Dataset: Louisiana shelf water column production and respiration measured by change in oxygen in light and dark bottle incubations during four cruises in 2017

Samples for plankton community respiration (WR) measurements were collected from several depths in the water column including the surface layer, the bottom layer, the layer at depth of chlorophyll maximum, midwater oxygen maximum, and midwater oxygen minimum. For each sample collected, three transparent (light) glass bottles and three dark glass bottles were filled directly from the ship's Niskin bottle array (Murrell and Lehrter, 2011). Aliquots were put into acid-cleaned 300 milliliter BOD (biochemical oxygen demand) bottles for light-dark incubation experiments. After initial O₂ measurements were taken (T0), samples were placed in a darkened incubator that maintained surface water temperatures using water supplied continuously from the ship’s hull pump. Light bottle treatments were incubated in an outdoor incubator with screening that reduced ambient light by 50%. Dark bottle treatments were also placed in the outdoor incubator but were kept dark by their black liners and caps. 

For more detailed methods see Murrell et al. (2013) and Murrell and Lehrter (2011).

Concentrations of O₂ were measured initially and after 24 hours using a Hach or YSI oxygen sensor and temperature probe. Salinity values for each sample were obtained from the ship's CTD (SeaBird 911). Net primary production rates were calculated as the change in O₂ over time in light bottles screened at 50% of ambient sunlight and incubated for 24 hours, expressed in units of millimoles oxygen per cubic meter per day (mmol O₂ m^-3 d^-1). Respiration rates were calculated as the change in O₂ over time in dark bottles incubated for 24 hours, expressed in units of millimoles oxygen per cubic meter per day (mmol O₂ m^-3 d^-1).

Problem report: Some of the incubation bottles had their caps come off during incubations. These values are labeled as NAN (not a number) in the dataset.

Note: Dissolved oxygen data were recorded in mg/L for the April 2017 cruise and in percent saturation for the July and September cruises.