NECAN Sea Grant Webinar Series
The purpose of this webinar series is to highlight four projects funded through NOAA Sea Grant following the release of the NECAN paper published in Oceanography Magazine in 2015, "Ocean and Coastal Acidification off New England and Nova Scotia." The ocean and coastal acidification research and monitoring priorities which were defined in this paper were used by Sea Grant in a 2016 request for proposals. Submissions from University of Connecticut, University of Maine, and two from Stony Brook University were chosen and funded. These webinars will highlight each of these projects, their successes, challenges, and results.
The Unusual Sensitivity of Northern Sand Lance, a Keystone Forage Fish, to Acidification and Warming
September 10, 2019
Hannes Baumann, PhD., University of Connecticut
Sand lance species play a key ecological role in most temperate to polar shelf ecosystems of the northern hemisphere, where they channel planktonic productivity upwards to higher trophic piscivores such as whales, seabirds, cod, and tuna. However, they have remained unstudied with respect to their sensitivity to predicted future CO2 levels in the ocean. For the past three years (2016 - 2018), we have sampled and spawned with northern sand lance (Ammodytes dubius) from Stellwagen Bank National Marine Sanctuary and subsequently reared their embryos under factorial CO2 x temperature conditions to hatch and early larval stages. Our results were striking, in all years, high CO2 conditions severely reduced embryo survival up to 20-fold over controls, with strong synergistic reductions under combined high CO2 and temperature conditions. High CO2 also delayed hatching, reduced remaining endogenous energy reserves at hatch, and in combination with higher temperatures, reduced embryonic growth. Indeed, given the observed effect sizes, northern sand lance might be the most CO2 sensitive fish species tested to date. This webinar will give a first-hand account of our work on sand lance, its results and implications for temperate to polar ecosystems, which may be among the most vulnerable to marine climate change.
Gene Regulatory Response to End-Century Temperature and pCO2 in Post-Larval American Lobster
October 9, 2019
Richard Wahle, PhD, University of Maine and Maura Niemisto, Bigelow Laboratory for Ocean Sciences
Anthropogenic carbon released into the atmosphere is driving rapid, concurrent increases in temperature and acidity across the world's oceans, most prominently in northern latitudes. The geographic range of the iconic American lobster (Homarus americanus) spans a steep thermal gradient and one of the most rapidly warming ocean environments. Understanding the interactive effects of ocean warming and acidification on this species' vulnerable early life stages is important to predict its response to climate change on a life stage-specific and population level. This study investigated the interactive effects of ocean warming and acidification on the gene expression response of the planktonic post-larval lobster from southern New England. Using a full factorial experimental design, lobsters were raised in ambient and elevated pCO2 concentrations (400 ppm, 1200 ppm) and temperatures (16°C and 19°C). Overall, we identified 1,108 transcripts that were differentially expressed across treatments, several of which were related to stress response and shell formation. When temperature alone was elevated (19°C), larvae downregulated genes related to cuticle development; when pCO2 alone was elevated (1200 ppm), larvae upregulated chitinase as well as genes related to stress response and immune function. The joint effects of end-century stressors (19°C, 1200 ppm) resulted in the upregulation of those same genes, as well as cellulase, and the downregulation of calcified cuticle proteins, and a greater upregulation in genes tied to immune response and functioning. These first results of the impact of varying conditions on larval lobster gene expression suggest the existence of mechanisms to respond to stressors resulting from a rapidly changing environment.
Resilience to Ocean Acidification in Commercially Important Bivalves: Physiological Costs and Underlying Molecular Processes
November 13, 2019
Michelle Barbosa and Caroline Schwaner, Stony Brook University
As we near the end of the century, the fate of our marine environments becomes increasingly worrisome. With increasing carbon dioxide emissions, the pH of the ocean will decrease and thus have profound impacts on ocean chemistry. Ocean acidification (OA) has been predicted to have variable, but often adverse, impacts on the fitness of calcifying species. Bivalve species are considered to be among the most threatened taxa under the predicted end-of-the-century climate. In this presentation, we describe some of the physiological costs associated with resilience to OA and begin to uncover the molecular processes underlying resilience in bivalves. Our investigations into the effects of OA on bivalves have demonstrated differences in inter-species susceptibility to acidification and multiple stressors. Our study found contrasting patterns in growth for hard clam (Mercenaria mercenaria) and eastern oyster (Crassostrea virginica) larvae. Most strikingly, larval hard clams and eastern oysters are particularly sensitive to major bacterial pathogens under the predicted future climate. This vulnerability could facilitate the loss of ecologically and economically important species. To understand potential mechanisms for persistence of these species, a greater insight into the mechanisms and molecular processes underlying resilience is needed. This knowledge could be critical to determining the extent to which bivalve stocks are at risk in future climate conditions. Investigations in the potential for genetic bases for resilience to OA has uncovered many genes potentially acting in concert to affect the survival of the individual. Combining both RNAseq and RADseq technologies, our studies have demonstrated both changes in gene expression and selection for key single nucleotide polymorphisms (SNPs) underlying resilience to OA. These molecular features may be important for orchestrating survival in acidified seawater. The identification of these features is vital for selecting traits necessary for the persistence of aquaculture stocks under OA.
Population Differences in Resilience to Climate Change: Responses of Blue Mussels to Ocean Acidification
December 12, 2019
Dianna Padilla, PhD., Stony Brook University
Most research to date suggests that bivalve molluscs are particularly sensitive to the impacts of ocean acidification (OA). But, at present we do not know whether differences among local environmental conditions has selected for animals with different sensitivities to stressors. Similarly we do not know whether responses to environmental stressors are phenotypically plastic, allowing animals with broad physiological tolerances to be robust to environmental stress. Blue mussels, Mytilus edulis, were collected from sites around Long Island Sound (LIS) to test whether mussels from more stressful environments are more resilient to the impacts of OA as larvae, juveniles, as well as across generations. We found that mussels from different populations show different responses to OA in larval survivorship and juvenile growth. Interestingly, although there were differences among populations in some traits, there was no effect of OA (e.g., time to metamorphosis, shell structure, thickness and breaking strength). Mussels reared for a second generation under OA stress indicates that in some cases robustness to OA stress was masked in the first generation but was revealed in the second generation. As a whole, these results suggest that there is variation in both genetic and phenotypically plastic robustness to OA stress in blue mussels.