Coral
reefs (cont'd)
By
Marjorie Henry, Contributor
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| Students
of Charlie Smith Comprehensive
High School in discussion at the
launch of the PALS-Ministry of
Education publication 'Raising
Children to Resist Violence',
at the Gleaner Company, 7 North
Street, Kingston. - Andrew Smith
Photo |
A
HAPPY New Year to you all! I hope that
it will also be a very productive year
for you in so far as your academic achievements
are concerned. I do trust that you enjoyed
your Christmas holiday break from school.
At the same time, I hope that it was
not just all fun and frolic, but that
you took time out to do some review
of your lessons, particularly if you
are in the fifth form (or Grade 11).
No, I am not being a spoilsport. Instead,
I want you to bear in mind the fact
that you write your external examinations
in the next four to five months and
the holiday break provided you an opportunity
to do some study.
During
the later part of last term, I started
to review that part of the geography
syllabus, which comes under Geomorphic
Systems. The only topic done was on
coral reefs. Mr. Franklin McDonald,
retired executive director of the
Natural Resources Conservation Authority
(NRCA) raised some concerns about
the information given on threats to
coral reefs. This lesson was published
on November 22, 2005. As a result
of those concerns, I had discussions
with Rev. Peter Espeut. He is the
executive director of the Caribbean
Coastal Area Management Foundation,
Lionel Town, in Clarendon.
I
start this term's series of lessons,
then, by revisiting the topic. If
you are one of those students who
collect these lessons, my advice to
you is that you discard the former
lesson and replace it with this one,
which has new information. The lesson
then attempted to answer a question
which I will now restate:
'What
are the activities that can lead to
the destruction of coral reefs?'
Listed
below in order of importance, are
the activities that will result in
the destruction of coral reefs. You
will observe that they are primarily
human activities.
NUTRIENT
POLLUTION
The
growth of marine algae is encouraged
by the increased nutrients in the
seawater. These algae can suffocate
the corals. There are different sources
of nutrient pollution in seawater.
These include:
(a)
Fertiliser (NPK) that is used in agricultural
production. Excess fertiliser is washed
into the sea as runoff after rainfall.
(b)
Sewage is a source of nitrogen (N).
Domestic wash water from the kitchen
and laundry, where washing is done
with detergent, provides phosphorus
(P).
SEDIMENTATION
Improper
farming practices lead to soil erosion,
as does deforestation, construction
of buildings particularly on coastal
lands, marine construction and channel
dredging. All these activities that
lead to increased sediments ending
up in rivers and the sea after even
moderate rainfall. The sediments cause
turbidity in marine waters, which
reduces the sunlight available for
photosynthesis. They also smother
the reefs.
OVER-EXPLOITATION
BY FISHERMEN
This
is in specific reference to any herbivorous
creatures, that is, which eat plants,
specifically algae. As stated in the
first point above, an abundance of
algae can suffocate the coral and
the herbivores on the reefs maintain
the delicate balance between corals
and algae.
(a)
White and black sea urchins (sea eggs)
are very important grazers of algae
and remove them from the reef. In
several Eastern Caribbean countries
(especially Barbados, Dominica and
St. Lucia) there is a season where
white sea urchins are harvested and
eaten. Harvesting has not been sustainable,
and the sea urchin populations have
been in decline for some time, which
means that there has been a build-up
of smothering algae on their reefs.
On the other hand, we in Jamaica do
not eat sea urchins.
(b)
Herbivorous fish such as parrotfish,
doctorfish and, goatfish graze on
the algae and, therefore, remove them
from the reef. The removal of large
numbers of herbivorous fish will cause
the algae to grow on the coral and
smother it. Unfortunately, parrotfish
and goatfish seem to be choice fish
in Jamaica, which is bad news for
coral reefs. On the other hand, most
people in the eastern Caribbean do
not eat parrotfish.
(c)
Turtles and manatees also graze on
the algae. These sea animals are almost
extinct, which contributes to the
build-up of algae.
THE
EFFECT OF DISEASE
Although
we Jamaicans do not eat sea urchins,
some years ago almost all of our black
sea urchins were wiped out by disease,
which could have had some kind of
human origin. They are now beginning
to come back. There are also different
kinds of diseases which affect the
corals themselves, and some can be
of human origin. Corals eventually
die when diseased.
I
will continue with the topic in the
next lesson, as there is still some
more information to be shared with
you it.
I
close with a study tip:
'Set
a goal for each subject: A, B, or
whatever is realistic for you.'
*
Marjorie Henry is Geography teacher
at Glenmuir High School in Clarendon.
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