FIXAREEF2:
Japan
- France
joint research project on marine cyanobacteria , 22 nov - 30 nov
2004
|
Cette
action s'inscrit pour l'ur099, dans le sous projet CYANOREEF |
Context
|
St
Gilles reef
Trou d'eau
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This
expedition is part of the « Japan-France joint research
project on marine cyanobacteria » approved by the oceanography
sub commission. The participation of L. Charpy was financed by
this commission managed for the French side by IFREMER and of MJ
Langlade by the Shizuoka university.
A
first French-Japan expedition (FIXAREEF 1)
was carried out in November
2003 in
the frame work of the “Chemical and Biological study in coral reef
around
La Reunion Island
: Biogeochemical cycling related to the bleaching of coral" (CBSCRReu)
A
workshop was done in Marseille in March 2004 to interpret data and
to prepare the next expedition.
|
|
A
special session of the 10th international coral reef
symposium was organized by B Casareto (Japan) and J Blanchot (IRD)
focusing onto the
plankton- benthos
relationship in coral reef ecosystems with a special focus on
cyanobacteria. A keynote lecture was also presented by Loïc Charpy
on the role of cyanobacteria in coral reefs ecosystems. During this
symposium, the participants of the programme have prepared a proposal
for the next expedition taking into account the recent advances in
coral reef studies which appeared during the symposium.
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Objectives
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Main
: C and N
cycle in coral reefs ecosystems.
Partial
:
-
Quantify
the nitrogen fixation and CO2 uptake by phytoplankton and
phytobenthos (cyanobacteria and others)
and characterize nitrogen fixing organisms
-
Quantify
the C, N and P exchanges between the reef and overlying waters
-
Quantify
the production, respiration and calcification of the reef
-
Quantify
the grazing of phytoplankton by coral reef community
-
Quantify
the grazing of benthic cyanobacteria by fish
-
Quantify
the water exchanges between lagoon and ocean
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Participants
and measured parameters
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Yoshimi
SUZUKI,
Shizuoka
University
(Japan)
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|
>
Leader of the CBSCRReu
>
DOM
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Beatriz
CASARETO,
Shizuoka
University
(Japan)
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>
Pigments by HPLC 0.2µ, 2µ
>
N2 fixation by coral rubble
>
Nano/Micro Pk
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Yoshiu
ISHIKAWA, (Japan)
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>
Ca
budget
>
Natural fluorescence by benthic communities (Diving
Pam)
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Hiroyuki
FUJIMURA, Univ.
of the Ryukyus, Okinawa
(Japan)
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>
Physical
parameters + alkalinity
> in situ reef metabolism
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Loïc
CHARPY, IRD Marseille
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>
N2
fixation
>
cyanobacteria
grazing
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Marie
José LANGLADE, IRD Marseille
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>
Data base
>
N2
fixation
>
cyanobacteria
grazing
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Isabelle
BIEGALA (not in the field)
IRD Marseille
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>
Characterization of N2 fixing organisms
by molecular probes
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Jean
BLANCHOT, IRD La Réunion
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>
picoplankton
>
pico grazing
>
in situ reef metabolism
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Yves
MONTEL, IRD La Réunion
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>
Chl 10µ, 3µ, GFF
>
Nutrients
>
in situ reef metabolism
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Pascale
CUET, University of
la Réunion
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>
Nutrients
>
pico grazing
>
in situ reef metabolism
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Patrick
FROUIN, University of
la Réunion
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>
pico grazing
>
in situ reef metabolism
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Dorothée TADDEI,
student University of
la Réunion
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>
in situ reef metabolism
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|
Manu,
student University of
la Réunion
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>
Current measurements
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| Flora MAZZEO, student University of
la Réunion
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>
in situ reef metabolism
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| Gwen , student University of
la Réunion
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>
in situ reef metabolism
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| Marc , technician, ECOMAR |
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>
in situ reef metabolism
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| Catherine TOURRAND |
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benthic
communities
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| Odile NAIM |
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benthic
communities
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Site
Trou d'eau,
St Gilles- La saline
La Réunion
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We
choose the site of “Trou d’eau” located in the
marine park close to St
Gilles because of :
-
a
good background (ECOMAR publications),
-
the
good health of the coral reef community (marine
protected area),
-
the
shallowness of the water (
1 m
deep),
-
and
the proximity of the ECOMAR laboratory (St Gilles harbor)
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Operations
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In
situ reef metabolism
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For
objectives 2-3-4 we have observed the exchanges of
matter between overlying waters and coral reef
communities. We measured water characteristics
upstream and downstream of a rich coral reef area.
The water displacement was evidenced by using a drug
(orange fruit). Two 24h cycles has
been done (24/25 nov 2004 and 9/10 dec 2004) , with
a total of 27 transects (upstream and
downstream). |
 |
We
expect to:
-
quantify
the reef production, respiration and calcification by
using the O2, DIC, alkalinity and Ca budgets
between the upstream and downstream stations,
-
quantify
the global import and export of matter by using POM, DOM, Nutrients
budgets,
-
quantify
the grazing impact of reef community by using
chlorophyll and cell abundance budgets.
The
water circulation in the lagoon and reef flat is studied by the deployment of current meters.
C
and N fluxes incubations
|
|
For
objective 1, benthic
and planktonic cyanobacteria was incubated in the presence
of 15N2 and 1
3C
during 12 and 24 hours :
from
18 h to 6 h (12 h night time), from
18 h to 18 h (24 h daylight and night). |
For
plankton
We
use bottles of 2000 ml, in triplicate = 9 bottles in total
We
add 4 ml of 15N2 and 4ml of
NaH13CO3
(purity 99.9%, 10 g/l)
For
benthos
We
use bottles of 130 ml. All incubations were performed in
triplicate.
We
add 0.26 ml of of 15N2
and 0.26 ml
of NaH13CO3
(purity 99.9 %, 10 g/l).
For
molecular
tools
Organisms
were collected onto
47 mm
0.2 µm. At the end of the filtration, the vacuum has been
removed and 5 ml of ethanol (
-20°C
) added to the filter and let 10 min. The ethanol has been
removed with a gentle vacuum and the filter stored in a
petrislide at
-20°C
.
Some
benthic organisms have also been filtered with the same
treatment.
For
benthic
cyanobacteria biomass estimation
The
biomass of benthic cyanobacteria has been evaluated along
transects from the beach to the reef flat.
Grazing
by fish
For
objective 5 , Visual
observations (snorkelling) of coral reef fish behavior was done.
Water
exchanges between lagoon and ocean The
exchanges of water between lagoon and ocean was estimated by
measuring the currents outside of the lagoon.
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Future
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A
special web page in
restricted access is dedicated to a common database for all the
partners from Japan, La Réunion and Marseille.
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