ABUNDANCE OF ZOOPLANKTON AND ITS RELATIONSHIP WITH SOME PHYSICO- CHEMICAL PARAMETERS OF RIVER RIMA IN KWALKWALWA PORTION OF SOKOTO STATE, NIGERIA

Résumé

This study was conducted in Kwalkwalwa area of River Rima Sokoto, Sokoto state, Nigeria. It aimed at assessing abundance of zooplankton and its relationships with some physico-chemical parameters. Three sampling stations were selected as station A (shoreline site), B (Fishing activities. area) and C (Farming and irrigation site).  Four seasons were observed. Eight physico-chemical parameters including, temperature, dissolved oxygen, turbidity, pH, electrical conductivity, phosphate and nitrate were measured monthly using portable instruments concurrently with collection of zooplankton samples at each sampling point at depths between 0.1m and 0.5m. All physico-chemical parameters were significantly (P<0.05) different between the four seasons. Nine species of zooplankton were discovered belonging to three groups namely; rotifers, cladoceran and copepods Off these, 2 species were contributed by Rotifera, 2 Cladocera and 5 Copepoda. However, the copepods had the largest contribution in terms of abundance in all the four seasons. The calculated season-wise diversity indices values, for each group of zooplankton showed no considerable degree of differences as all the species were recorded in all the four seasons. Generally, with the exception of turbidity and pH, there was no significant (P>0.05) correlation between zooplankton abundance and physico-chemical parameters. The results showed that there was positive and significant (P<0.05) relationship between turbidity and zooplankton during early wet season. Agroforestry practices should be promoted in the river`s catchment area in order to reduce sedimentation in the lake and on land deforestation.