2010 NSF RAPID cruise: macroalgae and macrocrustaceans offshore the NW Gulf of Mexico

The NSF RAPID grant (DEB-1045690) awarded to Suzanne Fredericq and Darryl Felder from the University of Louisiana at Lafayette (‪http://biology.ucs.louisiana.edu/) and entitled "RAPID: Impacts of the Deepwater Horizon crude oil spill on the diversity of macroalgae and macrocrustaceans inhabiting deepwater hard banks in the NW, NE and SE Gulf of Mexico" is 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 (December 2-6, 2010) indicate that algal diversity (mostly members of the red algal family Peyssonneliaceae and Corallinaceae; Verdigellas in the green algal family Palmophyllaceae; and the crustose form of Lobophora in the brown algal family Dictyotaceae) 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.

The molluscs filmed here were preserved and identified by Emilio Garcia: Conus ermineus, Conus cancellatus, Euvola "papyracea", Turritella exozeta, Dentalium texasianum, Conus sp., and Fasciolaria lillium.

In an accompanying video (see http://www.youtube.com/nemastoma2#p/u/4/WLOXjFbw85s ) strong petroleum odors were pervasive when the dredge was retrieved from ~55 m depth at Ewing Bank 2 (Fish Haven) far west of the Deepwater Horizon Explosion; samples included individual carbonate nodules covered by light crude oil.

Deepwater macrocrustaceans and associated fauna dredged from ~250-1750 m depth with a benthic skimmer during this NSF RAPID cruise can be viewed at http://www.youtube.com/nemastoma2#p/u/1/c0B8SXZQZnQ.

A video highlighting Bryozoa collected during this RAPID cruise can be viewed at http://www.youtube.com/nemastoma2#p/u/2/8Mnh07sKWkk.

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.

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:

• Exploration
• expedition
• research
• sponges
• clay