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MESOPHOTIC CORAL ECOSYSTEMS – A LIFEBOAT FOR CORAL REEFS?
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What are mesophotic coral
ecosystems?
2.1.
Introduction
Chapter 2.
Elaine Baker
, GRID-Arendal at the University of Sydney, Australia
Kimberly A. Puglise
, National Centers for Coastal Ocean Science, U.S. National Oceanic and Atmospheric Administration (NOAA), USA
Patrick L. Colin
, Coral Reef Research Foundation, Palau
Peter T. Harris
, GRID-Arendal, Norway
Samuel E. Kahng
, Hawai‘i Pacific University, USA
John J. Rooney
, Joint Institute for Marine and Atmospheric Research, University of Hawai‘i at Mānoa and NOAA Pacific Islands Fisheries Science Center, USA
Clark Sherman
, University of Puerto Rico at Mayagüez, USA
Marc Slattery
, University of Mississippi, USA
Heather L. Spalding
, University of Hawai‘i at Mānoa, USA
MCEs are dominated by light-dependent coral, sponge and/
or algal communities that live in the middle light (‘meso’ =
middle and ‘photic’ = light) zone. MCEs have often been
referred to as the coral reef ‘twilight zone’ because they
represent the transition between the brightly lit surface
waters and the perpetually dark deeper depths. They are
Figure 2.1.
MCEs can form on high-angle continental and insular slopes as illustrated here, or on low-angle outer insular shelves and on
the tops of submerged banks. Decreased light penetration rather than reduced temperature appears to be the primary limiting factor
controlling the depth distribution of MCEs at most locations (Kahng et al. 2010).
30 m
90 m
150 m
60 m
180 m
120 m
Shallow surface reefs
“Upper”mesophotic coral ecosystems
“Lower”mesophotic coral ecosystems
Approx. limit of most recreational scuba diving
Shallow reefs dominated by scleractinian corals
Decrease in light intensity
Lower range for most research diving with mixed-gas equipment
Upper range for most research using deep-diving vehicles
Depth in metres
The mesophotic coral ecosystem
Source: Richard Pyle, unpublished data.