Porites - coral as building material

Abigail Moore abigailyacl at yahoo.com
Thu Aug 1 03:06:51 EDT 2002

Dear Michael and other coral-listers
I only replied swiftly to Ron with a very brief input
in order to provoke comments!
I would like to add input to your reply, and see what
other people have to say. In paticular I would like to
invite members who have experience with or contructive
thoughts about  the problem of the use of corals as
building materials  and related matters to contribute
their thoughts to this list.

 ?Surely the wharf- and sea-wall building activities
of the Bugis and Badjo have already cleared more
corals from those shores than could possibly be used
in septic tanks...?

True, the activities of the Bugis and Bajo, plus many
other ethnic groups and a number of government
projects have indeed used much coral for building
purposes ? and thereby degraded or destroyed vast
areas of reef. Indeed, the volume used is probably
much greater than that used for sceptic tanks.
However, the fact that much coral has already been
destroyed is not really a reason for being ?blasé?
about current and future destruction ? or is it? And
are large-scale destructions a reason for ignoring
other, smaller impacts? If we look at it this way, we
should only concentrate on, say, bombing and allow all
other destructive practices to go on unchecked.
Conditions now are such that any extra pressure could
be ?the straw that breaks the camel?s back? for corals
in a particular area, if not world-wide.
In areas where public health campaigns focus on
sanitation, or re-building is in progress, amounts
used only for this purpose can be significant in
relation to the remaining living coral reef area. If
the corals taken (usually at the same time) for
foundations are added to those used in the sceptic
tanks, in some locations we are talking about amounts
definitely capable of significant impact.
I feel we should widen this issue to the use of coral
as a building material more widely, an area which is
often given little attention in comparison say to
destructive fishing, but is often very significant

?Porites is the most "porous" of the Scleractinians,
hence its name. It would make superbly absorbent
tank-linings: but the stuff is going to leach right
through. Because the septic waste itself will leach
right through a Porites wall/lining, there will be all
sorts of public health implications. It will be an
educational problem, but: light-aggregate (coral
rubble) concrete tanks make excellent holding
vessels?.. I agree that this is a problem, but the
reefs of Sulawesi face larger challenges than being
used as septic tank materials-most of them receive the
same material, in somewhat more dilute form, whilst
still alive...check out the extent of damage of the
raw sewage plume from Manado.?

Actually I am not at all sure all coral used is
porites, people here take whatever there is! However,
this technical information is most interesting, and it
points out that the very reason people like the stuff
is the reason why it is NOT suitable! I am not a
sceptic tank engineer, nor are the people using the
stuff. They only know that they want ?modern?
faciltities and do not want over-flowing tanks.
Generally there are no sceptic tank emptying services,
so that when a tank is full, people will build another
if there is avaialable land. Main drains and waste
collection are still a ?pipe dream?, litterally!

No-one I have seen uses concrete, as it does indeed
?hold?  the waste, which is just what no-one wants! I
have to say I thought that the sewage would probably
ferment and leach out in at least ?semi-treated? form,
but maybe we do need specialist information on what
really happens.. and what impacts it has for health
and nutrification etc. I would imagine that even leaky
sceptic tanks are likely to provide more of a buffer
than the prevalent discharge of raw sewage, not just
in Manado! But at what cost to the reef?

If people could be persuaded that tanks should ?hold?,
is use of coral rubble as an aggregate a good idea?
For sure, there is plenty available, but is it a good
idea to have people collect it, or will this also
increase the often already serious coastal abrasion
problems? I don?t know the answers.

?It is against the law, throughout Indonesia, to
collect live corals for this or any other purpose-so
there is an enforcement problem?.

Too right, I agree! What can we do about it?

There are so many ?good? laws to protect the
environment, but so little enforcement. Few people are
aware of the actual law, even fewer have any idea why
there is a law, and most who are aware know that ?the
law is for sale?, usually quite  cheaply compared to
the costs of legal alternatives. That goes for most
ilegal activities, not just ?coral mining?.

No one guards the sea. Coral is there for the taking,
all you nened is a crowbar and small sampan canoe, and
safe. If people want to take from a quarry on land,
they will have to get permission and pay, plus
delivery can be a problem. In some cases conflicts (eg
Poso) even make access to quarries life-threatening
for coastal people. Most often those in a position to
prevent or at least discourage such activities ?turn a
blind eye?, afraid of being seen as
?anti-development?, even if in some cases they are

VERY few people at any level actually know that coral,
especially massive coral, is alive - to them it is a
rock like any other. So to them, what is the problem?
Only afterwards they find out about abrasion, loss of
fisheries etc. Both are very real problems in parts of
the Bay of Palu area for example, in some locations
largely due to coral mining, a not-insignificant
portion for sceptic tanks for houses in and around the

Now, the use of corals in building may be relatively
minor overall compared to some issues, but is of real
significance in certain areas, and is likely to
continue to increase in scale as people?s expectations
rise. Not just for sceptic tanks, but as more and more
people transfer from wooden to more permanent
structures, coral, however illegal, is actually
increasingly used.

So, should we be working on the authorities to enforce
the rules they make, or building ?awareness? in the
minds and hearts of coastal people (village and city
dwellers), or both? What information and advice should
we be giving them?

OK, we need enforcement. And awareness. Both to
back-up lobbying for enforcement, and in the meanwhile
to attempt to influence the users, for each use we
need to know answers to at leat two questions: why not
(from their viewpoint ? not the legal one)? and what
can be (realistically) substituted?

Best regards


Abigail Moore MSc
Yayasan Adi Citra Lestari
Palu, Central Sulawesi

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