[Coral-List] Praslin Island data request
adriencheminee at yahoo.ca
Mon Aug 27 19:04:37 EDT 2007
I am back from a field work
on the north coast of Praslin Island, Seychelles. I studied there a
portion of the coast, mapping and characterizing the main benthic assemblages from
the shoreline to the open sea: seagrass meadows, inner reef slope; reef flat
and front, outer reef slope.
I performed underwater transects
(snorkelling) in order to validate the preliminary cartography I obtained from
aerial pictures and previous studies. I gathered observations of percent cover
along those transects in each benthic units.
Unfortunately I couldnt perform
LIT transect (GCRMN) as I wished, because of climatic conditions. However the
first transects provided me with interesting data.
I wish to compare it with
similar data : I wonder if any of you would have previously observed data regarding
this area, in order to have baseline on which I could rely, with which I could
compare my data, or at least better understand the dynamic of the site, and
potential evolution trends:
percent cover of scleractinian corals and seagrass
ratio of coverage by algae/corals
associated abundances of reef fishes, ratio adults/juveniles,
record of coral mortality events,
- Impact of the 2004 tsunami ? (I observed many
broken corals, rubble field, and many of the coral colonies where young,
with small sizes and high vitality (see hereunder))
For memory here is a summary
of my main observations:
Mixt seagrass meadows : Total % cover : ranging from
50 to 90%, with Syringodium isoetifolium (50 to 60 %), Halodule
uninervis (15 to 30 %) and Thalassia testudinum (10 to 20 %)
Inner reef slope : macroalgae (50 to 70 %
cover) : genus Sargassum, Turbinaria, Padina (also Halimeda and Penicillus) ; and scleractinians (0 to
10% cover) : genus Pocillopora (P. damicornis et P.
verrucosa), Acropora and Fungia ; vitality 80%.
Reef flat :
o Inner reef flat : macroalgae (<5%
cover) : Halimeda and Penicillus, Sargassum and Turbinaria ;
and scleractinians (<5% cover) : genus Pocillopora (P.
damicornis and P. verrucosa), Acropora and Fungia ;
Reef front : macroalgae (15% cover, locally
70%) : Turbinaria and Sargassum ; and scleractinians : (10
to 50% cover, locally 100%) : Acropora , Pocillopora (P. damicornis and
P. verrucosa) vitality 50 to 80 %.
Numerous broken dead branching and tabular Acropora, Many small young colonies of Pocillopora and digitated Acropora (<30cm diameter)
Outer reef slope :
First type: macroalgae (50 to 70 % cover) : Sargassum
; and scleractinians : (5 to 15 % cover) Pocillopora (P.
damicornis and P. verrucosa), digitated Acropora; vitality
Second type: reduced macroalgae cover (0 to 50 %
cover) : Sargassum, Turbinaria ; and more scleractinians (15 to 20
% cover) : Pocillopora (P. damicornis and P. verrucosa),
digitated Acropora; Acropora divaricata, Porites, Montipora, Favites, Favia, vitality
80%. Locally 100% cover on granite submerged blocks).
Many thanks for any comments and advices,
mel : adriencheminee at yahoo.ca
adresse : 6160 route Bellec 13100 Aix en Provence, France
tel: (+33) 6 81 73 95 19
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