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| NOAA's Undersea Research Program supports a range of
research projects that address the importance of corals for ecosystem
integrity, climate monitoring, and harvesting of marine resources,
among many other issues. There is a diversity of coral species that
live in many climates and at a range of depths throughout our Earth's
oceans. NURP's six regional centers are funding,
supporting and conducting research throughout the greater U.S. to
better understand the role of corals in the ecosystem. A range of
current topics include: Coral Reef Monitoring  NURP
supports several reef monitoring programs throughout the country.
For example, the National Undersea Research Center for the Southeastern
U.S. and Gulf of Mexico supports a coral reef fish assessment program
from which results have been used to establish MPA boundaries, baselines
and over-fished stocks in Florida Keys National Marine Sanctuary.
This program is part of the sanctuary's monitoring effort to evaluate
habitat condition and changes in the Sanctuary Preservation Areas
and Tortugas Ecological Reserve and is characterized by innovative
sample design statistics, rapid and detailed habitat assessments,
multidisciplinary participation (benthic and fish groups working together),
and timely publication of results. The program covers multiple habitat
types, nearshore to offshore, and results provided the baseline from
which marine protected areas and other reef habitats will be assessed
and monitored for many years.Coral Disease  The
most damaging disease killing corals in Florida and throughout the
Caribbean is white band disease (right), which affects the branching
corals in the genus Acropora and devastated populations long before
any research or monitoring programs were in place to document the
epidemic. Since then, additional diseases have emerged and the center
supported projects that produced major findings. Seminal work related
to blackband disease was published over the last ten years, including
a Nature paper that identified the first coral pathogen using Koch's
postulates and that also documented 40 percent mortality in some populations
of the elliptical star coral: the disease now affects nearly two dozen
other species. NURP is supporting other researchers who are also emerging
as leading figures in marine disease work, related to a fungal pathogen
that kills seafans. Results include learning that the fungal growth
rate is temperature dependent, with temperatures usually below its
growth rate optimum; this means, however, that almost any temperature
increase should result in conditions where the pathogen does better.
The pathogen is thus a "poster child" for an argument made
in a Science paper about climate links (warming) and diseases. Similarly,
the correspondence between a killing disease outbreak in a gorgonian
and widespread coral bleaching reinforces this point. Coral Bleaching  Coral
bleaching is an issue that has local, regional, and global significance,
but corals are not the only organisms to bleach on the reef. A long-term
program to assess the relevance of bleaching in foraminifera was pioneered
in the early 1990s through NURP research in Florida and has continued
throughout the decade. Forams contain a symbiont (diatoms vs. zooxanthellae
found in corals) and are sensitive indicators of environmental change,
including light, nutrients, and temperature. These studies point to
foraminifera as bioindicators for environmental assessment and monitoring
programs, and possibly as indicators of global change. Specific to
coral bleaching, a long-term program discovered substantial natural
and seasonal variation in the density of zooxanthellae in corals,
with bleaching resulting at one extreme when zooxanthellae densities
decrease to levels that can be detected by the eye. A main point of
this paper is that zooxanthellae density can decrease seasonally by
at least half, is not detectable by the human eye as a color change,
and does not necessarily progress to a full-blown bleaching "event."
This means that there is a lot more natural system variability than
was previously known. Another study documented that coral tissue itself
was surprisingly unaffected during two severe bleaching events in
consecutive years. And corals that bleached one year also bleached
the second year: this is important because there is an ongoing debate
that suggests coral bleaching may be adaptive, but results here suggest
otherwise.Coral Reef Sponge Ecology  Several
examples are provided that highlight ecological studies supported
by the center. It's probably not an understatement to say that researchers
working with the Florida program are rewriting the book related to
sponge ecology and coral feeding biology (not part of this summary).
For example, the importance of parrotfish predation on sponges was
discovered in a series of experiments that documented the selectivity
of sponge-eating fishes. When combined with new data on chemical defense,
these results have completely altered our view of sponge predation
on Caribbean reefs. The results have interesting management implications
because "indirect effects" or linkages between sponge-eating
fish and the benthos, due to the loss of certain predators or herbivores,
may alter the ecology of reef sponges to permit the growth of otherwise
cryptic species, some of which may more effectively compete for space
with corals. At least a dozen other publications resulted from work
on sponges to understand the chemical defenses of reef invertebrates
against predatory fishes and novel assay systems were used to identify
and isolate the responsible metabolites - some of which are being
tested for their pharmacological potential.
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Long-term
studies are underway to study the giant barrel sponge Xestospongia
muta, which has been called the "redwood of the reef"
for its size and supposed long-life. Like corals, specimens of X.
muta have recently been observed to bleach during summer months,
resulting in intense predation on bleached sponges by fishes and
presumed sponge mortality. Since 1997, monitoring of marked sponges
at permanent transect sites are used to investigate whether bleaching
is caused by high temperatures, changes in chemical defenses, or
reproductive status, and to gather demographic data. Early results
suggest that temperature is not a factor, and that most sponges
recover from bleaching events. Surprising outcomes include high
levels of pulsed recruitment of "baby" sponges, and rapid
recovery and regrowth of some bleached sponges. Finally, growth
rates of X. muta are difficult to determine, but may be faster than
originally thought. This monitoring program, along with several
long-term, manipulative experiments to test resource allocation
among growth, wound-healing, reproduction, and chemical defenses,
will require years of study before patterns become clear and are
only possible due to sustained funding and long-term commitments
that are not typical of most funding programs, but are none-the-less
critically important to advance knowledge of coral reef function
and structure.
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