Zooplankton community structure and dynamics during the transition from dry to rainy season: A case study of Kufena Inselberg (Rock) Pool, Zaria, Nigeria

Abstract

This study investigates the zooplankton community structure and dynamics of Kufena Rock Pool during the transition from dry season (March to April) to rainy season (May to June) in Zaria, Nigeria. Physicochemical parameters such as temperature, hydrogen ion concentration, electrical conductivity and total dissolved solids were determined in the field using Hanna instrument. Other parameters were determined in the laboratory using standard techniques. Zooplankton were collected using silk plankton net of 20 cm diameter and 65 μm mesh size with a plastic bottle of 60 ml capacity attached at the bottom. Canonical Correspondence Analysis was used to determine correlation between the physicochemical parameters and the zooplankton species abundance. The transition from dry to rainy season was marked by decreasing nutrient concentrations with nitrate nitrogen having the highest value 5.71mg/L in March and lowest value of 2.7mg/L in June and phosphate phosphorus decreasing from 2.5mg/L in April to 1.25mg/L in June. There was increase in ionic content of electrical conductivity (208μs/m in March to 284 μs/m in May), water hardness (57.16mg/Lin April to 101.54mg/L in June), alkalinity (56.33mg/L in March to 85.75mg/L in June) and total dissolved solids (108mg/L in March to 191.02mg/L in June). Zooplankton community structure showed that species diversity and abundance decreased during the transition from 24 in March to 16 in June. 30 species of zooplankton in 5 phyla were encountered with Rotifera having the highest species richness (9 species). Copepoda had the highest relative abundance of 25.4%. There was a significant association between physicochemical characteristics of water and the zooplankton species. This study revealed that the physicochemistry of the rock pool is not insulated from the environmental changes associated with the transition from the dry to the rainy season in Zaria, which leads to changes in zooplankton community structure.

Keywords: Zooplankton; dynamics; diversity; rock-pool; physicochemistry; Kufena