SYMBIONTS AND DISEASES OF FARMED MUSSELS MYTILUS-GALLOPROVINCIALIS THROUGHOUT THE CULTURE PROCESS IN THE RIAS OF GALICIA (NW SPAIN)

Citation
A. Villalba et al., SYMBIONTS AND DISEASES OF FARMED MUSSELS MYTILUS-GALLOPROVINCIALIS THROUGHOUT THE CULTURE PROCESS IN THE RIAS OF GALICIA (NW SPAIN), Diseases of aquatic organisms, 31(2), 1997, pp. 127-139
Citations number
58
ISSN journal
01775103
Volume
31
Issue
2
Year of publication
1997
Pages
127 - 139
Database
ISI
SICI code
0177-5103(1997)31:2<127:SADOFM>2.0.ZU;2-3
Abstract
Mediterranean mussels Mytilus galloprovincialis were experimentally cu ltured from 5 rafts located in 4 Galician Rias, following the establis hed industrial procedure. Cultures were sampled monthly until mussels exceeded market size. Observation of histological sections of sampled mussels by light microscopy demonstrated symbionts which could be clas sified into 3 groups according to their pathogenicity. The first group consisted of symbionts with unnoticeable pathogenic effects including : prokaryotic inclusion bodies (PIE) in digestive gland and gills, an unidentified protistan in digestive primary ducts, a kidney coccidian, intracytoplasmic ciliates in digestive tubules, gill ciliates and a t urbellarian in the intestinal lumen. The second group comprised symbio nts that could damage the host, although unlikely to be lethal, includ ing: the microsporidian Steinhausia mytilovum, the flatworm Urastoma c yprinae, and the copepod Mytilicola intestinalis. The third group incl uded the protistan Marteilia refringens and the trematode Proctoeces m aculatus, potentially lethal pathogens. In addition, mussels with haem ocytic infiltration of tissues and granulocytomas and a few cases of d isseminated neoplasia were detected. The qualitative composition of mu ssel symbiont community was similar at the 5 study sites, except for 3 symbionts which were not detected at some sites. Quantitatively, symb iont loads were higher and histological signs of stress more abundant in Moana and Vilagarcia (the most inner sites in the Rias), intermedia te in Illa de Arousa and Muros, and lower in Lorbe. Symbionts increase d in prevalence as mussels grew. Some of the symbionts were detected i n mussel seed at the beginning of the experimental cultures.