Posted on EPOCA: 24 Jul 2011
Led by the research groups of Brian Gaylord, Tessa Hill, Ann Russell, and Eric Sanford, the Bodega Ocean Acidification Research (BOAR) consortium is examining spatial and temporal changes in seawater chemistry and the impacts of this variability on the ecology, physiology, and biomechanics of critical nearshore marine invertebrates. Documented, ongoing declines in pH and carbonate saturation state are thought to pose a particular threat to organisms that synthesize calcium carbonate shells and skeletons, which are vulnerable to dissolution in acidified waters.
We are using a three-pronged approach to address this issue, including 1) modern ocean monitoring and past ocean reconstructions to quantify changes in seawater properties over multiple timescales, 2) laboratory experiments to determine impacts on larval, juvenile, and adult stages, and 3) field outplants to evaluate potential consequences accruing in the real world. In conducting this work, we are exploiting the fact that our group is centered at Bodega Marine Laboratory (BML) within one of the most intense upwelling centers in the world. Waters rising from depth at our location bathe organisms in seawater characterized by geochemical signatures (low pH and reduced carbonate saturation state) resembling those expected over global scales decades in the future.
Our research is also facilitated by a suite of laboratory and field instrumentation available for the study of ocean acidification:
Oceanographic data are collected at two permanent oceanographic moorings, one located in open-coast waters offshore of BML, and a second within a nearby estuary (Tomales Bay). These moorings are outfitted with SAMI-pH and SAMI-pCO2 sensors that together enable full characterization of the carbonate system. These sensors sample with hourly resolution, with measurements from the BML mooring telemetered directly to a publicly accessible online database, maintained by the Bodega Ocean Observing Node (BOON). Monthly in-situ sampling, accomplished along two oceanographic transects using BML’s 42-foot vessel, the R/V Mussel Point, provides additional discrete samples analyzed for dissolved inorganic carbon (DIC), total alkalinity (TA), pH, nitrate, and carbon and oxygen isotopes.
The BOAR Culturing Facility enables marine invertebrate larvae, juveniles, and adults to be raised under rigorously controlled, altered seawater conditions. The system consists of two temperature-regulated seawater tables that bathe multiple glass jars used to culture organisms. The culture vessels are supplied with seawater maintained in equilibrium with air containing specified CO2 concentrations, holding the water’s pH and carbonate saturation state at prescribed levels.
The Trace Elemental Analytical Facility, consisting of an Inductively Coupled Plasma Optical Emissions Spectrometer (ICP-OES) allows for quantification of minor and trace metals in the shells and skeletons of marine organisms. These metals form part of a suite of geochemical proxies used to develop records of past seawater temperature change in local waters from material contained in sediment cores. We also have regular access to Isotope Ratio Mass Spectrometers (IRMS) and ICP-MS instruments (Agilent Quad and Thermo Scientific Element 2), for analysis of stable isotopes and metals in seawater and hard parts of marine organisms. These metals include uranium, a promising tracer of changes in seawater pH through time.
A Taylor-Couette cell provides a means of assessing the strengths of the calcium carbonate shells and skeletons of marine larvae exposed to acidified seawater. Although direct testing of larval structures is difficult due to their tiny dimensions, the mechanical integrity of these structures can be examined by imposing known intensities of hydrodynamic shear stress. For larger (e.g., adult) shells, we employ an Instron materials testing device to quantify the strength of calcified structures.
Research efforts to date have focused primarily on two coastal “foundation species” – species that play disproportionately important roles in communities by providing crucial habitat, or by maintaining essential ecosystem traits. Ostrea lurida, the Olympia oyster, is native to California estuaries and can exert a strong influence on water quality through its filtering activities. The California mussel, Mytilus californianus, is not only a competitive dominant on exposed rocky shores, but also provides habitat for a vast array of fauna that live in the interstices of its beds. We are working to dissect ecological impacts of ocean acidification on several additional taxa of interest as well.
UC DAVIS Bodega Marine Laboratory, 18 July 2011. Web site.