Biotech News - Biocomplexity - Scientists look to the Bahamas as a model

Scientists look to the Bahamas as a model for coral reef conservation

One of the greatest challenges facing marine ecologists today is
finding innovative ways to reverse the rapid decline of coral reef
ecosystems around the world. Ten percent of the planet's reefs
already have been degraded beyond recovery, according to one survey,
and another 60 percent could die by 2050, primarily because of human
activities, such as pollution, overfishing and climate change.
The situation is particularly acute in the island nations of the
Caribbean, which have seen an 80 percent decline in coral cover in
recent decades. To address this crisis, an international team of
researchers, in consultation with the government of the Bahamas,
launched the Bahamas Biocomplexity Project--an interdisciplinary
approach to ecosystem management that project leaders say could
serve as a model for coral reef conservation worldwide.

"The Bahamas Biocomplexity Project works across various disciplines
to understand the intricate scientific and socioeconomic factors
contributing to ecosystem changes," said project principal
investigator Dan Brumbaugh, senior conservation scientist at the
American Museum of Natural History's Center for Biodiversity and
Conservation.

"Under the rubric of 'biocomplexity,' our approach recognizes that
natural and human systems are inextricably linked, and that analyses
and solutions must therefore transcend traditional disciplinary
boundaries," he added.

On Feb. 20, Brumbaugh and Fiorenza Micheli, assistant professor of
biological sciences at Stanford University's Hopkins Marine Station,
moderated a symposium entitled "Coral Reef Ecosystems and People in
The Bahamas: Practical Applications of Biocomplexity Science" at the
annual meeting of the American Association for the Advancement of
Science in St. Louis. Panelists included educators, social
scientists and marine biologists, who provided a progress report on
how biocomplexity science, still in its infancy, is being applied to
the problem of coral reef ecosystem management in the Bahamas.

The Bahamas model

"In 2000, the Bahamas committed to setting up a network of new no-
take reserves," said Brumbaugh , who is also a visiting scientist
with the National Oceanographic and Atmospheric Administration's
Marine Protected Areas Science Institute. "Starting with the
declaration of five new reserves, the country initiated a process
that was intended to lead to a system of protected areas covering 20
percent of their marine environment."

He pointed out that in 2002, new marine parks were added to the
national park system, which is managed by the Bahamas National
Trust, a non-governmental organization.

"This policy setting, along with interest from Bahamian partners in
having more scientific input for their decision making, set the
stage for researchers to try to look at how to best design a network
of marine protected areas," he explained. "Marine protected areas
provide promising, though sometimes contentious, tools for the
conservation and recovery of coral reef ecosystems. Contributing to
the heat of these discussions is the fact that apart from the most
direct effects of reserves, we really don't have a very good
understanding for how these complex systems will perform over time."

The Bahamas Biocomplexity Project was designed to address the
problem by adopting a holistic approach to marine conservation, he
said. In addition to using scientific tools--such as satellite
imagery, underwater surveys and population genetics--project members
conduct ethnographic and economic surveys to assess local attitudes
toward conservation, as well as educational outreach to explain
their findings to local stakeholders and decision makers.

"Interdisciplinary collaboration across oceanography, population
genetics, community ecology, anthropology and economics is providing
new insights into the relevant scales of planning for biodiversity
conservation and fisheries sustainability," Brumbaugh said. "Only
now are we starting to see some of the emerging lessons."

Predators, prey and seaweed

The project's most widely publicized finding to date was a study
published in the Jan. 6 issue of the journal Science written by
Peter Mumbry of the University of Exeter in Britain and a large team
of collaborators, including Brumbaugh and Micheli. The study focused
on the Exuma Cays Land and Sea Park, which, like other Caribbean
coral reefs, was struck by a mysterious disease in 1983 that
virtually wiped out a species of sea urchin that feeds on algae. The
urchins had played a vital role in the reef ecosystem by controlling
the spread of seaweed.

Since coral larvae only grow on rocks or dead corals that are algae-
free, too much seaweed can prevent corals from re-establishing
damaged reefs in the aftermath of hurricanes and other deadly
events.

With the urchins gone, the job of chief seaweed grazer was taken
over by a colorful herbivore known as the parrotfish. Parrotfish, in
turn, are preyed upon by large carnivores, such as the Nassau
grouper, whose numbers had increased in the park since the
imposition of a fishing ban in 1986. Today, according to the Science
study, Nassau grouper is seven times more abundant inside the park
than in three comparable areas elsewhere in the Bahamas.

But did the grouper population explosion occur at the expense of the
parrotfish, and therefore to the benefit of algae? For parrotfish,
the answer depends on which species. Researchers found that small
species were smaller than usual inside the reserve, suggesting that
grouper predators were picking off the largest members of their
populations inside the park.

In contrast, the number of big parrotfish--species 10 inches or
longer, too large for a grouper to swallow--increased inside the
park, apparently in response to protection from fish traps. The
study concluded that seaweed grazing in Exuma had doubled because of
the burgeoning population of big parrotfish, resulting in a fourfold
reduction in algal abundance compared to areas outside the park.

"The Science results suggest that parks protecting fishes may also
have beneficial effects on corals, by enhancing grazing and thereby
contributing to the ability of reefs to bounce back from
disturbances." said project co-principal investigator Micheli. These
results highlight the inherent complexity of life on reefs, she
added.

"There is this idea of redundancy in ecological systems: You lose
one species, but another replaces its function," Micheli said. "In
the case of grazers, 90 percent of urchins in one system were
depleted, but their function was replaced by parrotfishes.
Unfortunately, when you look at these small communities in the
Bahamas, there may only be a couple of species that have
interchangeable functions. Too often the boundaries of reserves are
drawn without having all of the necessary details about species and
habitats. Right now we're looking at what combinations of habitats
you need to protect to maintain the full set of ecological
processes."

Coral villages

In his AAAS presentation, project co-principal investigator Stephen
Palumbi discussed the genetics of marine habitats from the point of
view of corals--tiny animals closely related to sea anemones that
are responsible for building the reef framework. "We're looking at
the organisms that make the reef, because without them, the
organisms that use the reef wouldn't have a home," said Palumbi,
professor of biological sciences at Stanford's Hopkins Marine
Station.

He and his colleagues focused on staghorn corals, which used to be
common throughout the Caribbean: "We asked, Where do baby corals
come from, and from how far away can a healthy reef seed the
recovery of a damaged reef?"

To answer these questions, the Palumbi team compared the DNA of
staghorn corals collected from nine reefs, some just a few miles
apart, others separated by about 600 miles of ocean. "We look for
where the genetic barriers are," he said. "That tells us where the
larval barriers are. Our results show that genetic family lines can
be quite distinct on reefs as close as two kilometers (1.2 miles),
so they're not co-mingling over short distances. All reefs in our
study more than 500 kilometers (300 miles) apart were genetically
distinct. Coral families thus seem to exist in local villages, with
little genetic exchange above the scale of 50-100 kilometers (30-60
miles)."

This finding led Palumbi to raise another question: "If you have a
reef damaged by hurricanes, dynamite or sedimentation, how quickly
would you expect it to reseed? The answer: perhaps in thousands of
years."

Some marine ecologists advocate restoring dying or damaged reefs,
but that approach is rarely cost-effective, he argued.

"You can collect sprigs of coral, grow them in an aquarium, then
return them to a reef, but transplanted corals are easily killed,"
Palumbi said. "Maybe 1,000 out of 10,000 sprigs will grow, but with
a growth rate of about one centimeter per year, it would take many
years to get big. It's expensive, and not particularly successful.
From a management standpoint, the genetics tell us that each island
has to husband its own coral garden."

Human dimensions

"Better understandings of the dynamics of coral re-establishment and
species interaction are crucial, but these are only parts of the
puzzle," said project co-principal investigator Kenny Broad,
assistant professor at the University of Miami's Rosenstiel School
of Marine and Atmospheric Sciences.

"How reserves may affect the local human communities that rely on
these fishing grounds must also be considered," Broad told the AAAS
symposium. "Will fishers shift effort toward other fishing grounds
that may then suffer similar environmental consequences? Might they
switch to activities and fishing methods even more damaging to the
environment once their livelihoods are threatened? Given the lack of
enforcement that exists in many parts of the world, how can local
groups play a role in developing innovative approaches for managing
the resources that they rely upon most directly?"

Such questions are being addressed by social scientists working
within the Bahamas Biocomplexity Project, he noted: "Our results in
the Bahamas as elsewhere suggest that rigid top-down directives that
lack local support will not be effective in protecting or restoring
coral reef ecosystems."

Other presenters at the AAAS session were Richard Stoffle of the
University Arizona; Alan Hastings of the University of California-
Davis; and Karen St. Cyr of the Bahamas Ministry of Education, now
on sabbatical at the University of Massachusetts. Stoffle described
details of his work with communities in the central Bahamas and
their views about marine reserves. Hastings discussed general
theoretical guidelines for reserve network design, highlighting some
of their intrinsic complexities, and St. Cyr addressed integrating
marine research and scientific results into education.

Several presenters highlighted the need for flexibility and special
consideration of local context, including history, economics,
cultural values and opportunities for advancing ecosystem-based
management. For example, public education and involvement--through
the formal school system and community workshops, where locals share
their ecological knowledge and researchers share their understanding
of the sustainability of ecosystem services--may contribute to wider
acceptance of ecosystem-based management.

"The parks and marine reserves in the Bahamas are enormously
thoughtful and successful, but when you visit there it seems
natural, because so much of it is submerged," Palumbi said. "They
realize there is a special relationship between the people and the
sea. Tourism, which is about 60 percent of the gross national
product, is based on environmental protection. But the Bahamas isn't
unique. It's one of several countries, including St. Lucia, Curacao,
Australia and South Africa, which has established the goal of
setting aside 20 percent or more of its marine ecosystem. It's not
that these countries are so far ahead, it's just that the United
States is so far behind."

###
By Mark Shwartz

The Bahamas Biocomplexity Program is primarily supported by the
National Science Foundation and includes 11 collaborating
institutions: American Museum of Natural History, Bahamas Ministry
of Education, Bahamas National Trust, College of the Bahamas, Perry
Institute for Marine Science, Resources for the Future, Stanford
University, University of Arizona, University of California-Davis,
University of Exeter and University of Miami's Rosenstiel School.

COMMENT:
Daniel Brumbaugh, American Museum of Natural History, Center for
Biodiversity and Conservation: (831) 420-3963 or (831) 234-4378
(cell), brumba@amnh.org

Fiorenza Micheli, Stanford University Department of Biological
Sciences: (831) 655-6320, micheli@stanford.edu

Stephen Palumbi, Stanford University Department of Biological
Sciences: (831) 655-6210, spalumbi@stanford.edu

Kenny Broad, University of Miami, Rosenstiel School: (305) 421-4851,
kbroad@rsmas.miami.edu

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