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1. Spatially varying phytoplankton seasonality on the Northwest Atlantic Shelf: a model-based assessment of patterns, drivers, and implications

   https://doi.org/10.1093/icesjms/fsab102  

   Zang, Zhengchen; Ji, Rubao; Feng, Zhixuan; Chen, Changsheng; Li, Siqi; Davis, Cabell S (June 2021, ICES Journal of Marine Science)

   Oliver, Matt (Ed.)

   Abstract The signal of phytoplankton responses to climate-related forcing can be obscured by the heterogeneity of shelf seascapes, making them difficult to detect from fragmented observations. In this study, a physical–biological model was applied to the Northwest Atlantic Shelf to capture the seasonality of phytoplankton. The difference in phytoplankton seasonality between the Mid-Atlantic Bight (MAB) and the Gulf of Maine (GoM) is a result of the interplay between nutrients and temperature: In the MAB, relatively high temperature in the cold season and longer oligotrophic environment in the warm season contribute to an earlier winter bloom and a later fall bloom; in the GoM, low temperature and strong mixing limit phytoplankton growth from late fall to early spring, resulting in a later spring bloom and an earlier fall bloom. Although the temperature difference between the GoM and the MAB might decrease in the future, stratification and surface nutrient regimes in these two regions will remain different owing to distinct thermohaline structures and deep-water intrusion. The spatial heterogeneity of phytoplankton dynamics affects pelagic and benthic production through connections with zooplankton and benthic–pelagic coupling. 

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2. Atlantic sea scallop energy budget data on the Northeast U.S. Shelf, monthly in 2010 and 2012

   https://doi.org/10.6073/PASTA/665DDFC326826DF5740ECA24194529FE  

   Zang, Zhengchen (January 2022, Environmental Data Initiative)

   This dataset includes monthly Atlantic sea scallop energy budget data from Georges Bank to the Mid-Atlantic Bight based on Scope For Growth (SFG) model results in 2010 and 2012. Results were supported in part by Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER). For more details please see: Zang, Z., et al. (2022) Modeling Atlantic sea scallop (Placopecten magellanicus) scope for growth on the Northeast U.S. Shelf. Fisheries Oceanography, https://doi.org/10.1111/fog.12577. 

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3. What Drives the Mean Along‐Shelf Flow in the Northwest Atlantic Coastal Ocean?

   https://doi.org/10.1029/2024JC021079  

   Chen, Ke; Yang, Jiayan (July 2024, Journal of Geophysical Research: Oceans)

   Abstract A long‐standing hypothesis is that the steady along‐shelf circulation in the Northwest Atlantic (NWA) coastal ocean is driven by buoyancy input from continental freshwater runoff. However, the forcing from the freshwater runoff has not been adequately evaluated and compared with other potential driving mechanisms. This study investigates the roles of both wind stress and freshwater runoff in driving the mean along‐shelf flow in the NWA coastal ocean and examines other potential drivers using a newly developed high‐resolution regional model with realistic forcing conditions. The results reveal that wind stress has a larger impact than freshwater runoff on the overall mean circulation and along‐shelf sea‐level gradient on the NWA shelf. While the continental freshwater input consistently contributes to the equatorward along‐shelf flow and higher sea level along the coast, wind stress is more effective for the setup of the broad‐scale circulation pattern by driving the along‐shelf flow on the Labrador Shelf and opposing the flow in the Mid‐Atlantic Bight and on the Scotian Shelf. In addition to the local wind and continental runoff, the sub‐Arctic inflow from higher latitude is an essential part of the NWA shelf circulation system. This remote driver directly contributes to the along‐shelf flow and insulates the shelf flow from the Gulf Stream on the southern shelves. 

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4. Unusual Hemiaulus bloom influences ocean productivity in Northeastern US Shelf waters

   https://doi.org/10.5194/bg-21-1235-2024  

   Castillo_Cieza, S_Alejandra; Stanley, Rachel_HR; Marrec, Pierre; Fontaine, Diana_N; Crockford, E_Taylor; McGillicuddy_Jr, Dennis_J; Mehta, Arshia; Menden_Deuer, Susanne; Peacock, Emily_E; Rynearson, Tatiana_A; et al (March 2024, Biogeosciences)

   Abstract. Because of its temperate location, high dynamic range of environmental conditions, and extensive human activity, the long-term ecological research site in the coastal Northeastern US Shelf (NES) of the northwestern Atlantic Ocean offers an ideal opportunity to understand how productivity shifts in response to changes in planktonic community composition. Ocean production and trophic transfer rates, including net community production (NCP), net primary production (NPP), gross oxygen production (GOP), and microzooplankton grazing rates, are key metrics for understanding marine ecosystem dynamics and associated impacts on biogeochemical cycles. Although small phytoplankton usually dominate phytoplankton community composition and Chl a concentration in the NES waters during the summer, in August 2019, a bloom of the large diatom genus Hemiaulus, with N2-fixing symbionts, was observed in the mid-shelf region. NCP was 2.5 to 9 times higher when Hemiaulus dominated phytoplankton carbon compared to NCP throughout the same geographic area during the summers of 2020–2022. The Hemiaulus bloom in summer 2019 also coincided with higher trophic transfer efficiency from phytoplankton to microzooplankton and higher GOP and NPP than in the summers 2020–2022. This study suggests that the dominance of an atypical phytoplankton community that alters the typical size distribution of primary producers can significantly influence productivity and trophic transfer, highlighting the dynamic nature of the coastal ocean. Notably, summer 2018 NCP levels were also high, although the size distribution of Chl a was typical and an atypical phytoplankton community was not observed. A better understanding of the dynamics of the NES in terms of biological productivity is of primary importance, especially in the context of changing environmental conditions due to climate processes. 

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5. Understanding physical drivers of the 2015/16 marine heatwaves in the Northwest Atlantic

   https://doi.org/10.1038/s41598-021-97012-0  

   Perez, E.; Ryan, S.; Andres, M.; Gawarkiewicz, G.; Ummenhofer, C. C.; Bane, J.; Haines, S. (September 2021, Scientific Reports)

   Abstract The Northwest Atlantic, which has exhibited evidence of accelerated warming compared to the global ocean, also experienced several notable marine heatwaves (MHWs) over the last decade. We analyze spatiotemporal patterns of surface and subsurface temperature structure across the Northwest Atlantic continental shelf and slope to assess the influences of atmospheric and oceanic processes on ocean temperatures. Here we focus on MHWs from 2015/16 and examine their physical drivers using observational and reanalysis products. We find that a combination of jet stream latitudinal position and ocean advection, mainly due to warm core rings shed by the Gulf Stream, plays a role in MHW development. While both atmospheric and oceanic drivers can lead to MHWs they have different temperature signatures with each affecting the vertical structure differently and horizontal spatial patterns of a MHW. Northwest Atlantic MHWs have significant socio-economic impacts and affect commercially important species such as squid and lobster. 

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