engleski

Infection of Mytilus Galloprovincialis By the Trematode Parvatrema Sp. (Digenea: Gymnophallidae) in the Middle Adriatic Sea, Croatia

The species Mytilus galloprovincialis is a dominant bivalve in the rocky intertidal zone of the Adriatic Sea in Croatia. The population of M. galloprovincialis was declining in 2014, but the population recovered. In 2018, another population decline was recorded. As a result of these fluctuations, trematode infection was detected. Based on the morphology and anatomy of the sporocysts, cercariae, and metacercariae, the trematode species is identified as Parvatrema sp. A total of 60 individuals were collected from rocks in Kastela Bay in February and March 2014, 2018 and 2021. Based on histology, infection prevalence (number of infected mussels / total number of mussels) and weighted infestation (infection intensity / number of infected mussels) were calculated according to year of sampling, sex and length of mussels. Analysis of infection prevalence and infection intensity showed a decrease in infections between 2014 and 2021, while the calculated weighted infestation values indicate a high trematode infection potential, as results did not vary greatly between years. Both sexes and both length categories of mussels were susceptible to infection throughout the study period, with slightly higher values for males and a shorter length category of mussels. Based on the observations, there may be a resurgence of infection prevalence and a decline in the mytilid population in this area. Since the final host of gymnophallids is known to be marine and coastal birds, and assuming that in the Adriatic Sea the association between birds and trematode infection has not been reported so far, more attention should be paid to this issue.

Mytilus galloprovincialis ; Trematodes ; Histology ; Parvatrema sp ; Infection intensity

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