35 climatologists, seagrass researchers, and resource managers from universities, the Northwest Indian College, and State and Federal agencies gathered for a workshop titled "The Future of Pacific Northwest Seagrasses in a Changing Climate."
Future of Pacific Northwest Seagrasses in a Changing Climate
Seagrasses provide crucial habitat for fish, birds, and invertebrates and serve as indicators of nearshore ecosystem health. As evidence of its ecological value, eelgrass (Zostera marina), one of six species of seagrass in the Pacific Northwest, is protected by a no-net-loss policy for shoreline development in the State of Washington. Moreover, Washington has set a target of increasing eelgrass habitat in Puget Sound by 20 percent by the year 2020. Near-term seagrass protection and enhancement goals in the Pacific Northwest could be affected by climate-change components that alter nearshore atmospheric, oceanic, and coastal attributes and processes, such as changing temperature, storminess, precipitation, runoff, sea level, upwelling, and ocean acidification. To explore the implications of such changes for seagrass research, restoration, resilience, and adaptation, 35 climatologists, seagrass researchers, and resource managers from universities, the Northwest Indian College, and State and Federal agencies gathered at the University of Washington's Friday Harbor Laboratories January 23–25, 2013, for a workshop titled "The Future of Pacific Northwest Seagrasses in a Changing Climate." The goals of the workshop—cosponsored by the U.S. Geological Survey (USGS), the Washington Department of Natural Resources, the U.S. Environmental Protection Agency, and Washington Sea Grant—were to quantify impacts and mechanisms, discuss the current state of scientific knowledge, and identify critical issues, data gaps, and uncertainties.
The 2½-day workshop began with an introductory talk and question-and-answer session by Guillaume Mauger, a climatologist in the University of Washington's Climate Impacts Group who described Pacific Northwest climate variability, climate change, and uncertainties about future projections out to 2100. The main body of the workshop consisted of six topical sessions about climate-change components important for Pacific Northwest seagrasses. Each session began with a short topical talk by a guest speaker: W. Jud Kenworthy (retired National Oceanic and Atmospheric Administration [NOAA]) spoke about water temperature; Andrew Stevens (USGS) about storminess; Ken Moore (Virginia Institute of Marine Sciences), precipitation and runoff; John Rybczek (Western Washington University), sea-level rise; Francis Chan (Oregon State University), coastal upwelling; and Dick Zimmerman (Old Dominion University) and Justin Campbell (Smithsonian Institution), ocean acidification. The talks were followed by 2 to 3 hours of round-table discussion about implications for seagrasses in coastal estuaries of northern California, Oregon, Washington, and British Columbia and in the inland seas of Puget Sound and the Strait of Georgia (a body of water between Canada's Vancouver Island and British Columbia). Scientific posters displayed in gathering areas plus long lunch breaks and evening social hours fostered informal discussions and interactions among participants.
Workshop attendees agreed that there could be more negative than positive impacts of climate change on Pacific Northwest seagrasses; however, they recognized that certain components could have disproportionate effects. For example, eelgrass, which depends on aqueous carbon dioxide (CO2) as a carbon source, may benefit several-fold from higher seawater CO2 concentrations projected to result from increasing atmospheric CO2. A 1 to 2 degree Celsius (°C) increase in temperature, on the other hand, may have less of an effect because it is projected to occur mainly in winter, when water temperature averages only 8° C. Such an increase would be well within the tolerance range of Pacific Northwest seagrasses.
Although first-order climate-change impacts were the primary focus of the workshop, indirect impacts—such as nutrient-induced algal blooms, sediment runoff from watersheds, cascading effects in the food web, and human interactions—could also affect seagrass resilience and adaptation in a changing climate. Hydrodynamic and ecologic models already under development by several of the workshop participants were recognized as a way to understand the complexity of ecosystem linkages and feedbacks resulting from climate change in the Pacific Northwest.
At the end of the workshop, participants volunteered to coauthor three publications about the workshop and its outcomes:
(1) an executive summary in a citable report series for distribution to general audiences;
(2) a peer-reviewed journal article summarizing workshop discussions and conclusions for the international seagrass research community; and
(3) a peer-reviewed journal article for resource managers, presenting restoration priorities and recommendations for seagrass protection, conservation, and enhancement.