Biomarker responses to pollution in the Mediterranean green crab Carcinus eastuarii living in the Gulf of Gabès (Tunisia)

The central part of the Gulf of Gabès, in south-eastern Tunisia, is considered as one of the most sever pollution hotspots in the Mediterranean. However, because detailed studies are lacking little is known on the impact of pollution on the coastal organisms living in this area. We investigated this issue by using the Mediterranean green crab Carcinus aestuarii (Nardo, 1847) as a model species, and by considering a combination of morphological biomarkers (body condition and fluctuating asymmetry level) and biochemical ones (the activities of lactate dehydrogenase, alkaline phosphatase, as well as alanine and aspartate aminotransferase in the hemolymph and hepatopancreas). Our general approach was based on the comparison between crabs collected close to Gabès- Ghannouche factory complex of phosphate treatment, which is the source of coastal and marine pollution in this area, and crabs collected in one less contaminated site situated twenty-five kilometres faraway. We found that crabs living close to the factory complex were characterized by poorer body condition, higher level of fluctuating asymmetry and overall higher enzyme activities. These results show that the proximity to Gabès- Ghannouche factory complex was associated with remarkable perturbations in crab physiology, condition and development, revealing possible dangerous impacts of pollution on the whole coastal biodiversity in the Gulf of Gabès. Our results also stress once again, the usefulness of the Mediterranean green crab as a reliable species for biomonitoring in the polluted coastal habitats of the Mediterranean.