Experiments were conducted in early and late summer (June and August) 2017 using the in situ equilibration of intact segments of oyster reef (hereafter “reef segments”) with ex situ incubation approach. As part of the larger project, reef segments were incubated first in the dark, then with illumination.
After these incubations were complete, a subset of these samples (4 samples in June and 6 samples in August) was selected for additional study based upon whether the sample had at least one oyster over ~75 mm visible on the surface sediment. For each tray selected, the live oysters and oyster clumps were carefully removed from each tray, placed in clean and empty incubation chambers, aerated for ~1 h, and incubated in the dark. Solutes (NH4+, NO2/3-, SRP) and dissolved gases (O2, N2, Ar, DIC = [H2CO3]+[HCO3-]+[CO32-]) were collected approximately every 45 minutes (4 times total) during each set of incubations from a sampling tube fitted in the lid, while a water replacement tube pulled water from the water bath. Dissolved gases were preserved with 10μl of 50% saturated HgCl2, tightly sealed, submerged in water, and held at or slightly below incubation temperature until analysis. Solute samples were filtered through a 0.45 μm pore-size filter and kept frozen for analysis. N2, O2, and Ar concentrations were measured on a membrane-inlet mass spectrometer within 2 weeks of collection. DIC concentrations were measured using an infrared-based analyzer (Apollo SciTech). Phenol/hypochlorite colorimetry was used to determine NH4+ concentrations. NO2/3-was analyzed spectrophotometrically following Doane and Howarth, while a composite reagent of molybdic acid, ascorbic acid, and trivalent antimony were used to determine SRP concentrations.
Refer to Jackson et al. (2018) for complete methods.