Organic matter source and distribution in the estuarine Apapa-Badagry Creek, Nigeria: Implications for living (stained) benthic foraminiferal assemblage

The Apapa-Badagry Creek in southwestern Nigeria is a largely man-impact area being bordered to the north by sprawling residential estates and industries and to the south by recreational centers and villages. It also houses the Lagos Harbour and petroleum terminals. Sewage from these complexes is discharged into the creek, thus the pollutants impact the living faunas, such as benthic foraminifera. The implications of organic matter (OM) type and source on the diversity and abundance of living benthic foraminifera in the Apapa-Badagry Creek are investigated. Results show that the distribution of the living benthic foraminifera in this area is largely dependent on sediment type, OM source, and salinity and that only ten species of living benthic foraminifera thrive in muddy sediments with TOC < 2 wt%. Carbon and nitrogen isotopes (δ13C and δ15N) and C/N molar ratios reveal that the OM is of terrestrial origin (C3 plants) and that it is not the ideal food for benthic foraminifera in this estuary, in particular, for Ammonia species.