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1. Historical biogeographic range shifts and the influence of climate change on ocean quahogs ( Arctica islandica ) on the Mid-Atlantic Bight

   https://doi.org/10.1177/09596836221101275  

   LeClaire, Alyssa M; Powell, Eric N; Mann, Roger; Hemeon, Kathleen M; Pace, Sara M; Sower, Jill R; Redmond, Theresa E (September 2022, The Holocene)

   The Holocene, starting approximately 11.7 cal ka, is characterized by distinct periods of warming and cooling. Despite these known climate events, few temperature proxy data exist in the northwestern Atlantic Ocean. One potential record of past water temperatures is preserved in the marine fossil record. Shell growth of ocean quahogs ( Arctica islandica), a long-lived bivalve, can provide records of past environmental conditions. Arctica islandica habitat includes the Mid-Atlantic Bight (MAB), an area rapidly warming as a consequence of climate change. The Cold Pool, a bottom-trapped water mass on the outer continental shelf within the MAB, rarely rises above 15°C. Ocean quahogs inhabiting the MAB are confined to the Cold Pool as a consequence of an upper thermal limit for the species of ~15–16°C. Recently, dead A. islandica shells were discovered outside of the species’ present-day range, suggesting that the Cold Pool once extended further inshore than now observed. Shells collected off the Delmarva Peninsula were radiocarbon-dated to identify the timing of habitation and biogeographic range shifts. Dead shell ages range from 4400 to 60 cal BP, including ages representing four major Holocene cold events. Nearly absent from this record are shells from the intermittent warm periods. Radiocarbon ages indicate that ocean quahogs, contemporaneous with the present MAB populations, were living inshore of their present-day distribution during the past 200 years. This overlap suggests the initiation of a recent biogeographic range shift that occurred as a result of a regression of the Cold Pool following the Little Ice Age. 

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2. Historical biogeographic range shifts and the influence of climate change on ocean quahogs

   LeClaire, A.M. (January 2022, Holocene)

   The Holocene, starting approximately 11.7 cal ka, is characterized by distinct periods of warming and cooling. Despite these known climate events, few temperature proxy data exist in the northwestern Atlantic Ocean. One potential record of past water temperatures is preserved in the marine fossil record. Shell growth of ocean quahogs (Arctica islandica), a long-lived bivalve, can provide records of past environmental conditions. Arctica islandica habitat includes the Mid-Atlantic Bight (MAB), an area rapidly warming as a consequence of climate change. The Cold Pool, a bottom-trapped water mass on the outer continental shelf within the MAB, rarely rises above 15°C. Ocean quahogs inhabiting the MAB are confined to the Cold Pool as a consequence of an upper thermal limit for the species of ~15–16°C. Recently, dead A. islandica shells were discovered outside of the species’ present-day range, suggesting that the Cold Pool once extended further inshore than now observed. Shells collected off the Delmarva Peninsula were radiocarbon-dated to identify the timing of habitation and biogeographic range shifts. Dead shell ages range from 4400 to 60 cal BP, including ages representing four major Holocene cold events. Nearly absent from this record are shells from the intermittent warm periods. Radiocarbon ages indicate that ocean quahogs, contemporaneous with the present MAB populations, were living inshore of their present-day distribution during the past 200 years. This overlap suggests the initiation of a recent biogeographic range shift that occurred as a result of a regression of the Cold Pool following the Little Ice Age. 

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3. Interactive Effects of Climate Change‐Induced Range Shifts and Wind Energy Development on Future Economic Conditions of the Atlantic Surfclam Fishery

   https://doi.org/10.1002/mcf2.10232  

   Stromp, Stephanie; Scheld, Andrew M.; Klinck, John M.; Munroe, Daphne M.; Powell, Eric N.; Mann, Roger; Borsetti, Sarah; Hofmann, Eileen E. (April 2023, Marine and Coastal Fisheries)

   Abstract Rising water temperatures along the northeastern U.S. continental shelf have resulted in an offshore range shift of the Atlantic surfclamSpisula solidissimato waters still occupied by ocean quahogsArctica islandica. Fishers presently are prohibited from landing both Atlantic surfclams and ocean quahogs in the same catch, thus limiting fishing to locations where the target species can be sorted on deck. Wind energy development on and around the fishing grounds will further restrict the fishery. A spatially explicit model of the Atlantic surfclam fishery (Spatially Explicit Fishery Economics Simulator) has the ability to simulate the consequences of fishery displacement due to wind energy development in combination with fishery and stock dynamics related to the species' overlap with ocean quahogs. Five sets of simulations were run to determine the effect of varying degrees of species overlap due to Atlantic surfclam range shifts in conjunction with fishing constraints due to wind farm development. Simulations tracked changes in relative stock status, fishery performance, and the economic consequences for the fishery. Compared to a business‐as‐usual scenario, all scenarios with less‐restrictive fishing penalties due to species overlap exhibited higher raw catch numbers but also greater reductions in revenue and increases in cost after the implementation of wind farms. This analysis serves to demonstrate the response of the Atlantic surfclam fishery to combined pressures from competing ocean uses and climate change and emphasizes the potential for economic disruption of fisheries as climate change interacts with the evolution of ocean management on the continental shelf. 

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4. Oceanographic Variability in the Rapidly Warming Coastal Mid-Atlantic (USA) over the last 200 years: Insights from Shell-Based Geochemistry and Growth Histories

   Sun, H.; Wanamaker, A.; Thatcher, D.; Whitney, N.; Jarosinski, L.; Stewart, J.; Williams, B.; LaVigne, M. (December 2022, American Geophysical Union Fall Meeting)

   Warming in recent decades in the North Atlantic Ocean has been heterogeneous, with locations along the northwestern Atlantic experiencing some of the largest and fastest warming in the last 100 years. This region is important for fisheries but has limited spatial and temporal hydrographic instrumental series extending beyond the past decades, especially along the coastal United States portion of the northwestern Atlantic, thus impacting our understanding of past climatic variability. To provide a longer temporal context for these changes, we constructed a continuous master shell growth chronology spanning the last two centuries and provided geochemical records from the Mid-Atlantic region using the long-lived marine bivalve Arctica islandica. Shells were collected on the outer shelf region off Ocean City, Maryland, in ~ 60 m water depth. This region is sensitive to large-scale North Atlantic Ocean dynamics, including the Atlantic Meridional Overturning Circulation (AMOC) and Gulf Stream eddies. Based on growth histories and shell oxygen isotopes, we provide evidence of hydrographic variability beyond the relatively short instrumental period and evaluate the likely causes for these changes. These data allow us to better characterize recent and past oceanographic changes in the Mid-Atlantic region, synthesize the new results with previously developed paleo-records in the northwestern Atlantic, and provide guidance for the management of fisheries in this region. 

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5. Evidence of coherent warming in the northwest Atlantic Ocean from Arctica islandica oxygen isotope records

   Thatcher, D.; Whitney, N.; Walton, A.; Sun, H.; Jarosinski, L.; Wanamaker, A.; LaVigne, M.; Williams, B.; Stewart, J. (May 2023, International Sclerochronology Conference)

   Parts of the northwest Atlantic Ocean, including the Gulf of Maine, along the northeastern coast of the United States, are warming at a rate as much as four times faster than the global ocean, according to instrumental and satellite records. In addition to the longer-term temperature increases, the frequency and severity of marine heat waves have been increasing. Combined, the ecological impacts are numerous and concerning, yet our understanding of past climate in this region is incomplete due to sparse and short-duration instrumental records. Here we present annually resolved oxygen isotope records from the marine bivalve, Arctica islandica, from five locations ranging from Jonesport and Seguin Island in the Gulf of Maine to Long Island, New York, Cape May, New Jersey, and Ocean City, Maryland in the Mid-Atlantic Bight, a span of over 870 km along the Atlantic coast. Several of the isotope records span the last 100 years or more and all records show coherent, substantial warming since at least 1980 CE. The level of warming indicated in the shell oxygen isotopes is comparable to the 0.5 °C per decade (1980-2020 CE) warming also shown in the instrumental record of sea surface temperature from Boothbay Harbor along the central coast in the Gulf of Maine. These five spatially distant isotope records span different oceanographic conditions and dynamics, including water mass sources, yet they all indicate a substantial warming in recent decades, likely related to increased anthropogenic warming. Beyond reconstructing seawater temperature prior to instrumental records, a major goal of this work is to disentangle the global warming signal from these records to better understand the underlying ocean dynamics also influencing these records. 

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