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Wetlands play an important ecological role by providing shelter and habitat for diverse fish species, migratory birds, macrophytes and other aquatic organisms. Hydrological connectivity with the main river channel has a critical role in fish diversity and production in floodplain wetland. The present study showed the seasonal hydrological alteration on fish species distribution in Ansupa wetland, connected with tropical river Mahanadi, India. The river discharge showed a variation from 4549 cusec during lean season (April) to 204716 cusec during monsoon (August). It has been recorded that water flows/discharge above 200000 cusec only, inundate the wetland resulting in exchange of free flows of fish species and nutrients. The study period for the fish species diversity was undertaken during 2017-18. A total of 46 fish species were observed under the orders Cypriniformes (18), Perciformes (12), Siluriformes (7), Synbranchiformes (2), Cyprinodontiformes (1), Clupeiformes (1), Beloniformes (1), Osteoglossiformes (1), Mugiliformes (1), Anguilliformes (1) and Tetraodontiformes (1). According to the conservation status of the International Union for Conservation of Nature, four species Parambassis lala, Ompok bimaculatus, and Anguilla bengalensis are in the category of Near Threatened. Analysis showed that taxonomic distinctness is more during winter than the monsoon and pre-monsoon, indicating monsoon could play a significant role in the fish species recruitment through river connectivity. Climatic data was analysed for a period of 34 years and indicated that an increment of 0.20C in water temperature and average increase of 129mm rainfall at the study site. This slight increase in rainfall over the years could be one of the factors responsible for the fish recruitment in the Ansupa wetland, through river connectivity underlining the importance of flood for wetland fisheries recruitment and sustainability. [ABSTRACT FROM AUTHOR]

Chilika Lake is the largest coastal lagoon in Asia and the second largest in the world covering an area of 1100 km2 and spread over three districts of Odisha state of India. It is the first Indian wetland designated as a wetland of international importance under the Ramsar Convention in 1981. The lake ecosystem sustains large and diversified resources of plants and animals including fisheries. Pollution of the ecosystem caused by residues of pesticides originating from different sources was assessed through multiple sampling from 2012 to 2016 from three potential sites of contamination, viz., Palur Bridge, Daya River Estuary, and Makara River. Incidence of organochlorinated (OC) pesticide residues was noticed in about 25% water samples. HCH (α, γ&δ), DDD (op|), DDE (op|&pp.|) and heptachlor were the OCs detected in concentration varying from 0.025 to 23.4 μg/l. None of the eight targeted synthetic pyrethroid (SP) pesticides was found in water, but among the organophosphates (OP), chlorpyrifos (0.019–2.73 μg/l), and dichlorvos (0.647 μg/l) were recorded. In sediment samples, residues of OC or OP pesticides were not present, but one SP pesticide was recorded. Fish samples were contaminated to the extent of 55%, mostly with residues of OCs and OPs and less with SPs. However, their concentrations were below the permissible limit, so there was no direct threat of health hazards to humans. [ABSTRACT FROM AUTHOR]

Analyzed were the length-weight relationship ( LWR) and length-length relationship ( LLR) of two fish species, Strongylura strongylura (family Belonidae) and Hyporhamphus limbatus (family Hemiramphidae) from Chilika Lake, India. A total of 616 specimens were sampled bi-monthly from August 2014 to June 2016 using seine nets and screen barrier nets operated by local fishermen that were used for the present estimates. [ABSTRACT FROM AUTHOR]

Mahanadi is one of the major rivers of peninsular India. Like other Indian rivers, it is contaminated with sewages, industrial discharges, and agricultural runoff. Thus, necessity was felt to monitor its pollution status. Present work was part of that program and aimed to assess the sediment contamination due to the trace metals Cd, Cr, Cu, Mn, Pb, and Zn during 2012-2015. Sediment pollution status and ecological risks were evaluated calculating contamination factor (CF), geo-accumulation (I geo ), pollution load index (PLI), potential ecological risk (E i R), etc. The recorded metal concentrations were Cd BDL of flame mode of AAS; Cr BDL - 73.9; Cu BDL - 44.4; Mn 37.2 - 1887.0; Pb BDL - 29.5; and Zn BDL - 92.5 mg kg -1 . As per US EPA guidelines, Cr concentrations at many locations were in the moderately polluted range. I geo , CF, mC d , PLI, and E i R indicated low pollution levels and low ecological risks due to the trace metals assessed. The sediment quality guidelines (SQGs) indicated that Cr and Cu concentrations exceeded (16% sample) the threshold effect concentrations and may occasionally exhibit adverse biological effects. The association of sediment organic matter, conductivity and content of Cu, and their grouping in component 1 of PCA revealed that the anthropogenic input was dominant and so also the component 2 where Cr exhibited moderately good correlation with organic matter. Cluster analysis of the sampling sites based on pollution status yielded 3 groups: relatively uncontaminated (S3, S4), low to moderately contaminated (S2), and moderately contaminated (S1, S5, S6) stretches.