Effects of temperature and salinity on haemocyte activities of the Pacific oyster, Crassostrea gigas (Thunberg)

Abstract

The Pacific oyster, Crassostrea gigas, is extensively cultivated and represents an important economic activity. Oysters are reared in estuarine areas, subjected to various biotic and abiotic factors. One of the limiting factors in aquaculture is mortality outbreaks, which may limit oyster production, and the causes of these outbreaks are not completely understood. In this context, the effects of temperature and salinity on Pacific oyster, C. gigas, haemocytes, were studied. Haemocytes are the invertebrate blood cells and thus have been shown to be involved in defence mechanisms. Flow cytometry was used for monitoring several haemocyte parameters. An increase of temperature induced an increase of haemocyte mortality, in both in vitro and in vivo experiments. Temperature modulated aminopeptidase activity. An in vitro decrease of salinity was associated with cell mortality. During the course of in vivo experiments, an increase of phagocytic activity was reported at 15 per thousand and 50 per thousand. Environmental physical parameters may modulate haemocyte activities.

Withdrawn: “A health status survey of clams, Mya arenaria and Ensis siliqua, in the Irish Sea”

“…While varying environmental temperatures would seem to have affected the timing of gametogenesis in this population (Cross et al, 2012), neither energy used for spawning, nor the stress of oscillating environmental temperatures resulted in a disease state, as has been recorded in M. arenaria from other areas (Brousseau & Baglivo, 1991) and other bivalve species (Gagnaire et al, 2006;Harvell et al, 1999;Malham et al, 2009). …”

Descriptive epidemiology of mass mortality due to Ostreid herpesvirus-1 (OsHV-1) in commercially farmed Pacific oysters (Crassostrea gigas) in the Hawkesbury River estuary, Australia

“…There is no prior evidence to suggest that salinity plays any important role in OSHV-1 expression (EFSA, 2010). However, variation in salinity as well as extreme salinity values can significantly influence the immune systems of oysters and other bivalve molluscs, making them more susceptible to infection (Hauton et al, 2000;Gagnaire et al, 2006). The variation in salinity in the lower Hawkesbury River (26-38 ppt) was higher in February than in January but was within the acceptable range for this species.…”

Hemolymph microbiome of Pacific oysters in response to temperature, temperature stress and infection

“…In vitro experiments on oyster hemocytes revealed little change in immunocompetence over wide range of environmentally relevant temperatures (Ashton-Alcox and Ford, 1998;Gagnaire et al, 2006). Temperature stress, on the other hand, severely compromised host defenses (Malham et al, 2009), illustrating the need to examine temperature effects in broader context of animal condition and history.…”