Patch reefs: Lidar morphometric analysis

Alina Reef is one of several thousand patch reefs that lie across the shallow carbonate platform seaward of Hawk Channel off the northern Florida Keys. The site is near the northern latitudinal fringe of the late Holocene western Atlantic coral reef distribution (Figure 1). The area is covered by calcareous sand and discontinuous Thalassia testudinum seagrass meadows and is studded with numerous scattered Holocene patch reefs. Most of the patch reefs are found in water depths of 2–9 m, are subcircular, elliptical, or irregular in plan view, and range up to about 8 m in vertical relief and 700 m in width. Coring has demonstrated thicknesses of 4.5–6 m and has revealed frameworks built by large, massive head corals.