Abstract
The mangrove oyster Crassostrea rhizophorae is an estuarine resource exploited by riverside communities in Northeast Brazil. Despite its socioeconomic importance, studies on the health status of this bivalve are scanty in this region. The purpose of the present study was to investigate the presence of the protozoan Perkinsus sp. in C. rhizophorae collected in August and September 2011 in three estuaries of the septentrional Northeast, Brazil: Jaguaribe (Ceará), Camurupim (Piauí) and Carnaubeiras (Maranhão) (n= 150 specimens/site). The samples were submitted to Ray's fluid thioglycollate medium (RFTM), PCR and histology assays. The RFTM assay revealed spherical, blue or bluish-black hypnospores of the genus Perkinsus in 50 specimens (Jaguaribe= 17.3%, Camurupim= 5.3%, Carnaubeiras= 10.6%). The intensity of the infection ranged from very light (1-10 cells per slide) to severe (more than 40 cells in each of 10 fields of the slide) for Jaguaribe; very light for Camurupim and very light to moderate (at least 40 cells observed in each of 10 fields of the slide) for Carnaubeiras. When submitted to confirmatory PCR analysis, 6 cases were confirmed (Jaguaribe=3, Camurupim=1, Carnaubeiras=2). The histology confirmed 21 cases of infection in specimens from the three estuaries. Although local collectors have reported no mortality in oyster populations that might be attributed to infection by Perkinsus, health surveillance of oyster populations in the septentrional region of Northeast Brazil is advisable.
Highlights
The protozoan Perkinsus sp. belongs to a group of parasitic protozoa which infect mollusks worldwide, bivalves
According to the Office International des Epizooties (OIE), two species of the phylum Perkinsozoa, Perkinsus marinus and Perkinsus olseni, are notifiable (OIE, 2012) due to the substantial mortality rates and economic losses with which they are associated around the world (Villalba et al, 2004; Choi and Park, 2010)
Fifty oysters from the three collects tested positive for perkinsiosis in Rays fluid thioglycollate medium (RFTM) (50/450)
Summary
The protozoan Perkinsus sp. belongs to a group of parasitic protozoa which infect mollusks worldwide, bivalves. Since the first report of Perkinsus marinus infecting the American oyster Crassostrea virginica (Gmelin, 1791) in the Gulf of Mexico (Mackin et al, 1950), other species of the genus Perkinsus have been reported infecting several species of marine mollusks around the world (Lester and Davis, 1981; Azevedo, 1989; Blackbourn et al, 1998; Villalba et al, 2004; Choi and Park, 2010). P. marinus was responsible for substantial losses in populations of the American oyster C. virginica along the U.S Atlantic coast and the Gulf of Mexico (Burreson and Calvo, 1996), while P. olseni is known to have decimated populations of the abalone Haliotis rubra in Australia (Lester and Davis, 1981) and of the clam Ruditapes decussatus in Portugal (Azevedo, 1989). Molecular studies have recognized seven species of the genus Perkinsus: P. marinus, P. olseni (=P. atlanticus), P. mediterraneus, P. qugwadi, P. honshuensis, P. beihaiensis and P. chesapeaki (=P. andrewsi) (Burreson et al, 2005)
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