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MESOPHOTIC CORAL ECOSYSTEMS – A LIFEBOAT FOR CORAL REEFS?
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MCEs are found worldwide in tropical and subtropical
waters. The existence of corals at mesophotic depths has
been known since at least 1889, when Darwin reported
the discovery of corals at depths of 128 m (Darwin 1889).
However, it was not until the 1960s and 1970s that direct
observation of MCEs began in earnest (Starck and Starck
1972, Wells 1973). As deep-diving technologies have
advanced and been adopted by scientists, so has our ability to
access and study MCEs. This chapter takes an in-depth look
at some of the MCEs that have been studied to date (Figure
3.1) and demonstrates that while there are commonalities
among MCEs, there are also differences; just as the shallow
coral reefs of the Great Barrier Reef are similar but different
from those found in the Florida Keys.
The MCEs discussed have a wide variety of geomorphologies.
They include MCEs found on the edges of continental shelves
and far from land, such as the Great Barrier Reef and Pulley
Ridge in the Gulf of Mexico off the southwest Florida shelf;
submerged fringing reefs and banks, such as in theUnited States
Virgin Islands, the Main Palau Island group, Okinwa and the
Gulf of Carpentaria in Northern Australia; canyon walls, such
as Eilat in the Red Sea; and insular island shelves and submerged
karst topography found in the Hawaiian Islands. Each MCE
described below provides a snapshot of what is known about
it, the dominant species present, any known limiting factors
(e.g. sedimentation, temperature and terrigenous input) and
any known impacts (e.g. hurricanes and El Niño Southern
Oscillation), as well as whether there is a management regime
in place. These case studies show the influences on MCEs and
that there is still a lot to learn about them.
Mesophotic coral ecosystems
examined
3.1.
Introduction
Chapter 3.
Figure 3.1.
Location of MCE case studies.
Mesophotic coral ecosystem case studies
Palau Island Group
Pulley Ridge, Gulf of Mexico
La Parguera, Puerto Rico
U.S. Virgin Islands
Eilat, Red Sea
Great Barrier Reef
Gulf of Carpentaria
Hawaiian Archipelago
Ryukyu Archipelago, Japan