John K. Reed, Stephanie Farrington, Patricia González-Díaz, Linnet Busutil López, Beatriz Martínez-Daranas, Dorka Cobián Rojas, Joshua Voss, M. Dennis Hanisak, Cristina Diaz, Mingshun Jiang, Michael Studivan, Andrew David, Felicia Drummond, Juliett González Mendez, Alain García Rodríguez, Patricia M. González-Sanchez, Jorge Viamontes Fernández, Marinos Daniel Estrada Pérez, Lance Horn, Jason White, Shirley Pomponi
A joint Cuba-U.S. expedition was conducted from May 14 to June 13, 2017 to map and characterize, for the first time, the extent and health of mesophotic coral ecosystems (MCEs) along the entire coastline of Cuba. Total ship transit around the island covered ~2,778 km (~1,500 nmi). Forty-three Remotely Operated Vehicle (ROV) dives at 36 stations confirmed the presence of MCEs habitat on all coasts of Cuba. ROV dives surveyed reefs from depths of 188 m to 18 m, covered 27 km, totaled 99 hours of bottom time, and resulted in 110 hours of highdefinition video. A total of 21,146 digital still images documented habitat and species, and photo transect images (7,248) will be used for future analyses of percent cover of benthic biota (corals, sponges, algae) and density of corals. The high-definition video will be used to document species composition and density of fish. 345 specimens of benthic macroinvertebrates and macroalgae were collected from mesophotic depths with the ROV, and 258 specimens from shallow snorkel dive sites; these will be used to verify taxonomy and assess population structure.
A total of 22 shipboard CTD casts were made around Cuba. Temperature and salinity data recorded by the ROV-mounted sensors showed surface temperatures ranging from 27.09 to 29.52o C for all dives. In general, temperatures were greatest along the south coast (29.52o C) and the coolest temperatures were found along the northeast coast (27.09o C). pCO2 ranged between 386-490 µatm, typically having highest values in the deepest zone, and the lowest values at depths between 80-120 m, and a second peak at 60-80 m. pH ranged from 7.95 to 8.10 with the lowest values being found in the deepest zone but with no clear pattern with depth in shallower areas. Aragonite saturation state was calculated, which ranged from 3 to 5, indicating a generally healthy carbonate chemistry condition over these reefs.
Topographically, the most consistently conspicuous features were the Deep Island Slope (125- >150 m), Deep Fore-Reef Escarpment (the ‘Wall’, 50-125 m), and Deep Fringing Reef (30-50 m). The Wall had the greatest diversity and density of macrobiota; nearly all vertical surfaces were covered with diverse sponges, algae, gorgonians, and black corals. A total of 424 taxa of benthic macroinvertebrates, 124 macroalgae, and 180 fish taxa have been identified to date from the surveys and from the collected specimens. These are preliminary results and taxonomy analysis continues. A total of 109 Cnidarian taxa (including, Scleractinia- 50, Alcyonacea- “gorgonians”- 32, Antipatharia- 15, Alcyonacea-Alcyoniina- 2) were identified. The deepest occurrences of zooxanthellate corals were Stephanocoenia intersepta (133 m), Agaricia sp. (122 m), and Montastraea cavernosa (101 m). Of these, Agaricia spp. were the most common corals, followed by M. cavernosa and O. faveolata. Agaricia was the most abundant scleractinian in the lower mesophotic zone, particularly from 50-75 m.
Cuban MCEs proved to be a very favorable habitat for marine sponges in both species richness and abundance. 297 distinct sponge taxa have been identified to date: 280 Demospongiae, 9 Homoscleromorpha, and 8 Calcarea, of which 115 (39%) were identified to species and 107 to genus (36%). The most frequently recorded species were the barrel sponge Xestospongia muta (shallow reef to 70 m), Xestospongia sp. Cu-1 (50-150 m), an encrusting unidentified bright yellow Verongiida (100-150 m), a large tubular Aplysina archeri, and several species of Agelas. A total of 124 taxa of macroalgae (48 Chlorophyta, 52 Rhodophyta, 24 Ochrophya, and 1 4 Cyanophyta) have been identified to date. The most frequently occuring taxa were crustose coraline algae (CCA), Halimeda copiosa, Lobophora spp., and species of Dictyota. A total of 149 species of fish have been identified to date from the ROV video. Between 60-150 m depths, fish diversity and abundances were low at all sites, whereas between 30-60 m the diversity increased, as well as the frequency and abundance of fish species. In the western region, sites that coincided with marine protected areas (Banco de San Antonio MPA, Guanahacabibes National Park, and Cayo Rosario MPA) showed a greater abundance of commercially important species: snapper (Lutjanidae), grouper (Serranidae), jack (Carangidae) and mackerel (Scombridae). The sites outside of marine protected areas had a lower abundance of these species, which could be an indicator of historical overfishing. Lionfish were observed at most sites but abundances were low compared to other Caribbean regions.
Regarding coral health, only 12 colonies of Scleractinia (mainly Agaricia sp.) out of 2,415 colonies that were recorded and annotated during the ROV dives (0.50%) showed signs of bleaching; one Agaricia had black band disease, and one had an unidentified disease. In general, the Cuban mesophotic corals appeared quite healthy compared to some other Caribbean reef sites. Lost or discarded fishing gear were relatively uncommon; in total, fishing line or long line were found at eight sites and one lost net was observed. In general, most dive sites appeared quite pristine with little signs of human impact.
This cruise report provides a preliminary overview of the oceanography, habitats, geomorphology, biozonation, biodiversity, and health of these reefs. Further analyses of the specimens, along with quantitative analyses of the video and photo data, will allow a more precise characterization of the diversity and relative abundance of the mesophotic communities of Cuba, as well as a better understanding of the connectivity of Cuban reefs with the Sister Sanctuaries in the U.S. and elsewhere in the Caribbean. In addition, Appendix 6 provides a detailed characterization of each dive site which will provide benchmark data for comparisons with future studies and the effects of climate change.
Reed, John, Stephanie Farrington, Patricia González-Díaz, Linnet Busutil López, Beatriz Martínez-Daranas, Dorka Cobián Rojas, Joshua Voss, M. Dennis Hanisak, Cristina Diaz, Mingshun Jiang, Andrew David, Felicia Drummond, Michael Studivan, Juliett González Mendez, Alain García Rodríguez, Jorge Viamontes Fernández, Lance Horn, Jason White, Shirley Pomponi. 2017. Cuba’s Twilight Zone Reefs: Remotely Operated Vehicle Surveys of Deep/Mesophotic Coral Reefs And Associated Fish Communities of Cuba, Joint Cuba-U.S. Expedition, R/V F.G. Walton Smith, May 14- June 13, 2017. NOAA CIOERT Report to NOAA Office of Ocean Exploration and Research, 510 pp. Harbor Branch Oceanographic Technical Report Number 183