EFFECTS OF SOME ENVIRONMENTAL FACTORS ON TEMPORAL DISTRIBUTION OF ZOOPLANKTON IN LAPAI-GWARI STREAM, NIGER STATE, NIGERIA

Abstract

The impact of some environmental factors on the distribution of zooplankton in the Lapai-Gwari stream was investigated for a period of six months using standard techniques to understand the ecosystem dynamics, species interactions, and overall ecosystem health. Results revealed that all the physical and chemical parameters studied were significantly different monthly with a high total dissolved solids value observed in the month of April which was above the National Environmental Standards and regulation enforcement agency for surface waters. A total of 902 individuals of zooplankton were observed which was made up of 51% rotifers, 20% copepods, and 29% Cladocerans. The rotifers were also found to be more in the rainy months with Filinia terminalis dominating in the month of March. Among the copepods, Macrocyclops fuscus was found to dominate in May. Whereas among the cladocera, Alonella exigua, dominates in August. The eigenvalues from the canonical correspondence analysis accounted for 29.37% of all the environmental parameters that were observed from Axis 1 and the permutation test revealed no significant difference. Brachionus baylyi, Brachionus palas, Asplanchna multiceps, Brachionus sesssilis, Euchlanis mentameyers, and Asplanchna intermedia, appeared to be strongly associated with alkalinity and the months of June and July. From the physico-chemical parameters and zooplankton the stream appeared slightly perturbed with the presences of polluting indicator organisms like Asplanchna Species and the Brachionus, probably due to the various anthropogenic activities around the stream and resulting in low faunal diversity of zooplankton.