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1

Purification and characterization of C-Phycocyanin from cyanobacterial species of marine and freshwater habitat  

Microsoft Academic Search

The present paper describes an efficient single step chromatographic method for purification of C-Phycocyanin from three cyanobacterial species, i.e., Spirulina sp. (freshwater), Phormidium sp. (marine water) and Lyngbya sp. (marine water). C-Phycocyanin from these cyanobacterial species was purified to homogeneity and some of their properties were investigated. The purification involves a multistep treatment of the crude extract by fractional precipitation

Anamika Patel; Sandhya Mishra; Richa Pawar; P. K. Ghosh

2005-01-01

2

Competitive exclusion of Cyanobacterial species in the Great Salt Lake  

Microsoft Academic Search

The Great Salt Lake is separated into different salinity regimes by rail and vehicular causeways. Cyanobacterial distributions\\u000a map salinity, with Aphanothece halophytica proliferating in the highly saline northern arm (27% saline), while Nodularia spumigena occurs in the less saline south (6–10%). We sought to test if cyanobacterial species abundant in the north are competitively\\u000a excluded from the south, and if

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

2009-01-01

3

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

4

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

PubMed Central

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 diverse marine and freshwater cyanobacterial cultures. Using degenerate PCR and the sequencing of cloned products, we show that NRPSs and PKSs are common among the cyanobacteria tested. Our molecular data, when combined with genomic searches of finished and progressing cyanobacterial genomes, demonstrate that not all cyanobacteria contain NRPS and PKS genes and that the filamentous and heterocystous cyanobacteria are the richest sources of these genes and the most likely sources of novel natural products within the phylum. In addition to validating the use of degenerate primers for the identification of PKS and NRPS genes in cyanobacteria, this study also defines numerous gene fragments that will be useful as probes for future studies of the synthesis of natural products in cyanobacteria. Phylogenetic analyses of the cyanobacterial NRPS and PKS fragments sequenced in this study, as well as those from the cyanobacterial genome projects, demonstrate that there is remarkable diversity and likely novelty of these genes within the cyanobacteria. These results underscore the potential variety of novel products being produced by these ubiquitous organisms.

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

2005-01-01

5

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

PubMed

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

Xu, Huacheng; Jiang, Helong

2013-11-01

6

Accumulation and depuration of cyanobacterial paralytic shellfish toxins by the freshwater mussel Anodonta cygnea  

Microsoft Academic Search

The increasing frequency by which the production of paralytic shellfish toxins (PST) by freshwater bloom-forming cyanobacteria is being noticed world-wide raises the possibility of PST bioaccumulation by freshwater mussels. This study evaluates PST accumulation and depuration by the freshwater mussel Anodonta cygnea exposed over a 14-day period to high densities (mean=1.4×109cellsl?1, S.D.=0.29×109cellsl?1) of the toxic cyanobacterium Aphanizomenon issatschenkoi (corresponding to

Paulo Pereira; Elsa Dias; Susana Franca; Elisa Pereira; Manuela Carolino; Vitor Vasconcelos

2004-01-01

7

An overview of the interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB): advancing the scientific understanding of freshwater harmful algal blooms.  

PubMed

There is growing evidence that the spatial and temporal incidence of harmful algal blooms is increasing, posing potential risks to human health and ecosystem sustainability. Currently there are no US Federal guidelines, Water Quality Criteria and Standards, or regulations concerning the management of harmful algal blooms. Algal blooms in freshwater are predominantly cyanobacteria, some of which produce highly potent cyanotoxins. The US Congress mandated a Scientific Assessment of Freshwater Harmful Algal Blooms in the 2004 reauthorization of the Harmful Algal Blooms and Hypoxia Research and Control Act. To further the scientific understanding of freshwater harmful algal blooms, the US Environmental Protection Agency (EPA) established an interagency committee to organize the Interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB). A theoretical framework to define scientific issues and a systems approach to implement the assessment and management of cyanobacterial harmful algal blooms were developed as organizing themes for the symposium. Seven major topic areas and 23 subtopics were addressed in Workgroups and platform sessions during the symposium. The primary charge given to platform presenters was to describe the state of the science in the subtopic areas, whereas the Workgroups were charged with identifying research that could be accomplished in the short- and long-term to reduce scientific uncertainties. The proceedings of the symposium, published in this monograph, are intended to inform policy determinations and the mandated Scientific Assessment by describing the scientific knowledge and areas of uncertainty concerning freshwater harmful algal blooms. PMID:18461763

Hudnell, H Kenneth; Dortch, Quay; Zenick, Harold

2008-01-01

8

Blooms Producing Cyanobacterial Species from Lake: A Serious Global Issue  

Microsoft Academic Search

Based on most of the literature, this paper reviewed the progress made in following aspects: cognition to cyanobacteria recruitment, various traps for studying cyanobacteria recruitment in lakes, recruitment patterns of some species of cyanobacteria and the driving factors for recruitment. Additionally, perspective studies of cyanobacteria recruitment in lakes were pointed out. In light of the existing knowledge, cyanobacteria recruitment could

Sandeep Mehra; Jaishree Dubey; Dola Bhowmik; Sanjay Dubey

9

Freshwater fish diversity in Algeria with emphasis on alien species  

Microsoft Academic Search

Little is known about freshwater fish diversity in Algeria, especially after the broad national program of introduction of\\u000a exotic species applied for over 20 years. This paper is an attempt to describe the current situation emphasizing the characteristics\\u000a of the various introductions of non-autochthonous species, their current status and their possible impacts. The freshwater\\u000a fish fauna of Algeria is composed of

Hichem M. Kara

10

Physiological studies of native cyanobacterial species Lyngbya contorta and Phormidium foveolarum in sewage waste water.  

PubMed

A variety of Cyanobacterial species predominantly ensheathed forms occurs in sewage water receiving areas. A study was conducted to analyse the potential of using native Lyngbya contorta and Phormidium foveolarum isolated from sewage water irrigated soils, for biomass production under sewage waste water. The native Cyanobacterial strains were characterised and changes in their biochemical composition in response to different concentrations of sewage waste water were investigated. Results showed that biomass(3.5-6.6 mg 10 ml?¹, 2.6-5.6 mg 10 ml?¹) and photosynthetic pigment contents increased with incubation time (chlorophyll 1.21-3.09 µg ml?¹, 1.92-9.51 µg ml?¹; carotenoid 20.8-34.8 µg ml?¹, 16.4-32.8 µg ml?¹) and decreased thereafter as nutrients became limiting. On the other hand, soluble proteins, after showing a decline, recovered faster with maximum concentration (42.6-63.3 µg ml?¹ and 59-79.8 µg ml?¹) recorded on day 8. Total carbohydrate content also increased (19.27-31.45 µg ml?¹, 14.1-28.21 µg ml?¹) in response to various concentrations of sewage waste water. The overall response was better for 50% sewage waste water concentration which showed that these native strains were suitable candidates for cultivation after proper dilution. PMID:24813018

Rana, Lalita; Chhikara, Sunil; Dhankhar, Rajesh

2014-05-01

11

Radurization of commercial freshwater fish species  

NASA Astrophysics Data System (ADS)

The effect of radurization on the shelf life of fresh Whitefish obtained through ordinary commercial channels has been determined. Whitefish fillets irradiated at 1.2 kGy and stored at 3°C have a shelf life three times longer than the unirradiated fish. When the fish was irradiated at 0.82 kGy a two fold shelf-life extension was obtained. The shelf life was estimated by sensory, chemical and microbiological evaluations. Sensory evaluation involved organoleptic assessment of raw and cooked samples. Since freshwater fish do not contain trimethylamine oxide (TMAO), alternate tests for freshness were required. It was found the determination of hypoxanthine and total volatile acid number (VAN) are excellent tests for freshness and quality of freshwater fish; thus, these analyses were adopted. The degree of radiation-induced lipid oxidation was measured by the thiobarbituric acid test (TBA). It was found at doses of 0.82 and 1.2 kGy the TBA number remained within acceptable limits in all samples. Microbiological analyses consisted of the total microbial load assessment in the sample, as well as Pseudomonas and total psychrotrophic counts. The estimated shelf lives as determined by the three separate evaluations were in very good agreement.

Chuaqui-Offermanns, N.; McDougall, T. E.; Sprung, W.; Sullivan, V.

12

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

PubMed

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

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

2013-12-01

13

The cyanobacterial CCM as a source of genes for improving photosynthetic CO2 fixation in crop species.  

PubMed

Crop yields need to nearly double over the next 35 years to keep pace with projected population growth. Improving photosynthesis, via a range of genetic engineering strategies, has been identified as a promising target for crop improvement with regard to increased photosynthetic yield and better water-use efficiency (WUE). One approach is based on integrating components of the highly efficient CO(2)-concentrating mechanism (CCM) present in cyanobacteria (blue-green algae) into the chloroplasts of key C(3) crop plants, particularly wheat and rice. Four progressive phases towards engineering components of the cyanobacterial CCM into C(3) species can be envisaged. The first phase (1a), and simplest, is to consider the transplantation of cyanobacterial bicarbonate transporters to C(3) chloroplasts, by host genomic expression and chloroplast targeting, to raise CO(2) levels in the chloroplast and provide a significant improvement in photosynthetic performance. Mathematical modelling indicates that improvements in photosynthesis as high as 28% could be achieved by introducing both of the single-gene, cyanobacterial bicarbonate transporters, known as BicA and SbtA, into C(3) plant chloroplasts. Part of the first phase (1b) includes the more challenging integration of a functional cyanobacterial carboxysome into the chloroplast by chloroplast genome transformation. The later three phases would be progressively more elaborate, taking longer to engineer other functional components of the cyanobacterial CCM into the chloroplast, and targeting photosynthetic and WUE efficiencies typical of C(4) photosynthesis. These later stages would include the addition of NDH-1-type CO(2) pumps and suppression of carbonic anhydrase and C(3) Rubisco in the chloroplast stroma. We include a score card for assessing the success of physiological modifications gained in phase 1a. PMID:23028015

Price, G Dean; Pengelly, Jasper J L; Forster, Britta; Du, Jiahui; Whitney, Spencer M; von Caemmerer, Susanne; Badger, Murray R; Howitt, Susan M; Evans, John R

2013-01-01

14

Identification of 'extinct' freshwater mussel species using DNA barcoding.  

PubMed

Freshwater mollusks are highly imperiled, with 70% of the North American species extinct, endangered, or at risk of extinction. Impoundments and other human impacts on the Coosa River of Alabama, Georgia and Tennessee of the southeastern USA alone are believed to have caused 50 mollusk species extinctions, but uncertainty over boundaries among several putatively closely related species makes this number preliminary. Our examination of freshwater mussels collected during an extensive survey of the upper-drainage basin, DNA barcoding and molecular phylogenetic analyses confirm the rediscovery of four morphospecies in the genus Pleurobema (Unionidae) previously thought to be extinct from the upper Coosa basin. A fifth 'extinct' form was found in an adjoining basin. Molecular data show that the Coosa morphologies represent at least three species-level taxa: Pleurobema decisum, P. hanleyianum and P. stabile. Endemism is higher than currently recognized, both at the species level and for multispecies clades. Prompt conservation efforts may preserve some of these taxa and their ecosystem. PMID:21585879

Campbell, David C; Johnson, Paul D; Williams, James D; Rindsberg, Andrew K; Serb, Jeanne M; Small, Kory K; Lydeard, Charles

2008-07-01

15

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

PubMed Central

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

McGrath, Justin M.; Long, Stephen P.

2014-01-01

16

Temperature-related changes in polar cyanobacterial mat diversity and toxin production  

NASA Astrophysics Data System (ADS)

One of the fastest rates of recent climate warming has been reported for the Arctic and the maritime Antarctic; for example, mean annual temperatures increased by 0.5°C per decade over the Antarctic Peninsula during the past 50 years. Owing to their comparatively simple and highly sensitive food webs, polar freshwater systems, with cyanobacterial mats representing the dominant benthic primary producers, seem well suited for monitoring environmental perturbation, including climate change. Prolonged climate change may challenge the resilience, plasticity and adaptability and thus affect the community composition of cyanobacterial mats. We demonstrate that exposing polar mat samples to raised temperatures for six months results in a change in species predominance. Mats exposed to a constant temperature of 8°C or 16°C showed high cyanobacterial diversity, commensurate with an increased presence of cyanobacterial toxins. In contrast, mats held at 4°C and 23°C seemed low in diversity. Our data thus indicate that a temperature shift to 8-16°C, potentially reached during summer months in polar regions at the present warming rate, could affect cyanobacterial diversity, and in some instances result in a shift to toxin-producing species or to elevated toxin concentrations by pre-existing species that could profoundly alter freshwater polar ecosystems.

Kleinteich, Julia; Wood, Susanna A.; Küpper, Frithjof C.; Camacho, Antonio; Quesada, Antonio; Frickey, Tancred; Dietrich, Daniel R.

2012-05-01

17

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

PubMed

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

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

2014-01-01

18

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

19

Radically different scales of phylogeographic structuring within cryptic species of freshwater shrimp (Atyidae: Caridina)  

Microsoft Academic Search

We compared the phylogeographic structures of four cryptic species of freshwater shrimp from the Caridina indistincta complex (Atyidae) in eastern Australia using sequences of the mitochondrial gene cytochrome oxidase subunit I. We found very large differences between the species in the scales of overall geographic distribution, intraspecific divergence, and population structure. These species were characterized as either: (1) species with

Timothy J. Page; Jane M. Hughes

2007-01-01

20

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

21

Polyphasic identification of cyanobacterial isolates from Australia.  

PubMed

Reliable identification of cyanobacterial isolates has significant socio-economic implications as many bloom-forming species affect the aesthetics and safety of drinking water, through the production of taste and odour compounds or toxic metabolites. The limitations of morphological identification have promoted the application of molecular tools, and encouraged the adoption of combined (polyphasic) approaches that include both microscopy- and DNA-based analyses. In this context, the rapid expansion of available sequence data is expected to allow increasingly reliable identification of cyanobacteria, and ultimately resolve current discrepancies between the two approaches. In the present study morphological and molecular characterisations of cyanobacterial isolates (n = 39), collected from various freshwater sites in Australia, were compared. Sequences were obtained for the small ribosomal subunit RNA gene (16S rDNA) (n = 36), the DNA-dependent RNA polymerase gene (rpoC1) (n = 22), and the phycocyanin operon, with its intergenic spacer region (cpcBA-IGS) (n = 19). Phylogenetic analyses identified three cyanobacterial orders: the Chroococcales (n = 8), Oscillatoriales (n = 6), and Nostocales (n = 25). Interestingly, multiple novel genotypes were identified, with 22% of the strains (17/77) having <95% similarity to available sequences in GenBank. Morphological and molecular data were in agreement at the species level for only 26% of the isolates obtained (10/39), while agreement at the genus level was obtained for 31% (12/39). Confident identification of the remaining 44% of the strains (17/39) beyond the order level was not possible. The present study demonstrates that, despite the taxonomic revisions, and advances in molecular-, and bioinformatics-tools, the lack of reliable morphological features, culture-induced pleomorphism, and proportion of misidentified or poorly described sequences in GenBank, still represent significant factors, impeding the confident identification of cyanobacteria species. PMID:24810741

Lee, Elvina; Ryan, Una M; Monis, Paul; McGregor, Glenn B; Bath, Andrew; Gordon, Cameron; Paparini, Andrea

2014-08-01

22

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

23

Filtration rate capacities in 6 species of European freshwater bivalves  

Microsoft Academic Search

Filtration rate capacities in undisturbed freshwater bivalves were determined by means of two different methods (indirect “clearance” and “suction” methods) in Anodonta anatina (L.), Unio tumidus Philipsson, Unio pictorum (L.), Unio crassus Philipsson, Dreissena polymorpha (Pallas) and Sphaerium corneum (L.). In A. anatina, D. polymorpha, and S. corneum the filtration rate (FR, 1 h-1) at 19–20°C as a function of

Jakob Kryger; Hans Ulrik Riisgård

1988-01-01

24

Cyanobacterial blooms and water quality in Greek waterbodies  

Microsoft Academic Search

The cyanobacterial species composition of nine Greek waterbodies of different type and trophic status was examined during the warm period of the year (May–October). Cyanobacterial water blooms were observed in all waterbodies. Forty-six cyanobacterial taxa were identified, 11 of which are known to be toxic. Eighteen species are reported for the first time in these waterbodies, 8 of which are

Elizabeth Vardaka; Maria Moustaka-Gouni; Catherine M. Cook; Tom Lanaras

2005-01-01

25

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

PubMed Central

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

Gloer, Peter; Pesic, Vladimir

2012-01-01

26

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

Microsoft Academic Search

BackgroundMolecular genetic analyses of parentage provide insights into mating systems. Although there are 22,000 members in Malacostraca, not much has been known about mating systems in Malacostraca. The freshwater shrimp Caridina ensifera blue, is a new species belonging to Malacostraca which was discovered recently in Sulawesi, Indonesia. Due to its small body size and low fecundity, this species is an

Gen Hua Yue; Alex Chang; Trine Bilde

2010-01-01

27

Phytoplankton sterol contents vary with temperature, phosphorus and silicate supply: a study on three freshwater species  

Microsoft Academic Search

The understanding of environmentally induced changes in the biochemical composition of phytoplankton species is of great importance in both physiological studies and ecological food web research. In extensive laboratory experiments we tested the influence of two different temperatures (10°C and 25°C) and a phosphorus supply gradient on the sterol concentrations of the three freshwater phytoplankton species Scenedesmus quadricauda, Cryptomonas ovata

Maike Piepho; Dominik Martin-Creuzburg; Alexander Wacker

2012-01-01

28

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

National Technical Information Service (NTIS)

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

A. J. Seidenberg S. C. Kendeigh

1970-01-01

29

Freshwater ascomycetes: new and noteworthy species from aquatic habitats in Florida.  

PubMed

As part of a distributional study of freshwater ascomycetes in Florida, a number of new taxa were encountered. The new taxa include six Sordariomycetes, Aniptodera megaloascocarpa sp. nov., Flammispora pulchra sp. nov., Hanliniomyces hyaloapicalis gen. et sp. nov., Lockerbia striata sp. nov., Phomatospora triseptata sp. nov. and Physalospora limnetica sp. nov., and three Dothideomycetes, Caryospora obclavata sp. nov., Lepidopterella tangerina sp. nov. and Ophiobolus shoemakeri sp. nov. These taxa are described and illustrated. Six additional species are reported from Florida for the first time; among them, two species are new reports from freshwater habitats. PMID:18751554

Raja, Huzefa A; Shearer, Carol A

2008-01-01

30

Molecular characterization of cyanobacterial diversity and yearly fluctuations of Microcystin loads in a suburban Mediterranean Lake (Lake Pamvotis, Greece).  

PubMed

Cyanobacterial blooms are a frequent phenomenon in eutrophic freshwaters worldwide, and are considered as potential hazards to ecosystems and human health, while it has been shown that on average 60% of these cyanobacterial blooms are toxic. Hepatotoxic blooms are more common than neurotoxic ones and microcystins have been found to be the most prevalent cyanobacterial hepatotoxins. Lake Pamvotis is an ancient (having been in continual existence throughout the Plio-Pleistocene period) suburban Mediterranean Lake used for recreation, fishing and irrigation purposes which has suffered eutrophication for the last three decades. We investigated cyanobacterial species composition and microcystin loads in this lake over a 16-month period. The highest microcystin concentrations were recorded in autumn, one to two months after the midsummer severe bloom. With the exception of the winter months, microcystin concentrations exceed the WHO upper limits for drinking water but not for recreational waters. Seasonal changes of microcystin bioaccumulation in edible species were also investigated. Microcystin concentrations never exceed the WHO upper limits in those species with the exception of bivalves. For a detailed characterization of the cyanobacterial species composition of the lake, we used polymerase chain reaction (PCR) amplification of the internal transcribed spacer (ITS) between 16S and 23S rRNA genes, in combination with denaturing gradient gel electrophoresis (DGGE). ITS sequences from Lake Pamvotis revealed that the cyanobacterial community of this lake is made of two major populations. A population well defined both microscopically and molecularly as Microcystis sp. dominated during autumn, and another population of filamentous cyanobacteria microscopically characterized as Anabaena sp./Aphanizomenon sp. dominated during midsummer blooms. Sequences of filamentous cyanobacteria from Lake Pamvotis revealed that this cyanobacterial population is homogeneous, although divergent from other populations worldwide. Finally, by using a combination of general and genus specific primer sets against the mcyE gene, we identified Microcystis as the only genus responsible for microcystin production in Lake Pamvotis. PMID:19657535

Vareli, Katerina; Pilidis, George; Mavrogiorgou, Maria-Christina; Briasoulis, Evangelos; Sainis, Ioannis

2009-08-01

31

Predictive Value of Species Sensitivity Distributions for Effects of Herbicides in Freshwater Ecosystems  

Microsoft Academic Search

In this article we present a review of the laboratory and field toxicity of herbicides to aquatic ecosystems. Single-species acute toxicity data and (micro)mesocosm data were collated for nine herbicides. These data were used to investigate the importance of test species selection in constructing species sensitivity distributions (SSDs), and in estimating hazardous concentrations (i.e., HC5) protective for freshwater aquatic ecosystems.

Paul J. Van den Brink; Naomi Blake; Theo C. M. Brock; Lorraine Maltby

2006-01-01

32

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...

33

Copper and zinc in four freshwater fish species from Lake Pamvotis (Greece)  

Microsoft Academic Search

Lake ecosystems are vulnerable to heavy-metal pollution. Fish samples are considered as one of the most indicative factors, in freshwater systems, for the estimation of trace metals pollution potential. Lake Pamvotis (NW Greece) is a typical Mediterranean ecosystem of great importance in regard to biodiversity and to aesthetic value. The fish species found most commonly in the lake are Cyprinus

I. Papagiannis; I. Kagalou; J. Leonardos; D. Petridis; V. Kalfakakou

2004-01-01

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

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 (EC50) at a range of total phosphate (TP) concentrations in OECD medium. The EC50 values of As(III), As(V) and DMA were 27±10, 1.15±0.04 and 19±3mg L(-1) for Chlorella sp. CE-35; 0.57±0.16, 2.3±0.2 and 56±15mgL(-1) for L. disperma, and 1.58±0.05, 1.72±0.01 and 5.9±0.1mgL(-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

36

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

PubMed Central

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

Zeng, Jin; Bian, Yuanqi; Xing, Peng

2012-01-01

37

Phylogenetic study of nine species of freshwater monogeneans using secondary structure and motif prediction from India.  

PubMed

The present study was performed to identify and validate monogenean species from different piscine hosts using molecular tools. Nine species of freshwater monogeneans were collected from gills and skin of freshwater fishes at Hastinapur, Meerut, India. After microscopic examination, molecular analysis was performed utilizing 28S gene marker. Phylogenetic analysis indicated the validation and systematic position of these nine different monogeneans belongs to the Dactylogyridae and Gyrodactylidae families. The findings also confirm that the 28S rDNA sequence is highly conserved and may prove to be useful in taxonomic studies of parasitic platyhelminthes. Besides this, the study is also supplemented by molecular morphometrics that is based on 28S secondary structure homologies of nine monogenean species. The data indicate that 28S motifs i.e., ? 50bp in size can also be considered a promising tool for monogenean species identification and their validation. PMID:23144541

Chaudhary, Anshu; Singh, Hridaya Shanker

2012-01-01

38

Photosynthesis-irradiance relationships for three species of submersed macrophytes in the tidal freshwater Hudson River  

Microsoft Academic Search

Net photosynthesis under a range of natural light intensities was determined for three common macrophytes of the tidal freshwater\\u000a Hudson River:Vallisneria americana Michx.,Potamogeton perfoliatus L., andMyriophyllum spicatum L. Light-saturated net photosynthetic rates did not differ among species, nor were there differences among species in the\\u000a light intensity at which respiration balanced photosynthesis. The initial slope (?) of the photosynthesis-irradiance (P-I)

Michael T. Harley; Stuart Findlay

1994-01-01

39

Effects of pyridaphenthion on growth of five freshwater species of phytoplankton. A laboratory study  

Microsoft Academic Search

The acute toxicity of the insecticide and acaricide pyridaphenthion to five species of freshwater phytoplankton, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris, Chlorella saccharophila and Pseudanabaena galeata was determined. Insecticide concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 2.2 to 30.9 mg\\/l. The two species of Chlorella and the cyanobacteria P. galeata were more tolerant than the

Consuelo Sabater; José M. Carrasco

2001-01-01

40

Correlations between species richness and exposure: Freshwater molluscs and macrophytes  

Microsoft Academic Search

I measured the correlation between a major environmental gradient in Inner Long Point Bay, Lake Erie, and the species richness of macrophyte and mollusc communities. This gradient of wind and current induced exposure in the benthic habitat was negatively correlated with macrophyte species richness (r = -0.68, p < 0.001), positively correlated with richness of the fingernail clam guild (r

Robert C. Bailey

1988-01-01

41

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

42

Effects of pyridaphenthion on growth of five freshwater species of phytoplankton. A laboratory study.  

PubMed

The acute toxicity of the insecticide and acaricide pyridaphenthion to five species of freshwater phytoplankton, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris, Chlorella saccharophila and Pseudanabaena galeata was determined. Insecticide concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 2.2 to 30.9 mg/l. The two species of Chlorella and the cyanobacteria P. galeata were more tolerant than the two species of Scenedesmus. Concentrations of pyridaphenthion detected in some natural waters were less than the toxic threshold for these species. PMID:11534908

Sabater, C; Carrasco, J M

2001-09-01

43

New species and new records of freshwater ascomycetes from Brazil and Costa Rica.  

PubMed

During independent surveys for freshwater ascomycetes in Brazil and Costa Rica, two new species, Torrentispora pilosa and Vertexicola ascoliberatus, and nine previously described species were recovered. Among the described species, Annulatascus biatriisporus, Anthostomella aquatica, Tamsiniella labiosa and Torrentispora crassiparietis are reported for the first time from the western hemisphere, Aniptodera chesapeakensis, Chaetosphaeria lignomollis and Jahnula seychellensis are new records for South America and Annulatascus velatisporus and Ophioceras venezuelensis are reported for the first time for Brazil. The description of the genus Torrentispora is emended to accommodate T. pilosa. The new species are described and illustrated and a brief description is provided for all new records. PMID:23080025

Barbosa, Flavia R; Gusmão, Luis F P; Raja, Huzefa A; Shearer, Carol A

2013-01-01

44

Identification of Aeromonas species isolated from freshwater fish with the microplate hybridization method.  

PubMed

Aeromonas isolates were obtained from the intestinal tracts of six species of cultured freshwater fish and identified on the basis of their genotypic and phenotypic characters. The microplate hybridization method could differentiate type strains of Aeromonas species and related bacteria. DNA-DNA hybridization analysis showed that 65 aeromonad isolates were 72 to 100% related with either Aeromonas caviae, Aeromonas hydrophila, Aeromonas jandaei, Aeromonas sobria, or Aeromonas veronii. As many as 48% of the genotypically identified A. caviae, A. hydrophila, and A. sobria isolates differed from the type strains of corresponding species in one to three phenotypic characters. These results strongly suggest that not all aeromonad isolates from freshwater fish could be identified correctly on the basis of only the phenotypic characters, indicating the usefulness of the microplate hybridization method for the identification of aeromonads. PMID:16349363

Sugita, H; Nakamura, T; Tanaka, K; Deguchi, Y

1994-08-01

45

Monitoring approaches for a toxic cyanobacterial bloom.  

PubMed

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

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

2013-08-20

46

Comparative Toxicities of Fungicide and Herbicide Formulations on Freshwater and Marine Species  

Microsoft Academic Search

The estimation of the toxic effects of plant protection products on non-target aquatic organisms is essential for risk assessment\\u000a evaluation. In this study the acute toxicity of two fungicide and two herbicide formulations was determined in four marine\\u000a species in comparison with the toxicity assessed for the freshwater crustacean Daphnia magna. From the study it is indicated that the marine

K. Kyriakopoulou; P. Anastasiadou; K. Machera

2009-01-01

47

Effect of Glyphosate on Growth of Four Freshwater Species of Phytoplankton: A Microplate Bioassay  

Microsoft Academic Search

The acute toxicity of glyphosate herbicide was tested on the four species of freshwater phytoplankton, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila. Herbicide concentrations eliciting a 50% growth reduction over 72 h (EC50) ranged from 24.5 to 41.7 mg L?1, whilst a 10% growth inhibition is achieved by herbicide concentrations ranging from 1.6 to 3.0 mg L?1, difficult to find neither in paddy

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

2009-01-01

48

Effects of bensulfuron-methyl and cinosulfuron on growth of four freshwater species of phytoplankton  

Microsoft Academic Search

The acute toxicity of sulfonylurea herbicides bensulfuron-methyl and cinosulfuron was tested on the five species of freshwater phytoplankton: Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila. Herbicide concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 8 to 104 mg\\/l for cinosulfuron and from 0.015 to 6.2 mg\\/l for bensulfuron-methyl. The pesticides bensulfuron-methyl, atrazine and benthiocarb

C. Sabater; A. Cuesta; R. Carrasco

2002-01-01

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.

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

2011-01-01

50

SIMULTANEOUS MULTIPLE SPECIES TESTING: ACUTE TOXICITY OF 13 CHEMICALS TO 12 DIVERSE FRESHWATER AMPHIBIAN, FISH, AND INVERTEBRATE FAMILIES  

EPA Science Inventory

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

51

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

National Technical Information Service (NTIS)

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

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

1987-01-01

52

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

53

Comparative toxicities of fungicide and herbicide formulations on freshwater and marine species.  

PubMed

The estimation of the toxic effects of plant protection products on non-target aquatic organisms is essential for risk assessment evaluation. In this study the acute toxicity of two fungicide and two herbicide formulations was determined in four marine species in comparison with the toxicity assessed for the freshwater crustacean Daphnia magna. From the study it is indicated that the marine crustacean species are effectively protected when acute toxicity data on Daphnia magna are used as surrogate for risk assessment while the comparative sensitivity of the unicellular green algae may vary considerably, depending on the mode of action of the specific formulation. PMID:19048176

Kyriakopoulou, K; Anastasiadou, P; Machera, K

2009-03-01

54

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

PubMed

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

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

2011-02-01

55

Toxicity of acid aluminium-rich water to seven freshwater fish species: a comparative laboratory study.  

PubMed

The present study focuses on the relative sensitivity among freshwater fish species to aqueous aluminium. Seven common Scandinavian fish species were exposed to acidic Al-rich water, acidic Al-poor water, and approximately neutral water as a control. The relative sensitivity among the species to an acute aluminium challenge was documented, and was in the following order: Atlantic salmon, Salmo salar, as the most sensitive; then roach, Rutilus rutilus; minnow, Phoxinus phoxinus; perch, Perca fluviatilis; grayling, Thymallus thymallus; brown trout, Salmo trutta; and Arctic char, Salvelinus alpinus. Substantial mortality was observed in all species when exposed to the Al-rich medium. Some mortality was also observed in minnow, roach, and brown trout exposed to the acidic Al-poor medium and the control medium. A high resistance to aluminium was observed in Arctic char, while perch was found to be more sensitive to aluminium than expected and, for the first time, a toxic response to aqueous aluminium in grayling was documented. Through controlled experimental studies, the results confirm that aluminium is an important factor in the toxicity of acidified waters to freshwater fish species. PMID:15093412

Poléo, A B; ØStbye, K; Øxnevad, S A; Andersen, R A; Heibo, E; Vøllestad, L A

1997-01-01

56

Toxins produced in cyanobacterial water blooms - toxicity and risks  

PubMed Central

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

Blaha, Ludek; Babica, Pavel; Marsalek, Blahoslav

2009-01-01

57

Reproductive impairment of a viviparous fish species inhabiting a freshwater system with anthropogenic impact.  

PubMed

The potential threat to animal reproduction by contaminated freshwater systems posed the necessity to identify and develop bioindicators and biomarkers to be used for screening and evaluation of the effects in organisms. The main goal of this work was to determine, through histological analyses and changes in gonopodium morphology, whether a freshwater system polluted by anthropogenic activities-sewage, agricultural, and industrial-could cause alterations at the organ level. We also propose the live-bearing fish, Jenynsia multidentata, as a species suitable to study the effects of contaminated aquatic environments. We compared male fish sampled at two different stations in Suquía River basin (Córdoba, Argentina), both differing in degree of pollution, through liver and testis histology and gonopodial morphometric parameters. The water quality, based on the physicochemical characteristics of the studied stations, varied markedly with a decrease in water quality at the downstream site (station 2). At the highest polluted area, detrimental effects on liver and testis were evidenced on histological analysis. Male individuals from station 2 also presented noticeable structural changes of the anal fin, such as a straight gonopodium and abnormal tip area. The present results demonstrate that a freshwater system polluted by the impacts of anthropogenic activities has detrimental effects to J. multidentata. The alterations registered in individuals from the polluted station indicate an impairment of male reproductive performance and imply a risk for other live-bearing species as well as the entire biodiversity. We consider J. multidentata a sentinel species that is useful to evaluate the potential risk present in the studied basin not only to itself but to other species as well. PMID:23124166

Hued, Andrea Cecilia; Nostro, Fabiana Laura Lo; Wunderlin, Daniel Alberto; Bistoni, María de Los Ángeles

2013-02-01

58

Effects of the organophosphorus insecticide fenitrothion on growth in five freshwater species of phytoplankton.  

PubMed

The acute toxicity of the insecticide fenitrothion was measured using four freshwater algae (Chlorella saccharophila, Chlorella vulgaris, Scenedesmus acutus, and Scenedesmus subspicatus) and one cyanobacteria (Pseudanabaena galeata). Insecticide concentrations eliciting 50% growth reduction over 96 hr (EC50) ranged from 0.84 to 11.9 mg/L. Fenitrothion was more toxic than other pesticides studied with the same algal species such as chlorsulfuron, molinate, and pyridaphenthion. The transformation of effective concentrations of fenitrothion and other pesticides obtained from toxicity measurements into percent of the saturation level in water is used as a first evaluation of potential hazard to aquatic systems. The insecticides fenitrothion and pyridaphenthion were less hazardous than the herbicides atrazine, benthiocarb, cinosulfuron, chlorsulfuron, methyl-bensulfuron, and molinate. The two species of Chlorella and the cyanobacterium Pseudanabaena were more tolerant to fenitrothion than the two species of Scenedesmus. PMID:11501280

Sabater, C; Carrasco, J M

2001-01-01

59

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

PubMed

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

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

2009-05-01

60

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

PubMed

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

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

2013-01-01

61

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

Microsoft Academic Search

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

MICHAEL M. GANGLOFF; JAMES D. WILLIAMS; JACK W. FEMINELLA

62

Host fishes and reproductive biolo K y of 6 freshwater mussel species from the Mobi e Basin, USA  

Microsoft Academic Search

Host fishes were identified for 6 species of freshwater mussels (Unionidae) from the Black Warrior River drainage, Mobile Basin, USA: Stropkitus subwxus, Pleurohemafurvum, Ptyckobran- thus greeni, Lampsilis yrrovnlis, Medionidus arutissimus, and Villosa nebulosn. Hosts were determined as those that produced juvenile mussels from glochidial infestations in the laboratory. The following mussel-fish-host relationships were established: Stropkitus subwxus with 10 species including

WENDELL R. H AAG; MELVIN L. W ARREN

63

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 (LB ) s(-1) ] and prolonged (maximum 15·4?cm?s(-1) , 15·6 LB s(-1) ) swimming speeds and B. bidyanus larvae the lowest critical (minimum 0·1?cm?s(-1) , 0·3 LB s(-1) ) and prolonged swimming speeds (minimum 1·1?cm?s(-1) , 1·0 LB 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

64

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

65

Molecular approaches for monitoring potentially toxic marine and freshwater phytoplankton species.  

PubMed

Harmful phytoplankton species are a growing problem in freshwater and marine ecosystems, because of their ability to synthesize toxins that threaten both animal and human health. The monitoring of these microorganisms has so far been based on conventional methods, mainly involving the microscopic counting and identification of cells, and using analytical and bioanalytical methods to identify and quantify the toxins. However, the increasing number of microbial sequences in the GeneBank database and the development of new tools in the last 15 years nowadays enables the use of molecular methods for detection and quantification of harmful phytoplankton species and their toxins. These methods provide species-level identification of the microorganisms of interest, and their early detection in the environment by PCR techniques. Moreover, real time PCR can be used to quantify the cells of interest, and in some cases to evaluate the proportion of toxin-producing and non-toxin-producing genotypes in a population. Recently, microarray technologies have also been used to achieve simultaneous detection and semi-quantification of harmful species in environmental samples. These methods look very promising, but so far their use remains limited to research. The need for validation for routine use and the cost of these methods still hamper their use in monitoring programs. PMID:20333361

Humbert, J F; Quiblier, C; Gugger, M

2010-07-01

66

Effects of bensulfuron-methyl and cinosulfuron on growth of four freshwater species of phytoplankton.  

PubMed

The acute toxicity of sulfonylurea herbicides bensulfuron-methyl and cinosulfuron was tested on the five species of freshwater phytoplankton: Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila. Herbicide concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 8 to 104 mg/l for cinosulfuron and from 0.015 to 6.2 mg/l for bensulfuron-methyl. The pesticides bensulfuron-methyl, atrazine and benthiocarb were more toxic than cinosulfuron, chlorsulfuron, molinate, fenitrothion and pyridaphenthion in a toxicity study with the same algal species. The transformation of effective concentrations of bensulfuron-methyl and cinosulfuron and other pesticides, obtained from toxicity measurements, into percent of the saturation level in water is used as a first evaluation of potential hazard to aquatic systems. The herbicides cinosulfuron, methyl-bensulfuron, atrazine and chlorsulfuron were more dangerous than the herbicides benthiocarb and molinate and than the insecticides fenitrothion and pyridaphenthion, in a study of hazard evaluation. The two species of Chlorella were more tolerant to both herbicides than the two species of Scenedesmus. A potential environmental hazard of sulfonylurea herbicides to aquatic systems has to be expected even at low environmental concentrations. PMID:11999778

Sabater, C; Cuesta, A; Carrasco, R

2002-02-01

67

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

PubMed Central

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

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

2004-01-01

68

Dinitrogenase reductase (Fe-protein) of nitrogenase in the cyanobacterial symbionts of three Azolla species: Localization and sequence of appearance during heterocyst differentiation.  

PubMed

Transmission electron microscopy and immunocytological labeling were used to study the distribution and ontological occurrence of dinitrogenase reductase (Fe-protein) of nitrogenase in cyanobacterial symbionts within young leaves of the water-ferns Azolla filiculoides Lamarck, A. caroliniana Willdenow, and A. pinnata R. Brown. Rabbit anti-dinitrogenase reductase antisera and goat anti-rabbit-immunoglobulin G antibody conjugated to colloidal gold were used as probes. Western blot analyses showed that a polypeptide of approx. 36 kDa (kdalton) was recognized in the symbionts of all three Azolla species and that the polyclonal sera used were monospecific. In all symbionts, nitrogenase was immunologically recognizable within heterocysts. It was absent from vegetative cells, and also from the akinetes of the A. caroliniana and A. pinnata symbionts. The differentiation of vegetative cells into heterocysts in all three symbionts was initiated by formation of additional external cell-wall layers and narrowing of the neck followed by loss of glycogen, mild vesiculation of thylakoid membranes, and the appearance of polar nodules. No nitrogenase was detected at these early stages, but it appeared in the intermediate proheterocyst stage concomitantly with the formation of contorted membranes, and reached the strongest labeling in mature heterocysts, containing extensive tightly packed membranes. Nitrogenase was evenly distributed throughout heterocysts except at the polar regions, which contained honey-comb configurations and large polar nodules. With increased age of the A. caroliniana and A. pinnata symbionts, heterocysts became highly vesiculated, with a concomitant decrease in the amount of nitrogenase detected. PMID:24220860

Braun-Howland, E B; Lindblad, P; Nierzwicki-Bauer, S A; Bergman, B

1988-12-01

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

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

PubMed Central

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

Yue, Gen Hua; Chang, Alex

2010-01-01

71

Copper and zinc in four freshwater fish species from Lake Pamvotis (Greece).  

PubMed

Lake ecosystems are vulnerable to heavy-metal pollution. Fish samples are considered as one of the most indicative factors, in freshwater systems, for the estimation of trace metals pollution potential. Lake Pamvotis (NW Greece) is a typical Mediterranean ecosystem of great importance in regard to biodiversity and to aesthetic value. The fish species found most commonly in the lake are Cyprinus carpio, Silurus aristotelis, Rutilus ylikiensis, and Carassius gibelio. The aim of the present study is to evaluate the level of contamination of two essential heavy metals (copper and zinc) appearing at high concentrations in lake water in the above four fish species. Metal concentrations were measured by atomic absorption spectroscopy in three different tissues (muscle, liver, gonads) in order to assess the fish contamination. A two-factor analysis of variance, based on the procedure of general linear models, was employed in which fish species (four levels) and fish tissue (three levels) were examined for potential influence on Cu and Zn concentrations. Differences between level means per factor were treated using Tukey's multiple comparisons of means. The study showed that C. carpio and R. ylikiensis presented the highest metal content. Tissues analysis revealed that liver and gonads accumulated the highest levels of Cu and Zn. Metal concentration in the edible part of the examined fish (muscle) were in the safety-permissible levels for human consumption. PMID:14987866

Papagiannis, I; Kagalou, I; Leonardos, J; Petridis, D; Kalfakakou, V

2004-05-01

72

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

73

Effects of malathion and carbendazim on Amazonian freshwater organisms: comparison of tropical and temperate species sensitivity distributions  

Microsoft Academic Search

The risk assessment of pesticides for freshwater ecosystems in the Amazon has relied on the use of toxicity data and water\\u000a quality criteria derived for temperate regions due to a lack of ecotoxicological studies performed with indigenous species.\\u000a This leaves an unknown margin of uncertainty for the protection of Amazonian ecosystems, as differences in environmental conditions\\u000a and species sensitivity are

Andreu RicoAndrea; Andrea V. Waichman; Rachel Geber-Corrêa; Paul J. van den Brink

2011-01-01

74

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

75

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

76

Two new species of Myxobolus (Myxozoa: Myxosporea: Bivalvulida) infecting Indian freshwater fishes in Punjab Wetlands (India).  

PubMed

A survey of parasites of freshwater fishes in Harike and Ropar Wetlands of Punjab (India) revealed the presence of two new myxosporean species belonging to the genus Myxobolus Butschli 1882. Spores of the first species, M. duodenalis sp. nov. parasitize the inner wall of the duodenum of Wallago attu (Bloch and Schneider) (Cypriniformis: Cyprinidae) vern. mulli are characterized by a broad, pyriform shape with a blunt anterior end and measures 9.0 × 3.20 ?m. Spore valves are thin, smooth, and symmetrical with no parietal folds. There are two polar capsules, prominently unequal and pyriform in shape, with a narrow anterior end and a rounded posterior end. The larger polar capsule measures 4.70 × 1.76 ?m and the smaller 2.76 × 1.06 ?m. The larger polar capsule occupies more than half, while the smaller one occupies one third of the spore body cavity. An intercapsular process is absent. Spores of the second species, Myxobolus patialensis sp. nov. parasitize the caudal fin of Labeo rohita (Ham. 1822) (Cypriniformis: Cyprinidae) vern. rohu are pyriform in valvular view, measuring 11.28 × 6.67 ?m. The two shell valves are asymmetrical and contain five parietal folds along the posterior end of the spore. Two anteriorly situated polar capsules, elongated and oval in shape are prominently unequal in size. The larger polar capsule measures 4.8 × 3.1 ?m and smaller one 1.70 × 1.51 ?m. The larger polar capsule lies obliquely to the spore axis and the smaller one is at the same level but pointing outward anteriolaterally. An intercapsular process is absent. This species is characterized by having a prominent ridge on the shell surface anteriolaterally on the side of the smaller polar capsule. PMID:21394535

Kaur, Harpreet; Singh, Ranjeet

2011-05-01

77

Cyanobacterial signature genes  

Microsoft Academic Search

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

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

2003-01-01

78

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

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

Coaggregation by the freshwater bacterium Sphingomonas natatoria alters dual-species biofilm formation.  

PubMed

Coaggregation is hypothesized to enhance freshwater biofilm development. To investigate this hypothesis, the ability of the coaggregating bacterium Sphingomonas natatoria to form single- and dual-species biofilms was studied and compared to that of a naturally occurring spontaneous coaggregation-deficient variant. Attachment assays using metabolically inactive cells were performed using epifluorescence and confocal laser scanning microscopy. Under static and flowing conditions, coaggregating S. natatoria 2.1gfp cells adhered to glass surfaces to form diaphanous single-species biofilms. When glass surfaces were precoated with coaggregation partner Micrococcus luteus 2.13 cells, S. natatoria 2.1gfp cells formed densely packed dual-species biofilms. The addition of 80 mM galactosamine, which reverses coaggregation, mildly reduced adhesion to glass but inhibited the interaction and attachment to glass-surface-attached M. luteus 2.13 cells. As opposed to wild-type coaggregating cells, coaggregation-deficient S. natatoria 2.1COGgfp variant cells were retarded in colonizing glass and did not interact with glass-surface-attached M. luteus 2.13 cells. To determine if coaggregation enhances biofilm growth and expansion, viable coaggregating S. natatoria 2.1gfp cells or the coaggregation-deficient variant S. natatoria 2.1COGgfp cells were coinoculated in flow cells with viable M. luteus 2.13 cells and allowed to grow together for 96 h. Coaggregating S. natatoria 2.1gfp cells outcompeted M. luteus 2.13 cells, and 96-h biofilms were composed predominantly of S. natatoria 2.1gfp cells. Conversely, when coaggregation-deficient S. natatoria 2.1COGgfp cells were coinoculated with M. luteus 2.13 cells, the 96-h biofilm contained few coaggregation-deficient S. natatoria 2.1 cells. Thus, coaggregation promotes biofilm integration by facilitating attachment to partner species and likely contributes to the expansion of coaggregating S. natatoria 2.1 populations in dual-species biofilms through competitive interactions. PMID:19376917

Min, K R; Rickard, A H

2009-06-01

81

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

NASA Astrophysics Data System (ADS)

This work is devoted to characterization of zinc interaction in aqueous solution with two marine planktonic ( Thalassiosira weissflogii = TW, Skeletonema costatum = SC) and two freshwater periphytic species ( Achnanthidium minutissimum = AMIN, Navicula minima = NMIN) by combining adsorption and electrophoretic measurements with surface complexation modeling and by assessing Zn isotopes fractionation during both long term uptake and short term adsorption on diatom cells and their frustules. Reversible adsorption experiments were performed at 25 and 5 °C as a function of exposure time (5 min to 140 h), pH (2 to 10), zinc concentration in solution (10 nM to 1 mM), ionic strength ( I = 0.001 to 1.0 M) and the presence of light. While the shape of pH-dependent adsorption edge is almost the same for all four species, the constant-pH adsorption isotherm and maximal Zn binding capacities differ by an order of magnitude. The extent of adsorption increases with temperature from 5 to 25 °C and does not depend on light intensity. Zinc adsorption decreases with increase of ionic strength suggesting competition with sodium for surface sites. Cell number-normalized concentrations of sorbed zinc on whole cells and their silica frustules demonstrated only weak contribution of the latter (10-20%) to overall zinc binding by diatom cell wall. Measurements of electrophoretic mobilities ( ?) revealed negative diatoms surface potential in the full range of zinc concentrations investigated (0.15-760 ?mol/L), however, the absolute value of ? decreases at [Zn] > 15 ?mol/L suggesting a change in surface speciation. These observations allowed us to construct a surface complexation model for Zn binding by diatom surfaces that postulates the constant capacitance of the electric double layer and considers Zn complexation with carboxylate and silanol groups. Thermodynamic and structural parameters of this model are based on previous acid-base titration and spectroscopic results and allow quantitative reproduction of all adsorption experiments. Although Zn adsorption constants on carboxylate groups are almost the same, Zn surface adsorption capacities are very different among diatom species which is related to the systematic differences in their cell wall composition and thickness. Measurements of Zn isotopic composition ( 66Zn/( 64Zn)) performed using a multicollector ICP MS demonstrated that irreversible incorporation of Zn in cultured diatom cells produces enrichment in heavy isotope compared to growth media (? 66Zn(solid-solution) = 0.27 ± 0.05, 0.08 ± 0.05, 0.21 ± 0.05, and 0.19 ± 0.05‰ for TW, SC, NMIN, and AMIN species, respectively). Accordingly, an enrichment of cells in heavy isotopes (? 66Zn(solid-solution) = 0.43 ± 0.1 and 0.27 ± 0.1‰ for NMIN and AMIN, respectively) is observed following short-term Zn sorption on freshwater cells in nutrient media at pH ˜ 7.8. Finally, diatoms frustules are enriched in heavy isotopes compared to solution during Zn adsorption on silica shells at pH ˜ 5.5 (? 66Zn(solid-solution) = 0.35 ± 0.10‰). Measured isotopes fractionation can be related to the structure and stability of Zn complexes formed and they provide a firm basis for using Zn isotopes for biogeochemical tracing.

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

2006-02-01

82

Freshwater ascomycetes: Wicklowia aquatica , a new genus and species in the Pleosporales from Florida and Costa Rica  

Microsoft Academic Search

During a latitudinal survey of freshwater ascomycetes, an unidentified fungus with bitunicate asci was found on submerged\\u000a wood and herbaceous material from Florida and Costa Rica. Based on morphological characteristics and 28S rDNA large subunit\\u000a (LSU) sequence data, this fungus is described as a new genus and species, Wicklowia aquatica, and placed in the Pleosporales (Pleosporomycetidae, Dothideomycetes). Phylogenetic analyses based

Huzefa A. Raja; Astrid Ferrer; Carol A. Shearer; Andrew N. Miller

2010-01-01

83

First evidence of cryptic species diversity and significant population structure in a widespread freshwater nematode morphospecies (Tobrilus gracilis).  

PubMed

Free-living nematodes are ubiquitous and highly abundant in terrestrial and aquatic environments, where they sustain ecosystem functioning by mineralization processes and nutrient cycling. Nevertheless, very little is known about their true diversity and intraspecific population structure. Recent molecular studies on marine nematodes indicated cryptic diversity and strong genetic differentiation of distinct populations, but for freshwater nematode species, analogous studies are lacking. Here, we present the first extensive molecular study exploring cryptic species diversity and genetic population structure of a widespread freshwater nematode morphospecies, Tobrilus gracilis, from nine postglacially formed European lakes. Taxonomic species status of individuals, analysed for fragments of the mitochondrial COI gene and for the large (LSU) and small (SSU) ribosomal subunits, were determined by morphological characteristics. Mitochondrial and nuclear markers strongly supported the existence of three distinct genetic lineages (Tg I-III) within Tobrilus gracilis, suggesting that this morphospecies indeed represents a complex of highly differentiated biological species. High genetic diversity was also observed at the population level. Across the nine lakes, 19 mitochondrial, and seven (LSU) and four (SSU) nuclear haplotypes were determined. A phylogeographical analysis revealed remarkable genetic differentiation even among neighbouring lake populations for one cryptic lineage. Priority and persistent founder effects are possible explanations for the observed population structure in the postglacially colonized lakes, but ask for future studies providing direct estimates of freshwater nematode dispersal rates. Our study suggests therefore that overall diversity of limnetic nematodes has been so far drastically underestimated and challenges the assumed ubiquitous distribution of other, single freshwater nematode morphospecies. PMID:23927432

Ristau, Kai; Steinfartz, Sebastian; Traunspurger, Walter

2013-09-01

84

Composition and energy density of eggs from two species of freshwater turtle with twofold ranges in egg size  

Microsoft Academic Search

Lipid, protein, ash, carbohydrate and water content and energy density of eggs were measured from different clutches over a range of egg size in two species of freshwater turtle. Dry egg contents consisted of protein (54–60%), lipid (25–31%) and ash (5–6%) while carbohydrate was found to be negligible (<1%). Albumen consisted principally of water (?98%), and the dry component was

David T. Booth

2003-01-01

85

Diversity of Freshwater Thioploca Species and Their Specific Association with Filamentous Bacteria of the Phylum Chloroflexi  

Microsoft Academic Search

Phylogenetic diversity among filamentous sulfur-oxidizing bacteria of the genus Thioploca inhabiting freshwater\\/brackish environments was analyzed in detail. The 16S rRNA gene sequence of Thioploca found in a freshwater lake in Japan, Lake Okotanpe, was identical to that of Thioploca from Lake Ogawara, a brackish lake. The samples of the two lakes could be differentiated by the sequences of their 23S

Fumiko Nemoto; Hisaya Kojima; Manabu Fukui

86

Determination of mercury in some freshwater fish species from Chahrmahal va Bakhtyari Province, Iran and potential limits for human consumption.  

PubMed

Concentrations of mercury in four freshwater fish species from Gandoman and Sooleghan Lagoons and Beheshtabad River were determined by cold vapor atomic absorption spectrometry. Concentrations of mercury in muscle of 90 fish ranged from 21 to 31 ?g kg(-1) (mean = 26 ?g kg(-1)). Statistical analysis showed no statistical relationship between mean mercury concentration and fish species, although concentration of mercury in different seasons and habitats was statistically different (p < 0.05). The results indicated that fish from Gandoman and Sooleghan Lagoons and Beheshtabad River have concentrations well below the maximum permissible levels of mercury according to international standards with no health risk for consumers. PMID:24084980

Raissy, Mehdi

2013-12-01

87

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

88

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

PubMed Central

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

Kojima, Hisaya; Teske, Andreas; Fukui, Manabu

2003-01-01

89

Dinitrogenase reductase (Fe-protein) of nitrogenase in the cyanobacterial symbionts of three Azolla species: Localization and sequence of appearance during heterocyst differentiation  

Microsoft Academic Search

Transmission electron microscopy and immunocytological labeling were used to study the distribution and ontological occurrence of dinitrogenase reductase (Fe-protein) of nitrogenase in cyanobacterial symbionts within young leaves of the water-ferns Azolla filiculoides Lamarck, A. caroliniana Willdenow, and A. pinnata R. Brown. Rabbit anti-dinitrogenase reductase antisera and goat anti-rabbit-immunoglobulin G antibody conjugated to colloidal gold were used as probes. Western blot

Ellen B. Braun-Howland; Peter Lindblad; Sandra A. Nierzwicki-Bauer; Birgitta Bergman

1988-01-01

90

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

91

Selenium:mercury molar ratios in freshwater fish from Tennessee: individual, species, and geographical variations have implications for management.  

PubMed

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

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

2012-06-01

92

The trace element analysis in freshwater fish species, water and sediment in Iyidere stream (Rize-Turkey).  

PubMed

Many environmental problems like dam construction, agricultural debris, flooding and industrial establishments threaten Iyidere stream (Rize, Turkey) on the southeastern coast of the Black Sea (Turkey). The trace element concentrations in water, fish and sediments in lyidere stream (Rize, Turkey) were investigated in this study. The concentration of six different elements in ten freshwater fish species and sediment was determined using energy dispersive X-ray fluorescence method. A radioisotope excited X-ray fluorescence analysis using the method of multiple standard addition is applied for the elemental analysis of fish and sediments. Water samples for trace metals were analyzed using standard spectrophotometry methods. A qualitative analysis of spectral peaks showed that ten different freshwater fish samples (Chondrostoma colchicum, Chalcalburnus chalcoides, Salmo trutta labrax, Alburnoides bipunctatus, Leuciscus cephalus, Barbus taurus escherichia, Capoeta tinca, Neogobius kessleri, Rutilus frisii, Lampetra lanceolata) and sediment contained phosphorus (P), sulphur (S), chlorine (Cl), potassium (K), calcium (Ca) and titanium (Ti). Heavy metals as toxic elements for biota (Pb, Cd, Hg, Zn and Mn etc.) were not detected in fish, water and sediments. Thus, It can be declared that freshwater fish of Iyidere does not contains health risks for consumers in terms of metal pollution. PMID:24171246

Verep, Bulent; Mutlu, Cengiz; Apaydin, Gokhan; Cevik, Ugur

2012-07-15

93

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

94

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

PubMed Central

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

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

2014-01-01

95

HABITAT USE OF TWENTY-FIVE COMMON SPECIES OF OREGON FRESHWATER FISHES  

EPA Science Inventory

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

96

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

PubMed

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

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

2013-05-01

97

Occurrence and elimination of cyanobacterial toxins in two Australian drinking water treatment plants.  

PubMed

In Australian freshwaters, Anabaena circinalis, Microcystis spp. and Cylindrospermopsis raciborskii are the dominant toxic cyanobacteria. Many of these surface waters are used as drinking water resources. Therefore, the National Health and Medical Research Council of Australia set a guideline for MC-LR toxicity equivalents of 1.3 microg/l drinking water. However, due to lack of adequate data, no guideline values for paralytic shellfish poisons (PSPs) (e.g. saxitoxins) or cylindrospermopsin (CYN) have been set. In this spot check, the concentration of microcystins (MCs), PSPs and CYN were determined by ADDA-ELISA, cPPA, HPLC-DAD and/or HPLC-MS/MS, respectively, in two water treatment plants in Queensland/Australia and compared to phytoplankton data collected by Queensland Health, Brisbane. Depending on the predominant cyanobacterial species in a bloom, concentrations of up to 8.0, 17.0 and 1.3 microg/l were found for MCs, PSPs and CYN, respectively. However, only traces (<1.0 microg/l) of these toxins were detected in final water (final product of the drinking water treatment plant) and tap water (household sample). Despite the low concentrations of toxins detected in drinking water, a further reduction of cyanobacterial toxins is recommended to guarantee public safety. PMID:15109885

Hoeger, Stefan J; Shaw, Glen; Hitzfeld, Bettina C; Dietrich, Daniel R

2004-05-01

98

The freshwater shrimps of the genera Caridina and Parisia from karst caves of Sulawesi Selatan, Indonesia, with descriptions of three new species (Crustacea: Decapoda: Caridea: Atyidae)  

Microsoft Academic Search

The present study reports on collections of hypogean freshwater atyid shrimps of the genera Caridina Milne Edwards, 1837, and Parisia Holthuis, 1956, obtained from the karst caves and associated epigean waters of Sulawesi, Indonesia. Six species of Caridina were present, of which two are new to science and one is new to Sulawesi, as well as one new species of

Y. Cai; P. K. L. Ng

2009-01-01

99

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

PubMed

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

Berry, John P; Lind, Owen

2010-05-01

100

Sperm removal and ejaculate size correlate with chelae asymmetry in a freshwater crayfish species  

Microsoft Academic Search

Asymmetry in traits of sexual relevance may impair copulation behaviour and sexual performance of males, ultimately resulting\\u000a in a fitness cost. Freshwater crayfish males use chelae, a sexually selected trait, to secure and position the female prior\\u000a to and during mating. Thus, a relatively large chelae asymmetry, resulting from accidental loss and regeneration of one cheliped\\u000a after autotomy, could have

Paolo Galeotti; Diego Rubolini; Fabio Pupin; Roberto Sacchi; Mauro Fasola

2008-01-01

101

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

PubMed

Lake Pamvotis is a shallow, eutrophic Mediterranean lake with ecological significance. This paper deals with the evaluation 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 cyanobacterial extracts containing environmentally detected concentrations of MCYST can cause reduced survival rate of fish species. The results clearly indicate that cyanobacterial blooms in Lake Pamvotis may be regarded as human and fish health hazard. Continuous monitoring of the lake is suggested, in order to prevent future possible intoxications. PMID:21713485

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

2012-05-01

102

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

103

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

104

Prodigious polyphyly in imperilled freshwater pearly-mussels (Bivalvia: Unionidae): a phylogenetic test of species and generic designations  

USGS Publications Warehouse

Unionid bivalves or freshwater pearly-mussels (Unionoidea: Unionidae) serve as an exemplary system for examining many of the problems facing systematists and conservation biologists today. Most of the species and genera were described in the late 1800s and early 1900s, but few phylogenetic studies have been conducted to test conventional views of species and classification. Pearly-mussels of Gulf Coastal drainages of the southeastern United States from the Escambia (southern Alabama to Florida) to the Suwannee Rivers (Florida) are a unique fauna comprised of approximately 100 species, with about 30 endemic to the region. In this study, mitochondrial cytochrome c oxidase subunit I and 16S rRNA gene sequences were used to test the monophyly and to estimate evolutionary relationships of five unionid species representing three different genera. The molecular phylogenies depict all three genera as polyphyletic. The prodigious polyphyly exhibited within unionids is due to incorrect notions of homology and false assumptions about missing anatomical data. In contrast, the molecular phylogeny provides evidence to support the recognition of all five unionid species as distinct evolutionary entities. Furthermore, molecular genealogical evidence supports the elevation of Quincuncina infucata (Conrad) of the Suwannee River to species level, for which Q. kleiniana (Lea) is available.

Lydeard, Charles; Minton, Russell L.; Williams, James D.

2000-01-01

105

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

106

[Freshwater macroinvertebrates from Cocos Island, Costa Rica: species and comparison with other islands of the Eastern Tropical Pacific].  

PubMed

Freshwater macroinvertebrates from Cocos Island, Costa Rica: species and comparison with other islands of the Eastern Tropical Pacific. Cocos Island is an oceanic island in the Eastern Pacific, at 496km from Cabo Blanco, Costa Rica. This 24 km2 island is surrounded by a protected marine area of 9640 km2. it was declared National Park in 1978 and a World Heritage by UNESCO in 1997. Freshwater macroinvertebrate fauna was collected in 20 sites covering three rivers (Genio, Chatam and Sucio) and two creeks (Minuto and an unnamed creek behind the park rangers' house). Tank bromeliads or phytotelmata were also examined for aquatic macroinvertebrates. Physicochemical parameters were determined in 13 study sites. Additionally, a comparison with other islands in the Eastern Tropical Pacific was conducted to determine the most important factors controlling the diversity in Tropical Pacific islands. A total of 455 individuals were collected belonging to 20 taxa (mostly identified to genus level) from 15 families of aquatic insects. Other macroinvertebrates such as Palaemonid shrimps, Hidrachnida and Oligochaeta were also collected. The family Staphylinidae (Coleoptera) was the most abundant, followed by Chironomidae (Diptera). Diptera was the order of insects with the highest taxonomic richness. A relationship between distance and the number of families was observed supporting the premises of the Theory of island Biogeography. This relationship was improved by correcting area by island elevation, indicating that mountainous islands had the richest faunas, potentially due to high cloud interception that feeds freshwater environments favoring the establishment of aquatic fauna. Physicochemical variables were similar in all sites, possibly due to the geology and the absence of significant sources of pollution on the island. PMID:23885581

Gutiérrez-Fonseca, Pablo E; Ramírez, Alonso; Umaña, Gerardo; Springer, Monika

2013-06-01

107

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

Microsoft Academic Search

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

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

1997-01-01

108

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

109

The Native Bacterioplankton Community in the Central Baltic Sea Is Influenced by Freshwater Bacterial Species? †  

PubMed Central

The Baltic Sea is one of the largest brackish environments on Earth. Despite extensive knowledge about food web interactions and pelagic ecosystem functioning, information about the bacterial community composition in the Baltic Sea is scarce. We hypothesized that due to the eutrophic low-salinity environment and the long water residence time (>5 years), the bacterioplankton community from the Baltic proper shows a native “brackish” composition influenced by both freshwater and marine phylotypes. The bacterial community composition in surface water (3-m depth) was examined at a single station throughout a full year. Denaturing gradient gel electrophoresis (DGGE) showed that the community composition changed over the year. Further, it indicated that at the four extensive samplings (16S rRNA gene clone libraries and bacterial isolates from low- and high-nutrient agar plates and seawater cultures), different bacterial assemblages associated with different environmental conditions were present. Overall, the sequencing of 26 DGGE bands, 160 clones, 209 plate isolates, and 9 dilution culture isolates showed that the bacterial assemblage in surface waters of the central Baltic Sea was dominated by Bacteroidetes but exhibited a pronounced influence of typical freshwater phylogenetic groups within Actinobacteria, Verrucomicrobia, and Betaproteobacteria and a lack of typical marine taxa. This first comprehensive analysis of bacterial community composition in the central Baltic Sea points to the existence of an autochthonous estuarine community uniquely adapted to the environmental conditions prevailing in this brackish environment.

Riemann, L.; Leitet, C.; Pommier, T.; Simu, K.; Holmfeldt, K.; Larsson, U.; Hagstrom, A.

2008-01-01

110

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, FRANÃÂOIS-MARIE GIBON, PAUL V. LOISELLE, MICHEL SARTORI, JOHN S. SPARKS, and MELANIE L. J. STIASSNY (;)

2003-11-01

111

CARIDINA TRIFASCIATA, A NEW SPECIES OF FRESHWATER SHRIMP (DECAPODA: ATYIDAE) FROM HONG KONG  

Microsoft Academic Search

A new atyid species, Caridina trifasciata, is described from Hong Kong. Morphological investigations show obvious differences from previously recorded Caridina species, and indicate that it belongs to the 'C. serrata Stimpson (1860) group' of Atyidae.

Rita S. W. Yam; Yixiong Cai

112

Primary structures of decapod crustacean metallothioneins with special emphasis on freshwater and semi-terrestrial species.  

PubMed

Cadmium injections induced only a single form of metallothionein (MT) in the midgut gland of Potamon potamios, whereas the same treatment induced two isoforms in Astacus astacus. The only difference between the two latter isoforms was that one had an extra N-terminal methionine residue. MT from P. potamios showed structural differences from other decapod crustacean MTs. It contained a Gly-Thr motif at positions 8 and 8a, which had previously been found only in certain vertebrate and molluscan MTs. Furthermore P. potamios MT contained two to three times as many glutamic acid residues as normally found in decapod crustacean MT. The primary structure of MT from the freshwater crayfish A. astacus showed a high degree of sequence identity with MT from other decapod crustaceans, especially the marine astacidean Homarus americanus, although two valine residues were unexpectedly found at positions 8 and 21, where lysine residues are normally found. PMID:8921011

Pedersen, S N; Pedersen, K L; Højrup, P; Depledge, M H; Knudsen, J

1996-11-01

113

Parasites of South African freshwater fish. II. Redescription of the African species of the genus Phyllodistomum Braun, 1899 (Trematoda: Gorgoderinae) and the description of a new species.  

PubMed

During 1980 a survey of the parasites of freshwater fish was conducted in the Sabie and Crocodile Rivers in the southern part of the Kruger National Park, Transvaal. A new species of Phyllodistomum, Braun, 1899, for which the name Phyllodistomum bavuri is proposed, was found in the urinary bladder of many of the catfish, Clarias gariepinus (Burchell, 1822), examined. The new species resembles Phyllodistomum linguale Odhner, 1902 and Phyllodistomum vanderwaali Prudhoe & Hussey, 1977, but may be differentiated from the former species in that the ovary and the vitellaria are smooth, while those of P. linguale are irregularly lobed. The ovary of P. vanderwaali is irregularly lobed while that of P. bavuri never has more than 3 indistinct lobes. In addition, P. bavuri is much larger than P. vanderwaali. P. bavuri is readily differentiated from the other 4 African species of Phyllodistomum, namely, Phyllodistomum spatula (Odhner, 1902), Phyllodistomum spatulaeforme (Odhner, 1902), Phyllodistomum ghanense Thomas, 1958 and Phyllodistomum symmetrorchis Thomas, 1958. For comparative purposes the African species are briefly redescribed and illustrated. P. bavuri occurred throughout the year and their numbers do not appear to fluctuate seasonally in the Kruger National Park. PMID:6493727

Boomker, J

1984-06-01

114

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

PubMed Central

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

Zeng, Yonghui; Kasalicky, Vojtech; Simek, Karel

2012-01-01

115

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

Microsoft Academic Search

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

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

2007-01-01

116

Molecular Systematics of the Freshwater Prawn Genus Macrobrachium Bate, 1868 (Crustacea: Decapoda: Palaemonidae) Inferred from mtDNA Sequences, with Emphasis on East Asian Species  

Microsoft Academic Search

Min-Yun Liu, Yi-Xiong Cai, and Chyng-Shyan Tzeng (2007)Molecular systematics of the freshwater prawn genus Macrobrachium Bate, 1868 (Crustacea: Decapoda: Palaemonidae) inferred from mtDNA sequences, with emphasis on East Asian species. Zoological Studies46(3): 272-289. Based on the mitochondrial DNA fragment of the large subunit (16S) ribosomal RNA gene, the monophyletic phylogeny of the genus Macrobrachium, including both land-locked and euryhaline species,

Min-Yun Liu; Yi-Xiong Cai; Chyng-Shyan Tzeng

117

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

Microsoft Academic Search

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

PABLO SABAT; ROBERTO F. NESPOLO; FRANCISCO BOZINOVIC

2004-01-01

118

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

119

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.

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

2014-01-01

120

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

EPA Science Inventory

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

121

Quantitative Estimation of Phytoplankton Species in Freshwater by Two Step Linear Regression Analysis Using Spectral Absorption Method  

NASA Astrophysics Data System (ADS)

We proposed a passive method to distinguish and to estimate density of the Cyanobacteria (Cyanophyceae) in a mixed population by measuring the spectral absorption of sample waters, based on two step linear regression analysis. Natural freshwater usually contains a few species of algae and dissolved organic carbon (DOC). In the experiment, we picked out four typical algal groups characterized by their own colors, Cyanophycaeae or blue-green alga, Chlorophyceae or green alga, and Bacillariophyceae and Dinophyceae or brown algae. In the first step, for each of the pure sample waters which contained only one of these elemental substances, dependence of spectral characteristic on its density was determined using simple linear regression analysis. Resultant spectral characteristics which we call gradient vectors were used to estimate spectral absorption of mixed sample waters containing the four elementary algae and DOC by multiple linear regression analysis. This method offers new perspectives for identification and estimation of density of blue-green algae and other unialgal species in a mixed population.

Lokuhewage, Asha Udayamali M.; Naiki, Yasuhiro; Toyooka, Satoru

122

Effects of cadmium and resource quality on freshwater detritus processing chains: a microcosm approach with two insect species.  

PubMed

Detritus processing is vital for freshwater ecosystems that depend on the leaf litter from riparian vegetation and is mediated by microorganisms and aquatic invertebrates. Shredder invertebrates transform coarse particulate organic matter into fine particulate organic matter used as food by collector species. Direct and indirect effects of contaminants can impair detritus processing and thus affect the functioning of these ecosystems. Here, we assessed the combined effects of a toxic metal (cadmium) and resource quality (leaf species) on detritus processing and shredder-collector interactions. We considered two types of leaves, alder and eucalyptus that were microbially conditioned under different Cd concentrations in the laboratory. The microbial communities present on leaves were analyzed by Denaturing Gradient Gel Electrophoresis (DGGE), and we also measured microbial respiration rates. Sericostoma vittatum (a caddisfly shredder) and Chironomus riparius (a midge collector) were also exposed to Cd and allowed to consume the corresponding alder or eucalyptus leaves. We evaluated C. riparius growth and leaf mass loss in multispecies microcosms. Cadmium exposure affected leaf conditioning and fungal diversity on both leaf species, as assessed by DGGE. Cadmium exposure also affected the mass loss of alder leaves by reductions in detritivore feeding, and impaired C. riparius growth. Chironomus riparius consumed alder leaf discs in the absence of shredders, but S. vittatum appear to promote C. riparius growth in treatments containing eucalyptus. These results show that indirect effects of contaminants along detritus-processing chains can occur through effects on shredder-collector interactions such as facilitation but they also depend on the nutritional quality of detritus and on sensitivity and feeding plasticity of detritivore species. PMID:24648031

Campos, Diana; Alves, Artur; Lemos, Marco F L; Correia, António; Soares, Amadeu M V M; Pestana, João L T

2014-07-01

123

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

PubMed

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

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

2014-09-01

124

Development and application of proxies for past cyanobacterial N? fixation  

Microsoft Academic Search

N? fixation adds bioavailable nitrogen to the global oceans and therewith drives modern-day marine primary productivity. The diazotrophs mainly responsible for the fixation of nitrogen are principally found in the cyanobacterial lineage with unicellular and filamentous non-heterocystous species dominating. There is evidence that diazotrophic cyanobacteria were of similar importance in the past nitrogen cycling, in particular during the formation of

T Bauersachs

2010-01-01

125

Insights from Cyanobacterial Genomes for the Development of Extraterrestrial Photoautotrophic Biotechnologies  

Microsoft Academic Search

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

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

2010-01-01

126

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

EPA Science Inventory

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

127

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...

128

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

129

Phospholipase A2 activity in three species of littoral freshwater rotifers exposed to several toxicants.  

PubMed

We analyzed three species of Lecane, a littoral rotifer, for susceptibility to six metals and four organic toxicants using a fluorometric assay based on inhibition of activity of the enzyme phospholipase A2. The metallic toxicants that we tested included Cd, Cr, Cu, Pb, Hg (as HgCl2), and Ti; the organic toxicants included benzene, ethyl acetate, toluene, and vinyl acetate. The three species differed greatly with respect to their susceptibility to the various toxicants. Lecane quadridentata, for example, was particularly sensitive to the four organic compounds (median effective concentration values [EC50] ranged from 6.6 x 10(-4)-0.987 mg/L). Lecane luna, in contrast, seemed particularly sensitive to metals (EC50 values ranged from 2 x 10(-6)-1.92 mg/L). Lecane hamata was relatively insensitive to organic solvents (EC50 values ranged from 4.25-126.5 mg/L). PMID:14551999

Pérez-Legaspi, Ignacio Alejandro; Rico-Martínez, Roberto

2003-10-01

130

Spring migration of some anadromous freshwater fish species in the northern Bothnian Sea  

Microsoft Academic Search

Quantitative estimations of spring migrating fish have been made in the mouth part of the small coastal river Ängerån which flows into the northern Bothnian Sea (63°35?N, 19°50?E). In 1981 nearly 3 000 fish were counted ascending to the spawning grounds in the lower reaches of the Ängerån. These species, such as pike, perch, roach and ide, adapted to the

K. Miiller; E. Berg

1982-01-01

131

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

132

Two new species of Myxobolus (Myxozoa:Myxosporea:Bivalvulida) from freshwater fishes of Punjab wetlands (India).  

PubMed

During the present study two new species were collected from mucous membrane around gill lamellae of Puntius sophore (Ham.) vern. chittal and Cirrhina mrigala (Ham.) vern. mrigal from Harike Wetland, Punjab respectively. Spore of the first species i.e. Myxobolus chittalii are histozoic, pear shaped with characteristic nipple-like anterior end and rounded posterior end. They measure 9.0 × 6.18 ?m. Polar capsules are two, equal, measuring 4.5 × 2.4 ?m, pyriform with bluntly pointed anterior end and rounded posterior end. They are placed posteriorly from the tip of the spore and are parallel to each other in the spore body cavity. A prominent, tongue shaped intercapsular process is present. Spores of the second species i.e. M. mehlhorni are histozoic, oval to egg in shape having narrow, blunt anterior end and broad rounded posterior end, measure 8.9 × 6.8 ?m. Shell valves smooth, symmetrically thin, measure 0.5 ?m in thickness. Parietal folds are absent. Polar capsules two, prominently unequal, placed anteriorly and converge towards the anterior end. Both polar capsules are flask-shaped with anterior end having a prominent neck. The larger polar capsule measure 3.7 × 2.5 ?m occupying less than half while the smaller one measure 2.6 × 1.5 ?m and occupy less than one-third of the spore body cavity. An intercapsular process is absent. PMID:22654312

Kaur, Harpreet; Singh, Ranjeet

2011-06-01

133

The identity of the Sarawak freshwater crab Parathelphusa oxygona Nobili, 1901, with description of a new species, Parathelphusa nobilii, from Western
Kalimantan, Indonesia, Borneo (Crustacea: Brachyura: Gecarcinucidae).
 

PubMed

The identity of the common lowland freshwater crab in western Sarawak, Borneo, East Malaysia, Parathelphusa oxygona Nobili, 1901 (family Gecarcinucidae), is clarified. The species is redescribed and figured, and its taxonomy discussed. Specimens from western Kalimantan, Borneo, Indonesia, which have been referred to P. oxygona are here referred to a new species, Parathelphusa nobilii. The new species can be differentiated from congeners by its relatively more swollen branchial regions of the carapace, wider and lower external orbital tooth, relatively more slender male abdomen and a straight male first gonopod.  PMID:24871403

Ng, Peter K L

2014-01-01

134

Length-weight relationships for 36 freshwater fish species from two tropical reservoirs: Ayamé I and Buyo, Côte d'Ivoire.  

PubMed

Nowadays, the successful management of small scale fisheries requires the use of biometric data collected in the field, in order to transform them into suitable indicators. The present study describes the length-weight relationships for 36 freshwater fish species from two tropical reservoirs Ayame I and Buyo, in Côte d'Ivoire. The main objective of the study was to provide a length weight key for a wide range of freshwater fish species from these tropical reservoirs exploited by the inland fisheries. The samplings were carried out at Buyo from July 1997 to August 1998, and from August 2004 to July 2005 in Ayame I. Fish specimens were collected from catches of artisanal fisheries using gill-nets, cast-nets, beach seines and bamboo traps. After landings, samples were identified, total weight for each specimen was recorded to the nearest gram and standard length was measured to the nearest millimetre. A total of 12 724 individuals belonging to 15 families and 24 genera were obtained in this study. The results indicated that the family with the highest number of species was Cichlidae with eight species. Six families were recorded with only one species per family. The value of the exponent b in the length weight relationships (W=aL(b)) ranged from 2.173 for Marcusenius furcidens to 3.472 for Polypterus endlicheri and the median of b was 2.756. The modal value of the exponent b equal to 2.70 indicates that most of the fish species in Ayame I and Buyo Reservoirs have negative allometric growth. The length weight parameters of the three species, Lates niloticus, Synodontis koensis and S. punctifer are described for the first time in these regions. The present length-weight key for 36 freshwater fish species could be used as a valuable tool for fishery managers, in order to improve the inland fisheries statistics largely based on hydropower reservoirs in Côte d'Ivoire. PMID:23342533

Tah, Leonard; Gouli; Bi, Goore; Da Costa, Kouassi Sebastino

2012-12-01

135

Immunological and molecular detection of digenetic infections in different species of Egyptian freshwater snails.  

PubMed

Due to the possibility of utilizing different snails in the combat of Schistosoma in Egypt; it is important to study the role it may play in transmitting other trematodes of medical and veterinary importance. Taking this background into consideration, polymerase chain reaction (PCR) assay was designed to identify trematode species at larval stages in intermediate hosts (cercariae in snails) using a combination of standard and molecular methods. This PCR assay was also applied to naturally infected molluscan in order to assess the use of the procedure for detection. The importance of the present study was to demonstrate the epidemiological situation and application in control. PMID:23697024

Saad, Abdel-Hakim; Varjabedian, Kohar G; Abdel-Gaber, Rewaida A; Hassan, Hany M; Abdel-Halim, Noha T

2013-04-01

136

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

PubMed Central

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

2008-01-01

137

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

PubMed Central

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

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

1997-01-01

138

Biological effect of the Planktothrix sp. FP1 cyanobacterial extract.  

PubMed

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 effects of the Planktothrix sp. FP1 cell extract on Xenopus embryos and on human Peripheral Blood Mononuclear Cells (PBMC) were investigated. FETAX (Frog Embryo Teratogenesis Assay-Xenopus) showed that the cyanobacterial extract had no teratogenic potential, though embryotoxicity was detected (LC(50) 2.944g/l wet weight). The same extract inhibited the proliferation of PBMC stimulated in vitro by phytohemagglutinin (PHA), and strongly interfered with the production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). PMID:11711123

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

2002-03-01

139

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

PubMed Central

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

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

2013-01-01

140

Lucidascocarpa pulchella, a new ascomycete genus and species from freshwater habitats in the American tropics.  

PubMed

A new fungus collected from submerged wood in Costa Rica and Ecuador has ascostromatic ascomata with fissitunicate asci and lacks pseudoparaphyses, characters that place it in the Dothideaceae (Dothideales). It is unusual in the order because it has white ascomata. Based on other morphological characters however this fungus could not be accommodated in any existing genus in the Dothideaceae and it is described herein as a new genus and species, Lucidascocarpa pulchella. These morphological features are characteristic of L. pulchella: ascomata glistening, white, each with a long, periphysate neck; a membranous peridium composed of 5-7 thin-walled, hyaline cells; pseudoparaphyses absent; asci fissitunicate, clavate, eight-spored; ascospores seven-septate, hyaline, multiguttulate, verruculose, surrounded by a large, regular, gelatinous sheath. PMID:18833757

Ferrer, Astrid; Raja, Huzefa A; Shearer, Carol A

2008-01-01

141

Trichodina colisae (Ciliophora: Trichodinidae): new parasite records for two freshwater fish species farmed in Brazil.  

PubMed

Family Trichodinidae comprises ciliate protozoa distributed worldwide; they are considered some of the main parasitological agents infecting cultivated fish. However, the trichodinidae parasitizing important fish species cultured in Brazil are unknown, and more taxonomic studies on this group of parasites are required. This research morphologically characterizes Trichodina colisae Asmat & Sultana, (2005) of pacu (Piaractus mesopotamicus) and patinga hybrid (P. mesopotamicus × P. brachypomus) cultivated in the central and southeast regions of the country. Fresh assemblies were made from mucus scraped from the skin, fins and gills, fixed with methanol and, subsequently, impregnated with silver nitrate and stained with Giemsa for assessment under light microscopy. This research reports not only the second occurrence of T. colisae in the world, but also its first occurrence in South America. PMID:23207983

Jerônimo, Gabriela Tomas; Marchiori, Natália da Costa; Pádua, Santiago Benites de; Dias Neto, José; Pilarski, Fabiana; Ishikawa, Márcia Mayumi; Martins, Maurício Laterça

2012-01-01

142

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

143

Two new genera and three new species of freshwater crabs (Crustacea: Pseudothelphusidae: Potamocarcinini) from Chiapas, Mexico.  

PubMed

Two new genera, Sylvathelphusa n. gen. and Tzotzilthelphusa n. gen., and three new species, Sylvathelphusa kalebi n. sp., S. cavernicola n. sp. and Tzotzilthelphusa villarosalensis n. sp., of the tribe Potamocarcinini, family Pseudothelphusidae, are described from Chiapas, Mexico. Sylvathelphusa n. gen. is characterized by a male gonopod with the marginal plate between the caudal and mesial surfaces abruptly widening distally and forming a triangular apical projection; and a mesial process as a strong, acute spine forming a 90º angle with respect to the principal axis of the gonopod. Tzotzilthelphusa n. gen. exhibits a male gonopod strongly bent laterally in the distal third, and a mesial surface rounded distally with acute spinules. Sylvathelphusa n. gen. is similar to Potamocarcinus in gonopod morphology, in both straight and with a mesial process developed as strong tooth in a similar shape and position. Tzotzilthelphusa n. gen. is similar to Phrygiopilus in that the gonopods of both genera develop a supra-apical process that is a continuation of the mesial surface. The new taxa come from the Los Altos de Chiapas region and bring the total number of pseudothelphusid genera in Chiapas to 11. PMID:24613999

Villalobos, José Luis; Alvarez, Fernando

2013-01-01

144

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

145

Seasonal reproductive biology of two species of freshwater catfish from the Venezuelan floodplains.  

PubMed

Oxydoras sifontesi and Pimelodus blochii are seasonal breeder fish. Spawn occurs once a year over a short interval of time, at the beginning of the rainy season. The gonadosomatic index (GSI), and plasma levels of steroid hormones of P. blochii and O. sifontesi were studied from fish samples, collected from the Portuguesa River (Portuguesa State, Venezuela) in 1998 and 2004-2005, respectively. Gonadal tissue samples were obtained and processed for histology. A macroscopic classification of the degree of gonadal maturation was performed using a six-stage maturity scale. Data was analyzed and compared as a function of the gonadal maturation stage. The GSI of both O. sifontesi and P. blochii increases from stages II to V (preparatory and prespawning periods) and decreases in the stage VI (postspawning). In males, the GSI was usually lower than in females. In both species, the higher plasmatic concentration of 17beta-estradiol (17beta-E) and testosterone (T) were obtained from specimens in stages IV or V. A significant decrease in both hormones was observed in stage VI, except for the males of P. blochii where T concentration did not change between gonadal stages IV-VI. The relevance of these results is discussed in relation to the seasonality and the particular hydrological conditions of the region. PMID:17416368

Marcano, Dayssi; Cardillo, Elizabeth; Rodriguez, Christian; Poleo, Germán; Gago, Nathalie; Guerrero, Hilda Y

2007-01-01

146

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

PubMed Central

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

Gross, Jeana; Budowski, P.

1966-01-01

147

Use of landscape pattern metrics and multiscale data in aquatic species distribution models: a case study of a freshwater mussel  

Microsoft Academic Search

The distributions of freshwater mussels are controlled by landscape factors operating at multiple spatial scales. Changes\\u000a in land use\\/land cover (LULC) have been implicated in severe population declines and range contractions of freshwater mussels\\u000a across North America. Despite widespread recognition of multiscale influences few studies have addressed these issues when\\u000a developing distribution models. Furthermore, most studies have disregarded the role

Robert L. Hopkins

2009-01-01

148

Taxonomical notes on selected freshwater fish species described from northern and central Vietnam (Cypriniformes: Balitoridae, Cobitidae, Cyprinidae, Nemacheilidae; Perciformes: Channidae, Osphronemidae; Synbranchiformes: Mastacembelidae).  

PubMed

Selected, little known taxa of northern and central Vietnamese freshwater fish species are reviewed. Nomenclatural acts are taken: Hemibarbus lehoai is placed in synonymy of H. maculatus, Paracobitis hagiangensis in synonymy of Schistura caudofurca. A neotype of Micronemacheilus bacmeensis is assigned. The name Channa hanamensis is treated as a nomen nudum. Two labeonine species described from China are nomenclaturally affected: Garra findolabium is transferred to Vinagarra and its specific epithet is treated as a noun in apposition; the specific epithet of Sinigarra napoense is corrected to napoensis. PMID:24668657

Endruweit, Marco

2014-03-18

149

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)

150

Freshwater Macroinvertebrates.  

ERIC Educational Resources Information Center

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

Nalepa, T. F.

1978-01-01

151

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

152

The effect of environmental parameters and cyanobacterial blooms on phytoplankton dynamics of a Portuguese temperate Lake  

Microsoft Academic Search

The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ability of many cyanobacteria\\u000a to produce cyanotoxins. In the present work, the eutrophied Vela Lake (Central Portugal), used for recreational purposes and\\u000a as a water source for agriculture, was monitored every fortnight between 2000 and 2001. Phytoplankton diversity and densities\\u000a were measured and correlated to

Daniela R. de Figueiredo; Ana S. S. P. Reboleira; Sara C. Antunes; Nelson Abrantes; Ulisses Azeiteiro; Fernando Gonçalves; Mário J. Pereira

2006-01-01

153

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.

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

2013-01-01

154

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

Microsoft Academic Search

The genus of filamentous cyanobacteria, Lyngbya, has been found to be a rich source of bioactive metabolites. However, identification of such compounds from Lyngbya has largely focused on a few marine representatives. Here, we report on the pharmacology and toxicology of pahayokolide A from a freshwater isolate, Lyngbya sp. strain 15-2, from the Florida Everglades. Specifically, we investigated inhibition of

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

2004-01-01

155

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.

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

2012-01-01

156

The effect of food on the acute toxicity of silver nitrate to four freshwater test species and acute-to-chronic ratios  

Microsoft Academic Search

Acute silver toxicity studies were conducted with and without food for four common freshwater test species: Daphnia magna, Ceriodaphnia dubia, Pimephales promelas (fathead minnow—FHM), and Oncorhynchus mykiss (rainbow trout—RBT) in order to generate acute-to-chronic ratios (ACR). The studies were conducted similarly (i.e., static-renewal\\u000a or flow-through) to chronic\\/early-life stage studies that were previously performed in this laboratory. The acute toxicity\\u000a (EC\\/LC50

Rami B. NaddyGina; Gina R. McNerney; Joseph W. Gorsuch; Russell A. Bell; James R. Kramer; Kuen B. Wu; Paul R. Paquin

157

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

PubMed

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

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

2014-05-01

158

Monogeneans on native and introduced freshwater fishes from Cuba with the description of a new species of Salsuginus Beverley-Burton, 1984 from Limia vittata (Poeciliidae).  

PubMed

During a parasitological survey carried out between March and September 2003 in Cuba, the following monogeneans were found on the gills of freshwater fishes: Salsuginus cubensis n. sp. on the Cuban molly Limia vittata Guichenot (Poeciliidae); Cichlidogyrus sclerosus Paperna & Thurston, 1969 and C. tilapiae Paperna, 1960 on the African cichlid Tilapia rendalli Boulenger (Cichlidae); Haplocleidus dispar Mueller, 1936 and Pterocleidus acer Mueller, 1936 (all Dactylogyridae) on the sunfish Lepomis macrochirus Rafinesque (Centrarchidae) (new geographical records); and Gyrodactylus sp. (Gyrodactylidae) on the biajaca Nandopsis tetracanthus Valenciennes (Cichlidae) (new host and geographical record). Salsuginus cubensis differs from all other species of the genus in the size and morphology of the copulatory complex. The occurrence of C. sclerosus, C. tilapiae, H. dispar and P. acer in their respective hosts is due to the introduction of these hosts to Cuba. A review of the species composition of the Monogenea in native and introduced freshwater fish from Cuba is presented and the zoogeographical distribution of the species found is briefly discussed. PMID:16786283

Mendoza-Franco, Edgar F; Vidal-Martínez, V M; Cruz-Quintana, Y; León, F L Prats

2006-07-01

159

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

PubMed

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

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

2014-01-01

160

Freshwater Initiative  

NSDL National Science Digital Library

Launched in 1998 by The Nature Conservancy (TNC), the Freshwater Initiative aims "to protect the plants and animals dependent on freshwaters and develop solutions to key causes of freshwater biodiversity decline." To achieve this goal, Freshwater Initiative staff identifies sites that harbor critical aquatic biodiversity, targets conservation activities at several key freshwater sites, and develops expert and informative collaborations to foster freshwater conservation. The homepage is straightforward; the Strategies section outlines the Initiative's fundamental goals and approaches and identifies key regions of interest (see color map). The Indicators of Hydrologic Alteration (IHA) section describes IHA software (not free) used "to statistically characterize environmental regimes" (most commonly used by hydrologists and ecologists to evaluate streamflow data). Finally, a nice selection of links rounds out the site.

2001-01-01

161

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

162

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

PubMed

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

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

2011-05-01

163

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

PubMed

A new species of the genus Dugesia is described from the Lake Ohrid region in the western part of the Balkan Peninsula, forming the first fully documented species description for this genus in the Ohrid area. The morphological species delimitation is supported by complementary molecular, karyological, and cytogenetic data available from the literature. Therefore, species delineation is based on a truly integrative approach. Further, a short account on the degree of freshwater planarian endemicity in the Ohrid region is provided. PMID:23840163

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

2013-01-01

164

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

PubMed

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

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

2013-04-01

165

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

166

A new species of Henneguya, a gill parasite of a freshwater fish Anabas testudineus (Bloch) affected with ulcerative disease syndrome from Manipur, India.  

PubMed

A new species of Henneguya parasitizing tissues affected by the ulcerative disease syndrome of a freshwater fish Anabas testudineus (Bloch) from Khiodum and Pumlen lakes of Manipur state is described. Of the fishes examined 75% were found to be infested with this myxozoan parasite. Mature spores of the new species are elongated, biconvex, and oval with bluntly rounded anterior end and gradually tapering posterior end with a caudal prolongation, measuring 12.6-15.4 (14.0+/- 1.1) microm in length. Length of the caudal prolongation is 11.2-12.6 (11.7+/- 0.6) microm. The width of the spores is 5.6-7.0 (6.3+/- 0.5) microm. The length of the polar capsules is 5.6-6.3 (5.5+/- 0.3) microm. PMID:18351559

Hemanand, Th; Meitei, N Mohilal; Bandyopadhyay, Probir K; Mitra, Amlan K

2008-01-01

167

On the appearance of cyanobacterial calcification in modern stromatolites  

NASA Astrophysics Data System (ADS)

In August 1991 calcified (magnesian calcite) filamentous cyanobacteria ( Scytonema mirabile) appeared on the surface of a modern lacustrine stromatolite (Lake R2, Rangiroa Atoll, Tuamotu Archipelago, French Polynesia). Previously, the topmost photosynthetic layer of this sediment was devoid of such microbial biomineralisers. The calcified cyanobacteria are accompanied by magnesian calcite grains which are evocative of bacterial precipitates. Although the appearance of cyanobacterial calcification might be related to environmental changes in the lake (in particular a decrease in water salinity), the persistence of non-calcified specimens of a filamentous cyanobacteria ( Phormidium crossbyanum), which was once a dominant species of the lake benthos, shows that calcification and environmental conditions might be only indirectly related. Thus, attempts to use the fossil record of calcareous cyanobacterial skeletons to infer changes in the chemical composition of past oceans cannot be made without due regard of biological processes like the appearance of new competitors.

Défarge, Christian; Trichet, Jean; Coute, Alain

1994-12-01

168

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

SciTech Connect

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

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

1994-09-01

169

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...

170

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

171

CARIDINA SPONGICOLA, NEW SPECIES, A FRESHWATER SHRIMP (CRUSTACEA: DECAPODA: ATYIDAE) FROM THE ANCIENT MALILI LAKE SYSTEM OF SULAWESI, INDONESIA  

Microsoft Academic Search

The ancient Malili lake system of Sulawesi, Indonesia, harbours an endemic species flock of atyid shrimps. Caridina spongicola, new species, is described from the outlet of Lake Towuti, the largest of the five connected lakes. The new species differs from all other Caridina species by a combination of morphological features and a unique colour pattern, and is unusual among atyid

Kristina Zitzler; Yixiong Cai

2006-01-01

172

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

PubMed

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

Brix, Kevin V; Grosell, Martin

2012-04-01

173

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.

2010-01-01

174

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

175

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

176

Selection on protein-coding genes of natural cyanobacterial populations.  

PubMed

We examined the distribution of synonymous and non-synonymous changes in 12 protein-coding genes of natural populations of cyanobacteria to infer changes in gene functionality. By comparing mutation distributions within and across species using the McDonald-Kreitman test, we found data sets to contain evidence for purifying selection (hetR of Trichodesmium, nifH of Cylindrospermopsis raceborskii and rpoC1 of Anabaena lemmermannii) and positive selection (kaiC of Microcoleus chthonoplastes and rbcX of Anabaena and Aphanizomenon sp.). Other genes from the same set of clonal isolates (petB and rbcL in M. chthonoplastes and Anabaena/Aphanizomenon, respectively) did not harbour evidence for either form of selection. The results of branch models of codon evolution agreed fully with the results of the McDonald-Kreitman test in terms of significance and absolute value of the dN/dS estimates. The high frequency of gene-specific mutation patterns and their association with branches that separate closely related cyanobacterial genera suggest that evolutionary tests are suited to uncover gene-specific selective differentiation in cyanobacterial genomes. At the same time, given the lack of information about the history of cyanobacteria, analysis of larger numbers of protein-coding genes of clonal cyanobacterial isolates will produce more detailed pictures of the effects of natural selection. PMID:16913914

Mes, Ted H M; Doeleman, Marije; Lodders, Nicole; Nübel, Ulrich; Stal, Lucas J

2006-09-01

177

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.

Agha, Ramsy; Quesada, Antonio

2014-01-01

178

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

2014-01-01

179

The effect of food on the acute toxicity of silver nitrate to four freshwater test species and acute-to-chronic ratios.  

PubMed

Acute silver toxicity studies were conducted with and without food for four common freshwater test species: Daphnia magna, Ceriodaphnia dubia, Pimephales promelas (fathead minnow-FHM), and Oncorhynchus mykiss (rainbow trout-RBT) in order to generate acute-to-chronic ratios (ACR). The studies were conducted similarly (i.e., static-renewal or flow-through) to chronic/early-life stage studies that were previously performed in this laboratory. The acute toxicity (EC/LC50 values) of silver without food ranged from 0.57 ?g dissolved Ag/l for C.dubia to 9.15 ?g dissolved Ag/l for RBT. The presence of food resulted in an increase in EC/LC50 values from 1.25× for RBT to 22.4× for C. dubia. Invertebrate food type was also shown to effect acute silver toxicity. Food did not affect EC/LC50s or ACRs as greatly in fish studies as in invertebrate studies. ACRs for both invertebrate species were <1.0 when using acute studies without food but were 1.22 and 1.33 when using acute studies with food. ACRs for FHMs ranged from 4.06 to 7.19, while RBT ACRs ranged from 28.6 to 35.8 depending on whether food was present in acute studies. The data generated from this research program should be useful in re-determining a final ACR for silver in freshwater as well as in risk assessments. PMID:21779820

Naddy, Rami B; McNerney, Gina R; Gorsuch, Joseph W; Bell, Russell A; Kramer, James R; Wu, Kuen B; Paquin, Paul R

2011-11-01

180

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.

Jersey, New; Center, Liberty S.; Coalition, New J.

2006-01-01

181

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

182

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

PubMed

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

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

2014-03-01

183

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

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

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

PubMed Central

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

Xu, Minli; Su, Zhengchang

2009-01-01

186

Freshwater shrimp genera Caridina and Parisia (Decapoda: Caridea: Atyidae) of Madagascar, with descriptions of four new species  

Microsoft Academic Search

Three new species of Caridina and one new species of Parisia from caves in northern Madagascar are described and figured. A useful key-character, the presence or absence of an apical hook on the dactylus and propodus of pereiopods 1 and\\/or 2, is re-evaluated. Revised keys are provided for both genera.

Ann R. Gurney

1984-01-01

187

Effects of propanil, tebufenozide and mefenacet on growth of four freshwater species of phytoplankton: a microplate bioassay  

Microsoft Academic Search

The Albufera Natural Park situated in Valencia (Spain), with a very rich flora and fauna is surrounded by rice fields in which pesticide spraying is a regular practice. With this in mind, the sensitivity of four algal species, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila to pesticides propanil, tebufenozide and mefenacet was studied using single species toxicity tests.

D. Gómez de Barreda Ferraz; C. Sabater; J. M. Carrasco

2004-01-01

188

Cyanobacterial Flora from Polluted Industrial Effluents  

Microsoft Academic Search

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

Amit Parikh; Vishal Shah; Datta Madamwar

2006-01-01

189

Cyanobacterial lipopolysaccharides and human health - a review  

PubMed Central

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

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

2006-01-01

190

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

PubMed Central

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

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

2008-01-01

191

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

PubMed

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

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

2007-12-01

192

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

193

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".

2010-01-01

194

The Biogeography and Phylogeny of Unicellular Cyanobacterial Symbionts in Sponges from Australia and the Mediterranean  

Microsoft Academic Search

The distribution, host associations, and phylogenetic relationships of the unicellular cyanobacterial symbionts of selected marine sponges were investigated with direct 16s rDNA sequencing. The results indicate that the symbionts of the marine sponges Aplysina aerophoba, Ircinia variabilis, and Petrosia ficiformis from the Mediterranean, four Chondrilla species from Australia and the Mediterranean, and Haliclona sp. from Australia support a diversity of

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

2004-01-01

195

The role of modern and fossil cyanobacterial borings in bioerosion and bathymetry  

Microsoft Academic Search

Measurements on modern coral reefs at Lee Stocking Island (Bahamas) illustrate that boring cyanobacteria species make a major contribution to microboring bioerosion rates. Borings attributed to cyanobacteria also occur in fossil environments. Bioerosional studies on Permian and Triassic reefs show similar intensities to those observed on modern equivalents. The importance of borings assigned to cyanobacterial activity is even more apparent

Ingrid Glaub; Klaus Vogel; Marcos Gektidis

2001-01-01

196

Cyanobacterial Protease Inhibitor Microviridin J Causes a Lethal Molting Disruption in Daphnia pulicaria  

PubMed Central

Laboratory experiments identified microviridin J as the source of a fatal molting disruption in Daphnia species organisms feeding on Microcystis cells. The molting disruption was presumably linked to the inhibitory effect of microviridin J on daphnid proteases, suggesting that hundreds of further cyanobacterial protease inhibitors must be considered potentially toxic to zooplankton.

Rohrlack, Thomas; Christoffersen, Kirsten; Kaebernick, Melanie; Neilan, Brett A.

2004-01-01

197

Effects of propanil, tebufenozide and mefenacet on growth of four freshwater species of phytoplankton: a microplate bioassay.  

PubMed

The Albufera Natural Park situated in Valencia (Spain), with a very rich flora and fauna is surrounded by rice fields in which pesticide spraying is a regular practice. With this in mind, the sensitivity of four algal species, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila to pesticides propanil, tebufenozide and mefenacet was studied using single species toxicity tests. Organisms were exposed to different concentrations of these herbicides and the algal growth was measured in a microplate reader at 410 nm, at 0, 24, 48 and 72 h. Tebufenozide appeared to be the most inhibitory to Scenedesmus and Chlorella species growth. 72 h EC50 of propanil, tebufenozide and mefenacet ranged from 0.29 to 5.98 mg/l, 0.12 to 0.15 mg/l and from 0.25 to 0.67 mg/l, respectively for the four algal species. The two species of Chlorella were more tolerant than the two species of Scenedesmus. PMID:15183992

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

2004-07-01

198

Gene copy number variation and its significance in cyanobacterial phylogeny  

PubMed Central

Background In eukaryotes, variation in gene copy numbers is often associated with deleterious effects, but may also have positive effects. For prokaryotes, studies on gene copy number variation are rare. Previous studies have suggested that high numbers of rRNA gene copies can be advantageous in environments with changing resource availability, but further association of gene copies and phenotypic traits are not documented. We used one of the morphologically most diverse prokaryotic phyla to test whether numbers of gene copies are associated with levels of cell differentiation. Results We implemented a search algorithm that identified 44 genes with highly conserved copies across 22 fully sequenced cyanobacterial taxa. For two very basal cyanobacterial species, Gloeobacter violaceus and a thermophilic Synechococcus species, distinct phylogenetic positions previously found were supported by identical protein coding gene copy numbers. Furthermore, we found that increased ribosomal gene copy numbers showed a strong correlation to cyanobacteria capable of terminal cell differentiation. Additionally, we detected extremely low variation of 16S rRNA sequence copies within the cyanobacteria. We compared our results for 16S rRNA to three other eubacterial phyla (Chroroflexi, Spirochaetes and Bacteroidetes). Based on Bayesian phylogenetic inference and the comparisons of genetic distances, we could confirm that cyanobacterial 16S rRNA paralogs and orthologs show significantly stronger conservation than found in other eubacterial phyla. Conclusions A higher number of ribosomal operons could potentially provide an advantage to terminally differentiated cyanobacteria. Furthermore, we suggest that 16S rRNA gene copies in cyanobacteria are homogenized by both concerted evolution and purifying selection. In addition, the small ribosomal subunit in cyanobacteria appears to evolve at extraordinary slow evolutionary rates, an observation that has been made previously for morphological characteristics of cyanobacteria.

2012-01-01

199

Two new species of freshwater crabs of the genus Sundathelphusa Bott, 1969 (Decapoda: Brachyura: Gecarcinucidae) from caves in Luzon, Philippines.  

PubMed

Two cave species of Sundathelphusa are described from a karst area in southern Luzon, Philippines. Both species have elongated ambulatory legs but the eyes and carapace pigmentation are well developed, indicating they are not troglobites. Sundathelphusa danae sp. nov. is superficially more similar to S. longipes (Balss, 1937) than to S. holthuisi Ng, 2010, which was described from the same locality. Sundathelphusa danae sp. nov. is distinguished from its closest congeners by its strongly convex anterolateral margin, more swollen branchial regions, possession of a complete frontal median triangle, laterally inflated subbranchial region and the more slender ambulatory legs. Sundathelphusa vienae sp. nov. is unusual among Sundathelphusa species in that its carapace is more quadrate, with the slender and almost straight male first gonopod tapered and having a pointed terminal segment.  PMID:24943634

Husana, Daniel Edison M; Yamamuro, Masumi; Ng, Peter K L

2014-01-01

200

Freshwater macroinvertebrates  

SciTech Connect

Major aspects of the biology of freshwater macroinvertebrates with emphasis on man-induced environmental changes were reviewed in this report with 183 references. The effects of both chemical and physical environmental alteration are examined. The population dynamics of the macroinvertebrates are controlled by factors such as food and feeding habits, periodicity and drift, productivity and animal-sediment interactions.(KRM)

Quigley, M.A.

1982-06-01

201

Freshwater Wetlands.  

ERIC Educational Resources Information Center

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

Naturescope, 1986

1986-01-01

202

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...

203

Comparison of the predation rate of freshwater cyclopoid copepod species on larvae of the mosquito Culex pipiens.  

PubMed

The predation rates of six copepod species: Acanthocyclops robustus G.O. Sars, Eucyclops neumani Pesta, Macrocyclops albidus Jurine, Mesocyclops longisetus Thibaud, Metacyclops grandis Kiefer and Metacyclops mendocinus Wierzejski (Copepoda: Cyclopidae) on mosquito larvae, Culex pipiens Linnaeus (Diptera: Culicidae) were assessed. Experiments consisted of 24-h incubations of one copepod and 10 larvae without extra food at 16 degrees C and 26 degrees C. Nine replicates were considered for each species and temperature. Predation rates (larvae per copepod per day) were: M. mendocinus (1.8), M. grandis (3.1), E. neumani (3.8), A. robustus (3.8), Ma. albidus (6.1) and Me. longisetus (7.0). There was a significant effect of both species and temperature on predation: all species experienced higher predation at 26 degrees C than at 16 degrees C, except for A. robustus whose predation rate was similar at both temperatures. These observations are consistent with previous results that point to Macrocyclops and Mesocyclops genera as important larval predators and suggest the need for field trials to evaluate the response of Ma. albidus and Me. longisetus under natural conditions in Uruguay. PMID:12941020

Calliari, D; Sanz, K; Martínez, M; Cervetto, G; Gómez, M; Basso, C

2003-09-01

204

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

205

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

206

Effect of eutrophication on species composition and growth of freshwater mussels (Mollusca, Unionidae) in Lake Hallwil (Aargau, Switzerland)  

Microsoft Academic Search

Species composition, relative abundance and life history of unionid mussels are compared between 1982–86 and 1915–19 in Lake Hallwil and the outflowing brook. The recent samples of unionid mussels were collected by divers, whereas the older ones were from a shell collection. The motivation for the comparison was that the trophic degree of the lake has changed since the beginning

Hubert E. Arter

1989-01-01

207

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

PubMed

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

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

2009-07-01

208

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

Microsoft Academic Search

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

J. A. Camargo; J. V. Ward

1995-01-01

209

Strengthening the link between climate, hydrological and species distribution modeling to assess the impacts of climate change on freshwater biodiversity.  

PubMed

To understand the resilience of aquatic ecosystems to environmental change, it is important to determine how multiple, related environmental factors, such as near-surface air temperature and river flow, will change during the next century. This study develops a novel methodology that combines statistical downscaling and fish species distribution modeling, to enhance the understanding of how global climate changes (modeled by global climate models at coarse-resolution) may affect local riverine fish diversity. The novelty of this work is the downscaling framework developed to provide suitable future projections of fish habitat descriptors, focusing particularly on the hydrology which has been rarely considered in previous studies. The proposed modeling framework was developed and tested in a major European system, the Adour-Garonne river basin (SW France, 116,000 km(2)), which covers distinct hydrological and thermal regions from the Pyrenees to the Atlantic coast. The simulations suggest that, by 2100, the mean annual stream flow is projected to decrease by approximately 15% and temperature to increase by approximately 1.2 °C, on average. As consequence, the majority of cool- and warm-water fish species is projected to expand their geographical range within the basin while the few cold-water species will experience a reduction in their distribution. The limitations and potential benefits of the proposed modeling approach are discussed. PMID:22425276

Tisseuil, C; Vrac, M; Grenouillet, G; Wade, A J; Gevrey, M; Oberdorff, T; Grodwohl, J-B; Lek, S

2012-05-01

210

Generation of reactive oxygen species undergoing redox cycle of nostocine A: a cytotoxic violet pigment produced by freshwater cyanobacterium Nostoc spongiaeforme.  

PubMed

Nostocine A (1) is an extracellular cytotoxic violet pigment produced by the freshwater cyanobacterium, Nostoc spongiaeforme TISTR 8169. Treatment with 1 was found to accelerate the generation of reactive oxygen species (ROS) in the green alga, Chlamydomonas reinhardtii, in the light. In vitro analysis revealed that 1 specifically eliminated superoxide radical anion (O(2)(-)) among several ROS tested. During the course of the reaction, oxygen (O(2)) was simultaneously synthesized and the O(2) synthesizing rate increased with the amount of 1 added. In contrast, O(2)(-) generation occurred when NADPH or NADH was added to a solution of 1 under aerobic condition. The reduction potential of 1 is very similar to that of O(2) indicating that 1 and O(2) can easily exchange electrons depending on the mass balance between their oxidized and reduced forms. Based on these results, the following hypothesis is formulated for the mechanism of intracellular ROS generation by treatment with 1: 1 taken into the target cells is reduced specifically by intracellular reductants such as NAD(P)H. When the O(2) level is sufficiently higher than that of 1, the reduced product of 1 is immediately oxidized by O(2). This is accompanied by the synthesis of O(2)(-) from O(2). The generation of O(2)(-) successively occurs, undergoing repeated redox cycles of 1, when the levels of the reductant and O(2) are still dominant to promote these reactions. This similar intracellular ROS generation mechanism to that of paraquat may cause the cytotoxicity. PMID:15099903

Hirata, Kazumasa; Yoshitomi, Sayaka; Dwi, Susilaningsih; Iwabe, Osamu; Mahakant, Aparat; Polchai, Jirapatch; Miyamoto, Kazuhisa

2004-05-13

211

Sensitivity of the glochidia (larvae) of freshwater mussels to copper: assessing the effect of water hardness and dissolved organic carbon on the sensitivity of endangered species.  

PubMed

The assessment of the potential impact of waterborne contaminants on imperilled freshwater mussels is needed. Acute copper toxicity was assessed in a standardized soft water (hardness 40-48 mg CaCO(3)equivalents L(-1)) using the larvae (glochidia) from three common and six (Canadian) endangered mussel species. The resulting 24h EC50s ranged from 7 to 36 microg Cu L(-1), with the EC50s of two endangered species <10 microg Cu L(-1). Acute copper sensitivity was also determined in Ptychobranchus fasciolaris, a species that employs conglutinates (packets of glochidia) in its reproductive strategy. Conglutinates were found to provide significant protection from acute copper exposure as the EC50 of the encased glochidia was more than four-fold higher than freed glochidia (72.6 microg Cu L(-1) vs. 16.3 microg Cu L(-1)). The glochidia from two endangered species, Epioblasma triquetra and Lampsilis fasciola, were used to examine the influence of water hardness and dissolved organic carbon (DOC) on copper sensitivity. Exposures in moderately-hard water (165 mg CaCO(3) L(-1)) demonstrated that an increase in water hardness resulted in a significant reduction in copper sensitivity. For example, in L. fasciola the 24 h EC50s were 17.6 (14.2-22.6) microg Cu L(-1) and 50.4 (43.5-60.0) microg Cu L(-1) in soft water and moderately-hard water, respectively. The addition of DOC (as Aldrich Humic Acid) also resulted in a significant decrease in Cu sensitivity, such that a 10-fold increase in the EC50 of E. triquetra was observed when the reconstituted soft water was augmented with 1.6 mg DOC L(-1). To determine if current water quality regulations for copper would protect all glochidia, the USEPA's Biotic Ligand Model (BLM) was used to derive water quality criteria for these exposures. While BLM-derived criteria for the soft water exposures indicate that protection would be marginal for the sensitive endangered species, the criteria derived for the DOC exposures suggest that the natural complexity of most natural waters in Southern Ontario (Canada) will provide glochidia with protection from acute copper exposure. PMID:18490065

Gillis, Patricia L; Mitchell, Rebecca J; Schwalb, Astrid N; McNichols, Kelly A; Mackie, Gerald L; Wood, Chris M; Ackerman, Josef D

2008-06-23

212

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.

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

2008-01-01

213

Efficacy of New Inexpensive Cyanobacterial Biofertilizer Including its Shelflife  

Microsoft Academic Search

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

M. N. Jha; A. N. Prasad

2006-01-01

214

FISH in micronucleus test demonstrates aneugenic action of rotenone in a common freshwater fish species, Nile tilapia (Oreochromis niloticus).  

PubMed

Aneuploidies are numerical genetic alterations that lead to changes in the normal number of chromosomes due to abnormal segregation during cell division. This type of alteration can occur spontaneously or as a result of exposure to mutagenic agents. The presence of these agents in the environment has increased concern about potential damage to human health. Rotenone, derived from plants of the genera Derris and Lonchocarpus, is a product that is used all over the world as a pesticide and piscicide. Before establishing its potential and efficiency for these purposes, it is essential to know more about the possible adverse effects that it may cause. The current work aimed to evaluate the mutagenic potential of rotenone using fish from the species Oreochromis niloticus, as well as to help in understanding its action mechanism. Our results showed the mutagenic potential of rotenone evidenced by increased formation of micronuclei and nuclear buds at low doses of exposure. The use of fluorescence in situ hybridisation technique made it possible to measure the aneugenic potential of the substance, probably due to its impairment of mitotic spindle formation. PMID:24618992

Melo, Karina M; Grisolia, Cesar K; Pieczarka, Julio C; de Souza, Ludmilla R; Filho, José de Souza; Nagamachi, Cleusa Y

2014-05-01

215

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

PubMed

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

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

2012-05-01

216

Cyanobacterial Cyclopeptides as Lead Compounds to Novel Targeted Cancer Drugs  

PubMed Central

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

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

2010-01-01

217

Microbial community changes elicited by exposure to cyanobacterial allelochemicals.  

PubMed

An increasing body of evidence points out that allelopathy may be an important process shaping microbial communities in aquatic ecosystems. Cyanobacteria have well-documented allelopathic properties, mainly derived from the evaluation of the activity of allelopathic extracts or pure compounds towards monocultures of selected target microorganisms. Consequently, little is known regarding the community dynamics of microorganisms associated with allelopathic interactions. In this laboratory-based study, a Microcystis spp.-dominated microbial community from a freshwater lake was exposed, for 15 days, to exudates from the cyanobacterium Oscillatoria sp. strain LEGE 05292 in laboratory conditions. This cyanobacterium is known to produce the allelochemicals portoamides, which were among the exuded compounds. The community composition was followed (by means of polymerase chain reaction followed by denaturing gradient gel electrophoresis and microscopic analyses) and compared to that of a non-exposed situation. Following exposure, clear differences in the community structure were observed, in particular for cyanobacteria and unicellular eukaryotic taxa. Interestingly, distinct Microcystis genotypes present in the community were differentially impacted by the exposure, highlighting the fine-scale dynamics elicited by the exudates. These results support a role for cyanobacterial allelochemicals in the structuring of aquatic microbial communities. PMID:21947429

Leão, Pedro N; Ramos, Vitor; Vale, Micaela; Machado, João P; Vasconcelos, Vitor M

2012-01-01

218

Substrate and/or substrate-driven changes in the abundance of methanogenic archaea cause seasonal variation of methane production potential in species-specific freshwater wetlands.  

PubMed

There are large temporal and spatial variations of methane (CH4) emissions from natural wetlands. To understand temporal changes of CH4 production potential (MPP), soil samples were collected from a permanently inundated Carex lasiocarpa marsh and a summer inundated Calamagrostis angustifolia marsh over the period from June to October of 2011. MPP, dissolved organic carbon (DOC) concentration, abundance and community structure of methanogenic archaea were assessed. In the C. lasiocarpa marsh, DOC concentration, MPP and the methanogen population showed similar seasonal variations and maximal values in September. MPP and DOC in the C. angustifolia marsh exhibited seasonal variations and values peaked during August, while the methanogen population decreased with plant growth. Methanogen abundance correlated significantly (P?=?0.02) with DOC only for the C. lasiocarpa marsh. During the sampling period, the dominant methanogens were the Methanosaetaceae and Zoige cluster I (ZC-?) in the C. angustifolia marsh, and Methanomicrobiales and ZC-? in the C. lasiocarpa marsh. MPP correlated significantly (P?=?0.04) with DOC and methanogen population in the C. lasiocarpa marsh but only with DOC in the C. angustifolia marsh. Addition of C. lasiocarpa litter enhanced MPP more effectively than addition of C. angustifolia litter, indicating that temporal variation of substrates is controlled by litter deposition in the C. lasiocarpa marsh while living plant matter is more important in the C. angustifolia marsh. This study indicated that there was no apparent shift in the dominant types of methanogen during the growth season in the species-specific freshwater wetlands. Temporal variation of MPP is controlled by substrates and substrate-driven changes in the abundance of methanogenic archaea in the C. lasiocarpa marsh, while MPP depends only on substrate availability derived from root exudates or soil organic matter in the C. angustifolia marsh. PMID:24535255

Liu, Deyan; Ding, Weixin; Yuan, Junji; Xiang, Jian; Lin, Yongxin

2014-05-01

219

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

SciTech Connect

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

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

1997-01-01

220

Aggregation Phenomena in Cyanobacterial, Stromatolite Analogues  

Microsoft Academic Search

Earth's biological history is largely the story of microbial evolution. If one is to understand the evolution of such fundamental processes as photosynthesis, it is imperative to recognize and interpret microbial fossils. To these ends, we examine the forces that shape a modern cyanobacterial mat from the hot springs of Yellowstone that is thought to grow in a manner similar

Alexander Petro; Tanja Bosak; Biqing Liang; Daniel Rothman

221

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

NASA Astrophysics Data System (ADS)

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

Fleming, Erich D.; Prufert-Bebout, Leslie

2010-06-01

222

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

223

Are cyanobacterial blooms trophic dead ends?  

PubMed

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

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

2013-06-01

224

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

225

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

226

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

227

[Identification of two cyanobacterial strains isolated from the Kotel'nikovskii hot spring of the Baikal rift].  

PubMed

Two cyanobacterial strains, Pseudanabaena sp. 0411 and Synechococcus sp. 0431, were isolated from a sample collected in the Kotel'nikovskii hot spring of the Baikal rift. According to the results of light and transmission electron microscopy, as well as of the phylogenetic analysis of the 16S rRNA gene, these cyanobacteria were classified as Pseudanabaena sp. nov. and Synechococcus bigranulatus Skuja. The constructed phylogenetic tree shows that the studied strains are positioned in the clades of cyanobacteria isolated from hydrothermal vents of Asia and New Zealand, separately from marine and freshwater members of these genera, including those isolated from Lake Baikal. PMID:18683660

Sorokovnikova, E G; Tikhonova, I V; Belykh, O I; Klimenkov, I V; Likhoshva?, E V

2008-01-01

228

Using mitochondrial and ribosomal DNA sequences to test the taxonomic validity of Clinostomum complanatum Rudolphi, 1814 in fish-eating birds and freshwater fishes in Mexico, with the description of a new species.  

PubMed

The taxonomic history and species composition of the genus Clinostomum has been unstable. Two species, Clinostomum complanatum Rudolphi, 1814 and Clinostomum marginatum Rudolphi, 1819, have been particularly problematic and its validity has been disputed for nearly 200 years. In this paper, we have made use of an integrative taxonomy approach, and we used, in first instance, DNA sequences of two genes (cox1 and ITS) to test the validity of C. complanatum, a species apparently widely distributed in Mexico and to link the metacercariae and adult forms of the recognized species of Clinostomum. Combining molecular data with morphology, host association, and geographical distribution, we searched for the potential existence of undescribed species. A new species of Clinostomum is described based on adults found in the mouthy cavity of three species of fish-eating birds as well as in metacercariae found in freshwater and estuarine fishes. A few morphological characteristics distinguish the new species from other congeners even though reciprocal monophyly in a phylogenetic tree based on maximum-likelihood and Bayesian analysis, genetic divergence, and a multivariate analysis of variance and a principal component analysis of 18 morphometric traits for adults and metacercariae demonstrates the validity of the new species. Based on our results, it seems that C. complanatum is not currently distributed in Mexico, although this requires further verification with a more thoroughful sampling in other areas of the country, but it is plausible to support the hypothesis that C. marginatum is the American form, as previously suggested by other authors. PMID:23708398

Sereno-Uribe, Ana L; Pinacho-Pinacho, Carlos D; García-Varela, Martín; de León, Gerardo Pérez-Ponce

2013-08-01

229

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

Microsoft Academic Search

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

MAYUVA AREEKIJSEREE; ARUNEE ENGKAGUL; SATIT KOVITVADHI; UTHAIWAN KOVITVADHI; AMARA THONGPAN; KRISNA RUNGRUANGSAK-TORRISSEN

2006-01-01

230

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

Microsoft Academic Search

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

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

231

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

232

Cyanobacterial toxin degrading bacteria: who are they?  

PubMed

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

233

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

PubMed

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

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

2014-01-15

234

Global diversity of crabs (Crustacea: Decapoda: Brachyura) in freshwater  

Microsoft Academic Search

An assessment of the global freshwater crab diversity is presented. A total of 1,476 species in 14 families are currently\\u000a known from all zoogeographical regions (except Antarctica), including 1,306 species in eight exclusively freshwater families\\u000a (Pseudothelphusidae, Trichodactylidae, Potamonautidae, Deckeniidae, Platythelphusidae, Potamidae, Gecarcinucidae and Parathelphusidae).\\u000a Estimates of true freshwater crab diversity including likely numbers of undescribed taxa suggest that the field

Darren C. J. Yeo; Peter K. L. Ng; Neil Cumberlidge; Célio Magalhães; Savel R. Daniels; Martha R. Campos

2008-01-01

235

Prospects for monitoring freshwater ecosystems towards the 2010 targets  

PubMed Central

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

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

2005-01-01

236

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

PubMed Central

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

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

2008-01-01

237

A review of the use of sonication to control cyanobacterial blooms.  

PubMed

The development of cyanobacterial blooms in water bodies imparts undesirable characteristics to the water such as odours, tastes and the potential presence of toxins. Several chemical and physical methods have been used to control the blooms, but have limitations in terms of pollution and application on a large scale. A more recent approach has been the use of sonication in the control of cyanobacteria (also referred to as blue-green algae). This paper reviews current advancements in research on using sonication to control cyanobacteria, particularly Microcystis aeruginosa, as it is a prevalent and a major bloom-forming toxic species. The impact of sonication on the structure and function of M. aeruginosa is discussed, including the influence of sonication parameters such as power intensity, frequency and exposure time. Alternate strategies of cyanobacterial control in combination with sonication are also reviewed. PMID:22727861

Rajasekhar, Pradeep; Fan, Linhua; Nguyen, Thang; Roddick, Felicity A

2012-09-15

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

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

240

Early cyanobacterial fossil record: preservation, palaeoenvironments and identification  

Microsoft Academic Search

The cyanobacterial fossil record is among the oldest for any group of organisms, possibly reaching back to 3500 Ma ago. The molecular phylogeny of cyanobacteria is complementary to the fossil findings, confirming the antiquity of the group, the role of cyanobacteria in the evolution of planetary primary production, and the symbiotic origins of plastids in algae and plants from cyanobacterial

Stjepko Golubic; Lee Seong-Joo

1999-01-01

241

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.

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

2008-01-01

242

Co-occurrence of beta-N-methylamino-L-alanine, a neurotoxic amino acid with other cyanobacterial toxins in British waterbodies, 1990-2004.  

PubMed

The neurotoxic amino acid, beta-N-methylamino-L-alanine, was found to be present in all of 12 analysed samples of cyanobacterial blooms, scums and mats, which had been collected in seven years between 1990 and 2004 inclusive and stored at -20 degrees C. BMAA identification was by high performance liquid chromatography with fluorescence detection and by triple quadrapole mass spectrometry after derivatization. The samples originated from 11 freshwater lakes and 1 brackish waterbody, used either for drinking water, recreation, or both. BMAA was present at between 8 and 287 microg g(-1) cyanobacterial dry weight and was present as both the free amino acid and associated with precipitated proteins. Ten of the samples contained additional cyanotoxins (including microcystins, anatoxin-a, nodularin and saxitoxin) at the time of sample collection. Five of the samples were associated with animal deaths, attributable at the time of sample collection, to microcystins, nodularin or anatoxin-a. The data demonstrate the presence of BMAA by high performance liquid chromatography and mass spectrometry in a diverse range of cyanobacterial bloom samples from high resource waterbodies. Furthermore, samples collected over several years shows that BMAA can co-occur with other known cyanotoxins in such waterbodies. Health risk assessment of cyanobacterial BMAA in waterbodies is suggested. PMID:18237305

Metcalf, James S; Banack, Sandra Anne; Lindsay, Jaime; Morrison, Louise F; Cox, Paul Alan; Codd, Geoffrey A

2008-03-01

243

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

Microsoft Academic Search

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

Hannu Lehtonen; Martti Rask; Susanna Pakkasmaa; Trygve Hesthagen

2008-01-01

244

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

PubMed Central

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

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

2013-01-01

245

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.

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

2009-01-01

246

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

PubMed

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

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

1998-12-01

247

A Natural View of Microbial Biodiversity within Hot Spring Cyanobacterial Mat Communities  

PubMed Central

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, David M.; Ferris, Michael J.; Nold, Stephen C.; Bateson, Mary M.

1998-01-01

248

A Comparison of Freshwater Macroinvertebrate Communities on Small Caribbean Islands  

NSDL National Science Digital Library

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

DAVID BASS (;)

2003-11-01

249

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...

250

Cyanobacterial neurotoxin ?-N-methylamino-L-alanine (BMAA) in shark fins.  

PubMed

Sharks are among the most threatened groups of marine species. Populations are declining globally to support the growing demand for shark fin soup. Sharks are known to bioaccumulate toxins that may pose health risks to consumers of shark products. The feeding habits of sharks are varied, including fish, mammals, crustaceans and plankton. The cyanobacterial neurotoxin ?-N-methylamino-L-alanine (BMAA) has been detected in species of free-living marine cyanobacteria and may bioaccumulate in the marine food web. In this study, we sampled fin clips from seven different species of sharks in South Florida to survey the occurrence of BMAA using HPLC-FD and Triple Quadrupole LC/MS/MS methods. BMAA was detected in the fins of all species examined with concentrations ranging from 144 to 1836 ng/mg wet weight. Since BMAA has been linked to neurodegenerative diseases, these results may have important relevance to human health. We suggest that consumption of shark fins may increase the risk for human exposure to the cyanobacterial neurotoxin BMAA. PMID:22412816

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

2012-02-01

251

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.

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

2003-01-01

252

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

253

Photocatalytic degradation of cyanobacterial microcystin toxins in water.  

PubMed

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

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

1998-12-01

254

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.

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

2012-01-01

255

Monitoring Biological Invasions in Freshwater Habitats  

Microsoft Academic Search

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

Montserrat Vilà; Emili García-Berthou

256

Prevalence of chemical defenses among freshwater plants.  

PubMed

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

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

2005-05-01

257

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

258

Freshwater phytoplankton quantification by chlorophyll a: a comparative study of in vitro, in vivo and in situ methods.  

PubMed

Standard ISO method for chlorophyll a quantification (extraction into ethanol, spectrophotometrical quantification at 665 and 750 nm), spectrofluorometry (reader for 96 wells, excitation 410 nm, emission 670 nm), and a submersible fluorescence probe for in situ phytoplankton quantification (excitation 410, 525, 570, 590, and 610 nm, emission 685 nm) were compared in different freshwater environments-reservoirs and rivers. The ISO method is accepted as a standard method but requires sample handling and transport to the laboratory. Spectrofluorometry is a sensitive method, even for natural phytoplankton populations. Nevertheless, it cannot be recommended for the quantification of cyanobacterial water blooms because colonial and filamentous species such as Microcystis, Anabaena, or Aphanizomenon display unacceptable variability (18-33%). The submersible probe featured high correlation with a standard ISO method (r=0.97, P<0.05). This probe can provide the selective measurement of technologically important phytoplankton groups like cyanobacteria, diatoms, green algae, and cryptophytes in lake vertical profiles of up to 100 m. The limitation of this instrument is the possible reabsorption of the light signal, e.g. in the presence of humic substances, or dense algal blooms. The use of submersible probes for in situ phytoplankton quantification can be recommended as a sensitive tool for water management, especially in the case of drinking water resources. PMID:14723919

Gregor, J; Marsálek, B

2004-02-01

259

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-)

260

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

National Technical Information Service (NTIS)

Increased demand has pushed extensive aquaculture towards intensively operated production systems, commonly resulting in eutrophic conditions and cyanobacterial blooms. This review summarizes those cyanobacterial secondary metabolites that can cause undes...

G. L. Boyer J. L. Smith P. V. Zimba

2008-01-01

261

AN INTRODUCTION TO THE FRESHWATER FISH COMMUNITIES OF CORCOVADO NATIONAL PARK, COSTA RICA  

Microsoft Academic Search

The distributional pattern and ecology of each species of the freshwater fish communities surrounding the Sirena station of Corcovado Park were investigated during the early rainy season of 1982. Thirty species were observed or collected in freshwaters of the park, and an additional 10 species were restricted to intertidal regions. Peripheral division and invading marine fishes were major integral components

Kirk O. Winemiller

262

Freshwater Rotifera from plankton of the Kerguelen Islands (Subantarctica)  

Microsoft Academic Search

During the austral summer 1997\\/98, a survey was made of a series of freshwater bodies on the Kerguelen Islands, Subantarctica (49° S–69° E), in the area of Port-aux- Français and Val Studer. The rotifer fauna from plankton of 17 lentic freshwaters is listed and commented upon. Species richness (39 taxa) and species diversity are fairly low. Only 6 taxa are

Willem H. De Smet

2001-01-01

263

2. Genome rearrangement and speciation in freshwater algae  

Microsoft Academic Search

Speciation problems are reviewed in the context of biogeography of fresh-water algae. Currently accepted species concept in\\u000a phycology is based on morphological characters, and according to this concept, most freshwater algal species are considered\\u000a cosmopolitan. This implies whether they have a highly efficient means of dispersal or their morphological characters are very\\u000a static through a long evolutionary time. Recent studies

Terunobu Ichimura

1996-01-01

264

A new species of Mymarothecium and new host and geographical records for M. viatorum (Monogenea: Dactylogyridae), parasites of freshwater fishes in Brazil.  

PubMed

Mymarothecium boegeri sp. n. (Monogenea: Dactylogyridae) is described from the gills of Colossoma macropomum Cuvier (Characidae), collected from the aquaria of the "Centro de Pesquisas em Aquicultura, Departamento Nacional de Obras Contra as Secas (DNOCS)", Pentecoste City, State of Ceará, Brazil. Mymarothecium viatorum Boeger, Piasecki et Sobecka, 2002 is reported from the type host, Piaractus brachypomus (Cuvier) (Characidae) and from a new host, P. mesopotamicus (Holmberg) (Characidae), confirming the occurrence of M. viatorum in the Neotropical Region. The new species differs from the congeneric species in the structure of male copulatory complex; it is more closely related to M. viatorum by the presence of a posteromedial projection on ventral bar. PMID:16405294

Cohen, Simone Chinicz; Kohn, Anna

2005-11-01

265

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

PubMed

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

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

2004-03-01

266

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

PubMed Central

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

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

2011-01-01

267

The role of the freshwater shrimp Caridina nilotica (Roux) in the diet of the major commercial fish species in Lake Victoria, Tanzania  

Microsoft Academic Search

The major commercial fish species of Lake Victoria at the present time are Lates niloticus, Oreochromis niloticus and Rastrineobola argentea. The contribution of Caridina nilotica in their diet was studied in the Tanzanian waters of Lake Victoria between March, 1999 and January, 2002. Stomach samples were collected during routine bottom trawl surveys in Tanzania. The results show that haplochromines dominate

Y. L. Budeba; I. G. Cowx

2007-01-01

268

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...

269

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.

2013-01-01

270

Influence of site, season and year on contributions made by marine, estuarine, diadromous and freshwater species to the fish fauna of a temperate Australian estuary  

Microsoft Academic Search

Catches obtained at regular intervals by beach seining, gill netting and otter trawling at ten, four and six sites, respectively, have been used to determine the contribution of the different species and life-cycle categories of fish to the ichthyofauna of the large Swan Estuary in temperate south-western Australia between February 1977 and December 1981. These data were also examined to

N. R. Loneragan; I. C. Potter; R. C. J. Lenanton

1989-01-01

271

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

272

Cyanobacterial NDH-1 complexes: novel insights and remaining puzzles.  

PubMed

Cyanobacterial NDH-1 complexes belong to a family of energy converting NAD(P)H:Quinone oxidoreductases that includes bacterial type-I NADH dehydrogenase and mitochondrial Complex I. Several distinct NDH-1 complexes may coexist in cyanobacterial cells and thus be responsible for a variety of functions including respiration, cyclic electron flow around PSI and CO(2) uptake. The present review is focused on specific features that allow to regard the cyanobacterial NDH-1 complexes, together with NDH complexes from chloroplasts, as a separate sub-class of the Complex I family of enzymes. Here, we summarize our current knowledge about structure of functionally different NDH-1 complexes in cyanobacteria and consider implications for a functional mechanism. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts. PMID:21035426

Battchikova, Natalia; Eisenhut, Marion; Aro, Eva-Mari

2011-08-01

273

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

PubMed Central

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

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

2011-01-01

274

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

Microsoft Academic Search

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

Changfu Zhu; Tanja Gerjets; Gerhard Sandmann

2007-01-01

275

Effects of barley straw ( Hordeum vulgare ) on freshwater and brackish phytoplankton and cyanobacteria  

Microsoft Academic Search

A short-term laboratory study was conductedto investigate the effect of barley strawin controlling several common phytoplanktonand cyanobacterial species. Following aone-month incubation of barley straw incoarsely filtered fresh Potomac River andbrackish Patuxent River waters, the growthof six autotrophic taxa was followed inculture. Barley straw slurry reduced theyield of three taxa (Ankistrodesmusfalcatus, Chlorella capsulata, Isochrysis sp.) in comparison withcultures not receiving the

Emily F. Brownlee; Stella G. Sellner; Kevin G. Sellner

2003-01-01

276

Health risk assessment for cyanobacterial toxins in seafood.  

PubMed

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

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

2012-03-01

277

Health Risk Assessment for Cyanobacterial Toxins in Seafood  

PubMed Central

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

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

2012-01-01

278

Episodic Cyanobacterial Expansions During Permian-Triassic Biotic Crisis at Meishan in South China  

NASA Astrophysics Data System (ADS)

The Permian-Triassic (P-Tr) mass extinction was the most severe biotic crisis in the Phanerozoic, eliminating over 90% of all marine species and 70% of terrestrial vertebrate families. The pattern of the marine mass extinction near the P-Tr boundary is still debated. A stepwise multi-phase biotic extinction proposed on the basis of several southern China sections has recently been challenged by a proposal of a main sudden biotic crisis. Reconciling this debate is necessary in order to estimate the duration (abruptness) of the extinction and to evaluate proposed mechanisms. In contrast with the previous investigations focusing on faunal fossil records, we have conducted a survey of microbial biomarkers (molecular fossils) in sedimentary rocks spanning the P-Tr boundary at Meishan sections in South China where the GSSP was defined. By using the powerful techniques of gas chromatography-mass spectrometry (GC-MS) and GC-combustion-isotope ratio MS, we are able to identify a series of biomarkers and measure the compound-specific carbon isotope composition. In the saturated hydrocarbon fraction of solvent extracts of the sedimentary rocks, a series of 2?-methylhopanes (2-MHP) derived from cyanobacterial 2-methyl-bacteriohopanepolyols precursors are present. The ratio of 2-MHP to hopanes (2-MHP index) reflects the abundance of cyanobacterial component relative to the general bacterial population. The striking aspect of the Meishan 2-MHP profile is the presence of two distinct maxima (beds 26 and 29) within the investigated intervals. Significantly, the 2-MHP indices are stratigraphically coupled with the faunal extinction probability; minima in 2-MHP indices coincide with, or slightly precede, the times of maximum faunal extinction (beds 25 and 28), while maxima in 2-MHP indices clearly lag extinction. It appears that faunal and microbial turnover was closely related, probably reflecting their ecological coupling and/or distinct but coincidental responses to external environmental forcings. The large changes in cyanobacterial population abundances, coupled with faunal mass extinction, likely signify a stepwise multi-phase environmental perturbation. In addition, the two cyanobacterial expansions are characterised by two strong negative shifts (about 9 per mil in ?13C values of n-C19 n-alkanes, likely derived from phytoplankton and/or bacteria. In contrast, positive excursions are observed in association with the two horizons of faunal mass extinction. The large fluctuation of n-alkane ?13C signature clearly suggests major, episodic changes in either micro-organism inputs or sedimentary environmental conditions during the P-Tr biotic crisis.

Xie, S.; Pancost, R.; Huang, X.; Jiao, D.; Lu, L.; Huang, J.; Wang, H.; Yang, F.; Yin, H.; Evershed, R.

2005-12-01

279

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

280

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

PubMed

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

281

The Amount of Space Available for Marine and Freshwater Fishes.  

National Technical Information Service (NTIS)

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

M. H. Horn

1972-01-01

282

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

283

Identifying Canadian Freshwater Fishes through DNA Barcodes  

PubMed Central

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

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

2008-01-01

284

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

PubMed Central

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

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

2010-01-01

285

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

286

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

PubMed Central

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

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

2013-01-01

287

Effect of incubation temperature on the detection of thermophilic campylobacter species from freshwater beaches, nearby wastewater effluents, and bird fecal droppings.  

PubMed

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

Khan, Izhar U H; Hill, Stephen; Nowak, Eva; Edge, Thomas A

2013-12-01

288

Deep-ocean origin of the freshwater eels  

PubMed Central

Of more than 800 species of eels of the order Anguilliformes, only freshwater eels (genus Anguilla with 16 species plus three subspecies) spend most of their lives in freshwater during their catadromous life cycle. Nevertheless, because their spawning areas are located offshore in the open ocean, they migrate back to their specific breeding places in the ocean, often located thousands of kilometres away. The evolutionary origin of such enigmatic behaviour, however, remains elusive because of the uncertain phylogenetic position of freshwater eels within the principally marine anguilliforms. Here, we show strong evidence for a deep oceanic origin of the freshwater eels, based on the phylogenetic analysis of whole mitochondrial genome sequences from 56 species representing all of the 19 anguilliform families. The freshwater eels occupy an apical position within the anguilliforms, forming a highly supported monophyletic group with various oceanic midwater eel species. Moreover, reconstruction of the growth habitats on the resulting tree unequivocally indicates an origination of the freshwater eels from the midwater of the deep ocean. This shows significant concordance with the recent collection of mature adults of the Japanese eel in the upper midwater of the Pacific, suggesting that they have retained their evolutionary origin as a behavioural trait in their spawning areas.

Inoue, Jun G.; Miya, Masaki; Miller, Michael J.; Sado, Tetsuya; Hanel, Reinhold; Hatooka, Kiyotaka; Aoyama, Jun; Minegishi, Yuki; Nishida, Mutsumi; Tsukamoto, Katsumi

2010-01-01

289

Aggregation Phenomena in Cyanobacterial Analogues of Ancient Stromatolites  

Microsoft Academic Search

If one is to understand and time the evolution of such fundamental processes as photosynthesis, it is imperative to recognize and interpret microbial fossils. This goal is challenging because many of the oldest putative fossils are only identified as biotic by a distinctive morphology. To this end, we examine the forces that shape modern, cone-forming cyanobacterial mats that are thought

T. Bosak; A. P. Petroff; M. Sim; D. H. Rothman

2008-01-01

290

Carbon pools and isotopic trends in a hypersaline cyanobacterial mat  

Microsoft Academic Search

The fine-scale depth distribution of major carbon pools and their stable carbon isotopic signatures ( ? 13 C) were determined in a cyanobacterial mat (Salin-de-Giraud, Camargue, France) to study early diagenetic alterations and the carbon preservation potential in hypersaline mat ecosystems. Particular emphasis was placed on the geochemical role of extracellular polymeric substances (EPS). Total carbon (C tot ), organic

A. WIELAND; T. PAPE; J. MÖBIUS; W. MICHAELIS

2008-01-01

291

Monitoring Survival and Preservation of Recent Cyanobacterial Mats  

Microsoft Academic Search

Through geobiological evolution cyanobacterial mats have played a fundamental role through the development of early microbial carbonate ecosystems and through the sustainment of major biogeochemical cycling in the biosphere; nonetheless their sedimentary record is relatively modest in comparison with their biological impact; this apparent under-representation in the fossil record may be due to their intrinsic poor preservation potential but also

Elizabeth Chacon; Alicia Negron-Mendoza; Claudia Camargo

2010-01-01

292

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...

293

News from a small island – first record of a freshwater shrimp (Decapoda, Atyidae, Caridina) from Peleng, Banggai Islands, Indonesia  

Microsoft Academic Search

The Indonesian island Sulawesi is well known for its fascinating fauna. Among the atyid and palaemonid freshwater shrimps described from Sulawesi are also a number of endemic species. In contrast, freshwater shrimps have never been reported from the nearby and smaller Peleng Island. Here we describe Caridina thomasi sp. nov. as a first record of an atyid freshwater shrimp from

Kristina von Rintelen; Andreas Karge; Werner Klotz

2008-01-01

294

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

295

Removal of cyanobacterial toxins by sediment passage  

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

296

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

PubMed

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

Nguyen, T T T; Sunnucks, P

2012-03-01

297

Molecular characterization and expression analysis of three hypoxia-inducible factor alpha subunits, HIF-1?/2?/3? of the hypoxia-sensitive freshwater species, Chinese sucker.  

PubMed

Hypoxia-inducible factors (HIFs) are transcription factors that respond to changes in oxygen tension in the cellular environment. In this study, we identified full-length cDNAs of HIF-1?, HIF-2? and HIF-3? in an endangered hypoxia-sensitive fish species, Chinese sucker. The HIF-1?/2?/3? cDNAs are 3890, 3230 and 3374 bp in length, encoding 780, 782 and 632 amino acid residues, respectively. The real-time PCR results suggested that HIF-1? and HIF-3? mRNAs were highly expressed in liver and gonads, followed by spleen and muscle. Moreover, HIF-1? and HIF-3? transcription factors revealed similar developmental expression patterns, with the lowest expression at 48h post-fertilization, and reaching the highest expression level at 360 h post-fertilization. Short-term hypoxia exposure (2.2, 2.8 and 3.2mg/L dissolved oxygen for 24h) increased mRNA levels of HIF-1? and HIF-3?. HIF-2? mRNA showed similar expression patterns with that of HIF-1? and HIF-3?, however, its expression was extremely low in the spatio-temporal expression patterns and hypoxia treatment. This is the first report describing the potential to identify hypoxia-sensitive/tolerant fishes according to the number of the serine residues of fish oxygen-dependent degradation (ODD) domain. It was suggested that Cyprinomorpha fishes, with less than 40 serine residues in fish ODD domain were hypoxia-sensitive fishes and more than 40 serine residues in this domain were hypoxia-tolerant fishes. PMID:22342256

Chen, Nan; Chen, Li Ping; Zhang, Jie; Chen, Cheng; Wei, Xin Lan; Gul, Yasmeen; Wang, Wei Min; Wang, Huan Ling

2012-04-25

298

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.

299

Global diversity of sponges (Porifera: Spongillina) in freshwater  

Microsoft Academic Search

Porifera is a primarily marine phylum comprising more than 15,000 species. The successful and wide adaptive radiation of freshwater\\u000a sponges (Haplosclerida: Spongillina) has resulted in the colonization of an extremely wide variety of habitats at all latitudes.\\u000a Colonization is dated back to the Mesozoic, and the mono- or poly-phyletism of Spongillina, and the number of potential sponge\\u000a invasions into freshwater

R. Manconi; R. Pronzato

300

Global diversity of sponges (Porifera: Spongillina) in freshwater  

Microsoft Academic Search

Porifera is a primarily marine phylum comprising more than 15,000 species. The successful and wide adaptive radiation of freshwater\\u000a sponges (Haplosclerida: Spongillina) has resulted in the colonization of an extremely wide variety of habitats at all latitudes.\\u000a Colonization is dated back to the Mesozoic, and the mono- or poly-phyletism of Spongillina, and the number of potential sponge\\u000a invasions into freshwater

R. Manconi; R. Pronzato

2008-01-01

301

Restricted-Range Fishes and the Conservation of Brazilian Freshwaters  

PubMed Central

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

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

2010-01-01

302

Freshwater and Marine Image Bank  

NSDL National Science Digital Library

The Freshwater and Marine Image Bank is an ongoing digital collection of images related to freshwater and marine topics, in all their diversity. It includes images of fish, shellfish, and marine mammals, pictures of fish hatcheries and dams and vessels, materials related to polar exploration, regional and traditional fisheries, and limnological (freshwater) subjects. Its scope is global.

Washington, University O.

2010-02-16

303

Age at recruitment of Hawaiian freshwater gobies  

Microsoft Academic Search

Synopsis  Very little is known about the dynamics of native Hawaiian stream fishes. Five species are restricted, as adults, to freshwater\\u000a streams and estuaries on the major islands of the Hawaiian archipelago. This paucity of information is partly due to difficulties\\u000a inherent in determination of age and subsequent determinations of life history characteristics. In the present study, we determined\\u000a the age

Richard L. Radtkel; Robert A. Kinzie; Scott D. Folsoml

1988-01-01

304

Loons in freshwater lakes  

Microsoft Academic Search

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

Judith W. McIntyre

1994-01-01

305

Freshwater Marsh. Habitat Pac.  

ERIC Educational Resources Information Center

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

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

306

Effects of harmful cyanobacteria on the freshwater pathogenic free-living amoeba Acanthamoeba castellanii.  

PubMed

Grazing is a major regulating factor in cyanobacterial population dynamics and, subsequently, considerable effort has been spent on investigating the effects of cyanotoxins on major metazoan grazers. However, protozoan grazers such as free-living amoebae can also feed efficiently on cyanobacteria, while simultaneously posing a major threat for public health as parasites of humans and potential reservoirs of opportunistic pathogens. In this study, we conducted several experiments in which the freshwater amoeba Acanthamoeba castellanii was exposed to pure microcystin-LR (MC-LR) and six cyanobacterial strains, three MC-producing strains (MC-LR, MC-RR, MC-YR, MC-WR, [Dha7] MC-RR) and three strains containing other oligopeptides such as anabaenopeptins and cyanopeptolins. Although the exposure to high concentrations of pure MC-LR yielded no effects on amoeba, all MC-producing strains inflicted high mortality rates on amoeba populations, suggesting that toxic effects must be mediated through the ingestion of toxic cells. Interestingly, an anabaenopeptin-producing strain caused the greatest inhibition of amoeba growth, indicating that toxic bioactive compounds other than MCs are of great importance for amoebae grazers. Confocal scanning microscopy revealed different alterations in amoeba cytoskeleton integrity and as such, the observed declines in amoeba densities could have indeed been caused via a cascade of cellular events primarily triggered by oligopeptides with protein-phosphatase inhibition capabilities such as MCs or anabaenopeptins. Moreover, inducible-defense mechanisms such as the egestion of toxic, MC-producing cyanobacterial cells and the increase of resting stages (encystation) in amoebae co-cultivated with all cyanobacterial strains were observed in our experiments. Consequently, cyanobacterial strains showed different susceptibilities to amoeba grazing which were possibly influenced by the potentiality of their toxic secondary metabolites. Hence, this study shows the importance of cyanobacterial toxicity against amoeba grazing and, that cyanobacteria may contain a wide range of chemical compounds capable of negatively affect free-living, herbivorous amoebae. Moreover, this is of high importance for understanding the interactions and population dynamics of such organisms in aquatic ecosystems. PMID:23333903

Urrutia-Cordero, Pablo; Agha, Ramsy; Cirés, Samuel; Lezcano, María Ángeles; Sánchez-Contreras, María; Waara, Karl-Otto; Utkilen, Hans; Quesada, Antonio

2013-04-15

307

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

Microsoft Academic Search

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

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

2012-01-01

308

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

309

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

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

1991-01-01

310

A phycocyanin probe as a tool for monitoring cyanobacteria in freshwater bodies.  

PubMed

In many countries, the presence of cyanobacteria in freshwater bodies used for both drinking water and recreational purposes is under increasing public health attention. Water managers are considering how to implement monitoring that leads to a minimization of the risks incurred by the users of potentially contaminated sites. To address this question, this study involved assessing the performance of a submersible probe for measuring phycocyanin-specific fluorescence as a function of cyanobacterial biomass, with the aim of applying it as a tool for surveillance management. Its advantages and limits compared to more traditional analyses are discussed. The monitoring of cyanobacteria in the water bodies of western France was carried out using a minifluorimeter specific to the fluorescence of phycocyanin, a pigment specific to cyanobacteria. The results are compared with the analyses recommended by the World Health Organisation (chlorophyll a and cell counting). This study based on nearly 800 samples shows a significant correlation between the phycocyanin content and the cyanobacterial biomass, expressed as the number of cells per mL (R2 = 0.73). This submersible probe is simple and rapid to use, making it possible to take into account horizontal and vertical heterogeneities in the proliferation growth. In this way, we are able to detect at an early stage the conditions that could potentially lead to a risk, in order to start sampling. Due to its sensitivity, this tool proves suitable for monitoring aimed at reducing the risks incurred by the users of contaminated sites and launching preventative actions. The use of the phycocyanin probe provides an effective tool to complement traditional analyses of cyanobacterial presence. It is suggested that a surveillance protocol based on phycocyanin concentration can significantly improved the accuracy of the extent of cyanobacterial bloom development in the light of spatial and temporal variabilities associated with these occurrences. PMID:18246219

Brient, Luc; Lengronne, Marion; Bertrand, Emilie; Rolland, Delphine; Sipel, Arnaud; Steinmann, Delphine; Baudin, Isabelle; Legeas, Michèle; Le Rouzic, Bertrand; Bormans, Myriam

2008-02-01

311

Flow-induced Development of Unicellular Cyanobacterial Mats  

NASA Astrophysics Data System (ADS)

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

Gong, J.; Tice, M. M.

2011-12-01

312

Nearly Identical Bacteriophage Structural Gene Sequences Are Widely Distributed in both Marine and Freshwater Environments  

PubMed Central

Primers were designed to amplify a 592-bp region within a conserved structural gene (g20) found in some cyanophages. The goal was to use this gene as a proxy to infer genetic richness in natural cyanophage communities and to determine if sequences were more similar in similar environments. Gene products were amplified from samples from the Gulf of Mexico, the Arctic, Southern, and Northeast and Southeast Pacific Oceans, an Arctic cyanobacterial mat, a catfish production pond, lakes in Canada and Germany, and a depth of ca. 3,246 m in the Chuckchi Sea. Amplicons were separated by denaturing gradient gel electrophoresis, and selected bands were sequenced. Phylogenetic analysis revealed four previously unknown groups of g20 clusters, two of which were entirely found in freshwater. Also, sequences with >99% identities were recovered from environments that differed greatly in temperature and salinity. For example, nearly identical sequences were recovered from the Gulf of Mexico, the Southern Pacific Ocean, an Arctic freshwater cyanobacterial mat, and Lake Constance, Germany. These results imply that closely related hosts and the viruses infecting them are distributed widely across environments or that horizontal gene exchange occurs among phage communities from very different environments. Moreover, the amplification of g20 products from deep in the cyanobacterium-sparse Chuckchi Sea suggests that this primer set targets bacteriophages other than those infecting cyanobacteria.

Short, Cindy M.; Suttle, Curtis A.

2005-01-01

313

Detection of the neurotoxin BMAA within cyanobacteria isolated from freshwater in China.  

PubMed

The cyanobacterial neurotoxin, beta-N-methylamino-l-alanine (BMAA), has been suggested as an important environmental factor for neurodegenerative disease such as amyotrophic lateral sclerosis- Parkinsonism dementia complex (ALS/PDC) in Guam. BMAA was detected within the majority of cyanobacterial isolates surveyed in both free and symbiotic cyanobacteria, living in freshwater as well as marine environments. In this study, we report two methods using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS) each coupled with a different type of hydrophilic interaction liquid chromatography (HILIC) column to detect BMAA. A third method using AQC-derivatized BMAA was also used for comparison. Axenic cultures of Microcystis aeruginosa and Nostoc sp. isolated from Chinese freshwater were analyzed for both free and protein-bound BMAA at the exponential growth stage. Cultures of two strains of M. aeruginosa collected at four growth stages were also analyzed for the presence of BMAA. BMAA was detected in the Nostoc sp. at very low concentrations (<0.07pmoles on column) only when precolumn AQC derivatization was used. No BMAA was detected in the Chinese derived axenic cultures of Microcystis; detection limits for the LC-ESI-MS and LC-ESI-MS/MS without precolumn derivatization were 10ng and 2pg BMAA on column, respectively. We suggest that cyanobacteria grown under some culture conditions may be relatively free of BMAA. PMID:19822166

Li, Aifeng; Tian, Zhijia; Li, Jing; Yu, Rencheng; Banack, Sandra Anne; Wang, Zhenyu

2010-05-01

314

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

PubMed

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

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

2012-09-01

315

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

PubMed Central

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

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

2012-01-01

316

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

317

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

318

Evolution of the freshwater eels.  

PubMed

The freshwater anguillid eels have an unusual life history and world-wide distribution. Questions about the phylogenetic relationships of this group and how their long spawning migrations and larval phase may contribute to their global distribution have not been addressed. This paper is first presentation of molecular phylogeny of Anguilla species, and based on this phylogenetic tree we suggest new aspect of the evolution of this group. Namely, ancestral eels originated during the Eocene or earlier, in the western Pacific Ocean near present-day Indonesia. A group derived from this ancestor dispersed westward, probably by larval transport in the global circum-equatorial current through the northern edge of the Tethys Sea. This group split into the ancestor of the European and American eels, which entered into the Atlantic Ocean, and a second group, which dispersed southward and split into the east African species and Australian species. Thus the world-wide distribution of the eel family can be understood from knowledge of continental drift, ocean currents, a specialized larva and evolutionary forces favoring dispersal and speciation of segregated gene pool. PMID:9050003

Aoyama, J; Tsukamoto, K

1997-01-01

319

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

320

An evaluation of different methods for transportation of the freshwater mussel Lamellidens corrianus (Lea 1834)  

Microsoft Academic Search

The freshwater mussel Lamellidens corrianus (Lea 1834) is widely distributed in ponds and large bodies of perennial waters in the Indian subcontinent. It is one of the\\u000a important species for producing freshwater pearls in India. As the freshwater pearl aquaculture activity may expand on wide\\u000a scale in future, it may require collecting L. corrianus from the distant places and transport

S. I. Yusufzai; H. Singh; M. M. Shirdhankar

2010-01-01

321

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.

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

2011-01-01

322

Investigating dissolved air flotation performance with cyanobacterial cells and filaments  

Microsoft Academic Search

Dissolved air flotation (DAF) performance with two different naturally occurring cyanobacterial morphologies was investigated with respect to the biomass removal efficiency, the toxin release to water and the coagulant demand by different water background natural organic matter (NOM). Coagulation (C)\\/Flocculation (F)\\/DAF bench-scale experiments (2 min coagulation at 380 s?1 with polyaluminium chloride (0.5–4 mg\\/L Al2O3, the dose depending on the water NOM content);

Margarida Ribau Teixeira; Vânia Sousa; Maria João Rosa

2010-01-01

323

Molecular Characterization of an Oil-Degrading Cyanobacterial Consortium  

Microsoft Academic Search

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

Olga Sánchez; Elia Diestra; Isabel Esteve; Jordi Mas

2005-01-01

324

Molecular characterization of cyanobacterial diversity in Lake Gregory, Sri Lanka  

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

325

Sample amount alternatives for data adjustment in comparative cyanobacterial metabolomics  

Microsoft Academic Search

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

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

2011-01-01

326

The Fossil Record: Tracing the Roots of the Cyanobacterial Lineage  

Microsoft Academic Search

Since the mid-1960s, following a century of unrewarded search, impressive progress has been made toward deciphering the Precambrian\\u000a fossil record, evidence of life extant during the earliest seven-eighths of geologic time. Hundreds of fossiliferous units\\u000a have been discovered containing thousands of microbial fossils—dominantly but not exclusively cyanobacterial — and the documented\\u000a antiquity of life has been extended to an age

J. Schopf

327

Monitoring Survival and Preservation of Recent Cyanobacterial Mats  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

328

Classification trees as a tool for predicting cyanobacterial blooms  

Microsoft Academic Search

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

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

329

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

330

Chlorophyll Fluorescence Analysis of Cyanobacterial Photosynthesis and Acclimation  

PubMed Central

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

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

1998-01-01

331

Cyanobacterial-based approaches to improving photosynthesis in plants.  

PubMed

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

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

2013-01-01

332

Mechanics and resonance of the cyanobacterial circadian oscillator.  

PubMed

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

Karafyllidis, Ioannis G

2012-08-01

333

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

334

Cyanobacterial carboxysomes: microcompartments that facilitate CO2 fixation.  

PubMed

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

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

2013-01-01

335

Luminescence properties of a nanoporous freshwater diatom.  

PubMed

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

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

2012-01-01

336

Oceanic spawning ecology of freshwater eels in the western North Pacific  

Microsoft Academic Search

The natural reproductive ecology of freshwater eels remained a mystery even after some of their offshore spawning areas were discovered approximately 100 years ago. In this study, we investigate the spawning ecology of freshwater eels for the first time using collections of eggs, larvae and spawning-condition adults of two species in their shared spawning area in the Pacific. Ovaries of

Katsumi Tsukamoto; Seinen Chow; Tsuguo Otake; Hiroaki Kurogi; Noritaka Mochioka; Michael J. Miller; Jun Aoyama; Shingo Kimura; Shun Watanabe; Tatsuki Yoshinaga; Akira Shinoda; Mari Kuroki; Machiko Oya; Tomowo Watanabe; Kazuhiro Hata; Shigeho Ijiri; Yukinori Kazeto; Kazuharu Nomura; Hideki Tanaka

2011-01-01

337

Serum Electrolyte and Nonelectrolyte Status in Freshwater Juvenile Persian Sturgeon Acipenser persicus  

Microsoft Academic Search

Status of serum electrolyte and nonelectrolyte variables can be used for managing sturgeon species cultured in freshwater or living in seawater. The aim of the present study was to evaluate serum biochemical variables in clinically healthy juvenile Persian sturgeon Acipenser persicus cultured in freshwater. Serum samples from 11 females and 10 males were analyzed, and levels (mean ± SD) of

Farzad Asadi; Ali Hallajian; Ali Shahriari; Peyman Asadian; Malihe Pourkabir

2010-01-01

338

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

339

A Novel Cyanophage with a Cyanobacterial Nonbleaching Protein A Gene in the Genome  

PubMed Central

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

Gao, E-Bin; Gui, Jian-Fang

2012-01-01

340

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

PubMed

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

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

2012-01-01

341

Physiological and antioxidant responses of Medicago sativa-rhizobia symbiosis to cyanobacterial toxins (Microcystins) exposure.  

PubMed

Toxic cyanobacteria in freshwaters can induce potent harmful effects on growth and development of plants irrigated with contaminated water. In this study, the effect of cyanobacteria extract containing Microcystins (MC) on Medicago sativa-rhizobia symbiosis was investigated in order to explore plants response through biomass production, photosynthetic pigment and antioxidant enzymes analysis: Peroxidase (POD), Polyphenoloxidase (PPO) and Catalase (CAT). Alfalfa plants were inoculated with two endosymbiotic rhizobial strains: RhOL1 (MC less sensitive strain) and RhOL3 (MC more sensitive strain), to evaluate the rhizobial contribution on the plant response cultured under cyanobacterial toxins stress. The two rhizobia strains were identified as Ensifer meliloti by sequence analysis of their rrs and atpD genes. The chronic exposure to MC extract showed shoot, root and nodules dry weight decrease, in both symbiosis cultures. The rate of decline in plants inoculated with RhOL3 was higher than that in symbiosis with RhOL1 mainly at 20 ?g L(-1) of MC. Cyanotoxins also reduced photosynthetic pigment content and generated an oxidative stress observed at cellular level. POD, PPO and CAT activities were significantly increased in leaves, roots and nodules of alfalfa plants exposed to MC. These enzyme activities were higher in plants inoculated with RhOL3 especially when alfalfa plants were exposed to 20 ?g L(-1) of MC. The present paper reports new scientific finding related to the behavior of rhizobia-M. sativa associations to MC (Microcystins) for later recommendation concerning the possible use of these symbiosis face to crops exposure to MC contaminated water irrigation. PMID:24125659

El Khalloufi, Fatima; Oufdou, Khalid; Lahrouni, Majida; Faghire, Mustapha; Peix, Alvaro; Ramírez-Bahena, Martha Helena; Vasconcelos, Vitor; Oudra, Brahim

2013-12-15

342

Remote sensing of the cyanobacterial pigment phycocyanin in turbid inland water  

Microsoft Academic Search

The pigment phycocyanin (PC) is a marker for cyanobacterial presence in eutrophic inland water. We present a reflectance band–ratio algorithm for retrieval of cyanobacterial PC. The model conforms to the band settings of the Medium Resolution Imaging Spectrometer. The parameters of the algorithm were optimized using reflectance and absorption data from two highly eutrophic lakes. Using measured specific absorption coefficients

Stefan G. H. Simis; Steef W. M. Peters; Herman J. Gons

2005-01-01

343

Cyanobacterial contribution to the genomes of the plastid-lacking protists  

Microsoft Academic Search

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

Shinichiro Maruyama; Motomichi Matsuzaki; Kazuharu Misawa; Hisayoshi Nozaki

2009-01-01

344

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

National Technical Information Service (NTIS)

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.

H. O. Smith P. C. Maness Q. Xu

2007-01-01

345

Alternative life-history styles of Japanese freshwater sculpins revisited  

Microsoft Academic Search

Japanese freshwater sculpins consist of 6Cottus and 1Trachidermus species, with various types of life-cycles, namely, catadromous, amphidromous, lacustrine land-locked and fluvial land-locked. Among them,C. amblystomopsis andC. nozawae have been regarded as sibling species. Because of very similar morphological and ecological adult characteristics they were formerly classified as a single species.C. amblystomopsis mainly inhabits the lower courses of rivers and produces

Akira Goto

1990-01-01

346

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

347

Thiols in a Connecticut Stratified Freshwater Lake  

NASA Astrophysics Data System (ADS)

Thiols are an important class of dissolved reduced sulfur (DRS) species in aquatic environments. They are generally formed from biological processes or during diagenesis of biogenic matter. Thiols can affect the biogeochemistry of B-type metals as they form strong complexes that influence trace metal speciation, bioavailability and toxicity. While current literature focuses on the biogeochemistry of thiols in marine systems, little is known about the biogeochemistry of thiols in oxic freshwaters. We chose to study thiols in Linsley Pond a stratified freshwater lake that has been extensively studied by Hutchinson. Our goals were to identify and quantify the range of thiols present throughout this small lake. Additionally, we hoped to discern the environmental factors that influence the production and distribution of thiols in the water column, and to evaluate importance of thiols in trace metal speciation. To identify and quantify various thiols in freshwaters, we adopted a sensitive and selective analytical method, which involves precolumn fluorometric labeling coupled to high performance liquid chromatography and sensitive fluorescence detection. Using this method, our analytical detection limit is below one nanomolar. Among others, two thiol species were observed in Linsley Pond: 3-mercaptopropionic acid (3-MPA) and glutathione (GSH). 3-MPA exists in both oxic and anoxic water layers at nanomolar levels, and increases from surface to bottom. GSH is only detected in subsurface layer and co-varies with Chl a, indicating possible biological sources of GSH in these layers. There is a third, unidentified thiol species which is currently under investigation. The unidentified thiol species appears only in anoxic lake waters, and tests indicate that it is not PC2 (phytochelatin with 2 glutamic acid-cysteine units). Throughout the water column, concentrations of all three thiols are greater in whole water samples than in the dissolved phase (0.45 um).

Hu, H.; Mylon, S. E.; Benoit, G.

2003-12-01

348

Global ocean freshwater transport pathways  

NASA Astrophysics Data System (ADS)

Variations in the atmospheric hydrological cycle are most easily observed through ocean salinity changes, and therefore it is useful to understand the basic ocean circulations responsible for maintaining the mean ocean salinity distribution. Ocean freshwater transports are calculated here from geostrophic and Ekman velocities and salinities. The net transports are assigned quantitatively to upper ocean gyre circulations, intermediate and deep overturning, and Bering Strait/Indonesian Throughflow. Excess freshwater input into the ocean in high latitudes must be transported via ocean circulation to the evaporative lower latitudes. High latitude northern hemisphere freshwater input of about 0.6 Sv is removed southwards through deep and intermediate water formation (NADW and NPIW). In complete contrast, high latitude southern hemisphere freshwater, also about 0.6 Sv, is removed northwards via the Atlantic, Pacific and Indian gyres, rather than through deep water formation. This northern-southern hemisphere asymmetry is consistent with the known "Drake Passage" effect. Excess evaporation in the Atlantic and Indian Oceans is balanced by inflow of freshwater from other regions; each transfer is quantified here. The Pacific Ocean is nearly neutral with respect to freshwater. It is seen that the NADW freshwater balance is nearly closed within the Atlantic/Arctic Ocean and the freshwater transport associated with export of NADW to the Southern Ocean is only a small component of the Atlantic freshwater budget. Bering Strait's small freshwater transport of < 0.1 Sv helps to maintain the Atlantic-Pacific salinity difference. However, proportionally large variations in the small Bering Strait transport can only marginally impact NADW salinity, whose freshening relative to saline surface water is mainly due to air-sea/runoff fluxes in the subpolar North Atlantic and Arctic. In contrast, Bering Strait freshwater export has proportionally much greater impact on North Pacific salinity balances, including NPIW salinity, because the Pacific has a much smaller overturning rate than the Atlantic.

Talley, L.

2008-12-01

349

Ecology and taxonomy of a tree-living freshwater crab (Brachyura: Potamoidea: Potamonautidae) from Kenya and Tanzania, East Africa  

Microsoft Academic Search

The ecology and taxonomy of an interesting species of tree-living freshwater crab from the East Usambara mountains, Tanzania, and from the Shimba Hills, Kenya, East Africa is described. This phytotelmic decapod crustacean belongs to a new species of potamonautid freshwater crab in the genus Potamonautes MacLeay, 1838, which is described. This is one of only a few reports of the

Neil Cumberlidge; Marco Vannini

2004-01-01

350

Residual levels of DDTs and PAHs in freshwater and marine fish from Hong Kong markets and their health risk assessment  

Microsoft Academic Search

Axial and ventral muscle from 10 each species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for dichlorodiphenyltrichloroethane (total DDTs including DDE, DDD and DDT) and polycyclic aromatic hydrocarbons (PAHs). Among the 10 freshwater fish species, rice field eel (Monopterus albus) showed significantly higher levels of DDTs in both ventral (125ng\\/g wet wt) and axial

K. C. Cheung; H. M. Leung; K. Y. Kong; M. H. Wong

2007-01-01

351

Transboundary Freshwater Dispute Database  

NSDL National Science Digital Library

The database includes 150 water related treaties and 39 US compacts. The International Treaties and Compacts section is searchable by nation, basin, issues, conflict resolution mechanisms, non-water linkages, and date. US Compacts are searchable by state, basin, focus and date. For all treaties or compacts there is a summary of the agreement, the parties involved, allocations if applicable and other information pertinent to a specific agreement. There is also information available on indigenous approaches to water conflict resolution, a digitized inventory of the world's river basins with data about those basins, and a bibliography featuring publications about transboundary freshwater dispute resolution.

352

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

353

New data on freshwater psammic Gastrotricha from Brazil  

PubMed Central

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

Garraffoni, Andre R. S.; Araujo, Thiago Q.; Lourenco, Anete P.; Balsamo, Maria

2010-01-01

354

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

355

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.

356

Freshwater fishes of Acadia National Park, Mount Desert Island, Maine  

USGS Publications Warehouse

A list of freshwater fishes is presented for Acadia National Park, Mount Desert Island, Maine, based on past survey records, published and unpublished reports, and recent comprehensive surveys within or bordering Park boundaries conducted in 1998 and 1999. Overall, 31 species of fishes have been recorded in freshwaters of the Park or those bordering Park boundaries; 28 of these are still present. Of those, 15 species are likely native to Mount Desert Island, and the indigenous status of one fish species is unknown. The most widely distributed species in lakes and ponds is the golden shiner, Notemigonus crysoleucas Mitchill (83% of ponds), while the most widely-distributed species in brooks is the brook trout, Salvelinus fontinalis Mitchill (56%).

Stone, J.; Le, B. C.; Moring, J. R.

2001-01-01

357

Cryptoendolithic lichen and cyanobacterial communities of the Ross Desert, Antarctica  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

358

Feasting in fresh water: impacts of food concentration on freshwater tolerance and the evolution of food x salinity response during the expansion from saline into fresh water habitats  

PubMed Central

Saline to freshwater invasions have become increasingly common in recent years. A key hypothesis is that rates of freshwater invasions have been amplified in recent years by increased food concentration, yet this hypothesis has remained unexplored. We examined whether elevated food concentration could enhance freshwater tolerance, and whether this effect evolves following saline to freshwater invasions. We examined physiological response to salinity and food concentration in a 2 × 2 factorial design, using ancestral brackish and freshwater invading populations of the copepod Eurytemora affinis. We found that high food concentration significantly increases low-salinity tolerance. This effect was reduced in the freshwater population, indicating evolution following the freshwater invasion. Thus, ample food could enable freshwater invasions, allowing subsequent evolution of low-salinity tolerance even under food-poor conditions. We also compared effects of food concentration on freshwater survival between two brackish populations from the native range. Impacts of food concentration on freshwater survival differed between the brackish populations, suggesting variation in functional properties affecting their propensity to invade freshwater habitats. The key implication is that high food concentration could profoundly extend range expansions of brackishwater species into freshwater habitats, potentially allowing for condition-specific competition between saline invaders and resident freshwater species.

Lee, Carol Eunmi; Moss, Wynne E; Olson, Nora; Chau, Kevin Fongching; Chang, Yu-Mei; Johnson, Kelsey E

2013-01-01

359

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

360

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

361

Effects of Severe Drought on Freshwater Mussel Assemblages  

Microsoft Academic Search

We examined changes in freshwater mussel abundance and species composition at eight sites in Alabama and Mississippi in response to a severe drought in 2000. Five small-stream sites in Bankhead National Forest were heavily impacted by drought; one site dried almost completely, and four sites experienced total or near cessation of flow but retained water in their channels to a

Wendell R. Haag; Melvin L. Warren Jr

2008-01-01

362

Early stages of biofilm succession in a lentic freshwater environment  

Microsoft Academic Search

Initial events of biofilms development and succession were studied in a freshwater environment at Kalpakkam, East Coast of India. Biofilms were developed by suspending Perspex (Plexiglass) panels for 15 days at bimonthly intervals from January 1996 to January 1997. Changes in biofilm thickness, biomass, algal density, chlorophyll a concentration and species composition were monitored. The biofilm thickness, biomass, algal density

R. Sekar; V. P. Venugopalan; K. Nandakumar; K. V. K. Nair; V. N. R. Rao

2004-01-01

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 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 ...

365

Toxin mixture in cyanobacterial blooms--a critical comparison of reality with current procedures employed in human health risk assessment.  

PubMed

Cyanobacteria are the oldest life forms on earth known to produce a broad spectrum of secondary metabolites. The functions/advantages of most of these secondary metabolites (peptides and alkaloids) are unknown, however, some of them have adverse effects in humans and wildlife, especially when ingested, inhaled or upon dermal exposure. Surprisingly, some of these cyanobacteria are ingested voluntarily. Indeed, for centuries mankind has used cyanobacteria as a protein source, primarily Spirulina species. However, recently also Aphanizomenon flos-aquae are used for the production of so called blue green algae supplements (BGAS), supposedly efficacious for treatment of various diseases and afflictions. Unfortunately, traces of neurotoxins and protein phosphatases (inhibiting compounds) have been detected in BGAS, making these health supplements a good example for human exposure to a mixture of cyanobacterial toxins in a complex matrix. The discussion of this and other possible exposure scenarios, e.g. drinking water, contact during recreational activity, or consumption of contaminated food, can provide insight into the question of whether or not our current risk assessment schemes for cyanobacterial blooms and the toxins contained therein suffice for protection of human health. PMID:18461795

Dietrich, Daniel R; Fischer, A; Michel, C; Hoeger, S J

2008-01-01

366

Cyanobacterial contribution to the genomes of the plastid-lacking protists  

PubMed Central

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

2009-01-01

367

2-Methylhopanoids as biomarkers for cyanobacterial oxygenic photosynthesis.  

PubMed

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 3,465 Myr 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 record is sufficiently well preserved. Here we show that 2-methyl-bacteriohopanepolyols 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 2,500 Myr. 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. PMID:10448856

Summons, R E; Jahnke, L L; Hope, J M; Logan, G A

1999-08-01

368

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

369

Molecular insights into the terminal energy acceptor in cyanobacterial phycobilisome.  

PubMed

The linker protein L(CM) (ApcE) is postulated as the major component of the phycobilisome terminal energy acceptor (TEA) transferring excitation energy from the phycobilisome to photosystem II. L(CM) is the only phycobilin-attached linker protein in the cyanobacterial phycobilisome through auto-chromophorylation. However, the underlying mechanism for the auto-chromophorylation of L(CM) and the detailed molecular architecture of TEA is still unclear. Here, we demonstrate that the N-terminal phycobiliprotein-like domain of L(CM) (Pfam00502, LP502) can specifically recognize phycocyanobilin (PCB) by itself. Biochemical assays indicated that PCB binds into the same pocket in LP502 as that in the allophycocyanin ?-subunit and that Ser152 and Asp155 play a vital role in LP502 auto-chromophorylation. By carefully conducting computational simulations, we arrived at a rational model of the PCB-LP502 complex structure that was supported by extensive mutational studies. In the PCB-LP502 complex, PCB binds into a deep pocket of LP502 with a distorted conformation, and Ser152 and Asp155 form several hydrogen bonds to PCB fixing the PCB Ring A and Ring D. Finally, based on our results, the dipoles and dipole-dipole interactions in TEA are analysed and a molecular structure for TEA is proposed, which gives new insights into the energy transformation mechanism of cyanobacterial phycobilisome. PMID:22758351

Gao, Xiang; Wei, Tian-Di; Zhang, Nan; Xie, Bin-Bin; Su, Hai-Nan; Zhang, Xi-Ying; Chen, Xiu-Lan; Zhou, Bai-Cheng; Wang, Zhi-Xin; Wu, Jia-Wei; Zhang, Yu-Zhong

2012-09-01

370

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

371

Bioremediation of hexavalent chromium by a cyanobacterial mat  

NASA Astrophysics Data System (ADS)

The study comprises the use of cyanobacterial mat (collected from tannery effluent site) to remove hexavalent chromium. This mat was consortium of cyanobacteria/blue-green algae such as Chlorella sp., Phormidium sp. and Oscillatoria sp. The adsorption experiments were carried out in batches using chromium concentrations 2-10, 15-30 and 300 ppm at pH 5.5-6.2. The adsorption started within 15 min; however, 96 % reduction in metal concentration was observed within 210 min. The adsorption phenomenon was confirmed by Fourier transform-infrared spectroscopy and energy dispersive X-ray analysis. This biosorption fitted Freundlich adsorption isotherm very well. It was observed that the best adsorption was at 4 ppm, and at 25 ppm in the chosen concentration ranges. Scanning electron micrograph showed the physiology of mat, indicating sites for metal uptake. The main focus was collection of the cyanobacterial mat from local environments and its chromium removal potential at pH 5.5-6.2.

Shukla, Dhara; Vankar, Padma S.; Srivastava, Sarvesh Kumar

2012-12-01

372

Strong influences of larval diet history on subsequent post-settlement growth in the freshwater mollusc Dreissena polymorpha.  

PubMed Central

A significant seasonal variation in size at settlement has been observed in newly settled larvae of Dreissena polymorpha in Lake Constance. Diet quality, which varies temporally and spatially in freshwater habitats, has been suggested as a significant factor influencing the life history and development of freshwater invertebrates. Accordingly, experiments were conducted with field-collected larvae to test the proposal that diet quality can determine planktonic larval growth rates, size at settlement and subsequent post-metamorphic growth rates. Larvae were fed one of two diets or starved. One diet was composed of cyanobacterial cells, which are deficient in polyunsaturated fatty acids (PUFAs) and the other was a mixed diet rich in PUFAs. Freshly metamorphosed animals from the starvation treatment had a carbon content per individual 70% lower than that of larvae fed the mixed diet. This apparent exhaustion of larval internal reserves resulted in a 50% reduction of the post-metamorphic growth rates. Growth was also reduced in animals previously fed the cyanobacterial diet. Hence, low food quantity or low food quality during the larval stage of D. polymorpha, lead to irreversible effects for post-metamorphic animals and are related to inferior competitive abilities.

Wacker, Alexander; von Elert, Eric

2002-01-01

373

A series of experiments aimed at clarifying the mode of action of barley straw in cyanobacterial growth control.  

PubMed

For over 25 years it has been known that rotting barley straw can be used to prevent the development of blooms of cyanobacteria and algae in freshwater bodies, although its effectiveness can be variable. The mode of action is still not understood, although a number of hypotheses have been suggested, many of which are supported by little or no experimental evidence. Here, we provide the first experimental confirmation that microbial activity is responsible for the release of either the growth inhibitory fraction, or its precursor, from whole straw, after three or more weeks of decomposition. However, a much more rapid release of inhibitory components was achieved by fine chopping of fresh straw. In bioassays of straw activity the choice of both the cyanobacterial test strain and the assay temperature affected the outcome. The inhibitory activity of straw was greater when decomposition was carried out in the presence of UV-supplemented visible light and this activity was reduced in the presence of catalase, implying that straw activity may in part involve hydrogen peroxide. A better understanding of straw decomposition is required to clarify the mode of action of straw and allow the optimisation of its use in the field. PMID:22989994

Iredale, Robert S; McDonald, Adrian T; Adams, David G

2012-11-15

374

Temperature and food interact to influence gamete development in freshwater mussels  

Microsoft Academic Search

Freshwater mussels are one of the most threatened faunas in North America and worldwide, but little research has examined\\u000a factors leading to successful reproduction (gamete development and fertilization success) in these species. We combined field\\u000a and laboratory studies to determine the environmental factors influencing successful reproduction in three closely related\\u000a species of freshwater mussels in a south central U.S. river.

Heather S. Galbraith; Caryn C. Vaughn

2009-01-01

375

Changes in gastropod assemblages in freshwater habitats in the vicinity of Basel (Switzerland) over 87 years  

Microsoft Academic Search

The gastropod fauna in 18 freshwater habitats (streams, rivers and ponds) in the vicinity of Basel, first surveyed in 1906\\/1907, was re-examined in 1994. The freshwater snail fauna changed considerably over 87 years. One species (Aplexa hypnorum) recorded in 1906\\/1907 was not found in 1994, most probably it had become extinct in the period between the two surveys. Ten species

Bruno Baur; Birgit Ringeis

2002-01-01

376

Comparative ecology of submersed grass beds in freshwater, estuarine, and marine environments  

Microsoft Academic Search

Worldwide, there arc 500-700 species of submersed angiosperms adapted to freshwater and estuarine environments compared with 50 species adapted to marine waters. In their evolution from freshwater ancestors, seagrasses have undergone extensive anatomical changes (e.g. reduction in floral and leaf structures, reduction of xylem tissue with a lacuna1 gas transport system), as well as physiological adaptations (bicarbonate utilization in photosynthesis).

J. COURT STEVENSON

1988-01-01

377

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

378

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.

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

2014-01-01

379

Degradation mechanism of cyanobacterial toxin cylindrospermopsin by hydroxyl radicals in homogeneous UV/H?O? process.  

PubMed

The degradation of cylindrospermopsin (CYN), a widely distributed and highly toxic cyanobacterial toxin (cyanotoxin), remains poorly elucidated. In this study, the mechanism of CYN destruction by UV-254 nm/H2O2 advanced oxidation process (AOP) was investigated by mass spectrometry. Various byproducts identified indicated three common reaction pathways: hydroxyl addition (+16 Da), alcoholic oxidation or dehydrogenation (-2 Da), and elimination of sulfate (-80 Da). The initiation of the degradation was observed at the hydroxymethyl uracil and tricyclic guanidine groups; uracil moiety cleavage/fragmentation and further ring-opening of the alkaloid were also noted at an extended reaction time or higher UV fluence. The degradation rates of CYN decreased and less byproducts (species) were detected using natural water matrices; however, CYN was effectively eliminated under extended UV irradiation. This study demonstrates the efficiency of CYN degradation and provides a better understanding of the mechanism of CYN degradation by hydroxyl radical, a reactive oxygen species that can be generated by most AOPs and is present in natural water environment. PMID:24625255

He, Xuexiang; Zhang, Geshan; de la Cruz, Armah A; O'Shea, Kevin E; Dionysiou, Dionysios D

2014-04-15

380

Halophytophthora fluviatilis sp. nov. from freshwater in Virginia.  

PubMed

Halophytophthora fluviatilis, a novel species from inland freshwater in Virginia, is characterized and described in this study. This homothallic species produced ovoid to globose sporangia, which release zoospores directly through exit pores. It grew well in a relatively wide range of salinity from 1.8 to 19.0 parts per thousand. Sequence analysis of the rRNA internal transcribed spacer region placed this new species in the Halophytophthora sensu stricto clade. Description of this new species expanded the habitat to include geographically distinct inland freshwater ecosystems for the genus Halophytophthora, challenging the notion that this genus is marine or brackish. The need to construct a molecular-based taxonomy for the genus Halophytophthora is also discussed. PMID:24484074

Yang, Xiao; Hong, Chuanxue

2014-03-01

381

Biomarkers of Type II Synthetic Pyrethroid Pesticides in Freshwater Fish  

PubMed Central

Type II synthetic pyrethroids contain an alpha-cyano group which renders them more neurotoxic than their noncyano type I counterparts. A wide array of biomarkers have been employed to delineate the toxic responses of freshwater fish to various type II synthetic pyrethroids. These include hematological, enzymatic, cytological, genetic, omic and other types of biomarkers. This review puts together the applications of different biomarkers in freshwater fish species in response to the toxicity of the major type II pyrethroid pesticides and assesses their present status, while speculating on the possible future directions.

2014-01-01

382

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

383

Aggressive interactions during feeding between native and invasive freshwater turtles  

Microsoft Academic Search

The red-eared slider (Trachemys scripta elegans) is a worldwide highly invasive species, currently introduced in most freshwater habitats as a consequence of massive pet\\u000a trade. In the Iberian Peninsula, this species is competing with and displacing the endangered native Spanish terrapin (Mauremys leprosa). Sliders are considered environmentally-aggressive turtles, capable of threatening or biting other individuals during competitive\\u000a activities such as

Nuria Polo-CaviaPilar; Pilar López; José Martín

2011-01-01

384

Production and consumption of methane in freshwater lake ecosystems.  

PubMed

The atmospheric concentration of methane (CH(4)), a major greenhouse gas, is mainly controlled by the activities of methane-producing (methanogens) and methane-consuming (methanotrophs) microorganisms. Freshwater lakes are identified as one of the main CH(4) sources, as it was estimated that they contribute to 6-16% of natural CH(4) emissions. It is therefore critical to better understanding the biogeochemical cycling of CH(4) in these ecosystems. In this paper, the effects of environmental factors on methanogenic and methanotrophic rates are reviewed and an inventory of the methanogens and methanotrophs at the genus/species level in freshwater lakes is given. We focus on the anaerobic oxidation of methane, which is a still poorly known process but increasingly reported in freshwater lakes. PMID:21704700

Borrel, Guillaume; Jézéquel, Didier; Biderre-Petit, Corinne; Morel-Desrosiers, Nicole; Morel, Jean-Pierre; Peyret, Pierre; Fonty, Gérard; Lehours, Anne-Catherine

2011-11-01

385

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

386

Phylogenetic diversity of a microbialite reef in a cold alkaline freshwater lake.  

PubMed

A culture-independent multidomain survey of biodiversity in microbialite structures within the cold alkaline Pavilion Lake (British Columbia, Canada) revealed a largely homogenous community at depths from 10 to 30 m. Real-time quantitative PCR was used to demonstrate that bacteria comprised approximately 80%-95% of recoverable phylotypes. Archaeal phylotypes accounted for <5% of the community in microbialites exposed to the water column, while structures in sediment contact supported 4- to 5-fold higher archaeal abundance. Eukaryal phylotypes were rare and indicated common aquatic diatoms that were concluded not to be part of the microbialite community. Phylogenetic analysis of rRNA genes from clone libraries (N = 491) revealed that alphaproteobacterial phylotypes were most abundant. Cyanobacterial phylotypes were highly diverse but resolved into 4 dominant genera: Acaryochloris, Leptolyngbya, Microcoleus, and Pseudanabaena. Interestingly, microbialite cyanobacteria generally affiliated phylogenetically with aquatic and coral cyanobacterial groups rather than those from stromatolites. Other commonly encountered bacterial phylotypes were from members of the Acidobacteria, with relatively low abundance of the Betaproteobacteria, Chloroflexi, Nitrospirae, and Planctomycetes. Archaeal diversity (N = 53) was largely accounted for by Euryarchaeota, with most phylotypes affiliated with freshwater methanogenic taxa. PMID:24861562

Chan, Olivia W; Bugler-Lacap, Donnabella C; Biddle, Jennifer F; Lim, Darlene S; McKay, Christopher P; Pointing, Stephen B

2014-06-01

387

Cyanobacterial calcification in modern microbialites at the submicrometer-scale  

NASA Astrophysics Data System (ADS)

The search for microfossils in the geological record has been a long-term challenge. Part of the problem comes from the difficulty of identifying such microfossils unambiguously, since they can be morphologically confused with abiotic biomorphs. One route to improve our ability to correctly identify microfossils consists in studying fossilization processes affecting bacteria in modern settings. We studied the initial stages of fossilization of cyanobacterial cells in modern microbialites from Lake Alchichica (Mexico), a Mg-rich hyperalkaline crater lake (pH 8.9) hosting currently growing stromatolites composed of aragonite [CaCO3] and hydromagnesite [Mg5(CO3)4(OH)2 × 4(H2O)]. Most of the biomass associated with the microbialites is composed of cyanobacteria. Scanning electron microscopy analyses coupled with confocal laser scanning microscopy observations were conducted to co-localize cyanobacterial cells and associated minerals. These observations showed that cyanobacterial cells affiliating to the order Pleurocapsales become specifically encrusted within aragonite with an apparent preservation of cell morphology. Encrustation gradients from non-encrusted to totally encrusted cells spanning distances of a few hundred micrometers were observed. Cells exhibiting increased levels of encrustation along this gradient were studied down to the nm-scale using a combination of focused ion beam (FIB) milling, transmission electron microscopy (TEM) and scanning transmission X-ray microscopy (STXM) at the C, O and N K-edges. Two different types of aragonite crystals were observed: one type was composed of needle-shaped nano-crystals growing outward from the cell body with a crystallographic orientation perpendicular to the cell wall, and another type was composed of larger crystals that progressively filled the cell interior. Organic matter (OM), initially co-localized with the cell, decreased in concentration and dispersed away from the cell while crystal growth occurred. As encrustation developed, OM progressively disappeared, but remaining OM showed the same spectroscopic signature. In the most advanced stages of fossilization, only the textural organization of the two types of aragonite recorded the initial cell morphology and spatial distribution.

Couradeau, E.; Benzerara, K.; Gérard, E.; Estève, I.; Moreira, D.; Tavera, R.; López-García, P.

2013-02-01

388

THE TRPV1 RECEPTOR: THE INTERAGENCY, INTERNATION SYMPOSIUM ON CYANOBACTERIAL HARMFUL ALGAL BLOOMS.  

EPA Science Inventory

Background and Significance Evidence indicates that the frequency of occurrence of cyanobacterial harmful algal blooms (CHABs) is increasing in spatial and temporal extent in the US and worldwide. Cyanotoxins are among the most potent toxins known, causing death through ...

389

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...

390

Antibacterial, antifungal and cytotoxic activity of terrestrial cyanobacterial strains from Serbia  

Microsoft Academic Search

Cyanobacteria are known to be a rich source of biologically active compounds some of which can have pharmaceutical importance.\\u000a In this work we present the screening results of cyanobacterial strains for their antibacterial, antifungal, and cytotoxic\\u000a activity. Cyanobacterial strains were isolated from various soil types in province of Vojvodina and Central Serbia, Republic\\u000a of Serbia. The screening included 9 strains

Zorica Svircev; Dragana Cetojevic-Simin; Jelica Simeunovic; Maja Karaman; Dejan Stojanovic

2008-01-01

391

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

392

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

393

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

394

A salinity and sulfate manipulation of hypersaline microbial mats reveals stasis in the cyanobacterial community structure.  

PubMed

The cyanobacterial community structure and composition of hypersaline mats were characterized in an experiment in which native salinity and sulfate levels were modified. Over the course of approximately 1 year, microbial mats collected from Guerrero Negro (Baja, California Sur, Mexico) were equilibrated to lowered salinity (to 35 p.p.t.) and lowered sulfate (below 1 mM) conditions. The structure and composition of the cyanobacterial community in the top 5 mm of these mats were examined using a multifaceted cultivation-independent molecular approach. Overall, the relative abundance of cyanobacteria-roughly 20% of the total bacterial community, as assayed with a PCR-based methodology-was not significantly affected by these manipulations. Furthermore, the mat cyanobacterial community was only modestly influenced by the dramatic changes in sulfate and salinity, and the dominant cyanobacteria were unaffected. Community composition analyses confirmed the dominant presence of the cosmopolitan cyanobacterium Microcoleus chthonoplastes, but also revealed the dominance of another Oscillatorian cyanobacterial group, also detected in other hypersaline microbial mats. Cyanobacterial populations increasing in relative abundance under the modified salinity and sulfate conditions were found to be most closely related to other hypersaline microbial mat organisms, suggesting that the development of these mats under native conditions precludes the development of organisms better suited to the less restrictive experimental conditions. These results also indicate that within a significant range of salinity and sulfate concentrations, the cyanobacterial community is remarkably stable. PMID:18288215

Green, Stefan J; Blackford, Cameron; Bucki, Patricia; Jahnke, Linda L; Prufert-Bebout, Lee

2008-05-01

395

Homogenization patterns of the world's freshwater fish faunas  

PubMed Central

The world is currently undergoing an unprecedented decline in biodiversity, which is mainly attributable to human activities. For instance, nonnative species introduction, combined with the extirpation of native species, affects biodiversity patterns, notably by increasing the similarity among species assemblages. This biodiversity change, called taxonomic homogenization, has rarely been assessed at the world scale. Here, we fill this gap by assessing the current homogenization status of one of the most diverse vertebrate groups (i.e., freshwater fishes) at global and regional scales. We demonstrate that current homogenization of the freshwater fish faunas is still low at the world scale (0.5%) but reaches substantial levels (up to 10%) in some highly invaded river basins from the Nearctic and Palearctic realms. In these realms experiencing high changes, nonnative species introductions rather than native species extirpations drive taxonomic homogenization. Our results suggest that the “Homogocene era” is not yet the case for freshwater fish fauna at the worldwide scale. However, the distressingly high level of homogenization noted for some biogeographical realms stresses the need for further understanding of the ecological consequences of homogenization processes.

Villeger, Sebastien; Blanchet, Simon; Beauchard, Olivier; Oberdorff, Thierry; Brosse, Sebastien

2011-01-01

396

The cyanobacterial neurotoxin ?-N-methylamino-l-alanine (BMAA) induces neuronal and behavioral changes in honeybees.  

PubMed

The cyanobacterially produced neurotoxin beta-N-methylamino-l-alanine (BMAA) is thought to induce amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC)-like symptoms. However, its mechanism of action and its pathway of intoxication are yet unknown. In vivo animal models suitable for investigating the neurotoxic effect of BMAA with applicability to the human are scarce. Hence, we used the honeybee (Apis mellifera) since its nervous system is relatively simple, yet having cognitive capabilities. Bees fed with BMAA-spiked sugar water had an increased mortality rate and a reduced ability to learn odors in a classical conditioning paradigm. Using (14)C-BMAA we demonstrated that BMAA is biologically available to the bee, and is found in the head, thorax and abdomen with little to no excretion. BMAA is also transferred from one bee to the next via trophallaxis resulting in an exposure of the whole beehive. BMAA bath application directly onto the brain leads to an altered Ca(2+) homeostasis and to generation of reactive oxygen species. These behavioral and physiological observations suggest that BMAA may have effects on bee brains similar to those assumed to occur in humans. Therefore the bee could serve as a surrogate model system for investigating the neurological effects of BMAA. PMID:23591064

Okle, Oliver; Rath, Lisa; Galizia, C Giovanni; Dietrich, Daniel R

2013-07-01

397

Carbon and Oxygen Budgets of Hypersaline Cyanobacterial Mats: Effects of Tidal Cycle and Temperature  

NASA Technical Reports Server (NTRS)

The hierarchical organization of microbial ecosystems determines the rates of processes that shape Earth#s environment, define the stage upon which major evolutionary events occurred, and create biosignatures in sediments and atmospheres. In cyanobacterial mats, oxygenic photosynthesis provides energy, organic substrates and oxygen to the ecosystem. Incident light changes with depth in the mat, both in intensity and spectral composition, and counteracting gradients of oxygen and sulfide shape the chemical microenvironment. A 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. Microbiota produce hydrogen, small organic acids, and nitrogen and sulfur species. Such compounds fuel a flow of energy and electrons in these ecosystems and thus shape interactions between groups of microorganisms. Coordinated observations of population distribution, abundance, and activity for an entire community are making fundamental questions in ecology accessible. These questions address those factors that sustain the remarkable diversity of microorganisms that are now being revealed by molecular techniques. These questions also target the processes that shape the various kinds of biosignatures that we will seek, both in ancient rocks from Earth and Mars, and in atmospheres of distant planets beyond our Solar System.

DesMarais, David J.; Bebout, Brad M.; Carpenter, Steven; Discipulo, Mykell; Turk, Kendra

2003-01-01

398

Enzymatic pathway for the bacterial degradation of the cyanobacterial cyclic peptide toxin microcystin LR.  

PubMed Central

An isolated bacterium, identified as a new Sphingomonas species, was demonstrated to contain a novel enzymatic pathway which acted on microcystin LR, the most common cyanobacterial cyclic peptide toxin. Degradation of microcystin LR was mediated by at least three intracellular hydrolytic enzymes. The use of classic protease inhibitors allowed (i) the classification of these enzymes into general protease families and (ii) the in vitro accumulation of otherwise transient microcystin LR degradation products. The initial site of hydrolytic cleavage of the parent cyclic peptide by an enzyme that we designate microcystinase is at the 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda)-Arg peptide bond. Two intermediates of microcystin LR enzymatic degradation have been identified; one is linearized (acyclo-) microcystin LR, NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-Leu-beta-methylas partate-Arg-OH, and the other is the tetrapeptide NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-OH. The intermediate degradation products were less active than the parent cyclic peptide; the observed 50% inhibitory concentrations for crude chicken brain protein phosphatase were 0.6 nM for microcystin LR, 95 nM for linear LR, and 12 nM for the tetrapeptide. These linear peptides were nontoxic to mice at doses up to 250 micrograms/kg. Ring opening of the potent hepatotoxin microcystin LR by bacterial microcystinase effectively renders the compound nontoxic by dramatically reducing the interaction with the target protein phosphatase.

Bourne, D G; Jones, G J; Blakeley, R L; Jones, A; Negri, A P; Riddles, P

1996-01-01

399

Fluorescence from Pearls of Freshwater Bivalves and Its Contribution to the Distinction of Mother Oysters Used in Pearl Culture  

NASA Astrophysics Data System (ADS)

By measuring the fluorescence spectra of pearls from various species of mother oysters, a distinction has already become possible as to whether the pearls are from Pinctada fucata, Pinctada maxima, Pteria penguin or Pinctada margaritifera. In this study, the fluorescence of pearls from freshwater bivalves was measured. The results have made it possible to distinguish freshwater pearls from the other pearls mentioned above.

Miyoshi, Tadaki; Matsuda, Yasunori; Akamatsu, Shigeru

1988-01-01

400

What do tadpoles really eat? Assessing the trophic status of an understudied and imperiled group of consumers in freshwater habitats  

Microsoft Academic Search

SUMMARY 1. Understanding the trophic status of consumers in freshwater habitats is central to understanding their ecological roles and significance. Tadpoles are a diverse and abundant component of many freshwater habitats, yet we know relatively little about their feeding ecology and true trophic status compared with many other consumer groups. While many tadpole species are labelled herbivores or detritivores, there

RONALD A LTIG; M ATT R. W HILES; INDY L. T AYLOR