Submersible investigation of unconfirmed western Miami Terrace habitat with Nova Southeastern

Full report and featured report excerpts prepared by Brian K. Walker, Ph.D., Nova Southeastern University Oceanographic Center, June 8th, 2015. Full report is available for download at the bottom of this post.

On June 5, 2015 Nova Southeastern University joined Brownies Global Logistics (now Global Sub Dive) team on the new Project Baseline vessel, the R/V Baseline Explorer, to conduct submarine reconnaissance operations on the Miami Terrace. Previous mapping data from a variety of projects have limited information on the extent of the western hardbottom edge of the Miami Terrace and the organisms that inhabit the area (Figure 1). 

There presently remains a one mile gap of uncharacterized seafloor between the two mapping effort and the southern area remains “probable”. Therefore we conducted a submarine dive in this area to confirm the “probable” habitat and possibly show a connection between the two mapping efforts.Map  

The largest organism encountered was one Leiopathes black coral colony over one meter tall with several other species (crab, zooanthid, and an unidentified fish) living in the branches. Leiopathes was not documented in this habitat in the previous surveys. This finding is quite significant because it has extremely slow growth rates (<5 µm year -1) and the longest known life span of any skeletal accreting marine organism (Roark et al. 2009). Previous studies have shown these corals can live over 4000 years. Given its large size, the coral we found is likely over 1000 years old and possibly much older. 

The sub traversed approximately 400 meters along the seafloor at approximately 760 ft and verified that the Low Slope Inner Terrace Platform exists in the “probable” habitat polygon and continues to the north. The benthic communities were not visually different throughout the dive and were similar to both previous studies indicating the habitat likely continues between the two maps. The Leiopathes black coral colony found was likely extremely old and the first documented in that habitat. Its location will be provided to managers for conservation measures and to hopefully be avoided in any future plans.
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Miami Terrace Project Baseline Sub Dive Report - June 2015.pdf1.32 MB
Project Baseline has been at the forefront of increasing awareness of Florida reef decline as well as monitoring the health index for nearly 70 marine and freshwater environments world-wide since 2009. Watch as Project Baseline takes CNN underwater for special media coverage on Florida reefs - http://www.cnn.com/videos/us/2016/06/26/florida-dying-reefs-sanchez-nd.cnn