مجله بین المللی زیست شناسی آبزیان
سال:1396 | دوره:5 | شماره:2 |تعداد مقالات:7

Estuarine environments are one of the most dynamic aquatic ecosystems and serve manyimportant functions in coastal waters. Larval fish dynamics contribute significantly to understandingthe ecology of fish populations as they can indicate the spawning-stock biomass and recruitment inadult fish stocks. Initial development stages of fishes are particularly vulnerable and are influencedby physical and biological processes. Hence the present study was aimed to characterizeichthyoplankton assemblages, to evaluate environmental influence in its structure. Ponnanibackwater fish larvae assemblages displayed a clear seasonal pattern presenting higher abundancesand diversities during warmer months. Throughout the year there is a wide fluctuation in salinity, temperature and primary productivity in these backwaters enabling it to be classified under stressfulenvironment for larval forms of certain economically important marine fishes. A detailed analysismade to study the interaction of selected environmental parameters with ichthyofaunal diversity inPonnani backwater provided a clear understanding on the influence of these variables on thedistribution of marine fish larvae in the region. The results of the present analysis provided a modelfor the prediction of larval diversity from the prevailing environmental parameters.

This study aims to assess ecosystem diversity of Rotifera of the floodplain lakes (beels)of the Brahmaputra river basin with reference to faunal diversity of the taxon in wetlands ofconservation areas of India. We observed 141 rotifer species, belonging to 31 genera and 17 families, from three beels of the Dibru-Saikhowa Biosphere Reserve (DSBR) of Assam, northeast India (NEI)with high total richness (117±2 species) in individual beels. One, two and three species are new tothe Oriental region, India and Assam state, respectively and 21 species are globally interesting. Thediverse Lecanidae>Lepadellidae>Trichocercidae; the paucity and scarceness of Brachionidae andBrachionus spp. in particular; and rare nature of Keratella, Filinia, Asplanchna, Polyarthra, andConochilus are salient. The monthly richness and community similarities affirmed heterogeneity inspecies composition in individual beels while this study exhibited overall rotifer homogeneityamongst beels. The richness followed monthly oscillations in the three beels and lacked significantvariations amongst beels. The peak richness of 76 species during summer (May, 2014) from No.11beel is one of the richest rotifer assemblages known in single date collection from an aquaticecosystem of South Asia. Our results explained little influence of individual abiotic factors whilecanonical correspondence analysis endorsed high cumulative influence of 17 abiotic factors onrichness in all beels.

Six sampling sites were selected to represent different land use types in the rehabilitatedand non-rehabilitated areas of a recreational wetland in Sri Lanka to study the suitability ofmacrobenthic mollusc diversity to monitor spatial and temporal variation in physico-chemicalparameters of water and shallow sediments. Individuals belonging to six families and eight specieswere recorded during the study. The significantly highest mean abundance (individuals) of Bithyniatentaculata and Pila globosa were recorded in sites from the rehabilitated area and there was nosignificant temporal variation of mollusc abundance during the study. The abundance and diversityof mollusc community showed significant spatial variations and this study identified thatB. tentaculata and P. globosa can be used as possible bioindicators to detect changes in water andshallow sediment quality in tropical wetland ecosystems

Alongside anthropogenic activities and habitat destruction, invasions are regarded as oneof the most influential components of global change. India as a growing economy and rapidlydeveloping nation has been constantly engaged in infrastructure development which consequentlyhas led to depletion of natural resources and declining quality of habitats aquatic systems inparticular. Invasions that have established from the introductions in past during the colonial era andrecently spread species are great challenges that hamper survival of aquatic resources. As of 2015, 20 plants, one mollusc and 38 fishes are known to have naturalized in the Indian water bodies.Awareness on the invasive species along with detailed information on the ecosystem-wide impactsis essential for management.