Slow shell building, a possible trait for resistance to the effects of acute ocean acidification

Abstract

Increasing anthropogenic carbon dioxide is altering marine carbonate chemistry through a process called ocean acidification. Many calcium carbonate forming organisms are sensitive to changes in marine carbonate chemistry, especially mollusk bivalve larvae at the initial shell building stage. Rapid calcification, limited energy reserves, and more exposed calcification surfaces, are traits at this stage that increase vulnerability to ocean acidification through our previously argued kinetic‐energetic hypothesis. These developmental traits are common to broadcast spawning bivalve species that are the focus of most ocean acidification studies to date. Some oyster species brood their young, which results in slower development of the embryos through the initial shell formation stage. We examined the responses of the brooding Olympia oyster, Ostrea lurida, during their initial shell building stage. We extracted fertilized eggs from, O. lurida, prior to shell development, then exposed developing embryos to a wide range of marine carbonate chemistry conditions. Surprisingly, O. lurida showed no acute negative response to any ocean acidification treatments. Compared to the broadcast spawning Pacific oyster, Crassostrea gigas, calcification rate and standardized endogenous energy lipid consumption rate were nearly 10 and 50 times slower, respectively. Our results suggest that slow shell building may lessen the energetic burden of acidification at this stage and provides additional support for our kinetic‐energetic hypothesis. Furthermore, these results may represent an example of exaptation; fitness conveyed by a coopted trait that evolved for another purpose, a concept largely lacking in the current perspective of adaptation and global climate change.

Effects of seasonal upwelling and runoff on water chemistry and growth and survival of native and commercial oysters

“…As Olympia oysters spawn during the late spring to early fall (Baker ), larval oysters were outplanted during the upwelling season to reflect realistic exposure to environmental conditions. Reduced larval growth and survival in the outer‐bay where larvae were exposed to undersaturated water with respect to aragonite is consistent with some laboratory findings (Hettinger et al , Hettinger et al , but see Waldbusser et al ). Research in controlled settings also suggests that this exposure to corrosive water during early life stages has negative carry‐over effects at later juvenile stages, which could influence later ecosystem functioning (Hettinger et al ).…”

“…Pacific oysters originate from the Asian Pacific coast but are found in temperate waters globally, either in commercial aquaculture or as invaders in natural systems (Herbert et al ). Although there has been considerable work on the impacts of carbonate chemistry on commercial Pacific oysters (e.g., Barton et al ), and limited work with Olympia oysters (Hettinger et al , ; Waldbusser et al ), most of this research has taken place in laboratory and mesocosm settings where individual drivers are easily controlled and their impacts carefully measured. In natural settings, however, changes in carbonate chemistry do not happen in isolation, and oysters have been shown to be vulnerable to changes in temperature, salinity, DO, and food availability (Kimbro et al ; Wasson ; Hettinger et al ; Cheng et al ).…”

Carryover effects of temperature and pCO2 across multiple Olympia oyster populations

“…Indeed, the two groups to measure the response of O. lurida larvae to ocean acidification found contrasting results, no effect (Waldbusser et al. ) and slower growth (Hettinger et al. , ), possibly a result of local adaptation.…”

Competitive interactions moderate the effects of elevated temperature and atmospheric CO2 on the health and functioning of oysters

“…The 2 species, however, have different reproductive mechanisms (C. gigas, broadcast spawning; O. edulis, brooding), and it is possible that larval development could be differentially affected by climate change. Indeed, a similar species of brooding oyster, O. lurida, builds shells more slowly than C. gigas, potentially reducing the energetic burden of acidification at early life stages (Waldbusser et al 2016). It is possible that brooding species may have inadvertently evolved (exaptation) to cope with high CO 2 environments due to the CO 2 -enriched environment of the brood chamber (Waldbusser et al 2016).…”

“…Indeed, a similar species of brooding oyster, O. lurida, builds shells more slowly than C. gigas, potentially reducing the energetic burden of acidification at early life stages (Waldbusser et al 2016). It is possible that brooding species may have inadvertently evolved (exaptation) to cope with high CO 2 environments due to the CO 2 -enriched environment of the brood chamber (Waldbusser et al 2016). Whilst the present study has not considered the reproductive potential of either species in isolation or in competition, it is already known that multiple climatic stressors are particularly important for re production and during early devel opmental stages (Byrne 2011).…”