Parasites and pathologic conditions of the cockle Cerastoderma edule populations of the coast of Galicia (NW Spain)

A survey of pathological conditions affecting cockle populations of the mos t economically important natural beds of Galician estuaries in NW Spain was performed. Samples of 30 adult cockles were collected from each of 34 natu ral beds in the spring of 1999 and processed by histological techniques. Di sseminated neoplasia were seen in samples from most of the natural beds, in some cases with a high prevalence. The gregarine Nematopsis sp., larval tr ematode stages, and branchial extracellular large cysts enclosing bacteria- like microorganisms were the most prevalent parasites. Paravortex cardii, i ntracellular colonies of rickettsiae-like organisms in digestive and gill e pithelium Pseudoklossia sp. coccidians, Trichodina sp., an other ciliates w ere frequently seen in the samples. Copepods in gills and intestine and uni dentified gregarines in intestine epithelia and surrounding connective tiss ue were less prevalent and were observed in samples of some natural beds. L arge foci of heavy hemocytic infiltration were detected in a few sites only . Cysts of Steinhausia sp. and plasmodia and spores of a haplosporidian wer e seen in cockles from two localities. Inflammation was frequently observed in the samples. Some of the parasites and pathological conditions could be associated with mortality. (C) 2001 Academic Press.