Originally posted at http://seagrant.mit.edu/press_releases.php?nwsID=656

MIT Sea Grant has selected four research projects for funding from our annual request for proposals. The four projects are described below.

Making Sense of the Variability of Coastal Ocean Acidification: Potential Long-Term Impacts on the Oyster Aquaculture Industry
Robert Chen, University of Massachusetts Boston

The project seeks to determine the potential impacts of ocean acidification on aquaculture practices of the Eastern oyster, Crassostrea virginica. Seawater has decreased by 0.1 pH units and may decrease by another 0.3 by 2100 threatening the health of shelled organisms. Extremely low aragonite saturation events have been found to have the most impact on the health and survival of oysters. Chen and colleagues will characterize the variability in pH and pCO2 continuously in Duxbury and Barnstable Harbor (hatchery) and its causes. Two ocean acidification monitoring systems will be constructed and deployed. The Endurance Ocean Acidification System (EOAS) will be deployed permanently at the Duxbury Harbor Town Pier. The Pioneer Ocean Acidification System (POAS) will be deployed at a variety of coastal sites for periods of 6-12 months, initially at Barnstable Harbor. pH of surface seawater will be measured continuously (every 15 min) using a spectrometric method and calibrated using discrete seawater measurements. pCO2 will be measured using an equilibrator and a LI-COR infrared CO2 detector and calibrated using reference gases. That data will then be used to predict future levels and durations of pH, pCO2 and aragonite saturation. Characterization of future ocean acidification variability over short and long terms can inform the oyster aquaculture industry to develop resilient and sustainable aquacultural practices. Researchers plan to work closely with stakeholders to determine potential impacts on the aquaculture industry. Data from this project will be used to inform the Massachusetts Shellfish Initiative.

Measuring Acid/Base Chemistry in the Extrapallial Fluids of New England’s Commercially Important Mollusks to Explore their Differential Responses to Ocean Acidification.
Justin Ries, Northeastern University

This project seeks to quantify impacts of ocean acidification (OA) and warming on extrapallial fluid pH (EPF-pH) of three commercially important mollusk species: eastern oyster, Atlantic sea scallop, and blue mussel. Previous research by Ries has shown that mussels exhibit greater resilience to OA than oysters and scallops and that control over calcification site pH can be an important factor controlling a species’ response to OA. Ries and et al. propose to apply a recently developed pH-microelectrode approach to quantify mollusk EPF-pH response to combined OA and warming. Three hypotheses will be tested: are more OA-resilient mussels able to maintain baseline EPF-pH at levels above those of less OA-resilient oysters and scallops; is the EPF-pH of mussels less impacted by reductions in seawater pH than EPF-pH of scallops and oysters; and, lastly, do temperature and , and OA stress synergistically impact calcification in all three species. Controlled 90-day laboratory experiments will be conducted to quantify effects of ocean acidification (pCO2 = 400, 900, 1800 µatm) and warming (optimal + 5 ºC) on EPF-pH, calcification rate, and physiological conditions of three commercially important mollusk species. Linking EPF-pH-control to calcification response to combined OA and warming may enable rapid assessment of relative vulnerability/resilience to these stressors at species, population, and individual levels via relatively easy-to-execute EPF-pH measurements. Likewise, results from this study could be used by shellfish hatcheries to identify high-EPF-pH individuals to selectively breed for OA resistance.

Quantifying Coastal Ocean Acidification Impacts on Estuarine Nitrogen Removal
Robinson W. Fulweiler, Boston University

This research seeks to determine the effect of coastal acidification on sediment denitrification. Sediment denitrification provides a critical ecosystem service by removing nitrogen from estuaries thereby combatting eutrophication. The effect of acidification on sediment denitrification is unknown. However, research on terrestrial ecosystems demonstrates pH as a regulator of denitrification: as pH decreases denitrification efficiency also decreases. Coastal acidification could inhibit denitrification which would decrease water quality and have significant impacts on economically important fauna (e.g., commercial/recreational fisheries, oyster aquaculture). Fuleiler and colleagues will use a multipronged biogeochemical-molecular approach to meet our objectives in the field and laboratory. Initial research will include a survey of the active microbial community in estuarine sediments to characterize the potentially active sediment microbial community under different pH regimes. Researchers will couple rates of sediment denitrification (i.e., N2 and N2O fluxes) to the activity of key functional genes (nirS, nirK, nosZ) and the denitrifying community at sites under different pH regimes. There will also be an experimental component, where researchers will alter water column pH to directly test coastal acidification impacts on sediment denitrification and the active microbial community. This research will ultimately help to improve water quality by providing novel insight on the impact of coastal acidification on sediment denitrification.

Magnetic Induction (MI) Wireless Underwater Data Communications: Bottom-to-Surface Ocean Temperature Monitoring 
Chathan Cooke, MIT

This project seeks to establish base-line technology for magnetic induction (MI) wireless communications in the underwater environment. Reliable capability to communicate from the underwater sensor station to a surface vessel for downloading of stored time series data is a key component that enables consistent highly cost-effect data acquisition. Researchers will quantify the MI wireless channel characteristics and design source and receiving antenna to better match to the MI channel properties. A water-tight temperature measurement demonstration system will be designed, constructed and tested to validate wireless MI data communications. The demonstration will also establish the viability for economical automated data communications using MI from seafloor data acquisition to a surface vehicle on a periodic collection basis. Changes in ocean temperatures have been shown to have strong effects on fish habitat use. Accurate, consistent and timely monitoring of ocean temperatures is of great importance to fisheries surveys and assessments, and its implications for sustaining resilient coastal communities and their economics. By removing most of the human at-sea time we greatly enhance the practicality to monitor more sites on a long-term basis.