Zooplankton abundance and diversity of fishponds exposed to different management practices

Abstract

The taxonomic composition and community structure of zooplankton faunae of selected earthen fishponds in Ife North Local Government Area of Osun State, Nigeria were investigated for a period of two years sampling every other month. The study was based on three sets of fishponds with regards to fertilization practice and water flow regime. These include non flow-through ponds that received organic and inorganic fertilizers (FNF); flow-through ponds that received organic and inorganic fertilizers (FF) and unfertilized flowthrough ponds. The zooplankton fauna of the fishponds comprised of 81 species belonging to three phyla namely Rotifera (62 species belonging to 16 families and two orders), Arthropoda (6 cladocerans, 2 copepods, 6 ostracods, 4 insecta and one arachnid species) and Protozoa which was represented by only one species. Zooplankton species richness indices were generally higher in the flow-through ponds than in the non flow through ponds with some species occurring only in the fertilized flow-through ponds. The flow-through pond had the highest number of species 54, while the least number of species 37 was recorded from the non flowthrough pond. The fertilized non-flow-through ponds also had the .highest mean abundance of 36762 ± 56162 ind/m³, followed by fertilized flow-through ponds (34346 ± 40784 ind/m³) and non-fertilized flow-through ponds (16006 ± 41263 ind/m³) descending order. The means in zooplankton abundance among the ponds were, however, not statistically significant. The fertilized ponds supported zooplankton abundance while continuous water flow as observed in the flow-through had direct influence on diversity and species richness. Hence to achieve the desired effect of pond fertilization on its primary productivity, this must be accompanied by adequate water flowage especially in shallow fish ponds.

Keywords: Zooplankton, community structure, diversity, fish ponds, fertilization.