Effects of ocean acidification on the immune response of the blue mussel Mytilus edulis

Abstract

The effects of medium term (32 d) hypercapnia on the immune response of Mytilus edulis were investigated in mussels exposed to acidified (using CO 2 ) sea water (pH 7.7, 7.5 or 6.7; control: pH 7.8). Levels of phagocytosis increased significantly during the exposure period, suggesting an immune response induced by the experimental set-up. However, this induced stress response was suppressed when mussels were exposed to acidified sea water. Acidified sea water did not have any significant effects on other immuno-surveillance parameters measured (superoxide anion production, total and differential cell counts). These results suggest that ocean acidification may impact the physiological condition and functionality of the haemocytes and could have a significant effect on cellular signalling pathways, particularly those pathways that rely on specific concentrations of calcium, and so may be disrupted by calcium carbonate shell dissolution.

Effects of ocean acidification on immune responses of the Pacific oyster Crassostrea gigas

“…Nevertheless, OA exposure did not affect the apoptosis of hematopoietic tissue cell in the crustacean N. norvegicus [21]. Above all, OA had an impact on immune response of the Pacific oyster, which might be attributed to less energy spent on immune response [18].…”

“…For example, OA was found to impact survival, development, physiology and growth of many marine mollusks [32]. Furthermore, OA exposure can also disturb the energy metabolism and regulation which might affect immune function in bivalves [14,18]. Recently, it has been found that OA stress has the potential to promote pathogen development and survival, disease transmission and host susceptibility [33].…”

“…Recently, it has been found that OA stress has the potential to promote pathogen development and survival, disease transmission and host susceptibility [33]. However, only few studies have investigated the immune responses of mollusks under OA stress so far [18,19,34].…”

“…For example, inhibition of phagocytosis was observed in the mussel Mytilus edulis after exposure to elevated pCO 2 for 32 days [18]. The phagocytic capacity of hemocytes was inhibited by 60% after a 4-month exposure to elevated pCO 2 (hypercapnic seawater with a pH lowered by 0.4 units) in the crustacean Nephrops norvegicus [21].…”

Pathogenic challenge reveals immune trade-off in mussels exposed to reduced seawater pH and increased temperature

“…Despite this importance only a handful of studies have, to date, investigated the impact of OA on the immune system of a marine organism. The first study undertaken, carried out by Bibby et al (2008), exposed the blue mussel, Mytilus edulis, to reduced seawater pH for 32 days, measuring a number of key immune responses over the course of the experiment. Mussels maintained in reduced pH seawater (7.7, 7.5 or 6.7) displayed reduced phagocytic activity, compared with controls maintained at pH 7.8, after the 32 day exposure.…”