CO2-driven ocean acidification repressed the growth of adult sea urchin Strongylocentrotus intermedius by impairing intestine function

Strongylocentrotus intermedius cultured in the northern Yellow Sea in China was utilized to evaluate the effects of chronic CO2-driven ocean acidification (OA) on adult sea urchins. Based on the projection of the Intergovernmental Panel on Climate Change (IPCC), present natural seawater conditions (pH(NBS) = 8.10 +/- 0.03) and three laboratory-controlled OA conditions (OA(1), Delta pH(NBS) = - 0.3 units; OA(2) , Delta pH(NBS) = - 0.4 units; OA(3), Delta pH(NBS) = - 0.5 units) were employed. After 60-day incubation, our results showed that (1) OA significantly repressed the growth of adult S. intermedius; (2) food consumption tended to be decreased with pH decline; (3) intestinal morphology was changed, and activities of intestinal cellulase and lipase were decreased under acidified conditions; (4) expression levels of two immune-related genes (SiTNF14 and SiTGF-beta) were altered; (5) rate-limiting enzyme activities of the glycolytic pathway and tricarboxylic acid cycle (TAC) were changed in all OA treatments compared to those of controls.