Dataset: Pelagic primary production and respiration in the York River Estuary, 2018-2021

Data were collected on several single-day cruises on small privateers out of the Virginia Institute of Marine Science, Gloucester Point, VA. Dissolved oxygen concentrations were measured with a Hach HQ40d portable oxygen meter and LDO101 luminescent dissolved oxygen sensors.  Sensors were calibrated in water-saturated air prior to each incubation, and re-checked post-incubation.  Salinity and turbidity were measured with a YSI 6600V2 connected to a ship-board Dataflow system and calibrated using YSI calibration solutions.  Chlorophyll-a concentrations were measured on a 10 AU Turner Designs fluorometer periodically calibrated to a stock solution of known concentration and checked before each run with a solid standard from Turner Designs.

During 2018-19, surface water was collected bimonthly from five fixed channel stations along the axis of the YRE. During 2020 and 2021, surface water was collected approximately weekly at stations inside and outside of bloom patches (n=3 each) in late summer in the lower YRE; station locations followed individual bloom patches which varied cruise to cruise. Water was held in blackened bottles at in situ temperatures until being returned to the lab. 

Metabolic incubations followed the methods of Giordano et al. (2012, Mar Ecol Prog Ser 458: 21–38) and Lake et al. (2013, Mar Ecol Prog Ser 492:21–39). Unfiltered water was placed into 60 ml light and dark biological oxygen demand (BOD) bottles and incubated in the dark (n=4 bottles per station) and light (10 irradiance values, 1 bottle each per station) at in situ temperatures in a light gradient box with illumination provided by a metal halide lamp. Irradiance levels varied from approximately 30 to over 2,000 uE/m2/s photosynthetically active radiation. Light bottles were typically incubated for 1-3 hours while dark bottles were incubated overnight to obtain a measurable change in oxygen. Salinity and turbidity of the water samples were obtained from the associated Dataflow record on each cruise (measured with a YSI 6600V2 datasonde). Triplicate samples for chlorophyll-a determination at each station were filtered through 0.7 um glass fiber filters which were frozen prior to analysis following Arar and Collins (1997, EPA Method 445.0). Samples were extracted in the dark for 24 h in 8 ml of a 45:45:10 dimethyl sulfoxide : acetone: distilled water solution with 1% diethylamine (Shoaf and Lium 1976, Limnol Oceanogr 21: 926−928), and read on a 10 AU Turner Designs fluorometer before and after acidification to compute active chlorophyll-a.