Influence of Labratrema minimus (Trematoda: Digenea) on filtration rate performance of edible cockle Cerastoderma edule the extreme temperature and salinity conditions (an in vitro experiment)

In order to demonstrate filtration rate of edible cockle Cerastoderma edule under different salinity and temperature conditions, two groups namely healthy and parasited with Labratrema minimus (Bucephallidae; Digenea) were compared. Results showed that the parasited ones had difficulties in adaptation to the extreme conditions of salinity and temperature. Our results also showed that a healthy cockle could filter ۷۸ ml min-۱g-۱ Flesh Dry Weight (FDW) seawater at ۲۰۰e temperature and ۳۴% salinity while an infested one processed ۱۵.۴ ml min-۱g-۱ FDW under the same conditions. In low salinity, which could happen during a rainy day and low tide, the healthy cockles processed ۱۴.۵ ml min-۱g-۱ FDW while infested cockles filtered ۱۸.۹ ml min-۱g-۱ FDW. Differences were not significant, however. Filtration rate of healthy cockles at a constant salinity but high temperature was ۱۰۱.۹ ml min-۱g-۱ FDW while the infested ones rated ۲۷.۲ ml min-۱g-۱ FDW. There was not a significant difference between their filtration rates at ۲۰oC and ۳۰oC. Our results showed that the parasited cockles were unable to adapt to extreme conditions when an increase in temperature or a decrease in salinity occurred. If these results could be extrapolated to natural situations, the ecological cause of mortality due to parasites could be proved and explained.

Keywords:

Filtration rate , Cerastoderma edule , Digenea , Host-parasite interactions , Himasthla , Labratrema