Sensitivity of larval and juvenile sand lance Ammodytes dubius on Stellwagen Bank to predicted ocean warming, acidification and deoxygenation
Hannes Baumann, Marine Sciences, University of Connecticut (860-405-9297); David Wiley, Stellwagen Bank National Marine Sanctuary (781-545-8026); Page Valentine, U.S. Geological Survey (508-457-2239); Les Kaufman, Marine Program, Boston University (617-353-5560); and Scott Gallager, Woods Hole Oceanographic Institution (508-289-2783)
Warming, acidification and deoxygenation resulting from human activity are together affecting marine ecosystems, yet the combined effects of these stressors on marine species remain poorly understood. The major concern is that their combined impact could be greater than the sum of each stressor, i.e., synergistically negative, but these crucial empirical data are currently lacking for all but a very few model species. This knowledge gap currently limits the ability to predict the nature and direction of impending changes in marine ecosystems. In temperate North Atlantic ecosystems, sand lances (Ammodytes spp.) are key forage fish. In the Stellwagen Bank National Marine Sanctuary, their presence is a major reason for the seasonal abundance of iconic predators such as bluefin tuna, cod, sea birds and humpback whales. Despite their importance for the ecosystem, there are no empirical data on the sensitivity of A. dubius to the threats of warming, acidification and hypoxia – individually or in combination. No study to date has specifically evaluated the vulnerability of multiple life stages of fish to multiple stressors. Beyond collecting new data on an important, previously untested species, however, this project's approach has further scientific merit, because sand lance occupy a different habitat (coastal shelf) and has a different spawning season (winter) than all previously studied fish species. This sets up a so far lacking, but potentially highly insightful, contrast between the sensitivity of nearshore forage fish species and more shelf-based species like sand lance. It has been hypothesized but never explicitly tested that the sensitivity of marine organisms to elevated carbon dioxide levels increases with decreasing environmental variability, i.e., from nearshore to ocean shelf to open ocean.
Baumann and his colleagues will quantify the sensitivity of a key forage fish in the Northwest Atlantic to the individual and combined effects of the major factors comprising the ocean climate change syndrome: warming, acidification and deoxygenation. They will rear embryos of Northern sand lance A.dubius through larval and early juvenile stages in a purpose-built factorial system at different factorial combinations of temperature × carbon dioxide × oxygen. The project has three objectives: quantify individual and combined effects of temperature × carbon dioxide (year 1) and temperature × carbon dioxide × dissolved oxygen (year 2) on A. dubius growth and survival; characterize the swimming behavior of A. dubius larvae that have been reared under combinations of elevated temperature × carbon dioxide; and quantify carbon dioxide, pH and dissolved oxygen variability in benthic waters on Stellwagen Bank through bottle collections and short-term sensor deployments to take advantage of the winter sampling.
This research will benefit resource managers and coastal communities that depend directly or indirectly on this marine resource (e.g., recreational fishing, whale watching). Importantly, if sand lance are found to be particularly sensitive to acidification and/or warming and/or deoxygenation, this needs to be strongly communicated to those who currently advocate for starting a commercial fishery for this species. As a key forage species that structures marine food webs, information on sand lance sensitivity to marine climate change is essential for the planning of resilient coastal economies.