Many estuaries that fringe the Gulf of Maine are highly productive areas for shellfish aquaculture while also subject to low aragonite saturation state (Ω Ar) from both Gulf of Maine waters and freshwater. Due to the influence of these outside physical conditions and biological processes that occur within the estuary, Ω Ar can be highly variable. To better understand how Ω Ar changes from daily to seasonal time scales within estuaries, we described high frequency changes in aragonite saturation state in the largest oyster growing region in northern New England, the Damariscotta River estuary, Maine, during the shellfish growing season in 2018 using hourly buoy data and discrete samples. Ω Ar ranged from 1 to 2.5 between late May and early October with daily ranges frequently exceeding 0.5. Ω Ar was predominantly controlled by temperature and salinity at the seasonal scale, but driven more by net ecosystem metabolism on daily - bi-weekly time scales. The most prominent feature of this system was the importance of spring-neap tidal cycles, with spring tides increasing turbidity, nitrate, and respiration, and then subsequently primary production. In late summer, peak high oyster filtration led to anomalously low turbidity, chlorophyll, and total alkalinity; however the system was net autotrophic during this period and Ω Ar increased by 0.6 on average during this time. Here, we attempt to disentangle the strong interconnection between estuary morphology, tides, net ecosystem metabolism, and Ω Ar in an important oyster growing area.

Primary Presenter: Kate Liberti, University of Maine (kate.liberti@maine.edu)

Authors:

Kate Liberti, University of Maine  (kate.liberti@maine.edu)

Damian Brady, University of Maine  (damian.brady@maine.edu)

Jeremy Testa, University of Maryland  (jtesta@umces.edu)

Chris Hunt, University of New Hampshire  (chunt@unh.edu)

Lawrence Mayer, University of Maine  (Lmayer@maine.edu)