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1

The fate of the cyanobacterial toxin ?-N-methylamino-L-alanine in freshwater mussels.  

PubMed

The cyanobacterial neurotoxin, ?-N-methylamino-l-alanine (BMAA) has been suggested as a causative agent for certain neurodegenerative diseases. This cyanotoxin bioaccumulates in an array of aquatic organisms, in which it occurs as both a free amino acid and in a protein-associated form. This study was intended to investigate the environmental fate of BMAA by examining the metabolism of isotopically labeled BMAA in four freshwater mussel species. All species showed substantial uptake of BMAA from the culture media. Data showed no significant evidence for BMAA catabolism in any of the animals but did suggest metabolism via the reversible covalent modification of BMAA in freshwater mussels, a process that appears to be variable in different species. PMID:24507126

Downing, Simoné; Contardo-Jara, Valeska; Pflugmacher, Stephan; Downing, Timothy Grant

2014-03-01

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

Screening of cyanobacterial species for calcification.  

PubMed

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 HCO(3-) 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. PMID:15458316

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

2004-01-01

4

Sporadic distribution and distinctive variations of cylindrospermopsin genes in cyanobacterial strains and environmental samples from chinese freshwater bodies.  

PubMed

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; Li, Renhui

2014-09-01

5

Investigation on extracellular polymeric substances from mucilaginous cyanobacterial blooms in eutrophic freshwater lakes.  

PubMed

Enhanced knowledge on extracellular polymeric substances (EPSs) of mucilaginous cyanobacterial blooms could improve our understanding of its ecological significance. This study for the first time investigated the extraction and fractionation of EPS matrix from cyanobacterial blooms in a eutrophic freshwater lake, and the changes in chemical compositions in EPS matrix during extraction were systematically investigated by two-dimensional correlation spectroscopy (2D-COS). The analyses demonstrated that organic matters were unevenly distributed among the EPS matrix, with most of organic matters being tightly bound to cyanobacterial cells. In addition, the soluble and loosely bound EPS fractions mainly consisted of proteins, while polysaccharides became the predominant compounds in the tightly bound EPS fraction. Heating extraction at 60°C for 30min led to a high EPS yield and low cell lysis when compared with other extraction methods. The 2D-COS results revealed a preferential release of OH in polysaccharides versus amide I in proteins in the initial heating; whereas further extension of heating resulted in EPS degradation, with degradation rates arranging in a decreased order from amide I, amide II, polysaccharides-like substances to polysaccharides. These results obtained would help enhance our insights into EPS characterization from cyanobacterial blooms in eutrophic lakes. PMID:23726883

Xu, Huacheng; Yu, Guanghui; Jiang, Helong

2013-09-01

6

Macroalgal and Cyanobacterial Chemical Defenses in Freshwater Communities  

Microsoft Academic Search

Algae and cyanobacteria are important sources of primary production in freshwater systems and they figure prominently in estimates\\u000a of carbon budgets, dissolved oxygen concentration, and nutrient recycling in those habitats (Howarth et al. 1988; Schippers\\u000a et al. 2004). In recent years, these groups have garnered much negative attention as a result of their ability to dominate\\u000a aquatic systems receiving chronic

Frank A. Camacho

7

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

PubMed

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

Ibelings, Bas W; Havens, Karl E

2008-01-01

8

First detection of cyanobacterial PSP (paralytic shellfish poisoning) toxins in Spanish freshwaters.  

PubMed

Presence of the paralytic shellfish toxins (PSTs) saxitoxin, neosaxitoxin, decarbamoyl saxitoxin and gonyautoxin-5 was analyzed by mass spectrometry in 41 Spanish freshwaters and 13 strains of potential PST-producing planktonic cyanobacteria. Toxins were detected in five waterbodies, but were absent from the isolated strains. PST containing samples belonged to the same geographical region (South Western Spain) and were most likely related to the presence of the genus Aphanizomenon. PMID:21376073

Wörmer, Lars; Cirés, Samuel; Agha, Ramsy; Verdugo, María; de Hoyos, Caridad; Quesada, Antonio

2011-05-01

9

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

10

Cyanobacterial toxins: risk management for health protection  

SciTech Connect

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 45 countries, and in numerous brackish, coastal, and marine environments. The principal toxigenic genera are listed. Known sources of the families of cyanobacterial toxins (hepato-, neuro-, and cytotoxins, irritants, and gastrointestinal toxins) are briefly discussed. Key procedures in the risk management of cyanobacterial toxins and cells are reviewed, including derivations (where sufficient data are available) of tolerable daily intakes (TDIs) and guideline values (GVs) with reference to the toxins in drinking water, and guideline levels for toxigenic cyanobacteria in bathing waters. Uncertainties and some gaps in knowledge are also discussed, including the importance of exposure media (animal and plant foods), in addition to potable and recreational waters. Finally, we present an outline of steps to develop and implement risk management strategies for cyanobacterial cells and toxins in waterbodies, with recent applications and the integration of Hazard Assessment Critical Control Point (HACCP) principles.

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

2005-03-15

11

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

PubMed Central

Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a more accessible molecular identification key for its application, we generated a standard reference library of mtDNA sequences (DNA barcodes) derived from expert-identified museum specimens for 752 North American freshwater fish species. This study demonstrates that 90% of known species can be delineated using barcodes. Moreover, it reveals numerous genetic discontinuities indicative of independently evolving lineages within described species, which points to the presence of morphologically cryptic diversity. From the 752 species analyzed, our survey flagged 138 named species that represent as many as 347 candidate species, which suggests a 28% increase in species diversity. In contrast, several species of parasitic and nonparasitic lampreys lack such discontinuity and may represent alternative life history strategies within single species. Therefore, it appears that the current North American freshwater fish taxonomy at the species level significantly conceals diversity in some groups, although artificially creating diversity in others. In addition to providing an easily accessible digital identification system, this study identifies 151 fish species for which taxonomic revision is required. PMID:21670289

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

2011-01-01

12

Differential responses of eight cyanobacterial and green algal species, to carbamate insecticides.  

PubMed

In this study, five carbamate insecticides were subjected to 96 h acute toxicity tests to examine their effects on three cyanobacteria, Anabaena flos-aquae, Microcystis flos-aquae, and Mirocystis aeruginosa, and five green algae, Selenastrum capricornutun, Scenedesmus quadricauda, Scenedesmus obliquus, Chlorella vulgaris, and Chlorella pyrenoidosa. The average acute toxicity of the carbamate insecticides to the cyanobacteria and the green algae was in descending order carbaryl>carbofuran, propoxur, metolcarb > carbosulfan. Wide variations in response to the tested carbamate insecticides occurred among the eight individual species of cyanobacteria and green algae. The sensitivity of various species of algae exposed to carbofuran, propoxur, metolcarb, and carbaryl varied over one order of magnitude, and that of algae exposed to carbosulfan varied over two orders of magnitude. With regard to the diffrential sensitivity of cyanobacteria and green algae, the cyanobacteria were less sensitive than green algae to carbosulfan and propoxur. The pollutants may initiate a shift of algal group structure; especially, a shift from dominance by green algae to dominance by cyanobacteria, and may sustain cyanobacterial blooms at particular times. Therefore, the descending order of the ecosystem risk was carbosulfan > propoxur > carbofuran > carbaryl, metolcarb. There was a strong variance between toxicity and ecosystem risk; i.e., "low toxicity" does not imply "low ecosystem risk." PMID:16677910

Ma, Jianyi; Lu, Ninghai; Qin, Wendi; Xu, Ruifu; Wang, Yunbing; Chen, Xining

2006-02-01

13

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

14

Differential sensitivity of three cyanobacterial and five green algal species to organotins and pyrethroids pesticides.  

PubMed

In this work, five organotins and pyrethroids pesticides were tested to examine their effects on the three cyanobacteria Anabaena flos-aquae, Microcystis flos-aquae, Mirocystis aeruginosa and on the five green algae Selenastrum capricornutun, Scenedesmus quadricauda, Scenedesmus obliqnus, Chlorella vulgaris, Chlorella pyrenoidosa through 96 h acute toxicity tests. The results indicated that: (1) the decreasing order of the average acute toxicity to cyanobacteria and green algae of five dissimilar organotins and pyrethroids pesticides was: fentin hydroxide > cyhexatin > azocyclotin > fenbutatin oxide > beta-cyfluthrin. (2) Wide variations occurred in response to the tested pesticides among the eight individual species of cyanobacteria and green algae. The sensitivity of various species of algae exposed to fenbutatin-oxide varied over one order of magnitude, exposed to cyhexatin/fentin-hydroxide/beta-cyfluthrin varied over two orders of magnitude and exposed to azocyclotin varied three orders of magnitude. (3) In contrast with the sensitivity of cyanobacteria and green algae, cyanobacteria were much less sensitive to beta-cyfluthrin than green algae. The pollutants may result in a shift of green algal and cyanobacterial group structure, especially in a shift from dominance by green algae to dominance by cyanobacteria, and may sustain cyanobcterial blooms during the special period. Thus, the decreasing order of the aquatic ecological risk was: beta-cyfluthrin > fentin hydroxide > cyhexatin > azocyclotin > fenbutatin oxide. There was a strong variance between toxicity and ecological risk, i.e. "low toxicity" does not automatically imply "low ecological risk". The toxicity of pyrethroids pesticides was lower than that of organotins pesticides, whereas the aquatic ecological risk of pyrethroids pesticides was higher than that of organotins pesticides. PMID:15833245

Ma, Jianyi

2005-04-01

15

Structural Dynamics of Community Gene Expression In a Freshwater Cyanobacterial Bloom Over a Day-Night Cycle  

NASA Astrophysics Data System (ADS)

Cyanobacterial blooms are a major problem in eutrophic lakes and reservoirs, negatively impacting the ecology of the water body through oxygen depletion upon bloom decay and in some cases through production of toxins. Waterborne cyanobacterial toxins pose a public health threat through drinking and recreational exposure. The frequency of harmful cyanobacterial blooms (cyanoHABs) is predicted to increase due to warming regional climates (Paerl et.al, 2011) and increases in non-point source pollution due to urban expansion (Novotny, 2011). CyanoHABs represent complex consortia of cyanobacteria that live in association with diverse assemblages of heterotrophic and anoxygenic photosynthetic bacteria. A better understanding of the structure, function, and interaction between members of the complex microbial communities that support the proliferation of toxigenic cyanobacteria will improve our ability to prevent and control cyanoHABs. Studies of community gene expression, or metatranscriptomics, provide a powerful approach for quantifying changes in both the taxonomic composition (structure) and activity (function) of complex microbial systems in response to dynamic environmental conditions. We have used next-generation Illumina sequencing to characterize the metatranscriptome of a tropical eutrophic drinking water reservoir dominated by the toxigenic cyanobacterium Microcystis aeruginosa over a day/night cycle. Bacterioplankton sampling was carried out at six time points over a 24 hour period to capture variability associated with changes in the balance between phototrophic and heterotrophic activity. Total RNA was extracted and subjected to ribosomal depletion followed by cDNA synthesis and sequencing, generating 493,468 to 678,064 95-101 bp post-quality control reads per sample. Hierarchical Clustering of transcriptional profiles supported sorting of samples into two clusters corresponding to "day" and "night" collection times. Annotation of reads through the MG-RAST pipeline (Metagenomics- Rapid Annotation using Subsystem Technology) reveals that the community taxonomic composition stays relatively constant throughout the day/night cycle and is dominated by transcripts with highest identity to members of the phyla Cyanobacteria, Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes (in decreasing order) where Microcystis transcripts represent 15.3 to 25.6% of the total bacterial transcriptomes (Eave=1E-4.22). Community transcripts are enriched with genes from the photosynthesis KEGG pathway during the day. In contrast, Proteobacterial transcripts are enriched at night (20.4% of the total bacterial transcriptome compared to 14.3% in the day, p = 0.039), and reveal signatures of heterotrophic activities. Metatranscriptomic quantification of microbial community gene expression in a cyanobacterial bloom dominated by Microcystis aeruginosa contributes to a fundamental understanding of nutrient and energy cycling over a day/night cycle and will enable better management and control of these cyanoHABs. Reference: Paerl HW et.al, (2011) Sci Total Environ.409(10):1739-45. Novotny V. (2011) Journal of Water Sustainability.1(1):1-22.

Wang, J.; Fernando, S.; Thompson, J. R.

2011-12-01

16

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

17

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

PubMed

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

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

2013-03-26

18

Natural xenobiotics to prevent cyanobacterial and algal growth in freshwater: contrasting efficacy of tannic acid, gallic acid, and gramine.  

PubMed

Allelochemical action against planktonic phototrophs is one central issue in freshwater ecology and quality management. To determine some basic mechanisms of this toxic action, we exposed the coccal green alga, Desmodesmus armatus, and the coccal cyanobacterium, Microcystis aeruginosa, in a batch culture well-supplied with carbon dioxide to increasing concentrations of the polyphenols tannic acid and gallic acid and the alkaloid gramine. The phototrophs were checked after 2d and at the end of the culture for biomass-based growth rates, cell volume, maximum quantum yield of photosystem II (?PSIImax), chlorophyll a content (chla) after 2d and at the end of the culture, and lipid peroxidation only at the end of the culture. During the culture, the pH rose from 7.64 to 10.95, a pH characteristic of eutrophic freshwater bodies during nuisance algal blooms. All xenobiotics reduced the growth rate, ?PSIImax, and chla during the first 2d with M. aeruginosa being more sensitive to the polyphenols than D. armatus. The efficacy of the polyphenols declined with increasing pH, indicating potential polymerization and corresponding reduced bioavailability of the polyphenols. In contrast to the polyphenols, gramine increased its toxic action over time, independent of the prevailing pH. All exposures caused slight to severe lipid peroxidation (LPO) in the phototrophs. Hence, one mechanism of growth inhibition may be oxidative stress-mediated reduction in photosynthesis. The presented results suggest that in successful field trials with leachate, the prevailing environmental conditions may inactivate polyphenols and xenobiotics other than polyphenols may be more effective. PMID:24332729

Laue, Pauline; Bährs, Hanno; Chakrabarti, Shumon; Steinberg, Christian E W

2014-06-01

19

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

20

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

21

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

22

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

23

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

24

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

25

Supplementary Information Species Optimal N:P Freshwater/ Taxon Source  

E-print Network

Dinoflagellate 5 Dunaliella tertiolecta 12.8 Marine Chlorophyte 6, 7 Aphanizomenon gracile 13.1 Freshwater to phospho- rus limitation in batch and steady-state cultures of Dunaliella tertiolecta (Chlorophyta

26

Liquid chromatographic determination of the cyanobacterial toxin beta-n-methylamino-L-alanine in algae food supplements, freshwater fish, and bottled water.  

PubMed

Beta-N-Methylamino-L-alanine (BMAA) is a neurotoxin originally found in cycad seeds and now known to be produced by many species of freshwater and marine cyanobacteria. We developed a method for its determination in blue-green algae (BGA) food supplements, freshwater fish, and bottled water by using a strong cation-exchange, solid-phase extraction column for cleanup after 0.3 M trichloroacetic acid extraction of BGA supplements and fish. Bottled water was applied directly onto the solid-phase extraction column. For analysis of carbonated water, sonication and pH adjustment to 1.5 were needed. To determine protein-bound BMAA, the protein pellet left after extraction of the BGA supplement and fish was hydrolyzed by boiling with 6 M hydrochloric acid; BMAA was cleaned up on a C18 column and a strong cation-exchange, solid-phase extraction column. Determination of BMAA was by liquid chromatography of the fluorescent derivative formed with 9-fluorenylmethyl chloroformate. The method was validated by recovery experiments using spiking levels of 1.0 to 10 microg/g for BGA supplements, 0.5 to 5.0 microg/g for fish, and 0.002 microg/g for bottled water; mean recoveries were in the range of 67 to 89% for BGA supplements and fish, and 59 to 92% for bottled water. Recoveries of BMAA from spiked extracts of hydrolyzed protein from BGA supplements and fish ranged from 66 to 83%. The cleanup developed provides a useful method for surveying foods and supplements for BMAA and protein-bound BMAA. PMID:19722418

Scott, Peter M; Niedzwiadek, Barbara; Rawn, Dorothea F K; Lau, Ben P-Y

2009-08-01

27

Metazoan parasite species richness and genetic variation among freshwater fish species: cause or consequence?  

PubMed

The factors responsible for the maintenance of genetic variation among natural populations remain a mystery. Recent models of host-parasite co-evolution assume that parasites exert frequency-dependent selection on their hosts by favouring rare alleles that may confer resistance against infection. We tested this prediction in a comparative analysis that sought relationships between levels of genetic variation and the number of metazoan parasite species exploiting each host species. We used data on 40 species of North American freshwater fishes. After controlling for sampling effort and phylogenetic influences, we found no relationship between genetic polymorphism and parasite species richness among fish species. However, we found a marginal negative correlation between parasite species richness and heterozygosity. This result goes against the prediction that increased selective pressure by parasites should be associated with higher levels of genetic variation. Instead, it suggests that parasites may be colonising host species showing low levels of genetic variation with greater success than genetically more variable host species. PMID:10856503

Poulin, R; Marshall, L J; Spencer, H G

2000-05-01

28

Toxicity of the cyanobacterial neurotoxin beta-N-methylamino-L-alanine to three aquatic animal species.  

PubMed

Beta-N-methylamino-L-alanine (BMAA), a neurotoxin and candidate contributory cause of neurodegenerative diseases including amyotrophic lateral sclerosis, is produced by aquatic and terrestrial cyanobacteria. We have determined BMAA toxicity to three aquatic animal species: zebra fish (Danio rerio), brine shrimp (Artemia salina) and the protozoan Nassula sorex. Responses included: clonus convulsions and abnormal spinal axis formation (D. rerio), loss of phototaxis (A. salina) and mortalities (all species). These systems offer potential to further understand BMAA toxicity and the bioaccumulation and fates of BMAA in aquatic food chains leading to potential human exposure. PMID:19929735

Purdie, Esme L; Metcalf, James S; Kashmiri, Shereen; Codd, Geoffrey A

2009-01-01

29

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

30

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

31

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

32

COMPARATIVE TOXICITY OF FLUORANTHENE TO FRESHWATER AND SALTWATER SPECIES UNDER FLUORESCENT AND ULTRAVIOLET LIGHT  

EPA Science Inventory

The acute and chronic toxicity of fluoranthene was determined for a diverse group of freshwater and saltwater species under both standard laboratory fluorescent light and ultraviolet (UV) light test conditions. Acute tests with 21 species demonstrated that fluoranthene was not le...

33

A new genus and species of freshwater crab from Madagascar (Decapoda, Brachyura, Potamoidea, Potamonautidae).  

PubMed

A new genus and species of freshwater crab is described from Madagascar. The new species is morphologically closest to the three species of the genus Foza Reed & Cumberlidge, 2006, but can easily be distinguished by having a completely smooth carapace with an unarmed anterolateral margin and a mandible with a distinctly shortened anterior lobe. This unusual suite of characters is sufficient to warrant the recognition of a new monotypic genus to accommodate this species. PMID:25543766

Meyer, Kirstin S; Cumberlidge, Neil; Koppin, Jennifer C

2014-01-01

34

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

35

A new species of the freshwater fern Azolla (Azollaceae) from the Eocene Arctic Ocean  

Microsoft Academic Search

A new fossil species of the freshwater fern Azolla (Azollaceae, Salviniales) is described from an unusual setting of high palaeolatitude in the Arctic Ocean. Azolla arctica sp. nov., (lower Middle Eocene, Lomonosov Ridge) is represented by fully developed megaspore apparatuses with attached microspore massulae and clustered and dispersed microspore massulae. These abundant co-occurring fossils, combined with their associated biota, demonstrate

Margaret E. Collinson; Judith Barke; Johan van der Burgh; Johanna H. A. van Konijnenburg-van Cittert

2009-01-01

36

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...

37

hey began emerging in the late 1980s: new species of freshwater and land  

E-print Network

."Thereareverylimitedresources for turtle conservation in Asia," says James Parham of the University of California, Berkeley, the graduateT hey began emerging in the late 1980s: new species of freshwater and land turtles from. And that posed a challenge for conservation biologists, who were already struggling to protect the region

Feldman, Chris R

38

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

39

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

USGS Publications Warehouse

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

Galbraith, Heather S.

2012-01-01

40

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

41

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

PubMed Central

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 organisms for which Candidatus status is described here were isolated from freshwater lakes and ponds located in tropical, subtropical and temperate climatic zones. Phylogenetic analyses demonstrated that they are affiliated with one of the actinobacterial lineages indigenous to freshwater bacterioplankton. The seven novel taxa could only be cultivated to date as mixed cultures that also contain non-actinobacterial strains. Due to the lack of pure cultures, I propose to establish the candidate species ‘Candidatus Planktoluna difficilis’, ‘Candidatus Aquiluna rubra’, ‘Candidatus Flaviluna lacus’, ‘Candidatus Rhodoluna limnophila’, ‘Candidatus Rhodoluna planktonica’, ‘Candidatus Rhodoluna lacicola’ and ‘Candidatus Limnoluna rubra’ for these taxa. PMID:19126733

Hahn, Martin W.

2014-01-01

42

Patterns in species richness and endemism of European freshwater fish  

Microsoft Academic Search

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

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

2007-01-01

43

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

44

NOTES ON SOME FRESH-WATER FISHES FROM MAINE, DESCRIlYfIONS OF THREE NEW SPECIES.  

E-print Network

NOTES ON SOME FRESH-WATER FISHES FROM MAINE, WITH DESCRIlYfIONS OF THREE NEW SPECIES. By VVILLIAM the first-record of observations upon Maine fresh-water fishes since Holmes's publication. Prior the fresh waters of Maine have received considerable attention and a large amount of important information

45

Ionoregulatory responses to temperature change in two species of freshwater fish  

Microsoft Academic Search

We examined the ionoregulatory responses to temperature changes in two species of freshwater fish that differ in thermal preferences; the stenothermal, cold-water rainbow trout (Oncorhynchus mykiss) and the more eurythermal, warm-water common shiner (Notropis cornutus). We found that rainbow trout maintained constant plasma Na+ levels over the entire temperature regime (5–20 °C). Upon transfer from 15 °C (holding temperature) to 5 and

R. J. Gonzalez; D. G. McDonald

2000-01-01

46

Physiological responses to severe acid stress in four species of freshwater clams (unionidae)  

Microsoft Academic Search

Four species of freshwater clam,Anodonta anatina, A. cygnea, Unio pictorum, andU. tumidus were exposed for 2 weeks to acidified soft water (pH 4.0–4.5, Ca 4.6 mg\\/L) and for 4 weeks to acid in hard water conditions (Ca 18.5 mg\\/L). The exposures caused a decrease in Na+, K+, and Cl- ion and a rapid increase of Ca2+ in the hemolymph. The

K. Pynnönen

1990-01-01

47

Toxic effects of zinc on four species of freshwater fish  

NASA Astrophysics Data System (ADS)

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

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

1991-03-01

48

Chemical analysis of endolymph and the growing otolith: fractionation of metals in freshwater fish species.  

PubMed

The fractionation of metals from water to otolith is an area of research that has received relatively limited attention, especially in freshwater systems. The objectives of the present research were to study the metal partitioning between otolith and endolymph of two freshwater species: Lake trout (Salvelinus namaycush), and burbot (Lota lota). We also included the chemical analyses of water and blood from fish of the same species collected in the same area but during different years. These results provide insight regarding the partition of metals between water and fish. This is one of the first studies to provide a range of trace metal concentrations for endolymph and the growing otolith (both aragonite and vaterite) and to directly measure otolith-endolymph partition coefficients for freshwater fish. The trace elements (Mg, Sr, and Ba) most often used as otolith elemental tracers were the ones with the lowest uptake from water to blood. We found that endolymph and whole blood had similar metal concentrations, with Mg and Fe being the only elements enriched in whole blood. Results showed few significant differences in trace metal content between wild lake trout and burbot endolymph (except for K, Mg, and Ba), but significant differences existed between their aragonitic otoliths. These results suggest two different crystallization processes in these species or the presence of different proteins (and/or organic matrices) that would selectively influence elemental incorporation in the otoliths. PMID:19154085

Melancon, Sonia; Fryer, Brian J; Markham, James L

2009-06-01

49

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

50

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

51

Extraction of cyanobacterial endotoxin.  

PubMed

To simplify our efforts in acquiring toxicological information on endotoxins produced by cyanobacteria, a method development study was undertaken to identify relatively hazard-free and efficient procedures for their extraction. One article sourced and two novel methods were evaluated for their ability to extract lipopolysaccharides (LPSs) or endotoxins from cyanobacteria. The Limulus polyphemus amoebocyte lysate (LAL) assay was employed to compare the performance of a novel method utilizing a 1-butanol-water (HBW) solvent system to that of Westphal's (1965) phenol-water system (HPW) for the extraction of endotoxin from various cyanobacteria. The traditional HPW method extracted from 3- to 12-fold more endotoxin from six different cyanobacterial blooms and culture materials than did the novel HBW method. In direct contrast, the novel HBW method extracted ninefold more endotoxin from a non-microcystin producing Microcystis aeruginosa culture as compared to the HPW method. A solvent system utilizing N,N'-dimethylformamide-water (HDW) was compared to both the HPW and HBW methods for the extraction of endotoxin from natural samples of Anabaena circinalis, Microcystis flos-aquae, and a 1:1 mixture of Microcystis aeruginosa/Microcystisflos-aquae. The LAL activities of these extracts showed that the novel HDW method extracted two- and threefold more endotoxin from the Anabaena sample that did the HBW and HPW methods, respectively. The HDW method also extracted approximately 1.5-fold more endotoxin from the Microcystis flos-aquae sample as compared to both the HBW and HPW methods. On the other hand, the HBW method extracted 2- and 14-fold more endotoxin from the Microcystis flos-aquae/Microcystis aeruginosa mixture than did the HPW and HDW methods, respectively. Results of this study demonstrate that significant disparities exist between the physicochemical properties of the cell wall constituents not only of different cyanobacterial species but also of different strains of the same cyanobacterial species, as showing by the varying effectiveness of the solvent systems investigated. Therefore, a sole method cannot be regarded as universal and superior for the extraction of endotoxins from cyanobacteria. Nevertheless, the ability of the novel HBW and HDW methods to utilize easily handled organic solvents that are less hazardous than phenol render them attractive alternatives to the standard HPW method. PMID:14758595

Papageorgiou, John; Linke, Thomas A; Kapralos, Con; Nicholson, Brenton C; Steffensen, Dennis A

2004-02-01

52

The relationship of oocyte diameter and incubation temperature to incubation time in temperate freshwater fish species.  

PubMed

Based on the analysis of six egg variables and incubation temperature of 65 temperate freshwater fish species, the possible relationships between oocyte diameter, incubation time and incubation temperature were reassessed and compared to the results obtained from marine fishes. Most freshwater species have eggs (mean +/-s.d. 2.19 +/- 1.52 mm) larger than marine species, that are chiefly demersal and develop stuck to various substrata, such as plants or rocks. A strong negative relationship was found between incubation time (t, days) and incubation temperature (T, degrees C): t = 186.23e(-0.197T) (r(2)= 0.87). A strong dependence of incubation time on oocyte diameter (Ø, mm) and incubation temperature was also found and was defined as: log(10)t= 3.002 + 0.599 log(10)Ø - 1.91 log(10) (T + 2), which explained 92% of the variance of the data set. Five major groups of species were defined based on the principal component analysis (PCA) of four quantitative variables. There were two distinct groups of salmonids, displaying demersal and non-adhesive eggs with a long incubation time at low temperature, the eggs of which required a high number of degree-days. There was a large group of species possessing small, mostly demersal and adhesive eggs developing at high temperature during a short period of time, and requiring a low number of degree-days. Between these two extremes, there was a fourth group displaying intermediate values and a fifth group including three species with large, adhesive and demersal eggs incubating at high temperatures during a short period of time. The burbot Lota lota displayed an unusual combination of variables compared to the remaining species in the data set. PMID:20735585

Teletchea, F; Gardeur, J-N; Kamler, E; Fontaine, P

2009-02-01

53

Seasonal changes of freshwater ammonia-oxidizing archaeal assemblages and nitrogen species in oligotrophic alpine lakes.  

PubMed

The annual changes in the composition and abundance of ammonia-oxidizing archaea (AOA) were analyzed monthly in surface waters of three high mountain lakes within the Limnological Observatory of the Pyrenees (LOOP; northeast Spain) using both 16S rRNA and functional (ammonia monooxygenase gene, amoA) gene sequencing as well as quantitative PCR amplification. The set of biological data was related to changes in nitrogen species and to other relevant environmental variables. The whole archaeal assemblage was dominated by phylotypes closely related to the crenarchaeal 1.1a group (58% ± 18% of total 16S rRNA gene sequences), and consistent structural changes were detected during the study. Water temperature was the environmental variable that better explained spring, summer, and winter (ice-covered lakes) archaeal assemblage structure. The amoA gene was detected year round, and seasonal changes in amoA gene composition were well correlated with changes in the archaeal 16S rRNA gene pool. In addition, copy numbers of both the specific 1.1a group 16 rRNA and archaeal amoA genes were well correlated, suggesting that most freshwater 1.1a Crenarchaeota had the potential to carry out ammonia oxidation. Seasonal changes in the diversity and abundance of AOA (i.e., amoA) were better explained by temporal changes in ammonium, the substrate for nitrification, and mostly nitrite, the product of ammonia oxidation. Lacustrine amoA gene sequences grouped in coherent freshwater phylogenetic clusters, suggesting that freshwater habitats harbor typical amoA-containing ecotypes, which is different from soils and seas. We observed within the freshwater amoA gene sequence pool a high genetic divergence (translating to up to 32% amino acid divergence) between the spring and the remaining AOA assemblages. This suggests that different AOA ecotypes are adapted to different temporal ecological niches in these lakes. PMID:21239556

Auguet, Jean-Christophe; Nomokonova, Natalya; Camarero, Lluis; Casamayor, Emilio O

2011-03-01

54

Description and life-cycle of three new species of Dingularis n. g. (Digena: Plagiorchiida), parasites of Australian freshwater turtles  

Microsoft Academic Search

Dingularus n. g. is proposed to accommodate three new species, D. anfracticirrus, D. pearsoni and D. megapharynx, within the Plagiorchiida. Dingularus is closely related to the Plagiorchiidae, despite the unusual excretory systems of the three species. Adult worms were parasitic in the intestines of freshwater turtles, Chelodina expansa (D. pearsoni and D. megapharynx) and Emydura macquarii (D. anfracticirrus), and appeared

Lindsay Jue Sue; Thomas R. Platt

1999-01-01

55

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)  

Microsoft Academic Search

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

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

2005-01-01

56

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

57

New and previously described species of Dactylogyridae (Monogenoidea) from the gills of Panamanian freshwater fishes (Teleostei).  

PubMed

During an investigation of the diversity of metazoan parasites of 7 freshwater fish species from 3 localities in central Panama, the following gill dactylogyrid (Monogenoidea) species were found: Aphanoblastella chagresii n. sp. from Pimelodella chagresi (Heptapteridae); Aphanoblastella travassosi (Price, 1938) Kritsky, Mendoza-Franco, and Scholz, 2000 from Rhamdia quelen (Heptapteridae); Diaphorocleidus petrosusi n. sp. from Brycon petrosus (Characidae); Gussevia asota Kritsky, Thatcher, and Boeger, 1989, from Astronotus ocellatus (Cichlidae); Sciadicleithrum panamensis n. sp. from Aequidens coeruleopunctatus (Cichlidae); Urocleidoides flegomai n. sp. from Piabucina panamensis (Lebiasinidae); and Urocleidoides similuncus n. sp. from Poecilia gillii (Poeciliidae). Consideration of the comparative morphology and distribution of these parasites along with the evolutionary history of the host fishes suggests that diversification may be associated with geotectonic events that provided isolation of the Central American fauna with the uplift of the Panamanian Isthmus during early Pliocene (3 mya). PMID:17918354

Mendoza-Franco, Edgar F; Aguirre-Macedo, M Leopoldina; Vidal-Martínez, Victor M

2007-08-01

58

Evidence of differences in the biotransformation of organic contaminants in three species of freshwater invertebrates.  

PubMed

Acute static bioassays were performed using three freshwater invertebrate species (the oligochaete Lumbriculus variegatus, the fingernail clam Sphaerium corneum and the larvae Chironomus riparius) exposed separately to a variety of 14C radiolabelled contaminants. The aim of this work was to investigate if the chemicals remained as parent compounds after the treatments. Chemicals used were 2,4-dichlorophenol; 2,4,5-trichlorophenol; pentachlorophenol; pyrene; Fenpropidin, and Trifluralin. Homogenates of the whole body tissue of each organism were prepared and total radioactivity was measured. Contaminants were then extracted into organic solvents and analysed by high-pressure liquid chromatography techniques. Chromatograms showed that most of the substances extracted were present as parent compounds in S. corneum and in L. variegatus. In contrast, for C. riparius a low proportion of the chemicals was recovered as parent compounds. These results suggest that different metabolic processes could take place in the different species. PMID:11926182

Verrengia Guerrero, N R; Taylor, M G; Davies, N A; Lawrence, M A M; Edwards, P A; Simkiss, K; Wider, E A

2002-01-01

59

Cyanobacterial NADPH dehydrogenase complexes  

SciTech Connect

Cyanobacteria possess functionally distinct multiple NADPH dehydrogenase (NDH-1) complexes that are essential to CO2 uptake, photosystem-1 cyclic electron transport and respiration. The unique nature of cyanobacterial NDH-1 complexes is the presence of subunits involved in CO2 uptake. Other than CO2 uptake, chloroplastic NDH-1 complex has similar role as cyanobacterial NDH-1 complexes in photosystem-1 cyclic electron transport and respiration (chlororespiration). In this mini-review we focus on the structure and function of cyanobacterial NDH-1 complexes and their phylogeny. The function of chloroplastic NDH-1 complex and characteristics of plants defective in NDH-1 are also described forcomparison.

Ogawa, Teruo; Mi, Hualing

2007-07-01

60

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

61

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

PubMed

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

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

2013-07-01

62

Diversity and distribution of freshwater amphipod species in Switzerland (Crustacea: Amphipoda).  

PubMed

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

63

Reproductive investment compromises maternal health in three species of freshwater turtle.  

PubMed

Life-history theory predicts that a trade-off in the allocation of resources between different physiological systems exists because resources are finite. As a result, females investing heavily in reproduction may compromise their future health. We used hematology, serum biochemistry, mass, and morphometric measurements as indicators of physiological health state to investigate whether reproductive investment altered subsequent maternal health in three Australian freshwater turtles: the oblong turtle (Chelodina oblonga; n = 12), the Macquarie turtle (Emydura macquarii; n = 9), and the eastern long-necked turtle (Chelodina longicollis; n = 8). Maternal health was impaired in turtles that produced larger and heavier eggs and clutches. In C. oblonga and E. macquarii, increased reproductive investment generally resulted in negative changes to the hematology and serum biochemistry profile of maternal blood. Generally, increases in heterophil/lymphocyte ratio, aspartate transaminase, creatine kinase, calcium/phosphorus ratio, and albumin/globulin ratio were observed following reproduction, in addition to a decrease in glucose and total protein. These findings agree with the physiological constraint hypothesis and highlight the connection between life-history evolution and animal physiology by documenting, for the first time, how measures of physiological health state relate to reproductive investment in Australian freshwater turtles. Additionally, our findings suggest that body condition, a readily used morphological biomarker, is a poor predictor of health in turtles. Our results emphasize the need to investigate how maternal health is influenced by the reproductive process in different species. PMID:24769705

Rafferty, Anthony R; Scheelings, T Franciscus; Foley, Laura J; Johnstone, Christopher P; Reina, Richard D

2014-01-01

64

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

65

Two new species of Camallanus (Nematoda: Camallanidae) from freshwater turtles in Queensland, Australia.  

PubMed

We describe 2 new species of Camallanus (Nematoda: Camallanidae) from freshwater turtles collected in Queensland, Australia: Camallanus nithoggi n. sp. from Elseya latisternum (Gray) and Camallanus waelhreow n. sp. from Emydura krefftii (Gray), Emydura macquarrii (Gray), and Em. macquarrii dharra Cann. The only Camallanus sp. previously reported from turtles is C. chelonius Baker, 1983 (all other species in the family have been transferred to Serpinema). The 2 new species described here differ from C. chelonius in the number of male preanal papillae (7 vs. 6 in C. chelonius), the number of male postanal papillae (5 vs. 4 in C. chelonius), and the number of buccal capsule ridges. Additionally, we removed the tissues overlying the buccal capsule and used scanning electron micrographs (SEM) to show that the peribuccal shields extend laterally from the buccal capsule, the basal ring is separated from the buccal capsule by a narrow isthmus, and there is a buttress along the lateral margin of the buccal capsule that has not previously been observed in species of Camallanus. PMID:19127966

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

2008-12-01

66

Cyanosite: A Webserver for Cyanobacterial Research  

NSDL National Science Digital Library

This Web site provided by Dr. Mark Schneegurt of Wichita State University is "dedicated to information transfer within the cyanobacterial research community." The most recent version of the bibliographic database contains over 12,000 references, current through 2001. Another feature is the Toxic Cyanobacteria Home Page, which focuses on some aquatic species of cyanobacteria and the toxins that they produce.

67

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).  

PubMed

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 LC50 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. PMID:15772883

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

2005-02-01

68

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

69

Freshwater ascomycetes: Alascospora evergladensis, a new genus and species from the Florida Everglades.  

PubMed

Alascospora evergladensis, a freshwater ascomycete collected from submerged dead petioles of Nymphaea odorata during a survey of aquatic fungi along a phosphorus gradient in the Florida Everglades, is described and illustrated as a new genus and species in the Pleosporales (Pleosporomycetidae, Dothideomycetes). The new fungus is unique among genera in the Pleosporales based on a combination of morphological characters that include light brown, translucent, membranous, ostiolate ascomata with dark, amorphous material irregularly deposited on the peridium, especially around the ostiole; globose, fissitunicate, thick-walled asci; septate pseudoparaphyses; and 1-septate ascospores that are hyaline when young, and surrounded by a hyaline gelatinous sheath that is wing-shaped in outline on each side of the ascospore. The sheath is distinctive in that it first expands in water and is translucent, then condenses and darkens around older ascospores, giving them a dark brown, verruculose appearance. PMID:20120226

Raja, Huzefa A; Violi, Helen A; Shearer, Carol A

2010-01-01

70

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

Microsoft Academic Search

Sulfur pollution can lead to serious problems in freshwater wetlands, including phosphorus eutrophication and sulfide toxicity. We tested the effects of anaerobic iron-rich groundwater discharge in fens, simulated by iron injection, on two characteristic species (Juncus effusus and Caltha palustris) in a sulfidic environment. Biomass production of C. palustris roots showed an optimum response to the combined addition of iron

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

2007-01-01

71

Analysis of rDNA Regions of Five Freshwater Unionid Mussel Species in Presque Isle Bay, Southeastern Lake Erie  

Microsoft Academic Search

Population structure and fecundity of freshwater mussels can be difficult to assess due to the benthic habitat and complex life cycles of these organisms. However, rapid and reliable classification of unionids can be accomplished with polymerase chain reaction if species-specific DNA primers are established. In this report we describe the sequence analysis of the ITS1 and ITS2 regions from five

Trevor J. Manendo; Michael A. Campbell; Herbert H. Gilroy; Edwin C. Masteller

2008-01-01

72

Mercury and selenium concentrations in muscle tissue of different species of predatory freshwater fish and correlation between these elements  

Microsoft Academic Search

Concentrations of total mercury and selenium were determined in 49 and 42 muscle tissue samples, respectively, of six species of predatory freshwater fish, dace (Leuciscus leuciscus), pike perch (Sander lucioperca), pike (Esox lucius), European catfish (Silurus glanis), rainbow trout (Oncorhynchus mykiss) and asp (Aspius aspius). Muscle selenium concentration did not correlate with the corresponding total mercury concentration (R

Imrich Strapá?; Jozef Sokol; Daniel Žatko; Mária Baranová

2012-01-01

73

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

74

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

75

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

76

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

PubMed

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

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

2011-12-01

77

Plant-associated bacterial populations on native and invasive plant species: comparisons between 2 freshwater environments.  

PubMed

Plant-microbial interactions have been well studied because of the ecological importance of such relationships in aquatic systems. However, general knowledge regarding the composition of these biofilm communities is still evolving, partly as a result of several confounding factors that are attributable to plant host properties and to hydrodynamic conditions in aquatic environments. In this study, the occurrences of various bacterial phylogenetic taxa on 2 native plants, i.e., mayapple (Podophyllum peltatum L.) and cow parsnip (Heracleum maximum Bartram), and on an invasive species, i.e., garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande), were quantitatively examined using nucleic acid staining and fluorescence in situ hybridization. The plants were incubated in triplicates for about a week within the Kalamazoo River and Pierce Cedar Creek as well as in microcosms. The bacterial groups targeted for enumeration are known to globally occur in relatively high abundance and are also ubiquitously distributed in freshwater environments. Fluorescence in situ hybridization analyses of the bacterioplankton assemblages revealed that the majority of bacterial cells that hybridized with the different probes were similar between the 2 sites. In contrast, the plant-associated populations while similar on the 3 plants incubated in Kalamazoo River, their representations were highest on the 2 native plants relative to the invasive species in Pierce Cedar Creek. Overall, our results further suggested that epiphytic bacterial assemblages are probably under the influences of and probably subsequently respond to multiple variables and conditions in aquatic milieus. PMID:22625420

Olapade, Ola A; Pung, Kayleigh

2012-06-01

78

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

79

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

80

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

PubMed

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

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

2011-01-01

81

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

82

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

83

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

84

Involvement of caspase and reactive oxygen species in cyanobacterial toxin anatoxin-a-induced cytotoxicity and apoptosis in rat thymocytes and Vero cells  

Microsoft Academic Search

. The hepatotoxins and neurotoxins produced by bloom-forming cyanobacteria have been the cause of human and animal health hazards and even death. The most common cyanobacterial neurotoxin is anatoxin-a, and intoxications by these toxins can be fatal through muscular paralysis causing respiratory arrest. We report here anatoxin-a-induced apoptosis in two non-neuronal cells, viz. cultured rat thymocytes and African green monkey

P. V. Lakshmana Rao; R. Bhattacharya; Nidhi Gupta; M. M. Parida; A. S. B. Bhaskar; Rupa Dubey

2002-01-01

85

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

86

Characterizing a hybrid zone between a cryptic species pair of freshwater snails.  

PubMed

Characterizing hybrid zones and their dynamics is a central goal in evolutionary biology, but this is particularly challenging for morphologically cryptic species. The lack of conspicuous divergence between parental types means intermediate hybrid forms often go undetected. We aimed to detect and characterize a suspected hybrid zone between a pair of morphologically cryptic lineages of the freshwater snail, Radix. We sampled Radix from across a contact zone between two mitochondrial lineages (Radix balthica and an undescribed lineage termed 'MOTU3') and detected admixture between two nuclear genotype clusters, which were significantly but not categorically associated with the mitochondrial lineages. Using a model selection approach, we show that the admixture cline is best explained by an interaction between precipitation and temperature gradients over the area, rather than geographic distance. We thus hypothesize that the correlation with climatic gradients suggests environmental selection has played a role in maintaining the hybrid zone. In a 2050 climate change scenario, we furthermore predict an expansion of one of the nuclear clusters and a widening of the hybrid zone as the climate warms and dries. PMID:25533031

Patel, Simit; Schell, Tilman; Eifert, Constanze; Feldmeyer, Barbara; Pfenninger, Markus

2015-02-01

87

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

88

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

89

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

90

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

Microsoft Academic Search

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

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

1993-01-01

91

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

92

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

93

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

94

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

95

Cyanobacterial hydrogen production  

Microsoft Academic Search

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

Datta Madamwar; Nikki Garg; Vishal Shah

2000-01-01

96

Zooplankton, fish and fisheries in tropical freshwaters  

Microsoft Academic Search

About 40% of all fish species occur in freshwater, although only 1% of the globe is occupied by freshwaters. The tropics harbour a high percentage of these fishes. Freshwater zooplankton on the other hand is far less diverse than its marine counterpart and the tropics do not harbour a markedly high percentage of freshwater species either. The antecedents of freshwater

C. H. Fernando

1994-01-01

97

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

98

The freshwater planarian Polycelis felina as a sensitive species to assess the long-term toxicity of ammonia.  

PubMed

Behavioural endpoints are a good link between physiological and ecological effects. However long-term behavioural endpoints are not uniformly studied over all different organism groups. For example behaviour has been scarcely studied in planarians. Unionized ammonia (NH(3)) is one of the most widespread pollutants in developed countries, and is known to alter animal behaviour. In this study a long-term (30 d) bioassay was conducted to assess the effect of this pollutant on survival and behavioural activity (e.g. locomotion activity) of the freshwater planarian Polycelis felina. One control and three environmentally-realistic concentrations of unionized ammonia (treatments of 0.02, 0.05, and 0.09 mg N-NH(3) L(-1)) were used in quintuplicate. The behaviour of planarians was measured after 0, 10, 20 and 30 d of ammonia exposure. Mortality was recorded every 2 d. Unionized ammonia increased mortality in the two highest NH(3) concentrations and the locomotory activity was depressed in all treatments after 20 d of exposure. Behavioural effect was observed at concentrations 20 times lower than the short-term LC50 for this species. Previous studies proposed safe concentrations of unionized ammonia of 0.01-0.10 mg N-NH(3) L(-1) to aquatic ecosystems, but our study has shown that these concentrations will affect planarians. Because planarians play a key role in streams (as predator/scavenger), safe concentrations should be below 0.02 mg N-NH(3) L(-1) to protect this species in the freshwater community. Our results can contribute to improve the knowledge about ammonia toxicity to freshwater ecosystems, we recommend that safe concentrations of unionized ammonia should be based on very sensitive species. PMID:21546058

Alonso, Alvaro; Camargo, Julio A

2011-07-01

99

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

100

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

101

Mercury and selenium concentrations in muscle tissue of different species of predatory freshwater fish and correlation between these elements.  

PubMed

Concentrations of total mercury and selenium were determined in 49 and 42 muscle tissue samples, respectively, of six species of predatory freshwater fish, dace (Leuciscus leuciscus), pike perch (Sander lucioperca), pike (Esox lucius), European catfish (Silurus glanis), rainbow trout (Oncorhynchus mykiss) and asp (Aspius aspius). Muscle selenium concentration did not correlate with the corresponding total mercury concentration (R² < 0.198) in all examined predatory fish species. There was an inverse correlation between the ratio Se/Hg content and the total mercury content in the muscle tissues of dace, pike perch, pike, European catfish and asp. The muscle tissue of rainbow trout exhibits a linear correlation between the ratio Se/Hg content and the total mercury content. The total mercury concentration of all examined samples did not exceed the hygienic limit for Hg for predatory fish. PMID:24779785

Strapá?, Imrich; Sokol, Jozef; Žatko, Daniel; Baranová, Mária

2012-01-01

102

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

103

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

NASA Astrophysics Data System (ADS)

In the Iberian Peninsula the European pond turtle ( Emys orbicularis) and the Mediterranean pond turtle ( Mauremys leprosa) share many freshwater habitats, in particular Mediterranean streams. Whether and how these two species divide space within those habitats is poorly known in part due to the very low abundance of E. orbicularis at most syntopic sites. The spatial coexistence of these two species was studied along a 1.3 km reach of a typical Mediterranean stream based on data from trapping sessions and basking counts. The effect of the hydrological regime on differences in space use between species was also assessed. Spatial associations between species and between each species and microhabitat descriptors were estimated using a permutation procedure to account for spatial autocorrelation. Differences in the use of space were also estimated using a resample technique to account for the small sample sizes of E. orbicularis. Results indicate that E. orbicularis shows a preference for temporary, shallow, well vegetated and sandy reaches, while M. leprosa is less selective regarding microhabitat. Differences between E. orbicularis and juveniles of M. leprosa were less obvious. The high spatial heterogeneity of Mediterranean streams may be responsible for the persistence of viable populations of E. orbicularis as well as favouring the coexistence of the two turtle species. Therefore, stream habitat management and conservation plans for E. orbicularis should give priority to the maintenance of high levels of heterogeneity along Mediterranean streams.

Segurado, Pedro; Figueiredo, Diogo

2007-09-01

104

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

105

Molecular Analysis of the Freshwater Prawn Macrobrachium olfersii (Decapoda, Palaemonidae) Supports the Existence of a Single Species throughout Its Distribution  

PubMed Central

Macrobrachium olfersii is an amphidromous freshwater prawn, widespread along the eastern coasts of the Americas. This species shows great morphological modifications during ontogenesis, and several studies have verified the existence of a wide intraspecific variation. Because of this condition, the species is often misidentified, and several synonyms have been documented. To elucidate these aspects, individuals of M. olfersii from different populations along its range of distribution were investigated. The taxonomic limit was established, and the degree of genetic variability of this species was described. We extracted DNA from 53 specimens of M. olfersii, M. americanum, M. digueti and M. faustinum, which resulted in 84 new sequences (22 of 16S mtDNA, 45 of Cythocrome Oxidase I (COI) mtDNA, and 17 of Histone (H3) nDNA). Sequences of three genes (single and concatenated) from these species were used in the Maximum Likelihood and Bayesian Inference phylogenetic analyses and COI sequences from M. olfersii were used in population analysis. The genetic variation was evaluated through the alignment of 554 bp from the 16S, 638 bp from the COI, and 338 bp from the H3. The rates of genetic divergence among populations were lower at the intraspecific level. This was confirmed by the haplotype net, which showed a continuous gene flow among populations. Although a wide distribution and high morphological intraspecific variation often suggest the existence of more than one species, genetic similarity of Caribbean and Brazilian populations of M. olfersii supported them as a single species. PMID:23382941

Rossi, Natália; Mantelatto, Fernando Luis

2013-01-01

106

Molecular analysis of the freshwater prawn Macrobrachium olfersii (Decapoda, Palaemonidae) supports the existence of a single species throughout its distribution.  

PubMed

Macrobrachium olfersii is an amphidromous freshwater prawn, widespread along the eastern coasts of the Americas. This species shows great morphological modifications during ontogenesis, and several studies have verified the existence of a wide intraspecific variation. Because of this condition, the species is often misidentified, and several synonyms have been documented. To elucidate these aspects, individuals of M. olfersii from different populations along its range of distribution were investigated. The taxonomic limit was established, and the degree of genetic variability of this species was described. We extracted DNA from 53 specimens of M. olfersii, M. americanum, M. digueti and M. faustinum, which resulted in 84 new sequences (22 of 16S mtDNA, 45 of Cythocrome Oxidase I (COI) mtDNA, and 17 of Histone (H3) nDNA). Sequences of three genes (single and concatenated) from these species were used in the Maximum Likelihood and Bayesian Inference phylogenetic analyses and COI sequences from M. olfersii were used in population analysis. The genetic variation was evaluated through the alignment of 554 bp from the 16S, 638 bp from the COI, and 338 bp from the H3. The rates of genetic divergence among populations were lower at the intraspecific level. This was confirmed by the haplotype net, which showed a continuous gene flow among populations. Although a wide distribution and high morphological intraspecific variation often suggest the existence of more than one species, genetic similarity of Caribbean and Brazilian populations of M. olfersii supported them as a single species. PMID:23382941

Rossi, Natália; Mantelatto, Fernando Luis

2013-01-01

107

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

108

Temporal shifts in cyanobacterial communities at different sites on the Nakdong River in Korea.  

PubMed

The studies of cyanobacterial blooms resulting from eutrophication or climate change and investigation of changes in the cyanobacterial community in freshwater environments are critical for the management of drinking water. Therefore, we investigated the cyanobacterial communities at 6 sites along the Nakdong River in South Korea from May 2012 to October 2012 by using high-throughput sequencing techniques and studied their relationship with various geochemical factors at sampling sites. Diverse genera (total of 175 genera) were detected within the cyanobacteria, and changes in their compositions were analyzed. The genus Prochlorococcus predominated in the May samples, especially in those obtained from the upstream part of the river, whereas the relative abundance of Microcystis and Anabaena increased with increase in water temperature. The relationship between the cyanobacterial community and environmental factors was analyzed by canonical correlation analysis, and the correlation between harmful cyanobacteria and chemical factors was analyzed by nonmetric multidimensional scaling ordination. Various environmental factors such as dissolved oxygen, pH, electric conductivity, temperature were found to affect the cyanobacterial communities in the river. The results of this study could help in the management of freshwater environments and in maintenance of drinking water quality. PMID:24169512

Hur, Moonsuk; Lee, Injung; Tak, Bo-Mi; Lee, Hae Jin; Yu, Jae Jeong; Cheon, Se Uk; Kim, Bong-Soo

2013-12-01

109

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

110

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

111

Conserving Madagascar's Freshwater Biodiversity  

NSDL National Science Digital Library

This peer-reviewed article from BioScience is about conserving freshwater diversity in Madagascar. The island nation of Madagascar, an international conservation priority, is now also recognized as a global hotspot for freshwater biodiversity. Three emerging characteristics of Madagascar's threatened freshwater biota deserve increased attention from the scientific and conservation communities. First, species richness is not low, as was once assumed for both the freshwater fishes and the invertebrates. Second, many species are restricted to a specific region or even to single river basins. Often these species are also limited to streams or rivers draining primary forest habitat. Finally, many of the island's freshwater fishes are basal taxa, having diverged earlier than any other extant members of their clade. As such, these taxa assume disproportional phylogenetic importance. In the face of ongoing environmental threats, links among microendemism, forest stream specialization, and basal phylogenetic position highlight the importance and vulnerability of these species and provide a powerful incentive for immediate conservation action.

JONATHAN P. BENSTEAD, PATRICK H. DE RHAM, JEAN-LUC GATTOLLIAT, FRANÃ?OIS-MARIE GIBON, PAUL V. LOISELLE, MICHEL SARTORI, JOHN S. SPARKS, and MELANIE L. J. STIASSNY (; )

2003-11-01

112

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

113

A histoenzymological investigation of the caudal neurosecretory system in six species of freshwater teleosts: a comparative study.  

PubMed

Enzymecytochemical features of the caudal neurosecretory system of 6 species of freshwater teleosts, Gudusia chapra, Gonialosa manmina (Clupeidae, Clupeiformes), Oxygaster bacaila (Cyprinidae, Cypriniformes), Mystus bleekeri (Bagridae, Cypriniformes), Sciaena coiter (Scienidae, Perciformes), and Mastacembelus pancalus (Mastacembelidae, Mastacembeliformes) have been investigated with the help of several specific histochemical techniques. No sex-dependent variation have been observed in the enzymecytochemical characteristics of the caudal neurosecretory system of the present species. The Dahlgren cells show intense RNA activity. Caudal neurosecretion lacks carbohydrate but seems to possess small amount of lipid. Acid-phosphatase is located in the Dahlgren cells and axons. Alkaline-phosphatase has been observed in the Dahlgren cells, axons, and urophysial blood-capillaries. Acetylcholine esterase is present in the Dahlgren cells, axons, and urophysis of Mystus, Mastacembelus, and Gonialosa, but lacking in the other 3 species. It is concluded that the caudal neurosecretory system of Mystus, Mastacembelus, and Gopialosa is innervated by cholinergic neurons. Despite their different taxonomic positions, caudal neurosecretory system of all 6 species produce similar responses to various enzymecytochemical tests, except for acetylcholine esterase. PMID:2591699

Pandey, A C

1989-01-01

114

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

PubMed

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

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

2007-05-01

115

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

116

Variability of fatty acid components of marine and freshwater gastropod species from the littoral zone of the Red Sea, Mediterranean Sea, and Sea of Galilee  

Microsoft Academic Search

Eight marine gastropod species from the littoral zone of the Red and Mediterranean Seas, and four freshwater gastropods from the Sea of Galilee were analysed for their fatty acid composition using TLC (silver nitrate impregnated silica gel) and gas chromatography–mass spectrometry (GC\\/MS). The major fatty acid components in all twelve samples were polyunsaturated fatty acids (PUFA). The total lipids of

J. V Go; T ?ezanka; m Srebnik; V. M Dembitsky

2002-01-01

117

Phylogeny and biogeography of highly diverged freshwater fish species (Leuciscinae, Cyprinidae, Teleostei) inferred from mitochondrial genome analysis.  

PubMed

The distribution of freshwater taxa is a good biogeographic model to study pattern and process of vicariance and dispersal. The subfamily Leuciscinae (Cyprinidae, Teleostei) consists of many species distributed widely in Eurasia and North America. Leuciscinae have been divided into two phyletic groups, leuciscin and phoxinin. The phylogenetic relationships between major clades within the subfamily are poorly understood, largely because of the overwhelming diversity of the group. The origin of the Far Eastern phoxinin is an interesting question regarding the evolutionary history of Leuciscinae. Here we present phylogenetic analysis of 31 species of Leuciscinae and outgroups based on complete mitochondrial genome sequences to clarify the phylogenetic relationships and to infer the evolutionary history of the subfamily. Phylogenetic analysis suggests that the Far Eastern phoxinin species comprised the monophyletic clades Tribolodon, Pseudaspius, Oreoleuciscus and Far Eastern Phoxinus. The Far Eastern phoxinin clade was independent of other Leuciscinae lineages and was closer to North American phoxinins than European leuciscins. All of our analysis also suggested that leuciscins and phoxinins each constituted monophyletic groups. Divergence time estimation suggested that Leuciscinae species diverged from outgroups such as Tincinae to be 83.3 million years ago (Mya) in the Late Cretaceous and leuciscin and phoxinin shared a common ancestor 70.7 Mya. Radiation of Leuciscinae lineages occurred during the Late Cretaceous to Paleocene. This period also witnessed the radiation of tetrapods. Reconstruction of ancestral areas indicates Leuciscinae species originated within Europe. Leuciscin species evolved in Europe and the ancestor of phoxinin was distributed in North America. The Far Eastern phoxinins would have dispersed from North America to Far East across the Beringia land bridge. The present study suggests important roles for the continental rearrangements during the Late Cretaceous to form the present-day distribution of organisms. Furthermore, the Late Cretaceous biotic turnover influenced for the modern terrestrial biodiversity. PMID:23174367

Imoto, Junichi M; Saitoh, Kenji; Sasaki, Takeshi; Yonezawa, Takahiro; Adachi, Jun; Kartavtsev, Yuri P; Miya, Masaki; Nishida, Mutsumi; Hanzawa, Naoto

2013-02-10

118

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

119

Assessment of cylindrospermopsin toxin in an arid Saudi lake containing dense cyanobacterial bloom.  

PubMed

This study reports the presence of the cyanobacterial toxin cylindrospermopisn (CYN) and its producer Cylindrospermopsis raciborskii for the first time in Saudi freshwater sources. C. raciborskii was found in Gazan Dam Lake water with two morphotypes (coiled and straight). The appearance and cell density of this species was significantly positively related to high temperature and high ammonium concentrations, and negatively with nitrate and phosphate concentrations in the lake. Intracellular concentrations of CYN (4-173 ?g L(-1)) were associated with C. raciborskii rather than other cyanobacteria with a maximal value obtained in June 2011, coinciding with the highest bloom of this species (19?×?10(7) trichome L(-1)). CYN cell quotas (0.6-14.6 pg cell(-1)) varied significantly along the study period and correlated with most environmental factors. The results of ELISA and liquid chromatography-mass spectrometry proved that the CYN production by strains of this species was isolated from this lake during the present study, with an amount reaching 568 ?g g(-1). Extracellular CYN was also detected in cell-free lake water at concentrations 0.03-23.3 ?g L(-1), exceeding the drinking water guideline value of 1 ?g L(-1) during the Apr-Jul period. As this lake is an important source for drinking and irrigation waters, CYN monitoring should be included in the environmental and health risk assessment plans of these water bodies. PMID:22628106

Mohamed, Zakaria A; Al-Shehri, Abdulrahman M

2013-03-01

120

Biodiversity of freshwater fungi  

Microsoft Academic Search

There are more than 600 species of freshwater fungi with more known from temperate, as compared to tropical regions. These includeca 340 ascomycetes, 300 deuteromycetes, and a number of lower fungi which are not discussed here.Aniptodera, Annulatascus, Massarina, Ophioceras andPseudohalonectria are common freshwater ascomycetes, which appear to be well adapted for this lifestyle either in their ascospore types or their

T K Goh; K D Hyde

1996-01-01

121

A Cyanobacterial Circadian Clockwork  

PubMed Central

Cyanobacteria have become a major model system for analyzing clock phenomena. The temporal program in this organism enhances fitness in rhythmic environments and is truly global—essentially all genes are regulated by the circadian system. The topology of the chromosome also oscillates and possibly regulates the rhythm of gene expression. The underlying circadian mechanism appears to consist of both a post-translational oscillator (PTO) and a transcriptional/translational feedback loop (TTFL). The PTO can be reconstituted in vitro with three purified proteins (KaiA, KaiB, and KaiC) and ATP. These three core oscillator proteins have been crystallized and structurally determined, the only full-length circadian proteins to be so characterized. The timing of cell division is gated by a circadian checkpoint, but the circadian pacemaker is not influenced by the status of the cell division cycle. This imperturbability may be due to the presence of the PTO that persists under conditions in which metabolism is repressed. Recent biochemical, biophysical, and structural discoveries bring the cyanobacterial circadian system to the brink of explaining heretofore unexplainable biochemical characteristics of a circadian oscillator: the long time constant, precision, and temperature compensation. PMID:18786387

Johnson, Carl Hirschie; Mori, Tetsuya; Xu, Yao

2008-01-01

122

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...

123

Tardigrades from Signy Island, South Orkney Islands, with particular reference to freshwater species  

Microsoft Academic Search

Seventeen species of Tardigrada from lakes and catchments on Signy Island, South Orkney Islands, are described. Two species, Echiniscus punctus and Isohypsibius laevis are new to science, and two, Oreella minor and Pseudechiniscus suillus, are new to the Signy Is. records.

S. J. McInnes

1995-01-01

124

The first troglobitic species of freshwater flatworm of the suborder Continenticola (Platyhelminthes) from South America  

PubMed Central

Abstract Brazilian cave diversity, especially of invertebrates, is poorly known. The Bodoquena Plateau, which is located in the Cerrado Biome in central Brazil, has approximately 200 recorded caves with a rich system of subterranean water resources and high troglobitic diversity. Herein we describe a new troglobitic species of Girardia that represents the first obligate cave-dwelling species of the suborder Continenticola in South America. Specimens of the new species, which occur in a limestone cave in the Bodoquena Plateau, in the Cerrado biome, are unpigmented and eyeless. Species recognition in the genus Girardia is difficult, due to their great morphological resemblance. However, the new species can be easily recognized by a unique feature in its copulatory apparatus, namely a large, branched bulbar cavity with multiple diverticula. PMID:25632242

de Souza, Stella Teles; Morais, Ana Laura Nunes; Cordeiro, Lívia Medeiros; Leal-Zanchet, Ana Maria

2015-01-01

125

The first troglobitic species of freshwater flatworm of the suborder Continenticola (Platyhelminthes) from South America.  

PubMed

Brazilian cave diversity, especially of invertebrates, is poorly known. The Bodoquena Plateau, which is located in the Cerrado Biome in central Brazil, has approximately 200 recorded caves with a rich system of subterranean water resources and high troglobitic diversity. Herein we describe a new troglobitic species of Girardia that represents the first obligate cave-dwelling species of the suborder Continenticola in South America. Specimens of the new species, which occur in a limestone cave in the Bodoquena Plateau, in the Cerrado biome, are unpigmented and eyeless. Species recognition in the genus Girardia is difficult, due to their great morphological resemblance. However, the new species can be easily recognized by a unique feature in its copulatory apparatus, namely a large, branched bulbar cavity with multiple diverticula. PMID:25632242

de Souza, Stella Teles; Morais, Ana Laura Nunes; Cordeiro, Lívia Medeiros; Leal-Zanchet, Ana Maria

2015-01-01

126

The Freshwater Mussel (Elliptio complanata) as a Sentinel Species: Vitellogenin and Steroid Receptors.  

PubMed

Freshwater mussels, Elliptio complanata were collected from a reference and pollutant-impacted pond on Cape Cod, MA. Glutathione-S-transferase (GST) activity was measured in gill, hepatopancreas and foot. In addition, content of seven heavy metals were measured in whole bodies. GST activity was significantly elevated in hepatopancreas and foot, as was whole body cadmium level in animals from the contaminated site suggesting that these animals have been exposed to organic and inorganic contaminants. Sodium dodecyl acrylamide gel electrophoresis (SDS-PAGE) analysis showed putative vitellogenins with molecular weight 180 and 205 kDa bands only in the ovary. In non-denatured gel electrophoresis ovarian extracts revealed two higher molecular weight bands at 550 and 700 kDa, which were reproductive stage specific. Western blotting of SDS-PAGE and non-denatured gels using the anti-scallop yolk-protein antibody confirmed the presence of cross-reacting bands of the same molecular weights in the ovary but not other tissues. Although several experiments involving steroid hormone exposure were done, no significant changes in vitellogenin protein levels were observed. However, using an anti-human ER? antibody, ER? positive bands were observed both in female foot, and the ovary. No cross reactivity with the antibody was observed in hepatopancreas. Additional studies are required to resolve questions of vitellogenin regulation and the role of (xeno)estrogens in bivalve molluscs. PMID:21676747

Won, Seung-Jae; Novillo, Apolonia; Custodia, Noemi; Rie, Melanie T; Fitzgerald, Kelly; Osada, Makoto; Callard, Ian P

2005-01-01

127

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

128

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

129

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

PubMed Central

In order to understand and protect ecosystems, local gene pools need to be evaluated with respect to their uniqueness. Cryptic species present a challenge in this context because their presence, if unrecognized, may lead to serious misjudgement of the distribution of evolutionarily distinct genetic entities. In this study, we describe the current geographical distribution of cryptic species of the ecologically important stream amphipod Gammarus fossarum (types A, B and C). We use a novel pyrosequencing assay for molecular species identification and survey 62 populations in Switzerland, plus several populations in Germany and eastern France. In addition, we compile data from previous publications (mainly Germany). A clear transition is observed from type A in the east (Danube and Po drainages) to types B and, more rarely, C in the west (Meuse, Rhone, and four smaller French river systems). Within the Rhine drainage, the cryptic species meet in a contact zone which spans the entire G. fossarum distribution range from north to south. This large-scale geographical sorting indicates that types A and B persisted in separate refugia during Pleistocene glaciations. Within the contact zone, the species rarely co-occur at the same site, suggesting that ecological processes may preclude long-term coexistence. The clear phylogeographical signal observed in this study implies that, in many parts of Europe, only one of the cryptic species is present. PMID:21909373

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

2011-01-01

130

A proposal for the unification of five species of the cyanobacterial genus Microcystis Kützing ex Lemmermann 1907 under the rules of the Bacteriological Code.  

PubMed

Genomic DNA homologies were examined from six Microcystis (cyanobacteria) strains, including five different species, Microcystis aeruginosa, Microcystis ichthyoblabe, Microcystis novacekii, Microcystis viridis and Microcystis wesenbergii. All DNA-DNA reassociation values between two strains of M. aeruginosa and the other four species exceeded 70%, which is considered high enough for them to be classified within the same bacterial species. It is proposed to unify these five species into M. aeruginosa under the Rules of the Bacteriological Code and NIES843T (= IAM M-247T) is proposed as the type strain. Two other species, Microcystis flos-aquae and Microcystis pseudofilamentosa, should be regarded as morphological variations of this unified M. aeruginosa. The current taxonomy of cyanobacteria depends too much upon morphological characteristics and must be reviewed by means of bacteriological methods as well as traditional botanical methods. PMID:11411709

Otsuka, S; Suda, S; Shibata, S; Oyaizu, H; Matsumoto, S; Watanabe, M M

2001-05-01

131

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

132

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...

133

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...

134

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

135

early 800 native fish species in 36 families inhabit the freshwater rivers, streams, and  

E-print Network

four times as many fish species as the western states, yet the Southwestern deserts have a remarkable link in the food chain, feeding on insects and serving as prey for sport fishes, birds, and other for dissolved oxygen, support, food, and shelter. Marine mammals (whales, dol- phins, seals, sea otters

Liskiewicz, Maciej

136

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

137

Variable survival across low pH gradients in freshwater fish species.  

PubMed

A series of 14 day experiments was conducted on five common New Zealand fish species (redfin bully Gobiomorphus huttoni, inanga Galaxias maculatus, brown trout Salmo trutta, longfin eel Anguilla dieffenbachii and koaro Galaxias brevipinnis) to assess the effect of pH on survival and changes in body mass. No species survived in water of pH <4 although there was 100% survival of all adults at pH 4.5, G. maculatus larvae were also tested and had high mortality at this pH. Results suggest that adults are tolerant of low-pH waters; however, successful remediation of anthropogenically acidified streams will require an understanding of the susceptibility to low pH on different life cycle stages. PMID:25230112

Jellyman, P G; Harding, J S

2014-11-01

138

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

139

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

140

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

141

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

142

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

143

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

144

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

145

ESTIMATION OF TOXICITY TO MARINE SPECIES WITH STRUCTURE-ACTIVITY MODELS DEVELOPED TO ESTIMATE TOXICITY TO FRESHWATER FISH  

EPA Science Inventory

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

146

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

SciTech Connect

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

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

1996-02-01

147

Transgenic plants with cyanobacterial genes  

Microsoft Academic Search

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

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

2009-01-01

148

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)

149

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

150

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

151

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

152

ECOSYSTEM EFFECTS OF CYANOBACTERIAL HARMFUL ALGAL BLOOMS  

EPA Science Inventory

Harmful cyanobacterial blooms represent one of the most serious ecological stressors in lakes, rivers, estuaries and marine environments. When there are persistent or frequent blooms with high biomass of cyanobacterial cells, colonies or filaments in the water, a wide range of i...

153

Commensal Pseudomonas Species Isolated from Wastewater and Freshwater Milieus in the Eastern Cape Province, South Africa, as Reservoir of Antibiotic Resistant Determinants  

PubMed Central

Pseudomonas species are opportunistic pathogens with implications in a wide range of diseases including cystic fibrosis and sickle cell anaemia. Because of their status as multidrug resistant (MDR) and extremely drug resistant (XDR) bacteria Pseudomonas species represent a threat to public health. Prevalence, antibiogram and associated antibiotic resistant genes of Pseudomonas species isolated from freshwater and mixed liquor environments in the Eastern Cape Province of South Africa were assessed. Polymerase chain reaction (PCR) based technique was used to identify the isolates and screen for antibiotic resistant genes. The result shows occurrence of Pseudomonas spp. in freshwater and mixed liquor as follows: 71.42% and 37.5% (P. putida), 14.28% and 31.25% (P. flourescens), 7.14% and 6.25% (P. aeruginosa) and 7.14% and 25% for other Pseudomonas species respectively. Disk diffusion antibiogram of the Pseudomonas isolates from the two locations showed 100% resistance to penicillin, oxacillin, clindamycin, rifampicin and 100% susceptibility to ciprofloxacin and gentamicin with varied percentage resistances to cephalothin, nalidixic acid, tetracycline, and ampicillin. The blaTEM antibiotic resistant gene was detected in 12.5% of P. putida, 57.14% of P. fluorescens, 100% P. aeruginosa and 40% in other Pseudomonas species. Similarly, Integrons conserved segment were detected in 12.5% of P. putida, 57.14% of P. fluorescens, 100% of P. aeruginosa and 40% of other Pseudomonas species. The presence of blaTEM gene and integrons conserved segment in some of the isolates is worrisome and suggest Pseudomonas species as important reservoirs of multidrug resistance genes in the Eastern Cape Province environment. PMID:22851958

Igbinosa, Isoken H.; Nwodo, Uchechukwu U.; Sosa, Anibal; Tom, Mvuyo; Okoh, Anthony I.

2012-01-01

154

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

155

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

156

Cyanobacterial biofertilizers in rice agriculture  

Microsoft Academic Search

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

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

2001-01-01

157

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

158

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

PubMed Central

Background The frequency of cyanobacterial blooms has increased worldwide, and these blooms have been claimed to be a major factor leading to the decline of the most important freshwater herbivores, i.e. representatives of the genus Daphnia. This suppression of Daphnia is partly attributed to the presence of biologically active secondary metabolites in cyanobacteria. Among these metabolites, protease inhibitors are found in almost every natural cyanobacterial bloom and have been shown to specifically inhibit Daphnia's digestive proteases in vitro, but to date no physiological responses of these serine proteases to cyanobacterial protease inhibitors in Daphnia have been reported in situ at the protein and genetic levels. Results Nine digestive proteases were detected in D. magna using activity-stained SDS-PAGE. Subsequent analyses by LC-MS/MS and database search led to the identification of respective protease genes. D. magna responded to dietary protease inhibitors by up-regulation of the expression of these respective proteases at the RNA-level and by the induction of new and less sensitive protease isoforms at the protein level. The up-regulation in response to dietary trypsin- and chymotrypsin-inhibitors ranged from 1.4-fold to 25.6-fold. These physiological responses of Daphnia, i.e. up-regulation of protease expression and the induction of isoforms, took place even after feeding on 20% cyanobacterial food for only 24 h. These physiological responses proved to be independent from microcystin effects. Conclusion Here for the first time it was shown in situ that a D. magna clone responds physiologically to dietary cyanobacterial protease inhibitors by phenotypic plasticity of the targets of these specific inhibitors, i.e. Daphnia gut proteases. These regulatory responses are adaptive for D. magna, as they increase the capacity for protein digestion in the presence of dietary protease inhibitors. The type and extent of these responses in protease expression might determine the degree of growth reduction in D. magna in the presence of cyanobacterial protease inhibitors. The rapid response of Daphnia to cyanobacterial protease inhibitors supports the assumption that dietary cyanobacterial protease inhibitors exert a strong selection pressure on Daphnia proteases themselves. PMID:20441581

2010-01-01

159

Marine and freshwater toxins.  

PubMed

In a very busy and exciting year, 2005 included First Action approval of a much needed official method for paralytic shellfish toxins and multiple international toxin symposia highlighted by groundbreaking research. These are the first-year milestones and activities of the Marine and Freshwater Toxins Task Force and Analytical Community. Inaugurated in 2004 and described in detail in last year's General Referee Report (1) this international toxins group has grown to 150 members from many regions and countries. Perhaps most important they are now making important and global contributions to food safety and to providing alternatives to animal-based assays. Official Method 2005.06 was first approved in late 2004 by the Task Force and subsequently Official First Action in 2005 (2) by the Methods Committee on Natural Toxins and Food Allergens and the Official Methods Board. This nonproprietary method (3) is a precolumn oxidation, liquid chromatographic method that makes good use of fluorescence detection to provide high sensitivity detection of the saxitoxins. It has also proven to be rugged enough for regulatory use and the highest level of validation. As pointed out in the report of method principle investigator and Study Director James Lawrence, approval of 2005.06 now provides the first official alternative to the mouse bioassay after many decades of shellfish monitoring. This past year in April 2005 the group also held their first international conference, "Marine and Freshwater Toxins Analysis: Ist Joint Symposium and AOAC Task Force Meeting," in Baiona, Spain. The 4-day conference consisted of research and stakeholder presentations and symposium-integrated subgroup sessions on ciguatoxins, saxitoxin assays and liquid chromatography (LC) methods for saxitoxins and domoic acids, okadaiates and azaspiracids, and yessotoxins. Many of these subgroups were recently formed in 2005 and are working towards their goals of producing officially validated analytical methods. (Abstracts from the Baiona 2005 meeting cited in this report can be found in the online version of the conference abstract book in the Files and Folders section of the Marine and Freshwater Toxins online community at www.aoac.org.) An active topic for discussion in Baiona and subsequent Task Force activities was the expert consultation for Codex which met in Oslo, Norway in 2004 (previously described and cited in last year's GR report, ref 1). The consultation group's executive summary report (http://www.fao.org/es/ESN/food/risk_biotoxin en.stm) describes suggested changes in action levels as well as methods, method validation, and other issues. September 2005 saw the AOAC Task Force efforts further supported by another symposium, "Marine and Freshwater Toxins: Quality Methods for Food Safety and International Trade," at the AOAC INTERNATIONAL Annual Conference in Orlando, Florida. The multidisciplinary talks at this full day symposium ranged from ciguatoxins to cyanobacterial toxins, and spanned toxicology, biochemistry, molecular biology and analytical chemistry. Again, the symposium preceded Task Force meetings. Toxin subgroups, including a new group on cyanobacterial toxins, met for engaging and productive subgroup discussions. All of these activities were preceded by a Wiley Award symposium for Task Force member Mike Quilliam of NRC Canada. These talks, presented at a half-day symposium on the first day of the Annual Meeting, focused on Quilliam's work with LC tandem mass spectrometry (LC/MS/MS) and certified reference standards and materials, and included related presentations by some of his many research collaborators. To maintain flow and continuity between symposia and between Task Force meetings, the group now uses new electronic discussion forums. Individual subgroup areas, under the Marine and Freshwater Toxins Task Force, comprise this online community. First introduced by AOAC INTERNATIONAL in early 2005, these new resources are being used to distribute information and to supplement the in-person subgroup meetings and electroni

Hungerford, James M

2006-01-01

160

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

161

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

PubMed

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

Torokne, A; Palovics, A; Bankine, M

2001-01-01

162

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

163

Oligopeptides as biomarkers of cyanobacterial subpopulations. Toward an understanding of their biological role.  

PubMed

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

2014-06-01

164

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

165

Molecular identification of the economically important freshwater mussels (Mollusca-Bivalvia-Unionoida) of Thailand: developing species-specific markers from AFLPs.  

PubMed

Shells of certain freshwater mussel (Unionoida) species are highly demanded and serve as raw material for a range of decorative and pharmaceutical products. In Thailand, most animals for this purpose are currently harvested from wild populations, with unionoid culture still being in its infancy. Whilst reliable species identification is a prerequisite for developing a large-scale industry, identification by morphological means is hampered by extensive phenotypic plasticity and poor knowledge of species delimitations. To facilitate alternative molecular identification, we developed species-specific markers for the three Thai unionoids with considerable economic potential (CEP): that is, Chamberlainia hainesiana, Hyriopsis desowitzi and Hyriopsis myersiana. For this purpose, amplified fragment length polymorphism (AFLP) fingerprints using 24 specific primer pairs were generated for eight samples of each CEP species and four samples of the closely related, non-CEP species Contradens contradens. Cloning and sequencing of 13 CEP species-specific AFLP bands revealed fragment collision at three occasions. In total, 16 species-specific primer pairs were designed and tested on 92 Thai specimens spanning seven species and four genera. Thereby, specificity of (1) three primers to C. hainesiana, (2) one primer to H. desowitzi + Hyriopsis bialata, (3) one primer to H. myersiana + H. bialata and (4) four primers to all three Hyriopsis species tested was confirmed. Respective multiplex PCR protocols are provided. The developed primers enable cheap, quick and reliable identification of the Thai CEP species by one to three PCRs and offer a tool for a range of additional applications within mussel culture and ecological and evolutionary research on these important organisms. PMID:24313464

Vannarattanarat, S; Zieritz, A; Kanchanaketu, T; Kovitvadhi, U; Kovitvadhi, S; Hongtrakul, V

2014-04-01

166

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

167

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.

Sciences, Bigelow L.

168

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

169

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

PubMed

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

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

2011-05-01

170

Comparative analysis of cyanobacterial superoxide dismutases to discriminate canonical forms  

PubMed Central

Background Superoxide dismutases (SOD) are ubiquitous metalloenzymes that catalyze the disproportion of superoxide to peroxide and molecular oxygen through alternate oxidation and reduction of their metal ions. In general, SODs are classified into four forms by their catalytic metals namely; FeSOD, MnSOD, Cu/ZnSOD and NiSOD. In addition, a cambialistic form that uses Fe/Mn in its active site also exists. Cyanobacteria, the oxygen evolving photosynthetic prokaryotes, produce reactive oxygen species that can damage cellular components leading to cell death. Thus, the co-evolution of an antioxidant system was necessary for the survival of photosynthetic organisms with SOD as the initial enzyme evolved to alleviate the toxic effect. Cyanobacteria represent the first oxygenic photoautotrophs and their SOD sequences available in the databases lack clear annotation. Hence, the present study focuses on structure and sequence pattern of subsets of cyanobacterial superoxide dismutases. Result The sequence conservation and structural analysis of Fe (Thermosynechococcus elongatus BP1) and MnSOD (Anabaena sp. PCC7120) reveal the sharing of N and C terminal domains. At the C terminal domain, the metal binding motif in cyanoprokaryotes is DVWEHAYY while it is D-X-[WF]-E-H-[STA]-[FY]-[FY] in other pro- and eukaryotes. The cyanobacterial FeSOD differs from MnSOD at least in three ways viz. (i) FeSOD has a metal specific signature F184X3A188Q189.......T280......F/Y303 while, in Mn it is R184X3G188G189......G280......W303, (ii) aspartate ligand forms a hydrogen bond from the active site with the outer sphere residue of W243 in Fe where as it is Q262 in MnSOD; and (iii) two unique lysine residues at positions 201 and 255 with a photosynthetic role, found only in FeSOD. Further, most of the cyanobacterial Mn metalloforms have a specific transmembrane hydrophobic pocket that distinguishes FeSOD from Mn isoform. Cyanobacterial Cu/ZnSOD has a copper domain and two different signatures G-F-H-[ILV]-H-x-[NGT]-[GPDA]-[SQK]-C and G-[GA]-G-G-[AEG]-R-[FIL]-[AG]-C-G, while Ni isoform has an nickel containing SOD domain containing a Ni-hook HCDGPCVYDPA. Conclusion The present analysis unravels the ambiguity among cyanobacterial SOD isoforms. NiSOD is the only SOD found in lower forms; whereas, Fe and Mn occupy the higher orders of cyanobacteria. In conclusion, cyanobacteria harbor either Ni alone or a combination of Fe and Ni or Fe and Mn as their catalytic active metal while Cu/Zn is rare. PMID:18042279

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

2007-01-01

171

Physiological and chemical characterization of cyanobacterial metallothioneins.  

PubMed Central

Techniques have been developed for detection, quantitation, and isolation of bacterial metallothioneins (MTs) from cyanobacterial species. These methods involve differential pulse polarography and reverse-phase high-performance liquid chromatography (HPLC) and have allowed detection of picomole quantities of these high sulfhydryl content proteins. The prokaryotic molecule was found to be induced in the presence of Cd or Zn salts with regulation at the level of transcription. Cu was not found to induce synthesis of the prokaryotic MT. Exposure to the former metals resulted in a growth lag followed by simultaneous induction of MT synthesis and onset of growth. Amino acid analysis and N-terminal sequence analysis indicated that the bacterial MTs from cyanobacteria are unique, having many aromatic and aliphatic residues and no apparent association of hydroxylated or basic amino acids with cysteines. Although the characteristic Cys-X-Cys sequences were present, no apparent amino acid sequence homology with the eukaryotic MTs was found in the first 42 residues. PMID:3086079

Olafson, R W

1986-01-01

172

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

173

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...

174

Prospects for monitoring freshwater ecosystems towards the 2010 targets  

Microsoft Academic Search

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

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

2005-01-01

175

Evaluation of a method for determining concentrations of isoeugenol, an AQUI-S residue, in fillet tissue from freshwater fish species.  

USGS Publications Warehouse

AQUI-S is a fish anesthetic/sedative that is approved for use in a number of countries throughout the world and has the potential for use in the United States. The active ingredient in AQUI-S is isoeugenol. A method for determining isoeugenol concentrations in edible fillet tissue is needed for regulatory purposes, including surveillance and potential use in studies fulfilling human food safety data requirements if U.S. Food and Drug Administration approval is pursued. A method was developed and evaluated for determining isoeugenol concentrations in fillet tissue using relatively common procedures and equipment. The method produced accurate and precise results with fillet tissue from 10 freshwater fish species. The percentage of isoeugenol recovered from samples fortified with isoeugenol at nominal concentrations of 1, 50, and 100 microg/g for all species was always >80 and <97%. Within-day precision for samples fortified at those same concentrations was < or =10%, and day-to-day precision was < or =4.0%. Method precision with fillet tissue containing biologically incurred isoeugenol was < or =8.1%. There were no or minimal chromatographic interferences in control fillet tissue extracts from 9 of the 10 species. The method detection limits for all but one species ranged from 0.004 to 0.014 microg/g, and the quantitation limits ranged from 0.012 to 0.048 microg/g.

Meinertz, J.R.; Schreier, T.M.; Bernardy, J.A.

2008-01-01

176

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

PubMed Central

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

2012-01-01

177

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

178

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.

New Jersey

2006-01-01

179

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...

180

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

181

Freshwater Protected Areas: Strategies for Conservation  

Microsoft Academic Search

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

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

2002-01-01

182

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

183

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

PubMed

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

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

2012-06-01

184

Redescription of Neoechinorhynchus (Neoechinorhynchus) golvani Salgado-Maldonado, 1978 (Acanthocephala: Neoechinorhynchidae) and description of a new species from freshwater cichlids (Teleostei: Cichlidae) in Mexico.  

PubMed

A redescription of Neoechinorhynchus (Neoechinorhynchus) golvani Salgado-Maldonado (An Inst Biol Univ Nal Autón Méx, Ser Zool 49:35-47, 1978) is presented, based on adult specimens collected from the type host Paraneetroplus fenestratus from the type location, the Lago de Catemaco lake, Veracruz state, Mexico, and its presence is recorded in other cichlids. Detailed studies of N. (N.) golvani using light microscopy revealed some taxonomically important, previously unreported features, such as the size and shape of fully developed adult males and females, and the structure of the eggs. Morphological variability in N. (N.) golvani is described. Based on these data, the geographic distribution of this species is documented. Neoechinorhynchus (Neoechinorhynchus) panucensis n. sp. is described from Herichthys labridens (Pellegrin), Amatitlania nigrofasciata (Günther), and Herichthys cyanoguttatus Baird and Girard (all of them Cichlidae), collected in the Río Atlapexco, a tributary to the upper Río Panuco basin, Hidalgo State, Mexico. This new species stand up alone because of its minute proboscis (? 50?×?60, ? 42-55 (48.5)?×?48-63 (57.7)) and anterior hooks (? 27-30 (28.8)?×?3-5 (4), ? 28-32 (30)?×?5 (5)). A key to the species of Neoechinorhynchus recorded from freshwater fishes in Central and South America is included. PMID:23532542

Salgado-Maldonado, Guillermo

2013-05-01

185

Phycobilisomes linker family in cyanobacterial genomes: divergence and evolution  

PubMed Central

Cyanobacteria are the oldest life form making important contributions to global CO2 fixation on the Earth. Phycobilisomes (PBSs) are the major light harvesting systems of most cyanobacteria species. Recent availability of the whole genome database of cyanobacteria provides us a global and further view on the complex structural PBSs. A PBSs linker family is crucial in structure and function of major light-harvesting PBSs complexes. Linker polypeptides are considered to have the same ancestor with other phycobiliproteins (PBPs), and might have been diverged and evolved under particularly selective forces together. In this paper, a total of 192 putative linkers including 167 putative PBSs-associated linker genes and 25 Ferredoxin-NADP oxidoreductase (FNR) genes were detected through whole genome analysis of all 25 cyanobacterial genomes (20 finished and 5 in draft state). We compared the PBSs linker family of cyanobacteria in terms of gene structure, chromosome location, conservation domain, and polymorphic variants, and discussed the features and functions of the PBSs linker family. Most of PBSs-associated linkers in PBSs linker family are assembled into gene clusters with PBPs. A phylogenetic analysis based on protein data demonstrates a possibility of six classes of the linker family in cyanobacteria. Emergence, divergence, and disappearance of PBSs linkers among cyanobacterial species were due to speciation, gene duplication, gene transfer, or gene loss, and acclimation to various environmental selective pressures especially light. PMID:18026567

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

2007-01-01

186

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

187

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

188

Detection and distribution of putative virulence associated genes in Aeromonas species from freshwater and wastewater treatment plant.  

PubMed

The detection of genes responsible for Aeromonas virulence is a vital tool in establishing the potential pathogenicity of the bacteria, as these virulence genes may act alone or in synergy in the establishment of infections. Freshwater and wastewater mixed liquor samples were collected from Kat river and Fort Beaufort wastewater treatment plant in the Eastern Cape Province of South Africa. Polymerase chain reaction was utilized for the amplification of the different genes coding for virulence. All virulence associated genes screened (alt, lip, fla, aer, ast, hlyA) were detected in at least one Aeromonas isolates. In fresh water sample, virulence genes were distributed as follows: lip (67%), aer (43%), alt (33%), fla (62%), ast (10%), and hlyA (86%), while in wastewater samples the occurrence were as follows: lip (92%), aer (21%), alt (54%), fla (83%), ast (29%), and hlyA (88%). The presence of these virulence genes in environmental Aeromonas isolates is of concern to public health as these organisms are potential pathogens in the environment and the virulence determinants could be transferred to aquatic organisms and humans by one mechanism or the other. PMID:23322604

Igbinosa, Isoken H; Okoh, Anthony I

2013-11-01

189

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

PubMed Central

Background Owing to its independence from the main Central European drainage systems, the Italian freshwater fauna is characterized by a high degree of endemicity. Three main ichthyogeographic districts have been proposed in Italy. Yet, the validity of these regions has not been confirmed by phylogenetic and population genetic analyses and a phylogeographic scenario for Italy's primary freshwater fish fauna is still lacking. Here, we investigate the phylogeography of the Italian vairone (Telestes muticellus). Results We sampled 38 populations representing the species' entire distribution range and covering all relevant drainage systems, and genotyped 509 individuals at eight variable microsatellite loci. Applying various population genetic analyses, we identify five distinct groups of populations that are only partly in agreement with the proposed ichthyogeographic districts. Our group I, which is formed by specimens from Veneto and the Po River system draining into the Adriatic Sea, corresponds to the Padano-Venetian ichthyogeographic district (PV), except for two Middle Adriatic drainages, which we identify as a separate group (III). The Tuscano-Latium district (TL) is equivalent to our group V. A more complex picture emerges for the Ligurian drainages: populations from Central Liguria belong to group I, while populations from West (group II) and East Liguria (group IV) form their own groups, albeit with affinities to PV and TL, respectively. Conclusions We propose a phylogeographic scenario for T. muticellus in which an initial T. muticellus stock became isolated from the 'Alpine' clade and survived the various glaciation cycles in several refugia. These were situated in the Upper Adriatic (groups I and II), the Middle Adriatic (group III), (East) Liguria (group IV) and Tuscano-Latium (group V). The population structure in the vairone is, in principal, in agreement with the two main ichthyogeographic districts (PV and TL), except for the two populations in the Middle Adriatic, which we identify as additional major "district". PMID:20423500

2010-01-01

190

Molecular mechanisms of tolerance to cyanobacterial protease inhibitors revealed by clonal differences in Daphnia magna.  

PubMed

Protease inhibitors of primary producers are a major food quality constraint for herbivores. In nutrient-rich freshwater ecosystems, the interaction between primary producers and herbivores is mainly represented by Daphnia and cyanobacteria. Protease inhibitors have been found in many cyanobacterial blooms. These inhibitors have been shown (both in vitro and in situ) to inhibit the most important group of digestive proteases in the daphnid's gut, that is, trypsins and chymotrypsins. In this study, we fed four different Daphnia magna genotypes with the trypsin-inhibitor-containing cyanobacterial strain Microcystis aeruginosa PCC 7806 Mut. Upon exposure to dietary trypsin inhibitors, all D. magna genotypes showed increased gene expression of digestive trypsins and chymotrypsins. Exposure to dietary trypsin inhibitors resulted in increased activity of chymotrypsins and reduced activity of trypsin. Strong intraspecific differences in tolerance of the four D. magna genotypes to the dietary trypsin inhibitors were found. The degree of tolerance depended on the D. magna genotype. The genotypes' tolerance was positively correlated with the residual trypsin activity and the different IC(50) values of the trypsins. On the genetic level, the different trypsin loci varied between the D. magna genotypes. The two tolerant Daphnia genotypes that both originate from the same lake, which frequently produces cyanobacterial blooms, clustered in a neighbour-joining phylogenetic tree based on the three trypsin loci. This suggests that the genetic variability of trypsin loci was an important cause for the observed intraspecific variability in tolerance to cyanobacterial trypsin inhibitors. Based on these findings, it is reasonable to assume that such genetic variability can also be found in natural populations and thus constitutes the basis for local adaptation of natural populations to dietary protease inhibitors. PMID:22943151

Schwarzenberger, Anke; Kuster, Christian J; Von Elert, Eric

2012-10-01

191

CYANOCHIP: An Antibody Microarray for High-Taxonomical-Resolution Cyanobacterial Monitoring.  

PubMed

Cyanobacteria are Gram-negative photosynthetic prokaryotes that are widespread on Earth. Eutrophication and global warming make some aquatic ecosystems behave as bioreactors that trigger rapid and massive cyanobacterial growth with remarkable economic and health consequences. Rapid and efficient early warning systems are required to support decisions by water body authorities. We have produced 17 specific antibodies to the most frequent cyanobacterial strains blooming in freshwater ecosystems, some of which are toxin producers. A sandwich-type antibody microarray immunoassay (CYANOCHIP) was developed for the simultaneous testing of any of the 17 strains, or other closely related strains, in field samples from different habitats (water, rocks, and sediments). We titrated and tested all of the antibodies in succession using a fluorescent sandwich microarray immunoassay. Although most showed high specificity, we applied a deconvolution method based on graph theory to disentangle the few existing cross-reactions. The CYANOCHIP sensitivity ranged from 10(2) to 10(4) cells mL(-1), with most antibodies detecting approximately 10(2) cells mL(-1). We validated the system by testing multiple isolates and crude natural samples from freshwater reservoirs and rocks, both in the laboratory and by in situ testing in the field. The results demonstrated that CYANOCHIP is a valuable tool for the sensitive and reliable detection of cyanobacteria for early warning and research purposes. PMID:25565212

Blanco, Yolanda; Quesada, Antonio; Gallardo-Carreño, Ignacio; Aguirre, Jacobo; Parro, Victor

2015-02-01

192

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

PubMed

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

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

2009-12-01

193

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

194

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

195

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

196

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

Microsoft Academic Search

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

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

2010-01-01

197

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

198

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

Microsoft Academic Search

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

Jeffrey F. Bromaghin

2005-01-01

199

Effects of prolonged flooding on the distribution and biomass of emergent species along a freshwater wetland coenocline  

Microsoft Academic Search

Water levels were raised 1 m for two years in 10 cells of an experimental wetland complex located in the Delta Marsh, Manitoba, Canada. The mean area covered by each of the 5 dominant emergent species in these cells declined significantly during the first year of flooding. There was no significant difference in the total acreage of emergents between flooding

A. G. van der Valk

1994-01-01

200

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

201

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

Microsoft Academic Search

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

Zhourui Wen; Ping Xie; Jun Xu

2010-01-01

202

Persistence of Clostridium botulinum neurotoxin type E in tissues from selected freshwater fish species: implications to public health.  

PubMed

Rainbow trout (Oncorhynchus mykiss), round gobies (Neogobius melanostomas), yellow walleye (Stizostedion vitreum), and yellow perch (Perca flavescens) were given Clostridium botulinum neurotoxin type E (BoNT/E) at four doses (0, 800, 1500, and 4000 mouse lethal doses). BoNT/E was sought in the fish tissues at death or at the conclusion of the experiment (10 days after treatment). Fish were divided into a "fillet" (axial musculature) and a "nonfillet" sample before testing for BoNT/E toxicity with a mouse bioassay. BoNT/E was detected in all species. The percentage of positive BoNT samples ranged across the species and doses from 0 (trout, perch, and walleye) to 17% (round goby) in fillet tissues and from 0 (perch) to 92% (round goby) in nonfillet tissues. The lack of positive fillet samples in three key commercial fish species suggests that the public health implications of eating these fish are minimal. However, the presence of toxin in the nonfillet compartment of a high proportion of fish supports the hypothesis that live intoxicated fish are a vehicle for the transfer of BoNT/E to fish-eating birds, which are then in turn, intoxicated. PMID:16715821

Yule, Adam M; Austin, John W; Barker, Ian K; Cadieux, Brigitte; Moccia, Richard D

2006-05-01

203

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

204

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

205

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

206

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

207

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

208

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

209

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

210

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

211

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

212

Cyanobacterial Toxin Degrading Bacteria: Who Are They?  

PubMed Central

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

Kormas, Konstantinos Ar.; Lymperopoulou, Despoina S.

2013-01-01

213

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

214

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

215

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

216

Temperature-induced activation of freshwater Cyanophage AS-1 prophage  

PubMed Central

Synechococcus sp. IU 625 is one of the freshwater cyanobacteria responsible for harmful algal blooms (HAB). Cyanophages can serve as natural control agents and may be responsible for algal bloom prevention and disappearance. Cyanophage AS-1, which infects Synechococcus sp. IU 625 (Anacystis nidulans) and Synechococcus cedrorum, plays an important role in the environment, significantly altering the numbers of its hosts. Since seasonal (temperature-dependent) lytic induction of cyanobacterial prophage has been proposed to affect seawater algal blooms, we investigated if the AS-1 lytic cycle could be induced by a shift to high temperature. Our hypothesis was confirmed, as more phages were released at 35°C than at 24°C, with maximal induction observed with a shift from 24°C to 35°C. Furthermore, transmission electron microscopy (TEM) images provide direct evidence of lysogenic to lytic conversion with temperature shift. Thus, temperature is an important inducer for AS-1 conversion from lysogenic to lytic cycle and could have applications in terms of modulating cyanobacterial populations in freshwater aquatic environments. The study gives insight into the effect of climate change on the interaction between cyanophage and cyanobacteria in freshwater ecosystems. PMID:20138651

Chu, Tin-Chun; Murray, Sean R; Hsu, Shi-Fang; Vega, Quinn; Lee, Lee H

2009-01-01

217

Rapid determination of arsenic species in freshwater organisms from the arsenic-rich Hayakawa River in Japan using HPLC-ICP-MS.  

PubMed

Speciation analyses of water-soluble arsenicals from freshwater and biological samples collected from the Hayakawa River (Kanagawa, Japan), which contains a high concentration of arsenic, were performed using high performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC-ICP-MS). River water contained only arsenate, which is a pentavalent inorganic arsenical. The water bug Stenopsyche marmorata contained inorganic arsenicals accounting for 77% of the water-soluble arsenicals, followed by oxo-arsenosugar-glycerol, which is a type of dimethylarsinoylriboside (arsenosugar). The freshwater green macroalga Cladophora glomerata contained oxo-arsenosugar-glycerol and oxo-arsenosugar-phosphate as 64% of the water-soluble arsenicals. Production of the same types of arsenosugars was confirmed in the freshwater green microalga Chlamydomonas reinhardtii CC125 experimentally exposed to arsenate. The muscle tissues of all freshwater fish and crustaceans analyzed contained arsenobetaine, oxo-arsenosugar-glycerol, and/or oxo-arsenosugar-phosphate in various concentrations. Seven freshwater fish (Cobitis biwae, Leuciscus hakonensis, Phoxinus lagowski steindachneri, Plecoglossus altivelis, Rhinogobius sp. CB, Rhinogobius sp. CO, Sicyopterus japonicus) and the crustacean Macrobracbium nipponenese contained arsenobetaine in their muscle tissues as the predominant form, contributing up to 80% of the water-soluble arsenicals, while the freshwater fish Anguilla japonica muscle tissues primarily contained dimethylarsinic acid as 77% of the water-soluble arsenicals, followed by arsenobetaine. The freshwater fish Zacco platypus muscle tissues predominantly contained oxo-arsenosugar-phosphate, accounting for 51% of the water-soluble arsenicals, followed by dimethylarsinic acid and arsenobetaine. These biological samples possessed non-extractable arsenical(s) accounting for more than 50% of the total arsenic concentration. PMID:19203781

Miyashita, Shinichi; Shimoya, Masahito; Kamidate, Yoshiaki; Kuroiwa, Takayoshi; Shikino, Osamu; Fujiwara, Shoko; Francesconi, Kevin A; Kaise, Toshikazu

2009-05-01

218

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

219

Freshwater Turtles of Tropical Australia  

E-print Network

Joseph of the Australian National Wildlife Collection for freely providing museum records, and the many for freshwater turtles of tropical Australia and to construct and populate a database to house the information,871 records from the UC Turtle Tissue Database. Most species distributions were very well supported by good

Canberra, University of

220

Freshwater Sculpins: Phylogenetics to Ecology  

Microsoft Academic Search

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

Susan B. Adams; David A. Schmetterling

2007-01-01

221

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

PubMed

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

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

1992-11-01

222

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

223

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

224

Freshwater Mussels (Hyriidae) of Australasia  

Microsoft Academic Search

\\u000a In Australia, New Guinea, Solomon Islands and New Zealand, freshwater mussels are represented by the families Hyriidae and\\u000a Unionidae. The Hyriidae includes 27 species in 8 genera, in the subfamilies Cucumerunioninae, Hyridellinae, Lortiellinae and\\u000a Velesunioninae (a fifth subfamily, the Hyriinae, is endemic to South America). Two other species (one genus) from New Guinea\\u000a are placed tentatively in the Unionidae.

KEITH F. WALKERI; Maria Byrne; Christopher W. Hickey; David S. Roper

225

Periphyton removal by freshwater micrograzers  

Microsoft Academic Search

\\u000a In various experiments, the freshwater snail species Lymnaea peregra (Müll.), Physa fontinalis (L.), Valvata piscinalis (Müll.) and Bithynia tentaculata (L.) significantly removed periphyton from glass slides, while the two tested crustacean species, Asellus aquaticus (L.) and Gammarus pulex (L.), did not. B. tentaculata removed similar amounts of periphyton accumulated in the field as it did of laboratory-cultured periphyton.\\u000a \\u000a \\u000a Removal rates

J. E. Vermaat

1993-01-01

226

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

227

Lake Superior supports novel clusters of cyanobacterial picoplankton.  

PubMed

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

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

2007-06-01

228

Lake Superior Supports Novel Clusters of Cyanobacterial Picoplankton? †  

PubMed Central

Very little is known about the biodiversity of freshwater autotrophic picoplankton (APP) in the Laurentian Great Lakes, a system comprising 20% of the world's lacustrine freshwater. In this study, the genetic diversity of Lake Superior APP was examined by analyzing 16S rRNA gene and cpcBA PCR amplicons from water samples. By neighbor joining, the majority of 16S rRNA gene sequences clustered within the “picocyanobacterial clade” consisting of freshwater and marine Synechococcus and Prochlorococcus. Two new groups of Synechococcus spp., the pelagic Lake Superior clusters I and II, do not group with any of the known freshwater picocyanobacterial clusters and were the most abundant species (50 to 90% of the sequences) in samples collected from offshore Lake Superior stations. Conversely, at station Portage Deep (PD), located in a nearshore urbanized area, only 4% of the sequences belonged to these clusters and the remaining clones reflected the freshwater Synechococcus diversity described previously at sites throughout the world. Supporting the 16S rRNA gene data, the cpcBA library from nearshore station PD revealed a cosmopolitan diversity, whereas the majority of the cpcBA sequences (97.6%) from pelagic station CD1 fell within a unique Lake Superior cluster. Thus far, these picocyanobacteria have not been cultured, although their phylogenetic assignment suggests that they are phycoerythrin (PE) rich, consistent with the observation that PE-rich APP dominate Lake Superior picoplankton. Lastly, flow cytometry revealed that the summertime APP can exceed 105 cells ml?1 and suggests that the APP shifts from a community of PE and phycocyanin-rich picocyanobacteria and picoeukaryotes in winter to a PE-rich community in summer. PMID:17468271

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

2007-01-01

229

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

230

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

231

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

232

Zoogeographic distribution of terrestrial\\/freshwater tardigrades from current literature  

Microsoft Academic Search

The literature on terrestrial and freshwater Tardigrada is relatively limited, being concerned with 617 species world wide. Many of the references are in obscure publications. This paper attempts to bring this information together, tabulating the numbers of tardigrade species recorded from terrestrial and freshwater habitats in various countries and the number of countries from which tardigrades have been recorded. Each

S. J. McInnes

1994-01-01

233

Habitat disturbance and the stability of freshwater gastropod populations  

Microsoft Academic Search

The interaction of population stability and habitat permanence has a major influence on the microdistribution of freshwater snails. For two years (February 1980–January 1982), we monitored the abundance of macrophytes and the abundance and size structure of four species of macrophyte-associated freshwater snails in an English pond. Previous work (Lodge, in press) showed that two species, the pulmonate Lymnaea peregra

D. M. Lodge; P. Kelly

1985-01-01

234

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 ...

235

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

236

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

2014-05-01

237

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

238

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

239

The molecular phylogeny of freshwater Dothideomycetes  

PubMed Central

The freshwater Dothideomycetes species are an ecological rather than taxonomic group and comprise approximately 178 meiosporic and mitosporic species. Due to convergent or parallel morphological adaptations to aquatic habitats, it is difficult to determine phylogenetic relationships among freshwater taxa and among freshwater, marine and terrestrial taxa based solely on morphology. We conducted molecular sequence-based phylogenetic analyses using nuclear ribosomal sequences (SSU and/or LSU) for 84 isolates of described and undescribed freshwater Dothideomycetes and 85 additional taxa representative of the major orders and families of Dothideomycetes. Results indicated that this ecological group is not monophyletic and all the freshwater taxa, except three aeroaquatic Tubeufiaceae, occur in Pleosporomycetidae as opposed to Dothideomycetidae. Four clades comprised of only freshwater taxa were recovered. The largest of these is the Jahnulales clade consisting of 13 species, two of which are the anamorphs Brachiosphaera tropicalis and Xylomyces chlamydosporus. The second most speciose clade is the Lindgomycetaceae clade consisting of nine taxa including the anamorph Taeniolella typhoides. The Lindgomycetaceae clade consists of taxa formerly described in Massarina, Lophiostoma, and Massariosphaeria e.g., Massarina ingoldiana, Lophiostoma breviappendiculatum, and Massariosphaeria typhicola and several newly described and undescribed taxa. The aquatic family Amniculicolaceae, including three species of Amniculicola, Semimassariosphaeria typhicola and the anamorph, Anguillospora longissima, was well supported. A fourth clade of freshwater species consisting of Tingoldiago graminicola, Lentithecium aquaticum, L. arundinaceum and undescribed taxon A-369-2b was not well supported with maximum likelihood bootstrap and Bayesian posterior probability. Eight freshwater taxa occurred along with terrestrial species in the Lophiostoma clades 1 and 2. Two taxa lacking statistical support for their placement with any taxa included in this study are considered singletons within Pleosporomycetidae. These singletons, Ocala scalariformis, and Lepidopterella palustris, are morphologically distinct from other taxa in Pleosporomycetidae. This study suggests that freshwater Dothideomycetes are related to terrestrial taxa and have adapted to freshwater habitats numerous times. In some cases (Jahnulales and Lindgomycetaceae), species radiation appears to have occurred. Additional collections and molecular study are required to further clarify the phylogeny of this interesting ecological group. PMID:20169028

Shearer, C.A.; Raja, H.A.; Miller, A.N.; Nelson, P.; Tanaka, K.; Hirayama, K.; Marvanová, L.; Hyde, K.D.; Zhang, Y.

2009-01-01

240

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...

241

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

242

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

243

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

244

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

Microsoft Academic Search

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

CECILIA M. SANTEGOEDS; STEPHEN C. NOLD; ANDDAVID M. WARD

1996-01-01

245

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

Microsoft Academic Search

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

Pirjo W acklin

246

The course of toxicity in the pregnant mouse after exposure to the cyanobacterial toxin cylindrospermopsin: clinical effects, serum chemistries, hematology, and histopathology.  

PubMed

Cylindrospermopsin (CYN) is a toxin produced by a variety of fresh-water cyanobacterial species worldwide and induces significant adverse effects in both livestock and humans. This study investigated the course of CYN-induced toxicity in pregnant mice exposed daily during either the period of major organogenesis (gestation days [GD] 8-12) or fetal growth (GD13-17). Endpoints include clinical signs of toxicity, serum analyses to evaluate hepatic and renal function, histopathology of liver and kidney, and hematology. Study animals were administered 50 ?g/kg CYN once daily by ip route and euthanized 24 h after 1, 2, 3, 4, or 5 consecutive doses, or 6 or 13 d after the dosing period. The course of the CYN-induced effects was determined at all euthanasia times for the endpoints just outlined. Results indicated that CYN is a toxin, producing lethality in dams during the early part of gestation, significant weight loss, and bleeding in the gastrointestinal tract, tail tip, and peri-orbital tissues. Effects also included alterations in serum markers for liver function, histopathological changes in liver and kidney tissues, electrolyte abnormalities, leukocytosis, and posttreatment thrombocytopenia and reticulocytosis. The onset of symptoms was rapid, producing reductions in weight gain in GD8-12 animals, bleeding in the vaginal area in GD13-17 animals, and significant increases in sorbitol dehydrogenase (SDH) in both groups after a single dose. Although the GD8-12 dams displayed a 50% lethality, in GD13-17 animals only a single death occurred. Alterations seen in hepatic and renal function or histopathology do not appear to be of sufficient severity to produce death. Evidence indicates that bleeding may play a critical role in the onset of symptoms and eventually, in the observed lethality. PMID:25072824

Chernoff, N; Rogers, E H; Zehr, R D; Gage, M I; Travlos, G S; Malarkey, D E; Brix, A; Schmid, J E; Hill, D

2014-01-01

247

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

PubMed Central

A key process in freshwater plankton food webs is the regulation of the efficiency of energy and material transfer. Cyanobacterial carbon (C) in particular is transferred very inefficiently to herbivorous zooplankton, which leads to a decoupling of primary and secondary production and the accumulation of cyanobacterial biomass, which is associated with reduced recreational quality of water bodies and hazards to human health. A recent correlative field study suggested that the low transfer efficiency of cyanobacterial C is the result of the absence of long-chain polyunsaturated fatty acids (PUFA) in the diet of the zooplankton. By supplementation of single-lipid compounds in controlled growth experiments, we show here that the low C transfer efficiency of coccal and filamentous cyanobacteria to the keystone herbivore Daphnia is caused by the low sterol content in cyanobacteria, which constrains cholesterol synthesis and thereby growth and reproduction of the herbivore. Estimations of sterol requirement in Daphnia suggest that, when cyanobacteria comprise more than 80% of the grazed phytoplankton, growth of the herbivore may be limited by sterols and Daphnia may subsequently fail to control phytoplankton biomass. Dietary sterols therefore may play a key role in freshwater food webs and in the control of water quality in lakes dominated by cyanobacteria. PMID:12816661

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

2003-01-01

248

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...

249

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 “...

250

16S rRNA sequences of uncultivated hot spring cyanobacterial mat inhabitants retrieved as randomly primed cDNA  

SciTech Connect

Cloning and analysis of cDNAs synthesized from rRNAs is one approach to assess the species composition of natural microbial communities. In some earlier attempts to synthesize cDNA from 16S rRNA (16S rcDNA) from the Octopus Spring cyanobacterial mat, a dominance of short 16S rcDNAs was observed, which appear to have originated only from certain organisms. Priming of cDNA synthesis from small ribosomal subunit RNA with random deoxyhexanucleotides can retrieve longer sequences, more suitable for phylogenetic analysis. Here we report the retrieval of 16S rRNA sequences form three formerly uncultured community members. One sequence type, which was retrieved three times from a total of five sequences analyzed, can be placed in the cyanobacterial phylum. A second sequence type is related to 16S rRNAs from green nonsulfur bacteria. The third sequence type may represent a novel phylogenetic type.

Weller, R.; Ward, D.M. (Montana State Univ., Bozeman (United States)); Weller, J.W. (Univ. of Montana, Missoula (United States))

1991-04-01

251

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

E-print Network

The 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 proteins, which could also be involved in photosynthesis. Only a few components of cyanobacterial

Steinhoff, Heinz-Jürgen

252

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

253

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

254

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.

255

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

256

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

257

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

258

A cyanobacterial phytochrome two-component light sensory system.  

PubMed

The biliprotein phytochrome regulates plant growth and developmental responses to the ambient light environment through an unknown mechanism. Biochemical analyses demonstrate that phytochrome is an ancient molecule that evolved from a more compact light sensor in cyanobacteria. The cyanobacterial phytochrome Cph1 is a light-regulated histidine kinase that mediates red, far-red reversible phosphorylation of a small response regulator, Rcp1 (response regulator for cyanobacterial phytochrome), encoded by the adjacent gene, thus implicating protein phosphorylation-dephosphorylation in the initial step of light signal transduction by phytochrome. PMID:9278513

Yeh, K C; Wu, S H; Murphy, J T; Lagarias, J C

1997-09-01

259

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

260

Schagerl M.: Problems in species delineation a study of the genus Spirogyra Coffee break  

E-print Network

break KarnkowskaIshikawa A.: Phylogeny and taxonomy of green euglenoids Veselá J., Urbánková P of planktonic and soil representatives of the cyanobacterial genus Anabaena Skaloud P., Skaloudová M.: Hidden and freshwater habitats Taxonomy and molecular phylogeny Biodiversity, Applied Phycology Coffee break Viltová N

261

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; Fazio, Victor W. (1962-)

262

Global warming and cyanobacterial harmful algal blooms.  

PubMed

The Earth and the oceans have warmed significantly over the past four decades, providing evidence that the Earth is undergoing long-term climate change. Increasing temperatures and changing rainfall patterns have been documented. Cyanobacteria have a long evolutionary history, with their first occurrence dating back at least 2.7 billion years ago. Cyanobacteria often dominated the oceans after past mass extinction events. They evolved under anoxic conditions and are well adapted to environmental stress including exposure to UV, high solar radiation and temperatures, scarce and abundant nutrients. These environmental conditions favor the dominance of cyanobacteria in many aquatic habitats, from freshwater to marine ecosystems. A few studies have examined the ecological consequences of global warming on cyanobacteria and other phytoplankton over the past decades in freshwater, estuarine, and marine environments, with varying results. The responses of cyanobacteria to changing environmental patterns associated with global climate change are important subjects for future research. Results of this research will have ecological and biogeochemical significance as well as management implications. PMID:18461772

Paul, Valerie J

2008-01-01

263

Toxicity of vanadium to different freshwater organisms  

SciTech Connect

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

Beusen, J.M.; Neven, B.

1987-08-01

264

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...

265

NUTRIENT CYCLING BY ANIMALS IN FRESHWATER ECOSYSTEMS  

Microsoft Academic Search

? Abstract Animals are important in nutrient cycling in freshwater ecosystems. Via excretory processes, animals can supply nutrients (nitrogen and phosphorus) at rates comparable to major nutrient sources, and nutrient cycling by animals can sup- port a substantial proportion of the nutrient demands of primary producers. In addition, animals may exert strong impacts on the species composition of primary producers

Michael J. Vanni

266

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

Microsoft Academic Search

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

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

2005-01-01

267

Molecular Mechanism of Photoactivation and Structural Location of the Cyanobacterial Orange Carotenoid Protein  

PubMed Central

The Orange Carotenoid Protein (OCP) plays a similar photoprotective role in cyanobacterial photosynthesis to that of non-photochemical quenching in higher plants. Under high-light conditions, OCP binds to the phycobilisome (PBS) and reduces energy transfer to the photosystems. The protective cycle starts from a light-induced activation of OCP. Detailed information on the molecular mechanism of this process as well as the subsequent recruitment of active OCP to the phycobilisome is not known. We report here our investigation on OCP photoactivation from the cyanobacterium Synechocystis sp. PCC 6803 by using a combination of native mass spectrometry (MS) and protein cross-linking. We demonstrate that Native MS is able to capture OCP with its intact pigment and further reveal that OCP undergoes a dimer-tomonomer transition upon light illumination. The reversion of activated form of OCP to inactive, dark form was also observed by using native MS. Furthermore, in vitro reconstitution of OCP and PBS allowed to perform protein chemical cross-linking experiments. LC-MS/MS analysis identified cross-linking species between OCP and the PBS core components. Our result indicates that the N-terminal domain of 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 helps to understand the activation mechanism of OCP and the structural binding site of OCP during the cyanobacterial non-photochemical quenching process. PMID:24359496

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

2014-01-01

268

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

269

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...

270

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

E-print Network

natural water systems are iodide, iodate, and organic iodine. Using this new method, iodide was determined directly by combining anion exchange chromatography and spectrophotometry. Iodate and the total of organic iodine species are determined as iodide...

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

271

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

Microsoft Academic Search

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

Ronald A. Englund

2002-01-01

272

Conservation genetics of the endangered eastern freshwater cod, Maccullochella ikei  

Microsoft Academic Search

Fragmentation over evolutionary time scales following vicariant and dispersal events has long been recognised as a dominant process in biological diversification and speciation; while anthropogenic habitat fragmentation in recent times is considered a threat to the long-term persistence of species and ecosystems.\\u000aThe eastern freshwater cod Maccullochella ikei is Australia’s largest endangered freshwater fish species. Abundant in the Clarence and

Catherine Jane Nock

2010-01-01

273

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

274

Molecular evolution of sensory domains in cyanobacterial chemoreceptors  

Microsoft Academic Search

Components of the chemotaxis system encoded in multiple heomologous operons were identified in five cyanobacterial genomes. Analysis of phylogenetic profiles, genomic context, domain architectures and sequence identity reveal that sensory modules of chemoreceptors that detect environmental cues are the subject of frequent domain birth and death events and have accelerated rates of sequence evolution. This fact could explain a remarkable

Kristin Wuichet; Igor B. Zhulin

2003-01-01

275

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...

276

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

PubMed

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

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

2010-01-01

277

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

PubMed Central

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

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

2009-01-01

278

Transboundary Freshwater Dispute Database  

NSDL National Science Digital Library

This collection of databases is intended to aid in the assessment of the process of water conflict prevention and resolution. The searchable collections include data such as case studies, freshwater treaties from 1820 to 2001, events concerning historical water relations from 1948 to 1999, a register of international river basins, and information on interstate water compacts in the United States. There is also spatial data on transboundary freshwater indicator variables, international river basins, and a map and image gallery. Other materials include links to the organization's publications and research projects, and a set of links to other databases and publications on freshwater conflict issues.

279

UV Radiation and Arctic Freshwater Zooplankton  

Microsoft Academic Search

\\u000a Arctic freshwaters possess simple zooplankton communities.The high Arctic lakes and ponds are commonly inhabited by only a\\u000a few species of rotifers, cladocerans and copepods. Dominant inhabitants of high Arctic zooplankton communities are first and\\u000a foremost members of the circumpolar cladoceran species Daphnia pulex complex (Colbourne et al. 1998; Weider et al. 1999). Members of this complex are recorded in all

D. O. Hessen

280

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

281

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

282

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

283

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...

284

Transatlantic Freshwater Aqueduct  

Microsoft Academic Search

This paper offers a technical and geopolitical reappraisal of a macro-engineering proposal to plumb Earth’s freshwater, siphoning\\u000a some of it from a region of surplus (Amazon River Basin) to a region of shortage (arid northern Africa) via his positively buoyant (subsurface floating) seabed-anchored Transatlantic Freshwater Aqueduct. Two different routes for\\u000a the pipeline, of length 4,317 and 3,745 km, respectively, have been

Viorel Badescu; Dragos Isvoranu; Richard B. Cathcart

2010-01-01

285

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

286

The Freshwater Shrimps Of Curaçao, West Indies (decapoda, Caridea)  

Microsoft Academic Search

On the basis of a é eld survey and review of existing records I here report on the occurrence of ten freshwater shrimp species in Curaç ao. Four species constitute new and\\/or previously unpublished records for the island. Existing records for the neighbouring islands of Bonaire and Aruba are reviewed. The most common species are Macrobrachium carcinus , M. crenulatum,

Adolphe O. Debrot

2003-01-01

287

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

288

Freshwater biodiversity and aquatic insect diversification.  

PubMed

Inland waters cover less than 1% of Earth's surface but harbor more than 6% of all insect species: Nearly 100,000 species from 12 orders spend one or more life stages in freshwater. Little is known about how this remarkable diversity arose, although allopatric speciation and ecological adaptation are thought to be primary mechanisms. Freshwater habitats are highly susceptible to environmental change and exhibit marked ecological gradients. Standing waters appear to harbor more dispersive species than running waters, but there is little understanding of how this fundamental ecological difference has affected diversification. In contrast to the lack of evolutionary studies, the ecology and habitat preferences of aquatic insects have been intensively studied, in part because of their widespread use as bioindicators. The combination of phylogenetics with the extensive ecological data provides a promising avenue for future research, making aquatic insects highly suitable models for the study of ecological diversification. PMID:24160433

Dijkstra, Klaas-Douwe B; Monaghan, Michael T; Pauls, Steffen U

2014-01-01

289

Regulatory and Structural Properties of the Cyanobacterial ADPglucose Pyrophosphorylases.  

PubMed

ADPglucose pyrophosphorylase (EC 2.7.7.27) has been purified from two cyanobacteria: the filamentous, heterocystic, Anabaena PCC 7120 and the unicellular Synechocystis PCC 6803. The purification procedure gave highly purified enzymes from both cynobacteria with specific activities of 134 (Synechocystis) and 111 (Anabaena) units per milligram protein. The purified enzymes migrated as a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with molecular mass corresponding to 53 (Synechocystis) and 50 (Anabaena) kilodaltons. Tetrameric structures were determined for the native enzymes by analysis of gel filtrations. Kinetic and regulatory properties were characterized for the cyanobacterial ADPglucose pyrophosphorylases. Inorganic phosphate and 3-phosphoglycerate were the most potent inhibitor and activator, respectively. The Synechocystis enzyme was activated 126-fold by 3-phosphoglycerate, with saturation curves exhibiting sigmoidicity (A(0.5) = 0.81 millimolar; n(H) = 2.0). Activation by 3-phosphoglycerate of the enzyme from Anabaena demonstrated hyperbolic kinetics (A(0.5) = 0.12 millimolar; n(H) = 1.0), having a maximal stimulation of 17-fold. I(0.5) values of 95 and 44 micromolar were calculated for the inhibition by inorganic phosphate of the Synechocystis and Anabaena enzyme, respectively. Pyridoxal-phosphate behaved as an activator of the cyanobacterial enzyme. It activated the enzyme from Synechocystis nearly 10-fold with high apparent affinity (A(0.5) = 10 micromolar; n(H) = 1.8). Phenylglyoxal modified the cyanobacterial enzyme by inactivating the activity in the presence of 3-phosphoglycerate. Antibody neutralization experiments showed that anti-spinach leaf (but not anti-Escherichia coli) ADPglucose pyrophosphorylase serum inactivated the enzyme from cyanobacteria. When the cyanobacterial enzymes were resolved on sodium dodecyl sulfate- and two-dimensional polyacrylamide gel electrophoresis and probed with Western blots, only one protein band was recognized by the anti-spinach leaf serum. The same polypeptide strongly reacted with antiserum prepared against the smaller spinach leaf 51 kilodalton subunit, whereas the anti-54 kilodalton antibody raised against the spinach subunit reacted weakly to the cyanobacterial subunit. Regulatory and immunological properties of the cyanobacterial enzyme are more related to the higher plant than the bacterial enzyme. Despite this, results suggest that the ADPglucose pyrophosphorylase from cyanobacteria is homotetrameric in structure, in contrast to the reported heterotetrameric structures of the higher plant ADPglucose pyrophosphorylase. PMID:16668507

Iglesias, A A; Kakefuda, G; Preiss, J

1991-11-01

290

Regulatory and Structural Properties of the Cyanobacterial ADPglucose Pyrophosphorylases 1  

PubMed Central

ADPglucose pyrophosphorylase (EC 2.7.7.27) has been purified from two cyanobacteria: the filamentous, heterocystic, Anabaena PCC 7120 and the unicellular Synechocystis PCC 6803. The purification procedure gave highly purified enzymes from both cynobacteria with specific activities of 134 (Synechocystis) and 111 (Anabaena) units per milligram protein. The purified enzymes migrated as a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with molecular mass corresponding to 53 (Synechocystis) and 50 (Anabaena) kilodaltons. Tetrameric structures were determined for the native enzymes by analysis of gel filtrations. Kinetic and regulatory properties were characterized for the cyanobacterial ADPglucose pyrophosphorylases. Inorganic phosphate and 3-phosphoglycerate were the most potent inhibitor and activator, respectively. The Synechocystis enzyme was activated 126-fold by 3-phosphoglycerate, with saturation curves exhibiting sigmoidicity (A0.5 = 0.81 millimolar; nH = 2.0). Activation by 3-phosphoglycerate of the enzyme from Anabaena demonstrated hyperbolic kinetics (A0.5 = 0.12 millimolar; nH = 1.0), having a maximal stimulation of 17-fold. I0.5 values of 95 and 44 micromolar were calculated for the inhibition by inorganic phosphate of the Synechocystis and Anabaena enzyme, respectively. Pyridoxal-phosphate behaved as an activator of the cyanobacterial enzyme. It activated the enzyme from Synechocystis nearly 10-fold with high apparent affinity (A0.5 = 10 micromolar; nH = 1.8). Phenylglyoxal modified the cyanobacterial enzyme by inactivating the activity in the presence of 3-phosphoglycerate. Antibody neutralization experiments showed that anti-spinach leaf (but not anti-Escherichia coli) ADPglucose pyrophosphorylase serum inactivated the enzyme from cyanobacteria. When the cyanobacterial enzymes were resolved on sodium dodecyl sulfate- and two-dimensional polyacrylamide gel electrophoresis and probed with Western blots, only one protein band was recognized by the anti-spinach leaf serum. The same polypeptide strongly reacted with antiserum prepared against the smaller spinach leaf 51 kilodalton subunit, whereas the anti-54 kilodalton antibody raised against the spinach subunit reacted weakly to the cyanobacterial subunit. Regulatory and immunological properties of the cyanobacterial enzyme are more related to the higher plant than the bacterial enzyme. Despite this, results suggest that the ADPglucose pyrophosphorylase from cyanobacteria is homotetrameric in structure, in contrast to the reported heterotetrameric structures of the higher plant ADPglucose pyrophosphorylase. ImagesFigure 1Figure 6Figure 7 PMID:16668507

Iglesias, Alberto A.; Kakefuda, Genichi; Preiss, Jack

1991-01-01

291

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

292

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

293

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

Microsoft Academic Search

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

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

2010-01-01

294

GC constituents and relative codon expressed amino acid composition in cyanobacterial phycobiliproteins.  

PubMed

The genomic as well as structural relationship of phycobiliproteins (PBPs) in different cyanobacterial species are determined by nucleotides as well as amino acid composition. The genomic GC constituents influence the amino acid variability and codon usage of particular subunit of PBPs. We have analyzed 11 cyanobacterial species to explore the variation of amino acids and causal relationship between GC constituents and codon usage. The study at the first, second and third levels of GC content showed relatively more amino acid variability on the levels of G3+C3 position in comparison to the first and second positions. The amino acid encoded GC rich level including G rich and C rich or both correlate the codon variability and amino acid availability. The fluctuation in amino acids such as Arg, Ala, His, Asp, Gly, Leu and Glu in ? and ? subunits was observed at G1C1 position; however, fluctuation in other amino acids such as Ser, Thr, Cys and Trp was observed at G2C2 position. The coding selection pressure of amino acids such as Ala, Thr, Tyr, Asp, Gly, Ile, Leu, Asn, and Ser in ? and ? subunits of PBPs was more elaborated at G3C3 position. In this study, we observed that each subunit of PBPs is codon specific for particular amino acid. These results suggest that genomic constraint linked with GC constituents selects the codon for particular amino acids and furthermore, the codon level study may be a novel approach to explore many problems associated with genomics and proteomics of cyanobacteria. PMID:24933001

Kannaujiya, Vinod K; Rastogi, Rajesh P; Sinha, Rajeshwar P

2014-08-10

295

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

296

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

297

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...

298

Evolution of active host-attraction strategies in the freshwater mussel tribe Lampsilini (Bivalvia: Unionidae)  

Microsoft Academic Search

Most freshwater mussels (Bivalvia: Unionoida) require a host, usually a fish, to complete their life cycle. Most species of mussels show adaptations that increase the chances of glochidia larvae contacting a host. We investigated the evolutionary relationships of the freshwater mussel tribe Lampsilini including 49 of the approximately 100 extant species including 21 of the 24 recognized genera. Mitochondrial DNA

David T. Zanatta; Robert W. Murphy

2006-01-01

299

A Review of the Freshwater Fishes of Curacao, with Comments on those of Aruba and Bonaire  

Microsoft Academic Search

Based on a field survey and review of published records, I report the occurrence of 13 species of fishes in fresh waters of Curacao. Seven species are new or previously unpublished freshwater records for the island. New records are also provided for the adjacent islands of Aruba and Bonaire. Although the native freshwater fish fauna is dominated by predatory gobiid

ADOLPHE O. DEBROT

2003-01-01

300

Cyanobacterial diversity and activity in modern conical microbialites.  

PubMed

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

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

2012-09-01

301

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

302

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

303

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

304

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

305

Biological effect of the Planktothrix sp. FP1 cyanobacterial extract  

Microsoft Academic Search

Cyanobacteria are common and potentially harmful inhabitants of freshwater and marine environments worldwide. Some waterbloom-forming cyanobacteria are toxic and they may cause animal death and adversely affect human health. A filamentous freshwater cyanobacterium, Planktothrix sp. FP1, was found to be responsible for a toxic algal bloom in Lake Varese (Italy) during August of 1997. In the present study, the biological

M. Prati; M. Molteni; F. Pomati; C. Rossetti; G. Bernardini

2002-01-01

306

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

307

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.

308

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

PubMed Central

Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these cyanobacteria. Results Deciphering the 5,172,804 bp sequence of Microcystis aeruginosa PCC 7806 has revealed the high plasticity of its genome: 11.7% DNA repeats containing more than 1,000 bases, 6.8% putative transposases and 21 putative restriction enzymes. Compared to the genomes of other cyanobacterial lineages, strain PCC 7806 contains a large number of atypical genes that may have been acquired by lateral transfers. Metabolic pathways, such as fermentation and a methionine salvage pathway, have been identified, as have genes for programmed cell death that may be related to the rapid disappearance of Microcystis blooms in nature. Analysis of the PCC 7806 genome also reveals striking novel biosynthetic features that might help to elucidate the ecological impact of secondary metabolites and lead to the discovery of novel metabolites for new biotechnological applications. M. aeruginosa and other large cyanobacterial genomes exhibit a rapid loss of synteny in contrast to other microbial genomes. Conclusion Microcystis aeruginosa PCC 7806 appears to have adopted an evolutionary strategy relying on unusual genome plasticity to adapt to eutrophic freshwater ecosystems, a property shared by another strain of M. aeruginosa (NIES-843). Comparisons of the genomes of PCC 7806 and other cyanobacterial strains indicate that a similar strategy may have also been used by the marine strain Crocosphaera watsonii WH8501 to adapt to other ecological niches, such as oligotrophic open oceans. PMID:18534010

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

2008-01-01

309

A freshwater bacterial strain, Shewanella sp. Lzh-2, isolated from Lake Taihu and its two algicidal active substances, hexahydropyrrolo[1,2-a]pyrazine-1,4-dione and 2, 3-indolinedione.  

PubMed

Cyanobacterial blooms have become a serious problem in Lake Taihu during the last 20 years, and Microcystis aeruginosa and Synechococcus sp. are the two dominant species in cyanobacterial blooms of Lake Taihu. A freshwater bacterial strain, Shewanella sp. Lzh-2, with strong algicidal properties against harmful cyanobacteria was isolated from Lake Taihu. Two substances with algicidal activity secreted extracellularly by Shewanella sp. Lzh-2, S-2A and S-2B, were purified from the bacterial culture of strain Lzh-2 using ethyl acetate extraction, column chromatography, and high performance liquid chromatography (HPLC) in turn. The substances S-2A and S-2B were identified as hexahydropyrrolo[1,2-a]pyrazine-1,4-dione and 2, 3-indolinedione (isatin), respectively, based on liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GC-MS), and hydrogen-nuclear magnetic resonance (H-NMR) analyses, making this the first report of their algicidal activity toward cyanobacteria. S-2A (hexahydropyrrolo[1,2-a]pyrazine-1,4-dione) had no algicidal effects against Synechococcus sp. BN60, but had a high level of algicidal activity against M. aeruginosa 9110. The LD50 value of S-2A against M. aeruginosa 9110 was 5.7 ?g/ml. S-2B (2, 3-indolinedione) showed a potent algicidal effect against both M. aeruginosa 9110 and Synechococcus sp. BN60, and the LD50 value of S-2B against M. aeruginosa 9110 and Synechococcus sp. BN60 was 12.5 and 34.2 ?g/ml, respectively. Obvious morphological changes in M. aeruginosa 9110 and Synechococcus sp. BN60 were observed after they were exposed to S-2A (or S-2B) for 24 h. Approximately, the algicidal activity, the concentration of S-2A and S-2B, and the cell density of Lzh-2 were positively related to each other during the cocultivation process. Overall, these findings increase our knowledge about algicidal substances secreted by algicidal bacteria and indicate that strain Lzh-2 and its two algicidal substances have the potential for use as a bio-agent in controlling cyanobacterial blooms in Lake Taihu. PMID:24566920

Li, Zhenghua; Lin, Shengqin; Liu, Xianglong; Tan, Jing; Pan, Jianliang; Yang, Hong

2014-05-01

310

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

PubMed

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

Sedmak, B; Kosi, G

1997-01-01

311

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

312

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

313

NUTRIENT CYCLING BY ANIMALS IN FRESHWATER ECOSYSTEMS  

Microsoft Academic Search

? Abstract Animals are important,in nutrient cycling in freshwater ecosystems. Via excretory processes, animals can supply nutrients (nitrogen and phosphorus) at rates comparable to major nutrient sources, and nutrient cycling by animals can sup- port a substantial proportion of the nutrient demands of primary producers. In addition, animals may,exert strong impacts on the species composition,of primary producers via effects on

Michael J. Vanni

2002-01-01

314

An in vivo system involving co-expression of cyanobacterial flavodoxin and ferredoxin-NADP(+) reductase confers increased tolerance to oxidative stress in plants.  

PubMed

Oxidative stress in plants causes ferredoxin down-regulation and NADP(+) shortage, over-reduction of the photosynthetic electron transport chain, electron leakage to oxygen and generation of reactive oxygen species (ROS). Expression of cyanobacterial flavodoxin in tobacco chloroplasts compensates for ferredoxin decline and restores electron delivery to productive routes, resulting in enhanced stress tolerance. We have designed an in vivo system to optimize flavodoxin reduction and NADP(+) regeneration under stress using a version of cyanobacterial ferredoxin-NADP(+) reductase without the thylakoid-binding domain. Co-expression of the two soluble flavoproteins in the chloroplast stroma resulted in lines displaying maximal tolerance to redox-cycling oxidants, lower damage and decreased ROS accumulation. The results underscore the importance of chloroplast redox homeostasis in plants exposed to adverse conditions, and provide a tool to improve crop tolerance toward environmental hardships. PMID:23650570

Giró, Mariana; Ceccoli, Romina D; Poli, Hugo O; Carrillo, Néstor; Lodeyro, Anabella F

2011-12-01

315

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

316

nonindigenous freshwater bryozoans  

Microsoft Academic Search

Aim The transport of organisms in ships' ballast tanks is a dominant vector for aquatic invasions worldwide. Until recently, efforts to manage this vector have overlooked the potential transport of invertebrate resting stages in the residual waters and sediments within emptied ballast tanks, i.e. NOBOB ('No Ballast On Board') tanks. The resting stages (statoblasts) of freshwater bryozoans are often buoyant

R. Kipp; S. A. Bailey; H. J. MacIsaac; A. Ricciardi

2010-01-01

317

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

2015-01-01

318

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

SciTech Connect

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

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

2007-05-01

319

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

Microsoft Academic Search

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

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

2005-01-01

320

Development of a new biotic index to assess freshwater pollution  

Microsoft Academic Search

We developed a new biotic index of species pollution value (SPV) and community pollution value (CPV) based on the correlation of protozoan communities with chemical water quality to assess freshwater pollution. Five hundred and twenty-three species of protozoa SPV were established based on the data of River Hangjiang and Lake Donghu. The present research was conducted in order to further

Jian-Guo Jiang

2006-01-01

321

Macrophyte colonization in a freshwater tidal wetland (Lyme, CT, USA)  

Microsoft Academic Search

Seed bank sampling and creation of plots cleared of standing vegetation showed that aboveground vegetative propagules were more important than seeds in colonization of a freshwater tidal wetland but that the relative importance of sexual reproduction varied among species. Nine submerged species established in colonization plots. Of these colonization events, 60% were achieved by plant fragments, either in the sediment

Robert S. Capers

2003-01-01

322

Comparison of the respiratory metabolism of juvenile Litopenaeus vannamei cultured in seawater and freshwater  

NASA Astrophysics Data System (ADS)

Litopenaeus vannamei, a euryhaline species, can be cultured at a wide range of salinities. The emergence of freshwater pond-culture of L. vannamei is an important prelude to the continued development of shrimp culture in China. In this study, we compared the respiratory metabolism of juvenile L. vannamei cultured in freshwater and saltwater by measuring their oxygen consumption rate (OCR), ammonium-type nitrogen excretion rate (AER) and pyruvate kinase (PK) and lactate dehydrogenase (LDH) activities at different molting stages in order to physiecologically characterize juvenile L. vannamei under freshwater conditions. The results showed that OCR was significantly higher in saltwater than in freshwater at all stages of molting cycle. However, variation of OCR among molting stages in saltwater was similar with that in freshwater, and the highest OCR was observed at post-molting stage. At all stages of molting cycle, AER was significantly higher in freshwater than in saltwater, and the highest was observed at post-molting stage. The activity of PK was significantly higher in saltwater than in freshwater. Conversely, the activity of LDH was higher in freshwater than in saltwater in general. Significant variation of PK and LDH activities in molting cycle was observed in saltwater and freshwater. The results indicated that aerobic metabolism of juvenile L. vannamei was more active in saltwater than in freshwater; while its protein metabolism was more active in freshwater than in saltwater.

Ding, Sen; Wang, Fang; Dong, Shuanglin; Li, Ying

2013-11-01

323

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

324

Persistence of environmental DNA in freshwater ecosystems.  

PubMed

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

325

Late Archean mineralised cyanobacterial mats and their modern analogs  

NASA Astrophysics Data System (ADS)

Abstract Reported are findings of Neoarchean benthic colonial coccoid cyanobacteria preserved as abundant remnants of mineralized capsules and sheaths visible in SEM images as characteristic patterns after etching highly polished carbonate rock platelets. The samples described herein were collected from the Nauga Formation at Prieska (Kaapvaal craton, South Africa). The stratigraphic position of the sampling horizon (Fig. 1) is bracketed by single zircon ages from intercalated tuffs, of 2588±6 Ma and 2549±7Ma [1]. The cyanobacteria-bearing samples are located within sedimentary sequence which begins with Peritidal Member displaying increasingly transgressive character, passing upward into the Chert Member and followed by the Proto-BIF Member and by the Naute Shale Member of the Nauga Formation successively. All three latter members were deposited below the fair weather wave base. As in our previous report [2], the samples are taken from lenses of massive micritic flat pebble conglomerate occurring in otherwise finely laminated siliceous shales intercalating with thin bedded platy limestone. This part of the Nauga Formation is about 30 m thick. The calcareous, cyanobacteria-bearing flat pebble conglomerate and thin intercalations of fine-grained detrital limestones embedded in the clayey sapropel-rich deposits are interpreted as carbonate sediments winnowed during stormy weather from the nearby located peritidal carbonate platform. The mass occurrence and exceptional preservation of mineralised cyanobacterial remains in the micritic carbonate (Mg-calcite) of the redeposited flat pebbles can be explained by their sudden burial in deeper, probably anoxic clay- and sapropel-rich sediments. When examined with standard petrographic optical microscopic technique, the micritic carbonates show rather obscure structure (Fig. 2a), whereas under the SEM, polished and slightly etched platelets of the same samples reveal surprisingly well preserved patterns (Fig. 2b,c) reminiscent of common sheaths (glycocalix), typical for coccoidal colonial (pseudoparenchymatous) entophysalidacean or pleurocapsalean cyanobacteria (Fig. 2d-f). The remains of the coccoid sheaths and capsules are visible as a system of rimmed subglobular or irregularly polygonal pits separated from adjacent pits by 2-3 ?m thick walls. Microprobe analyses show that the interiors of the pits are composed of almost pure calcium carbonate whereas the rims and walls of calcium carbonate with high admixture of silicates (mostly Al-Fe clay-like silicates) and dolomite. High magnification images of rims and walls confirm the microprobe data indicating authigenic character of the minerals forming both the carbonate infilling the pits interiors (CaCO3) and their rims and walls (CaCO3 + Al-Fe silicates + dolomite). EPSC Abstracts, Vol. 3, EPSC2008-A-00493, 2008 European Planetary Science Congress, Author(s) 2008 It seems that carbonates were the first mineral phase filling the spaces remained after the plasmolysis of the cyanobacterial cell contents, whereas the formation of silicates within the exopolysaccharides forming the bulk of the sheaths and capsules was a later diagenetic process. Microprobe analyses of mineralised modern coccoid cyanobacterial mats forming tower-like structures in the highly alkaline Lake Van, Turkey [3,4] display a set of elements indicative for the presence of authigenic carbonate and silicate minerals which are almost identical with that occurring in the studied Neoarchean samples. Also the optical and SEM images of polished and etched platelets of permineralised Lake Van microbialites are strikingly similar (Fig. 2d-f). Similarly as in modern cyanobacterial and other microbial mats, the process of early post mortem mineralisation, in the case of the Nauga Formation, was most probably associated with the action of heterotrophic bacteria upon the dead cyanobacterial biomass. Heterotrophic bacteria occupying EPS layers of living and dead cyanobacterial cells have the ability to bind various ions and may serve as nucleation centres for a variety of m

Kazmierczak, J.; Altermann, W.; Kremer, B.; Kempe, S.; Eriksson, P. G.

2008-09-01

326

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

327

State of knowledge and concerns on cyanobacterial blooms and cyanotoxins.  

PubMed

Cyanobacteria are ubiquitous microorganisms considered as important contributors to the formation of Earth's atmosphere and nitrogen fixation. However, they are also frequently associated with toxic blooms. Indeed, the wide range of hepatotoxins, neurotoxins and dermatotoxins synthesized by these bacteria is a growing environmental and public health concern. This paper provides a state of the art on the occurrence and management of harmful cyanobacterial blooms in surface and drinking water, including economic impacts and research needs. Cyanobacterial blooms usually occur according to a combination of environmental factors e.g., nutrient concentration, water temperature, light intensity, salinity, water movement, stagnation and residence time, as well as several other variables. These environmental variables, in turn, have promoted the evolution and biosynthesis of strain-specific, gene-controlled metabolites (cyanotoxins) that are often harmful to aquatic and terrestrial life, including humans. Cyanotoxins are primarily produced intracellularly during the exponential growth phase. Release of toxins into water can occur during cell death or senescence but can also be due to evolutionary-derived or environmentally-mediated circumstances such as allelopathy or relatively sudden nutrient limitation. Consequently, when cyanobacterial blooms occur in drinking water resources, treatment has to remove both cyanobacteria (avoiding cell lysis and subsequent toxin release) and aqueous cyanotoxins previously released. Cells are usually removed with limited lysis by physical processes such as clarification or membrane filtration. However, aqueous toxins are usually removed by both physical retention, through adsorption on activated carbon or reverse osmosis, and chemical oxidation, through ozonation or chlorination. While the efficient oxidation of the more common cyanotoxins (microcystin, cylindrospermopsin, anatoxin and saxitoxin) has been extensively reported, the chemical and toxicological characterization of their by-products requires further investigation. In addition, future research should also investigate the removal of poorly considered cyanotoxins (?-methylamino-alanine, lyngbyatoxin or aplysiatoxin) as well as the economic impact of blooms. PMID:23892224

Merel, Sylvain; Walker, David; Chicana, Ruth; Snyder, Shane; Baurès, Estelle; Thomas, Olivier

2013-09-01

328

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

SciTech Connect

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

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

1984-01-01

329

Freshwater Pollution and Treatment  

NSDL National Science Digital Library

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

Michael Griffin (Brogden Middle School)

2008-08-01

330

Acidification of freshwaters  

SciTech Connect

This volume gives an account that draws not only on the main branches of chemistry but also on soil physics, chemistry, hydrology, meteorology, geography, geology, plant physiology, soil microbiology and zoology. The author examine the numerous interacting physical, chemical, and biological, processes that regulate the acidity of freshwaters, a phenomenon that has various causes, including precipitation; acidifying pollutions; and the interaction of plants, soils and water. The relative importance of the different processes is examined.

Cresser, M.S.; Edwards, A.C.

1987-01-01

331

Foraging trade-offs and resource patchiness: theory and experiments with a freshwater snail community  

Microsoft Academic Search

Empirical results concerning a freshwater snail community are interpreted using a two- species consumer model that incorporates resource structure. Behavioural-scale measurements on a guild of five species of freshwater pond snails (Mollusca: Pulmonata) indicate a trade-off between the ability to utilize a patch's resource and the ability to quickly find new resource patches. Community-level experiments demonstrate that both species richness

Jonathan M. Chase; Will G. Wilson; Shane A. Richards

2001-01-01

332

Influence of local and global environmental parameters on the composition of cyanobacterial mats in a tropical lagoon.  

PubMed

Cyanobacteria-dominated microbial mat communities thrive widely and year round in coral reefs and tropical lagoons, with periodic massive development of benthic blooms. We studied the diversity and spatiotemporal variation of the cyanobacterial dominance in mats of the shallow lagoon of La Réunion Island in the Indian Ocean by means of denaturing gradient gel electrophoresis and cloning-sequencing approaches targeting the 16S rRNA gene, combined with macromorphological and micromorphological characterization of corresponding phenotypes. The mat-forming cyanobacteria were highly diversified with at least 67 distinct operational taxonomic units identified in the lagoon, encompassing the entire morphological spectrum of the phylum Cyanobacteria, but with striking dominance of Oscillatoriales and Nostocales. It appeared also that selective pressures acting at different geographical scales have an influence on the structure and composition of these mats dominated by cyanobacteria. First, large changes were observed in their diversity and composition in relation to local changes occurring in their environment. Second, from the data obtained on the richness and composition of the mats and from the comparison with similar studies in the world, tropical mats seem to display wider cyanobacterial richness than in temperate and cold areas. Moreover, these tropical mats share more species with mats in other tropical regions than with those in temperate and cold climatic regions, suggesting that marine cyanobacteria in biofilms and mats display a biogeographic structure. PMID:25260923

Echenique-Subiabre, Isidora; Villeneuve, Aurélie; Golubic, Stjepko; Turquet, Jean; Humbert, Jean-François; Gugger, Muriel

2015-02-01

333

Nitrogenase activities associated with macrophytes from a lacustrine and a freshwater estuarine habitat  

Microsoft Academic Search

The distribution and activities of diazotrophic epiphytes among and between species of freshwater emergent, submersed, and floating macrophytes were examined. We compared the aerobic and anaerobic macrophyte-associated nitrogenase activities from an urban lake, East Twin Lake, and an agriculturally-impacted freshwater estuary, Old Woman Creek Estuary, both in northern Ohio, USA. Epiphyte nitrogenase activity (NA) associated with macrophyte stems, petioles, or

Conrad E. Wickstrom; Julie L. Corkran

1997-01-01

334

Biodegradation of multiple cyanobacterial metabolites in drinking water supplies.  

PubMed

The fate of multiple cyanobacterial metabolites was assessed in two Australian source waters. The saxitoxins were the only metabolites shown to be non-biodegradable in Myponga Reservoir water, while microcystin-LR (MCLR) and geosmin were biodegradable in this water source. Likewise, cylindrospermopsin (CYN) was shown to be biodegradable in River Murray water. The order of ease of biodegradability followed the trend: MCLR>CYN>geosmin>saxitoxins. Biodegradation of the metabolites was affected by temperature and seasonal variations with more rapid degradation at 24°C and during autumn compared with 14°C and during winter. A microcystin-degrading bacterium was isolated and shown to degrade four microcystin variants within 4 h. This bacterium, designated as TT25, was shown to be 99% similar to a Sphingopyxis sp. based on a 16S rRNA gene fragment. Isolate TT25 was shown to contain a homologue of the mlrA gene; the sequence of which was 99% similar to that of a previously reported microcystin-degrader. Furthermore, isolate TT25 could degrade the microcystins in the presence of copper sulphate (0.5 mg L(-1) as Cu(2+)) which is advantageous for water authorities dosing such algicides into water bodies to control cyanobacterial blooms. PMID:22386459

Ho, Lionel; Tang, Tim; Monis, Paul T; Hoefel, Daniel

2012-06-01

335

2-Methylhopanoids as biomarkers for cyanobacterial oxygenic photosynthesis  

NASA Astrophysics Data System (ADS)

Oxygenic photosynthesis is widely accepted as the most important bioenergetic process happening in Earth's surface environment. It is thought to have evolved within the cyanobacterial lineage, but it has been difficult to determine when it began. Evidence based on the occurrence and appearance of stromatolites and microfossils indicates that phototrophy occurred as long ago as 3,465Myr although no definite physiological inferences can be made from these objects. Carbon isotopes and other geological phenomena, provide clues but are also equivocal. Biomarkers are potentially useful because the three domains of extant life-Bacteria, Archaea and Eukarya-have signature membrane lipids with recalcitrant carbon skeletons. These lipids turn into hydrocarbons in sediments and can be found wherever the recordis sufficiently well preserved. Here we show that 2-methylbacteriohopanepolyols occur in a high proportion of cultured cyanobacteria and cyanobacterial mats. Their 2-methylhopane hydrocarbon derivatives are abundant in organic-rich sediments as old as 2,500Myr. These biomarkers may help constrain the age of the oldest cyanobacteria and the advent of oxygenic photosynthesis. They could also be used to quantify the ecological importance of cyanobacteria through geological time.

Summons, Roger E.; Jahnke, Linda L.; Hope, Janet M.; Logan, Graham A.

1999-08-01

336

Toxicity of harmful cyanobacterial blooms to bream and roach.  

PubMed

Aquatic ecosystems are facing increasing environmental pressures, leading to an increasing frequency of cyanobacterial Harmful Algal Blooms (cHABs) that have emerged as a worldwide concern due to their growing frequency and their potential toxicity to the fauna that threatens the functioning of ecosystems. Cyanobacterial blooms raise concerns due to the fact that several strains produce potent bioactive or toxic secondary metabolites, such as the microcystins (MCs), which are hepatotoxic to vertebrates. These strains of cyanobacteria may be potentially toxic to fish via gastrointestinal ingestion and also by direct absorption of the toxin MC from the water. The purpose of our study was to investigate toxic effects observed in fish taken from several lakes in the Ile-de-France region, where MCs-producing blooms occur. This study comprises histological studies and the measurement of MC concentrations in various organs. The histological findings are similar to those obtained following laboratory exposure of medaka fish to MCs: hepatic lesions predominate and include cell lysis and cell detachment. MC concentrations in the organs revealed that accumulation was particularly high in the digestive tract and the liver, which are known to be classical targets of MCs. In contrast concentrations were very low in the muscles. Differences in the accumulation of MC variants produced by blooms indicate that in order to more precisely evaluate the toxic potential of a specific bloom it is necessary not only to consider the concentration of toxins, but also the variants produced. PMID:23732128

Trinchet, Isabelle; Cadel-Six, Sabrina; Djediat, Chakib; Marie, Benjamin; Bernard, Cécile; Puiseux-Dao, Simone; Krys, Sophie; Edery, Marc

2013-09-01

337

Selecting Reliable and Robust Freshwater Macroalgae for Biomass Applications  

PubMed Central

Intensive cultivation of freshwater macroalgae is likely to increase with the development of an algal biofuels industry and algal bioremediation. However, target freshwater macroalgae species suitable for large-scale intensive cultivation have not yet been identified. Therefore, as a first step to identifying target species, we compared the productivity, growth and biochemical composition of three species representative of key freshwater macroalgae genera across a range of cultivation conditions. We then selected a primary target species and assessed its competitive ability against other species over a range of stocking densities. Oedogonium had the highest productivity (8.0 g ash free dry weight m?2 day?1), lowest ash content (3–8%), lowest water content (fresh weigh: dry weight ratio of 3.4), highest carbon content (45%) and highest bioenergy potential (higher heating value 20 MJ/kg) compared to Cladophora and Spirogyra. The higher productivity of Oedogonium relative to Cladophora and Spirogyra was consistent when algae were cultured with and without the addition of CO2 across three aeration treatments. Therefore, Oedogonium was selected as our primary target species. The competitive ability of Oedogonium was assessed by growing it in bi-cultures and polycultures with Cladophora and Spirogyra over a range of stocking densities. Cultures were initially stocked with equal proportions of each species, but after three weeks of growth the proportion of Oedogonium had increased to at least 96% (±7 S.E.) in Oedogonium-Spirogyra bi-cultures, 86% (±16 S.E.) in Oedogonium-Cladophora bi-cultures and 82% (±18 S.E.) in polycultures. The high productivity, bioenergy potential and competitive dominance of Oedogonium make this species an ideal freshwater macroalgal target for large-scale production and a valuable biomass source for bioenergy applications. These results demonstrate that freshwater macroalgae are thus far an under-utilised feedstock with much potential for biomass applications. PMID:23717561

Lawton, Rebecca J.; de Nys, Rocky; Paul, Nicholas A.

2013-01-01

338

Selecting reliable and robust freshwater macroalgae for biomass applications.  

PubMed

Intensive cultivation of freshwater macroalgae is likely to increase with the development of an algal biofuels industry and algal bioremediation. However, target freshwater macroalgae species suitable for large-scale intensive cultivation have not yet been identified. Therefore, as a first step to identifying target species, we compared the productivity, growth and biochemical composition of three species representative of key freshwater macroalgae genera across a range of cultivation conditions. We then selected a primary target species and assessed its competitive ability against other species over a range of stocking densities. Oedogonium had the highest productivity (8.0 g ash free dry weight m?² day?¹), lowest ash content (3-8%), lowest water content (fresh weigh: dry weight ratio of 3.4), highest carbon content (45%) and highest bioenergy potential (higher heating value 20 MJ/kg) compared to Cladophora and Spirogyra. The higher productivity of Oedogonium relative to Cladophora and Spirogyra was consistent when algae were cultured with and without the addition of CO? across three aeration treatments. Therefore, Oedogonium was selected as our primary target species. The competitive ability of Oedogonium was assessed by growing it in bi-cultures and polycultures with Cladophora and Spirogyra over a range of stocking densities. Cultures were initially stocked with equal proportions of each species, but after three weeks of growth the proportion of Oedogonium had increased to at least 96% (±7 S.E.) in Oedogonium-Spirogyra bi-cultures, 86% (±16 S.E.) in Oedogonium-Cladophora bi-cultures and 82% (±18 S.E.) in polycultures. The high productivity, bioenergy potential and competitive dominance of Oedogonium make this species an ideal freshwater macroalgal target for large-scale production and a valuable biomass source for bioenergy applications. These results demonstrate that freshwater macroalgae are thus far an under-utilised feedstock with much potential for biomass applications. PMID:23717561

Lawton, Rebecca J; de Nys, Rocky; Paul, Nicholas A

2013-01-01

339

Effects of pollution on freshwater organisms  

SciTech Connect

This review includes subjects in last year's reviews on effects of pollution on freshwater invertebrates and effects of pollution on freshwater fish and amphibians. This review also includes information on the effects of pollution on freshwater plants. 625 references.

Phipps, G.L.; Harden, M.J.; Leonard, E.N.; Roush, T.H; Spehar, D.L.; Stephan, C.E.; Pickering, Q.H.; Buikema, A.L. Jr.

1984-06-01

340

Carassius gibelio in Greece: the dominant naturalised invader of freshwaters  

Microsoft Academic Search

Ichthyofauna in the Hellenic freshwaters is quite diverse consisted of 161 species (including 28 non-natives), out of the\\u000a 546 native species in Pan-European level. However, the status of many aquatic ecosystems is currently degraded as a result\\u000a of a variety of anthropogenic impacts. This has direct reflection on the conservation status of the indigenous and native\\u000a fish species whose populations

Costas Perdikaris; Anna Ergolavou; Evangelia Gouva; Cosmas Nathanailides; Athanasios Chantzaropoulos; Ioannis Paschos

341

Biotechnological screening of microalgal and cyanobacterial strains for biogas production and antibacterial and antifungal effects.  

PubMed

Microalgae and cyanobacteria represent a valuable natural resource for the generation of a large variety of chemical substances that are of interest for medical research, can be used as additives in cosmetics and food production, or as an energy source in biogas plants. The variety of potential agents and the use of microalgae and cyanobacteria biomass for the production of these substances are little investigated and not exploited for the market. Due to the enormous biodiversity of microalgae and cyanobacteria, they hold great promise for novel products. In this study, we investigated a large number of microalgal and cyanobacterial strains from the Culture Collection of Algae at Göttingen University (SAG) with regard to their biomass and biogas production, as well antibacterial and antifungal effects. Our results demonstrated that microalgae and cyanobacteria are able to generate a large number of economically-interesting substances in different quantities dependent on strain type. The distribution and quantity of some of these components were found to reflect phylogenetic relationships at the level of classes. In addition, between closely related species and even among multiple isolates of the same species, the productivity may be rather variable. PMID:24957031

Mudimu, Opayi; Rybalka, Nataliya; Bauersachs, Thorsten; Born, Jens; Friedl, Thomas; Schulz, Rüdiger

2014-01-01

342

Biotechnological Screening of Microalgal and Cyanobacterial Strains for Biogas Production and Antibacterial and Antifungal Effects  

PubMed Central

Microalgae and cyanobacteria represent a valuable natural resource for the generation of a large variety of chemical substances that are of interest for medical research, can be used as additives in cosmetics and food production, or as an energy source in biogas plants. The variety of potential agents and the use of microalgae and cyanobacteria biomass for the production of these substances are little investigated and not exploited for the market. Due to the enormous biodiversity of microalgae and cyanobacteria, they hold great promise for novel products. In this study, we investigated a large number of microalgal and cyanobacterial strains from the Culture Collection of Algae at Göttingen University (SAG) with regard to their biomass and biogas production, as well antibacterial and antifungal effects. Our results demonstrated that microalgae and cyanobacteria are able to generate a large number of economically-interesting substances in different quantities dependent on strain type. The distribution and quantity of some of these components were found to reflect phylogenetic relationships at the level of classes. In addition, between closely related species and even among multiple isolates of the same species, the productivity may be rather variable. PMID:24957031

Mudimu, Opayi; Rybalka, Nataliya; Bauersachs, Thorsten; Born, Jens; Friedl, Thomas; Schulz, Rüdiger

2014-01-01

343

Stream trees: a statistical method for mapping genetic differences between populations of freshwater organisms to the sections of streams that connect them  

Microsoft Academic Search

Statistical approaches for studying the spatial distribution of genetic diversity that assume that organisms move through a two-dimensional landscape are not well suited to study populations of freshwater fish. We present a new statisti- cal method for mapping genetic differences among populations of freshwater fish to the sections of streams that connect them. The method is useful for freshwater species

Steven T. Kalinowski; Michael H. Meeuwig; Shawn R. Narum; Mark L. Taper

2008-01-01

344

Viral encephalopathy and retinopathy outbreak in freshwater fish farmed in Italy.  

PubMed

Viral encephalopathy and retinopathy (VER), otherwise known as viral nervous necrosis (VNN), is a neuropathological condition affecting > 40 species of fish. Although VER affects mainly marine fish, the disease has also been detected in certain species reared in freshwater environments. There are relatively few reports concerning the disease in freshwater species, and there is not much information on clinical signs. Nevertheless, the most common clinical findings reported from affected freshwater species are consistent with the typical signs observed in marine species. In this paper we describe the main clinical signs and the laboratory results associated with the detection of a betanodavirus in hybrid striped bass x white bass (Morone saxatilis x Morone chrysops) and largemouth bass Micropterus salmoides, reared in a freshwater environment. We also detected the virus by real-time PCR and isolated it in cell culture from a batch of pike-perch Sander lucioperca farmed in the same system. PMID:21991664

Bovo, G; Gustinelli, A; Quaglio, F; Gobbo, F; Panzarin, V; Fusaro, A; Mutinelli, F; Caffara, M; Fioravanti, M L

2011-08-29

345

Cyanobacterial toxins: modes of actions, fate in aquatic and soil ecosystems, phytotoxicity and bioaccumulation in agricultural crops.  

PubMed

The occurrence of harmful cyanobacterial blooms in surface waters is often accompanied by the production of a variety of cyanotoxins. These toxins are designed to target in humans and animals specific organs on which they act: hepatotoxins (liver), neurotoxins (nervous system), cytotoxic alkaloids, and dermatotoxins (skin), but they often have important side effects too. When introduced into the soil ecosystem by spray irrigation of crops they may affect the same molecular pathways in plants having identical or similar target organs, tissues, cells or biomolecules. There are also several indications that terrestrial plants, including food crop plants, can bioaccumulate cyanotoxins and present, therefore, potential health hazards for human and animals. The number of publications concerned with phytotoxic effects of cyanotoxins on agricultural plants has increased recently. In this review, we first examine different cyanotoxins and their modes of actions in humans and mammals and occurrence of target biomolecules in vegetable organisms. Then we present environmental concentrations of cyanotoxins in freshwaters and their fate in aquatic and soil ecosystems. Finally, we highlight bioaccumulation of cyanotoxins in plants used for feed and food and its consequences on animals and human health. Overall, our review shows that the information on the effects of cyanotoxins on non-target organisms in the terrestrial environment is particularly scarce, and that there are still serious gaps in the knowledge about the fate in the soil ecosystems and phytotoxicity of these toxins. PMID:24012139

Corbel, Sylvain; Mougin, Christian; Bouaïcha, Noureddine

2014-02-01

346

Double strand breaks and cell-cycle arrest induced by the cyanobacterial toxin cylindrospermopsin in HepG2 cells.  

PubMed

The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the mechanisms of CYN toxicity and genotoxicity are not well understood. In the present study CYN induced formation of DNA double strand breaks (DSBs), after prolonged exposure (72 h), in human hepatoma cells, HepG2. CYN (0.1-0.5 µg/mL, 24-96 h) induced morphological changes and reduced cell viability in a dose and time dependent manner. No significant increase in lactate dehydrogenase (LDH) leakage could be observed after CYN exposure, indicating that the reduction in cell number was due to decreased cell proliferation and not due to cytotoxicity. This was confirmed by imunocytochemical analysis of the cell-proliferation marker Ki67. Analysis of the cell-cycle using flow-cytometry showed that CYN has an impact on the cell cycle, indicating G0/G1 arrest after 24 h and S-phase arrest after longer exposure (72 and 96 h). Our results provide new evidence that CYN is a direct acting genotoxin, causing DSBs, and these facts need to be considered in the human health risk assessment. PMID:23966038

Alja, Štraser; Filipi?, Metka; Novak, Matjaž; Žegura, Bojana

2013-08-01

347

Double Strand Breaks and Cell-Cycle Arrest Induced by the Cyanobacterial Toxin Cylindrospermopsin in HepG2 Cells  

PubMed Central

The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the mechanisms of CYN toxicity and genotoxicity are not well understood. In the present study CYN induced formation of DNA double strand breaks (DSBs), after prolonged exposure (72 h), in human hepatoma cells, HepG2. CYN (0.1–0.5 µg/mL, 24–96 h) induced morphological changes and reduced cell viability in a dose and time dependent manner. No significant increase in lactate dehydrogenase (LDH) leakage could be observed after CYN exposure, indicating that the reduction in cell number was due to decreased cell proliferation and not due to cytotoxicity. This was confirmed by imunocytochemical analysis of the cell-proliferation marker Ki67. Analysis of the cell-cycle using flow-cytometry showed that CYN has an impact on the cell cycle, indicating G0/G1 arrest after 24 h and S-phase arrest after longer exposure (72 and 96 h). Our results provide new evidence that CYN is a direct acting genotoxin, causing DSBs, and these facts need to be considered in the human health risk assessment. PMID:23966038

Štraser, Alja; Filipi?, Metka; Novak, Matjaž; Žegura, Bojana

2013-01-01

348

New data on freshwater psammic Gastrotricha from Brazil.  

PubMed

Current knowledge of freshwater gastrotrich fauna from Brazil is underestimated as only two studies are available. The present communication is a taxonomic account of the first-ever survey of freshwater Gastrotricha in Minas Gerais State. Samplings were carried out yielding six species of three Chaetonotidae genera: Aspidiophorus cf. pleustonicus, Ichthydium cf. chaetiferum, Chaetonotus acanthocephalus, Chaetonotus heideri, Chaetonotus cf. succinctus, Chaetonotus sp., and also an undescribed species belonging to the genus Redudasys (incertae sedis): this is the first finding of specimens of Redudasys outside of original type locality. These preliminary observations suggest that the knowledge of the biodiversity of Gastrotricha in the Minas Gerais State, as well as in the whole Brazil, will certainly increase as further investigations are undertaken, and that freshwater Macrodasyida may be more common than previously thought. PMID:21594197

Garraffoni, André R S; Araujo, Thiago Q; Lourenço, Anete P; Balsamo, Maria

2010-01-01

349

New data on freshwater psammic Gastrotricha from Brazil  

PubMed Central

Abstract Current knowledge of freshwater gastrotrich fauna from Brazil is underestimated as only two studies are available. The present communication is a taxonomic account of the first-ever survey of freshwater Gastrotricha in Minas Gerais State. Samplings were carried out yielding six species of three Chaetonotidae genera: Aspidiophorus cf. pleustonicus, Ichthydium cf. chaetiferum, Chaetonotus acanthocephalus, Chaetonotus heideri, Chaetonotus cf. succinctus, Chaetonotus sp., and also an undescribed species belonging to the genus Redudasys (incertae sedis): this is the first finding of specimens of Redudasys outside of original type locality. These preliminary observations suggest that the knowledge of the biodiversity of Gastrotricha in the Minas Gerais State, as well as in the whole Brazil, will certainly increase as further investigations are undertaken, and that freshwater Macrodasyida may be more common than previously thought. PMID:21594197

Garraffoni, André R. S.; Araujo, Thiago Q.; Lourenço, Anete P.; Balsamo, Maria

2010-01-01

350

Activated chemical defenses suppress herbivory on freshwater red algae.  

PubMed

The rapid life cycles of freshwater algae are hypothesized to suppress selection for chemical defenses against herbivores, but this notion remains untested. Investigations of chemical defenses are rare for freshwater macrophytes and absent for freshwater red algae. We used crayfish to assess the palatability of five freshwater red algae relative to a palatable green alga and a chemically defended aquatic moss. We then assessed the roles of structural, nutritional, and chemical traits in reducing palatability. Both native and non-native crayfish preferred the green alga Cladophora glomerata to four of the five red algae. Batrachospermum helminthosum, Kumanoa holtonii, and Tuomeya americana employed activated chemical defenses that suppressed feeding by 30-60 % following damage to algal tissues. Paralemanea annulata was defended by its cartilaginous structure, while Boldia erythrosiphon was palatable. Activated defenses are thought to reduce ecological costs by expressing potent defenses only when actually needed; thus, activation might be favored in freshwater red algae whose short-lived gametophytes must grow and reproduce rapidly over a brief growing season. The frequency of activated chemical defenses found here (three of five species) is 3-20× higher than for surveys of marine algae or aquatic vascular plants. If typical for freshwater red algae, this suggests that (1) their chemical defenses may go undetected if chemical activation is not considered and (2) herbivory has been an important selective force in the evolution of freshwater Rhodophyta. Investigations of defenses in freshwater rhodophytes contribute to among-system comparisons and provide insights into the generality of plant-herbivore interactions and their evolution. PMID:23011851

Goodman, Keri M; Hay, Mark E

2013-04-01

351

United Nations Environment Programme: Freshwater  

NSDL National Science Digital Library

This portal provides access to information on equitable and sustainable management of freshwater resources around the world. Topics include water scarcity, irrigated agriculture, water and sanitation, water quality, groundwater, transboundary water management, water and ecosystems, floods and droughts, and urban water. There are also case studies, global assessments of freshwater resources, policy documents, and information on conferences and other events.

352

Gregariousness versus solitude: another look at parasite faunal richness in Canadian freshwater fishes  

Microsoft Academic Search

Recently Poulin (1991), using published data on Canadian freshwater fishes (60 species, three families), concluded that there is no difference in parasite species numbers between solitary and social species. Nor could he associate parasite diversity to host size, age or range of distribution. Analysing Poulin's data with somewhat differing methods I reached different conclusions. Recognising that reported parasite species number

Esa Ranta

1992-01-01

353

Terrestrial and freshwater Tardigrada of the Americas.  

PubMed

This paper provides a comprehensive list of the freshwater and terrestrial tardigrade fauna reported from the Americas (North America, South America, Central America and the West Indies), their distribution in the Americas, and the substrates from which they have been reported. Data were obtained from 316 published references. Authors' identifications were accepted at face value unless subsequently amended. Taxa were assigned to sub-national units (states, provinces, etc.). Many areas, in particular large portions of Central America and the West Indies, have no reported tardigrade fauna.        The presence of 54 genera and 380 species has been reported for the Americas; 245 species have been collected in the Nearctic ecozone and 251 in the Neotropical ecozone. Among the tardigrade species found in the Americas, 52 are currently considered cosmopolitan, while 153 species have known distributions restricted to the Americas. Based on recent taxonomic revision of the genus Milnesium, the vast majority of records of M. tardigradum in the Americas should now be reassigned to Milnesium tardigradum sensu lato, either because the provided description differs from M. tardigradum sensu stricto or because insufficient description is provided to make a determination; the remainder should be considered Milnesium cf. tardigradum.        Most terrestrial tardigrade sampling in the Americas has focused on cryptogams (mosses, lichens and liverworts); 90% of the species have been collected in such substrates. The proportion of species collected in other habitats is lower: 14% in leaf litter, 20% in soil, and 24% in aquatic samples (in other terrestrial substrates the proportion never exceeds 5%). Most freshwater tardigrades have been collected from aquatic vegetation and sediment. For nine species in the Americas no substrates have been reported.  PMID:25113595

Meyer, Harry A

2013-01-01

354

DETOXIFICATION OF CYANOBACTERIAL TOXIN - CONTAMINATED WATER USING TIO2 PHOTOCATALYTIC FILMS  

EPA Science Inventory

Cyanobacterial harmfal algal blooms (CyanoHABs) often produce undesirable color, odor and taste and more importantly, potent toxins that can cause chronic, acute and acute letha poisonings to wild and domestic animals and humans...

355

Cyanobacterium sp. host cell and vector for production of chemical compounds in cyanobacterial cultures  

SciTech Connect

A cyanobacterial host cell, Cyanobacterium sp., that harbors at least one recombinant gene for the production of a chemical compounds is provided, as well as vectors derived from an endogenous plasmid isolated from the cell.

Piven, Irina; Friedrich, Alexandra; Duhring, Ulf; Uliczka, Frank; Baier, Kerstin; Inaba, Masami; Shi, Tuo; Wang, Kui; Enke, Heike; Kramer, Dan

2014-09-30

356

Detection of microcystins in Pamvotis lake water and assessment of cyanobacterial bloom toxicity  

Microsoft Academic Search

Lake Pamvotis is a shallow, eutrophic Mediterranean lake with ecological significance. This paper deals with the evaluation\\u000a of cyanobacterial toxicity in Lake Pamvotis. ELISA and HPLC revealed the presence of significant amounts of MCYST-LR. Danio rerio bioassay confirmed the toxic nature of the bloom. Cyanobacterial extracts had adverse toxic effects on development of D. rerio. Also, it was shown that

Theodoti Papadimitriou; Euthimia Armeni; Constantine D. Stalikas; Ifigeneia Kagalou; Ioannis D. Leonardos

357

The Effects of Cyanobacterial Exudates on Bacterial Growth and Biodegradation of Organic Contaminants  

Microsoft Academic Search

The pulp and paper industry largely depends on the biodegradation activities of heterotrophic bacteria to remove organic contaminants\\u000a in wastewater prior to discharge. Our recent discovery of extensive cyanobacterial communities in pulp and paper waste treatment\\u000a systems led us to investigate the potential impacts of cyanobacterial exudates on growth and biodegradation efficiency of\\u000a three bacterial heterotrophs. Each of the three

A. E. Kirkwood; C. Nalewajko; R. R. Fulthorpe

2006-01-01

358

Cyanobacterial N2 fixation in presence of nitrogen fertilizers.  

PubMed

Anabaena oryzae ARM 570 was examined for its growth (chlorophyll and protein), heterocyst frequency, nitrogenase (acetylene reduction) activity, ammonia excretion, and glutamine synthetase and nitrate reductase in response to two levels of urea-N vis-à-vis N2-N. Growth of cyanobacterium increased with duration of incubation. Reduction in heterocyst frequency (40%) was observed at 30 ppm of urea-N, whereas at 60 ppm of urea-N, filaments were completely devoid of heterocysts and no nitrogenase activity was observed. Maximum excretion of ammonia occurred at 30 ppm of urea-N, which was concomitant with minimum glutamine synthetase activity. These results suggested that A. oryzae could be effectively utilized in cyanobacterial biofertilizer programme even in the presence of combined nitrogen, for improving N-budget in rice cultivation. PMID:12597560

Mekonnen, A E; Prasanna, Radha; Kaushik, B D

2002-07-01

359

HEAVY METAL ACCUMULATION IN SEDIMENT AND FRESHWATER FISH IN U.S. ARCTIC LAKES  

EPA Science Inventory

Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus]} were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated...

360

A GUIDE TO THE FRESHWATER TUBIFICIDAE (ANNELIDA: CLITELLATA: OLIGOCHAETA) OF NORTH AMERICA  

EPA Science Inventory

In North America, the freshwater annelid worms (Clitellata: Oligochaeta), belonging in the family Tubificidae, are composed of 18 genera, 54 species, one subspecies, and several variant forms. All taxa can be identified by external and internal morphological features. This guide ...

361

Conservation planning for connectivity across marine, freshwater, and terrestrial realms  

Microsoft Academic Search

Conservation plans are usually developed for regions that encompass only one environmental realm (terrestrial, freshwater or marine) because of logistical, institutional and political constraints. This is inadequate because these realms often interact through processes that form, utilize and maintain interfaces or connections, which are essential for the persistence of some species and ecosystem functions. We present a conceptual framework for

Maria Beger; Hedley S. Grantham; Robert L. Pressey; Kerrie A. Wilson; Eric L. Peterson; Daniel Dorfman; Peter J. Mumby; Reinaldo Lourival; Daniel R. Brumbaugh; Hugh P. Possingham

2010-01-01

362

Freshwater mollusc biodiversity and conservation in two stressed Mediterranean basins  

Microsoft Academic Search

This paper reviews the environmental factors that influence biodiversity of freshwater mollusc communities and conservation status of watercourses in two Mediterranean acid mine drainage-impacted basins of the southern Iberian Peninsula. We found 17 mollusc species: 14 gastropods (10 native and 4 introduced) and 3 bivalves. We found five distribution patterns: native headwater (Arganiella wolfi, Stagnicola palustris, Unio delphinus, Pisidium casertanum

Juan Carlos Pérez-Quintero

2011-01-01

363

Ship noise and cortisol secretion in European freshwater fishes  

Microsoft Academic Search

Underwater noise pollution is a growing problem in aquatic environments and as such may be a major source of stress for fish. In the present study, we addressed the effects of ship noise and continuous Gaussian noise on adrenal activity in three European freshwater species. Underwater ship noise recorded in the Danube River and two Austrian lakes was played back

Lidia Eva Wysocki; John P. Dittami; Friedrich Ladich

2006-01-01

364

A bioaccumulation bioassay for freshwater sediments  

USGS Publications Warehouse

A laboratory bioassay is described for determining the bioavailability of contaminants from freshwater sediments. The bioassay consists of 10-d exposures to whole sediments under flow-through conditions. After testing five species, the fathead minnow (Pimephales promelas) and the earthworm (Lubricus terrestris) were recommended for use in the test. When the availability of polychlorinated biphenyls (PCBs), Hg and Zn from Great Lakes sediments was examined in laboratory exposures, only the PCBs were accumulated. A field validation study demonstrated that the magnitude of accumulation in laboratory exposures was similar to that in organisms caged in the field. A protocol is recommended for using the test as a standardized bioaccumulation bioassay.

Mac, Michael J.; Noguchi, George E.; Hesselberg, Robert J.; Edsall, Carol C.; Shoesmith, John A.; Bowker, James D.

1990-01-01

365

Freshwater aspects of anadromous salmonid enhancement  

USGS Publications Warehouse

Freshwater enhancement of anadromous salmonid populations has been practiced in the United States and Canada since the late 1800's. Reduction of natural spawning habitat and increasing fishing pressure make artificial enhancement a possible alternative to declining populations. Enhancement of anadromous salmonids involved improvement of the natural environment and reducing natural mortality. Methods of enhancement include fishways, spawning and rearing channels, stream rehabilitation, lake fertilization, environmental management, and artificial propagation techniques. Five Pacific salmon species and steelhead trout are commonly enhanced, primarily in watershed entering the Pacific Ocean and Great Lakes. Enhancement efforts contribute heavily to a commercial and sport industry realizing over $1.5 billion.

Gould, Rowan W.

1982-01-01

366

Benthic Marine Cyanobacterial Mat Ecosystems: Biogeochemistry and Biomarkers  

NASA Technical Reports Server (NTRS)

Cyanobacterial mats are complete ecosystems that can include processes of primary production, diagenesis and lithification. Light sustains oxygenic photosynthesis, which in turn provides energy, organic matter and oxygen to the community. Due to both absorption and scattering phenomena, incident light is transformed with depth in the mat, both in intensity and spectral composition. Mobile photo synthesizers optimize their position with respect to this light gradient. When photosynthesis ceases at night, the upper layers of the mat become reduced and sulfidic. Counteracting gradients of oxygen and sulfide combine to provide daily-contrasting environments separated on a scale of a few mm. The functional complexity of mats, coupled with the highly proximal and ordered spatial arrangement of biota, offers the potential for a staggering number of interactions. At a minimum, the products of each functional group of microorganisms affect the other groups both positively and negatively. For example, cyanobacteria generate organic matter (potential substrates) but also oxygen (a toxin for many anaerobes). Anaerobic activity recycles nutrients to the photosynthesizers but also generates potentially toxic sulfide. The combination of benefits and hazards of light, oxygen and sulfide promotes the allocation of the various essential mat processes between light and dark periods, and to various depths in the mat. Observations of mats have produced numerous surprises. For example, obligately anaerobic processes can occur in the presence of abundant oxygen, highly reduced gases are produced in the presence of abundant sulfate, meiofauna thrive at high sulfide concentrations, and the mats' constituent populations respond to environmental changes in complex ways. While photosynthetic bacteria dominate the biomass and productivity of the mat, nonphotosynthetic, anaerobic processes constitute the ultimate biological filter on the ecosystem's emergent biosignatures, including those sedimentary textures, organic compounds, and minerals that enter the fossil record. The ability of cyanobacterial mats to channel abundant solar energy into the creation and maintenance of complex structures and processes has created a multitude of consequences, both for sedimentation and for the early evolution of our biosphere.

DesMarais, David J.; DeVincenzi, Donald (Technical Monitor)

2001-01-01

367

Microalgal and cyanobacterial cultivation: the supply of nutrients.  

PubMed

Microalgae and cyanobacteria are a promising new source of biomass that may complement agricultural crops to meet the increasing global demand for food, feed, biofuels and chemical production. Microalgae and cyanobacteria cultivation does not interfere directly with food production, but care should be taken to avoid indirect competition for nutrient (fertilizer) supply. Microalgae and cyanobacteria production requires high concentrations of essential nutrients (C,N,P,S,K,Fe, etc.). In the present paper the application of nutrients and their uptake by microalgae and cyanobacteria is reviewed. The main focus is on the three most significant nutrients, i.e. carbon, nitrogen and phosphorus; however other nutrients are also reviewed. Nutrients are generally taken up in the inorganic form, but several organic forms of them are also assimilable. Some nutrients do not display any inhibition effect on microalgal or cyanobacterial growth, while others, such as NO2 or NH3 have detrimental effects when present in high concentrations. Nutrients in the gaseous form, such as CO2 and NO face a major limitation which is related mainly to their mass transfer from the gaseous to the liquid state. Since the cultivation of microalgae and cyanobacteria consumes considerable quantities of nutrients, strategies to improve the nutrient application efficiency are needed. Additionally, a promising strategy to improve microalgal and cyanobacterial production sustainability is the utilization of waste streams by recycling of waste nutrients. However, major constraints of using waste streams are the reduction of the range of the biomass applications due to production of contaminated biomass and the possible low bio-availability of some nutrients. PMID:25113948

Markou, Giorgos; Vandamme, Dries; Muylaert, Koenraad

2014-11-15

368

Cyanobacterial emergence at 2.8 gya and greenhouse feedbacks.  

PubMed

Apparent cyanobacterial emergence at about 2.8 Gya coincides with the negative excursion in the organic carbon isotope record, which is the first strong evidence for the presence of atmospheric methane. The existence of weathering feedbacks in the carbonate-silicate cycle suggests that atmospheric and oceanic CO2 concentrations would have been high prior to the presence of a methane greenhouse (and thus the ocean would have had high bicarbonate concentrations). With the onset of a methane greenhouse, carbon dioxide concentrations would decrease. Bicarbonate has been proposed as the preferred reductant that preceded water for oxygenic photosynthesis in a bacterial photosynthetic precursor to cyanobacteria; with the drop of carbon dioxide level, Archean cyanobacteria emerged using water as a reductant instead of bicarbonate (Dismukes et al., 2001). Our thermodynamic calculations, with regard to this scenario, give at least a tenfold drop in aqueous CO2 levels with the onset of a methane-dominated greenhouse, assuming surface temperatures of about 60 degrees C and a drop in the level of atmospheric carbon dioxide from about 1 to 0.1 bars. The buildup of atmospheric methane could have been triggered by the boost in oceanic organic productivity that arose from the emergence of pre-cyanobacterial oxygenic phototrophy at about 2.8-3.0 Gya; high temperatures may have precluded an earlier emergence. A greenhouse transition timescale on the order of 50-100 million years is consistent with results from modeling the carbonate-silicate cycle. This is an alternative hypothesis to proposals of a tectonic driver for this apparent greenhouse transition. PMID:18237259

Schwartzman, David; Caldeira, Ken; Pavlov, Alex

2008-02-01

369

Cyanobacterial Emergence at 2.8 Gya and Greenhouse Feedbacks  

NASA Astrophysics Data System (ADS)

Apparent cyanobacterial emergence at about 2.8 Gya coincides with the negative excursion in the organic carbon isotope record, which is the first strong evidence for the presence of atmospheric methane. The existence of weathering feedbacks in the carbonate-silicate cycle suggests that atmospheric and oceanic CO2 concentrations would have been high prior to the presence of a methane greenhouse (and thus the ocean would have had high bicarbonate concentrations). With the onset of a methane greenhouse, carbon dioxide concentrations would decrease. Bicarbonate has been proposed as the preferred reductant that preceded water for oxygenic photosynthesis in a bacterial photosynthetic precursor to cyanobacteria; with the drop of carbon dioxide level, Archean cyanobacteria emerged using water as a reductant instead of bicarbonate (Dismukes et al., 2001). Our thermodynamic calculations, with regard to this scenario, give at least a tenfold drop in aqueous CO2 levels with the onset of a methane-dominated greenhouse, assuming surface temperatures of about 60C and a drop in the level of atmospheric carbon dioxide from about 1 to 0.1 bars. The buildup of atmospheric methane could have been triggered by the boost in oceanic organic productivity that arose from the emergence of pre-cyanobacterial oxygenic phototrophy at about 2.83.0 Gya; high temperatures may have precluded an earlier emergence. A greenhouse transition timescale on the order of 50100 million years is consistent with results from modeling the carbonate-silicate cycle. This is an alternative hypothesis to proposals of a tectonic driver for this apparent greenhouse transition.

Schwartzman, David; Caldeira, Ken; Pavlov, Alex

2008-02-01

370

Effect of cyanobacterial exopolysaccharides on salt stress alleviation and seed germination.  

PubMed

Effectof exopolysaccharides (EPS) produced by a consortium of cyanobacteria on germination of three crops wheat, maize and rice was studied at different salt concentrations. Production of EPS was found to be stimulated by salts, which in turn had a significant Na+ removal capability from aqueous solution. Seed germination, vigor index and mobilization efficiency in all the three crops remarkably improved when cyanobacterial EPS was applied. While germination improved significantly by 13 to 30%, mobilization efficiency increased marginally by 1.03 to 1.1 times and vigor index increased by 1.15 to 2.4 times in these crops in response to EPS under non-saline conditions. Salinity had an inhibitory effect on seed germination of all the species showing 18 to 54% reduction. However, in the presence of EPS, the salt induced inhibition diminished to 13 to 18%. Inhibitory effect of salt on chlorophyll concentration, vigor index and mobilization efficiency of the seedlings was much less in these crops in the presence of EPS, indicating the latter's role in salt stress alleviation. PMID:21387925

Arora, Monu; Kaushik, A; Rani, Nisha; Kaushik, C P

2010-09-01

371

Towards clarification of the biological role of microcystins, a family of cyanobacterial toxins.  

PubMed

Microcystins constitute a serious threat to the quality of drinking water worldwide. These protein phosphatase inhibitors are formed by various cyanobacterial species, including Microcystis sp. Microcystins are produced by a complex microcystin synthetase, composed of peptide synthetases and polyketide synthases, encoded by the mcyA-J gene cluster. Recent phylogenetic analysis suggested that the microcystin synthetase predated the metazoan lineage, thus dismissing the possibility that microcystins emerged as a means of defence against grazing, and their original biological role is not clear. We show that lysis of Microcystis cells, either mechanically or because of various stress conditions, induced massive accumulation of McyB and enhanced the production of microcystins in the remaining Microcystis cells. A rise in McyB content was also observed following exposure to microcystin or the protease inhibitors micropeptin and microginin, also produced by Microcystis. The extent of the stimulation by cell extract was strongly affected by the age of the treated Microcystis culture. Older cultures, or those recently diluted from stock cultures, hardly responded to the components in the cell extract. We propose that lysis of a fraction of the Microcystis population is sensed by the rest of the cells because of the release of non-ribosomal peptides. The remaining cells respond by raising their ability to produce microcystins thereby enhancing their fitness in their ecological niche, because of their toxicity. PMID:17359268

Schatz, Daniella; Keren, Yael; Vardi, Assaf; Sukenik, Assaf; Carmeli, Shmuel; Börner, Thomas; Dittmann, Elke; Kaplan, Aaron

2007-04-01

372

Anticholinesterase poisonings in dogs from a cyanobacterial (blue-green algae) bloom dominated by Anabaena flos-aquae.  

PubMed

Cyanobacteria (blue-green algae) implicated in the deaths of 9 dogs at Richmond Lake, SD, on Aug 26, 1985, were analyzed. The dominant cyanobacterial species from the water sample was Anabaena flos-aquae. The lyophilized bloom material or the high-performance liquid chromatography purified toxin peak, when administered to mice IP, induced clinical signs of salivation, lacrimation, urinary incontinence, defecation, convulsion, fasciculation, and respiratory arrest. Further comparison of the semipurified bloom toxin with an irreversible anticholinesterase anatoxin-a(s), produced by A flos-aquae strain NRC-525-17, revealed the bloom toxin and anatoxin-a(s) had similar properties on high-performance liquid chromatography and on the inhibition of electric eel acetylcholinesterase (EC 3.1.1.7). PMID:3132068

Mahmood, N A; Carmichael, W W; Pfahler, D

1988-04-01

373

Multi proxy chemical properties of freshwater sapropel  

NASA Astrophysics Data System (ADS)

Freshwater sapropel is organic rich lake sediment firstly named "gyttja" by Hampus van Post in 1862. It is composed of organic remains such as shell detritus, plankton, chitin of insects, spores of higher plants and mineral part formed in eutrophic lake environments. The most appropriate environments for the formation of sapropel are in shallow, overgrown post-glacial lakes and valleys of big rivers in boreal zone, while thick deposits of such kind of organic sediments rarely can be found in lakes on permafrost, mountainous regions or areas with increased aridity. Organic lake sediments are divided in 3 classes according the content of organic matter and mineral part: biogenic, clastic and mixed. The value of sapropel as natural resource increases with the content of organic matter and main applications of sapropel are in agriculture, medicine, cosmetic and chemical industry. The research of sapropel in Latvia has shown that the total amount of this natural resource is close to 2 billion m3 or ~500 million tons. Sapropel has fine, dispersed structure and is plastic, but colour due to the high natural content of phosphorus usually is dark blue, later after drying it becomes light blue. Main research of the sapropel nowadays is turned to investigation of interactions among organic and mineral part of the sapropel with living organisms thus giving the inside look in processes and biological activity of the formation. From the chemical point of view sapropel contains lipids (bitumen), water-soluble substances that are readily hydrolyzed, including humic and fulvic acids, cellulose and the residual part, which does not hydrolyze. In this work we have analyzed the class of organic sapropel: peaty, cyanobacterial and green algal types, as well as siliceous sapropel, in order to determine the presence of biologically active substances, including humic substances, proteins and enzymes as well as to check free radical scavenging activity. Samples were collected from lakes which are recognized as promising for sapropel extraction and the study may benefit the use of sapropel for soil amendments, feed additives and chemical processing.

Stankevica, Karina; Rutina, Liga; Burlakovs, Juris; Klavins, Maris

2014-05-01

374

HOMOGENIZATION OF FRESHWATER FAUNAS  

Microsoft Academic Search

? Abstract Biotic homogenization,is the increased similarity of biotas over time caused by the replacement of native species with nonindigenous species, usually as a result of introductions by humans. Homogenization,is the outcome,of three interacting processes: introductions of nonnative species, extirpation of native species, and habitat alterations that facilitate these two processes. A central aspect of the homogeniza- tion process is

Frank J. Rahel

2002-01-01

375

Why freshwater organisms survived the asteroid that killed the dinosaurs  

NASA Astrophysics Data System (ADS)

Roughly 65.5 million years ago, a massive asteroid smashed into present-day Chicxulub, Mexico. The impact set fire to Earth's surface. Dust and ash darkened the sky, sending the planet into an "impact winter" that lasted months to years and caused the extinction of nonavian dinosaurs and half of ocean-dwelling species. However, life in inland freshwater ecosystems largely escaped this fate. To try to understand why freshwater organisms held on while ocean life failed, Robertson et al. surveyed relevant research to understand how the mechanisms of extinction would have operated differently in the two environments.

Schultz, Colin

2013-08-01

376

Desmids and biofilms of freshwater wetlands: development and microarchitecture.  

PubMed

Freshwater wetlands constitute important ecosystems, and their benthic, attached microbial communities, including biofilms, represent key habitats that contribute to primary productivity, nutrient cycling, and substrate stabilization. In many wetland biofilms, algae constitute significant parts of the microbial population, yet little is known about their activities in these communities. An analysis of wetland biofilms from the Adirondack region of New York (USA) was performed with special emphasis on desmids, a group of evolutionarily advanced green algae commonly found in these habitats. Desmids constituted as much as 23.7% of the total algal and cyanobacterial flora of the biofilms during the July and August study periods. These algae represented some of the first eukaryotes to colonize new substrates, and during July their numbers correlated with fluctuations in general biofilm parameters such as biofilm thickness and dry weight as well as total carbohydrate. Significant numbers of bacteria were associated with both the EPS sheaths and cell wall surfaces of the desmids. Colonization of new substrates and development of biofilms were rapid and were followed by various fluctuations in microbial community structure over the short- and long-term observations. In addition to desmids, diatoms, filamentous green algae and transient non-motile phases of flagellates represented the photosynthetic eukaryotes of these biofilms. PMID:17450460

Domozych, David S; Domozych, Catherine Rogers

2008-01-01

377

Nematodes from terrestrial and freshwater habitats in the Arctic.  

PubMed

WE PRESENT AN UPDATED LIST OF TERRESTRIAL AND FRESHWATER NEMATODES FROM ALL REGIONS OF THE ARCTIC, FOR WHICH RECORDS OF PROPERLY IDENTIFIED NEMATODE SPECIES ARE AVAILABLE: Svalbard, Jan Mayen, Iceland, Greenland, Nunavut, Northwest territories, Alaska, Lena River estuary, Taymyr and Severnaya Zemlya and Novaya Zemlya. The list includes 391 species belonging to 146 genera, 54 families and 10 orders of the phylum Nematoda. PMID:25197239

Holovachov, Oleksandr

2014-01-01

378

Nematodes from terrestrial and freshwater habitats in the Arctic  

PubMed Central

Abstract We present an updated list of terrestrial and freshwater nematodes from all regions of the Arctic, for which records of properly identified nematode species are available: Svalbard, Jan Mayen, Iceland, Greenland, Nunavut, Northwest territories, Alaska, Lena River estuary, Taymyr and Severnaya Zemlya and Novaya Zemlya. The list includes 391 species belonging to 146 genera, 54 families and 10 orders of the phylum Nematoda. PMID:25197239

2014-01-01

379

Establishing a database of radionuclide transfer parameters for freshwater wildlife.  

PubMed

Environmental assessments to evaluate potentials risks to humans and wildlife often involve modelling to predict contaminant exposure through key pathways. Such models require input of parameter values, including concentration ratios, to estimate contaminant concentrations in biota based on measurements or estimates of concentrations in environmental media, such as water. Due to the diversity of species and the range in physicochemical conditions in natural ecosystems, concentration ratios can vary by orders of magnitude, even within similar species. Therefore, to improve model input parameter values for application in aquatic systems, freshwater concentration ratios were collated or calculated from national grey literature, Russian language publications, and refereed papers. Collated data were then input into an international database that is being established by the International Atomic Energy Agency. The freshwater database enables entry of information for all radionuclides listed in ICRP (1983), in addition to the corresponding stable elements, and comprises a total of more than 16,500 concentration ratio (CRwo-water) values. Although data were available for all broad wildlife groups (with the exception of birds), data were sparse for many organism types. For example, zooplankton, crustaceans, insects and insect larvae, amphibians, and mammals, for which there were CRwo-water values for less than eight elements. Coverage was most comprehensive for fish, vascular plants, and molluscs. To our knowledge, the freshwater database that has now been established represents the most comprehensive set of CRwo-water values for freshwater species currently available for use in radiological environmental assessments. PMID:23103210

Yankovich, T; Beresford, N A; Fesenko, S; Fesenko, J; Phaneuf, M; Dagher, E; Outola, I; Andersson, P; Thiessen, K; Ryan, J; Wood, M D; Bollhöfer, A; Barnett, C L; Copplestone, D

2013-12-01

380

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). 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

381

Toxicity of cyanobacterial bloom in the eutrophic dam reservoir (Southeast Poland).  

PubMed

Cyanobacterial bloom was observed in a highly eutrophic dam reservoir, Zemborzycki, near Lublin (SE Poland) over a warm period in the year 2007. The water bloom consisted of several cyanobacterial taxa: Anabaena circinalis, Anabaena spiroides, Anabaena flos-aquae, Planktothrix agardhii, Aphanizomenon flos-aquae, Aphanizomenon gracile, and Microcystis flos-aquae. Anabaena spp., and Aphanizomenon spp., potential producers of neurotoxic anatoxin-a, quantitatively predominated in the studied bloom. High-performance liquid chromatography (HPLC) analysis of surface scum sampled during Anabaena circinalis domination revealed the presence of anatoxin-a at a high concentration (1,035.59 microg per liter of surface scum). At the same time, neither gas chromatography/mass spectrometry (GC/MS) nor microcystin enzyme-linked immunosorbent assay (ELISA) test showed the presence of other frequently found cyanotoxins, microcystins. Toxicity of cyanobacterial bloom was assessed by the crustacean acute toxicity test Daphtoxkit F pulex using Daphnia pulex, and by the chronic toxicity test Protoxkit F with a ciliate protozoan Tetrahymena thermophila. The crude extract of cyanobacterial scum showed high toxicity for Daphnia pulex, with 24-h median effective concentration (EC50) value of 90.3 microg/L of anatoxin-a, which corresponded to the cyanobacterial density in the scum of 1.01 g dry weight/L. For Tetrahymena thermophila, 24-h EC50 was lower, evaluated to be 60.48 microg/L of anatoxin-a, which corresponded to a cyanobacterial density of 0.68 g dry weight/L of the scum. On the basis of evaluated toxicity units, the cyanobacterial extract was classified at class IV toxicity, which means high toxic hazard. PMID:20821478

Sieros?awska, Anna; Rymuszka, Anna; Kalinowska, Renata; Skowro?ski, Tadeusz; Bownik, Adam; Pawlik-Skowro?ska, Barbara

2010-03-01

382

Spatial heterogeneity of cyanobacterial communities and genetic variation of microcystis populations within large, shallow eutrophic lakes (Lake Taihu and Lake Chaohu, China).  

PubMed

Cyanobacteria, specifically Microcystis, usually form massive blooms in eutrophic freshwater lakes. Cyanobacterial samples were collected from eight sites of both Lake Taihu and Lake Chaohu in late summer to determine the diversity and distribution pattern of cyanobacteria and Microcystis in large, shallow, entropic lakes with significant spatial heterogeneity and long-term Microcystis bloom. Molecular methods based on denaturing gradient gel electrophoresis and clone library analysis were used. A similar heterogeneous distribution pattern of cyanobacteria in both lakes was observed. Most parts of these two lakes with high trophic level were dominated by Microcystis. However, in the regions with low trophic levels as well as low concentrations of chlorophyll a, Synechococcus occupied a considerable percentage. Different morphospecies and genotypes dominated the bloom-forming Microcystis populations in these two lakes. Microcystis viridis and Microcystis novacekii were dominant in Lake Chaohu, whereas Microcystis flos-aquae was dominant in Lake Taihu. Only 2 of thel3 Microcystis operational taxonomic units were shared between these two lakes. Analysis of molecular variance based on 16S to 23S internal transcribed spacer sequences indicated the significAnt genetic differentiation of Microcystis between these two lakes (F(ST) = 0.19, p < 0.001). However, only 19.46% of the genetic variability was explained by the population variation between lakes, whereas most (80.54%) of the genetic variability occurred within the lakes. Phylogenetic analysis revealed no phylogeographic structure of Microcystis population in these two lakes, as illustrated by their cosmopolitan nature. Our results revealed that spatial heterogeneity within lakes has more impact on the cyanobacterial diversity than geographical isolation in a local scale. PMID:23520854

Cai, Yuanfeng; Kong, Fanxiang; Shi, Limei; Yu, Yang

2012-01-01

383

Physiological and biochemical defense reactions of Vicia faba L.-Rhizobium symbiosis face to chronic exposure to cyanobacterial bloom extract containing microcystins.  

PubMed

The presence of cyanotoxins, mainly microcystins (MCs), in surface freshwater represents a serious health risk to aquatic organisms living in the water body, as well as terrestrial animals and plants that are in contact with contaminated water. Consequently, the use of MCs contaminated water for irrigation represents a hazard for cultivated plants and could induce severe economical losses due to crops' yield reduction. The experimental approach undertaken in this work was exposing Vicia faba seedlings (inoculated with a Rhizobium strain resistant to MCs), to water supplemented with cyanobacterial crude extract containing total microcystins at a concentration of 50 and 100 ?g/L (environmental relevant concentrations of MCs dissolved in the raw irrigation water from Lalla Takerkoust Lake-Marrakesh region). After chronic MCs exposure (2 months), biological and physiological parameters (plant growth, nitrogen uptake, mineral assimilation, and oxidative defense mechanisms) were evaluated. The results obtained showed evidence that chronic exposure to cyanobacterial bloom extract containing MCs strongly affected the physiological and biological plants activities; reduction of dry matter, photosynthetic activity, nodule number, and nitrogen assimilation. At the same time, an increase of oxidative stress was observed, as deduced from a significant increase of the activities of peroxidase, catalase, polyphenoloxidase, and phenylalanine ammonia lyase in leaves, roots, and nodules of faba bean plants exposed to cyanotoxins, especially at 100 ?g/L of MCs. This experimentation constitutes a simulation of the situation related to cyanotoxins chronic exposure of seedlings-plants via the contaminated irrigation water. For this reason, once should take into consideration the possibility of contamination of agricultural crops and the quality of irrigation water should be by the way monitored for cyanotoxins biohazard. PMID:23417437

Lahrouni, Majida; Oufdou, Khalid; El Khalloufi, Fatima; Baz, Mohamed; Lafuente, Alejandro; Dary, Mohammed; Pajuelo, Eloisa; Oudra, Brahim

2013-08-01

384

The Freshwater Crab Fauna (Crustacea, Brachyura) of the Philippines: VI. A New Cavernicolous Crab from Mindanao  

Microsoft Academic Search

A new species of cavernicolous freshwater crab of the genus Sundathelphusa Bott, 1969 (Family Parathelphusidae), S. hades, is described from Mindanao in the Philippines. The new species has greatly reduced eyes, noticeably elongated ambulatory legs and lack of dark body pigmentation, all repre- senting features associated with an obligate troglodyte. The species can be differentiated from the closest congener, S.

Masatsune Takeda; Peter K. L. Ng

2001-01-01

385

The monophyletic origin of freshwater crayfish estimated from nuclear and mitochondrial DNA sequences.  

PubMed Central

Despite their widespread use as model organisms, the phylogenetic status of the around 520 species of freshwater crayfish is still in doubt. One hypothesis suggests two distinct origins of freshwater crayfish as indicated by their geographical distribution, with two centres of origin near the two present centres of diversity; one in south-eastern United States and the other in Victoria, Australia. An alternative theory proposes a single (monophyletic) origin of freshwater crayfish. Here we use over 3000 nucleotides from three different gene regions in estimating phylogenetic relationships among freshwater crayfish and related Crustacea. We show clear evidence for monophyly of freshwater crayfish and for the sister-group relationship between crayfish and clawed lobsters. Monophyly of the superfamilies Astacoidea and Parastacoidea is also supported. However, the monophyly of the family Cambaridae is questioned with the genus Cambaroides being associated with the Astacidae. PMID:11467432

Crandall, K A; Harris, D J; Fetzner, J W

2000-01-01

386

Structural dynamics of community gene expression In a freshwater cyanobacterial bloom over a day-night cycle  

E-print Network

Studies of community gene expression, or metatranscriptomics, provide a powerful approach for quantifying changes in both the taxonomic composition (structure) and activity (function) of complex microbial systems in response ...

Wang, Jia, S.M. Massachusetts Institute of Technology

2011-01-01

387

An evaluation of freshwater mussel toxicity data in the derivation of water quality guidance and standards for copper  

USGS Publications Warehouse

The state of Oklahoma has designated several areas as freshwater mussel sanctuaries in an attempt to provide freshwater mussel species a degree of protection and to facilitate their reproduction. We evaluated the protection afforded freshwater mussels by the U.S. Environmental Protection Agency (U.S. EPA) hardness-based 1996 ambient copper water quality criteria, the 2007 U.S. EPA water quality criteria based on the biotic ligand model and the 2005 state of Oklahoma copper water quality standards. Both the criterion maximum concentration and criterion continuous concentration were evaluated. Published acute and chronic copper toxicity data that met American Society for Testing and Materials guidance for test acceptability were obtained for exposures conducted with glochidia or juvenile freshwater mussels. We tabulated toxicity data for glochidia and juveniles to calculate 20 species mean acute values for freshwater mussels. Generally, freshwater mussel species mean acute values were similar to those of the more sensitive species included in the U.S. EPA water quality derivation database. When added to the database of genus mean acute values used in deriving 1996 copper water quality criteria, 14 freshwater mussel genus mean acute values included 10 of the lowest 15 genus mean acute values, with three mussel species having the lowest values. Chronic exposure and sublethal effects freshwater mussel data available for four species and acute to chronic ratios were used to evaluate the criterion continuous concentration. On the basis of the freshwater mussel toxicity data used in this assessment, the hardness-based 1996 U.S. EPA water quality criteria, the 2005 Oklahoma water quality standards, and the 2007 U.S. EPA water quality criteria based on the biotic ligand model might need to be revised to afford protection to freshwater mussels. ?? 2007 SETAC.

March, F.A.; Dwyer, F.J.; Augspurger, T.; Ingersoll, C.G.; Wang, N.; Mebane, C.A.

2007-01-01

388

Engineering a cyanobacterial cell factory for production of lactic acid.  

PubMed

Metabolic engineering of microorganisms has become a versatile tool to facilitate production of bulk chemicals, fuels, etc. Accordingly, CO(2) has been exploited via cyanobacterial metabolism as a sustainable carbon source of biofuel and bioplastic precursors. Here we extended these observations by showing that integration of an ldh gene from Bacillus subtilis (encoding an l-lactate dehydrogenase) into the genome of Synechocystis sp. strain PCC6803 leads to l-lactic acid production, a phenotype which is shown to be stable for prolonged batch culturing. Coexpression of a heterologous soluble transhydrogenase leads to an even higher lactate production rate and yield (lactic acid accumulating up to a several-millimolar concentration in the extracellular medium) than those for the single ldh mutant. The expression of a transhydrogenase alone, however, appears to be harmful to the cells, and a mutant carrying such a gene is rapidly outcompeted by a revertant(s) with a wild-type growth phenotype. Furthermore, our results indicate that the introduction of a lactate dehydrogenase rescues this phenotype by preventing the reversion. PMID:22865063

Angermayr, S Andreas; Paszota, Michal; Hellingwerf, Klaas J

2012-10-01

389

Engineering a Cyanobacterial Cell Factory for Production of Lactic Acid  

PubMed Central

Metabolic engineering of microorganisms has become a versatile tool to facilitate production of bulk chemicals, fuels, etc. Accordingly, CO2 has been exploited via cyanobacterial metabolism as a sustainable carbon source of biofuel and bioplastic precursors. Here we extended these observations by showing that integration of an ldh gene from Bacillus subtilis (encoding an l-lactate dehydrogenase) into the genome of Synechocystis sp. strain PCC6803 leads to l-lactic acid production, a phenotype which is shown to be stable for prolonged batch culturing. Coexpression of a heterologous soluble transhydrogenase leads to an even higher lactate production rate and yield (lactic acid accumulating up to a several-millimolar concentration in the extracellular medium) than those for the single ldh mutant. The expression of a transhydrogenase alone, however, appears to be harmful to the cells, and a mutant carrying such a gene is rapidly outcompeted by a revertant(s) with a wild-type growth phenotype. Furthermore, our results indicate that the introduction of a lactate dehydrogenase rescues this phenotype by preventing the reversion. PMID:22865063

Angermayr, S. Andreas; Paszota, Michal

2012-01-01

390

Anti-cyanobacterial activity of Moringa oleifera seeds  

PubMed Central

Filtrates from crushed Moringa oleifera seeds were tested for their effects on growth and Photosystem II efficiency of the common bloom-forming cyanobacterium Microcystis aeruginosa. M. aeruginosa populations exhibited good growth in controls and treatments with 4- and 8-mg crushed Moringa seeds per liter, having similar growth rates of 0.50 (±0.01) per day. In exposures of 20- to 160-mg crushed Moringa seeds L?1, growth rates were negative and on average ?0.23 (±0.05) .day?1. Presumably, in the higher doses of 20- to 160-mg crushed seeds per liter, the cyanobacteria died, which was supported by a rapid drop in the Photosystem II efficiency (?PSII), while the ?PSII was high and unaffected in 0, 4, and 8 mg L?1. High-density populations of M. aeruginosa (chlorophyll-a concentrations of ?270 µg L?1) were reduced to very low levels within 2 weeks of exposure to ?80-mg crushed seeds per liter. At the highest dosage of 160 mg L?1, the ?PSII dropped to zero rapidly and remained nil during the course of the experiment (14 days). Hence, under laboratory conditions, a complete wipeout of the bloom could be achieved. This is the first study that yielded evidence for cyanobactericidal activity of filtrate from crushed Moringa seeds, suggesting that Moringa seed extracts might have a potential as an effect-oriented measure lessening cyanobacterial nuisance. PMID:20676212

Beekman, Wendy

2009-01-01

391

Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea)  

PubMed Central

Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach. PMID:25561679

Richman, Nadia I.; Böhm, Monika; Adams, Susan B.; Alvarez, Fernando; Bergey, Elizabeth A.; Bunn, John J. S.; Burnham, Quinton; Cordeiro, Jay; Coughran, Jason; Crandall, Keith A.; Dawkins, Kathryn L.; DiStefano, Robert J.; Doran, Niall E.; Edsman, Lennart; Eversole, Arnold G.; Füreder, Leopold; Furse, James M.; Gherardi, Francesca; Hamr, Premek; Holdich, David M.; Horwitz, Pierre; Johnston, Kerrylyn; Jones, Clive M.; Jones, Julia P. G.; Jones, Robert L.; Jones, Thomas G.; Kawai, Tadashi; Lawler, Susan; López-Mejía, Marilu; Miller, Rebecca M.; Pedraza-Lara, Carlos; Reynolds, Julian D.; Richardson, Alastair M. M.; Schultz, Mark B.; Schuster, Guenter A.; Sibley, Peter J.; Souty-Grosset, Catherine; Taylor, Christopher A.; Thoma, Roger F.; Walls, Jerry; Walsh, Todd S.; Collen, Ben

2015-01-01

392

Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea).  

PubMed

Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach. PMID:25561679

Richman, Nadia I; Böhm, Monika; Adams, Susan B; Alvarez, Fernando; Bergey, Elizabeth A; Bunn, John J S; Burnham, Quinton; Cordeiro, Jay; Coughran, Jason; Crandall, Keith A; Dawkins, Kathryn L; DiStefano, Robert J; Doran, Niall E; Edsman, Lennart; Eversole, Arnold G; Füreder, Leopold; Furse, James M; Gherardi, Francesca; Hamr, Premek; Holdich, David M; Horwitz, Pierre; Johnston, Kerrylyn; Jones, Clive M; Jones, Julia P G; Jones, Robert L; Jones, Thomas G; Kawai, Tadashi; Lawler, Susan; López-Mejía, Marilu; Miller, Rebecca M; Pedraza-Lara, Carlos; Reynolds, Julian D; Richardson, Alastair M M; Schultz, Mark B; Schuster, Guenter A; Sibley, Peter J; Souty-Grosset, Catherine; Taylor, Christopher A; Thoma, Roger F; Walls, Jerry; Walsh, Todd S; Collen, Ben

2015-02-19

393

Thio arsenosugars in freshwater mussels from the Danube in Hungary.  

PubMed

In contrast to the large body of data on naturally-occurring arsenic compounds in marine organisms, relatively little is known about arsenic speciation in freshwater biota. We report an investigation using HPLC-ICPMS into the arsenic compounds in five species of freshwater mussels collected from five sites from the Danube in Hungary. Total arsenic concentrations in the mussels ranged from 3.8-12.8 mg As kg(-1). The arsenic speciation patterns were broadly similar for mussels representing each of the five species and five sites, but quite different from those reported for marine mussels. The major extractable arsenicals were two oxo arsenosugars (glycerol sugar and phosphate sugar), and their thio analogues (thio glycerol sugar and thio phosphate sugar). Arsenobetaine, usually the major arsenical in marine organisms, was not a significant compound in the freshwater mussels and was detected in only three of the 11 samples. This is the first report of thio arsenosugars in freshwater biota and suggests that these compounds may be common and widespread naturally-occurring arsenicals. PMID:15986048

Soeroes, Csilla; Goessler, Walter; Francesconi, Kevin A; Schmeisser, Ernst; Raml, Reingard; Kienzl, Norbert; Kahn, Markus; Fodor, Peter; Kuehnelt, Doris

2005-07-01

394

The Alps as barrier to dispersal in cold-adapted freshwater fishes? Phylogeographic history and taxonomic status of the bullhead in the Adriatic freshwater drainage  

Microsoft Academic Search

The freshwater faunas of the Italian peninsula are isolated from the rest of Europe by the geographic barrier of the Alps and consequently have developed many endemic forms and contain few non-endemic species. However, some ‘non-endemics’ may either represent recent invaders of the Adriatic basin or cryptic endemic species. To test these two hypotheses against each other, we studied the

Vendula Šlechtová; Jörg Bohlen; Jörg Freyhof; Henri Persat; Giovanni B. Delmastro

2004-01-01

395

40 CFR 35.1605-3 - Publicly owned freshwater lake.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Publicly owned freshwater lake. 35.1605-3 Section 35.1605-3...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public...

2011-07-01

396

40 CFR 35.1605-3 - Publicly owned freshwater lake.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Publicly owned freshwater lake. 35.1605-3 Section 35.1605-3...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public...

2013-07-01

397

40 CFR 35.1605-3 - Publicly owned freshwater lake.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Publicly owned freshwater lake. 35.1605-3 Section 35.1605-3...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public...

2014-07-01

398

40 CFR 35.1605-3 - Publicly owned freshwater lake.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Publicly owned freshwater lake. 35.1605-3 Section 35.1605-3...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public...

2010-07-01

399

40 CFR 35.1605-3 - Publicly owned freshwater lake.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Publicly owned freshwater lake. 35.1605-3 Section 35.1605-3...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public...

2012-07-01

400

Detection of the cyanobacterial toxin, microcystin-LR, using a novel recombinant antibody-based optical-planar waveguide platform.  

PubMed

Microcystins are a major group of cyanobacterial heptapeptide toxins found in freshwater and brackish environments. There is currently an urgent requirement for highly-sensitive, rapid and in-expensive detection methodologies for these toxins. A novel single chain fragment variable (scFv) fragment was generated and is the first known report of a recombinant anti-microcystin avian antibody. In a surface plasmon resonance-based immunoassay, the antibody fragment displayed cross-reactivity with seven microcystin congeners (microcystin-leucine-arginine (MC-LR) 100%, microcystin-tyrosine-arginine (MC-YR) 79.7%, microcystin-leucine-alanine (MC-LA) 74.8%, microcystin-leucine-phenylalanine (MC-LF) 67.5%, microcystin-leucine-tryptophan (MC-LW) 63.7%, microcystin-arginine-arginine (MC-RR) 60.1% and nodularin (Nod) 69.3%, % cross reactivity). Following directed molecular evolution of the parental clone the resultant affinity-enhanced antibody fragment was applied in an optimized fluorescence immunoassay on a planar waveguide detection system. This novel immuno-sensing format can detect free microcystin-LR with a functional limit of detection of 0.19ngmL(-1)and a detection range of 0.21-5.9ngmL(-1). The assay is highly reproducible (displaying percentage coefficients of variance below 8% for intra-day assays and below 11% for inter-day assays), utilizes an inexpensive cartridge system with low reagent volumes and can be completed in less than twenty minutes. PMID:25459059

Murphy, Caroline; Stack, Edwina; Krivelo, Svetlana; McPartlin, Daniel A; Byrne, Barry; Greef, Charles; Lochhead, Michael J; Husar, Greg; Devlin, Shauna; Elliott, Christopher T; O'Kennedy, Richard J

2015-05-15

401

First records of freshwater molluscs from the ecological reserve El Edén, Quintana Roo, Mexico Primeros registros de moluscos dulceacuícolas de la Reserva Ecológica El Edén, Quintana Roo, México  

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

2007-01-01

402

[Latin American malacology. Freshwater mollusks from Argentina].  

PubMed

A report and an updated list with comments on the species of freshwater molluscs of Argentina which covers an area of 2 777 815 km2 is presented. Distributions of Gastropoda and Bivalvia families, endemic, exotic, invasive as well as entities of sanitary importance are also studied and recommendations on their conservation are provided. Molluscs related to the Del Plata Basin have been thoroughly studied in comparison to others areas of the country. This fauna exhibits relatively the biggest specific richness and keeps its affinity with the fauna of other regions of the basin in areas of Paraguay and Brasil. The 4 500 records of molluscs considered in this paper arise from the study of the collections of Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires; Museo de La Plata, La Plata and Fundación "Miguel Lillo", Tucumán. These institutions keep very important collections of molluscs in southern South America. Field information has recently been obtained and localities cited by other authors are also included in the data base. Until today, 166 species have been described, 101 belonging to 10 families of Gastropoda and 65 to 7 of Bivalvia. Families with highest specific richness are Lithoglyphidae (22) and Sphaeriidae (25), respectively. The number of endemic species (those present only in Argentina) by family is: Gastropoda: Ampullariidae (1), Cochliopidae (10), Lithoglyphidae (11), Thiariidae (3), Chilinidae (11), Lymnaeidae (2) and Physidae (2?); Bivalvia: Hyriidae (1?); Etheriidae (1?) and Sphaeriidae (10). Families with a distribution that comprise almost the whole country are: the Sphaeriidae and the gastropods Cochliopidae, Chilinidae and Lymnaeidae. Families Erodonidae and Solecurtidae (Bivalvia) were registered in mixohaline environments from Buenos Aires province. Gastropod families Thiaridae and Glacidorbiidae show a very restricted distribution. The rest of the families are present mainly in the center and north of the country. Species of sanitary interest are the propagators of: schistosomiasis -Biomphalaria peregrina, B. straminea y B. tenagophila, Planorbidae-, fasciolasis -Lymnaea viatrix and L. columnella, Lymnaeidae- and dermatitis -Chilina gibbosa and C. fluminea, Chilinidae. Invasive species are: Corbicula fluminea (Corbiculidae) and Limnoperna fortunei (Mytilidae). The construction of new areas for the protection and conservation of the high risk endemic species of freshwater molluscs is a priority. It is necessary to give special attention to the species of the patagonic mountain range and of the mesopotamic area of the Del Plata Basin. PMID:18624229

Rumi, Alejandra; Gregoric, Diego E Gutiérrez; Núñez, Verónica; Darrigran, Gustavo A

2008-03-01

403

Freshwater Ecoregions of the World  

NSDL National Science Digital Library

Designed as a collaborative venture between the Nature Conservancy and the World Wildlife Fund, the Freshwater Ecoregions of the World (FEOW) site provides a dynamic visual representation of the Earth's freshwater biodiversity. Visitors to the site can find detailed information about 426 different freshwater systems from China to Chile. First-time users can click on the map of the world on the homepage, or they can also click on the "Highlights" area. Visitors with defined interests can also use the "Find an Ecoregion" section to perform a detailed search across the entire database of regions, and they can also browse by country, major habitat type, and major rivers. It's easy to see how this site would be a terrific resource for ecology students in high school or college.

404

Ultrastructure, molecular phylogenetics, and chlorophyll a content of novel cyanobacterial symbionts in temperate sponges.  

PubMed

Marine sponges often harbor photosynthetic symbionts that may enhance host metabolism and ecological success, yet little is known about the factors that structure the diversity, specificity, and nature of these relationships. Here, we characterized the cyanobacterial symbionts in two congeneric and sympatric host sponges that exhibit distinct habitat preferences correlated with irradiance: Ircinia fasciculata (higher irradiance) and Ircinia variabilis (lower irradiance). Symbiont composition was similar among hosts and dominated by the sponge-specific cyanobacterium Synechococcus spongiarum. Phylogenetic analyses of 16S-23S rRNA internal transcribed spacer (ITS) gene sequences revealed that Mediterranean Ircinia spp. host a specific, novel symbiont clade ("M") within the S. spongiarum species complex. A second, rare cyanobacterium related to the ascidian symbiont Synechocystis trididemni was observed in low abundance in I. fasciculata and likewise corresponded to a new symbiont clade. Symbiont communities in I. fasciculata exhibited nearly twice the chlorophyll a concentrations of I. variabilis. Further, S. spongiarum clade M symbionts in I. fasciculata exhibited dense intracellular aggregations of glycogen granules, a storage product of photosynthetic carbon assimilation rarely observed in I. variabilis symbionts. In both host sponges, S. spongiarum cells were observed interacting with host archeocytes, although the lower photosynthetic activity of Cyanobacteria in I. variabilis suggests less symbiont-derived nutritional benefit. The observed differences in clade M symbionts among sponge hosts suggest that ambient irradiance conditions dictate symbiont photosynthetic activity and consequently may mediate the nature of host-symbiont relationships. In addition, the plasticity exhibited by clade M symbionts may be an adaptive attribute that allows for flexibility in host-symbiont interactions across the seasonal fluctuations in light and temperature characteristic of temperate environments. PMID:22526400

Erwin, Patrick M; López-Legentil, Susanna; Turon, Xavier

2012-10-01

405

Cyanobacterial metallochaperone inhibits deleterious side reactions of copper  

PubMed Central

Copper metallochaperones supply copper to cupro-proteins through copper-mediated protein-protein-interactions and it has been hypothesized that metallochaperones thereby inhibit copper from causing damage en route. Evidence is presented in support of this latter role for