Diversity of metazoan parasites of the introduced oyster species Crassostrea gigas in the Exe Estuary

Temporal patterns in metazoan parasite community diversity of Crassostrea g igas, (Lamellibranchia: Ostreidae) were studied in the Exe Estuary at month ly intervals over one year and in relation to host age-classes. A total of four metazoan species was found to parasitize C. gigas in the Exe Estuary: the turbellarian Paravortex sp., cercaria Lepocreadiidae, metacercariae of Renicola roscovita and the copepod Mytilicola intestinalis. Only R. roscovi ta and M. intestinalis were present in all months throughout the year and i n all host age-classes. Analysis of the metazoan parasite community at indi vidual host level revealed little variation in community structure with res pect to season or host age, as only a slight increase in diversity values w as observed during the summer months. However, community diversity does var y from year to year, as shown by comparison between host age group samples in three consecutive years, None of the parasites are specialist to oysters but all appear to be widespread and abundant parasite of other lamellibran ch species.