Dataset: Limits of detection and qPCR efficiencies from cruise SAV 17-16 in the South Atlantic Bight aboard the R/V Savannah from 2011 to 2017

Samples were collected from four regions (inshore, midshelf, shelf-break, and oceanic) of the SAB off the Georgia (U.S.A.) coast (Fig. 1; Supporting Information Table S1), with terminology modified from Liu et al. (2018) as follows. “Inshore” stations were within the barrier island complex. “Mid-shelf” stations were outside the barrier island complex to depths < 40 m; due to limited sampling in this zone, no demarcation between “mid-shelf” and “nearshore” stations (as in Liu et al. 2018) was made. “Shelf-break” stations were between 40 m and 500 m depth. While Liu et al. (2018) did not sample waters past the shelf-break, we included deeper stations further offshore (bottom depth > 500 m), which are designated “oceanic” stations. Note that the maximum depth sampled was ≤ 500 m due to equipment limitations. 

Inshore samples were collected from a dock at Marsh Landing on the Duplin River (Sapelo Island) and the dock at the Skidaway Institute of Oceanography (Fig. 1). Both inshore sites are salt marsh-dominated estuaries. Water from both sites was sampled from a depth ≤ 1 m and was processed immediately at a nearby laboratory (the University of Georgia Marine Institute on Sapelo Island or onboard the R/V Savannah). Water quality data for Marsh Landing samples were collected as part of the Sapelo Island National Estuarine Research Reserve monitoring program. Relevant data from the Lower Duplin (“LD”) sonde were downloaded from NOAA/CDMO (http://cdmo. baruch.sc.edu/aqs/, last accessed 22 May 2018). 

Most SAB samples were collected in August 2017 on the R/V Savannah (cruise SAV-17-16) along transects across the continental shelf and the Gulf Stream and into the western Sargasso Sea, with sampling focused around the shelf-break (Fig. 1). Water from multiple depths was collected using 12-liter Niskin bottles mounted on a rosette equipped with a Sea-Bird SBE25 CTD. Profiles of salinity, temperature, dissolved oxygen, fluorescence, and photosynthetically active radiation (PAR) were collected using the CTD system as described previously (Liu et al. 2018). PAR attenuation (Kd) was calculated from plots of ln(PAR) vs. depth as in Liu et al. (2018).  Two additional SAB stations were sampled in October 2011 (described previously by Liu et al. 2015 and Tolar et al. 2017) and are referred to as “2011-4” and “2011-12” (Fig. 1). Environmental data and some of the microbial and rate data from 2011 stations are available in other publications (Liu et al. 2015; Tolar et al. 2017; see BCO-DMO dataset DON_Oxidation https://www.bco-dmo.org/dataset/767048).