Abstract:

Deep pelagic habitat from the entire Gulf of Mexico (GOM) was classified using the deviation of sea surface height (SSH) from mean SSH for the entire GOM and water temperature at 300 m water depth, founded on ocean condition data from the 1/25° GOM HYbrid Coordinate Ocean Model (HYCOM). Pelagic habitats were segregated into anticyclonic, mixed boundaries, and common water units – all of which likely produce varying levels of forage for deep-sea fauna and may be trophic drivers. Model classifications were compared to classifications based on water column temperature and salinity at depth, as measured by CTD casts during cruises DP01-DP04 in the northern GOM (GRIIDC datasets R4.x257.230:0004, R4.x257.230:0010, R4.x257.230:0011, and R4.x257.230:0012). The classification scheme was further cross-validated by comparing the model classifications to classifications based on microbial communities found within the same water masses. This tool will be used to aid pelagic community analyses of fauna collected by DEEPEND cruises in the GOM spanning 2015-2016.

Suggested Citation:

Matthew W. Johnston, Rosanna J. Milligan, Cole G. Easson, Sergio deRada, Bradley Penta, Tracey T. Sutton. 2018. Habitat classification of the Gulf of Mexico (GOM) using the HYbrid Coordinate Ocean Model (HYCOM) and salinity/temperature profiles, cruises DP01-DP04, May 2015 to August 2016. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7QR4VK0

Publications:

Johnston, M. W., Milligan, R. J., Easson, C. G., deRada, S., English, D. C., Penta, B., & Sutton, T. T. (2019). An empirically validated method for characterizing pelagic habitats in the Gulf of Mexico using ocean model data. Limnology and Oceanography: Methods. doi:10.1002/lom3.10319

Boswell, K. M., D’Elia, M., Johnston, M. W., Mohan, J. A., Warren, J. D., Wells, R. J. D., & Sutton, T. T. (2020). Oceanographic Structure and Light Levels Drive Patterns of Sound Scattering Layers in a Low-Latitude Oceanic System. Frontiers in Marine Science, 7. doi:10.3389/fmars.2020.00051

Purpose:

To classify GOM pelagic waters and aid pelagic community analyses of fauna collected by DEEPEND cruises in the GOM spanning the years 2015-2016.

Data Parameters and Units:

classifications_2015.csv - 2015 classifications classifications_2016.csv - 2016 classifications columns (units):description for both files: day (days):julian day of year, lat (decimal degrees):latitude, lon (decimal degrees):longitude, mean_ssh (m):GOM mean sea surface height anomaly for the day, ssh_anom (m):location sea surface height anomaly, temp_300 (°C):location temperature at 300m water depth, depth (m):water depth, ssh_class:habitat classification type (AR - anticyclonic, MIX - mixture, CW - common water, UK - unknown)

Methods:

Anticyclonic rings (AR) are identified by an elevated mean sea surface height anomaly (SSHa), increased temperatures at depth, low concentrations of chlorophyll a, and the presence of the Subtropical Underwater water mass. ssh_anom > mean_ssh + 0.067 & Temp_300 > 15.92 °C Gulf Common Water (CW) is resident GoM water that is cooler than AR, has depressed SSHa, higher concentrations of chlorophyll a, and an absence of the Subtropical Underwater water mass. ssh_anom ≤ mean_ssh & Temp_300 < 13.46 °C Mixed water (MIX) is water that is a gradient between AR and CW water types. ssh_anom > mean_ssh & ssh_anom < mean_ssh + 0.067 & Temp_300 = 13.46 °C to 15.92 °C Unknown water is water that was unable to be classified by our scheme based on the above model values.

Individual Files: