South African Wild Coast Estuaries: spatiotemporal variations in the biochemical composition and the condition of the brown mussel Perna perna (Linnaeus, 1758)

Estuaries are amongst the most productive systems in the world, and their ability to influence adjacent systems is well established. This study aimed to investigate the biochemical composition (protein, lipid, carbohydrates, ash and moisture), condition index and the meat yield in soft tissues of the brown mussel Perna perna adjacent to two types of estuaries. Mussels were collected over two seasons, from two sites adjacent to permanently open estuaries and another two sites adjacent to temporarily open/ closed systems. Results showed significant seasonal and site-specific differences in the physico-chemical parameters, the biochemical composition, and the mussels' condition. The lipid, carbohydrate, ash content, CI and MY content had noticeable seasonal and site-specific variations for P. perna. Mussels near permanently open estuaries exhibited the highest biochemical composition content compared to those adjacent to temporarily open/ closed systems, during the dry season. Overall, the study demonstrated the importance of spatial, temporal and estuarine type variation in the biochemical composition as well as the condition of the mussels. These differences demonstrate the allochthonous influence of the permanently opened estuaries on the biochemical composition of the mussels, during the closed period of mouths in temporarily open/ closed systems during the dry season.