Parasitological survey of mangrove oyster, Crassostrea rhizophorae, in the Pacoti River Estuary, Ceará State, Brazil

Abstract

The mangrove oyster, Crassostrea rhizophorae (Bivalvia, Ostreidae) is commonly collected by fisherwomen in the estuaries of the Ceará State (CE), Northeastern Brazil. Despite the socioeconomic importance of this natural resource, there are few studies on the health of the oysters in this region. This study aimed to survey pathological changes in the mangrove oyster C. rhizophorae in the estuary of the Pacoti River, CE. Adult oysters were collected in August 2008 (N=450) and December 2009 (N=450) at three sites of the Pacoti estuary and in 2010 (N=600) samplings were done quarterly at one site which has showed the higher prevalence de Perkinsus. Macroscopical and histological analyses were used to evaluate pathological changes, Ray's Fluid Thioglycollate Medium (RFTM) to detect Perkinsus spp. and polymerase chain reactions (PCR) and DNA sequencing to identify Perkinsus species. In 2009, RFTM assay detected Perkinsus sp. infecting the tissues of C. rhizophorae with low prevalences of 1.3%, 6.7% e 7.3% in sites 1, 2 and 3, respectively, and in 2010, in site 3, prevalence was 2% (12 of 600 oysters). PCR did not confirm any positive case in 2009 and only 5 in 2010. The phylogenetic analyses strongly indicate that the Perkinsus species infecting oysters C. rhizophorae of this study belongs to Perkinsus beihaiensis. The histology confirmed 11 cases of Perkinsus sp. infecting the C. rhizophorae in 2009, and only two cases in 2010. Nematopsis sp. was the protozoan observed with greater prevalence (up 96.7%). Other found protozoa were: Trichodina, Sphenophrya, Ancistrocoma - like and an unknown ovarian parasite. The metazoa found were the polychaete Polydora with high prevalences, a turbellarian, possibly of the genus Urastoma, an unidentified digenean metacercariae and larvae of cestode Tylocephalum. A continuous monitoring of diseases in bivalves from this natural population is recommended, since the phylogenetic analyses indicate the occurrence of P. beihaiensis infecting oysters C. rhizophorae whose pathogenic potential is unknown.

Protozoan Parasite Perkinsus sp. Infecting Crassostrea rhizophorae From the Coast of Rio Grande do Norte (Northeast of Brazil)

“…The prevalence of infection by perkinsose were considerably lower than those found in studies with molluscs from other regions of Brazil, such as those found by Sabry et al [24,26] (5.78 and 23.33%) in the estuary of Pacoti with C. rhizophorae on the coast of Ceará. In C. rhizophorae on the coast of Bahia, the mean prevalence of Perkinsus sp.…”

“…Second da Sabry et al [26] the effects of perkinsosis on the host and the natural populations of oysters from the northeast region should be evaluated. It is imperative that they be introduced strategies to restrict the spread of the disease.…”

Growth, mortality and susceptibility of oyster Crassostrea spp. to Perkinsus spp. infection during on growing in northeast Brazil

“…This oyster species is also susceptible to P. beihaiensis, with very low prevalence (not exceeding 10%) and mostly light intensities (DANTAS-NETO et al, 2015;SABRY et al, 2009SABRY et al, , 2013.…”

“…Perkinsus spp. were recently reported in Brazil, infecting C. rhizophorae and C. gasar oysters and Anomalocardia brasiliana clams from the northeastern region (DA SILVA et al, 2013;FERREIRA et al, 2015;LUZ & BOEHS, 2016;QUEIROGA et al, 2013QUEIROGA et al, , 2015SABRY et al, 2009SABRY et al, , 2013. P. marinus and P. olseni are both notifiable to the World Organisation for Animal Health (OIE) and were reported to infect C. gasar oysters from the estuary of the São Francisco River, Sergipe State (DA SILVA et al, 2014).…”

Perkinsus sp. infecting the oyster Crassostrea rhizophorae from estuaries of the septentrional Northeast, Brazil

“…Histological sections of oyster tissues contained cells of Perkinsus sp. with a vacuole occupying most of the internal volume of the cytoplasm, an eccentric nucleus and prominent nucleoli, as described by Sabry et al (2009Sabry et al ( , 2013 and Brandão et al (2013). These authors detected changes in oyster tissues and organs infected by Perkinsus sp.…”