For mussels living in estuarine systems where the seston quality and quantity is
constantly changing, it would make evolutionary sense to have evolved a feeding
strategy that maximizes energy assimilation but with minimal metabolic cost associated
with the processes of acquiring food from the environment. Our results suggest that this
indeed is the case, with the sorting of seston by the mussel to enrich the organic content
of the diet requiring little metabolic cost as compared to a non-selective feeding
behaviour. This conclusion is supported by a field study of Stenton-Dozey and Brown
Ž1994. who also found that under episodic tidal cycles such as during high tide, which
corresponds to high quantity and high quality of suspended particles, bivalves do sort
their diet and the cost of sorting is relatively low. Hence, it appears that mussels, in this
case the blue mussel M. trossulus is highly adapted to a dynamic food environment,
being capable of a flexible feeding strategy, which optimizes for the ingestion of organic
matter with minimal energetic costs to the animal.