[Coral-List] Biodiversity extinction
dfenner at blueskynet.as
Sat Jan 30 04:55:04 EST 2010
When people find new species, these are species that are new to us, but
they were there all the
time. They didn't just evolve in the last few weeks or years. They are
species that people hadn't found, or hadn't recognized. Many are "cryptic"
so they may be rare, physically hidden, very small, camouflaged, or just so
similar to known species that nobody noticed the difference before. You are
definately correct that new marine species are found vastly much faster than
extinctions are discovered, but the new species are not ones that have just
evolved recently in our lives, so they don't balance extinctions.
There are vastly more species out there on reefs than we have
cataloged. There are various ways of estimating total numbers of species,
and they may produce different estimates, but they all agree that the total
is vastly larger than the ones we have found and cataloged. The largest
number of species known from any one reef system presently to my knowledge
is New Caleldonia where about 8500 species are known. The names alone fill
a book an inch thick, names only, no descriptions, photos, etc. But the
estimates are that coral reefs around the world may have up to a half
million species on them. So almost all of them are not yet known.
Indeed, the question of whether there are fewer extinctions in the
oceans than on land is one that has been debated. The oldest view is that
the oceans are so large that it's resources including organisms, are
undepleteable. That has clearly been demonstrated not to be the case
(unfortunately). Demonstrating the extinction of a species is not easy. It
is essentially the null hypothesis, proving something doesn't exist
anywhere, so it
is impossible to totally prove. So one view is that in the oceans, it is
just nearly impossible to demonstrate that something no longer exists
anywhere. I believe that in general a species isn't declared extinct until
it has not been found for 50 years. By then it is a bit late to try to
conserve them, so we have to do something while they are decreasing. I read
recently that 107 species (none marine) have gone extinct in the U.S. while
were being reviewed for Endangered Species Status. That is an example of
management failure, and comes from gross underfunding of the agencies
responsable for researching the status of the species. The IUCN Red List
has a standard set of criteria by which information on species can be
evaluated, to estimate danger of future extinction. The criteria were put
together by experts on extinction. A recent review of all the world's reef
coral species found many to be threatened. One coral species has been
have gone extinct, a fire coral on the Pacific coast of Panama, due to the
1983 El Nino mass bleaching event, which killed all 2000 or so colonies
known to exist of that species. Eventually another smaller group of
colonies was discovered, and then all 100 of them were killed in the 1998 El
bleaching event. Most recently, the species has been found in a coral
collection from Indonesia, so presumably it is not extinct.
Reviews of marine extinctions have in some cases documented a variety
of apparent extinctions, but some are only local extinctions, and some are
near-extinctions, with a very few individuals left known. But even with
those added, the numbers are still small. Is that because the oceans are so
big it is hard to extinguish a species? Or is it because the oceans are so
big it is hard to find the information to show that species have gone
extinct? Not an easy question to answer.
Back to "biodiversity," there are lots of different measures of
biodiversity, the total number of species in existance on the whole planet
is just one measure. There are indices of biodiversity that can be applied
locally, and they can decline even without a species being totally lost,
just by the evenness of species being reduced. So if you go from 100
species all equally abundant, to 100 species where 99 are extremely rare,
and one totally dominates the ecosystem, biodiversity has been reduced.
That is likely to be the kind of reduction of biodiversity that happens in
the earlier stages of the destruction of coral reefs, unless the agent of
destruction is highly selective for some species. All destructive agents
are likely to be at least partly selective, so for instance bleaching kills
some species much more readily than others. Certainly it caused a local
extinction of that firecoral in Pacific Panamal without causing the
extinction of other corals. White band disease in the Caribbean is
sufficiently specific to Acropora to cause massive losses of Acropora there
which led to the Acropora species being listed as Endangered Species. Local
extinctions can be a microcosm of global extinction. Local extinction of
bumphead parrotfish on some islands in Fiji by spearfishing has been
documented. Further, there are species on reefs that are endemic, that is,
restricted to small areas. Those species can be particularly vulnerable to
extinctions. An example might be several species of toadfish, a couple
known only from Belize, one known only from Cozumel. Many reef species have
wide dispersal, but a few don't. I get a chuckle when I read a paper that
says that reef fish all have a larval dispersal phase. Sharks and rays
certainly do not have a larval dispersal phase, nor do most toadfish, or the
Bangaii Cardinal, or handfish (a type of angler that mostly lives in
Tasmania, OK, not a reef area, but some species are endemic to a just one or
The extinction of species on land is well documented, and as I
understand it, the rates of extinction due to humans are on the same order
magnitude as that during the great extinction events of the geological
Dept Marine & Wildlife Resources
Carleton JT (1993) Neoextinctions of marine invertebrates. American
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Carlton JT, Geller JB, Reaka-Kudla ML, Norse EA (1999) Historical
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Carpenter, K. E., Abrar M., Aeby G., Aronson R., Bruckner A., Delbeek C.,
DeVantier L., Edgar G., Edwards A., Fenner, D. and 29 others. 2008. One
third of reef building corals face elevated extinction risk from climate
change and local impacts. Science 321: 560-563.
Culotta E (1994) Is marine biodiversity at risk? Science 263: 918-920.
Dulvy, N. K., Polunin, N. V. C. 2004a. Using informal knowledge to infer
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Dulvy, N. K., Sadovy, Y., Reynolds, J. D. 2003. Extinction vulnerability
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Fenner, D (2001) Mass bleaching threatens two corals with extinction.
Reef Encounter 29: 9-10
Glynn, PW, Feingold JS (1992) Hydrocoral species not extinct. Science
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Payri, C. E. and B. Richer de Forges (eds), Compendium of marine species
from New Caledonia. Documents Scientifiques et Techniques II7, Institute de
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(2000) Assessing and protecting endangered marine species. ICES Journal of
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----- Original Message -----
From: "R.D." <scubadivingdoc at yahoo.com>
To: <Coral-List at coral.aoml.noaa.gov>
Sent: Friday, January 29, 2010 8:57 AM
Subject: [Coral-List] Biodiversity extinction
> As a non-academic with field experience in coral conservation, coral
> disease, and marine park science and politics, I would like to comment on
> the recent Biodiversity extinction post, keeping in mind the "big
> In the past few years several scientific biodiversity expeditions have
> reported in the lay press the discovery of thousands of new marine species
> from the Phillipines to Antartica to Australia to Tasmania to New Guinea
> and on and on. Such species have been scientifically collected, catalogued
> and classified. A Google search for "new marine species" yields a treasure
> trove of articles.
> On the other hand, an internet search for recently extinct marine
> species(especially credited to human influence) reveals sparse data.
> Therefore, when a scientist speaks about "stopping the loss of
> biodiversity" and "continued biodiversity extinction" it seems incongruous
> to the reported facts. Is there scientific data to confirm this loss?
> Which species have been lost and how many? When we talk about habitat
> destruction, anthropogenic global warming, and overfishing, is there
> scientific data to confirm a "loss of biodiversity"? Or is it an
> assumption that it has happened or will happen?
> It is my understanding that environmental stressors rarely destroy an
> entire species(except for mass extinction events). In fact it is often
> environmental changes that allow new mutations to take hold and encourages
> the development of new species. As an example, a 2007 scientific survey of
> the Celebes Sea turned up between 50 and 100 new species of fish and
> invertebrates in an area that has been isolated by rising sea levels.
> So my question is,"Is isolated habitat destruction on coral reefs really
> contributing to loss of biodiversity?" Is there scientific evidence?
> Or is the following analogy appropriate - If my entire neighborhood
> poisons all of the ant hills in our back yards, are we contributing to the
> loss of biodiversity? Will poison-resistant ants develop? Will different
> species of ants move in? Will the same species relocate from other areas?
> I hate to see human induced damage to coral reefs as much as anyone. But
> loss of coral cover does not equal extinction of species.
> And if you are going to try to convince the general public otherwise, you
> will need to show them what species we have lost and how they have helped
> cause that loss. Because as of now, for every marine species put on the
> endangered list, there are hundreds or thousands newly discovered.
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> Coral-List at coral.aoml.noaa.gov
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