Student and Early Career Scientist Webinar Series
April 20, 2021 at 1 PM ET
Presented by Jennie Rheban, Woods Hole Sea Grant and Parker Gasset, Maine Sea Grant
More information forthcoming.
May 13, 2021 at 1 PM ET
Presented by Kelly McGarry, University of Connecticut
More information forthcoming.
June 3, 2021 at 1 PM ET
Presented by Chris Hunt, University of New Hampshire
More information forthcoming.
Ocean Acidification and Warming Act Synergistically to Reduce Cardiac Performance and Increase Disease Susceptibility in Juvenile American Lobster
November 10, 2020
Amalia Harrington, Maine Sea Grant, University of Maine
Increased greenhouse gas emissions have caused rapid ocean warming (OW) and reduced ocean pH via acidification (OA). Both stressors will likely impact marine crustaceans, but they are often examined in isolation. We conducted an environmental stressor experiment to understand how exposure to current summer conditions, OW only, OA only, or both acidification and warming (OAW) differentially influence the thermal physiology and immune response of juvenile American lobster, Homarus americanus. Following a 42-d exposure to these stressor treatments, cardiac performance was assessed during an acute thermal stress, and lobsters were subjected to a subsequent 21-d pathogen challenge with Aerococcus viridans var. homari, the causative agent of gaffkemia. Lobsters exposed to OAW had significantly lower Arrhenius Break Temperatures (ABT; indicator of thermal limits of capacity) when compared to lobsters from all other treatments, suggesting these stressors act synergistically to reduce physiological performance. Individuals from the OW only and OAW treatments also had significantly lower total hemocyte counts (THCs; indicator of immune response) and showed a reduced median time to death (by up to 5 d sooner) post A. viridans injection compared to lobsters exposed to current summer conditions. Moreover, nearly twice as many lobsters exposed to OAW lost at least one claw during the pathogen challenge compared to all other treatment groups, potentially increasing the risk of mortality due to secondary infection. Together, these results suggest that predicted end-century OAW will impact the physiology and immune response of juvenile H. americanus, potentially influencing successful recruitment to the fishery.
The Effects of Ocean Acidification and Parental Environment on Shell Formation in Larval Eastern Oysters
January 27, 2021
Elise McNally, Northeastern University
Ocean acidification (OA) threatens shellfish production because it reduces the availability of carbonate ions in seawater, which calcifying organisms use to build their shells or skeletons. Eastern oysters (Crassostrea virginica) are ecologically and economically important species that generally exhibit negative responses to OA. Larval oysters are particularly vulnerable because of rapid rates of calcification and increased exposure of crystal nucleation sites to seawater. Changes in shell growth and morphology could result in decreased larval survival and subsequently decreased recruitment. Most previous studies have assessed the impacts of OA on larvae with parents naïve to the effects of OA. However, the environment that parents experience during reproductive conditioning could play a role in determining larval responses to OA through non-genetic inheritance mechanisms. We examined the effects of parental exposure to OA on Eastern oyster larval shell growth, shell morphology, and survival. We produced larvae from control-exposed and OA-exposed parents. Larvae from each cross were grown under control and OA conditions for three days. Parental exposure to OA increased the resilience of oyster larvae grown under OA conditions. OA-exposed larvae with OA-exposed parents exhibited faster growth rates and larger shells than OA-exposed larvae with control-exposed parents. Parental OA exposure was not sufficient to offset the effects of OA on biomineralization or survival in this experiment. However, these results suggest that parental exposure to OA mitigates some of the negative impacts of OA on Eastern oyster larvae and that oysters have the capacity to acclimate to OA.
Understanding Net Ecosystem Metabolism and Carbonate Chemistry at Near Coral Reef Ecosystems Using Moored Autonomous pCO2 Systems: Lessons From Puerto Rico and Florida
February 25, 2021
Melissa Melendez, Ph.D., University of Hawai'i at Manoa
Time series from open ocean fixed stations have robustly documented secular changes in carbonate chemistry and long-term ocean acidification (OA) trends as a direct response to increases in atmospheric carbon dioxide (CO2). However, few high-frequency coastal carbon time series are available in reef systems, where most affected tropical marine organisms reside. Seasonal variations in carbonate chemistry at Cheeca Rocks (CR), Florida, and La Parguera (LP), Puerto Rico, are presented based on 8 and 10 years of continuous, high-quality measurements, respectively. The autonomous carbonate chemistry and oxygen observations are used to examine a mass balance approach using a 1-D model to determine net rates of ecosystem calcification and production (NEC and NEP) from communities close (<5km) to the buoys.
High-frequency carbonate system data for these two multi-year time series show different seasonal amplitudes, offering insight into differing local biogeochemical processes. The current metabolic status of LP and CR, based on our results, are net dissolutional and net heterotrophic on the annual cycle. Results show that the seasonal cycle of carbonate chemistry cannot be attributed to temperature dynamics but rather reflects the combined effects of ecosystem processes. Respiration, particularly in late summer and fall, appears to be an additional source of CO2 to the systems and can make calcification more energetically demanding as well as increase dissolution rates during this time of the year. This work contributes high-quality observations of ecosystem response and water chemistry under unique natural conditions. High-frequency data provided by these and similar operational systems can be used to develop early warning capabilities needed to identify and predict ecological trophic fluctuations.
The Consequences of Ocean Warming and Acidification for the Atlantic Sea Scallop Fishery
March 8, 2021
Lousie Cameron, Woods Hole Oceanographic Institution
The Northwest Atlantic shelf is expected to experience accelerated rates of ocean warming and acidification over the 21st century. Atlantic sea scallops inhabit the Northwest Atlantic shelf from Cape Hatteras to the Gulf of Maine and support one of the most profitable fisheries in the United States. Scallops have large calcite shells that may be vulnerable to dissolution under future ocean acidification. Here, I will present the results from mesocosm studies and field surveys designed to investigate the effects of ocean acidification and warming on Atlantic sea scallop shell and meat properties. I will also discuss my ongoing work to develop a spatially explicit model that will predict sea scallop vulnerability to ocean acidification across their rotational management areas using historic carbonate chemistry data and industry-based cruises.