Benthic Macrofauna of the Mgbuoshimini Axis of Elechi Creek, Bonny Estuary, Nigeria: Baseline for Ecological Monitoring

Benthic macrofaunal composition, abundance, were investigated in the Mgbuoshimini axis of Elechi Creek, Bonny Estuary, Rivers State, Nigeria, before construction of a proposed abattoir. Four stations were sampled bimonthly from April 2023 to February 2024. Sediment was collected with a 16 × 16 cm Van Veen grab and washed through a 0.5-mm sieve, the material retained was placed in labeled containers and fixed with 10 % formalin to which eosin was added. Three replicate benthic samples were collected at each station. Samples were sorted and all organisms were identified using appropriate keys and enumerated. Fifteen species belonging to five phyla and eleven families were recorded. Annelida had the highest number of species with 53% of species, followed by Arthropoda (20%), Mollusca (13%), Echinodermata (7%) and Chordata (7%). Polychaeta accounted for ca 98% of the relative abundance of benthos in the area. Seven polychaete taxocene were recorded from all stations and subjected to Analysis of variance (ANOVA) while Boccardia sp was found at only one station and not carried through. ANOVA did not give significant spatial differences Notomastus sp (p=0.416), Polydora sp (p=0.202) Nephtys hombergi (p=286) and Streblospio sp (p=0.437). However, there were significant differences between stations for Capitella capitata (p=0.001), Nereis diversicolor (p=0.009) and Lumbrineris sp (p=0.005). The results demonstrate spatial and temporal structuring of the benthic community and provide a baseline of polychaete taxocene for assessing ecological change that may be associated with the proposed abattoir during construction and operation.