INTERNATIONAL JOURNAL OF AQUATIC BIOLOGY
Year:2017 | Volume:5 | Issue:2 |Papers Count:7

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.

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.

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 aimed to evaluate the effects of aflatoxin-contaminated diet onhistopathological alterations of the gill, liver, kidney and intestine tissues in common carp. Fish wererandomly distributed into 15 tanks, i.e. in five experimental groups; (I) control fed with normal dietwithout solvent and aflatoxin, (II) positive control received feed with only solvent, and (III-V) fedon diets containing 0.5, 0.7 and 1.4 mg kg-1 of aflatoxin, respectively. After 21-days, 12 fish pertreatment were randomly caught, anesthetized and euthanized. Then, histological sections of thetissues were prepared. The main aflatoxicosis symptoms in the gills were fusion and disorganisationof the secondary gill lamellae, shortening of the secondary lamellae, inflammation of mucousmembranes, and exfoliation of the gill epithelium. Liver of the infected fish indicated cloudy swellingof hepatocytes, cellular hypertrophy, formation of vacuoles in the cytoplasm, and necrosis of liverparenchyma. Expansion of Bowman’s space, necrosis of urinary tract, exfoliation and degenerationof the urinary tract epithelium, expansion of the urinary lumen and dilation of the urinary space wereobserved symptoms in the kidney. Changes in the intestine of the aflatoxin-treated fish were; expansion of goblet cells, necrosis of mucous layers, exfoliation of the mucous epithelium, andbleeding in the intestinal wall. The results indicates that feeding common carp with dietscontaminated with aflatoxin, even in low concentrations (≤ 1.4 mg kg-1 feed) can causehistopathological damages and disturb their physiological balance.

Methyl paraben (MP) is widely used as a preservative in various products. It frequentlyenters into aquatic environment and renders potential threat to fish. The aim of this study was toevaluate reproductive toxicity of MP on zebrafish (Danio rerio) under laboratory conditions. Malezebrafish were exposed to four concentrations of MP (0.001, 0.01, 1, and 10 mg L-1) for 21 days insemi-static condition. Changes in mean length, mean weight, gonadosomatic index (GSI) andhistology of testis were studied. Treatment at 0.001 to 10 mg L-1 MP had no significant effect on thesurvival, mean length and mean weight of fish. But, GSI decreased in a dose dependent manner andthe decrease was significant in the group that received the highest dose. Histological alteration oftestis consisted of general testicular atrophy, multi-nucleated gonocytes (MNGs), impaired germ cell, spermatogonial proliferation, Leydig cell hyperplasia, interstitial fibrosis and apoptosis of Sertolicells. It was concluded that sub-chronic exposures of MP could adversely affect GSI, disrupt thehistology of testis and produce estrogenic and antispermatogenic activity in male zebrafish.

Understanding ecological and anthropogenic drivers of fish population dynamics andachieving a sustainable yield requires detailed studies on habitat selection and spatial distribution.The objective of this study was to predict spatial density and distribution of kilka species in thesouthern Caspian sea in relation to satellite-derived sea surface temperature, chlorophyll-aconcentration, turbidity and water depths using ordinary kriging and co-kriging geostatisticalmethods and introduction an appropriate potential fishing area according to the present fishing points.Three hundred and fifty fishing surveys were done in two main kilka fishing ports in the southernCaspian Sea (Anzali and Babolsar ports) from 2015 to 2016. The Geostatistical analysis showed thatthe co-kriging spatial interpolation method provided the best prediction of fish abundance whenchlorophyll-a content was included in model.