Temporal dynamics in biomass and diversity of phytomacrofauna community in a two-arm lagoon, Southwest, Nigeria

Abstract

Background: Temporal variability in time and space is known to shape the distribution of organisms, their interactions and adaptations . In Nigeria, Southwest region in particular, studies investigating patterns in phytomacrofauna attributes are scarce. Objectives:  This study reports the temporal patterns in biomass, density and diversity of phytomacrofauna community in a two-arm lagoon, Southwest, Nigeria. Methods: Monthly samples collected for seven consecutive times at eight sampling locations were used for this investigation. Results: Of all the physico-chemical variables investigated only salinity was significantly different (ANOVA, F = 5.33, p < 0.05) among sampling months. There was a significant difference in the biomass (ANOVA, F = 2.983, p < 0.05) recorded for the sampling months. Monthly biomass varied between 552 and 2976 gm^-2, with November and January recording the lowest and highest values respectively. Of the three phytomacrofauna phyla (Mollusca, Arthropoda, Annelida) collected, mollusca recorded the highest (3548 gm^-2) biomass during the study period. Monthly density varied between 960 and 5810 ind/m² with May and February recording the lowest and highest values respectively. There was no significant difference in the monthly density (ANOVA, F = 0.485, p > 0.05) of phytomacrofauna. The phylum arthropoda recorded the highest (15000 ind/m²) density among the three phyla collected. Temporal variation in density of phytomacrofauna was similar to the pattern displayed by biomass. The month of May supported the highest phytomacrofauna diversity and species richness. Conclusion: Overall pattern displayed in the results suggests an overwhelming influence of   temporal changes in environmental conditions  on the phytomacrofauna variables.

Keywords: Phytomacrofauna, biomass, diversity, physico-chemistry, lagoon