Histopathologic Lesions in Bivalve Mollusks Found in Portugal: Etiology and Risk Factors

Abstract

Bivalve mollusks are an important resource due to their socioeconomic value and to the historical and genetic value of some species. Two nationally important oyster species-Portuguese oyster (Crassostrea angulata) and Japanese oyster (Crassostrea gigas) from distinctive areas in Portugal were studied to evaluate their sanitary status. Oysters were sampled from four different sites in Portugal. Oysters collected from Japanese oyster populations were cultivated in a strong ocean-influenced environment and Portuguese oyster populations were cultivated in wild-beds. The histopathological examination of both oyster species revealed the presence of parasites in gills, mantle epithelium, digestive gland tubules and connective tissue, with a moderate prevalence. In both populations was observed hemocytosis in the connective tissue, edema and metaplasia in the digestive gland and tissues necrosis. In wild populations from Sado and Mira estuaries the prevalence of mud blisters and gill lesions were higher than from populations produced on 0.50 m tables from mudflats. Biosecurity measures and diagnostic techniques are fundamental to control pathogenic agents, including the identification of pathogens at an early stage in their life cycles. This will prevent diseases and improve pathogen reduction on transport of animals from different countries and regions to new production areas to avoid the transmission of diseases.

Toxicological Evaluation of Acetylsalicylic Acid in Non-Target Organisms: Chronic Exposure on Mytilus galloprovincialis (Lamarck, 1819)

“…On the contrary, lamellar fusion and modifications of the epithelial normal structure were found at the longest exposure time (20 days). This suggests that the highest functionally more severe modifications occur in the gill tissues of molluscs in a later stage of the inflammatory response process, as reported by other authors ( Balamurugan and Subramanian, 2021 ; Pires et al, 2022 ).…”

Alien Species Associated with New Introductions and Translocations of Commercial Bivalves in Italian Marine Waters

“…Moreover, the spread of Vibrio tapetis along the European Atlantic coast is associated with Manila clam aquaculture practices [23,24]. Manila clam populations can also be affected by Cercozoa Haplosporidium tapetis [34] that can be widespread though the translocations of clams to other European countries.…”