Re. Brazilian reefs
rutabaga at pacwan.fr
Wed Jun 13 10:47:56 EDT 2001
It is always a pleasure for me to chat about brazilian reefs, even since I
did not visit them since 30 years...
Yes I worked for three years on the brazilian coasts, spending most of my
time in the region of Recife, where I was based. I visited most of the
reefs between Angra dos Reis(SP) south and Fortaleza (Cearà) north, with
very limited technical possibilities.
The first contact with brazilian reefs is very little appealing for the
newcoming coral student: some local geologists even pretend that there are
NO reefs at all but sandstone reefs or arrecifes ( lines of fossil
beach-rock), sometimes with a scarce coral cover. Such a position is both
understandable and wrong : understandable because brazilian reefs can by
no means be compared with caribbean or indo pacific reef barriers, but
wrong because no criterium of minimum thickness is required in the
definition of a coral reef : the criterium being the development of a coral
and coralline framework with an upward growth to the surface and resistance
to the waves, leading to characteristic morphology, both in surface and in
volume, which is the case in Brazil.
My observations from the sixties, led me to the following statements :
a) Differences between sandstone and coral reefs were clear cut and easy
to put into evidence by airborne, land and underwater observation. They can
be observed superposed or in parallel rows, their relative disposition
being linked to local coastal evolution in the Holocene).
b) When a true emerging coral reef-flat is considered, its upper surface
is dead since mid and late Holocene sea-level variations have been
extremely strong in that region, with several higher than present levels
between 6000 BP and present, so that the upper surface of the flats lies
presently about 1 metre above its normal "biological level". (i.e the
highest level where corals are presently living).
c) When seen underwater coral formations were already very poor in the
sixties for several reasons: first reason being the very low number of true
hermatypic coral and fire corals species involved in the building (about 20
species for the whole Brazil, of which only10 thrive on the Nordeste
reefs. Most noticeable is the presence of endemic Gorgonians, Sponges and
Corals(genus Mussismilia) and the absence of such important caribbean genus
as Acropora, Diploria, Colpophyllia, Solenastrea, Dendrogyra, Mussa,
Mycetophyllia and others..
d) In the Nordeste the living coral cover was generally lower than 50% in
the sixties.The rest of the surface was mainly covered by encrusting
corallines, sponges, endemic Gorgonians and very dense stands of Halimeda.
This was in part due to the very murky waters? Pollution from sugar cane
mills was already impoprtant, especially near the estuaries. I do not know
what it is presently, I heard from people in Recife that the situation was
not terribly worse, even with the (considerable)development of pollution.
I never observed coverages of living corals above 50% on the shallow water
reefs of the Nordeste ( from the surface down to about 20 metres), mean
coral cover was about 25% (this percent was estimated, not calculated).
Main reef-building species were, by order of decreasing importance :
Coralline algae, Millepora alcicornis, Mussismilia hartii, Siderastrea sp,
Montastrea cavernosa and Porites astraeoides, Halimeda leaves being also a
prime source of sediment.
The richest and more developed reefs were south of Pernambuco in the
islands of Abrolhos, in front of Caravelas (state of Bahia) which are
presently a National Park.
A few bibliographical references :
Van ANDEL, T & LABOREL, J. 1964, Recent high relative sea level stand
near Recife, Brazil. Science, 145, 3632,pp. 580-581.
LABOREL J.1965. Note préliminaire sur les récifs de grès et les récifs de
coraux dans le Nord est brésilien Recueil des Travaux de la Station Marine
d'Endoume,53, 37, : 341-344.
LABOREL J. 1967. A revised list of brazilian scleractinian corals with
description of a new species. Postilla, New Haven, 107, pp. 1-14.
KEMPF M. & LABOREL J. 1968 Formations de Vermets et d'Algues calcaires sur
les côtes du Brésil. Recueil des Travaux de la Station Marine d'Endoume,
43, 59, : 9-23.
LABOREL J.1969. Les formations de Madréporaires des côtes tropicales du
Brésil. (Thèse d'Etat de Sciences Naturelles) . Annales de l' Univiversité
d' Abidjan. E, 2, 3, 260p.
LABOREL J.1969. Madréporaires des côtes tropicales du Brésil,
Systématique, biologie, répartition, Annales de l' Institut
Oceanographique. Paris, nlle série, 47, 9, pp. 171-250.
SUGUIO, K.; MARTIN, L. & FLEXOR, J.M., 1977. Sea level fluctuations during
the past 6000 years along the coast of the State of Sao Paolo
(Brazil).Proceedings of the 10th. INQUA congress, (Birmingham).
MARTIN, L.; FLEXOR, J.M., BLITZKOW, D. and SUGUIO, K , 1985. Geoid change
indications along the Brazilian coast during the last 7000 years. Proc. 5th
Int. Coral Reef Congress, Tahiti, 3, 85-90.
>I have recently carried out a brief survey of Brazilian reefs in the
>Recife. If I am not mistaken, you worked there many years ago. I am very
>interested to know what conditions were like when you first visited,
>coral cover, but also fish diversity and abundance. The corals are almost
>completely dead now in the areas I saw. None of the scientists I contacted
>has any data or memory of conditions prior to the mid-1980s. All info and
>Gregor Hodgson, PhD
>Director, Reef Check Foundation
>Professor (Visiting), Institute of the Environment
>1652 Hershey Hall 149607
>University of California at Los Angeles
>Los Angeles, CA 90095-1496 USA
>Office Tel: 310-794-4985 Fax: 310-825-0758 or 310-825-9663
>Email: gregorh at ucla.edu Web: www.ReefCheck.org
Jacques & Francoise Laborel
Chemin des grands Bassins,13600 La Ciotat, France
tel. (33) 04 42 83 60 32
fax. (33) 04 42 71 81 68
e-mail : rutabaga at pacwan.fr
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