Epizootiology of Perkinsus sp. inCrassostrea gasar oysters in polyculture with shrimps in northeastern Brazil

Abstract

Bivalve culture is of considerable economic and social interest in northeastern (NE) Brazil. The polyculture is an alternative approach to traditional monoculture for reducing the environmental impact of shrimp farming and improving oyster culture. Perkinsus marinus and Perkinsus olseni were found infecting oysters in NE Brazil and can threaten oyster production. This study evaluated Perkinsus spp. occurrence in Crassostrea gasar during all production stages. Oyster spats were produced in a hatchery and grown in shrimp ponds in Rio Grande do Norte state. Perkinsus spp. were surveyed by Ray's fluid thioglycollate medium and confirmed by polymerase chain reaction. Prevalence and intensity of infection were determined in oysters until they reached 7 cm. Results showed that the broodstock was already infected by Perkinsus (60%), but the derived spats were Perkinsus-free. Oyster spats acquired Perkinsus infection when transferred to ponds. The prevalence gradually increased in the seven months following placement in ponds (73%), and then decreased to 17% by the tenth month. The infections were initially mild, but intensity increased at the final growth stage. In conclusion, it is possible to produce Perkinsus-free C. gasar oyster spats from infected broodstock, and their culture in shrimp ponds is feasible.Keywords: Crassostrea gasar, hatchery, oyster, polyculture, Perkinsus sp., sanitary control. ResumoO cultivo de bivalves é de grande interesse econômico e social no Nordeste (NE) do Brasil. O policultivo é uma alternativa ao monocultivo tradicional de camarões para reduzir o impacto ambiental e melhorar a produção de ostras. Perkinsus marinus e Perkinsus olseni foram identificados infectando ostras no Nordeste do Brasil e representam uma ameaça a produção de ostras. Este estudo avaliou a ocorrência de Perkinsus spp. em Crassostrea gasar durante todas as fases de produção. Sementes de ostras foram produzidas em laboratório e cultivadas em viveiros de camarão no Rio Grande do Norte. Perkinsus spp. foram diagnosticados com o uso do meio de tioglicolato fluido de Ray e confirmado por reação em cadeia da polimerase. A prevalência e intensidade de infecção foram determinadas em ostras até atingirem 7 cm. Os resultados mostraram que os reprodutores encontravam-se infectados por Perkinsus (60%), mas as sementes produzidas estavam livres de Perkinsus. As sementes adquiriram a infecção por Perkinsus quando transferidas para os viveiros. A prevalência aumentou gradualmente nos sete meses após a colocação nos viveiros (73%) e, em seguida, diminuiu para 17% até o décimo mês. As infecções foram inicialmente leves, mas aumentaram até a fase final do crescimento. Em conclusão, é possível produzir sementes de ostras C. gasar livres de Perkinsus a partir de reprodutores infectados e seu cultivo em viveiros de camarão é viável.Palavras-chave: Crassostrea gasar, unidade de reprodução, ostras, policultivo, Perkinsus sp., controle sanitário.

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

“…Oysters from the present study showed a similar growth rate (5.8 mm and 6.6 g per month) compared to C. gasar oysters grown in shrimp ponds in the neighboring state of Rio Grande do Norte (5.2 mm per month) (DA SILVA et al, 2016). Moreover, the growth rate was better than oysters growing in shrimp ponds in the Sergipe state (2.37 mm per month) (ROSA, 2014) as well as in the marine and estuarine environments of South Brazil using spats produced in a hatchery facility (LOPES et al, 2013;PEREIRA et al, 2001).…”

“…Since 1990, spats are annually produced by the Laboratory of Marine Mollusks at the Federal University of Santa Catarina and are sold to local farmers. In contrast, recently (2014), a private enterprise implemented a hatchery facility in the northeast region to produce spats of C. gasar (DA SILVA et al, 2016). However, the supply of continuous spats is not certain because of the high costs of running these facilities and the need for financial support.…”

“…on the productive traits of oysters, such as growth and mortality, during the complete cultured period. For the first time, Da Silva et al (2016) evaluated the incidence of Perkinsus sp. in C. gasar oysters from spats reared in a hatchery facility to adult (commercial size) during growth in shrimp ponds.…”

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“…El estudio fue realizado en dos sitios localizados evaluated by means of the infection prevalence and intensity (Park et al, 1999;Encomio et al, 2005;da Silva et al, 2016). For instance, Cáceres-Martínez et al The level of incidence of this parasite in bivalve mollusks can vary from an innocuous occurrence, to a severe infection that damages the tissues.…”

“…The level of affection in bivalves caused by Perkinsus is dependent on several factors such as the species (native, non-native), latitude, environmental parameters, host immune system, parasite activity, and stressors as pollutants , and it is commonly Revista Bio Ciencias 6, e681. como contaminantes , y comúnmente, es evaluado por medio de la prevalencia e intensidad de la infección (Park et al, 1999;Encomio et al, 2005;da Silva et al, 2016). Por ejemplo, Cáceres-Martínez et al (2008) observaron una prevalencia baja e infección moderada de P. marinus en una población de C. corteziensis de la costa central del Pacífico Mexicano, y asociaron la presencia de este parásito en bancos naturales del ostión de placer, a la posible introducción de C. virginica infectado, traído de la costa este de los Estados Unidos de América al Golfo de México y diseminado después en el Pacífico Mexicano.…”