Parasites and hystopathology of <i>Mullus barbatus</i> and <i>Citharus linguatula</i> (Pisces) from two sites in the NW Mediterranean with different degrees of pollution

Abstract

SUMMARY: The usefulness of fish parasite communities as bioindicators of environmental stress was tested on two benthic fish species, the red mullet (Mullus barbatus) and the spotted flounder (Citharus linguatula), during the spring of 2006 at two sites of the Catalan coast (northwestern Mediterranean): an anthropogenic-impacted area located close to the city of Barcelona, and a less polluted area close to Blanes (Girona). Gonadosomatic and hepatosomatic indices and condition factor were determined for the fishes caught. Prevalence, mean intensity, mean abundance and species richness of the parasites found in the survey were calculated for both species and locations, and the main histological alterations were recorded. Cysts of unknown aetiology and intestinal coccidians were reported only in red mullets from the area close to Barcelona, which were highly parasitized by the digenean Opecoeloides furcatus and the nematode Capillaria sp. However, a higher prevalence of Ichthyophonus sp. was reported in the spotted flounder from Blanes. Cysts of unknown aetiology, some nematodes and Ichthyophonus sp. may be associated with pollution.Keywords: bioindicators, Mediterranean, Mullus barbatus, Citharus linguatula, cysts of unknown etiology (CUEs), Ichthyophonus sp. RESUMEN: Parásitos e histopatología de Mullus barbatus y Citharus linguatula de dos zonas sometidas a diferente grado de contaminación del Mediterráneo noroccidental. -Se ha comparado la utilidad de las comunidades parasíticas de peces como bioindicadores de estrés ambiental en dos especies bentónicas de peces , el salmonete de fango Mullus barbatus y la solleta Citharus linguatula, durante la primavera de 2006 en dos lugares de la costa catalana (Mediterráneo NO): un área fuertemente impactada cerca de la ciudad de Barcelona, y una menos contaminada cerca de Blanes (Girona). Se determinó el índice gonadosomático, el índice hepatosomático y el factor de condición de los peces capturados. Se calculó la prevalencia, intensidad media, abundancia media y riqueza específica de los diferentes parásitos encontrados por especie y localidad, y se analizaron las principales alteraciones histológicas. Se han encontrado quistes de etiología desconocida y coccidios intestinales tan sólo en los ejemplares de M. barbatus de Barcelona, los cuales también estaban altamente parasitados por el digeneo Opecoeloides furcatus y el nematodo Capillaria sp. Se ha detectado Ichthyophonus sp. tan sólo en los ejemplares de C. linguatula, presentando una mayor prevalencia en los ejemplares de Blanes. Los quistes de etiología desconocida, algunos nematodos e Ichthyophonus sp. podrían estar relacionados con la contaminación.

Annual variation of parasite communities of deep-sea macrourid fishes from the western Mediterranean Sea and their relationship with fish diet and histopathological alterations

“…Their aetiology still remains unknown, and they have not been associated so far with any specific parasitic organism (MacKenzie, 1979;Munday and Brand, 1992;Nowak, 1996;Nowak et al, 2004;present work). Carreras-Aubets et al (2010) also reported the presence of these structures in Mullus barbatus and Citharus linguatula sampled in the continental shelf, in an area close to this study, and proposed a link between pollution and presence of these cysts, as Munday and Brand (1992) also suggested in other fish species. High organic carbon (Liquete et al, 2010), heavy metal (Sánchez-Cabeza et al,1999;Palanques et al, 2008) and organic pollutants values (PCBs, DDT, etc.)…”