Study the diversity and seasonal variations of endangered fishes, plankton and benthos in Kanchan river of Dinajpur

Abstract

This research work was carried out from February to June, 2018 to monitor the present status of endangered fishes, productivity and overall health status of Kanchan river situated in Dinajpur district. Water and sediment samples were collected twice in a month during the study period from the selected five different sampling sites along with required information about the availability of threatened fishes. The findings noted over 28 available threatened fish species in Kanchan river including several commonly available threatened fishes (Endangered: Acanthocobitisbotia, Somileptesgongota, Botiadario, Botialohachata, Bariliustileo, Barilusbengalensisetc.; Critically endangered: Channabarca, Labeonandina, Clupisomagaruaetc.) which are very rear in nationwide. Common planktonic flora and fauna of this riverine ecosystem were also identified. In the river several phytoplankton (Asterionella sp., Tabellaria sp., Clostridium sp. etc.) and zooplankton (Brachionus sp.) were monitored as season specific. Abundance of plankton were analyzed statistically significant (p <0.05) in different seasons. Plankton counting detected comparatively lower (23,000 per liter) and higher (39,000 per liter) numbers in the month of February and June, respectively. The observed benthic fauna of Kanchan river possessed 22 species of macro-benthos from different groups. Monitored minimum temperature (21.5 ºC) was recorded in the month of February and it was maximum in the month of June (30.5 ºC). These results suggested that productivity indicators (availability of planktonic flora and fauna including benthos) were better in the early monsoon season than the pre-monsoon season. Similarly, better ecosystem health (temperature, dissolve oxygen and availability of plankton) was also observed in early monsoon season. Seasonal variations of water temperature and dissolved oxygen were visualized significant (p <0.05). Finally, this study findings recommended to stop all manmade interventions for the better health of this riverine ecosystem as well as to take necessary actions for conserving the commonly available endangered and critically endangered fishes of Kanchan river.

Keywords

• diversity
• seasonal variation
• endangered fish
• plankton
• Kanchan River

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