A tale of two spring blooms in a northeast estuary of the USA: how storms impact nutrients, multiple trophic levels and hypoxia

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We explore how anomalously strong winter storms, superposed with managed nitrogen reduction, impacted the 2010 and 2018 spring blooms in the Narragansett Bay (41.62° N, 71.35° W). Anomalously strong winter storms preceding spring of 2010 and 2018 increased annual nutrient inputs above the long-term average annual values for the year, causing a large phytoplankton bloom in spring 2010 and a massive winter-spring bloom in 2018. Flooding from the stronger storm in 2010 caused a smaller increase in primary productivity than the smaller storms prior to spring 2018, probably due to increased flushing rates during the 2010 storm. Neither storm enhanced hypoxia the following summer. During both summers, hypoxia was typical of minimal-hypoxia years, indicating that managed nitrogen reduction which is strongest during summer, remained adequate even in the aftermath of organic inputs from large storms during the colder months. Additionally, some commercially fished species appeared to increase after the storm events. Storm nutrient impacts on commercial species suggest that increasing nitrogen inputs from treatment facilities in colder months might enhance Bay fisheries for squid and hard clam without diminishing summer water quality.

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