Human activities are altering the chemistry, temperature, and sea level of the world’s oceans and research at Bodega Marine Laboratory seeks to understand how these global environmental changes influence coastal marine ecosystems. Rising CO2 also affects the temperature and chemistry of the ocean, which can have negative impacts on many kinds of marine life. As the ocean absorbs CO2 emissions, the pH of seawater decreases and it becomes more acidic. To understand how ocean conditions are changing, researchers use oceanographic buoy and moored sensor platforms to continuously monitor temperature and pH. Researchers also use shipboard measurements of seawater chemistry with laboratory and field studies to study the biological effects of ocean acidification. Oceanographers also study the changes in the strength of upwelling, and the depth from which waters are brought to the surface. Given that deeper upwelled waters are not only colder but also have lower pH, an increase in upwelling winds alone may result in acidification, or weakening winds may mitigate changes in deepwater chemistry. Experiments on the native oyster (Ostrea lurida) indicate that oyster larvae and juveniles may be quite vulnerable to decreasing pH and changes in the calcium carbonate saturation state.
Bodega Ocean Acidification Research (BOAR)
About 30% of the carbon dioxide added to the atmosphere by human activities has been absorbed by the oceans, driving declines in seawater pH, a phenomenon known as ocean acidification. Ocean acidification may pose a particular threat to shellfish, corals, and similar organisms with calcareous skeletons that are vulnerable to dissolution in acidified waters. In 2008, co-PIs Brian Gaylord (BML/EVE), Tessa Hill (BML/Geology), Ann Russell (Geology), and Eric Sanford (BML/EVE) established the Bodega Ocean Acidification Research (BOAR) program at BML. BOAR is an interdisciplinary research program primarily funded by the NSF and focuses on how changing seawater chemistry impacts ecologically and economically important coastal species in California. BOAR scientists are also members of a broader team of marine researchers collaborating to study ocean acidification along the west coast of the U.S, via an NSF consortium called the Ocean Margin Ecosystems Group for Acidification Studies (OMEGAS). In the past 5 years, these programs have been supported by over $6.2 million in grants ($2.3 million to UC Davis/BOAR), including primary support from the NSF as well as the UC Multi-campus Research Programs and Initiatives (MRPI).
The BOAR program has used a three-pronged approach to study the emerging problem of ocean acidification, including (1) deployment of oceanographic instruments to monitor spatial and temporal changes in seawater chemistry, (2) laboratory culturing experiments to determine impacts of ocean acidification on the early life stages of key coastal species, and (3) field experiments to evaluate potential consequences in the real world.
The ocean monitoring component of BOAR uses shipboard, moored, and onshore instruments to record variation in pH and other environmental conditions. BOAR has also established a partnership with oyster growers and maintains pH instruments at the Hog Island Oyster Company in Tomales Bay. Collectively, these monitoring efforts reveal that episodes of low pH events already occur routinely along the northern California coast. This finding supports growing concern that global trends in ocean acidification may be amplified in coastal upwelling ecosystems, such as the region where BML is centered.
A cornerstone of the BOAR program has been the design, construction, and operation of two sophisticated systems at BML to culture the early life stages of ecologically and economically important species under controlled carbon dioxide and temperature levels. These experiments have examined the effects of acidified waters on the larvae of native oysters, mussels, sea urchins, and other species. This work suggests that ocean acidification poses a particular threat to the early life stages of shellfish (oysters and mussels), and has led to high-profile publications in Proceedings of the National Academy of Sciences, Ecology, Global Change Biology, Journal of Experimental Biology, and other top journals.
A novel component of the BOAR program has been the use of complementary field studies to evaluate the effects of changes in ocean chemistry on species under realistic conditions in the field. This approach is exemplified by BOAR studies of juvenile oysters outplanted to Tomales Bay, and studies of mussel growth replicated along the coasts of California and Oregon.
The BOAR program includes a large training and outreach component. To date, BOAR has trained 8 graduate students, 3 post-doctoral scientists, and 6 research technicians (mostly post-baccalaureate students from UC Davis) working on ocean acidification projects. With support from the UC MRPI program, BOAR trainees also benefit from interactions with colleagues working on ocean acidification at UC Santa Barbara and Scripps Institution of Oceanography (UC San Diego). BOAR scientists are members of the California Current Acidification Network (C-CAN), a partnership among academic scientists, policymakers, and the aquaculture industry for coordinated monitoring and outreach. BOAR scientists have been very active in communicating their findings to the public via a variety of interviews and news stories (TV, radio, print) that are archived on the BML website.
Climate Change in Marine Systems
Scientists at BML are engaged in researching many other aspects of climate change, which can be grouped broadly into oceanographic and ecological studies as well as in the context of habitat restoration and invasive species.
Tessa Hill’s Lab uses paleoceanographic and geochemical records to study the forcing mechanisms and feedbacks of the Earth’s climate during the past 1 million years. This research uses stable isotopes, trace elements, and other proxies in sediment cores collected from the ocean floor to reconstruct past changes in ocean temperature. In addition, the Hill Lab has measured stable isotopes in long-lived deepwater corals to reconstruct more recent changes in ocean temperature and nutrients over the past several hundred years. Additional studies focus on samples of microfossils from sediment cores to understand how rapid climate change has altered biological assemblages of invertebrates in the past.
John Largier has been leading the development of the Bodega Ocean Observing Node (BOON) – a regional effort to monitor, index, and understand the ocean environment in the vicinity of Bodega Bay (i.e., between San Francisco Bay and Point Arena). BOON delivers real-time data and analyses on currents, temperature, salinity, chlorophyll, turbidity, and wind that are used by a variety of researchers, mariners, ocean users, and environmentalists. This is part of a regional association (CeNCOOS) and data are increasingly used to better understand and manage environmental resources (e.g., in design of marine protected areas) and environmental quality (e.g., in mapping regional impact of San Francisco Bay outflow). John Largier and his graduate student Marisol García-Reyes have recently studied historical wind and sea surface temperature data to document modern changes in wind-driven upwelling that have occurred along the California coast during the past 3 decades. Largier also served as the chair of the scientific advisory council that authored a 2010 report regarding climate change impacts on marine ecosystems in northern California (prepared for the Gulf of the Farallones and Cordell Bank National Marine Sanctuaries).
Ecological Climate Change Studies
Changing climates inevitably raise the pervasive ecological and evolutionary question of whether populations are capable of persisting, either through dispersal, plasticity, or shifts in the genetic composition of populations. Bodega Marine Laboratory’s strategic location at the center of many ranges of intertidal invertebrates, along with its superb culturing facilities and access to rocky shores, makes it an ideal place to test hypotheses about the responses of marine organisms to changing climates.
Eric Sanford’s Lab studies the potential for temperature change to influence marine communities through geographic range shifts and altered species interactions. Recent experiments document how temperature stress influences the interaction between a keystone predator (the Ochre Sea Star) and its mussel prey. The Sanford Lab has also been studying the hotly debated question of whether evolutionary change (adaptation) might buffer natural populations against the threats of climate change. In particular, laboratory selection experiments have tested whether populations of tidepool crustaceans and sea urchins harbor sufficient genetic variation to adapt to environmental change.
Ph.D. student Morgan Kelly (collaborating with Eric Sanford and Rick Grosberg) examined the impacts of thermal stress on population persistence and range limits in the high intertidal copepod Tigriopus californicus. Despite extremely limited dispersal potential, T. californicus ranges from Baja California northward through the Aleutian Islands. In a series of selection experiments that included populations spanning much of the core of T. californicus’ range, we showed that thermal maxima differed widely from population-to-population, and that all populations had a limited capacity to respond to selection for increased thermal tolerance (Kelly et al. 2011). Indeed, most populations were already at, or near, their thermal maxima, suggesting that increasing temperatures could drive many populations to extinction, especially given the limited gene flow that characterizes this species. This work garnered substantial media attention, and was featured on both NPR and ABC television.
These limits may be driven by a lack of additive genetic variance, or costs of increased tolerance, manifest in fitness trade-offs with other traits. In Kelly et al. (2013), we aimed to distinguish between the variance and trade-off hypotheses, and showed that selection for increased thermal tolerance across 6 populations of Tigriopus actually produced a small positive effect on five fitness-related traits, rather than the expected negative responses. The effects of selection on correlated traits also differed by population, indicating that the genetic basis of thermal adaptation varies across populations. Taken together, these results suggest that the limited capacity to respond to climate change in Tigriopus, and perhaps many other species with limited gene flow, reflects a paucity of genetic variation, and not genetically based fitness trade-offs.
Unlike Tigriopus, the pink volcano barnacle Tetraclita rubescens, appears to be expanding its range northward as seawater temperatures increase. Is this expansion due to a shifting climate envelope or adaptation at the northern range limit? Mike Dawson (UC Merced), Eric Sanford (BML), and Rick Grosberg (UC Davis-BML) completed a comprehensive analysis of rangewide genetic structure in the volcano barnacle Tetraclita rubescens, which has expanded its range nearly 200 kms northward in the last 2-30 years (Dawson et al. 2010). Nuclear and mitochondrial data both show that T. rubescens is panmictic throughout its range spanning >2000 kms of coast, and that there is abundant variation in all populations, even the most recently established ones. We concluded that genetic swamping by locally maladaptive alleles has limited the capacity of T. rubescens to respond to novel selection pressures at its range boundary, and that the ongoing range expansion is likely due to changes in the latitudinal thermal gradient.
A variety of other recent projects at BML have sought to understand how climate change is influencing marine communities. For example, Susan Williams and graduate student Cascade Sorte combined field and laboratory studies to demonstrate that increasing ocean temperatures favor invasive invertebrate species in Bodega Harbor. Steven Morgan’s Lab has been using natural communities on rocky intertidal boulders as a model system to investigate how variation in temperature influences species interactions and distributions.
The Hill lab at BML aims to understand climate change in the past and present ocean, spanning geologic (past 1 million years) to human timescales (past 100 years, and future). We are interested in large-scale ocean processes (e.g., circulation changes) down to bays, estuaries, and coastal environments. We approach this research by using microfossils (literally, very small fossils!) and corals to determine rates and magnitude of climate change, the response and adaptation of species to environmental change, and the impact of ocean acidification on marine ecosystems. This research is motivated by a need to understand the Earth’s climate system to predict future consequences of anthropogenic climate change.
There are several ongoing projects in the Hill lab and significant accomplishments over the past five years. Work on sediments from the California margin has involved several BML, Geology and Ecology graduate students and resulted in peer-reviewed publications and presentations at national and international conferences. In particular, our work has documented how rapidly marine species respond to temperature and oxygenation change in the past 20,000 years. This research is supported by the National Science Foundation via grants to Professor Hill and collaborators at UC Santa Barbara and UC Davis (A. Russell). This work is also the subject of a NSF Early Career Award to Professor Hill, which will support the expansion of this research and the development climate change curricula for 6th grade classrooms over the next 5 years.
The Hill lab also utilizes deep-sea corals – most of them from the California coast – to reconstruct climate events over the past several hundred years. Deep sea “bamboo” corals grow a skeleton with annual bands that can be used to reconstruct environmental change, much like ‘tree rings’ on land. Professor Hill and postdoctoral scholar Michelle LaVigne (now Assistant Professor at Bowdoin College) have published three papers on this topic, aimed at using bamboo corals to reconstruct temperature, nutrient, and productivity changes over the past several hundred years. This work is supported by grants from the National Science Foundation and the National Oceanographic and Atmospheric Administration.
Restoration of Native Olympia Oysters Under Climate Change
An important focus for Ted Grosholz involves the ecology and potential for restoration of native Olympia oysters Ostreola conchaphila (previously Ostrea lurida) in western estuaries. Estuaries in California have been heavily impacted by human activities that have resulted in substantial loss of habitat, invasion by non-native species, inputs of sediments and contaminants and other stressors that have resulted in substantial declines in ecosystem function. One important approach to restoring these functions is the restoration of native species. Historically, native oysters likely provided the same ecosystem services that have been documented for native oysters in the eastern U.S. including the provision of habitat for native invertebrates and fishes and improving local water quality. There is now substantial interest on the part of many local, state, and federal agencies and natural resource managers in improving the health of California estuaries by restoring native oyster populations.
The Grosholz lab’s research program now addresses climate change in the context of both limiting populations of native Olympia oysters as well as efforts to restore their populations. With funding from the NOAA/NERR Science Collaborative, and in collaboration with partners from San Francisco Bay NERR (Matt Ferner), Elkhorn Slough NERR (Kerstin Wasson) and UCD/SERC (Chela Zabin), they are investigating the effects of climate change variables on the future of restoration of this important foundation and fishery species in San Francisco Bay and Elkhorn Slough, CA. They are explicitly testing the influence of multiple climate change variables including sea surface and air temperatures, dissolved oxygen (hypoxia), and salinity on native Olympia oysters in both the lab and field settings. The Grosholz lab has conducted lab experiments examining the influence of temperature, dissolved oxygen and salinity extremes on native oysters. They have also quantified these variables and others in field plots at multiple sites in SF Bay and Elkhorn Slough. The project will also develop a targeted set of decision tools for user groups involved with oyster restoration using substantial input from these groups in tool development. This work breaks new ground by examining multiple climate change variables by parameterizing experimental levels, durations and delays between stressors based on actual time series experienced in the field.
An additional focus of the Grosholz lab’s work also involves large-scale restoration projects involving simultaneous restoration of native oyster and eelgrass habitat. This project is funded by the California Coastal Conservancy and involves partnerships with San Francisco State University (Kathy Boyer),UCD/SERC (Chela Zabin), USGS (Susan de la Cruz), PWA (Jeremy Long), Environcorp (Bud Abbott), and CA Coastal Conservancy (Marilyn Latta). They are conducting restoration in plots distributed across several acres at two sites in SF Bay, an East Bay site at Eden Landing and a Marin County site on TNC lands. At these sites, both eelgrass and native Olympia oyster restoration is the goal using a variety of experimental recruitment substrata to encourage native oyster recruitment and experimental plantings of eelgrass to enhance growth of eelgrass beds. These are conducted explicitly to test methods for effectiveness and to understand the potential impacts and synergies of restoring these two habitats concurrently. An additional goal is to also understand the potential for the oyster recruitment structures to reduce wave energy and protect shorelines from erosion.
- National Estuarine Research Reserve System (NERRS) Science Collaborative Project
- San Francisco Bay Living Shorelines Project
NSF Supported Climate Change Facility
In addition to existing ocean acidification facilities constructed by the BOAR group, BML was successful in obtaining NSF FSML support to establish a climate change facility that will allow researchers and students to simultaneously control multiple environmental variables (including CO2) with precision at levels typical of real-world climate change scenarios. Changes in climate can have broad-scale effects on ocean ecosystems, altering the movement of organisms and disease, fisheries productivity, or the sensitivity of food species to disease and pollution. Understanding the potential effects of climate change on resources needed to sustain global, national and state economies is the critical issue of our time.