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The AAPG/Datapages Combined Publications Database

Environmental Geosciences (DEG)

Abstract

DOI: 10.1306/eg.01121615013

A statistical approach to assessing relief on mesophotic banks: Bank comparisons and geographic patterns

Paul W. Sammarco,1 Lance Horn,2 Glenn Taylor,3 Daniel Beltz,4 Marissa F. Nuttall,5 Emma L. Hickerson,6 and G. P. Schmahl7

1Louisiana Universities Marine Consortium, 8124 Hwy. 56, Chauvin, Louisiana 70344; [email protected]
2Undersea Vehicles Program, University of North Carolina at Wilmington, 5600 Marvin Moss Lane, Wilmington, North Carolina 28409; [email protected]
3Undersea Vehicles Program, University of North Carolina at Wilmington, 5600 Marvin Moss Lane, Wilmington, North Carolina 28409; [email protected]
4Louisiana Universities Marine Consortium, 8124 Hwy. 56, Chauvin, Louisiana 70344; [email protected]
5Flower Garden Banks National Marine Sanctuary, National Oceanic and Atmospheric Administration, 4700 Avenue U, Bldg. 216, Galveston, Texas 77551; [email protected]
6Flower Garden Banks National Marine Sanctuary, National Oceanic and Atmospheric Administration, 4700 Avenue U, Bldg. 216, Galveston, Texas 77551; [email protected]
7Flower Garden Banks National Marine Sanctuary, National Oceanic and Atmospheric Administration, 4700 Avenue U, Bldg. 216, Galveston, Texas 77551; [email protected]

ABSTRACT

Substrate relief is a common characteristic of hard-bottom offshore banks and is associated with benthic biodiversity. Earlier studies revealed varying relief associated with offshore mesophotic communities. Correlations may exist between relief and benthic biodiversity, which in turn may be useful in determining drill sites. Such drill site determination requires obtaining an estimate of variability in relief on these banks and its associated geographic patterns. We performed fine-scale surveys of relief on 14 banks in the Gulf of Mexico to examine variation between them, geographic patterns, and possible processes influencing them: 28 Fathom, 29 Fathom, Alderdice, Bouma, Bright, Elvers, Geyer, Horseshoe, McGrail, Parker, Rankin, Rezak, Sidner, and Sonnier Banks. We used a multibeam sensor on a remotely operated vehicle, with resolution of approximately 0.5 m (2 ft). Average and standard deviation of relief were calculated at the transect, drop site, and bank levels of resolution. Sidner and McGrail Banks had the highest relief, and 29 Fathom and Sonnier had the lowest. Sidner Bank had relief averaging up to 11 m (36 ft) in height, whereas 29 Fathom Bank exhibited the lowest relief (range 1 to 2 m [3 to 7 ft]). Bright Bank and all others exhibited intermediate and variable relief at both the transect and drop site levels. Relief is not predictable on many banks because of high variability between drop sites. Some low-relief banks are predictable in their relief, lending themselves to predictions of benthic diversity and suitable drill sites. Relief decreased significantly as one moved northward in the study region. Relief exhibited a significant sinusoidal pattern from west to east. Banks with low relief occurred off Lake Calcasieu and Lafayette, Louisiana.

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