White
Meredith M.
White
Meredith M.
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ArticleProjecting ocean acidification impacts for the Gulf of Maine to 2050: new tools and expectations(University of California Press, 2021-05-13) Siedlecki, Samantha A. ; Salisbury, Joseph E. ; Gledhill, Dwight K. ; Bastidas, Carolina ; Meseck, Shannon L. ; McGarry, Kelly ; Hunt, Christopher W. ; Alexander, Michael A. ; Lavoie, Diane ; Wang, Zhaohui Aleck ; Scott, James D. ; Brady, Damian C. ; Mlsna, Ivy ; Azetsu-Scott, Kumiko ; Liberti, Catherine M. ; Melrose, D. Christopher ; White, Meredith M. ; Pershing, Andrew J. ; Vandemark, Douglas ; Townsend, David W. ; Chen, Changsheng ; Mook, Bill ; Morrison, J. RuairidhOcean acidification (OA) is increasing predictably in the global ocean as rising levels of atmospheric carbon dioxide lead to higher oceanic concentrations of inorganic carbon. The Gulf of Maine (GOM) is a seasonally varying region of confluence for many processes that further affect the carbonate system including freshwater influences and high productivity, particularly near the coast where local processes impart a strong influence. Two main regions within the GOM currently experience carbonate conditions that are suboptimal for many organisms—the nearshore and subsurface deep shelf. OA trends over the past 15 years have been masked in the GOM by recent warming and changes to the regional circulation that locally supply more Gulf Stream waters. The region is home to many commercially important shellfish that are vulnerable to OA conditions, as well as to the human populations whose dependence on shellfish species in the fishery has continued to increase over the past decade. Through a review of the sensitivity of the regional marine ecosystem inhabitants, we identified a critical threshold of 1.5 for the aragonite saturation state (Ωa). A combination of regional high-resolution simulations that include coastal processes were used to project OA conditions for the GOM into 2050. By 2050, the Ωa declines everywhere in the GOM with most pronounced impacts near the coast, in subsurface waters, and associated with freshening. Under the RCP 8.5 projected climate scenario, the entire GOM will experience conditions below the critical Ωa threshold of 1.5 for most of the year by 2050. Despite these declines, the projected warming in the GOM imparts a partial compensatory effect to Ωa by elevating saturation states considerably above what would result from acidification alone and preserving some important fisheries locations, including much of Georges Bank, above the critical threshold.
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ArticleEarly exposure of bay scallops (Argopecten irradians) to high CO2 causes a decrease in larval shell growth(Public Library of Science, 2013-04-15) White, Meredith M. ; McCorkle, Daniel C. ; Mullineaux, Lauren S. ; Cohen, Anne L.Ocean acidification, characterized by elevated pCO2 and the associated decreases in seawater pH and calcium carbonate saturation state (Ω), has a variable impact on the growth and survival of marine invertebrates. Larval stages are thought to be particularly vulnerable to environmental stressors, and negative impacts of ocean acidification have been seen on fertilization as well as on embryonic, larval, and juvenile development and growth of bivalve molluscs. We investigated the effects of high CO2 exposure (resulting in pH = 7.39, Ωar = 0.74) on the larvae of the bay scallop Argopecten irradians from 12 h to 7 d old, including a switch from high CO2 to ambient CO2 conditions (pH = 7.93, Ωar = 2.26) after 3 d, to assess the possibility of persistent effects of early exposure. The survival of larvae in the high CO2 treatment was consistently lower than the survival of larvae in ambient conditions, and was already significantly lower at 1 d. Likewise, the shell length of larvae in the high CO2 treatment was significantly smaller than larvae in the ambient conditions throughout the experiment and by 7 d, was reduced by 11.5%. This study also demonstrates that the size effects of short-term exposure to high CO2 are still detectable after 7 d of larval development; the shells of larvae exposed to high CO2 for the first 3 d of development and subsequently exposed to ambient CO2 were not significantly different in size at 3 and 7 d than the shells of larvae exposed to high CO2 throughout the experiment.
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ArticleOcean and coastal acidification off New England and Nova Scotia(The Oceanography Society, 2015-06) Gledhill, Dwight K. ; White, Meredith M. ; Salisbury, Joseph E. ; Thomas, Helmuth ; Mlsna, Ivy ; Liebman, Matthew ; Mook, Bill ; Grear, Jason S. ; Candelmo, Allison C. ; Chambers, R. Christopher ; Gobler, Christopher J. ; Hunt, Christopher W. ; King, Andrew L. ; Price, Nichole N. ; Signorini, Sergio R. ; Stancioff, Esperanza ; Stymiest, Cassie ; Wahle, Richard A. ; Waller, Jesica D. ; Rebuck, Nathan D. ; Wang, Zhaohui Aleck ; Capson, Todd L. ; Morrison, J. Ruairidh ; Cooley, Sarah R. ; Doney, Scott C.New England coastal and adjacent Nova Scotia shelf waters have a reduced buffering capacity because of significant freshwater input, making the region’s waters potentially more vulnerable to coastal acidification. Nutrient loading and heavy precipitation events further acidify the region’s poorly buffered coastal waters. Despite the apparent vulnerability of these waters, and fisheries’ and mariculture’s significant dependence on calcifying species, the community lacks the ability to confidently predict how the region’s ecosystems will respond to continued ocean and coastal acidification. Here, we discuss ocean and coastal acidification processes specific to New England coastal and Nova Scotia shelf waters and review current understanding of the biological consequences most relevant to the region. We also identify key research and monitoring needs to be addressed and highlight existing capacities that should be leveraged to advance a regional understanding of ocean and coastal acidification.
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ThesisGrowth and development of larval bay scallops (Argopecten irradians) in response to early exposure to high CO2(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2013-02) White, Meredith M.Coastal and estuarine environments experience large variability and rapid shifts in pCO2 levels. Elevated pCO2, or ocean acidification, often negatively affects early life stages of calcifying marine invertebrates, including bivalves, but it is unclear which developmental stage is most sensitive. I hypothesized that initial calcification is a critical stage during which high pCO2 exposure has severe effects on larval growth and development of bay scallop (Argopecten irradians). Using five experiments varying the timing of exposure of embryonic and larval bay scallops to high CO2, this thesis identifies two distinct stages of development during which exposure to high CO2/low pH causes different effects on bay scallop larvae. I show that any exposure to high CO2 consistently reduces survival of bay scallop larvae. I also show that high CO2 exposure during initial calcification (12-24 h post-fertilization) results in significantly smaller shells, relative to ambient conditions, and this size decrease persists through the first week of development. High CO2 exposure at 2-12 h post- fertilization (pre-calcification), does not impact shell size, suggesting that the CO2 impact on size is a consequence of water chemistry during calcification. However, high CO2 exposure prior to shell formation (2-12 h post-fertilization) causes a high incidence of larval shell deformity, regardless of CO2 conditions during initial calcification. This impact does not occur in response to high CO2 exposure after the 2-12 h period. The observations of two critical stages in early development has implications for both field and hatchery populations. If field populations were able to time their spawning to occur during the night, larvae would undergo initial calcification during the daytime, when CO2 conditions are more favorable, resulting in larger veliger larvae. Hatcheries could invest minimal resources to monitor and modify water chemistry only during the first day of development to ensure larva are exposed to favorable conditions during that critical period.
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ArticleElevated pCO2 exposure during fertilization of the bay scallop Argopecten irradians reduces larval survival but not subsequent shell size(Inter-Research, 2014-02-17) White, Meredith M. ; Mullineaux, Lauren S. ; McCorkle, Daniel C. ; Cohen, Anne L.Ocean acidification, characterized by elevated partial pressure of CO2 (pCO2), generally has negative effects on early life stages of invertebrates. We tested the idea that fertilization is a critical CO2 exposure stage for the bay scallop Argopecten irradians by determining the effects on bay scallops of exposure to high CO2 (pCO2 ~2600 ppm, pH ~7.30) from fertilization to 7 d old. To assess the possibility of persistent effects of exposure during fertilization, further treatments included switches from high CO2 to ambient CO2 (pCO2 ~480 ppm, pH ~7.96) and from ambient CO2 to high CO2 at 2 h post-fertilization. Survival of larvae decreased significantly when they were fertilized in high CO2. A switch in CO2 conditions 2 h post-fertilization did not change this effect, suggesting that the critical exposure window for this survival effect is within the first 2 h. In contrast, CO2 conditions during fertilization did not affect larval shell size, but the switch treatments showed that exposure to high CO2 after 2 h post-fertilization decreased shell size, indicating that the exposure window for a size effect was later in development, possibly during shell calcification. Finally, a shell deformity was seen in scallops with continuous exposure to high CO2 and those switched from ambient CO2 to high CO2 at 2 h post-fertilization. Decreased survival during fertilization and smaller larval shell size due to ocean acidification could ultimately reduce the population size of this commercially important bivalve, which has already seen dramatic population decline due to loss of juvenile habitat.