Ocean acidification has subtle and complicated effects on fish because it often affects only the earliest life stages and interacts with other stressors. This project pulled together several types of data from multistressor experiments on Atlantic silversides, an abundant fish along the East Coast, to model their energy budget throughout the life cycle. Using Dynamic Energy Budget theory (DEB) we are able to incorporate different effects at each life stage to reflect the increased tolerance adults have relative to embryos and larvae. Energy budgets can help us test hypotheses about how energy is allocated to needs like homeostasis and reproduction under acidification, and ultimately estimate population-level effects.

Using Gene Silencing to Validate the Role of Perlucin Gene in Oyster Resilience to Ocean Acidification

Caroline Schwaner, Stony Brook University 

We previously investigated the molecular mechanisms associated with resilience to ocean acidification in Crassostrea virginica. There were significant differences in SNP and gene expression profiles among oysters reared under normal and OA conditions. Both of these approaches showed similar results, particularly in genes related to biomineralization, including perlucin. In this study, we used RNAi or gene silencing to validate findings and confirm the protective role of perlucin associated with resilience to OA. Silenced oysters under acidification stress were the smallest, had shell abnormalities, and had significantly reduced shell mineralization, thereby indicating that perlucin does help larvae mitigate the effect of OA.

Impacts of extreme events on carbonate system variability in the York River Estuary: a numerical model study

Fei Da, Virginia Institute of Marine Science

Better understanding the carbonate system variability during extreme events will help predict future changes and provide critical information for the local shellfish aquaculture industry. In this study, a coupled hydrodynamic-biogeochemical 3-D high-resolution model is used to investigate the primary controls of the carbonate system in a small sub-estuary of the Chesapeake Bay: the York River Estuary. Net horizontal advection, air-sea CO2 flux, and net community production all play crucial roles in controlling dissolved inorganic carbon (DIC) and pH, while total alkalinity is relatively conservative. During extreme high discharge events, pH reductions are associated with net heterotrophy and net advection of high DIC upstream water, with increased outgassing playing a counteracting role.

Influence of water quality history on future ocean acidification tolerance in larval eastern oysters in Chesapeake Bay

Anthony Himes, Virginia Institute of Marine Science

One species of calcifying organisms that could be pushed beyond their physiological limits due to future acidification is the eastern oyster, C. virginica, which provides the basis for an expanding aquaculture industry.  Previous studies have shown that oyster larvae are negatively impacted by acidification, but less is known about what level of acidification initiates a stress response and how well larvae can modulate these mechanisms. Additionally, little is known about potential differences in stress tolerance among different oyster populations. Therefore, larvae were compared between two different reefs within Chesapeake Bay to assess the hypothesis that reefs exposed to lower salinity conditions will be more tolerant to future acidification due to overlap in the cellular mechanisms responsible for osmoregulation and acid-base regulation.

Development and applications of pH glider technology in the Mid-Atlantic Bight

Liza Wright-Fairbanks, Sea Grant Knauss Fellow, NOAA OAP

Currently, productive coastal systems lack vertically-resolved high-resolution ocean carbonate system measurements on timescales relevant to organism ecology and life history. To address this issue, a newly developed deep ISFET (Ion Sensitive Field Effect Transistor)-based pH sensor system was modified and integrated into a Slocum G2 profiling glider. From Spring 2018 to Fall 2019, seasonal pH glider deployments were conducted in Atlantic surfclam (Spisula solidissima) and Atlantic sea scallop (Placopecten magellanicus) commercial management zones in the Mid-Atlantic Bight. Here, we present seasonal cycles and drivers of carbonate chemistry in the Mid-Atlantic Bight based on seasonal glider deployments. Additionally, we discuss the use of glider data in conjunction with larval dispersal models to identify times and locations where shellfish stock may be at high risk of acidification. 

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