Table of Contents

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

Subsets of these data were published in the papers listed in the "Related Resources" section.

Related dataset:
* Pump mesozooplankton samples: https://www.bco-dmo.org/dataset/746107

Methodology:
A CTD and optical plankton counter mounted to a ScanFish platform were towed and undulated behind the vessel.

Sampling and analytical procedures:
The ScanFish was towed at a mean speed of 2.7 m/s with mean vertical descent and ascent rates of 0.3 m/s.

Notes for specific data columns:

Dissolved oxygen concentration (column "oxy"): values corrected vs. CTD rosette casts and Winkler titrations when available.

Sample volume (column "vol"): estimated from OPC mouth opening and changes in lat, lon, and depth

Data column definitions for particle counts and biovolume density include the term "ESD" which stands for "equivalent spherical diameter."

Biovolume densities (data column names beginning with "v_") were calculated using the following formula:
v = sum(4/3*pi*(0.5*ESD*1e-3)^3)/vol

The light attenuance (column "light") has relative units and the OPC unit used starting Sep. 5, 2010 22:30:00 UTC was calibrated differently.

Data processing:
Previously processed CTD files (https://www.bco-dmo.org/dataset/3547) and MIDAS files (https://www.bco-dmo.org/dataset/3548) were synchronized and merged with simultaneously collected OPC data. Quality controlled and interpolated MIDAS data were used as the common reference system for longitude, latitude, and time. Since the OPC clock gradually and unpredictably drifted relative to MIDAS time, synchronization was accomplished by measuring and correcting for temporal lag via cross-correlations of moving windows of OPC and CTD pressure sensor time series (with the remaining error generally <0.5 s). Data were then aggregated into 1 s time bins. The standard reference for depth was OPC pressure, adjusted to compensate for non-zero readings on deck of the research vessel over the course of each cruise. The 15 arc second resolution NOAA NCEI coastal relief model for the northern Gulf of Mexico was used as a reference for bathymetry. Data were divided into distinct vertical profiles, and only those profiles were included in the final dataset that either sampled the water column from <3 m below the surface to <3 above the bottom or sampled >30 m of vertical distance, or both. Estimated OPC particle sizes from 256 to 2048 µm equivalent spherical diameter were aggregated into 12 logarithmically spaced size bins (other particle sizes were excluded). For CTD files with both raw and corrected oxygen data, the corrected version was used. All data processing was performed using the R language and environment for statistical computing.

BCO-DMO Data Manager Processing Notes:
* added a conventional header with dataset name, PI name, version date.
* modified parameter names to conform with BCO-DMO naming conventions. Periods in column names changed to underscores.
* added ISO Timestamp column
* rounded decimal places of columns. Number of decimal places provided by data contributor.
* Missing data values are shown as the BCO-DMO missing data identifier "nd" meaning "no data."

NGOMEX - Living Organisms of the Northern Gulf of Mexico
A synthesis of data collected in the Northern Gulf of Mexico from 2003-2004, 2006-2008 and 2010
Data include:
- CTD Profiles
- Rosette Samples
- MIDAS underway metereological
- Towed SCANFISH
- Net Trawls
- Zooplankton counts

High-resolution mapping of the major ecosystem components of the NGOMEX by year

References:
Kimmel, D. G., W. C. Boicourt, J. J. Pierson, M. R. Roman, X. Zhang. 2010. The vertical distribution and diel variability of mesozooplankton biomass, abundance and size in response to hypoxia in the northern Gulf of Mexico USA. Journal of Plankton Research 32(8): 1185-1202. doi:10.1093/plankt/fbp136

Pierson, J. J., M. R. Roman, D. G. Kimmel, W. C. Boicourt, & X. Zhang. 2009. Quantifying changes in the vertical distribution of mesozooplankton in response to hypoxic bottom waters. Journal of Experimental Marine Biology and Ecology 381: S74-S79. doi.org/10.1016/j.jembe.2009.07.013

Kimmel, D. G., W. C. Boicourt, J. J. Pierson, M. R. Roman, & X. Zhang. 2009. A comparison of the mesozooplankton response to hypoxia in Chesapeake Bay and the northern Gulf of Mexico using the biomass size spectrum. Journal of Experimental Marine Biology and Ecology 381: S65-S73. doi.org/10.1016/j.jembe.2009.07.012

Zhang, H., S. A. Ludsin, D. M. Mason, A. T. Adamack, S. B. Brandt, X. Zhang, D. G. Kimmel, M. R. Roman, & W. C. Boicourt. 2009. Hypoxia-driven changes in the behavior and spatial distribution of pelagic fish and mesozooplankton in the northern Gulf of Mexico. Journal of Experimental Marine Biology and Ecology. 381: S80-91. http://dx.doi.org/10.1016/j.jembe.2009.07.014

GOM - Broader Impacts
The need to understand the impact of this largest oil spill to date on ecosystems and biochemical cycling is self evident. The consequences of the disaster and accompanying clean up measures (e.g. the distribution of dispersants) need to be evaluated to guide further mediating measures and to develop and improve responses to similar disasters in the future. Would it be advantageous if such oil aggregates sink, or should it rather remain suspended? Possibly measures can be developed to enhance sinking or suspension (e.g. addition of ballast minerals) once we understand their current formation and fate. Understanding the particle dynamics following the input of large amounts of oil and dispersants into the water is a prerequisite to develop response strategies for now and in the future.