Feeding behaviour of the green mussel, Perna viridis (L.): Responses to variation in seston quantity and quality

Mussels, Perna viridis (Linnaeus), were exposed to different food suspensio ns consisting mixtures of sediment and microalgae (the diatom Skeletonema c ostatum and the green microalga Dunaliella tertiolecta). The designed range s for the contents were: total particulate matter (TPM: mg 1(-1)) 4.46-24.1 9, particulate organic matter (POM: mg 1(-1)) 0.75-7.19, particulate inorga nic matter (PLM: mg 1(-1)) 2.38-17.00, and organic content of seston (f) 0. 12-0.64. Clearance rates, rates of filtration, pseudofaeces production, ing estion and absorption, were analyzed at these various food quantity and qua lity. Clearance rates decreased exponentially with the increase of the part iculate organic matter. Pseudofaeces production was a positive function of the rate of particle filtration and more pseudofaeces was rejected when fil tered matter had a lower organic content. The ingestion rate decreased with the increase of the organic content of seston but the organic ingestion ra te increased slowly with the organic content of seston. The pre-ingestive f ood selection enhanced the rate of particulate organic matter ingestion and the organic enrichment of ingested matter became more pronounced for diets of low food value, of which most filtered matter was rejected as pseudofae ces. The absorption rate was dependent on the content of particulate organi c matter and the absorption efficiency increased as the organic content of ingested matter increased. Therefore, feeding processes of green mussels ap pear well adapted to cope with changes in food quantity and quality. At hig h particle concentrations but simultaneous low food values in the water col umn, green mussels have high rates of seston filtration and pseudofaeces pr oduction, together with preferential organic ingestion act to compensate fo r the dilution of organic matter in suspension. The results will be discuss ed with respect to spatial variations of the food environment and different ial growth of P. viridis in Hong Kong waters. (C) 1999 Elsevier Science B.V . All rights reserved.