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Author(s): Jonah U.E., Anyanwu E.D., Nkpondion N.N., Okoboshi A.C., Avoaja D.A..

Volume/Issue: Volume 3 , Issue 3 (2020)

Abstract:

A study on water quality and macro-benthic fauna of a brackish water system in Akwa Ibom State, Nigeria was carried out between May 2019 and February 2020. The samples were collected monthly, from three sampling stations across the water body. Standard methods were used to analyze water temperature, dissolved oxygen (DO), hydrogen ion (pH), electrical conductivity (EC) and turbidity in-situ and biochemical oxygen demand (BOD), phosphate and nitrate in the laboratory. Van-veen grab and standard hand net were used to collect the macro-benthos fauna. Ranges of physico-chemical parameters were Water temperature (24.9-25.3 ºC), EC (62.3-70.9 mS/m), pH (6.5-6.7), Turb. (12.0-28.2 NTU), DO (3.8-4.7 mg/L), BOD (2.3-3.2 mg/L), PO4- (3.2–5.2 mg/L), NO3- (3.0-6.3 mg/L). Statistical analysis showed significant differences in the mean values of turbidity, DO, PO4- and NO3-(P<0.05). Eighteen (18) taxa, 284 individual species of macro-benthic fauna, comprising three (3) phyla and seven (7) taxonomic groups were recorded. Arthropoda was the highest recorded phylum (73.94%); Annelida and Mollusca each accounted for 13.03% of taxonomic group recorded. The dominant taxonomic group was Diptera, accounting 23.9%. Shannon-Wiener index ranged between 1.997 and 2.530, Margalef’s index ranged from 1.865 - 3.309, Simpson index ranged between 0.846 and 0.905 and species evenness ranged from 0.908 – 0.923 indicating that the environment has gone through some level of perturbation. Most of the macrobenthic invertebrate species recorded were pollution tolerant species and physico-chemical parameters analyzed revealed that the estuary was polluted due to anthropogenic activities in the watershed.

Keywords:

Water Quality, Macrobenthic, Brackish Water, Anthropogenic Activities

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