Monitoring of the prestige oil spill biological effects based on the biomarker approachmussel watch from Galicia to basque coast

Resumen

The aim of the present study was to assess the biological effects of the Prestige Oil Spill (POS) on the coastal ecosystems in Galicia and Biscay Bay by measuring selected cell and tissue-level biomarkers and histopathological alterations in sentinel mussels. The first crucial issue was the taxonomical identification of the Mytilus species that inhabits the North coast of the Iberian Peninsula. The results confirmed that all the wild mussels from Portugal to the Basque coast belonged to the species M. galloprovincialis. Seasonal variability was the second crucial issue. Seasonal variability was investigated in two representative localities, Oia (Galicia) and Mundaka (Basque Country), from April 2005 to May 2006. Only minor differences in biomarkers were recorded which enables the use of the same baseline values for both localities. In the Mussel watch programme carried out to assess the long-term effects caused by POS, mussels were collected in 22 localities from Portugal to the Basque coast over 3 years (2003-2006). Overall, the most remarkable POS effects were a drastic lysosomal membrane destabilization, lysosomal enlargement, changes in cell type composition, atrophy of the digestive alveoli and increases in cumulative intensity of parasitic infestations in 2003-2004, and in cumulative prevalence of inflammatory responses in 2005-2006. Although, VvL, VvBAS and Nematopsis sp intensity returned to reference values by 2004-2005, LP values, immune condition, granulocytoma intensity and MLR/MET were not fully recovered even in April-06. Single biomarkers provided useful mechanistic information to understand the biological responses to POS pollution. In addition, correlation and multivariate analyses were performed to facilitate the interpretation of the biomarker data recorded. Finally, five ecosystem health indices were applied: BAI, HSI, IBR, EHCC and IBI. All these integrative indices provided similar comprehensive evaluation of the ecosystem health status after POS at each locality and sampling time.