Macrobenthic community structure and disturbance assessment in Gialova Lagoon, Ionian Sea

Gialova Lagoon, a coastal marine ecosystem in the Ionian Sea, suffered the impact of an oil spill incident in October 1993, leading to the extensive fish deaths when the oil tanker "Iliad" hit bottom in the entrance of the neighbouring Navarino Bay. A multidisciplinary study investigating the structure and functioning of Gialova Lagoon for the development of an integrated economic, social, and environmental management policy consistent with its conservation was carried out on a seasonal basis during 1995/1996. One of the research priorities was to investigate the structure and dynamics of the macrozoobenthic communities and assess whether these communities had recovered from the impact of the oil spill. The various methods applied (abundance/biomass comparison, distribution of species in geometric abundance and geometric size classes) revealed no detectable disturbance of the macrobenthic communities due to anthropogenic impact. However, it was proved that the lagoonal macrofauna suffered extreme natural disturbance due to a dystrophic crisis that occurred during autumn although they successfully recovered in subsequent seasons. Different sets of environmental factors were found to be highly correlated with the temporal and spatial distribution pattern of the macrobenthic communities and are discussed in detail. The coenocline observed in Gialova Lagoon appears to be strongly correlated with the degree of water exchange with adjacent marine and continental environments. © 2000 International Council for the Exploration of the Sea.