, we discuss transcriptional parts and promoters available for engineering cyanobacteria. First, we go through special cyanobacterial characteristics that may impact engineering, including the unusual cyanobacterial RNA polymerase, sigma factors and promoter types, mRNA stability, circadian rhythm, and gene dosage effects. Then, we continue with discussing component characteristics that are desirable for synthetic biology approaches, including decoupling, modularity, and orthogonality. We then summarize and discuss the latest promoters for use in cyanobacteria regarding characteristics such as regulation, strength, and dynamic range and suggest potential uses. Finally, we provide an outlook and suggest future developments that would advance the field and accelerate the use of cyanobacteria for renewable biotechnology. PMID:25325057

Camsund, Daniel; Lindblad, Peter

2014-01-01

263

Diversity, distribution and hydrocarbon biodegradation capabilities of microbial communities in oil-contaminated cyanobacterial mats from a constructed wetland.  

PubMed

Various types of cyanobacterial mats were predominant in a wetland, constructed for the remediation of oil-polluted residual waters from an oil field in the desert of the south-eastern Arabian Peninsula, although such mats were rarely found in other wetland systems. There is scarce information on the bacterial diversity, spatial distribution and oil-biodegradation capabilities of freshwater wetland oil-polluted mats. Microbial community analysis by Automated Ribosomal Spacer Analysis (ARISA) showed that the different mats hosted distinct microbial communities. Average numbers of operational taxonomic units (OTUsARISA) were relatively lower in the mats with higher oil levels and the number of shared OTUsARISA between the mats was <60% in most cases. Multivariate analyses of fingerprinting profiles indicated that the bacterial communities in the wetland mats were influenced by oil and ammonia levels, but to a lesser extent by plant density. In addition to oil and ammonia, redundancy analysis (RDA) showed also a significant contribution of temperature, dissolved oxygen and sulfate concentration to the variations of the mats' microbial communities. Pyrosequencing yielded 282,706 reads with >90% of the sequences affiliated to Proteobacteria (41% of total sequences), Cyanobacteria (31%), Bacteriodetes (11.5%), Planctomycetes (7%) and Chloroflexi (3%). Known autotrophic (e.g. Rivularia) and heterotrophic (e.g. Azospira) nitrogen-fixing bacteria as well as purple sulfur and non-sulfur bacteria were frequently encountered in all mats. On the other hand, sequences of known sulfate-reducing bacteria (SRBs) were rarely found, indicating that SRBs in the wetland mats probably belong to yet-undescribed novel species. The wetland mats were able to degrade 53-100% of C12-C30 alkanes after 6 weeks of incubation under aerobic conditions. We conclude that oil and ammonia concentrations are the major key players in determining the spatial distribution of the wetland mats' microbial communities and that these mats contribute directly to the removal of hydrocarbons from oil field wastewaters. PMID:25514025

Abed, Raeid M M; Al-Kharusi, Samiha; Prigent, Stephane; Headley, Tom

2014-01-01

264

Diversity, Distribution and Hydrocarbon Biodegradation Capabilities of Microbial Communities in Oil-Contaminated Cyanobacterial Mats from a Constructed Wetland  

PubMed Central

Various types of cyanobacterial mats were predominant in a wetland, constructed for the remediation of oil-polluted residual waters from an oil field in the desert of the south-eastern Arabian Peninsula, although such mats were rarely found in other wetland systems. There is scarce information on the bacterial diversity, spatial distribution and oil-biodegradation capabilities of freshwater wetland oil-polluted mats. Microbial community analysis by Automated Ribosomal Spacer Analysis (ARISA) showed that the different mats hosted distinct microbial communities. Average numbers of operational taxonomic units (OTUsARISA) were relatively lower in the mats with higher oil levels and the number of shared OTUsARISA between the mats was <60% in most cases. Multivariate analyses of fingerprinting profiles indicated that the bacterial communities in the wetland mats were influenced by oil and ammonia levels, but to a lesser extent by plant density. In addition to oil and ammonia, redundancy analysis (RDA) showed also a significant contribution of temperature, dissolved oxygen and sulfate concentration to the variations of the mats’ microbial communities. Pyrosequencing yielded 282,706 reads with >90% of the sequences affiliated to Proteobacteria (41% of total sequences), Cyanobacteria (31%), Bacteriodetes (11.5%), Planctomycetes (7%) and Chloroflexi (3%). Known autotrophic (e.g. Rivularia) and heterotrophic (e.g. Azospira) nitrogen-fixing bacteria as well as purple sulfur and non-sulfur bacteria were frequently encountered in all mats. On the other hand, sequences of known sulfate-reducing bacteria (SRBs) were rarely found, indicating that SRBs in the wetland mats probably belong to yet-undescribed novel species. The wetland mats were able to degrade 53–100% of C12–C30 alkanes after 6 weeks of incubation under aerobic conditions. We conclude that oil and ammonia concentrations are the major key players in determining the spatial distribution of the wetland mats’ microbial communities and that these mats contribute directly to the removal of hydrocarbons from oil field wastewaters. PMID:25514025

Abed, Raeid M. M.; Al-Kharusi, Samiha; Prigent, Stephane; Headley, Tom

2014-01-01

265

DNA BARCODING DNA barcoding of Cuban freshwater fishes: evidence for  

E-print Network

DNA BARCODING DNA barcoding of Cuban freshwater fishes: evidence for cryptic species and taxonomic subunit I) were used to barcode 126 individuals, representing 27 taxonomically recognized species in 17 of the DNA barcodes for cataloguing Cuban freshwater fish species and for identifying those groups

Bernatchez, Louis

266

Application of Multispectral and Hyperspectral Remote Sensing For Detection of Freshwater Harmful Algal Blooms  

NASA Astrophysics Data System (ADS)

Freshwater Cyanobacterial Harmful algal blooms (CHABs) represent a pressing and apparently increasing threat to both human and environmental health. In California, toxin producing blooms of several species, including Aphanizomenon, Microcystis, Lyngbya, and Anabaena are common; toxins from these blooms have been linked to impaired drinking water, domestic and wild animal deaths, and increasing evidence for toxin transfer to coastal marine environments, including the death of several California sea otters, a threatened marine species. California scientists and managers are under increasing pressure to identify and mitigate these potentially toxic blooms, but point-source measurements and grab samples have been less than effective. There is increasing awareness that these toxic events are both spatially widespread and ephememeral, leading to the need for better monitoring methods applicable to large spatial and temporal scales. Based on monitoring in several California water bodies, it appears that Aphanizomenon blooms frequently precede dangerous levels of toxins from Microcystis. We are exploring new detection methods for identifying CHABs and potentially distinguishing between blooms of the harmful cyanobacteria Aphanizomenon and Microcystis using remote sensing reflectance from a variety of airborne and satellite sensors. We suggest that Aphanizomenon blooms could potentially be used as an early warning of more highly toxic subsequent blooms, and that these methods, combined with better toxin monitoring, can lead to improved understanding and prediction of CHABs by pinpointing problematic watersheds.

Kudela, R. M.; Accorsi, E.; Austerberry, D.; Palacios, S. L.

2013-12-01

267

Harmful cyanobacterial blooms: causes, consequences, and controls.  

PubMed

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

2013-05-01

268

Occurrence and transfer of a cyanobacterial neurotoxin ?-methylamino-L-alanine within the aquatic food webs of Gonghu Bay (Lake Taihu, China) to evaluate the potential human health risk.  

PubMed

To evaluate the health risk of cyanobacterial blooms, the levels of the neurotoxic non-protein amino acid, ?-methylamino-l-alanine (BMAA), was investigated in the freshwater ecosystem of Gonghu Bay in Lake Taihu. Lake Taihu is a large shallow lake contaminated by the excessive growth of Microcystis. Since BMAA has been measured in diverse cyanobacteria in different ecosystems all over the world, BMAA might also occur in Gonghu Bay. A long term monitoring of BMAA was done by HPLC-MS/MS method in cyanobacteria, mollusks, crustaceans and various fish species at different trophic levels of ecosystems in Gonghu Bay, some of which were popularly consumed by humans. Over the entire sampling period, the total average BMAA content in cyanobacteria, mollusks, crustaceans and various fish species were 4.12, 3.21, 3.76, and 6.05?gBMAA/g dry weight, respectively. Thus, BMAA could be biosynthesized by the blooming cyanobacteria in which Microcystis dominates. This toxin can be transferred through ascending trophic levels of the aquatic ecosystem in Gonghu Bay. The bioaccumulation of BMAA was observed in aquatic animals, especially in some fish species during the bloom-outbreak and bloom-decline phases. The discovery of the chronic neurotoxin BMAA in a large limnic ecosystem together with possible pathways of accumulation within major food webs deserves serious consideration due to its potential long-term risk to human health. PMID:24055662

Jiao, Yiying; Chen, Qiankun; Chen, Xu; Wang, Xin; Liao, Xuewei; Jiang, Lijuan; Wu, Jun; Yang, Liuyan

2014-01-15

269

Metatranscriptomic evidence for co-occurring top-down and bottom-up controls on toxic cyanobacterial communities.  

PubMed

Little is known about the molecular and physiological function of co-occurring microbes within freshwater cyanobacterial harmful algal blooms (cHABs). To address this, community metatranscriptomes collected from the western basin of Lake Erie during August 2012 were examined. Using sequence data, we tested the hypothesis that the activity of the microbial community members is independent of community structure. Predicted metabolic and physiological functional profiles from spatially distinct metatranscriptomes were determined to be ?90% similar between sites. Targeted analysis of Microcystis aeruginosa, the historical causative agent of cyanobacterial harmful algal blooms over the past ?20 years, as well as analysis of Planktothrix agardhii and Anabaena cylindrica, revealed ongoing transcription of genes involved in microcystin toxin synthesis as well as the acquisition of both nitrogen and phosphorus, nutrients often implicated as independent bottom-up drivers of eutrophication in aquatic systems. Transcription of genes involved in carbon dioxide (CO2) concentration and metabolism also provided support for the alternate hypothesis that high-pH conditions and dense algal biomass result in CO2-limiting conditions that further favor cyanobacterial dominance. Additionally, the presence of Microcystis-specific cyanophage sequences provided preliminary evidence of possible top-down virus-mediated control of cHAB populations. Overall, these data provide insight into the complex series of constraints associated with Microcystis blooms that dominate the western basin of Lake Erie during summer months, demonstrating that multiple environmental factors work to shape the microbial community. PMID:25662977

Steffen, Morgan M; Belisle, B Shafer; Watson, Sue B; Boyer, Gregory L; Bourbonniere, Richard A; Wilhelm, Steven W

2015-05-01

270

Temperature and Cyanobacterial Bloom Biomass Influence Phosphorous Cycling in Eutrophic Lake Sediments  

PubMed Central

Cyanobacterial blooms frequently occur in freshwater lakes, subsequently, substantial amounts of decaying cyanobacterial bloom biomass (CBB) settles onto the lake sediments where anaerobic mineralization reactions prevail. Coupled Fe/S cycling processes can influence the mobilization of phosphorus (P) in sediments, with high releases often resulting in eutrophication. To better understand eutrophication in Lake Taihu (PRC), we investigated the effects of CBB and temperature on phosphorus cycling in lake sediments. Results indicated that added CBB not only enhanced sedimentary iron reduction, but also resulted in a change from net sulfur oxidation to sulfate reduction, which jointly resulted in a spike of soluble Fe(II) and the formation of FeS/FeS2. Phosphate release was also enhanced with CBB amendment along with increases in reduced sulfur. Further release of phosphate was associated with increases in incubation temperature. In addition, CBB amendment resulted in a shift in P from the Fe-adsorbed P and the relatively unreactive Residual-P pools to the more reactive Al-adsorbed P, Ca-bound P and organic-P pools. Phosphorus cycling rates increased on addition of CBB and were higher at elevated temperatures, resulting in increased phosphorus release from sediments. These findings suggest that settling of CBB into sediments will likely increase the extent of eutrophication in aquatic environments and these processes will be magnified at higher temperatures. PMID:24682039

Chen, Mo; Ye, Tian-Ran; Krumholz, Lee R.; Jiang, He-Long

2014-01-01

271

Temperature and cyanobacterial bloom biomass influence phosphorous cycling in eutrophic lake sediments.  

PubMed

Cyanobacterial blooms frequently occur in freshwater lakes, subsequently, substantial amounts of decaying cyanobacterial bloom biomass (CBB) settles onto the lake sediments where anaerobic mineralization reactions prevail. Coupled Fe/S cycling processes can influence the mobilization of phosphorus (P) in sediments, with high releases often resulting in eutrophication. To better understand eutrophication in Lake Taihu (PRC), we investigated the effects of CBB and temperature on phosphorus cycling in lake sediments. Results indicated that added CBB not only enhanced sedimentary iron reduction, but also resulted in a change from net sulfur oxidation to sulfate reduction, which jointly resulted in a spike of soluble Fe(II) and the formation of FeS/FeS2. Phosphate release was also enhanced with CBB amendment along with increases in reduced sulfur. Further release of phosphate was associated with increases in incubation temperature. In addition, CBB amendment resulted in a shift in P from the Fe-adsorbed P and the relatively unreactive Residual-P pools to the more reactive Al-adsorbed P, Ca-bound P and organic-P pools. Phosphorus cycling rates increased on addition of CBB and were higher at elevated temperatures, resulting in increased phosphorus release from sediments. These findings suggest that settling of CBB into sediments will likely increase the extent of eutrophication in aquatic environments and these processes will be magnified at higher temperatures. PMID:24682039

Chen, Mo; Ye, Tian-Ran; Krumholz, Lee R; Jiang, He-Long

2014-01-01

272

Mapping freshwater deltaic wetlands and aquatic habitats at multiple scales with high-resolution multispectral WorldView-2 imagery and Indicator Species Analysis  

NASA Astrophysics Data System (ADS)

Remote sensing technology has long been used in wetland inventory and monitoring though derived wetland maps were limited in applicability and often unsatisfactory largely due to the relatively coarse spatial resolution of conventional satellite imagery. The advent of high-resolution multispectral satellite systems presents new and exciting capabilities in mapping wetland systems with unprecedented accuracy and spatial detail. This research explores and evaluates the use of high-resolution WorldView-2 (WV2) multispectral imagery in identifying and classifying freshwater deltaic wetland vegetation and aquatic habitats in the Selenga River Delta, a Ramsar Wetland of International Importance that drains into Lake Baikal, Russia - a United Nations World Heritage site. A hybrid approach was designed and applied for WV2 image classification consisting of initial unsupervised classification, training data acquisition and analysis, indicator species analysis, and final supervised classification. A hierarchical scheme was defined and adopted for classifying aquatic habitats and wetland vegetation at genus and community levels at a fine scale, while at a coarser scale representing wetland systems as broad substrate and vegetation classes for regional comparisons under various existing wetland classification systems. Rigorous radiometric correction of WV2 images and orthorectification based on GPS-derived ground control points and an ASTER global digital elevation model resulted in 2- to 3-m positional accuracy. We achieved overall classification accuracy of 86.5% for 22 classes of wetland and aquatic habitats at the finest scale and >91% accuracy for broad vegetation and aquatic classes at more generalized scales. At the finest scale, the addition of four new WV2 spectral bands contributed to a classification accuracy increase of 3.5%. The coastal band of WV2 was found to increase the separation between different open water and aquatic habitats, while yellow, red-edge, and near-infrared 2 bands were more useful for discriminating between different vegetated habitats. Analyses demonstrated that the Normalized Difference Vegetation Index was valuable for improving the classification accuracy and image texture was particularly useful for separating scrub/shrub wetland from various emergent herbaceous wetlands. Our analysis resulted in the first-ever detailed, quantitative wetland inventory map of the Selenga River Delta, and provides a benchmark for future wetland change detection studies and baseline information for wetland conservation and management efforts for this region.

Lane, C.; Liu, H.; Anenkhonov, O.; Autrey, B.; Chepinoga, V.

2012-12-01

273

Cyanobacterial Toxins as Allelochemicals with Potential Applications as Algaecides, Herbicides and Insecticides  

PubMed Central

Cyanobacteria (“blue-green algae”) from marine and freshwater habitats are known to produce a diverse array of toxic or otherwise bioactive metabolites. However, the functional role of the vast majority of these compounds, particularly in terms of the physiology and ecology of the cyanobacteria that produce them, remains largely unknown. A limited number of studies have suggested that some of the compounds may have ecological roles as allelochemicals, specifically including compounds that may inhibit competing sympatric macrophytes, algae and microbes. These allelochemicals may also play a role in defense against potential predators and grazers, particularly aquatic invertebrates and their larvae. This review will discuss the existing evidence for the allelochemical roles of cyanobacterial toxins, as well as the potential for development and application of these compounds as algaecides, herbicides and insecticides, and specifically present relevant results from investigations into toxins of cyanobacteria from the Florida Everglades and associated waterways. PMID:18728763

Berry, John P.; Gantar, Miroslav; Perez, Mario H.; Berry, Gerald; Noriega, Fernando G.

2008-01-01

274

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

Microsoft Academic Search

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

Nicole Sonntag; Stefan Garthe; Sven Adler

2009-01-01

275

Species Composition and Inter-annual Dynamics of a Freshwater Tidal Plant Community Following Removal of the Invasive Grass, Phragmites australis  

Microsoft Academic Search

We document the regeneration of native freshwater wetland plant assemblages following removal of the common reed, Phragmites australis (Cav.) Trin. ex Steudel from two sites at Chapman Pond, East Haddam, Connecticut, USA. We gathered field data on composition of the vegetation 1 year before and for each of the 3 years after the removal in fall 1995\\/spring 1996 of Phragmites

Elizabeth J. Farnsworth; Laura A. Meyerson

1999-01-01

276

Species composition and inter-annual dynamics of a freshwater tidal plant community following removal of the invasive grass, Phragmites australis  

Microsoft Academic Search

We document the regeneration of native freshwater wetland plant assemblages following removal of the common reed, Phragmites australis (Cav.) Trin. ex Steudel from two sites at Chapman Pond, East Haddam, Connecticut, USA. We gathered field data on composition of the vegetation 1 year before and for each of the 3 years after the removal in fall 1995\\/spring 1996 of Phragmites

Elizabeth J. Farnsworth; Laura A. Meyerson

1999-01-01

277

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. PMID:15814353

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

2005-01-01

278

Effects of growth conditions on the production of neurotoxin 2,4-diaminobutyric acid (DAB) in Microcystis aeruginosa and its universal presence in diverse cyanobacteria isolated from freshwater in China.  

PubMed

Neurotoxins ?-N-methylamino-L-alanine (BMAA) and its isomer 2,4-diaminobutyric acid (DAB) have been reported previously in diverse strains of cyanobacteria. In this study, BMAA and DAB were analyzed for two strains of Microcystis aeruginosa incubated with four different levels of phosphate, nitrate, illumination, and temperature, respectively, in order to explore the effects of growth factors on toxin-producing ability of cyanobacteria. Both toxins were also screened in 17 cyanobacterial strains cultured with BG-11 medium and conventional illumination and temperature conditions, and in three field phytoplankton samples collected from different lakes in China. All samples were analyzed using a liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) system coupled with a hydrophilic interaction liquid chromatography (HILIC) column. Results showed that no BMAA was detected in any of the cyanobacterial strains grown under our laboratory culture conditions, or in any of the field samples. Production of DAB in M. aeruginosa was significantly enhanced by extreme concentrations of nutrient and physical factors. Various concentrations of DAB were also present in most cultured samples (13 of 17) of cyanobacteria and were not species specific. This is the first time to report the production of DAB in M. aeruginosa cultured under alterative conditions in laboratory. Occurrence of DAB in most of the strains examined here means that consideration should be given to the presence of this compound in freshwater environment in China. PMID:25354443

Fan, Hua; Qiu, Jiangbing; Fan, Lin; Li, Aifeng

2015-04-01

279

Distribution of the freshwater fishes of Japan: an historical overview  

Microsoft Academic Search

Japanese freshwater fishes, including lampreys, comprise 15 orders, 35 families, and 96 genera, with 211 species and subspecies. Most belong to the families Cyprinidae (29% of species and subspecies), Gobiidae (21%), Salmonidae (10%), and Cobitidae (8%). Cyprinids and cobitids presumably originated from east Asia, gobiids from southeast Asia, and cottids and salmonids from the north Pacific. Japanese freshwater fishes include

Masahide Yuma; Kazumi Hosoya; Yoshikazu Nagata

1998-01-01

280

FRESHWATER FISHES OF ALASKA: THEIR BIOLOGY, DISTRIBUTION AND VALUE  

EPA Science Inventory

A summary of knowledge of the freshwater fishes of Alaska is provided. Covered are 56 species in 34 genera and 15 families, including strictly freshwater species, anadromous forms and those which normally are marine but which occasionally or regularly enter fresh water. For each ...

281

Technical challenges in metatranscriptomic studies applied to the bacterial communities of freshwater ecosystems.  

PubMed

Metatranscriptome analysis relates to the transcriptome of microbial communities directly sampled in the environment. Accessing the mRNA pool in natural bacterial communities presents some technical challenges such as the RNA extraction, rRNA depletion, and the choice of the high-throughput sequencing technique. The lack of technical details in scientific articles is a major problem to correctly obtained mRNA from a microbial community and thus the corresponding sequencing data. In our study, we present the methodological procedure that was developed in order to access to the metatranscriptome of the microbial communities during two cyanobacterial blooms successively occurring in a freshwater eutrophic lake. Each procedure step was detailed and discussed with regard to the choices and difficulties encountered and to the recent literature. Finally, the two major limits for metatranscriptomic approaches targeting bacterial communities from natural environments were (i) the removal of rRNA in order to increase the putative mRNA reads number after sequencing, and (ii) for most of the bacterial communities living in natural environments, the lack of reference genomes in databases that leads to the non-assignation of numerous reads. Once these challenges overcome, we managed to access putative mRNA of dominant species, i.e. cyanobacteria (from 6 to 72 % of mRNA assigned), and of the surrounding bacteria (from 1 to 5 % of mRNA assigned). PMID:25216965

Pascault, Noémie; Loux, Valentin; Derozier, Sandra; Martin, Véronique; Debroas, Didier; Maloufi, Selma; Humbert, Jean-François; Leloup, Julie

2015-04-01

282

Gill Reaction to Pollutants from the Tamiš River in Three Freshwater Fish Species, Esox lucius L. 1758, Sander lucioperca (L. 1758) and Silurus glanis L. 1758: A Comparative Study.  

PubMed

The study evaluated the effects of waterborne pollutants from the Tamiš River on gill histology and possible differences in gill reaction patterns between three freshwater fish species, pike Esox lucius L. 1758, pike-perch Sander lucioperca (L. 1758) and wels catfish Silurus glanis L. 1758 from the Tamiš River. Gills from analysed fish species showed moderate to intense histopathological alterations. The most frequent progressive alteration was hyperplasia of epithelium, whereas the most frequent regressive alteration was epithelial lifting. Circulatory disturbances were most often manifested in the form of hyperaemia. During comparative analysis, differences in gill indices, reaction and alteration indices, as well as in gill and filament prevalence between analysed species, were observed. Although all analysed fish species did show both progressive and regressive alterations, there was a significant difference in the level of expression of these reaction patterns. Gill index obtained for pike clearly stands out as the lowest. Wels catfish showed the highest progressive reaction index, significantly higher in comparison with the other two species (P < 0.05), while pike-perch showed the highest regressive reaction index, also significantly higher in comparison with the other species (P < 0.001). These results may implicate species-specific gill reactions and thus present a useful tool for better understanding toxic mechanisms of various pollutants. PMID:24809962

Luji?, J; Matavulj, M; Poleksi?, V; Raškovi?, B; Marinovi?, Z; Kosti?, D; Miljanovi?, B

2015-04-01

283

Seasnake bites in a freshwater lake.  

PubMed

One species of venomous seasnake, Hydrophis semperi, is found in Lake Taal, a large freshwater lake in the Philippines. The first series of seasnake bites occurring in freshwater is described. In one small fishing village, there were eight definite bites and one probably attributable death. In three of the eight patients, specific antibodies to Hydrophis venom were demonstrated. In contrast to previous seasnake studies, there was an absence of asymptomatic cases. The possible public health importance of freshwater seasnake bites in the Philippines needs further investigation. PMID:4025692

Watt, G; Theakston, R D

1985-07-01

284

Direct use of low temperature geothermal water by Aquafarms International, Inc. for freshwater aquaculture (prawns and associated species). An operations and maintenance manual  

SciTech Connect

In connection with an ongoing commercial aquaculture project in the Coachella Valley, California; a twelve month prawn growout demonstration project was conducted. This project began in August, 1979 and involved the use of low temperature (85/sup 0/F) geothermal waters to raise freshwater prawns, Macrobrachium rosenbergii (deMan), in earthen ponds. The following publication is an operations and maintenance guide which may by useful for those interested in conducting similar enterprises.

Broughton, R.; Price, M.; Price, V.; Grajcer, D.

1984-04-01

285

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

2008-01-01

286

Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples.  

PubMed

Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a survey on cyanobacterial blooms and studied three ponds in detail. Among 3,500 urban ponds in the urbanized Dutch province of North Brabant, 125 showed cyanobacterial blooms in the period 2009-2012. This covered 79% of all locations registered for cyanobacterial blooms, despite the fact that urban ponds comprise only 11% of the area of surface water in North Brabant. Dominant bloom-forming genera in urban ponds were Microcystis, Anabaena and Planktothrix. In the three ponds selected for further study, the microcystin concentration of the water peaked at 77 ?g l(-1) and in scums at 64,000 ?g l(-1), which is considered highly toxic. Microcystin-RR and microcystin-LR were the most prevalent variants in these waters and in scums. Cyanobacterial chlorophyll-a peaked in August with concentrations up to 962 ?g l(-1) outside of scums. The ponds were highly eutrophic with mean total phosphorus concentrations between 0.16 and 0.44 mg l(-1), and the sediments were rich in potential releasable phosphorus. High fish stocks dominated by carp lead to bioturbation, which also favours blooms. As urban ponds in North Brabant, and likely in other regions, regularly suffer from cyanobacterial blooms and citizens may easily have contact with the water and may ingest cyanobacterial material during recreational activities, particularly swimming, control of health risk is of importance. Monitoring of cyanobacteria and cyanobacterial toxins in urban ponds is a first step to control health risks. Mitigation strategies should focus on external sources of eutrophication and consider the effect of sediment P release and bioturbation by fish. PMID:24798921

Waajen, Guido W A M; Faassen, Elisabeth J; Lürling, Miquel

2014-08-01

287

International Freshwater Agreements  

E-print Network

and the Food and Agriculture Organization of the United Nations. "The World's International Freshwater Variability and Shared Benefits" was authored by Aaron T. Wolf. Transboundary Freshwater Dispute Database Variability and Shared Benefits ................................................... 9 Number of Agreements per

Wolf, Aaron

288

A natural view of microbial biodiversity within hot spring cyanobacterial mat communities.  

PubMed

This review summarizes a decade of research in which we have used molecular methods, in conjunction with more traditional approaches, to study hot spring cyanobacterial mats as models for understanding principles of microbial community ecology. Molecular methods reveal that the composition of these communities is grossly oversimplified by microscopic and cultivation methods. For example, none of 31 unique 16S rRNA sequences detected in the Octopus Spring mat, Yellowstone National Park, matches that of any prokaryote previously cultivated from geothermal systems; 11 are contributed by genetically diverse cyanobacteria, even though a single cyanobacterial species was suspected based on morphologic and culture analysis. By studying the basis for the incongruity between culture and molecular samplings of community composition, we are beginning to cultivate isolates whose 16S rRNA sequences are readily detected. By placing the genetic diversity detected in context with the well-defined natural environmental gradients typical of hot spring mat systems, the relationship between gene and species diversity is clarified and ecological patterns of species occurrence emerge. By combining these ecological patterns with the evolutionary patterns inherently revealed by phylogenetic analysis of gene sequence data, we find that it may be possible to understand microbial biodiversity within these systems by using principles similar to those developed by evolutionary ecologists to understand biodiversity of larger species. We hope that such an approach guides microbial ecologists to a more realistic and predictive understanding of microbial species occurrence and responsiveness in both natural and disturbed habitats. PMID:9841675

Ward, D M; Ferris, M J; Nold, S C; Bateson, M M

1998-12-01

289

A natural view of microbial biodiversity within hot spring cyanobacterial mat communities  

NASA Technical Reports Server (NTRS)

This review summarizes a decade of research in which we have used molecular methods, in conjunction with more traditional approaches, to study hot spring cyanobacterial mats as models for understanding principles of microbial community ecology. Molecular methods reveal that the composition of these communities is grossly oversimplified by microscopic and cultivation methods. For example, none of 31 unique 16S rRNA sequences detected in the Octopus Spring mat, Yellowstone National Park, matches that of any prokaryote previously cultivated from geothermal systems; 11 are contributed by genetically diverse cyanobacteria, even though a single cyanobacterial species was suspected based on morphologic and culture analysis. By studying the basis for the incongruity between culture and molecular samplings of community composition, we are beginning to cultivate isolates whose 16S rRNA sequences are readily detected. By placing the genetic diversity detected in context with the well-defined natural environmental gradients typical of hot spring mat systems, the relationship between gene and species diversity is clarified and ecological patterns of species occurrence emerge. By combining these ecological patterns with the evolutionary patterns inherently revealed by phylogenetic analysis of gene sequence data, we find that it may be possible to understand microbial biodiversity within these systems by using principles similar to those developed by evolutionary ecologists to understand biodiversity of larger species. We hope that such an approach guides microbial ecologists to a more realistic and predictive understanding of microbial species occurrence and responsiveness in both natural and disturbed habitats.

Ward, D. M.; Ferris, M. J.; Nold, S. C.; Bateson, M. M.

1998-01-01

290

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).  

PubMed

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

2012-06-15

291

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

PubMed

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

2012-06-01

292

DNA barcoding of freshwater fishes and the development of a quantitative qPCR assay for the species-specific detection and quantification of fish larvae from plankton samples.  

PubMed

The barcoding of mitochondrial cytochrome c oxidase subunit 1 (coI) gene was amplified and sequenced from 16 species of freshwater fishes found in Lake Wivenhoe (south-eastern Queensland, Australia) to support monitoring of reservoir fish populations, ecosystem function and water health. In this study, 630-650 bp sequences of the coI barcoding gene from 100 specimens representing 15 genera, 13 families and two subclasses of fishes allowed 14 of the 16 species to be identified and differentiated. The mean ± s.e. Kimura 2 parameter divergence within and between species was 0.52 ± 0.10 and 23.8 ± 2.20% respectively, indicating that barcodes can be used to discriminate most of the fish species accurately. The two terapontids, Amniataba percoides and Leiopotherapon unicolor, however, shared coI DNA sequences and could not be differentiated using this gene. A barcoding database was established and a qPCR assay was developed using coI sequences to identify and quantify proportional abundances of fish species in ichthyoplankton samples from Lake Wivenhoe. These methods provide a viable alternative to the time-consuming process of manually enumerating and identifying ichthyoplankton samples. PMID:24963726

Loh, W K W; Bond, P; Ashton, K J; Roberts, D T; Tibbetts, I R

2014-08-01

293

DEVELOPMENT OF A HUMAN BIOMARKER FOR CYANOBACTERIAL TOXINS-MICROCYSTINS  

EPA Science Inventory

This study will determine if a commercially- available enzyme linked immunosorbant assay (ELISA) designed to detect microcystins in water can be used to detect microcystins in human serum and liver. Increasingly, cyanobacterial blooms are being reported worldwide due to several...

294

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. PMID:22412816

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

2012-01-01

295

Association of a new type of gliding, filamentous, purple phototrophic bacterium inside bundles of Microcoleus chthonoplastes in hypersaline cyanobacterial mats  

NASA Technical Reports Server (NTRS)

An unidentified filamentous purple bacterium, probably belonging to a new genus or even a new family, is found in close association with the filamentous, mat-forming cyanobacterium Microcoleus chthonoplastes in a hypersaline pond at Guerrero Negro, Baja California Sur, Mexico, and in Solar Lake, Sinai, Egypt. This organism is a gliding, segmented trichome, 0.8-0.9 micrometer wide. It contains intracytoplasmic stacked lamellae which are perpendicular and obliquely oriented to the cell wall, similar to those described for the purple sulfur bacteria Ectothiorhodospira. These bacteria are found inside the cyanobacterial bundle, enclosed by the cyanobacterial sheath. Detailed transmission electron microscopical analyses carried out in horizontal sections of the upper 1.5 mm of the cyanobacterial mat show this cyanobacterial-purple bacterial association at depths of 300-1200 micrometers, corresponding to the zone below that of maximal oxygenic photosynthesis. Sharp gradients of oxygen and sulfide are established during the day at this microzone in the two cyanobacterial mats studied. The close association, the distribution pattern of this association and preliminary physiological experiments suggest a co-metabolism of sulfur by the two-membered community. This probable new genus of purple bacteria may also grow photoheterotrophically using organic carbon excreted by the cyanobacterium. Since the chemical gradients in the entire photic zone fluctuate widely in a diurnal cycle, both types of metabolism probably take place. During the morning and afternoon, sulfide migrates up to the photic zone allowing photoautotrophic metabolism with sulfide as the electron donor. During the day the photic zone is highly oxygenated and the purple bacteria may either use oxidized species of sulfur such as elemental sulfur and thiosulfate in the photoautotrophic mode or grow photoheterotrophically using organic carbon excreted by M. chthonoplastes. The new type of filamentous purple sulfur bacteria is not available yet in pure culture, and its taxonomical position cannot be fully established. This organism is suggested to be a new type of gliding, filamentous, purple phototroph.

D'Amelio, E. D.; Cohen, Y.; Des Marais, D. J.

1987-01-01

296

The Languages Spoken in the Water Body (or the Biological Role of Cyanobacterial Toxins)  

PubMed Central

Although intensification of toxic cyanobacterial blooms over the last decade is a matter of growing concern due to bloom impact on water quality, the biological role of most of the toxins produced is not known. In this critical review we focus primarily on the biological role of two toxins, microcystins and cylindrospermopsin, in inter- and intra-species communication and in nutrient acquisition. We examine the experimental evidence supporting some of the dogmas in the field and raise several open questions to be dealt with in future research. We do not discuss the health and environmental implications of toxin presence in the water body. PMID:22529842

Kaplan, Aaron; Harel, Moshe; Kaplan-Levy, Ruth N.; Hadas, Ora; Sukenik, Assaf; Dittmann, Elke

2012-01-01

297

Lake Level Fluctuations Boost Toxic Cyanobacterial “Oligotrophic Blooms”  

PubMed Central

Global warming has been shown to strongly influence inland water systems, producing noticeable increases in water temperatures. Rising temperatures, especially when combined with widespread nutrient pollution, directly favour the growth of toxic cyanobacteria. Climate changes have also altered natural water level fluctuations increasing the probability of extreme events as dry periods followed by heavy rains. The massive appearance of Dolichospermum lemmermannii (?=?planktonic Anabaena), a toxic species absent from the pelagic zone of the subalpine oligotrophic Lake Maggiore before 2005, could be a consequence of the unusual fluctuations of lake level in recent years. We hypothesized that these fluctuations may favour the cyanobacterium as result of nutrient pulses from the biofilms formed in the littoral zone when the lake level is high. To help verify this, we exposed artificial substrates in the lake, and evaluated their nutrient enrichment and release after desiccation, together with measurements of fluctuations in lake level, precipitation and D.lemmermannii population. The highest percentage of P release and the lowest C?P molar ratio of released nutrients coincided with the summer appearance of the D.lemmermannii bloom. The P pulse indicates that fluctuations in level counteract nutrient limitation in this lake and it is suggested that this may apply more widely to other oligotrophic lakes. In view of the predicted increase in water level fluctuations due to climate change, it is important to try to minimize such fluctuations in order to mitigate the occurrence of cyanobacterial blooms. PMID:25295866

Callieri, Cristiana; Bertoni, Roberto; Contesini, Mario; Bertoni, Filippo

2014-01-01

298

Photocatalytic degradation of cyanobacterial microcystin toxins in water.  

PubMed

The microcystins are hepatotoxins produced by a number of cyanobacterial species (blue green algae) in fresh water systems. The increasing eutrophication of natural waters has led to an increase in the incidence of algal blooms and the consequent increased risk of microcystin contamination of water resources. The removal of microcystins LR, YR and YA from contaminated water was investigated using an experimental laboratory-scale photocatalytic 'falling film' reactor in which an oxygen purge, UV radiation and semiconductor titanium dioxide (TiO2) catalyst were used to oxidatively decompose the microcystin pollutants. Preliminary studies, using algal extracts spiked into distilled water, indicated that the microcystins were rapidly decomposed in this reactor. The decomposition followed first order reaction kinetics with half-lives of less than 5 min with the reactor operating in a closed-loop mode. Reaction rates were strongly dependent on the amount of TiO2 catalyst (O-5 g/l), but only marginally influenced by a change in gas purge from oxygen to compressed air. The use of lake water, rather than distilled water, showed that this process is feasible in natural waters, although increased levels of catalyst (up to 5 g/l) were required to achieve comparable decomposition rates. PMID:9839673

Shephard, G S; Stockenström, S; De Villiers, D; Engelbrecht, W J; Sydenham, E W; Wessels, G F

1998-12-01

299

A Comparison of Freshwater Macroinvertebrate Communities on Small Caribbean Islands  

NSDL National Science Digital Library

This peer-reviewed article from BioScience is about freshwater macroinvetebrate communities. An ongoing survey of macroinvertebrates inhabiting the relatively unstudied freshwater habitats on 14 small Caribbean islands was initiated in 1991. These collections have yielded almost 200 species; when these species are combined with collections previously made by other researchers, a total of at least 328 freshwater macroinvertebrates are now known from these islands. The dominant taxa on the islands include several species of snails, shrimps, mayflies, dragonflies, damselflies, beetles, and other insects. Many of these species have fairly widespread distributions across the islands. Most stream species are associated with leaf packs, and most pond species are associated with aquatic macrophytes. As is typical of tropical island systems, the macroinvertebrate faunas of these islands are sparse, most likely because of their oceanic origin, their small size, and the frequent disturbances to their freshwater environments.

DAVID BASS (; )

2003-11-01

300

Flavodiiron proteins Flv1 and Flv3 enable cyanobacterial growth and photosynthesis under fluctuating light  

PubMed Central

Cyanobacterial flavodiiron proteins (FDPs; A-type flavoprotein, Flv) comprise, besides the ?-lactamase–like and flavodoxin domains typical for all FDPs, an extra NAD(P)H:flavin oxidoreductase module and thus differ from FDPs in other Bacteria and Archaea. Synechocystis sp. PCC 6803 has four genes encoding the FDPs. Flv1 and Flv3 function as an NAD(P)H:oxygen oxidoreductase, donating electrons directly to O2 without production of reactive oxygen species. Here we show that the Flv1 and Flv3 proteins are crucial for cyanobacteria under fluctuating light, a typical light condition in aquatic environments. Under constant-light conditions, regardless of light intensity, the Flv1 and Flv3 proteins are dispensable. In contrast, under fluctuating light conditions, the growth and photosynthesis of the ?flv1(A) and/or ?flv3(A) mutants of Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120 become arrested, resulting in cell death in the most severe cases. This reaction is mainly caused by malfunction of photosystem I and oxidative damage induced by reactive oxygen species generated during abrupt short-term increases in light intensity. Unlike higher plants that lack the FDPs and use the Proton Gradient Regulation 5 to safeguard photosystem I, the cyanobacterial homolog of Proton Gradient Regulation 5 is shown not to be crucial for growth under fluctuating light. Instead, the unique Flv1/Flv3 heterodimer maintains the redox balance of the electron transfer chain in cyanobacteria and provides protection for photosystem I under fluctuating growth light. Evolution of unique cyanobacterial FDPs is discussed as a prerequisite for the development of oxygenic photosynthesis. PMID:23431195

Allahverdiyeva, Yagut; Mustila, Henna; Ermakova, Maria; Bersanini, Luca; Richaud, Pierre; Ajlani, Ghada; Battchikova, Natalia; Cournac, Laurent; Aro, Eva-Mari

2013-01-01

301

Young Freshwater Mussels as seen Through a Microscope  

USGS Multimedia Gallery

During laboratory tests, USGS Upper Midwest Environmental Sciences Center scientists and partners found that the heart and growth rates of some species of young freshwater mussels declined as a result of elevated water temperatures, and many died. Freshwater mussels have been compared to the “...

302

A Review of Cyanobacterial Odorous and Bioactive Metabolites: Impacts and Management Alternatives in Aquaculture  

Technology Transfer Automated Retrieval System (TEKTRAN)

An increased demand has pushed extensive aquaculture towards intensively operated production systems, commonly resulting in eutrophic conditions and cyanobacterial blooms. This review summarizes cyanobacterial secondary metabolites that can cause undesirable tastes and odors (odorous metabolites) o...

303

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

304

Hydrogen isotope fractionation in freshwater and marine algae: II. Temperature and nitrogen limited growth rate effects  

E-print Network

Hydrogen isotope fractionation in freshwater and marine algae: II. Temperature and nitrogen limited isotope fractionation in freshwater algae: I. Variations among lipids and spe- cies. Organic Geochemistry. Two species of freshwater green algae, Eudorina unicocca and Volvox aureus, were grown in batch

Sachs, Julian P.

305

The cyanobacterial genome core and the origin of photosynthesis Robert Haselkorn, and Michael Y. Galperin  

E-print Network

that photosynthesis originated in the cyanobacterial lineage under the selective pressures of UV light and depletionThe cyanobacterial genome core and the origin of photosynthesis Robert Haselkorn, and Michael Y.pnas.org/misc/reprints.shtml To order reprints, see: Notes: #12;The cyanobacterial genome core and the origin of photosynthesis Armen Y

Steinhoff, Heinz-Jürgen

306

Prevalence of chemical defenses among freshwater plants.  

PubMed

Although macrophyte herbivore interactions in freshwater systems were generally disregarded for many years, recent data suggest that herbivory can be intense and important in structuring freshwater communities. This has led to the hypothesis that chemical defenses should be common among freshwater plants, but few studies have reported such chemical defenses, and no previous studies have assessed the frequency of chemical defenses among a substantial number of freshwater plant species. In a study of 21 macrophyte species co-occurring with the omnivorous crayfish Procambarus acutus in a southeastern USA wetland environment, we found that extracts of 11 species (52%) deterred feeding by P. acutus when tested in artificial foods at natural concentrations. Of these 11 chemically defended species, one species, Eupatorium capillifolium, consistently had a more unpalatable extract following mechanical damage to plant tissue, indicative of an activated chemical defense. Because herbivores are commonly nitrogen-limited and select food based on several plant traits, including plant nutritional value, it might be expected that chemical defenses would be especially important for protein-rich plants. However, we found no relationship between soluble protein concentration and deterrence of plant extracts. PMID:16124238

Prusak, Anne C; O'Neal, Jennifer; Kubanek, Julia

2005-05-01

307

Cyanobacterial diversity and a new acaryochloris-like symbiont from Bahamian sea-squirts.  

PubMed

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. PMID:21915246

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

2011-01-01

308

Climate change: a catalyst for global expansion of harmful cyanobacterial blooms.  

PubMed

Cyanobacteria are the Earth's oldest known oxygen-evolving photosynthetic microorganisms, and they have had major impacts on shaping our current atmosphere and biosphere. Their long evolutionary history has enabled cyanobacteria to develop survival strategies and persist as important primary producers during numerous geochemical and climatic changes that have taken place on Earth during the past 3.5 billion years. Today, some cyanobacterial species form massive surface growths or 'blooms' that produce toxins, cause oxygen depletion and alter food webs, posing a major threat to drinking and irrigation water supplies, fishing and recreational use of surface waters worldwide. These harmful cyanobacteria can take advantage of anthropogenically induced nutrient over-enrichment (eutrophication), and hydrologic modifications (water withdrawal, reservoir construction). Here, we review recent studies revealing that regional and global climatic change may benefit various species of harmful cyanobacteria by increasing their growth rates, dominance, persistence, geographic distributions and activity. Future climatic change scenarios predict rising temperatures, enhanced vertical stratification of aquatic ecosystems, and alterations in seasonal and interannual weather patterns (including droughts, storms, floods); these changes all favour harmful cyanobacterial blooms in eutrophic waters. Therefore, current mitigation and water management strategies, which are largely based on nutrient input and hydrologic controls, must also accommodate the environmental effects of global warming. PMID:23765717

Paerl, Hans W; Huisman, Jef

2009-02-01

309

Limnology and cyanobacterial diversity of high altitude lakes of Lahaul-Spiti in Himachal Pradesh, India.  

PubMed

Limnological data of four high altitude lakes from the cold desert region of Himachal Pradesh, India, has been correlated with cyanobacterial diversity. Physico-chemical characteristics and nutrient contents of the studied lakes revealed that Sissu Lake is mesotrophic while Chandra Tal, Suraj Tal and Deepak Tal are ultra-oligotrophic. Based on morphology and 16S rRNA gene sequence, a total of 20 cyanobacterial species belonging to 11 genera were identified. Canonical correspondence analysis distinguished three groups of species with respect to their occurrence and nutrient/physical environment demand. The first group, which included Nostoc linckia, N. punctiforme, Nodularia sphaerocarpa, Geitlerinema acutissimum, Limnothrix redekii, Planktothrix agardhii and Plank. clathrata, was characteristic of water with high nutrient content and high temperature. The second group, including Gloeocapsopsis pleurocapsoides, Leptolyngbya antarctica, L. frigida, Pseudanabaena frigida and N. spongiaeforme, occurred in oligotrophic water with high pH and low temperature. The distribution of third group of Cyanobium parvum, Synechocystis pevalekii, L. benthonica, L. foveolarum, L. lurida, L. valderiana, Phormidium autumnale and P. chalybeum could not be associated with a particular environmental condition because of their presence in all sampling sites. PMID:25116619

Singh, Y; Khattar, Jis; Singh, D P; Rahi, P; Gulati, A

2014-09-01

310

Tests for the toxicity assessment of cyanobacterial bloom samples.  

PubMed

Cyanobacterial (blue-green algal) blooms are one of the common consequences of the increasing eutrophication of surface waters. The production of cyanobacterial toxins and their presence in drinking and recreational waters represents a growing danger to human and animal health. Due to a lack of toxin standards and to resource limitations on the wide-scale use of analytical methods (e.g., high-performance liquid chromatography, enzyme-linked immunosorbent assay (ELISA)) in cyanobacterial toxin monitoring, it is necessary to assess and to develop additional methods for their detection and estimation. Microbiotests using invertebrates offer a possible approach for the inexpensive and straightforward detection and assessment of cyanobacterial bloom toxicity. Three microbiotests with: Thamnocephalus platyurus, Daphnia magna, and Spirostomum ambiguum were examined with bloom samples containing hepatotoxic microcystin-LR and up to five additional microcystin variants. Two kinds of cyanobacterial bloom sample preparations were tested: crude extracts (CE) and purified extracts (PE). The highest toxicity was found when CE was used for microbiotests. The sensitivity of microorganisms decreased from S. ambiguum to T. platyurus and to D. magna. A statistically significant correlation was found between microcystin concentration and T. platyurus biotest, and between mouse bioassay and S. ambiguum results. Addition of Me2SO (1%, v/v) is a possible method to increase the sensitivity of the microorganisms for microcystin-LR. PMID:11594024

Tarczynska, M; Nalecz-Jawecki, G; Romanowska-Duda, Z; Sawicki, J; Beattie, K; Codd, G; Zalewski, M

2001-10-01

311

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

PubMed

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

2011-11-01

312

Variation of microcystins, cyanobacterial hepatotoxins, in Anabaena spp. as a function of growth stimuli.  

PubMed

Cyanobacterial hepatotoxins, microcystins, are specific inhibitors of serine/threonine protein phosphatases and potent tumor promoters. They have caused several poisonings of animals and also pose a health hazard for humans through the use of water for drinking and recreation. Different strains of the same cyanobacterial species may variously be nontoxic, be neurotoxic, or produce several microcystin variants. It is poorly understood how the amount of toxins varies in a single strain. This laboratory study shows the importance of external growth stimuli in regulating the levels and relative proportions of different microcystin variants in two strains of filamentous, nitrogen-fixing Anabaena spp. The concentration of the toxins in the cells increased with phosphorus. High temperatures (25 to 30 degrees C), together with the highest levels of light studied (test range, 2 to 100 mumol m-2 s-1), decreased their amount. Different structural variants of microcystins responded differently to growth stimuli. Variants of microcystin (MCYST)-LR correlated with temperatures below 25 degrees C, and those of MCYST-RR correlated with higher temperatures. Nitrogen added into the growth medium and increasing temperatures increased the proportion of microcystin variants demethylated in amino acid 3. All variants remained mostly intracellular. Time was the most important factor causing the release of the toxins into the growth medium. Time, nitrogen added into the growth medium, and light fluxes above 25 mumol m-2 s-1 significantly increased the concentrations of the dissolved toxins. According to the results, it thus seems that the reduction of phosphorus loads in bodies of water might play a role in preventing the health hazards that toxic cyanobacterial water blooms pose, not only by decreasing the cyanobacteria but also by decreasing their toxin content. PMID:9172340

Rapala, J; Sivonen, K; Lyra, C; Niemelä, S I

1997-06-01

313

DISPERSAL IN FRESHWATER INVERTEBRATES  

Microsoft Academic Search

? Abstract Movement between discrete habitat patches can present significant challenges to organisms. Freshwater invertebrates achieve dispersal using a variety of mechanisms that can be broadly categorized as active or passive, and which have important consequences for processes of colonization, gene flow, and evolutionary divergence. Apart from flight in adult freshwater insects, active dispersal appears rela- tively uncommon. Passive dispersal

David T. Bilton; Joanna R. Freeland; Beth Okamura

2001-01-01

314

TOXICITY AND METABOLISM STUDIES WITH EPA (ENVIRONMENTAL PROTECTION AGENCY) PRIORITY POLLUTANTS AND RELATED CHEMICALS IN FRESHWATER ORGANISMS  

EPA Science Inventory

Twenty-two chemicals from the EPA priority pollutant list were studied for their acute and/or chronic toxicity to selected freshwater organisms. Freshwater species tested included the fathead minnow (Pimephales promelas), rainbow trout (Salmo gairdneri), bluegill sunfish (Lepomis...

315

AVES.NET: The Freshwater Dinoflagellates  

NSDL National Science Digital Library

Hosted by AVES.NET, this website about Freshwater Dinoflagellates was created by Victor W. Fazio III and Dr. Susan Carty of Heidelberg College (Tiffin, Ohio). Two main attractions of this site are the Freshwater Dinoflagellate Image Archive, and the Recent Additions-Freshwater Dinoflagellate Images 2003 (from the 2003-04 winter field season). Individual Dinoflagellate image pages generally include a ventral view, dorsal view, or both, and the pages featuring species from Ohio include county distribution maps. Site visitors can email Dr. Carty for permission to use any of the images. The website also contains a List of Freshwater Dinoflagellates in Ohio, some of which link to the individual image pages. Additionally, the site offers a Review of Online Images of Freshwater Dinoflagellates including links to many other host sites, and a link to an online article by Dr. Susan Carty and Daniel E. Wujek entitled _A New Species of Peridinium and New Records of Dinoflagellates and Silica-Scaled Chrysophytes from Belize._ [NL

Carty, Susan

316

Mechanics and Resonance of the Cyanobacterial Circadian Oscillator  

E-print Network

Recent experiments elucidated the structure and function of the cyanobacterial circadian oscillator, which is driven by sunlight intensity variation and therefore by Earth's rotation. It is known that cyanobacteria appeared about 3.5 billion years ago and that Earth's rotational speed is continuously decreasing because of tidal friction. What is the effect of the continuous slowdown of Earth's rotation on the operation of the cyanobacterial oscillator? To answer this question we derived the oscillator's equation of motion directly from experimental data, coupled it with Earth's rotation and computed its natural periods and its resonance curve. The results show that there are two resonance peaks of the "cyanobacterial oscillator-rotating Earth" system, indicating that cyanobacteria used more efficiently the solar energy during the geological period in which the day length varied from about 11 to 15 hours and make more efficient use of solar energy at the geological period which started with a day length of 21 ...

Karafyllidis, Ioannis G

2012-01-01

317

Hydrogen from Water in a Novel Recombinant Cyanobacterial System  

SciTech Connect

Photobiological processes are attractive routes to renewable H2 production. With the input of solar energy, photosynthetic microbes such as cyanobacteria and green algae carry out oxygenic photosynthesis, using sunlight energy to extract protons and high energy electrons from water. These protons and high energy electrons can be fed to a hydrogenase system yielding H2. However, most hydrogen-evolving hydrogenases are inhibited by O2, which is an inherent byproduct of oxygenic photosynthesis. The rate of H2 production is thus limited. Certain photosynthetic bacteria are reported to have an O2-tolerant evolving hydrogenase, yet these microbes do not split water, and require other more expensive feedstocks. To overcome these difficulties, the goal of this work has been to construct novel microbial hybrids by genetically transferring O2-tolerant hydrogenases from other bacteria into a class of photosynthetic bacteria called cyanobacteria. These hybrid organisms will use the photosynthetic machinery of the cyanobacterial hosts to perform the water-oxidation reaction with the input of solar energy, and couple the resulting protons and high energy electrons to the O2-tolerant bacterial hydrogenase, all within the same microbe (Fig. 1). The ultimate goal of this work has been to overcome the sensitivity of the hydrogenase enzyme to O2 and address one of the key technological hurdles to cost-effective photobiological H2 production which currently limits the production of hydrogen in algal systems. In pursuit of this goal, work on this project has successfully completed many subtasks leading to a greatly increased understanding of the complicated [NiFe]-hydrogenase enzymes. At the beginning of this project, [NiFe] hydrogenases had never been successfully moved across wide species barriers and had never been heterologously expressed in cyanobacteria. Furthermore, the idea that whole, functional genes could be extracted from complicated, mixed-sequence meta-genomes was not established. In the course of this work, we identified a new hydrogenase from environmental DNA sequence and successfully expressed it in a variety of hosts including cyanobacteria. This was one of the first examples of these complicated enzymes being moved across vastly different bacterial species and is the first example of a hydrogenase being “brought to life” from no other information than a DNA sequence from metagenomic data. The hydrogenase we identified had the molecular signature of other O2-tolerant hydrogenases, and we discovered that the resulting enzyme had exceptionally high oxygen- and thermo-tolerance. The new enzyme retained 80% of its activity after incubation at 80° C for 2 hours and retained 20% activity in 1% O2. We performed detailed analysis on the maturation genes required for construction of a functional enzyme of this class of hydrogenase, and found that seven additional maturation genes were required for minimal activity and a total of nine genes besides the hydrogenase were required for optimal maturation efficiency. Furthermore, we demonstrated that the maturation genes are functional on closely-related hydrogenase enzymes such as those from Alteromonas macleodii and Thiocapsa roseopersicina. Finally, we have extensively modified the hydrogenase to engineer new traits including higher H2 production and better interaction with electron donors. For example, combining two strategies increased hydrogenase activity in cyanobacteria by at least 20-fold over our initial expression level. The activity of this combined strain is almost twice that of the native hydrogenase activity in S. elongatus. This work validates the idea that these enzymes are broadly tolerant to modifications that may help integrate them into a successful photobiological H2 production system. While we did not achieve our ultimate goal of integrating the functional hydrogenase with the cyanobacterial photosynthetic apparatus, the work on this project has led to significant advances in the understanding of these complicated enzymes. This work will greatly benefit future

Weyman, Philip D [J. Craig Venter Institute; Smith, Hamillton O.

2014-12-03

318

FRESHWATER SNAILS (MOLLUSCA: GASTROPODA) OF NORTH AMERICA  

EPA Science Inventory

Freshwater gastropod mollusks are represented in North America (north of Mexico) by 15 families, 78 genera and, as treated in this manual, 499 species. They are grouped into two large subclasses, the gill-breathing, operculated Prosobranchia and the lung-breathing, non-operculate...

319

Freshwater Mollusks Survive Fish Gut Passage  

Microsoft Academic Search

Freshwater mollusks figure prominently in the diets of humpback whitefish (Coregonus pidschian) and broad whitefish (C. nasus), two benthic-feeding coregonid species. A recent examination of pea clams (Sphaeriidae), valve snails (Valvatidae), and pond snails (Lymnaeidae) from the lower digestive tracts of these fish found that many of the mollusks were alive. Survival completely through gut passage would indicate a dispersal

RANDY J. BROWN

320

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.

2006-12-01

321

A Sensitive Determination of Iodine Species, Including Organoiodine, for Freshwater and Seawater Samples Using High Performance Liquid Chromatography and Spectrophotometric Detection  

E-print Network

In order to more effectively use iodine isotope ratios, 129I/127I, as hydrological and geochemical tracers in aquatic systems, a new HPLC method was developed for the determination of iodine speciation. The dissolved iodine species that dominate...

Schwehr, K. A.; Santschi, P. H.

322

ELEVATED TEMPERATURE AND LAND USE FLOOD FREQUENCY ALTERATION EFFECTS ON RATES OF INVASIVE AND NATIVE SPECIES INTERACTIONS IN FRESHWATER FLOODPLAIN WETLANDS  

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...

323

Ethanol production from carbon dioxide using cyanobacterial biomass  

SciTech Connect

An ethanol production system, which consists of chemical and biochemical reaction processes for (1) biomass production using cyanobacterium Synechococcus leopoliensis through photosynthetic CO{sub 2} fixation, (2) glucose extraction from that biomass, and (3) ethanol fermentation from the extracted glucose using yeast Saccharomyces sake, was conceptually developed. S. sake was grown on the medium containing the cyanobacterial biomass extract and that containing reagent glucose. It was found that the specific rates of cell growth, glucose consumption, ethanol production and the yeast ethanol tolerance were enhanced by the addition of cyanobacterial biomass extract. 4 refs., 5 figs., 1 tab.

Mustaqim, Dani; Ohtaguchi, Kazuhisa [Tokyo Inst. of Technology (Japan)

1996-12-31

324

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. PMID:22690165

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

2012-01-01

325

Cyanobacterial bloom management through integrated monitoring and forecasting in large shallow eutrophic Lake Taihu (China).  

PubMed

The large shallow eutrophic Lake Taihu in China has long suffered from eutrophication and toxic cyanobacterial blooms. Despite considerable efforts to divert effluents from the watershed, the cyanobacterial blooms still reoccur and persist throughout summer. To mitigate cyanobacterial bloom pollution risk, a large scale integrated monitoring and forecasting system was developed, and a series of emergency response measures were instigated based on early warning. This system has been in place for 2009-2012. With this integrated monitoring system, it was found that the detectable maximum and average cyanobacterial bloom area were similar to that before drinking water crisis, indicating that poor eutrophic status and cyanobacterial bloom had persisted without significant alleviation. It also revealed that cyanobacterial bloom would occur after the intense storm, which may be associated with the increase in buoyance of cyanobacterial colonies. Although the cyanobacterial blooms had persisted during the monitoring period, there had been a reduction in frequency and intensity of the cyanobacterial bloom induced black water agglomerates (a phenomenon of algal bloom death decay to release a large amount black dissolved organic matter), and there have been no further drinking water crises. This monitoring and response strategy can reduce the cyanobacterial bloom pollution risk, but cannot reduce eutrophication and cyanobacterial blooms, problems which will take decades to resolve. PMID:25679801

Qin, Boqiang; Li, Wei; Zhu, Guangwei; Zhang, Yunlin; Wu, Tingfeng; Gao, Guang

2015-04-28

326

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.

1998-03-01

327

Use of in vivo phycocyanin fluorescence to monitor potential microcystin-producing cyanobacterial biovolume in a drinking water source.  

PubMed

The source water of a drinking water treatment plant prone to blooms, dominated by potential microcystin-producing cyanobacteria, was monitored for two seasons in 2007-2008. In the 2008 season, the median value for potential microcystin-producing cyanobacterial biovolume was 87% of the total phytoplankton biovolume in the untreated water of the plant. Depth profiles taken above the plant's intake identified three sampling days at high risk for the contamination of the plant's raw water with potentially toxic cyanobacteria. Chlorophyceae and Bacillariophyceae caused false positive values to be generated by the phycocyanin probe when cyanobacteria represented a small fraction of the total phytoplanktonic biovolume present. However, there was little interference with the phycocyanin probe readings by other algal species when potential microcystin-producing cyanobacteria dominated the phytoplankton of the plant's untreated water. A two-tiered method for source water monitoring, using in vivo phycocyanin fluorescence, is proposed based on (1) a significant relationship between in vivo phycocyanin fluorescence and cyanobacterial biovolume and (2) the calculated maximum potential microcystin concentration produced by dominant Microcystis sp. biovolume. This method monitors locally-generated threshold values for cyanobacterial biovolume and microcystin concentrations using in vivo phycocyanin fluorescence. PMID:21157617

McQuaid, N; Zamyadi, A; Prévost, M; Bird, D F; Dorner, S

2011-02-01

328

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. PMID:20439734

Jonasson, Sara; Eriksson, Johan; Berntzon, Lotta; Spá?il, Zden?k; Ilag, Leopold L.; Ronnevi, Lars-Olof; Rasmussen, Ulla; Bergman, Birgitta

2010-01-01

329

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. PMID:21625592

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

2011-01-01

330

Comprehensive mollusk acute toxicity database improves the use of Interspecies Correlation Estimation (ICE) models to predict toxicity of untested freshwater and endangered mussel species  

EPA Science Inventory

Interspecies correlation estimation (ICE) models extrapolate acute toxicity data from surrogate test species to untested taxa. A suite of ICE models developed from a comprehensive database is available on the US Environmental Protection Agency’s web-based application, Web-I...

331

A comparison of the growth and survival of two freshwater crayfish species, Astacus leptodactylus Eschscholtz and Pacifastacus leniusculus (Dana), under different temperature and density regimes  

Microsoft Academic Search

Growth experiments carried out with two juvenile crayfish species, Astacus leptodactylus Eschscholtz and Pacifastacus leniusculus (Dana), at different temperatures and densities highlighted the problem of cannibalism under conditions aimed at intensifying\\u000a crayfish production. Cannibalism proved to be much lower in A. leptodactylus than P. leniusculus, suggesting that the former might be the better candidate for astaciculture. In the first of

Muzaffer Mustafa Harl?o?lu

2009-01-01

332

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

2011-01-01

333

Fatty Acid Composition and Levels of Selected Polyunsaturated Fatty Acids in Four Commercial Important Freshwater Fish Species from Lake Victoria, Tanzania  

PubMed Central

Fatty acids (FAs) particularly ?3 and ?6 polyunsaturated fatty acids (PUFAs) play important role in human health. This study aimed to investigate the composition and levels of selected ?3 PUFAs in four commercial fish species, Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus), Tilapia zillii, and dagaa (Rastrineobola argentea) from Mwanza Gulf in Lake Victoria. The results indicated that 36 types of FAs with different saturation levels were detected. These FAs were dominated by docosahexaenoic (DHA), eicosapentaenoic (EPA), docosapentaenoic (DPA), and eicosatetraenoic acids. O. niloticus had the highest composition of FAs (34) compared to L. niloticus (27), T. zillii (26), and R. argentea (21). The levels of EPA differed significantly among the four commercial fish species (F = 6.19, ?P = 0.001). The highest EPA levels were found in R. argentea followed by L. niloticus and O. niloticus and the lowest in T. zillii. The DPA levels showed no significant difference among the four fish species studied (F = 0.652, ?P = 0.583). The study concluded that all four commercial species collected from Mwanza Gulf are good for human health, but R. argentea is the best for consumption because it contains higher levels of ?3 FAs, mainly EPA. PMID:25610654

Robert, Agnes; Mfilinge, Prosper; Limbu, Samwel M.; Mwita, Chacha J.

2014-01-01

334

Morphological variation in Echinorhynchus truttae Schrank, 1788 and the Echinorhynchus bothniensis Zdzitowiecki & Valtonen, 1987 species complex from freshwater fishes of northern Europe  

PubMed Central

Abstract Echinorhynchus truttae and the Echinorhynchus bothniensis species complex are common parasites of salmoniform and other fishes in northern Europe. Echinorhynchus bothniensis and its sibling species Echinorhynchus 'bothniensis' are thought to be closely related to the Nearctic Echinorhynchus leidyi Van Cleave, 1924 based on morphological similarity and common usage of a mysid intermediate host. This study provides the first analysis of morphological and meristic variation in Echinorhynchus truttae and expands our knowledge of anatomical variability in the Echinorhynchus bothniensis group. Morphological variability in Echinorhynchus truttae was found to be far greater than previously reported, with part of the variance attributable to sexual dimorphism. Echinorhynchus truttae, the two species of the Echinorhynchus bothniensis group and Echinorhynchus leidyi displayed considerable interspecific overlap in the ranges of all conventional morphological characters. However, Proboscis profiler, a tool for detecting acanthocephalan morphotypes using multivariate analysis of hook morphometrics, successfully separated Echinorhynchus truttae from the other taxa. The Echinorhynchus bothniensis species group could not be reliably distinguished from Echinorhynchus leidyi (or each other), providing further evidence of the affinity of these taxa. Observations on the distribution of Echinorhynchus truttae in its definitive host population are also reported. PMID:24723769

2013-01-01

335

Fatty Acid composition and levels of selected polyunsaturated Fatty acids in four commercial important freshwater fish species from lake victoria, Tanzania.  

PubMed

Fatty acids (FAs) particularly ?3 and ?6 polyunsaturated fatty acids (PUFAs) play important role in human health. This study aimed to investigate the composition and levels of selected ?3 PUFAs in four commercial fish species, Nile perch (Lates niloticus), Nile tilapia (Oreochromis niloticus), Tilapia zillii, and dagaa (Rastrineobola argentea) from Mwanza Gulf in Lake Victoria. The results indicated that 36 types of FAs with different saturation levels were detected. These FAs were dominated by docosahexaenoic (DHA), eicosapentaenoic (EPA), docosapentaenoic (DPA), and eicosatetraenoic acids. O. niloticus had the highest composition of FAs (34) compared to L. niloticus (27), T. zillii (26), and R. argentea (21). The levels of EPA differed significantly among the four commercial fish species (F = 6.19, ?P = 0.001). The highest EPA levels were found in R. argentea followed by L. niloticus and O. niloticus and the lowest in T. zillii. The DPA levels showed no significant difference among the four fish species studied (F = 0.652, ?P = 0.583). The study concluded that all four commercial species collected from Mwanza Gulf are good for human health, but R. argentea is the best for consumption because it contains higher levels of ?3 FAs, mainly EPA. PMID:25610654

Robert, Agnes; Mfilinge, Prosper; Limbu, Samwel M; Mwita, Chacha J

2014-01-01

336

CYANOBACTERIAL TOXINS AND 2005 ISOCHAB EXPOSURE ASSESSMENT WORKGROUP  

EPA Science Inventory

The US EPA, Office of Research and Development, in collaboration with other US federal agencies, is leading the organization of an International Symposium on Cyanobacterial Harmful Algal Blooms on 6-10 September, 2005. The goal of this symposium is to develop a comprehensive nat...

337

IRIS TOXICOLOGICAL REVIEW OF CYANOBACTERIAL TOXINS: CYLINDROSPERMOPSIN (EXTERNAL REVIEW DRAFT)  

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...

338

APTAMER CAPTURE AND OPTICAL INTERFEROMETRIC DETECTION OF CYANOBACTERIAL TOXINS  

EPA Science Inventory

Cyanobacterial toxins have been identified as a health risk in source and finished waters passing through drinking water utilities in the United States. In this project, a rapid, sensitive and field usable sensor based on an aptamer modified planar waveguide interferometric se...

339

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

2008-01-01

340

The cyanobacterial genome core and the origin of photosynthesis  

PubMed Central

Comparative analysis of 15 complete cyanobacterial genome sequences, including “near minimal” genomes of five strains of Prochlorococcus spp., revealed 1,054 protein families [core cyanobacterial clusters of orthologous groups of proteins (core CyOGs)] encoded in at least 14 of them. The majority of the core CyOGs are involved in central cellular functions that are shared with other bacteria; 50 core CyOGs are specific for cyanobacteria, whereas 84 are exclusively shared by cyanobacteria and plants and/or other plastid-carrying eukaryotes, such as diatoms or apicomplexans. The latter group includes 35 families of uncharacterized proteins, which could also be involved in photosynthesis. Only a few components of cyanobacterial photosynthetic machinery are represented in the genomes of the anoxygenic phototrophic bacteria Chlorobium tepidum, Rhodopseudomonas palustris, Chloroflexus aurantiacus, or Heliobacillus mobilis. These observations, coupled with recent geological data on the properties of the ancient phototrophs, suggest that photosynthesis originated in the cyanobacterial lineage under the selective pressures of UV light and depletion of electron donors. We propose that the first phototrophs were anaerobic ancestors of cyanobacteria (“procyanobacteria”) that conducted anoxygenic photosynthesis using a photosystem I-like reaction center, somewhat similar to the heterocysts of modern filamentous cyanobacteria. From procyanobacteria, photosynthesis spread to other phyla by way of lateral gene transfer. PMID:16924101

Mulkidjanian, Armen Y.; Koonin, Eugene V.; Makarova, Kira S.; Mekhedov, Sergey L.; Sorokin, Alexander; Wolf, Yuri I.; Dufresne, Alexis; Partensky, Frédéric; Burd, Henry; Kaznadzey, Denis; Haselkorn, Robert; Galperin, Michael Y.

2006-01-01

341

Removal of cyanobacterial metabolites by nanofiltration from two treated waters.  

PubMed

Cyanobacterial metabolites, both toxic and non-toxic, are a major problem for the water industry. Nanofiltration (NF) may be an effective treatment option for removing organic micropollutants, such as cyanobacterial metabolites, from drinking water due to its size exclusion properties. A rapid bench scale membrane test (RBSMT) unit was utilised to trial four NF membranes to remove the cyanobacterial metabolites, microcystin, cylindrospermopsin (CYN), 2-methylisoborneol (MIB) and geosmin (GSM) in two treated waters sourced from the Palmer and Myponga water treatment plants. Membrane fouling was observed for both treated waters; however, only minor differences were observed between feed waters of differing natural organic matter (NOM) concentration. Low molecular weight cut-off (MWCO), or 'tight' NF, membranes afforded average removals above 90% for CYN, while removal by higher MWCO, or 'loose' NF membranes was lower. MIB and GSM were removed effectively (above 75%) by tight NF but less effectively by loose NF. Microcystin variants (MCRR, MCYR, MCLR, MCLA) were removed to above 90% by tight NF membranes; however, removal using loose NF membranes depended on the hydrophobicity and charge of the variant. Different NOM concentration in the treated waters had no effect on the removal of cyanobacterial metabolites. PMID:21339048

Dixon, Mike B; Falconet, Charlotte; Ho, Lionel; Chow, Christopher W K; O'Neill, Brian K; Newcombe, Gayle

2011-04-15

342

Coexistence and interference in two submersed freshwater perennial plants  

Microsoft Academic Search

Interactions between two codominant submersed freshwater perennial plants, Eleocharis acicularis (L.) R. and S. and Juncus pelocarpus forma submersus Fassett, were studied in a softwater lake. Analysis of segregation indicated a nonrandon arrangement of individual rosettes of each species with respect to rosettes of the other species. Factors influencing growth of the species were examined using de Wit replacement series

Nancy J. McCreary; Stephen R. Carpenter; Jack E. Chaney

1983-01-01

343

Effect of water pH on the toxicity of 2,4,5-trichlorophenol to four species of freshwater animals  

SciTech Connect

2,4,5-Trichlorophenol (TCP) is a weak acid with a pH of approximately 7.2 which is expected to have a significant effect upon its toxicity. Lumbriculus variegatus, Oncorhynchus mykiss, Pimephales promelas, and Hyalella azteca were exposed to TCP in 96 h flow-through toxicity tests. For the first two species, simultaneous tests were conducted at three pH values (7.0, 7.8, 8.6). The other two species were tested at six pH values conducted in two sets of three simultaneous tests (6.2, 7.4, 8.6 and 6.8, 8.0, 9.2). All species tested showed decreased sensitivity to TCP with increased pH of the water. Over the pH range tested, LC50s for L. variegatus varied by about 5-fold, for P. promelas by 12-fold, for H. azteca by 10-fold, and for O. mykiss by 1.5-fold. The effects of pH on TCP toxicity to P. promelas was also tested in 30 day chronic tests at pH 7.0, 7.8 and 8.6. Survival in these tests was affected by pH similarly to the acute tests. Growth also was less severely affected at higher pH.

Brooke, L.T.; Markee, T.; Vande Venter, F. [Univ. of Wisconsin, Superior, WI (United States); Spehar, R.; Erickson, R. [Environmental Protection Agency, Duluth, MN (United States). Environmental Research Lab.

1994-12-31

344

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.

2003-04-01

345

Cyanobacterial bloom detection based on coherence between ferrybox observations  

NASA Astrophysics Data System (ADS)

Cyanobacterial bloom detection from flow-through optical sensors on ships-of-opportunity ('ferryboxes') is challenging in periods of strong stratification and due to varying cell physiology and phytoplankton community composition. Wavelet coherence analysis between ferrybox parameters (chlorophyll-a fluorescence, phycocyanin fluorescence, turbidity) was used to delineate blooms in a dataset of ten ferrybox transects, recorded during the 2005 cyanobacterial bloom season in the Baltic Sea. Independent wind speed and sea-surface temperature data were used to classify areas of cyanobacterial dominance as mixed, stratified, or surfacing bloom. These classified subsets of ferrybox observations were compared against remotely sensed chlorophyll-a concentrations, which resulted in a scheme for the interpretation of surface water phytoplankton biomass from multi-source observations. Ferrybox optical signals were significantly coherent from the onset until the end of the cyanobacterial bloom period under both stratified and mixed conditions. This suggests that the coherence analysis is sensitive to high-level community composition. Strongly stratified and suspected surfacing bloom was associated with unrealistically high remotely sensed chlorophyll-a estimates, indicating the need to flag stratified bloom areas when interpreting remote sensing imagery. The ferrybox fluorescence and turbidity signals at the 5-m sampling depth were, paradoxically, low under these conditions, suggesting that direct comparison between remote sensing and flow-through observations is not useful for stratified blooms. Correlations between ferrybox measurements and remotely sensed observations improved consistently when stratified or surfacing cyanobacterial bloom was excluded from the regression. It is discussed how coherence analysis of ferrybox observations can aid the interpretation of remotely sensed data in situations where meteorological observations suggest incomplete vertical mixing.

Groetsch, Philipp M. M.; Simis, Stefan G. H.; Eleveld, Marieke A.; Peters, Steef W. M.

2014-12-01

346

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. PMID:22423312

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

2008-01-01

347

Spatial and temporal variability in the relationship between cyanobacterial biomass and microcystins.  

PubMed

The increasing incidence of toxic cyanobacterial blooms, together with the difficulties to reliably predict cyanobacterial toxin (e.g. microcystins) concentration, has created the need to assess the predictive ability and variability of the cyanobacterial biomass-microcystin relationship, which is currently used to assess the risk to human and ecosystems health. To achieve this aim, we assessed the relationship between cyanobacterial biomass and microcystin concentration on a spatiotemporal scale by quantifying the concentration of cyanobacterial biomass and microcystin in eight lakes over 9 months. On both a temporal and spatial scale, the variability of microcystin concentration exceeded that of cyanobacterial biomass by up to four times. The relationship between cyanobacterial biomass and microcystin was weak and site specific. The variability of cyanobacterial biomass only explained 25 % of the variability in total microcystin concentration and 7 % of the variability of cellular microcystin concentration. Although a significant correlation does not always imply real cause, the results of multiple linear regression analysis suggest that the variability of cyanobacterial biomass and cellular microcystin concentration is influenced by salinity and total phosphorus, respectively. The weak cyanobacterial biomass-microcystin relationship, coupled with the fact that microcystin was present in concentrations exceeding the WHO drinking water guidelines (1 ?g?L(-1)) in most of the collected samples, emphasizes the high risk of error connected to the traditional indirect microcystin risk assessment method. PMID:23232847

Sinang, Som Cit; Reichwaldt, Elke S; Ghadouani, Anas

2013-08-01

348

The eastern swamp crayfish Gramastacus lacus sp. n. (Decapoda, Parastacidae) a new species of freshwater crayfish from coastal New South Wales, Australia  

PubMed Central

Abstract Gramastacus lacus sp. n., is described from coastal lowlands of the Central and Mid North Coast regions of New South Wales, Australia. Gramastacus lacus has a restricted distribution in ephemeral habitats, being dependent on regular natural flooding and drying cycles, and burrows for survival during temporary dry cycles. Documented are population distributions in lowland habitats (3–48 m, a.s.l.) from Wamberal Lagoon, north along the coastal strip to Wallis Lake. The species is small, reaching a maximum weight of 7 grams and 21.3 mm OCL, and distinguished by a large male genital papilla, large raised post orbital ridges, laterally compressed carapace and elongated chelae. PMID:24715801

McCormack, Robert B.

2014-01-01

349

Davis Pond Freshwater Prediversion Biomonitoring Study: Freshwater Fisheries and Eagles  

USGS Publications Warehouse

In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle (Haliaeetus leucocephalus) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet (Mugil cephalus), omnivorous blue catfish (Ictalurus furcatus), and carnivorous largemouth bass (Micropterus salmoides). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams (Rangia cuneata) were collected at the downstream marsh sites, and zebra mussels (Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate pesticides and other contaminants. Biomarker data on individual fish, generated at the USGS National Wetlands Research Center (Lafayette, La.), included percent white blood cells in whole blood, spleen weight to body weight ratio, liver weight to body weight ratio, condition factor, splenic macrophage aggregates, and liver microsomal 7-ethoxyresorufin-o-deethylase (EROD) activity. Fish age was estimated by comparing total lengths with values from the same species in the Southeast United States as determined from the literature. Contaminant analyses were coordinated by the U.S. Fish and Wildlife Service (USFWS) Analytical Control Facility (Laurel, Md.), where residues of organochlorine (OC) pesticides, total polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs), and trace elements were determined. The organic contaminant data were generated at the Mississippi State University Chemical Lab (Mississippi State, Miss.), and the inorganic contaminant data were generated by the Texas A&M University Geochemical and Environmental Research Group (College Station, Tex.). Statistical tests were performed to assess relationships among contaminants, fish age, fish species, and collection sites.

Jenkins, Jill A.; Bourgeois, E. Beth; Jeske, Clint W.

2008-01-01

350

ACUTE LETHAL CONCENTRATIONS OF CAFFEINE ON NON-TARGET FRESHWATER ORGANISMS  

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...

351

First records of freshwater molluscs from the ecological reserve El Edén, Quintana Roo, Mexico  

Microsoft Academic Search

The diversity of the freshwater molluscs at El Edén was unknown. This is the fi rst treatment of them, allowing us to compare spatial and temporal species distribution. Eleven species of freshwater molluscs were found in 2 surveys carried in March (dry season) and September (rainy season) 1998 at the reserve El Edén. A total of 266 individuals were collected;

Roberto Cózatl-Manzano; Edna Naranjo-García

352

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

2005-01-01

353

Global diversity of bryozoans (Bryozoa or Ectoprocta) in freshwater  

Microsoft Academic Search

The present study considers 88 bryozoan species occurring in freshwater: 69 phylactolaemate and 19 gymnolaemate species. Roughly\\u000a 49% of these species are confined to one zoogeographical region. The cosmopolitan status of species like Fredericella sultana, Plumatella repens or P. emarginata has to be reconsidered. Among the Phylactolaemata, which are phylogenetically older than the Gymnolaemata, the gelatinous\\u000a species (Lophopodidae, Pectinatellidae, Cristatellidae)

Jos A. Massard; Gaby Geimer

2008-01-01

354

Synthetic musks in the environment. Part 1: Species-dependent bioaccumulation of polycyclic and nitro musk fragrances in freshwater fish and mussels.  

PubMed

Bioaccumulation of polycyclic musks (HHCB, AHTN) and nitro musks (musk xylene, musk ketone, and their amino metabolites) in aquatic biota was investigated by analyzing 18 fish samples (rudd, tench, crucian carp, eel) and 1 pooled zebra mussel sample from the pond of a municipal sewage treatment plant. Furthermore, water samples taken at the effluent of the sewage plant as well as water samples and two series of semipermeable membrane devices (SPMDs) from the pond were included. This comprehensive data set allowed the determination of species-dependent bioaccumulation factors on a lipid basis (BAF(L)), e.g., for HHCB the BAF(L) in tench were more than 20 times higher than in eel. The BAF(L) for HHCB and AHTN in biota were lower than the partition coefficients K(SPMD/W) obtained from SPMD samples, which are assumed to represent model bioconcentration values. This stresses that metabolism of these compounds in fish must not be neglected. PMID:11994785

Gatermann, R; Biselli, S; Hühnerfuss, H; Rimkus, G G; Hecker, M; Karbe, L

2002-05-01

355

Effect of Incubation Temperature on the Detection of Thermophilic Campylobacter Species from Freshwater Beaches, Nearby Wastewater Effluents, and Bird Fecal Droppings  

PubMed Central

This large-scale study compared incubation temperatures (37°C versus 42°C) to study the detection of thermophilic Campylobacter species, including Campylobacter jejuni, C. coli, and C. lari, in various surface water samples and bird fecal droppings around Hamilton Harbor, Lake Ontario. The putative culture isolates obtained from incubation temperatures of 37 and 42°C were confirmed by Campylobacter genus- and species-specific triplex PCR assays targeting the 16S rRNA gene and the 16S-23S rRNA gene internal transcribed spacer (ITS) region. A total of 759 water, wastewater, and bird fecal dropping samples were tested. Positive amplification reactions for the genus Campylobacter were found for 454 (60%) samples incubated at 37°C, compared to 258 (34%) samples incubated at 42°C. C. jejuni (16%) and C. lari (12%) were detected significantly more frequently at the 42°C incubation temperature than at 37°C (8% and 5%, respectively). In contrast, significantly higher rates of C. coli (14%) and other Campylobacter spp. (36%) were detected at the 37°C incubation temperature than at 42°C (8% and 7%, respectively). These results were consistent across surface water, wastewater, and bird fecal dropping samples. At times, Campylobacter spp. were recovered and detected at 37°C (3% for C. jejuni, 10% for C. coli, and 3% for C. lari) when the same samples incubated at 42°C were negative. A significantly higher rate of other Campylobacter spp. was detected only at 37°C (32%) than only at 42°C (3%). These results indicate that incubation temperature can significantly influence the culturability and detection of thermophilic and other fastidious Campylobacter spp. and that a comprehensive characterization of the Campylobacter spp. in surface water, wastewaters, or bird fecal droppings will require incubation at both 37 and 42°C. PMID:24077717

Hill, Stephen; Nowak, Eva; Edge, Thomas A.

2013-01-01

356

Pathologic findings and toxin identification in cyanobacterial (Nodularia spumigena) intoxication in a dog.  

PubMed

A 3-year-old Cairn Terrier dog that had been in contact with sea water containing cyanobacteria (blue-green algae) was euthanized because of acute hepatic failure and anuria after a 5-day illness. Histologic findings included lytic and hemorrhagic centrilobular hepatocellular necrosis and renal tubular necrosis. The cyanotoxin nodularin was detected in liver and kidney by high-performance liquid chromatography-mass spectrometry. Nodularin is a potent hepatotoxin produced by the algal species Nodularia spumigena. The intensity of algal blooms has increased during the past decades in the Baltic Sea region, thus increasing the risk for intoxications in domestic and wild animals. The authors describe the pathologic findings of cyanobacterial toxicosis in a dog with direct identification of the toxin from organ samples. PMID:21825312

Simola, O; Wiberg, M; Jokela, J; Wahlsten, M; Sivonen, K; Syrjä, P

2012-09-01

357

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.

2011-12-01

358

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. PMID:22539906

Bogutskaya, Nina G.; Zupan?i?, Primož; Bogut, Ivan; Naseka, Alexander M.

2012-01-01

359

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. PMID:22456448

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

2012-01-01

360

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

PubMed

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-Har(2)] nodularin, which contains L-homoarginine instead of L-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-Har(2)] 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-Har(2)] nodularin in a non-Nodularia species and the production of cyanobacterial hepatotoxin by a symbiont in planta. PMID:22456448

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

2012-10-01

361

Causes and Controls of Freshwater Drum Mortality during Transportation  

Microsoft Academic Search

The freshwater drum Aplodinotus grunniens is an abundant and underutilized species in Lake Eric. Transportation of live fish from commercial shore seines to pay-fishing lakes causes high immediate and delayed mortality during warm summer months. Freshwater drums transported 6 hours had 4% immediate mortality and 94% delayed mortality (over 1–2 weeks). Salt (5 g\\/liter NaCl), low hauled-fish densities (60 g

David L. Johnson; Michael T. Metcalf

1982-01-01

362

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. PMID:20613986

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

2010-01-01

363

Differential regulation of hsp70 genes in the freshwater key species Gammarus pulex (Crustacea, Amphipoda) exposed to thermal stress: effects of latitude and ontogeny.  

PubMed

Temperature is one of the main abiotic factors influencing the distribution and abundance of organisms. In the Rhône River Valley, populations of the crustacean Gammarus pulex are distributed along a 5 °C thermal gradient from the North to the South of the valley. In this present work, we investigated the heat shock response of G. pulex according to latitudinal distribution (northern vs. southern populations) and ontogeny (adults vs. embryos from early stages). We isolated two isoforms (one constitutive hsc70 and one inducible hsp70) of heat shock proteins 70 (HSP70) and quantitatively compared their amounts of mRNA after heat shocks, using real-time PCR. Whereas the hsc70 (constitutive) gene did not vary between the two populations, a significant effect of the population was observed on the expression of the hsp70 (inducible) gene in adult specimens. The northern population of amphipods showed a greater magnitude of induction and a 2 °C lower onset temperature when compared to the southern population, suggesting that the northern population is more affected by elevated temperature than the southern one. We demonstrated that the expression of hsp70 may play a crucial role in the persistence of biogeographical patterns of G. pulex, since it reflects the natural distribution of this species along the latitudinal thermal gradient. A differential regulation of hsc70 gene was also observed according to the ontogenetic stage, with a switch from heat inducible in early life stages to constitutively and highly expressed in adults. These findings demonstrate the importance of considering the entire life cycle to better understand the adaptive response to thermal stress. PMID:25588676

Cottin, Delphine; Foucreau, Natacha; Hervant, Frédéric; Piscart, Christophe

2015-04-01

364

Strong population genetic structure and its management implications in the mud carp Cirrhinus molitorella, an indigenous freshwater species subject to an aquaculture and culture-based fishery.  

PubMed

This study investigated population genetic structure and diversity of mud carp Cirrhinus molitorella, a species widely used in aquaculture and culture-based fisheries in China and Mekong River riparian countries. Seven newly developed and one published microsatellite DNA markers were used to analyse samples from six wild locations, four hatchery broodstocks and one farmed site from the Mekong, Red and Pearl Rivers. Significant genetic structure was detected in C. molitorella, with isolation-by-distance being a strong force in the Mekong. Pair-wise F(ST) , Fisher's exact tests for population differentiation, permutation tests and individual-based structure analysis all support the recognition of a sample originating from Toul Krasaing Lake (Cambodia) and one between Kratie and Stung Treng (Cambodia) as distinct from the remainder of the sampled range. Samples from the main upper Mekong and the Nam Khan River were significantly differentiated, but on a time scale inferred to be short (i.e. by genetic drift, not sufficient for evolution of new microsatellite alleles). The Mekong stock of C. molitorella was strongly differentiated from those from the Red and Pearl Rivers, inferred to be on an evolutionary time scale. Finer-scale sampling is warranted to further improve the understanding of genetic interactions among fish from the Mekong and its tributaries. Detailed studies on the ecology of C. molitorella (e.g. migration pathways and preferred spawning habitats) would provide useful information to explain the patterns of genetic structure detected here, and deepen insights about evolutionary distinctiveness of the population units. PMID:22380559

Nguyen, T T T; Sunnucks, P

2012-03-01

365

Interannual variability of cyanobacterial blooms in Lake Erie.  

PubMed

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

2012-01-01

366

Comparison of 17 biotests for detection of cyanobacterial toxicity.  

PubMed

The aim of the present study was to compare the sensitivity of 17 acute bioassays of cyanobacterial toxicity by assessment of crude extracts of three cyanobacterial samples (all dominated by Microcystis sp. but substantially differing in microcystin-LR content). Toxicity of the fractions prepared by solid-phase extraction (SPE) for microcystins was also determined. The most sensitive bioassay was the 24-h test with crustacean Thamnocephalus platyurus, which elicited high lethality in the samples and also in fractions without microcystins. The fruit fly Drosophila melanogaster, protozoans Spirostomum ambiguum and Tetrahymena termophyla, and the crustacean Daphnia pulex formed the second group of sensitive bioassays. Good selective toxicity response to microcystins also was observed in the weakly sensitive biotests with the oligochaete Tubifex tubifex and the rotifer Brachionus calyciflorus. Preconcentration of microcystins by SPE substantially decreased variation of the results in bioassays and improved the discriminating potential of most assays employed. PMID:15269901

Marsálek, Blahoslav; Bláha, Ludek

2004-08-01

367

Cyanobacterial chemotaxis to extracts of host and nonhost plants.  

PubMed

Chemotaxis may be important when forming cyanobacterial symbioses. However, knowledge of cyanobacterial attraction towards plants and factors affecting chemotaxis is limited. Chemo-attraction was observed in Nostoc strains 8964:3 and PCC 73102 towards exudate or crushed extract of the natural hosts Gunnera manicata, Cycas revoluta and Blasia pusilla, and the nonhost plants Trifolium repens, Arabidopsis thaliana and Oryza sativa. As all tested plant extracts generated chemotaxis, the possibility to attract cyanobacteria may be widespread in plants. Chemotaxis was reduced by increased temperature and darkness and was stimulated by phosphorous and iron starvation and elevated salt concentration. Sugars (arabinose, galactose, and glucose) had a positive effect on chemotaxis, whereas flavonoids (chrysin and naringenin) and amino acids (methionine, glycine, serine, phenylalanine, glutamine, and lysine) had no effect. PMID:16466377

Nilsson, Malin; Rasmussen, Ulla; Bergman, Birgitta

2006-03-01

368

A single phosphorus treatment doubles growth of cyanobacterial lichen transplants.  

PubMed

Lichens are reputedly slow growing and become unhealthy or die in response to supplements of the usual limiting resources, such as water and nitrogen. We found, however, that the tripartite cyanobacterial lichen Lobaria pulmonaria doubled in annual biomass growth after a single 20-minute immersion in a phosphorus solution (K2HPO4), as compared to controls receiving no supplemental phosphorus. This stimulation of cyanolichens by phosphorus has direct relevance to community and population ecology of lichens, including improving models of lichen performance in relation to air quality, improving forest management practices affecting old-growth associated cyanolichens, and understanding the distribution and abundance of cyanolichens on the landscape. Phosphorus may be as important a stimulant to cyanobacterial-rich lichen communities as it is to cyanobacteria in aquatic ecosystems. PMID:19323240

McCune, Bruce; Caldwell, Bruce A

2009-02-01

369

Interannual Variability of Cyanobacterial Blooms in Lake Erie  

PubMed Central

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.

2012-01-01

370

Antibiotic activity of two Anabaena species against four fish pathogenic Aeromonas species  

Microsoft Academic Search

Three organic extracts (chloroform, ethyl acetate and n-butanol) of ten cyanobacterial species (Anabaena solitaria, Anabaena variabilis, Anabaena cylindrical, Anabaena spiroides, Anabaena circinalis, Oscillatoria ornate, Oscillatoria salins, Oscillatoria tenuis, Oscillatoria rubescens and Oscillatoria prolifica) were investigated for their antibacterial activities against 4 fish pathogenic bacterial species belonging to genus Aeromonas, namely, Aer. salmonicida, Aer. hydrophila, Aer. formicans and Aer. liquefaciens using

Neveen Abdel-Raouf; Ibraheem B. M. Ibraheem

371

Biomes: Freshwater and Seawater  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com 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.

372

Promotion of oxidative stress in the aquatic macrophyte Ceratophyllum demersum during biotransformation of the cyanobacterial toxin microcystin-LR.  

PubMed

Cyanobacterial toxins have been shown to have adverse effects on mammals, birds and fish and are therefore being increasingly recognised as a potent stress and health hazard factor in aquatic ecosystems. Microcystins, which are cyclic heptapeptides and a main group of the cyanotoxins, are mainly retained within the producer-cells during cyanobacterial bloom development. However, these toxins are released into the surrounding medium by senescence and lysis of the blooms. The released toxins could then come into contact with a wide range of aquatic organisms including invertebrates, fish and aquatic plants. In many organisms, biotransformation of the toxins will take place via several glutathione-related conjugate. During the biotransformation process in which the toxin and the toxin conjugate are broken down, the formation of reactive oxygen species might occur. These reactive oxygen species activate several antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase and also influence the glutathione-ascorbate cycle. Aim of this study was to investigate formation of the glutathione-conjugate, activation of glutathione S-transferases and the elevation of several antioxidant enzymes giving evidence for the promotion of oxidative stress by microcystins. During exposure of Ceratophyllum demersum to the cyanobacterial toxin microcystin-LR in an concentration of 5.0 microg/L, an elevation of microsomal and cytosolic glutathione S-transferase was measured, showing the beginning formation of the glutathione-toxin conjugate. The superoxide dismutase as well as in parallel the hydrogen peroxide level increased giving evidence for oxidative stress in the aquatic plant. Other reactive oxygen detoxifiying enzymes were also elevated and the glutathione pool, expressed in reduced glutathione and glutathione disulfide concentration was changed accordingly. PMID:15550274

Pflugmacher, Stephan

2004-12-10

373

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

374

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

2011-01-01

375

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

2005-01-01

376

Assessment of Freshwater Fish Assemblages and Their Habitats in the National Park Service System of the Southeastern United States  

Microsoft Academic Search

The southeast region of the United States contains the highest diversity of freshwater fish species in the country: approximately 662 species. Existing protected areas like units of the National Park Service (NPS) should reflect this biodiversity, but there has been no broad-scale assessment. We compiled several data sets identifying native freshwater fish species distributions in and surrounding NPS units and

James M. Long; Nathan P. Nibbelink; Kevin T. McAbee; Julie W. Stahli

2012-01-01

377

Use of cyanobacterial diazotrophic technology in rice agriculture  

SciTech Connect

Diazotrophic cyanobacteria are photoautotrophic organisms that require sunlight as a sole energy source for the fixation of carbon and nitrogen. Therefore, they have great potential as biofertilizers, and their use will decrease fuel demand for fertilizer production. The agronomic potential of heterocystous cyanobacteria, either free-living or in symbiotic association with water fern Azolla, has long been recognized. This has led to the development of small scale biotechnology involving the use of paddy soils with appropriate cyanobacterial strains as biofertilizers in rice culture, as has been reported from China, Egypt, Philippines, and India. Besides increasing soil fertility and sustaining rice yield, these forms are also reported to benefit rice seedlings by producing growth-promoting substances, the nature of which is said to resemble gibberellins. Whereas the incorporation of nif genes into the rice plants by using tissue culture and modern genetic tools remain one of the ambitious research goals, the use of cyanobacterial diazotrophic technology in rice agriculture offers an immediate or even long-term alternative to synthetic nitrogen fertilizers, particularly in developing countries and the world as a whole. However, one of the weaknesses in this technology is the heavy application of several toxic agrochemicals, especially herbicides, which are reported in most cases as inhibitors of cyanobacterial diazotrophic growth, and in some cases as mutagenic. Naturally, a successful biotechnology requires the selection of suitable diazotrophic strains, as biofertilizers, that could tolerate the field-dose concentrations of herbicides and secrete ammonia.

Tiwari, D.N.; Kumar, A.; Mishra, A.K. [Banaras Hindu Univ., Varanasi (India)

1991-12-31

378

Mechanics and resonance of the cyanobacterial circadian oscillator.  

PubMed

Recent experiments elucidated the structure and function of the cyanobacterial circadian oscillator, which is driven by sunlight intensity variation and therefore by Earth's rotation. It is known that cyanobacteria appeared about 3.5 billion years ago and that Earth's rotational speed is continuously decreasing because of tidal friction. What is the effect of the continuous slowdown of Earth's rotation on the operation of the cyanobacterial oscillator? To answer this question we derived the oscillator's equation of motion directly from experimental data, coupled it with Earth's rotation and computed its natural periods and its resonance curve. The results show that there are two resonance peaks of the "cyanobacterial oscillator-rotating Earth" system, indicating that cyanobacteria used more efficiently the solar energy during the geological period in which the day length varied from about 11 to 15h and make more efficient use of solar energy at the geological period which started with a day length of 21h and will end at a day length of 28h. PMID:22425611

Karafyllidis, Ioannis G

2012-08-01

379

Environmentally benign periphyton bioreactors for controlling cyanobacterial growth.  

PubMed

Microporous suspended bioreactors immobilized with periphytons were submerged between sediments and overlying water to control phosphorus release and cyanobacterial (Microcystis aeruginosa) growth. The results showed that the periphyton mainly consisted of bacteria and diatoms. The application of periphyton bioreactor decreased the levels of exchange phosphorus (Exch-P) in sediments from 1.69 to 0.49 mg g(-1) and total phosphorus (TP) from 0.75 to 0.30 mg L(-1). The significant reduction of the total dissolved phosphorus (TDP) content was not only beneficial for the decrease of the cyanobacterial growth, but also stimulates the periphyton to produce natural cyanobacterial inhibitors such as gallic acid and ethyl-2-methylacetoacetate. These synergistic effects led to the growth inhabitation of M. aeruginosa when the initial concentrations of M. aeruginosa were less than 119.3 microg L(-1). This study provides an environmentally-friendly and publically acceptable method of controlling bacterial blooms when compared to traditional addition of chemicals. PMID:20702088

Wu, Yonghong; Zhang, Shanqing; Zhao, Huijun; Yang, Linzhang

2010-12-01

380

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. PMID:9729605

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

1998-01-01

381

Global diversity of freshwater birds (Aves)  

Microsoft Academic Search

Among the 10,000 birds species living on earth, 5% (e.g., 560) need imperatively freshwater habitat in order to satisfy at\\u000a least one of their life history traits. About 11 completed families could even disappear if their wetland habitat left. About\\u000a 10% (58) of these can be considered as endemic. Africa contains the biggest number of endemic (20) and more precisely

Olivier Dehorter; Matthieu Guillemain

382

Global diversity of freshwater birds (Aves)  

Microsoft Academic Search

Among the 10,000 birds species living on earth, 5% (e.g., 560) need imperatively freshwater habitat in order to satisfy at\\u000a least one of their life history traits. About 11 completed families could even disappear if their wetland habitat left. About\\u000a 10% (58) of these can be considered as endemic. Africa contains the biggest number of endemic (20) and more precisely

Olivier Dehorter; Matthieu Guillemain

2008-01-01

383

Phytotoxic effects of the cyanobacterial neurotoxin anatoxin-a: morphological, physiological and biochemical responses in aquatic macrophyte, Ceratophyllum demersum.  

PubMed

Anatoxin-a is one of the common and major cyanobacterial neurotoxins acting as a powerful agonist at nicotinic acetylcholine receptors (nAChR). In recent years, the toxin has become the focus of public attention, due to the mass development of cyanobacteria (cyanobacterial blooms) in freshwater bodies triggered by eutrophication and climate change. Anatoxin-a is suspected to have a distinct toxic mechanism depending on physiological and nervous systems in exposed organisms. The numerous researches have been actively conducted with respect to the toxic effects of anatoxin-a on mammals; however, little research has aimed at its possible effects on aquatic plants, wherein well-structured nervous system is absent with the lack of various components of the acetylcholine mechanism. In this study, submerged macrophyte Ceratophyllum demersum (C. demersum) was adopted to examine the effects of anatoxin-a on morphological (growth), physiological (photosynthetic pigment contents) and biochemical (hydrogen peroxide level, biotransformation and antioxidative enzymes) responses in the aquatic plant at environmentally relevant concentrations (0.005, 0.05, 0.5, 5 and 50 ?g/L). The significant elevation of antioxidative enzymes in parallel with increased formation of hydrogen peroxide appeared from 0.5 ?g/L of anatoxin-a. In the measurement of photosynthetic pigments, the decrease in chlorophyll a content was detected at 5 and 50 ?g/L, whereas the increase in carotenoids/total chlorophyll was observed from 0.05 ?g/L. Accordingly, the alteration in growth was manifested in the presence of 5 and 50 ?g/L of anatoxin-a. The results clearly indicate that anatoxin-a can disrupt homeostasis of C. demersum through induction of oxidative stress; furthermore this aquatic plant possesses effective defense mechanisms to cope with low concentrations of anatoxin-a. PMID:23578514

Ha, Mi-Hee; Pflugmacher, Stephan

2013-08-01

384

The effect of rock composition on cyanobacterial weathering of crystalline basalt and rhyolite.  

PubMed

The weathering of volcanic rocks contributes significantly to the global silicate weathering budget, effecting carbon dioxide drawdown and long-term climate control. The rate of chemical weathering is influenced by the composition of the rock. Rock-dwelling micro-organisms are known to play a role in changing the rate of weathering reactions; however, the influence of rock composition on bio-weathering is unknown. Cyanobacteria are known to be a ubiquitous surface taxon in volcanic rocks. In this study, we used a selection of fast and slow growing cyanobacterial species to compare microbial-mediated weathering of bulk crystalline rocks of basaltic and rhyolitic composition, under batch conditions. Cyanobacterial growth caused an increase in the pH of the medium and an acceleration of rock dissolution compared to the abiotic controls. For example, Anabaena cylindrica increased the linear release rate (R(i)(l)) of Ca, Mg, Si and K from the basalt by more than fivefold (5.21-12.48) and increased the pH of the medium by 1.9 units. Although A. cylindrica enhanced rhyolite weathering, the increase in R(i)(l) was less than threefold (2.04-2.97) and the pH increase was only 0.83 units. The R(i)(l) values obtained with A. cylindrica were at least ninefold greater with the basalt than the rhyolite, whereas in the abiotic controls, the difference was less than fivefold. Factors accounting for the slower rate of rhyolite weathering and lower biomass achieved are likely to include the higher content of quartz, which has a low rate of weathering and lower concentrations of bio-essential elements, such as, Ca, Fe and Mg, which are known to be important in controlling cyanobacterial growth. We show that at conditions where weathering is favoured, biota can enhance the difference between low and high Si-rock weathering. Our data show that cyanobacteria can play a significant role in enhancing rock weathering and likely have done since they evolved on the early Earth. PMID:22694082

Olsson-Francis, K; Simpson, A E; Wolff-Boenisch, D; Cockell, C S

2012-09-01

385

Tetanus after envenomations caused by freshwater stingrays.  

PubMed

Injuries caused by freshwater stingray are common in several regions of South America, although they are underreported. The riverside inhabitants are the main victims in the Amazonian and Midwest regions of South America. The fishermen are injured mainly in the new focus of colonization of the rivers by freshwater stingrays. With the increasing population in these regions, where freshwater stingrays are found, there has been a significant increase in injuries within the general population. The highest increase occurred among tourists from other regions, where these animals are not known, when visiting these areas. The envenomations from the stingray causes prolonged and intense pain, both local and regionally. Generally these are associated with other local inflammatory manifestations, such as swelling and erythema. The injury often progresses to necrosis and it is considered potentially tetanogenic. A secondary infection is also a frequent local complication and most frequently is caused by Aeromonas species, usually Aeromonas hydrophila. Herein we report the first 2 cases of tetanus after freshwater stingray injuries: a 51-year-old men who had tetanus and recovered without sequel and the second a 67-year-old men who had severe tetanus and a deep, necrotizing soft-tissue infection with sepsis, septic shock and evolution to death. PMID:25576234

Torrez, Pasesa P Q; Quiroga, Mariana M; Said, Renato; Abati, Paulo A M; França, Francisco O S

2015-04-01

386

Similarities in Acute Temperature Preferences of Freshwater Fishes  

Microsoft Academic Search

A statistical analysis of new and published laboratory data revealed strong geographic similarities in acute (up to 4-hour) temperature preferences for several freshwater fishes. Regression models developed from our laboratory studies predicted acute temperature preferences of species from other geographic areas. Species within a family (three cyprinids, two ictalurids, and six centrarchids were tested) have similar acute preferenda, except that

Dilip Mathur; Robert M. Schutsky; Edmund J. Purdy Jr; Carl A. Silver

1981-01-01

387

Similarities in acute temperature preferences of freshwater fishes  

Microsoft Academic Search

A statistical analysis of new and published laboratory data revealed strong geographic similarities in acute (up to 4-h) temperature preferences for several freshwater fishes. Regression models developed from our laboratory studies predicted acute temperature preferences of species from other geographic areas. Species within a family (three cyprinids, two ictalurids, and six centrarchids were tested) have similar acute preferenda, except that

DILIP MATHUR; ROBERT M. SCHUTSKY; EDMUND J. PURDY; CARL A. SILVER

1981-01-01

388

Toxicity of rotenone to giant river freshwater prawn Macrobrachium rosenbergii  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aquaculturists have often suffered predation losses in the production of freshwater giant river prawn Macrobrachium rosenbergii due to the presence of wild fish species in culture ponds. The piscicide rotenone is widely used to remove undesirable fish species from ponds. Although evidence in the t...

389

Parasite communities of freshwater fish under flood conditions  

Microsoft Academic Search

The parasite communities of the freshwater fish species roach (Rutilus rutilus), bitterling (Rhodeus sericeus amarus) and perch (Perca fluviatilis) were investigated during a major flood. Differences in parasite community structure due to changes in the host environment were expected. We therefore tested for differences in parasite species abundance and diversity as a consequence of the flood. Potential changes in parasite

Dušan Kadlec; Andrea Šimková; Ji?í Jarkovský; Milan Gelnar

2003-01-01

390

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 causes…

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

391

Loons in freshwater lakes  

Microsoft Academic Search

Loons (Gaviidae) divide their annual cycle between salt and freshwater habitat, the latter being the site of breeding activites. Territorial requirements include sufficient size to permit runs of more than 100 m for take-off and landings; food for chicks and water clarity sufficient to permit foraging for it at depths generally = 5 m; protected nest sites, preferably islands; and

Judith W. McIntyre

1994-01-01

392

Cyanobacterial carboxysomes: microcompartments that facilitate CO2 fixation.  

PubMed

Carboxysomes are extraordinarily efficient proteinaceous microcompartments that encapsulate the primary CO2-fixing enzyme (ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBisCO) in cyanobacteria and some proteobacteria. These microbodies form part of a CO2-concentrating mechanism (CCM), operating together with active CO2 and HCO3(-) uptake transporters which accumulate HCO3(-) in the cytoplasm of the cell. Cyanobacteria (also known as blue-green algae) are highly productive on a global scale, especially those species from open-ocean niches, which collectively contribute nearly 30% of global net primary fixation. This productivity would not be possible without a CCM which is dependent on carboxysomes. Two evolutionarily distinct forms of carboxysome are evident that encapsulate proteobacterial RuBisCO form-1A or higher-plant RuBisCO form- 1B, respectively. Based partly on RuBisCO phylogeny, the two carboxysome types are known either as ?-carboxysomes, found in predominantly oceanic cyanobacteria (?-cyanobacteria) and some proteobacteria, or as ?-carboxysomes, found mainly in freshwater/estuarine cyanobacteria (?-cyanobacteria). Both carboxysome types are believed to have evolved in parallel as a consequence of fluctuating atmospheric CO2 levels and evolutionary pressure acting via the poor enzymatic kinetics of RuBisCO. The three-dimensional structures and protein components of each carboxysome type reflect distinct evolutionarily strategies to the same major functions: subcellular compartmentalization and RuBisCO encapsulation, oxygen exclusion, and CO2 concentration and fixation. PMID:23920493

Rae, Benjamin D; Long, Benedict M; Whitehead, Lynne F; Förster, Britta; Badger, Murray R; Price, G Dean

2013-01-01

393

Molecular mechanism of photoactivation and structural location of the cyanobacterial orange carotenoid protein.  

PubMed

The orange carotenoid protein (OCP) plays a photoprotective role in cyanobacterial photosynthesis similar to that of nonphotochemical quenching in higher plants. Under high-light conditions, the OCP binds to the phycobilisome (PBS) and reduces the extent of transfer of energy to the photosystems. The protective cycle starts from a light-induced activation of the OCP. Detailed information about the molecular mechanism of this process as well as the subsequent recruitment of the active OCP to the phycobilisome are not known. We report here our investigation on the OCP photoactivation from the cyanobacterium Synechocystis sp. PCC 6803 by using a combination of native electrospray mass spectrometry (MS) and protein cross-linking. We demonstrate that native MS can capture the OCP with its intact pigment and further reveal that the OCP undergoes a dimer-to-monomer transition upon light illumination. The reversion of the activated form of the OCP to the inactive, dark form was also observed by using native MS. Furthermore, in vitro reconstitution of the OCP and PBS allowed us to perform protein chemical cross-linking experiments. Liquid chromatography-MS/MS analysis identified cross-linking species between the OCP and the PBS core components. Our result indicates that the N-terminal domain of the OCP is closely involved in the association with a site formed by two allophycocyanin trimers in the basal cylinders of the phycobilisome core. This report improves our understanding of the activation mechanism of the OCP and the structural binding site of the OCP during the cyanobacterial nonphotochemical quenching process. PMID:24359496

Zhang, Hao; Liu, Haijun; Niedzwiedzki, Dariusz M; Prado, Mindy; Jiang, Jing; Gross, Michael L; Blankenship, Robert E

2014-01-14

394

Health-Based Cyanotoxin Guideline Values Allow for Cyanotoxin-Based Monitoring and Efficient Public Health Response to Cyanobacterial Blooms  

PubMed Central

Human health risks from cyanobacterial blooms are primarily related to cyanotoxins that some cyanobacteria produce. Not all species of cyanobacteria can produce toxins. Those that do often do not produce toxins at levels harmful to human health. Monitoring programs that use identification of cyanobacteria genus and species and enumeration of cyanobacterial cells as a surrogate for cyanotoxin presence can overestimate risk and lead to unnecessary health advisories. In the absence of federal criteria for cyanotoxins in recreational water, the Oregon Health Authority (OHA) developed guideline values for the four most common cyanotoxins in Oregon’s fresh waters (anatoxin-a, cylindrospermopsin, microcystins, and saxitoxins). OHA developed three guideline values for each of the cyanotoxins found in Oregon. Each of the guideline values is for a specific use of cyanobacteria-affected water: drinking water, human recreational exposure and dog recreational exposure. Having cyanotoxin guidelines allows OHA to promote toxin-based monitoring (TBM) programs, which reduce the number of health advisories and focus advisories on times and places where actual, rather than potential, risks to health exist. TBM allows OHA to more efficiently protect public health while reducing burdens on local economies that depend on water recreation-related tourism. PMID:25664510

Farrer, David; Counter, Marina; Hillwig, Rebecca; Cude, Curtis

2015-01-01

395

Health-based cyanotoxin guideline values allow for cyanotoxin-based monitoring and efficient public health response to cyanobacterial blooms.  

PubMed

Human health risks from cyanobacterial blooms are primarily related to cyanotoxins that some cyanobacteria produce. Not all species of cyanobacteria can produce toxins. Those that do often do not produce toxins at levels harmful to human health. Monitoring programs that use identification of cyanobacteria genus and species and enumeration of cyanobacterial cells as a surrogate for cyanotoxin presence can overestimate risk and lead to unnecessary health advisories. In the absence of federal criteria for cyanotoxins in recreational water, the Oregon Health Authority (OHA) developed guideline values for the four most common cyanotoxins in Oregon's fresh waters (anatoxin-a, cylindrospermopsin, microcystins, and saxitoxins). OHA developed three guideline values for each of the cyanotoxins found in Oregon. Each of the guideline values is for a specific use of cyanobacteria-affected water: drinking water, human recreational exposure and dog recreational exposure. Having cyanotoxin guidelines allows OHA to promote toxin-based monitoring (TBM) programs, which reduce the number of health advisories and focus advisories on times and places where actual, rather than potential, risks to health exist. TBM allows OHA to more efficiently protect public health while reducing burdens on local economies that depend on water recreation-related tourism. PMID:25664510

Farrer, David; Counter, Marina; Hillwig, Rebecca; Cude, Curtis

2015-02-01

396

Evolution of the Freshwater Eels  

NASA Astrophysics Data System (ADS)

The freshwater anguillid eels have an unusual life history and world-wide distribution. Questions about the phylogenetic relationships of this group and how their long spawning migrations and larval phase may contribute to their global distribution have not been addressed. This paper is first presentation of molecular phylogeny of Anguilla species, and based on this phylogenetic tree we suggest new aspect of the evolution of this group. Namely, ancestral eels originated during the Eocene or earlier, in the western Pacific Ocean near present-day Indonesia. A group derived from this ancestor dispersed westward, probably by larval transport in the global circum-equatorial current through the northern edge of the Tethys Sea. This group split into the ancestor of the European and American eels, which entered into the Atlantic Ocean, and a second group, which dispersed southward and split into the east African species and Australian species. Thus the world-wide distribution of the eel family can be understood from knowledge of continental drift, ocean currents, a specialized larva and evolutionary forces favoring dispersal and speciation of segregated gene pool.

Aoyama, Jun; Tsukamoto, Katsumi

397

Persistence of Environmental DNA in Freshwater Ecosystems  

PubMed Central

The precise knowledge of species distribution is a key step in conservation biology. However, species detection can be extremely difficult in many environments, specific life stages and in populations at very low density. The aim of this study was to improve the knowledge on DNA persistence in water in order to confirm the presence of the focus species in freshwater ecosystems. Aquatic vertebrates (fish: Siberian sturgeon and amphibian: Bullfrog tadpoles) were used as target species. In control conditions (tanks) and in the field (ponds), the DNA detectability decreases with time after the removal of the species source of DNA. DNA was detectable for less than one month in both conditions. The density of individuals also influences the dynamics of DNA detectability in water samples. The dynamics of detectability reflects the persistence of DNA fragments in freshwater ecosystems. The short time persistence of detectable amounts of DNA opens perspectives in conservation biology, by allowing access to the presence or absence of species e.g. rare, secretive, potentially invasive, or at low density. This knowledge of DNA persistence will greatly influence planning of biodiversity inventories and biosecurity surveys. PMID:21858099

Dejean, Tony; Valentini, Alice; Duparc, Antoine; Pellier-Cuit, Stéphanie; Pompanon, François; Taberlet, Pierre; Miaud, Claude

2011-01-01

398

Facts about Cyanobacteria (Blue-green Algae) and Cyanobacterial Harmful Algal Blooms  

E-print Network

#12;1 Facts about Cyanobacteria (Blue-green Algae) and Cyanobacterial Harmful Algal Blooms (CyanoHABs) Cyanobacteria (blue-green algae) Cyanobacteria are bacteria and how they form Cyanobacterial blooms occur when algae that are normally present grow exuberantly

399

A function of cyanobacterial mats in phosphorus-limited tropical wetlands  

Microsoft Academic Search

Cyanobacterial mats are important components of oligotrophic wetland ecosystems in the limestone-based regions of the Caribbean. Our goals were to: (1) Estimate the biomass and primary production of cyanobacterial mats, quantify the extent of nitrogen fixation and measure the activity of alkaline phosphatase (APA) in representative marshes of northern Belize; (2) Record changes in these variables following nutrient additions. The

Eliska Rejmánková; Jaroslava Komárková

2000-01-01

400

Extinction rates in North American freshwater fishes, 1900-2010  

USGS Publications Warehouse

Widespread evidence shows that the modern rates of extinction in many plants and animals exceed background rates in the fossil record. In the present article, I investigate this issue with regard to North American freshwater fishes. From 1898 to 2006, 57 taxa became extinct, and three distinct populations were extirpated from the continent. Since 1989, the numbers of extinct North American fishes have increased by 25%. From the end of the nineteenth century to the present, modern extinctions varied by decade but significantly increased after 1950 (post-1950s mean = 7.5 extinct taxa per decade). In the twentieth century, freshwater fishes had the highest extinction rate worldwide among vertebrates. The modern extinction rate for North American freshwater fishes is conservatively estimated to be 877 times greater than the background extinction rate for freshwater fishes (one extinction every 3 million years). Reasonable estimates project that future increases in extinctions will range from 53 to 86 species by 2050.

Burkhead, Noel M.

2012-01-01