How healthy are cultivated scallops (Argopecten purpuratus) from Chile?: A histopathological survey

Abstract

Scallop (Argopecten purpuratus) cultivation is an important economic activity in the central-northern region of Chile, and diseases are a permanent concern for farmers and fishing authorities. A one year-long survey was undertaken to find out what parasites and putative pathogens are present in cultivated scallops from three locations: Caldera, Guanaqueros and Tongoy. Ninety adult scallops were sampled from each location, on each season of the year. The soft parts were fixed in Davidson´s fluid, and processed routinely for histology. The prevalence of infection for each parasite and pathologic condition were assessed. Larvae were sampled from three hatcheries and fixed for transmission electron microscopy. The same was done with digestive gland and gill tissues from the first 10 adults of each group sampled for histology. The same parasites and pathologic conditions were found in scallops from the three locations studied: inclusions of rickettsial-like organisms (RLOs) in epithelial digestive gland tubule cells of adults, and in the velar rim of one larva, haemocyte infiltration in gills and digestive gland, two types of granulomas of unknown aetiology in visceral and mantle connective tissues, mineral concretions in kidney, and the protozoan Trichodina sp., a ciliate ectoparasite, on the gills. However, the prevalences of all conditions varied greatly between the three sites and/or seasons. Based on the absence of significant mortalities among cultured scallops at the three sites during the reported survey year, it is concluded that the surveyed scallops were healthy, and that the pathological conditions reported here are generally benign.

Effects of the toxic dinoflagellate Alexandrium catenella on histopathogical and escape responses of the Northern scallop Argopecten purpuratus

“…Muscle alterations consisted of narrow holes in the muscle fibers filled by infiltrated hemocytes. Overall, after both 3 and 6 days, exposure of scallops to A. catenella triggered muscle alteration, melanization of the epithelium of several tissues (especially the foot), and increased prevalence of inclusions with rickettsiales-like organisms in digestive gland tubule cells (x 2 , P < 0.05), as described in Lohrmann (2009), even though, the intensity of infection was low (Table 1, Fig. 6A and B).…”

“…In the present study, most northern scallops, regardless of experimental treatment, showed a very high infiltration of hemocytes into the gonads and the digestive gland (84% prevalence). Lohrmann (2009) reported that hemocyte infiltration in the digestive gland was generally relatively low in the summer in northern scallops from Tongoy Bay, but could reach up to 70% in scallops from Caldera Bay. Our study was conducted at the beginning of the summer, which could explain the relatively high prevalence of hemocyte infiltration in all experimental scallops.…”

Report of pathogens and parasites in Perumytilus purpuratus from San Jorge Bay, Antofagasta, Chile

“…Along the Chilean coast, RLO have been previously reported in molluscs (Lohrmann et al 2002, Lohrmann 2009, Campalans & Lohrmann 2009 (Sun & Wu 2004) or they play a main role in causing mortality of molluscs (Braid et al 2005). In this study, the prevalence of RLO (22.2-40%) was moderate.…”

“…In South America, studies of parasites and diseases of bivalves are scarce (CaceresMartinez & Vasquez-Yeomans 2008), even though they are important and necessary. In Chile, major contribution about presence of parasites in molluscs have been recorded by Oliva (1984Oliva ( , 1992, Oliva et al (1986Oliva et al ( , 1999Oliva et al ( , 2010, Franjola & Gallardo (1991), Gallardo et al (1992), Oliva & Vega (1994), García-Tello et al (2002), Valderrama et al (2004), and pathogens by Lohrmann et al (2002), Lohrmann (2009), Campalans & Lohrmann (2009. However, the knowledge of pathogens and parasites in marine organisms inhabiting San Jorge Bay (Antofagasta) and the majority of the Chilean coast remains largely unknown.…”

Histopathological Assessment of Broodstock of the Razor ClamEnsis macha(Pharidae) from the Tongoy Bay, Chile

“…In all these cases, prevalence and intensity of infection were low, and there was no host reaction, and the same was observed in this study. In a former survey on scallops, Argopecten purpuratus, from the Tongoy Bay, the RLO harbored in digestive gland did not elicit any host response, and their prevalence fluctuated from 0% (January) to 36% (December), without a clear pattern (Lohrmann 2009). Juvenile scallops exposed to the toxic microalga, Alexandrium catenella, for 6 days increased the prevalence of RLO from 12% (control) to 37% (H egaret et al 2012).…”