Abstract

The Lagos Lagoon in Nigeria faces significant human-induced stress, impacting its biodiversity and ecosystem dynamics, notably the benthic macroinvertebrates. A study was carried out to assess the impact of human activities on the abundance and diversity of benthic macroinvertebrates in the Lagos Lagoon. Twelve stations with varying human impacts along the Lagos lagoon were investigated monthly between November 2021 and April 2022. Water and benthic macroinvertebrates were collected monthly using Hydrobios Water Sampler and Van-Veen grab respectively, and analysed in the laboratory using standard methods. Statistical analysis revealed significant differences (P<0.05) in pH and Total Suspended Solids (TSS) among study stations, while other parameters showed no significant variation (P>0.05). Water temperature ranged from 27.3 to 29.7°C, with spatial variability observed. pH levels ranged from 6.2 to 7.0, indicating acidic to neutral conditions, potentially influenced by industrial activities. Salinity ranged from 5.0 to 17.0 ppt, highest in March, attributed to the dry season. Conductivity, Total Dissolved Solids (TDS), and Turbidity varied spatially, influenced by land use and runoff. Dissolved oxygen levels ranged from 4.5 to 6.9 mg/L, with lowest levels in April, potentially impacting aquatic biota. Principal Component Analysis (PCA) highlighted interrelations among physicochemical parameters, emphasizing salinity, conductivity, and TDS in specific stations. Benthic macroinvertebrate analysis revealed dominance by gastropods (64%), with low biodiversity and abundance, indicating disturbed ecosystems. Human activities are key drivers of water quality degradation and macroinvertebrate community changes, emphasizing the need for management strategies to preserve ecosystem health.