Community structure and distribution of phytomacrofauna in Iyagbe Lagoon, Southwest, Nigeria

Abstract

This paper reports the results of an investigation into the community structure and spatial distribution of phytomacrofauna inhabiting the roots of water hyacinth in Iyagbe Lagoon Southwest Nigeria. In all, 48 quantitative samples from eight sampling stations collected over a period of six months were analysed. Values obtained for environmental parameters ranged between 3.0 and 3.9 mg/L, 1.1 and 1.7 mg/L, and 40 and 119 cm for dissolved oxygen, biochemical oxygen demand and transparency respectively. Others were 0.52 - 50.0 mg/L for total dissolved solid, 0.02- 20.10 mg/L for total suspended solid, and 5.34-8.90 for pH. Three major phytomacrofauna groups; Annelida, Arthropoda and Mollusca were identified from a total of 1,976 individuals of phytomacrofauna collected from the study area. Arthropoda was the most abundant group with a total of 1,500 individuals and accounted for about 76% of the total phytomacrofauna population, Mollusca had 454 individuals accounting for 23.45% while, Annelida was represented by 22 individuals of polychaetes and constituted 1.11%. Total individuals observed at the sampling stations varied between 82 and 368. Number of species recorded in the sampling stations ranged from 13 - 24. There was significant difference in the number of individuals recorded for the sampling stations (ANOVA, F = 2.643, p < 0.05), a post-hoc test using Tukey’s HSD shows that number of individuals observed in stations 2, 7 and 8 were significantly lower than those of other sampling stations. The spatial variations in the results recorded suggest that the phytomacrofauna community was influenced by site specific factors particularly with respect to depth of study stations as shown by correlation analyses carried out.

Keywords: Water hyacinth, Phytomacrofauna, distribution, community structure, Iyagbe lagoon