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To increase the knowledge on diversity of freshwater cyanobacteria, we have characterized a novel filamentous, benthic cyanobacterium isolated from a pond in Golestan province, Iran. The isolate was studied using a polyphasic approach based on morphological and molecular characteristics, including phylogenetic and structural analysis of the 16S rRNA gene sequence and 16S to 23S internal transcribed spacer (ITS), respectively. The overall morphology of the isolate was similar to Nostocalean member's strains with non-tapering filaments and distributed heterocytes. However, the molecular analyses suggested that it was more closely related to the lithobiont and rock-dwelling Goleter apudmare Miscoe & J.R.Johansen, which has tapered filaments and basal heterocytes. The 16S rRNA gene phylogenetic analysis, based on bayesian inference and maximum likelihood methods, placed the isolate close to G. apudmare. The D1-D1', Box-B and V3 helixes of the isolate's ITS sequence were different when compared to other Goleter ITS sequences. Similar to G. apudmare HA4356-MV2 (JN385288.1) and Goleter sp. CHAB TP201702 (MT488126.1), tRNA genes were absent from the amplified ITS sequence in the studied isolate. These morphological and molecular characteristics differentiate this isolate from all other Goleter taxa described so far, which contributes to extend the knowledge on cyanobacterial diversity and occurrence of benthic cyanobacteria in Iranian freshwaters. Caractérisation morphologique et moléculaire de Goleter sp. (Nostocales, Nostocaceae) isolée de l'eau douce en Iran. Pour accroître les connaissances sur la diversité des cyanobactéries d'eau douce, nous avons caractérisé une nouvelle cyanobactérie benthique filamenteuse isolée d'un étang de la province du Golestan, en Iran. L'isolat a été étudié en utilisant une approche polyphasique basée sur les caractéristiques morphologiques et moléculaires, comprenant l'analyse phylogénétique et structurelle de la séquence du gène de l'ARNr 16S et de l'espaceur transcrit interne (ITS) 16S à 23S, respectivement. La morphologie globale de l'isolat était similaire à celle des souches membres des Nostocales avec des filaments non effilés et des hétérocytes distribués. Cependant, les analyses moléculaires suggèrent qu'il était plus étroitement lié au lithobionte et au Goleter apudmare Miscoe & J.R.Johansen vivant dans les roches, qui possède des filaments effilés et des hétérocytes basaux. L'analyse phylogénétique du gène de l'ARNr 16S, basée sur les méthodes d'inférence bayésienne et de vraisemblance maximale, a placé l'isolat à proximité de G. apudmare. Les hélices D1-D1', Box-B et V3 de la séquence ITS de l'isolat étaient différentes par rapport aux autres séquences Goleter ITS. De la même manière que G. apudmare HA4356-MV2 (JN385288.1) et Goleter sp. CHAB TP201702 (MT488126.1), les gènes d'ARNt étaient absents de la séquence ITS amplifiée dans l'isolat étudié. Ces caractéristiques morphologiques et moléculaires différencient cet isolat de tous les autres taxons de Goleter décrits jusqu'à présent, ce qui contribue à étendre les connaissances sur la diversité cyanobactérienne et la présence de cyanobactéries benthiques dans les eaux douces iraniennes. [ABSTRACT FROM AUTHOR]

La pêche à l’électricité est une méthode classiquement utilisée pour les inventaires de biodiversité des poissons et crustacés dans le cadre de la surveillance réglementaire de l’état écologique des cours d’eau. Elle pose un certain nombre de difficultés en territoires ultramarins tropicaux, de par certaines spécificités physiques (conductivité de l’eau basse à très basse) et écologiques (communautés mixtes de poissons et de crustacés, biodiversité forte à très forte) qui les caractérisent. Issues du partenariat OFB-INRAE, les recherches menées en collaboration avec l’entreprise HYDRECO-Guyane ont permis de définir des conditions spécifiques d’application de la pêche à l’électricité pour les petits cours d’eau (< 6 mètres de large) tropicaux. Grâce à des essais au laboratoire et in situ, en Guyane, aux Antilles et à La Réunion, nous avons identifié les réglages électriques les plus efficaces pour la capture, l’estimation de la richesse spécifique et de l’abondance des espèces et le respect de la santé animale. Ces recherches se placent dans l’objectif plus large d’améliorer la qualité des données bancarisées pour le suivi environnemental des masses d’eau. Elles donnent lieu à des recommandations pour la maitrise d’œuvre et la maitrise d’ouvrage de la pêche à l’électricité en petits cours d’eau tropicaux.

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Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The export of shrimp from Benin could develop, but remains almost non-existent due to the non-compliance with sanitary standards required on the international market, which undermines the sustainability of shrimp value chains. This study evaluates the economic performance of freshwater shrimp value chains in Benin. The conceptual and accounting approaches of the value chain were used to identify stakeholders, analyse their business linkages and evaluate the process of creation and reallocation of the wealth along the different value chains. Socio-economic data were collected through an individual survey on a random sample of 204 stakeholders in shrimp value chains, distributed in six communes in Southern Benin. Results display three major value chains based on three differentiated products (fresh, smoked and fried shrimps) where five types of direct stakeholders operate. The value chains accounting profile analysis reveals that the total added value, as well as the profit created by each of the three value chains, are all positive, highlighting that all three are efficient and have comparative advantages. The smoked shrimp value chain is more efficient than the other two, regarding added value and profit. Support actions such as funding, advisory support, and organization of stakeholders, could support the three value chains in order to strengthen the creation of added value in the shrimp sector in Benin. [ABSTRACT FROM AUTHOR]

Copyright of Algerian Journal of Environmental Science & Technology is the property of Algerian Journal of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biodiversity loss is a serious issue for freshwater fishes in temperate climates and there is a need for more information in this area. A study was conducted to assess fish community changes in the littoral zone of 22 lakes over a 45 year period (compared years 1969-1979 and year 2014). To compare fish communities, historical seining records were compiled for 22 inland lakes and compared with contemporary data sampled using the same protocol. Fish abundance data analyzed using a multivariate approach identified a shift from cyprinid-dominated communities to centrarchid-dominated communities between time periods. There was no evidence to support a strong influence of invasive species on these communities, but there have been significant changes in temperature and land use around these lakes since the historical data sets were collected. This is an important contribution to our understanding of biodiversity change in North American freshwater fish communities and may influence fisheries management approaches in the future. [ABSTRACT FROM AUTHOR]

Introduced species influence the dynamics and structure of freshwater systems; understanding the variables that shape introduced species' distributions can aid in anticipating their spread. We examined multiple factors that may influence the distribution of northern crayfish ( Orconectes virilis (Hagen, 1870)), an introduced species, in New Hampshire, USA. Sampling occurred July to August 2010 in 20 lakes. We tested catch per unit effort (CPUE) and body size of crayfish against lake trophic status, size, depth, and shoreline development, as well as substrate type. We also compared CPUE and body size in the presence or absence of known predators, smallmouth bass ( Micropterus dolomieu Lacepède, 1802) and largemouth bass ( Micropterus salmoides (Lacepède, 1802)). Crayfish body size was not strongly associated with any tested variables, nor were there significant correlations between lake-level parameters and CPUE. CPUE increased with rocky substrates and decreased with macrophyte cover. We also found significantly lower CPUE in lakes with bass predators; this could be due to consumptive effects directly lowering crayfish abundance, nonconsumptive effects of bass on crayfish behavior, or both. Our work provides a baseline for future surveys examining northern crayfish or bass expansion in New Hampshire and highlights a variable that could be important as this crayfish colonizes additional locations outside its native range. [ABSTRACT FROM AUTHOR]

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dispersal is one of the key mechanisms affecting the distribution of individuals, populations, and communities in nature. Despite advances in the study of single species, it has been notoriously difficult to account for dispersal in multispecies metacommunities, where it potentially has strong effects on community structure beyond those of local environmental conditions. Dispersal should thus be directly integrated in both basic and applied research by using proxies. Here, we review the use of proxies in the current metacommunity research, suggest new proxies, and discuss how proxies could be used in community modelling, particularly in freshwater systems. We suggest that while traditional proxies may still be useful, proxies formerly utilized in transport geography may provide useful novel insights into the structuring of biological communities in freshwater systems. We also suggest that understanding the utility of such proxies for dispersal in metacommunities is highly important for many applied fields such as freshwater bioassessment, conservation planning, and recolonization research in the context of restoration ecology. These research fields have often ignored spatial dynamics and focused mostly on local environmental conditions and changes therein. Yet, the conclusions of these applied studies may change considerably if dispersal is taken into account. [ABSTRACT FROM AUTHOR]

L’examen de Clarias pachynema Boulenger, 1903 (Clariidae), Ctenopoma petherici Günther, 1864 (Anabantidae) et Parachanna obscura (Günther, 1861) (Channidae), capturés dans le bassin du Nkam au Cameroun, a révélé la présence de deux espèces nouvelles de Myxosporidies du genre Myxidium Bütschli, 1882, toutes parasites de la vésicule biliaire. Les espèces inédites sont : Myxidium nkamensis n. sp., parasite de Clarias pachynema; M. sangei n. sp., qui forme des spores dans la paroi de la vésicule biliaire de Parachanna obscura. Deux autres espèces, Myxidium petrocephali Fomena et Bouix, 1986 et M. distichodi Kostoïngué, Faye et Toguebaye, 1998, ont été retrouvées chez des hôtes nouveaux. Leur diagnose est complétée. La liste des espèces de Myxidium parasites des poissons d’eau douce d’Afrique est donnée.

L’examen de Schilbe mystus (Linné, 1758) (Schilbeidae) et Citharinus citharus (Geoffroy Saint-Hilaire, 1809) (Citharinidae), capturés respectivement dans les bassins de la Sanaga à Edéa et de la Bénoué à Lagdo, a révélé la présence de deux espèces nouvelles de Myxosporidies appartenant au genre Thelohanellus Kudo, 1993 : Thelohanellus njinei n. sp., parasite de l’intestin de Schilbe mystus et Thelohanellus lagdoensis n. sp., parasite de l’intestin chez Citharinus citharus. Des informations complémentaires sont données sur la diagnose de Thelohanellus citharini, parasite antérieurement décrit au Tchad.

Our knowledge of the freshwater cyclopid copepods of the Visayas Islands remains poor as compared to other terrestrial and aquatic fauna. This study focuses on two genera, Mesocyclops and Thermocyclops, which are common components of lake plankton communities. This study included specimens collected from 59 sampling sites found in major islands (Panay, Negros, Cebu, Bohol, Leyte and Samar) and a small island (Pacijan) in the Visayas region. Four species of Mesocyclops and three species of Thermocyclops were identified. This includes the first record of Mesocyclops woutersi in the Philippines, which was so far unknown from insular SE Asia. The endemic Mesocyclops microlasius, previously reported from Luzon Island, was also found in Lake Danao (Pacijan Island). An identification key to Philippine species of Mesocyclops and Thermocyclops is herein provided. Geographic distribution and possible causes of the low number of species observed and their implications for further faunal studies are also discussed. [ABSTRACT FROM AUTHOR]

Temporal responses of indigenous bacterial populations and proteolytic enzyme (i.e., aminopeptidase) activities in the bacterioplankton assemblages from 3 separate freshwater environments were examined after exposure to various zinc (Zn) concentrations under controlled microcosm conditions. Zn concentrations (ranging from 0 to 10 μmol/L) were added to water samples collected from the Kalamazoo River, Rice Creek, and Huron River and examined for bacterial abundance and aminopeptidase activities at various time intervals over a 48 h incubation period in the dark. The results showed that the Zn concentrations did not significantly influence total bacterial counts directly; however, aminopeptidase activities varied significantly to increasing zinc treatments over time. Also, analysis of variance and linear regression analyses revealed significant positive relationships between bacterial numbers and their hydrolytic enzyme activities, suggesting that both probably co-vary with increasing Zn concentrations in aquatic systems. The results from this study serve as additional evidence of the ecological role of Zn as an extracellular peptidase cofactor on the dynamics of bacterial assemblages in aquatic environments. [ABSTRACT FROM AUTHOR]

Les auteurs décrivent chez Schilbe mandibularis (Günther, 1867) (Schilbeidae) des rivières Bia et Agnéby de Côte d'Ivoire une nouvelle espèce de Monogène, parasite branchial, du genre Schilbetrematoides Kritsky & Kulo, 1992. S. manizani n sp. diffère essentiellement de S. pseudodactylogyrus Kritsky & Kulo, 1992 parasite de Schilbe intermedius Ruppell, 1832 par la morphologie très particulière des gripi.

A new ion exchange chromatography method is presented for the isolation of high field-strength elements ( HFSE) from freshwater and seawater samples that have undergone iron coprecipitation. Large volumes of water can be condensed through the application of iron coprecipitation, but clean separation of elements from the precipitate proves difficult. The technique described is a five-column process designed to separate the HFSE, including rare earth elements such as neodymium and hafnium, before removing the iron and isolating uranium. Subsequent isolation of Nd and Hf was achieved using established ion exchange chromatography methods. The efficacy of our chemistry was verified by measurements of analytical reference materials - both reference solutions and seawater samples - subjected to the chemical separation methods described. Elution results indicate high yields (> 90%) determined by concentration measurements of a known reference material added to each column. Measurement results for isotopic compositions of seawater (U, Nd) and reference solutions ( NIST SRM 960, U) were identical within uncertainty to previously published values. Compositions were identical between solutions (Spex CLMS3, Spex PLND2) that underwent different iron coprecipitation procedures. Isotopic determinations for reference materials JNdi-1 and NIST SRM 960 measured with the mass spectrometers used in this study were in agreement with universally accepted values for these materials, and indicate high precision. [ABSTRACT FROM AUTHOR]