83 / 100
MESOPHOTIC CORAL ECOSYSTEMS – A LIFEBOAT FOR CORAL REEFS?
83
In comparison to their shallow-water counterparts, very
little is known about MCEs. MCEs have been understudied,
not due to their lack of importance, but because of the
difficulty in accessing them with conventional technologies.
The upper limit of the mesophotic zone, at 30–40 m, is too
deep for scuba diving on air, while the lower limit of the
mesophotic zone is too shallow for deep-diving technologies
(e.g. submersibles and large remotely operated vehicles) to be
used effectively and efficiently. Consequently, approximately
two-thirds of light-dependent coral reef ecosystems remain
largely unknown (Pyle 1996b, 2000, Feitoza et al. 2005,
Puglise et al. 2009).
Although the study of MCEs has increased exponentially
in the past 30 years — with the adoption of mixed-gas and
closed-circuit rebreather scuba diving by scientists and the
development of smaller remotely operated vehicles and
autonomous underwater vehicles — there are still large gaps
in our scientific knowledge. In 2008, the
First International
Mesophotic Coral Ecosystems Workshop
(12–15 July in Jupiter,
Florida, USA), organized by the U.S. National Oceanic and
Atmospheric Administration and Geological Survey, brought
together scientists and resource managers for the first time to
discuss and review the state of knowledge regarding MCEs
(Puglise et al. 2009, Hinderstein et al. 2010). The workshop
resulted in three significant advances in improving our
understanding of MCEs: (1) an agreed definition for MCEs
(see text box), (2) a
Mesophotic Coral Ecosystem Research
Strategy
, which identified critical management information
needs (Puglise et al. 2009), and (3) a special MCE-themed
section of the journal
Coral Reefs
(volume 29, number 2,
pages 247–378) that reviewed what was known about these
ecosystems (Hinderstein et al. 2010). By 2014, the MCE
research community realized that there was a need for a
Second International Mesophotic Coral Ecosystems Workshop
to evaluate developments made in knowledge since 2008.
Following the second workshop held by the Interuniversity
Institute for Marine Sciences (26–31 October 2014 in Eilat,
Israel), a special MCE-themed section of the journal Coral
Reefs (volume 35, number 1) was developed, which highlights
the latest MCE research efforts and identifies information
gaps and priorities for future MCE research (Loya et al. 2016).
The two workshops made it abundantly clear that there is
a growing body of work on the topic of MCEs and that the
scientific community has made progress in gaining visibility
for MCEs. This is best evidenced by searching peer-reviewed
journals (using the Aquatic Sciences and Fisheries Abstracts
database) for the term “mesophotic coral”. Search results show
that before the first workshop was held in 2008, the term
“mesophotic coral” was used only once, but it has been used
in over 55 publications since 2008. This change is the direct
result of scientists coalescing around the term MCEs for these
ecosystems.
MCE visibility has improved within both the scientific
and management communities, and scientists are making
incremental improvements in our understanding of these
ecosystems. However, there are still large gaps in our
understanding of MCEs, especially in comparison with
our knowledge of shallow reefs. The best way to close these
information gaps is to focus research efforts on answering
questions that are critical to enabling resource managers
to make informed decisions about MCE protection and
conservation. For MCEs, the most crucial information
is what scientists refer to as “baseline information”. Key
questions include: where are MCEs located? What controls
where MCEs are found? What organisms are found in MCEs?
What ecological role do MCEs play? What are the impacts
from natural and anthropogenic threats on MCEs? Are MCEs
connected to shallower reefs and can they serve as refuges for
impacted shallow species?
Understanding mesophotic coral
ecosystems: knowledge gaps for
management
7.1.
Introduction
Chapter 7.
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
Mesophotic coral ecosystems
are characterized by
the presence of light-dependent corals and associated
communities typically found at depths ranging from 30–40 m
and extending to over 150 m in tropical and subtropical
regions. The dominant communities providing structural
habitat in the mesophotic zone can be comprised of coral,
sponge, and algal species (Puglise et al. 2009, Hinderstein
et al. 2010).
Mesophotic coral ecosystems definition