Coral Larvae under Ocean Acidification: Survival, Metabolism, and Metamorphosis

Abstract

Ocean acidification may negatively impact the early life stages of some marine invertebrates including corals. Although reduced growth of juvenile corals in acidified seawater has been reported, coral larvae have been reported to demonstrate some level of tolerance to reduced pH. We hypothesize that the observed tolerance of coral larvae to low pH may be partly explained by reduced metabolic rates in acidified seawater because both calcifying and non-calcifying marine invertebrates could show metabolic depression under reduced pH in order to enhance their survival. In this study, after 3-d and 7-d exposure to three different pH levels (8.0, 7.6, and 7.3), we found that the oxygen consumption of Acropora digitifera larvae tended to be suppressed with reduced pH, although a statistically significant difference was not observed between pH conditions. Larval metamorphosis was also observed, confirming that successful recruitment is impaired when metamorphosis is disrupted, despite larval survival. Results also showed that the metamorphosis rate significantly decreased under acidified seawater conditions after both short (2 h) and long (7 d) term exposure. These results imply that acidified seawater impacts larval physiology, suggesting that suppressed metabolism and metamorphosis may alter the dispersal potential of larvae and subsequently reduce the resilience of coral communities in the near future as the ocean pH decreases.

Marine Invertebrate Larvae Associated with Symbiodinium: A Mutualism from the Start?

“…While the effects of ocean acidification have been investigated independently in marine invertebrate larvae and Symbiodinium (Brading et al, 2011;Nakamura et al, 2011;Waldbusser et al, 2013;Rivest and Hofmann, 2014), they yet need to be assessed on invertebrate larva-Symbiodinium associations. Nevertheless, it is known that the effects of ocean acidification on cultured (freeliving) Symbiodinium is phylotype-specific, with some strains (such as A13 and A2) in fact benefitting from it and increasing their photosynthetic capacity (Brading et al, 2011).…”

Adaptation and acclimatization to ocean acidification in marine ectotherms: anin situtransplant experiment with polychaetes at a shallow CO2vent system

“…When exposed to elevated pCO 2 , a number of taxa exhibit a marked downregulation of their metabolic rate or 'metabolic depression' [11,[13][14][15][16][17] but this is not ubiquitous. There are examples of upregulation [18][19][20], and no change in metabolism in response to elevated pCO 2 [11,[21][22][23][24].…”

Sources, factors, mechanisms and possible solutions to pollutants in marine ecosystems

“…delay the onset of calcification and alter crystal morphology and composition; increase juvenile mortality because of slower post-settlement growth; reduce effective population size and fecundity, and disrupt the generation of sturdy skeletons and the resilience of reef-building corals (Done, 1999;Langdon and Atkinson, 2005;Edmunds, 2007;Albright et al, 2008;Kuffner et al, 2008;Kurihara, 2008;Cohen et al, 2009;de Moel et al, 2009;Cohen and Holcomb, 2009;Buck and Folger, 2010;Morita et al, 2010;Albright, 2011;Albright and Langdon, 2011;Nakamura et al, 2011). Such effects have an impact on the overall growth and reproduction, and on populations of corals as a whole.…”