MEPS 559:45-63 (2016)  -  DOI: https://doi.org/10.3354/meps11883

Coral growth, bioerosion, and secondary accretion of living orbicellid corals from mesophotic reefs in the US Virgin Islands

D. K. Weinstein1,2,6,*, A. Sharifi1,3, J. S. Klaus1,2, T. B. Smith4, S. J. Giri1, K. P. Helmle5

1Department of Marine Geosciences, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
2Department of Geological Sciences, University of Miami, Cox Science Building, 1301 Memorial Drive, Coral Gables, FL 33124, USA
3Neptune Isotope Laboratory (NIL), Department of Marine Geosciences, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
4Center for Marine and Environmental Studies, University of the Virgin Islands, 2 John Brewer’s Bay, St. Thomas, Virgin Islands 00802, USA
5Oceanographic Center, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL 33004, USA
6Present address: Department of Chemistry, Biology and Marine Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
*Corresponding author:

ABSTRACT: Growth rates of the major Caribbean reef framework-building coral Orbicella spp. decrease with increasing water depth and light attenuation. However, reliable, spatially distributed growth rates for corals deeper than 30 m are rare, and the combined influence of coral framework accretion, secondary framework accretion, and framework macroboring on net framework calcification in these habitats is poorly constrained. To better understand the growth limits and spatial variability of Orbicella-dominated mesophotic coral reef ecosystems, live platy samples of Orbicella franksi were collected at 3 upper mesophotic reef habitats with varying structural characteristics on the Puerto Rican Shelf, south of St. Thomas, US Virgin Islands. Average mesophotic coral linear extension rates, determined by standard X-radiographic techniques and confirmed by stable isotopic analyses, were 0.80 ± 0.03 mm yr-1 (±SE), slower than previously recorded for Orbicella spp. at shallower US Virgin Island reefs. However, coral cover at 2 of the mesophotic reefs was considerably higher than at nearby shallow-water St. Thomas reefs, implying that fast coral growth rates are not necessarily needed to maintain Caribbean reefs with high coral cover and structural complexity. A probable reason for this is reduced bioerosion with depth. Rates of net coral framework calcification were significantly different between the neighboring mesophotic coral reef habitats, likely a result of the complex interplay between site variability in irradiance, nutrient availability, and other factors. Analysis also indicated that the influence of El Niño-Southern Oscillation on water circulation and salinity as well as on water clarity and nutrient distribution in the Caribbean is reflected in the annual variability of mesophotic O. franksi growth rates. Site differences in net coral framework calcification suggest a potential long-term mechanism for the production or maintenance of heterogeneous reef-scale geomorphology along broad-sloping carbonate shelves colonized with mesophotic coral reef systems.


KEY WORDS: Mesophotic coral ecosystem · Coral growth rate · Bioerosion · Secondary accretion · US Virgin Islands · Orbicella · Calcification · Skeletal carbon and oxygen stable isotope analysis · X-radiography · Density bands


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Cite this article as: Weinstein DK, Sharifi A, Klaus JS, Smith TB, Giri SJ, Helmle KP (2016) Coral growth, bioerosion, and secondary accretion of living orbicellid corals from mesophotic reefs in the US Virgin Islands. Mar Ecol Prog Ser 559:45-63. https://doi.org/10.3354/meps11883

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