Phytoplankton and Bacterial Assemblage Responses to Nitrogen Inputs in River- Dominated Estuaries Surrounding New York City

New York City (NYC) is surrounded by ‘urban estuaries’ that receive excessive nitrogen (N) inputs from wastewater associated with combined sewer overflow (CSO) systems, non-point source runoff, atmospheric deposition, and other sources. This elevated N-load contributes to numerous water quality impairments, such as harmful algal blooms (HABs) and seasonal hypoxia from microbial respiration of dissolved organic carbon (DOC). In partnership with NY and CT state long-term water quality and hypoxia monitoring efforts and regional collaborators, we have been conducting multi-year surveys of Long Island Sound (LIS) physical water quality, ecological (bacteria, phytoplankton), and biogeochemical (nutrients, chlorophyll) features, emphasizing the Western LIS channel and shoreline. We have identified distinct spatial patterns of how variations in N-form (inorganic vs. organic) and source (particularly their proximity to CSOs) drive dominant phytoplankton taxa, including HAB- forming dinoflagellates, their linkages with bacterial population numbers, and transitions in N- form pre- during, and post-hypoxia. Recently, we have extended these observations to additional NYC rivers, including the Hudson River and adjacent watersheds. Here we compare and contrast how dissolved organic N vs. inorganic N (nitrate vs. ammonium) loadings combined with DOC availability governs the relative prevalence of dinoflagellates to diatoms in Western LIS and surrounding NYC waterways and their associations with bacterial assemblages. Results are broadly relevant to N-management across other temperature, urban estuaries.

Primary Presenter: Dianne Greenfield, City University of New York (secretary@aslo.org)

Authors:

Dianne Greenfield, Advanced Science Research Center at the Graduate Center, City University of New York  (secretary@aslo.org)

Mariapaola Ambrosone, Advanced Science Research Center at the Graduate Center, City University of New York  (mambrosone@gc.cuny.edu)

Nicolle Navaretta, School of Earth and Environmental Sciences, Queens College  (nicolle.navaretta04@qmail.cuny.edu)

Sequoia Kessler, School of Earth and Environmental Sciences, Queens College  (sequoia.kessler80@qmail.cuny.edu)

Nicholas Russell, School of Earth and Environmental Sciences, Queens College  (NICHOLAS.RUSSELL08@qmail.cuny.edu)

Moonmoon Ahmed, School of Earth and Environmental Sciences, Queens College  (moonmoon.ahmed27@qmail.cuny.edu)

Georgie Humphries, Advanced Science Research Center at the Graduate Center, City University of New York  (ghumphries@gc.cuny.edu)