Effect of Aureococcus anophagefferens (brown tide) on growth and feeding of the mussels Perna Viridis

The effects of brown tide algae species Aureocuccos anophagefferens and its mixture with Tetraselmis subcordiformis on the growth and feeding of the mussels Perna viridis were investigated in laboratory.The results showed that A.anophagefferens had a significant negative effects on the growth and feeding of mussels Perna viridis.The soft tissue fresh weight, dry weight and ash free dry weight (AFDW) of mussel fed on both high and medium cell densities of pure culturing A.anophagefferens were significantly lower than those of messel fed on mixed algae groups, the growth condition index (CI) of mussel decreased significantly as well, and the decrease rate was even lower than those mussels treated with starvation.The CI, fresh weight, dry weight and AFDW of mussels exposed to mixed algae group were significantly lower than control groups, and the decrease rate was related to the concentration of A.anophagefferens in mixed algae groups.When the concentration of A. anophagefferens in mixed algae group was higher (≥ 4×10⁵cells/mL), the above indexes of mussels were even obvious lower.The feeding rates of mussels exposed to the mixed algae groups were significantly lower than that in the control group.The inhibitory effect on mussel feeding was also related to the cell density of A.anophagefferens, and the ingestion rate of mussel exposed to the groups of mixed high concentration A.anophagefferens was lower than that in the control group.These results suggested that the inhibitions were not only because A.anophagefferens cell size was too small to be ingested normally by mussel, but also the algae species could produce some toxic substance that inhibited the feeding and growth of mussels.To some extent, the inhibitory effect could be alleviated by the behaviour of mussels fed on T.subcordiformis simultaneously.