Are
Coral Reefs Dying?
Over
recent months a number of news stories and scientific
studies have reported that coral reefs are in widespread
global decline from human impacts and in particular from
global warming. That reefs in many areas are being
adversely affected by local human populations is
observable. How serious this is and what portion of
reefs are seriously affected is however much less clear
and probably to some extent exaggerated.
Coral reefs in one form or another have been around
for some 500 million years and even some present day
reefs have histories going back over 50 million years.
This is an incredibly long span of time. Our own
evolution from ape to modern human has been a long slow
process but still it has taken place in only about 5
million years. Most present day genera of corals have
histories going back tens of millions of years and
several first appear in the Cretaceous period around 100
million years ago. Eocene fossils of many types of
fishes and other reef creatures from 50 million years
ago are very similar, often even indistinguishable from,
present day species.
During much of their existence reefs have
flourished in a world that was more tropical than it is
now. The bleaching events that are being widely touted
as threatening reefs with extinction generally involve
water temperatures only a degree or two above normal. It
is difficult to believe that reef communities have
persisted for so long within a degree or two of their
extinction when in fact during much of that time the
Earth was warmer than at present. So, what is going on?
Since the beginnings of recorded history
predictions off imminent catastrophe have been a
perennial feature of humanity. Despite a track record of
near total failure such predictions never seem to lose
their appeal, neither to would be prophets nor to an
audience willing to believe them.
Science, despite it’s attempt at skeptical
rationality, is no exception. Proclaiming serious
problems results in attention, recognition and research
funds. It also generates fads of interest in, and
acceptance of the reality of, the claimed problems. In
the 1950s and 60s the marine science community was
promoting their endeavor with the promise of untold food
and minerals from the sea. This promoted a lot of
funding but little return. Then in the 70s and 80s
environmental concerns began to be widely recognized and
the failed promises of loot and plunder from the sea
were quickly dropped for concerns over saving them. This
too required lots of money for research but didn’t
entail the inconvenient necessity of delivering
anything. Success could always be claimed whenever no
real problem eventuates and if it does that only
indicates the necessity for more funding.
Despite the muddle of misinformation, exaggeration,
promotion and herd following it is undeniable we live in
a finite world and it cannot sustain growing human
impacts forever. One of the biggest difficulties we face
is distinguishing reality amid a confusing welter of
imagination, beliefs and misinformation. Failing to do
so presents us with an impossibly large range of
“problems”, misdirects effort, impedes sensible use of
resources, and generates increased demand elsewhere.
What we don't get from one place we make up for in
another.
With regard to the condition of reefs here are some
facts to consider:
In the entire world, throughout history, there has
only ever been one reef species that has been
exterminated by humans, this was the Caribbean monk
seal.
Although clearly associated with higher than normal
water temperatures, coral bleaching regularly occurs at
temperatures that are below what the same corals
tolerate in other areas. Recent research has revealed
that a number of different species of algal cell live in
association with corals and these algae have differing
temperature tolerance. The number and kind of algae can
vary seasonally in the same coral colony and they differ
in different areas. This explains how the same coral in
one place can tolerate temperatures that cause bleaching
in another and indicates an as yet un-assessed degree
of ability to adjust to different temperatures.
Whether or not the recently observed bleaching is
unprecedented is not known. Extensive surveys of central
Pacific reefs in the Early 1970s found some reefs with
shallow water corals mostly dead but in place. This was
assumed then to be due to Crown-of-Thorns starfish
infestations but it now seems more probable that a
severe bleaching event may have been the cause. A study
just published using isotopic analysis of age and
temperatures from corals in the eastern central Pacific
has found that the strongest (i.e. highest temperature)
El Niño event for the past 1000 years was in the 1600s.
So too, a generally ignored effect of global
warming would of necessity be a latitudinal expansion of
the oceanic region available to corals.
The Great Barrier Reef of Australia with its nearly
350,000 Km² of reef and lagoon area makes up about 30%
of the world’s total reef area. It is also among the
most pristine of reef areas. Distance, weather and a
relatively small population mean most of the GBR is
rarely even visited . Of the 2900 reefs in the complex
only a few dozen are regularly used for tourism and the
total annual fish harvest of 17 Kg per Km² is less than
1% of what reefs elsewhere commonly sustain. The total
commercial and recreational reef fish harvest for the
Barrier Reef currently only comes to some 6000 metric
tons annually. This is similar the what the Florida Keys
produces from less than 1% of that area of reef and
lagoon. It is also less than half of Australia’s own
production of farmed salmon from a few bays in Tasmania.
Elsewhere in the remote vastness of the Pacific and
Indian Oceans there are many many reefs in healthy
condition.
Even in S.E. Asia, East Africa, and the Caribbean
where reefs are most heavily impacted many healthy reefs
still remain and are the mainstays of a multi-billion
dollar global recreational dive industry. Dive tourism
has not only made healthy reefs an important economic
asset but also assures that any significant
deterioration will not go unnoticed.
Although the situation is never be as good as we
might like it is seldom as bad as we may fear. Neither
complacency nor despair is warranted but a healthy level
of skepticism is, especially when mass media and
“expert” opinion is involved.

Walter Starck
Editor/Publisher
wstarck@goldendolphin.com |