The impact of a minor oil spillage in the estuarine Niger delta

On 24 April 1984 a barge sank in the Bonny Estuary, spilling 250 barrels of Nigerian crude oil. The incident occurred in an area where a baseline survey was already in progress. These data, plus additional studies at the spill-site enabled the impact of the incident to be determined. At the spill-site there was a near to total elimination of the littoral infauna and a highly significant oyster mortality, plus a 30% oiling of mangrove prop roots and 32% oiling of seedlings, which resulted in partial defoliation and death of seedlings within a 500 m² area. There were no significant effects on Uca tangeri density at the spill-site, and no effects at the nearest baseline survey transect 5 km away. The spillage was considered to be minor in terms of the quantity spilled, the effects observed, and their ecological significance.