The Distribution and Seasonal Variation of Zooplankton Species of the Great Kwa River, Calabar, Nigeria: A Reassessment Approach

Background: Human activities adversely affect the distribution and diversity of zooplankton. They are diverse group of organisms with little or no locomotive ability and quickly respond to changes in their environment. This research was aimed at providing updated information on the distribution and seasonal variation of zooplankton in Great Kwa River.

Materials and Methods: Two sampling stations (S1- Obufa Esuk and S2- Esuk Atu) were mapped along the river bank, samples were collected using plankton net of 55µm mesh size and preserved in 4% formalin. Species were identified using taxonomic keys. Data were analyzed using ecological indices.

Results: The results revealed 12 taxa; belonging to 38 species. Tintinnida, Protozoa, Cladocera, Copepoda were 23.1%, 18.5%, 15.4% and 13.3% respectively. The lowest taxonomic groups were Diptera, Foraminitera, Atenatadata and Trichoptera having 1.85% for each order. The highest species was recorded in S2 having 31 species. In both Stations Ascampbelliella acuta was dominance over other species. Shannon-Weiner index (H) were 2.997 and 2.40 in S2 and S1 respectively. The evenness index were 0.576 and 0.547 for S1 and S2 respectively. Margalef,s diversity index were 8.171 and 4.111 for Esuk Atu-S2 and Obufa Esuk-S1 respectively. Zooplankton species were abundant in wet season than dry season.

Conclusion: This present study provide updated information on the zooplankton distribution, diversity and seasonal variations of the Great Kwa River. The high dominance of Tintinnida in this study indicates a natural linkage between nano-planktons and macro-planktons in the food webs of the river.