Relationship between specific dynamic action and food quality in the solitary ascidian<Emphasis Type="Italic"> Ciona intestinalis</Emphasis>

This study aims to determine the influence of the quality of food on specific dynamic action (SDA) in the ascidian Ciona intestinalis and thereby if respiratory measurements of SDA can be used to monitor the quality of a potential food source. Weight specific rates of filtration, ingestion and respiration of C. intestinalis were examined using two different experimental methods. Two food sources were selected, the flagellate Rhodomonas sp. representing a high-quality food source and the eelgrass Zostera marina representing a potentially low-quality food source. In spite of insignificant differences in weight specific rates of filtration and ingestion of Rhodomonas sp. and Z. marina, significant differences in weight specific respiration rates and weight specific ingestion rates of C. intestinalis at different particle concentrations of the two food sources were found. Ingestion of Rhodomonas sp. resulted in a SDA coefficient of 20%, whereas the respiratory increase after ingestion of Z. marina was insignificant. From the experimental results it is concluded that SDA of C. intestinalis is strongly dependent on the quality of the food ingested.Communicated by L. Hagerman, Helsingør