Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

All methods are described in Kapsenberg et al. (2015). Data were collected using an autonomous SeaFET pH sensor containing Honeywell DuraFET electrodes (Martz et al., 2010). Sensor depth was 18 m with ~27 m bottom depth. Sensors sampled on a 4-hour frequency.

Conversion from voltage to pH (on a total scale) was performed using a single discrete calibration sample  collected via SCUBA using a 5 L GO-FLO sampling bottle. Sample collection was conducted within the first two weeks of sensor deployment, after sensor conditioning to seawater, in-situ. Samples were preserved with saturated mercuric chloride Standard Operating Procedure (SOP) 1 (Dickson et al., 2007) and analyzed for spectrophotometric pH (total scale, at 25 degrees Celsius) and total alkalinity following SOP 6b and 3b (Dickson et al. 2007). Sample salinity was measured using a calibrated YSI 3100 Conductivity Instrument. In-situ pH was calculated using the program CO2Calc [Version 1.0.1, 2010, U.S. Geological Survey] using SeaFET temperature recorded at the time of sample collection.

SeaFET thermistors were not individually calibrated resulting in a maximum estimated temperature offset of ~0.3 degrees Celsius.

All processing was conducted in R (v.3.5.1) using seacarb (v.3.2.8) to generate calibration coefficients for the sensor that were later applied to the datset. 

BCO-DMO Processing Notes:

- appended lat, lon, sensor_depth, and water_depth columns to include spatial information with the data.
- removed first column as it was an index for the row number.

Abstract: The research supported in this project will examine the effects of environmental change on a key Antarctic marine invertebrate, a pelagic mollusk, the pteropod, Limacina helicina antarctica. There are two main activities in this project: (1) to deploy oceanographic equipment, in this case, autonomously recording pH sensors called SeaFETs and other devices that record temperature and salinity, and (2) to use these environmental data in the laboratory at McMurdo Station to study the response of the marine invertebrates to future changes in water quality that is expected in the next few decades. Notably, changes in oceanic pH (aka ocean acidification) and ocean warming are projected to be particularly threatening to calcifying marine organisms in cold-water, high latitude seas, making tolerance data on these organisms a critical research need in Antarctic marine ecosystems. 

These Antarctic shelled-animals are especially vulnerable to dissolution stress from ocean acidification because they currently inhabit seawater that is barely at the saturation level to support biogenic calcification. Indeed, these polar animals are considered to be the 'first responders' to chemical changes in the surface oceans. Thus, this project will lead to information about the adaptive capacity of L. helcina antarctica. From an ecological perspective this is important because this animal is a critical part of the Antarctic food chain in coastal waters and changes in its abundance will impact other species. Finally, the research conducted in this project will serve as a training and educational opportunity for undergraduate and graduate students as well as postdoctoral scholars.