Résumé:
The aim of this work is to study the parasitism of a bivalve mollusk Mytilus
galloprovincialis, the examination of 180 individuals of Mytilus galloprovincialis harvested at
the three sites of the Annaba gulf during the winter and spring of the year 2022 Allowed the
collection of 12903 parasitic individuals distributed on the different tissues (mantle, gonad,
digestive gland),The identification of these parasites revealed the presence belonging to two
different classes of parasite, a protozoan Marteilia refringens (Comps, 1970) and a trematode
Parvatrema duboisi (Dollfus,1923). The values of the parasitic indices observed in the three
study sites were the subject of a comparative analysis. The results showed a significant
difference between the parasite populations probably due to the biotic and abiotic variability,
the species Marteilia refringens registers the most important parasite load (P=40% , A=76.38
I= 96.83 ), compared to the Parvatrema duboisi (P= 15% , A=9.4 I= 20.65 ). The distribution
of parasitic indices in Mytilus galloprovincialis at the three sites shows that Chapuis records
the highest parasitic load (80% and 74.83 parasites per bivalve examined respectively),
compared to the other two sites. In addition, a tissue effect was observed with a higher
infestation rate in the digestive gland compared to other tissues. All the results obtained are
related to the level of exposure of the sites to the various sources of pollution of urban,
agricultural, industrial and port origin. In addition, Mytilus galloprovincialis appears as a
model of choice that can be used as a bioindicator species of pollution in the Gulf of Annaba
