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Marine
environment under attack: coral bleaching reported
By Herman Belmar
Colours
are fading fast from some Caribbean coral reefs. Some are turning
completely white, as if soaked in household bleach - thus the
term 'bleaching'. Students and teachers of the UNESCO Sandwatch
group are monitoring the situation in Bequia, St. Vincent and
the Grenadines, with a sense of despair, not having any ready
answers or solutions. They have taken the proactive step of bringing
the problem to the attention of the St. Vincent and the Grenadines
Fisheries Division and guiding them to areas under serious threat.
Coral
bleaching, easily visible to the snorkeler, is a serious threat
to the delicate ecological balance of our marine environment,
specifically our coral reef. The white colour is due to the loss
of the symbiotic, single celled, algae zooxanthellae that
normally live within the tissues of coral animals.
Coral
bleaching is nothing new to the region. We were affected by the
first Caribbean mass bleaching on record in 1987 and 1988, and
additional bleaching which developed in 1989, 1990 and 1995. At
that time the bleaching spread geographically and in extent, with
animals affected from the surface to 200 feet. There was optimism
that the cycle was broken, since in a number of locations, the
recovery of some species even in the nearshore regions of SVG
looked quite promising.
What,
Why and How?
The
present hopelessness stems from the inconclusiveness as to the
cause of the current situation that from observation seems to
be affecting Brain Coral, Star Coral, Finger Coral and some soft
coral (Sea Whip) only. To quote Brown and Ogden as published by
UNESCO in the book Caribbean Coral Reefs, Sea Grass and Mangrove
Sites by Bjorn Kjerfve: 'The decade long die back of coral
in the Caribbean is a little understood, potentially pathogenic
condition operating on a long time scale. There is also evidence
of a synergistic interaction between natural and anthropogenic
causes. For example when coral started bleaching throughout the
Caribbean in 1987, there was speculation that coral under stress
from terrestrial sediment input showed a greater tendency to bleach,
although the primary factors appeared to be abnormally high or
prolonged summer seawater temperatures.'
It
is speculated that bleaching may be cause by unusually high temperatures,
by increased ultraviolet radiation possibly due to ozone depletion,
or by secondary pathogens after physical stress; or by some combination
of these. There is no doubt in my mind that we have had very hot
and dry summers for the last two years. In the other hand the
number of days with high runoff and sedimentation has been relatively
low.
While
the latter is true we must also be aware that terrestrial sediment
is increasing due largely to the bad practices of denuding the
hillsides as more and more houses are built without any or very
little contouring practices. These bad practices open the way
for agricultural chemicals, pesticides and inorganic fertilizers,
along with phosphates and chlorine from our laundry to reach the
marine environment. None of these additives are friendly to coral
life. We are only guessing, for just as we have no definitive
answer as to the cause of the massive fish kill the region suffered
a few years ago, or answers to the limited fish kill the east
coast of Bequia suffered in July/August 2003, we have no answers
as to whether these events are interconnected with the bleaching
problem. Whatever the cause, we know the delicate balance is threatened.
Fishing
Practices
Our
fisher folk should take note, for their livelihood is at stake.
Their normal practices can lengthen the recovery period, thus
adding further stress. There is a noticeable absence of predatory
and pelagic species of fish from our nearshore reefs as well as
the larger herbivore varieties, as some of these are the choice
fish for the export market. Spearfishing, small net size, gill
nets (which should be illegal), and fish traps with small mesh
are raping the area of the very species of fish we are hoping
would eat the algae and allow new coral to form new colonies.
Bleached
coral would already have died by the time the problem becomes
visible. This exposes the vulnerability of the reef ecosystem
in a variety of ways. The dead coral heads quickly become hosts
to algae that are presently in great abundance. Algae-encrusted
coral heads do not allow new colonies of coral polyps to settle
and develop, thus remaining dead for long periods. Some fish species
that are dependent on the coral disappear and the coral stones
which are normally cemented to the seabed by the growing coral
become loose and ready to be propelled onto the coastline by storm
surges.
Our
Backyard
Visitors
to Petit Nevis need not be reminded of the huge stone wall that
was demolished by Hurricane Lenny when huge waves hurled dead
brain coral heads over 50 feet inland, destroying everything that
was in their path. On October 28th 2003 this writer, who does
not profess to be a marine biologist, observed the first changes
in a prominent brain coral just outside La Pompeye Bay in Bequia.
By December 23 2003, the problem had taken root. Most of the Brain
Coral, Star Coral and Finger Coral in the area are seriously bleached.
Some soft coral are also affected. I am happy to report that the
Staghorn and Fan Coral varieties that have been making a comeback
do not appear to be affected at this time.
The
long term effect on tourism and fishing is not easy to measure
at this time, yet we hope that it would be minimal and that the
problem is short lived. To quote one of our visitors from Santa
Barbara, California who has been snorkelling on our reefs for
fourteen years 'St. Vincent and the Grenadines has a special world
class resource in their coral reefs, and these are becoming rare
and endangered.' We would hope that the problem can be corrected
and the pristine condition would return soon.
Our
marine environment is definitely under attack from pollution of
many sorts, nearshore fishing and now coral bleaching. How much
this fragile ecosystem can sustain at this time is anyone's guess.
As I dare to say, if definitely appears that we do not have the
resources to analyse the situation and the means to correct it.
What can we do? Youth to the rescue!
For
more information on the Sandwatch Programme contact humpback_1952@yahoo.com
Caribbean
Compass, March 2004
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