USGS OF 2004-1228, Pulley Ridge Bottom Photographs; Introduction

Bottom Photographs from the Pulley Ridge Deep Coral Reef, OF 2004-1228

OF 2004-1228

Disc Contents

Introduction

Study Area
Bottom Photographs
GIS

Introduction to Pulley Ridge Study Area:

Pulley Ridge is a series of drowned barrier islands that extend over 100 km in 60-100 m water depths. This drowned ridge is located on the Florida Platform in the southeastern Gulf of Mexico about 250 km west of Cape Sable, Florida (Halley and others, 2003). This barrier island chain formed during the initial stage of the Holocene marine transgression approximately 7000 years before present. These islands were then submerged and left abandoned near the outer edge of the Florida Platform. The southern portion of Pulley Ridge, the focus of this study, hosts zooxanthellate scleractinian corals, green, red and brown macro algae, and a mix of deep and typically shallow-water tropical fishes. This largely photosynthetic community is unique in that it thrives with only 5% of the light typically associated with shallow-water reefs with similar fauna.

Several factors help to account for the existence of this unique deep-water community. First, the underlying drowned barrier island provides both elevated topography and lithified substrate for the establishment of the hardbottom community. Second, the region is dominated by the west edge of the Loop Current, which brings relatively clear and warm water to this area. Third, the ridge's position on the continental shelf places it within the thermocline which provides nutrients to the reef during upwelling (Halley and others, 2003).

This report presents the still photographs acquired during the April 2003 cruise aboard the Florida Institute of Oceanography's research vessel Suncoaster. These data are just one part of a multi-year study which includes the acquisition of sidescan-sonar imagery, high-resolution bathymetry, high-resolution seismic-reflection profiles, bottom video imagery, and bottom samples.