Nitrogen uptake measurements during a summer 2022 Alexandrium catenella bloom in the Alaskan Arctic (NRS2022_02S)

In the rapidly changing Arctic ecosystem, the recent emergence of harmful algal blooms (HABs) threatens human and ecosystem health. There is increasing evidence that toxic dinoflagellates of the Alexandrium genus are blooming in the Pacific Arctic Ocean, in dense enough concentrations to necessitate shellfishing closures and to detect toxins in marine mammals that forge in Alaskan waters. Our understanding of the nutrient dynamics that sustain HABs in the Pacific Arctic is severely limited, particularly as these blooms tend to occur in late summer when dissolved inorganic nitrogen is drawn down and limits phytoplankton growth. Dissolved organic nitrogen could prove a critical nitrogen source for HABs in the Pacific Arctic, as it has in other regions. This dataset presents measurements taken on Leg 2 of a research cruise (NRS2022_02S) on the Research Vessel (R/V) Norseman II in Aug-Sep 2022 to characterize the nutrient usage by A. catenella. It includes the nutrients (silicate, phosophate, total dissolved nitrogen, and four dissolved nitrogen substrates), particulate organic carbon and nitrogen, and chlorophyll concentrations; phytoplankton community composition; uptake rates; and nitrogen relative preference indices associated with13 incubation experiments in which we used stable isotope tracers to measure nitrogen uptake by the surface biological community. Tracer were 15N-nitrate, 15N-ammonium, 13C15N-urea, and 13C15N-dissolved free amino acids. We also include the salinity and temperature measurements from CTD-mounted sensors for water collection from Niskin bottles for each incubation set up. Other associated datasets include: Leah McRaven & Robert Pickart. (2024). Conductivity Temperature Depth (CTD) data from the Norseman II (NRS22-1s and NRS22-2s), as part of the 2022 Origin and Fate of Harmful Algal Blooms in the Warming Chukchi Sea cruise. Arctic Data Center. doi:10.18739/A2B853K56. Evangeline Fachon, Donald M Anderson, Mrunmayee Pathare, Michael Brosnahan, Eric Muhlbach, Kali Horn, Nathaniel Spada, & Anushka Rajagopalan. (2024). Alexandrium catenella planktonic cell abundance and toxicity from the Norseman II (NRS2022_01S and NRS2022_02S), as part of the 2022 Origin and Fate of Harmful Algal Blooms in the Warming Chukchi Sea cruise. Arctic Data Center. doi:10.18739/A2804XM7S. Miguel Goni & Dean Stockwell. (2024). Conductivity-Temperature-Depth (CTD) Bottle Data from the Norseman II cruises (NRS2022_01S and NRS2022_02S) including Particulate Organic Carbon (POC) Particulate Nitrogen (PN), Chlorophyll (Chl), Phaeophytin (Phaeo), and dissolved nutrients (Nitrate, Nitrite, Phosphate, Silicate, and Ammonium) (2022). Arctic Data Center. doi:10.18739/A2M90249T.