2011 GRI Sampling cruise: macroalgae and macrocrustaceans offshore the Northern Gulf of Mexico

This video highlights sampling of seaweeds and macrocrustaceans in the northern Gulf of Mexico by means of a box dredge. The August 26-30, 2011, collecting cruise was funded by a Gulf of Mexico Research Initiative RFP-III Summer/Fall 2011Sampling Award (GRI-008, http://www.gulfresearchinitiative.org/research/awards/rfp-iii-awards/) granted to Suzanne Fredericq and Darryl Felder from the University of Louisiana at Lafayette (‪http://biology.ucs.louisiana.edu/). The award is entitled "Stop-gap Sampling to Assess the Impact of the Deepwater Horizon Oil Spill on the Macroalgae and Macrocrustaceans in the Northern Gulf of Mexico".

The collections are facilitating critical assessment of pre- and post-oil spill impacts on the diversity, vitality, and distribution of these offshore organisms living principally at 53-90 m depth. The 5-day ship-based sampling expedition centered on previously studied hard banks throughout the Gulf. Results analyzed from the dredging expedition off Louisiana, Mississippi and Alabama (August 26-30, 2011) indicate that algal diversity in all dredged sites was either extremely low or non-existent. Decapod crustacean populations (and associated fauna, such as sponges and molluscs) were likewise depressed, and diversity of the previously documented assemblage appeared limited.

Darryl Felder narrates the cruise course at the beginning of the video. Collecting started at Sackett Bank, SW of the delta near the edge of the Mississippi Canyon. As was the situation in December 2010, strong petroleum odors were pervasive when the dredge was retrieved from ~55 m depth at one site, Ewing Bank 2 (Fish Haven) far west of the Deepwater Horizon Explosion. The video documents some of the diversity of substrata. e.g. rhodoliths, carbonate nodules, mud, rubble, shells or shell hash.

The Hourglass-design box dredge provides a now standardized method of semi-quantitative sampling. It is an effective tool only on substrata of low relief that consist of loose rocks and rubble, shells or shell hash, and calcareous nodules (rhodoliths), the typical substrata of Gulf deep banks.

Macrocrustaceans and associated fauna dredged with a benthic skimmer from depths of ~100-1750 m can be viewed at http://www.youtube.com/watch?v=qa7RMptjiTI

The expedition departed from LUMCON in Cocodrie LA, on board the R/V Pelican, a 32 m (105ft) ABS Class "A-1+ Oceanographic, steel-hull coastal research vessel operated by UNOLS.



Filmed and edited by S. Fredericq.

Category:

Science & Technology

Tags:

• saweeds
• bp
• oil
• deepwater horizon
• biodiversity
• taxonomy
• systematics
• biogeography
• marine Gulf Of Mexico Cruise
• exploration