Persistent carry‐over effects of planktonic exposure to ocean acidification in the Olympia oyster

Abstract

Predicting impacts of global environmental change is challenging due to the complex life cycles that characterize many terrestrial and aquatic taxa. Different life stages often interact with the physical environment in distinct ways, and a growing body of work suggests that stresses experienced during one life stage can "carry over" to influence subsequent stages. Assessments of population responses to environmental perturbation must therefore consider how effects might propagate across life-history transitions. We investigated consequences of ocean acidification (decreased pH and carbonate saturation) for early life stages of the Olympia oyster (Ostrea lurida), a foundation species in estuaries along the Pacific coast of North America. We reared oysters at three levels of seawater pH, including a control (8.0) and two additional levels (7.9 and 7.8). Oysters were cultured through their planktonic larval period to metamorphosis and into early juvenile life. Larvae reared under pH 7.8 exhibited a 15% decrease in larval shell growth rate, and a 7% decrease in shell area at settlement, compared to larvae reared under control conditions. Impacts were even more pronounced a week after settlement, with juveniles that had been reared as larvae under reduced pH exhibiting a 41% decrease in shell growth rate. Importantly, the latter effect arose regardless of the pH level the oysters experienced as juveniles, indicating a strong carry-over effect from the larval phase. Adverse impacts of early exposure to low pH persisted for at least 1.5 months after juveniles were transferred to a common environment. Overall, our results suggest that a stringent focus on a single phase of the life cycle (e.g., one perceived as the "weakest link") may neglect critical impacts that can be transferred across life stages in taxa with complex life histories.

Preconditioning in the reef-building coralPocillopora damicornisand the potential for trans-generational acclimatization in coral larvae under future climate change conditions

“…Work in three brooding Pocilloporids, however, revealed that larval size was positively related to survivorship (Isomura and Nishihira 2001), suggesting that carry-over effects from a small larval size such as those seen in our study could result in cascading consequences in future life stages. This is true in the case of the Olympia oyster, where exposure to ocean acidification during development resulted in smaller shell sizes, and the latent effect of small size persisted for more than a month in ambient common garden conditions (Hettinger et al, 2012). It appears for corals, however, that small size is not always a certain predictor of negative performance, as large and small larvae exposed to temperature and salinity stress had the same propensity for latent effects in the coral Orbicella faveolata (Hartmann et al, 2013).…”

Ocean acidification increases the vulnerability of native oysters to predation by invasive snails

“…Oysters were raised through the larval phase and into early juvenile life at either an ambient partial pressure of carbon dioxide (pCO 2 ; targeted at 500 matm) or at an elevated level (targeted at 1000 matm; n ¼ 18 jars per level). The ambient level approximated a typical pCO 2 concentration that occurs presently during the summer months in Tomales Bay [18], whereas the elevated treatment was based on an increase of 500 matm, within the range of shifts predicted to occur by the end of this century [28]. The pCO 2 levels were established by filling the culture jars with FSW that had been held in 20 l carboys bubbled for 2-3 days with gas mixtures containing fixed CO 2 concentrations (traceable to the US National Institute of Standards and Technology).…”

“…The pCO 2 levels were established by filling the culture jars with FSW that had been held in 20 l carboys bubbled for 2-3 days with gas mixtures containing fixed CO 2 concentrations (traceable to the US National Institute of Standards and Technology). To minimize off-gassing and maintain the desired pCO 2 within the culture jars, the same mixed gases were added continuously to the sealed air spaces over the jars (for additional description of the culturing system see [18]). Every other day, 90% of the seawater in each jar was removed via reverse-filtration through 125 mm mesh, and jars were refilled with carboy water pre-equilibrated to the appropriate pCO 2 level.…”

Marine microplastics spell big problems for future generations

“…Reduced sperm swimming speeds, together with smaller, fewer eggs, will reduce fertilization success (16). Studies of other stressors, such as ocean acidification, show that carryover effects in oyster larvae can persist through to later life, reducing settlement success, population growth, and productivity (17).…”