Tracing the impact and recovery trajectory of oil spill affected tropical rocky intertidal macrobenthic communities using the BOPA index

Abstract

A yearlong study was conducted to assess the impact of an oil spill on macrobenthos of rocky intertidal zone of Uran, India and its recovery processes, by comparing impacted site with a reference.Immediate acute effects observed were elevated sediment hydrocarbons, absence of macroalgae and amphipods, mass mortality of macrofauna and dominance of the opportunistic nereid, Namalycastis senegalensis.As the hydrocarbons reduced at the impacted site by ~50 % within three months, gradual re-appearance of macroalgae and re-colonization of amphipods (51.4 %) and sensitive polychaetes (7 %) indicated that the recovery was well underway.The amphipod, Allomelita pellucida proved to be a potential indicator of oil contamination.BOPA correlated with sediment hydrocarbons and performed effectively as the extant macrobenthic communities had sufficient representation of Polychaeta and Amphipoda.Notwithstanding the distinct initial impacts of the oil spill, comparable macrobenthic assemblages comprised of sensitive species at both sites after a year confirmed complete recovery