Reefs At Risk

[Les Kaufman]

Dear Steve and Phil and everybody,

Reef decline appears to have been widespread in the tropical west Atlantic
over the past two decades.  Most prominent is the reduction in prevalence
of acroporid corals, and increase, in many places, of macrophytes.  Belize
was unusual in that when the acroporids began to vanish, there was an
endemic agariciid (absent elsewhere in the region) that could serve as a
partial functional replacement, and it did.

Since the original high-coral coverage condition is more highly valued than
what we are seeing more of today, it would undoubtedly be most productive
to:

        1.  appreciate natural trends toward regeneration, and their scaling
        2.  judge whether natural regeneration is satisfactory
        3.  develop interventions that facilitate and accelerate regeneration
                on the largest spatial and smallest temporal scales possible.

Let us presume that Step 2, the regeneration rate concommitant with the
passive approach to reef conservation, is not sufficient to offset rates of
degradation in Florida.  Note that whether this is or isn't the periphery
of reef growth doesn't matter.  All that matters is that reefs can grow
here and it is worth some effort to see that they do.  Then we must move on
to Step 3.

Step 3 implies aggressive perturbation (some would call it "restoration")
experiments.  Looking about, I dont' see a great many such experiments in
progress.  Kudos to Richmond and Mueller and their people.  What are we
doing to adapt and expand their methodologies?  What capabilities do we
need at our disposal?

        A.  ability to upregulate grazing pressure
        B.  ability to downregulate nutrient inputs
        C.  ability to force-recruit corals on a large scale

My own guess is that grazing pressure in Florida is pretty high (though
perhaps the ability to force-recruit Diadema would be helpful on a local
basis); and that if nutrients are a major issue, we are already doing what
we can to reduce the inputs.  That means, shouldn't we be looking harder
and more seriously than we are at option "C?"  This option offers a
wonderful probe of the resiliency of the system....if healthy live corals
appear on the reef but do not survive, then something probably must be done
with A or B, or there is a food web problem with coral predators, otherwise
give up on reefs altogether for now because it's a large-scale
environmental health issue that must be addressed first.

Since acroporids and agariciids are the principal corals with response
times and growth rates commensurate with human intervention, should they
not be the principal focus of efforts toward C?

It would be really helpful if we could reach some consensus on this.  No
one strategy is sufficient to conserve Florida's reefs, but we should be
coming up with a clear and articulate definition of the top-priority
conservation science and methodologies needed to do the job...and we
aren't, unless I've missed something.

Monitoring IS important, but only in the context of adaptive management.
What are our goals?  What shall our complete litany of interventions be?
What room have we left ourselves for trial and error?  Are the intervention
experiments well designed and sufficiently powerful to serve our needs?

The alternative is to reduce human impacts as much as possible, and then
watch and wait.

These are two very different, complementary strategies.

What combination of these do we, as a community, advocate?

Les Kaufman
Boston University Marine Program
Department of Biology
Boston University
5 Cummington Street
Boston, MA 02215

e-mail: lesk at bio.bu.edu
phone: 617-353-5560
fax:   617-353-6340


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