Ecological implications of cultured mussel biodeposition for a short food web under winter conditions in the mediterranean sea

ln order to investigate trophic relationships in a simplified food chain including mussel biodeposition, in situ experiments were performed in an estuarine mussel-rope cultivation (Gulf of Fos). Cylindrical enclosures were placed at a depth of 2 m for one month during winter (sea temperature 10°C). Shrimps, Palaemon serratus, were kept in the cylinders, with and without mussel biodeposits as food supply. A control group was fed on mussel flesh. A comparison between the different biochemical components in both food and feeders was undertaken at three trophic levels; phytoplankton, mussels and shrimps. Under oligotrophic water conditions, shrimps could feed on mussel biodeposits. There were no noticeable differences between shrimps fed on mussel tissue or shrimps fed on mussel biodeposits, either in lipid and protein content, or in free amino acid, fatty acid or carotenoid pigment content. On the other hand, fasted shrimps exhibited significant modifications. The ecological significance of such anenergy flow pathway in intensive shellfish cultivation zones is discussed.