Pulley Ridge, Gulf of Mexico, USA

Abstract

Pulley Ridge is a limestone ridge that extends nearly 300 km along the southwestern Florida shelf in the eastern Gulf of Mexico. The southern terminus of Pulley Ridge supports a mesophotic coral ecosystem (MCE) at depths of 59–105 m and is the deepest known photosynthetic coral reef off the continental United States. The biodiversity consists of 95 species of macroalgae, 92 demosponges, 18 octocorals, 17 scleractinian corals, 9 antipatharian corals, and 86 fishes. Twenty managed fishery species occur at Pulley Ridge including red grouper, and since 2010 the lionfish population has dramatically increased. The dominant scleractinian corals are plate like corals of the family Agariciidae (Agaricia spp. and Helioseris cucullata), Montastraea cavernosa, Madracis spp., and Oculina diffusa. The percent cover of benthic biota averaged 49.9% over all regions of Pulley Ridge, and macroalgae were dominant (46.5% cover). Scleractinian corals averaged 1.5% cover and sponges had 1.2% cover. In the past 10 years, the Pulley Ridge MCE had a substantial loss of scleractinian coral. The percent coral cover on the Main Ridge dropped from 12.8% in 2003 to 0.9% by 2012–2015, a 93% loss of coral. However, recent surveys show the majority of corals to be relatively healthy; only 1.21% of the colonies counted (38,368) showed signs consistent with “white syndromes” disease. The prevalence of disease on Pulley Ridge is relatively low compared to the Caribbean. The factors causing the decline of the coral communities at Pulley Ridge between 2003 and 2012 are unknown.