Performance of oysters selected for dermo resistance compared to wild oysters in northern Gulf of Mexico estuaries

Abstract

The performance of the progeny of eastern oysters Crassostrea virginica from Louisiana selected for resistance to dermo, caused by Perkinsus marinus (referred to as 'OBOY') and of wild oysters collected from Louisiana (Calcasieu Lake) and Alabama (Cedar Point, Perdido Pass), USA, estuaries was compared for their potential use in aquaculture. Seed oysters from each stock were deployed in September 2011 at 2 dermo-endemic sites, Dauphin Island and Sandy Bay, Alabama, using an adjustable longline system, and their survival and shell heights were monitored bimonthly. P. marinus infection intensity and condition index were measured at deployment and in March, July and September 2012. The OBOY stock showed lower mortality than the unselected stocks (Cedar Point, Perdido Pass, Calcasieu Lake) at Dauphin Island, and both Louisiana stocks had lower mortality than the Alabama stocks at Sandy Bay, a slightly more saline site. Mortality increased in summer, especially between July and September, concomitant with increasing P. marinus infection intensities at the higher temperatures and favorable salinities. At the higher salinity site, both Louisiana stocks had lower P. marinus infection intensities than the Perdido Pass stock, the stock with the highest percentage of oysters with moderate and heavy infection and cumulative mortality. The OBOY stock reached greater mean shell height than Calcasieu Lake and Perdido Pass stocks. Condition index of the oyster stocks decreased by more than half between March and July following expected spawning. Differences in stock performance highlight the importance of stock selection for aquaculture in dermo-endemic estuaries of the northern Gulf of Mexico.

Effects of controlled air exposure on the survival, growth, condition, pathogen loads and refrigerated shelf life of eastern oysters

“…Growth rates decreased as the oyster size increased and generally followed previously described seasonal pattern for our region with the highest rates in fall when salinity was highest (Casas et al., ; Leonhardt et al., ). Oyster growth rate is well‐known to be dependent on initial size and increase with increasing salinity, as well as with increasing temperature (reviewed by Kraeuter, Ford & Cummings, ).…”

“…Subtidal oysters reached market‐size (75 mm) within 6 months after deployment or 10 months of age while oysters exposed to air weekly or daily reached market‐size within 9 months after deployment or 13 months of age. The rapid growth has been reported in other Gulf of Mexico estuaries such as Apalachicola Bay or Mobile Bay which is due to a continuous growing season in our nutrient rich subtropical estuaries (Casas et al., ). Temperatures are above 20°C for more than half of each year and rarely drop below 10°C, in contrast to more temperate or northern regions, where a period of no growth occurs in winter (Ingle & Dawson, ; Paynter & Dimichele, ).…”

“…A condition index based on the relation between dry meat weight and shell cavity volume that assesses the proportion of available internal cavity capacity occupied by the soft tissues would have been more suitable to use, since it specifically evaluates meat condition independently of shell weight (Abbe & Albright, ; Crosby & Gale, ; Lawrence & Scott, ). We have adopted a condition index based on shell cavity volume in our more recent studies (Casas et al., ; Leonhardt et al., ). Using condition index based on shell cavity volume, Littlewood et al.…”

Characterizing the Epigenetic and Transcriptomic Responses to Perkinsus marinus Infection in the Eastern Oyster Crassostrea virginica

“…Although previous studies have shown that C. virginica regulates gene expression in response to P. marinus, a major gap remains regarding whether there is a population-specific transcriptomic response to dermo in the northern Gulf of Mexico. Previous research has shown that oyster populations vary in mortality rates in response to dermo, though the molecular basis for this is still unclear (Casas et al, 2017;Leonhardt et al, 2017;La Peyre et al, 2019). A recent study looking at the effect of P. marinus infection on the global gene expression pattern of resistant vs susceptible C. virginica families found strong acute responses to infection with over 3,000 differentially expressed transcripts with resistant oysters upregulating genes involved with peptidase inhibitor activity and regulation of proteolysis (Proestou and Sullivan, 2020).…”

IoT applied to Environmental Monitoring in Oysters' Farms

“…In seasonal variation studies, the temperatures and salinities in the tanks tend to increase during the warm months, and to decrease in the cold months, in part due to the raining [4]. The increase in temperature and salinity tends to generate more mortality of oysters, but, at the same, time it allows higher growth rates due to the high amount of food availability.…”