Mesophotic Coral Ecosystems of Puerto Rico and the US Virgin Islands

1. Mesophotic Coral Ecosystems of Puerto Rico and the US Virgin Islands Roy Armstrong, Ph.D. Bio-optical Oceanography Laboratory University of Puerto Rico at Mayaguez

2. Mesophotic Coral Ecosystems WHAT ARE THEY AND WHERE RE THEY FOUND? • Light-dependent coral ecosystems • Depths: from 30-40 m and extending to over 150 m • Found in tropical and subtropical regions • Dominant communities can be coral, algae, and sponge species

3. Penetration of Light in the Sea

4. Penetration of Light in the Sea In very clear oligotrophic waters:

5. Why Study Deep (Mesophotic) Coral Reefs? • In shallow waters (< 20 m) of the Caribbean Region, a coral decline of 80% over the last 30 years has been documented (Gardner et al. 2003). • Mesophotic reefs (> 30 m) are largely unknown. • They appear to be healthier than shallow water reefs. • Habitats of commercially important fish species. • Source of coral larvae for recruitment and potential recovery of the shallower reef areas. • There could be several times as much reef habitat deep as there is shallow.

6. 0 - 30 m 4325 56.7 30 - 50 m 1738 22.8 50 - 100 m 1562 20.5 Bathymetry of Puerto Rico -Virgin Islands Geological Platform Potential Reef Habitat

7. Examples of Mesophotic Coral Ecosystems Hind Bank MCD, US Virgin Islands Depth 40 m Desecheo Island, Puerto Rico Depth 80 m

8. The Seabed AUV The Seabed AUV was used in 2002, 2003, 2004 and 2008 to image and characterize mesophotic reefs in Puerto Rico and the U.S. Virgin Islands

9. Seabed Optical Imaging • Two Prosilica GC-1380C CCD cameras with 1360 x 1024 resolution • 12 bit dynamic range (0 - 4,095 grey levels) • From an altitude of 3 m, the images are 3.12 m wide by 2.3 m long, covering an area of 7.17 m2 • Spatial resolutions of 2.2 mm per pixel • A 150 Ws strobe provides the only source of illumination • Two cameras were used, a downward looking camera and a forward facing camera • Over 100,000 images of mesophotic reefs in the Puerto Rico Shelf since 2002

10. Forward-looking Camera Forward-looking camera image showing a red hind grouper (E. guttatus) (A) and enlargement of the fish (B)

11. Hind Bank MCD, U.S. Virgin Islands Found well-developed coral reefs with 43% mean living coral cover. Maximum coral cover was 70% at depths of 40 m. Dominance by M. annularis complex. Low diversity index (range 1.47 to 1.85).

12. 2003 – MCD PR-03 Transect Found well-developed coral reefs with 28 % mean living coral cover

13. Photo Mosaicking Seven images were used from a depth of 35 m measuring approximately 6.3 m long and covering an area of about 20 m2

16. Bajo de Sico - 64 m Large topographic feature off the west coast of Puerto Rico Mesophotic reef begins at 45 m and extends to about 100 m

17. Desecheo - 80 m “Sponge – coral bioherm” at depths of 40 to 100 m

18. Mesophotic Coral Ecosystems WHY ARE THEY IMPORTANT TO MANAGEMENT? • Extensions of shallower coral reef ecosystems • Potential refugia for impacted shallow-water species • Some species are endemic to this depth range • May serve as critical habitat for economically- and ecologically-important species Photo courtesy of Jorge Sabater.

19. Deep Sea Corals and Habitats