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

Abstract

a b s t r a c tOcean acidification (OA), caused by anthropogenic CO 2 emissions, has been proposed as one of the greatest threats in marine ecosystems. A growing body of evidence shows that ocean acidification can impact development, survival, growth and physiology of marine calcifiers. In this study, the immune responses of the Pacific oyster Crassostrea gigas were investigated after elevated pCO 2 exposure for 28 days. The results demonstrated that OA caused an increase of apoptosis and reactive oxygen species (ROS) production in hemocytes. Moreover, elevated pCO 2 had an inhibitory effect on some antioxidant enzyme activities and decreased the GSH level in digestive gland. However, the mRNA expression pattern of several immune related genes varied depending on the exposure time and tissues. After exposure to pCO 2 at~2000 ppm for 28 days, the mRNA expressions of almost all tested genes were significantly suppressed in gills and stimulated in hemocytes. Above all, our study demonstrated that elevated pCO 2 have a significant impact on the immune systems of the Pacific oyster, which may constitute as a potential threat to increased susceptibility of bivalves to diseases.

Hemocyte responses of the thick shell mussel Mytilus coruscus exposed to nano-TiO 2 and seawater acidification

“…In M. coruscus hemocytes, the significantly increased HM was found as a result of a nano-TiO 2 exposure, indicating a high susceptibility to NP, which agrees with the result on the green-lipped mussel Perna viridis . Moreover, similar results were also obtained for the oyster C. gigas under acidification (Wang et al, 2016), suggesting that a significant increase of HM may be associated with insufficient antioxidant enzyme activities induced by stress. Additionally, significant interaction was found at 7 and 14 d, implying that pH and nano-TiO 2 brought a more severe effect to mussel in the long-term exposure.…”

“…The pH effect on ROS was also the same. In the oyster C. gigas, a significant increase of ROS was observed after one month of exposure to acidification (Wang et al, 2016). Based on our results, the significant interaction started from 14 d. Even in the recovery period, low pH could accentuate the negative effect induced by nano-TiO 2 .…”

“…Additionally, Canesi et al (2015) reported that phagocytosis of the mussel M. galloprovincialis exposed to high concentration of polystyrene nanoparticles decreased, and similar responses were also observed under acidification (Bibby et al, 2008). Wang et al (2016) found a reduction of phagocytosis induced by low pH. Although limited information is available on mechanisms for phagocytosis reduction caused by NP and acidification, lysosomal destabilization seems to be one of the possible causes.…”

The capacity of oysters to regulate energy metabolism‐related processes may be key to their resilience against ocean acidification

“…In the context of OA, Wang et al. () recently identified increases in the number of apoptotic cells and in the production of reactive oxygen species (ROS) in Pacific oysters ( C. gigas ) in response to elevated CO 2 (2,062 ppm p CO 2 , pH 7.55). At the transcriptional level, Crassostrea virginica showed changes in the relative expression of genes involved in biomineralisation, stress and immune functions under CO 2 stress (3,523 μatm p CO 2 , pH 7.5 and 2,000 μatm p CO 2 , pH 7.6) (Beniash, Ivanina, Lieb, Kurochkin & Sokolova, ; Ivanina, Hawkins & Sokolova, ).…”

Contrasting impacts of ocean acidification and warming on the molecular responses of CO2-resilient oysters

“…For instance, under elevated CO 2 conditions, oysters exhibit weaker shells [9], higher mortality rates and lower soft tissue growth [10], as well as impaired immune functions (e.g. increase in apoptosis and reactive oxygen species production) [11]. Such pervasive impacts may ultimately affect the survival and sustainability of entire populations, especially when coupled with a warmer ocean.…”