Factors associated with the prevalence of Perkinsus marinus in Crassostrea virginica from the southern Gulf of Mexico

Abstract

The protozoan Perkinsus marinus is considered the most important pathogen of the eastern oyster Crassostrea virginica, causing high mortality in natural and farmed oysters on the Atlantic coast of the US. In Mexico, no serious P. marinus epizootic has been reported. This study describes the current state of P. marinus prevalence in Terminos Lagoon (Mexico) associated with environmental factors including salinity, temperature, ammonium, nitrate, nitrite, silica, and phosphorus. In addition, the association of physiological (hemocyte density, protein concentration) and immunological (lysozyme, agglutination) parameters with the infection were studied. The prevalence was significantly different among seasons with mean values of 70, 23, and 7% in the dry (February to May), rainy (June to September) and north-wind (October to January) seasons, respectively. Only light infection intensity (Mackin scale value <1) was observed. Prevalence of P. marinus was associated with seasonal salinity, phosphorus, and silica variations. Comparisons of oyster health demonstrates that the rainy and north-wind seasons are stressful periods. Redundancy analysis showed that only 34% of the variation in seasonal P. marinus prevalence was explained by protein concentration (21%), lysozyme (12%), and agglutination (1%). Overall, the data suggest that freshwater input associated with high nutrient concentrations during the rainy and north-wind seasons has a strong negative effect on P. marinus prevalence and also influences the oysters' physiology. It is probable that this seasonal stress was responsible for the absence of an epizootic event in Terminos Lagoon. KEY WORDS: Perkinsus marinus · Crassostrea virginica · Environmental control · Salinity · Silica · ProteinResale or republication not permitted without written consent of the publisher

The Potential for Oysters,Crassostrea virginica, to Develop Resistance to Dermo Disease in the Field: Evaluation using a Gene-Based Population Dynamics Model

“…In extensive areas of the Gulf of Mexico, temperatures rarely drop below 10°C in the winter and often rise above 30°C in the summer, whereas salinities frequently exceed 15& for much of the time. (e.g., Copeland & Hoese 1966, Hofmann et al 1994, Soniat et al 1998, Gullian-Klanian et al 2008. Rates of proliferation of Dermo in vivo must be near maximal in these regions (Soniat 1985, Fisher et al 1992, Powell et al 1996.…”

“…Two diseases are most significant, MSX and Dermo caused, respectively, by the protistans Haplosporidium nelsoni and Perkinsus marinus (e.g., Andrews 1979, Ford & Haskin 1982, Andrews 1988, Ford & Tripp 1996. Of the two, Dermo is by far the most geographically widespread and, thus, a dominant factor in the population dynamics of the oyster over much of its latitudinal range (e.g., Wilson et al 1990, Ray 1996, Cook et al 1998, Ford & Smolowitz 2007, Gullian-Klanian et al 2008, Pecher et al 2008, but see Ulrich et al 2007). Dermo is routinely epizootic throughout much of the Gulf of Mexico (e.g., Powell et al 1992, Kim & Powell 1998, Soniat et al 2009, the southeastern coast of the United States (e.g., Burrell et al 1984, White et al 1998, Kim & Powell 2006, and north of Cape Hatteras at least to Delaware Bay (Jordan 1995, Ragone Calvo et al 2001, with sporadic outbreaks farther north (Brousseau 1996, Brousseau et al 1998, Ford & Smolowitz 2007.…”

Polymorphism at the ITS and NTS Loci ofPerkinsus marinusIsolated from Cultivated OysterCrassostrea corteziensisin Nayarit, Mexico and Phylogentic Relationship toP. marinusalong the Atlantic Coast

“…In North America, two species have been reported. Perkinsus marinus, which occurs along the Atlantic Coast from Maine, USA (Reece et al., ; Pecher et al., ) to Tabasco, in the Gulf of Mexico (Burreson et al., ; Gullian‐Klanian et al., ) and on the west Coast of Mexico and offshore in Hawaii. P. marinus is a pathogen to oysters ( Crassostrea virginica, Crassostrea gigas, Crassostrea ariakiensis , Crassostrea rizhoporae and Crassostrea corteziensis ), as well as several clam species (OIE, ).…”

First report of Perkinsus sp. infecting mangrove oysters Crassostrea rhizophorae from the Brazilian coast

“…found in a Brazilian mollusk host would show potential taxonomic affinities with a parasite found in Chinese oysters, rather than with Perkinsus spp. from neighboring regions, including P. marinus infecting C. virginica in the Gulf of Mexico (Gullian-Klanian et al 2008) and P. olseni infecting Pitar rostrata off the coast of Uruguay (Cremonte et al 2005). Future challenges include a full description of the Perkinsus sp.…”