Evaluating the histopathology, condition index and stress-on-stress response of caged brown mussels Perna perna for monitoring marine coastal pollution in Senegal

Abstract

This study is the first in a coastal West African country to evaluate the histopathology, condition index and stress-on-stress response time of caged brown mussels Perna perna for use in pollution monitoring of coastal ecosystems. Perna perna collected from an unpolluted area on the coast of Senegal were divided and transplanted to a polluted site or maintained at the reference site for an exposure–depuration experiment. After 4 weeks of exposure, the mussels deployed at the polluted site (Port of Dakar) were then transferred to the cleaner reference site (Pointe des Almadies) for depuration. Mussels exposed to the polluted waters of the seaport had bioaccumulated polycyclic aromatic hydrocarbons (PAHs) as well as lead, copper and selenium; furthermore, changes were observed in their digestive gland histology, and their stress-on-stress response measured as median survival time (LT₅₀) had decreased. By the end of the 4-week depuration period at the reference site the mussels showed signs of recovery, specifically in terms of their digestive tubule architecture and tolerance to air exposure. The results demonstrate that caged P. perna could be used as bioindicators for monitoring coastal environmental pollution in West Africa.