11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 19: Biogeochemical Cycles in Coral Reef Environments
19-17
Biochemical Symbiotic System in Corals : Role Of The Vitamin B12 Produced By
Coelenteric Bacteria
Sylvain AGOSTINI* 1 , Yoshimi SUZUKI 1 , Beatriz CASARETO 2 , Kazuyo SHIROMA 1 ,
Kazuhiro DAIGO 1 , Hiroyuki FUJIMURA 3 , M. F. M. FAIROZ 1
1 Shizuoka University, Shizuoka, Japan, 2 Laboratory of Aquatic Science, Shizuoka, Japan,
3 University of the Ryukyus, Shizuoka, Japan
Vitamin B12, cyanocobalamin and other analogues, is an essential factor for numerous
phytoplankton. Croft et al., Nature 2005, showed that 25 species of Dinoflagellates were
vitamin B12 dependent out of 30 studied . Until now all Animalia were found vitamin
B12 dependent. Even if Cnidaria were not specifically studied we can suppose that they
require it too. Vitamin B12 is known to be only produce by bacteria and is found at very
low level in seawater. Thus it is controlling the primary production in some oceanic area.
Unfortunately the levels, the role of vitamin B12 in Coral Reefs and the requirement of
the genus Symbiodium were never studied. The source of vitamin B12 in coral reefs was
investigated in Sesoko, Okinawa, JAPAN. Vitamin levels were measured in surface
water, pore water and coelenteric fluid of Galaxea fascicularis, sampled using a novel
technique. The measurement was done using radioassay (SimulTrac SNB) which was
optimized for analysis in seawater and in some case by HPLC. The highest
concentrations were found in the coelenteric fluid : 200-400 pmol l-1 against 10-20 pmol
l-1 for the surface water and the pore water. On the other hands high bacteria abundances
(108 cells l-1) were found in the coelenteric fluid. Thus the hypothesis that vitamin B12
required by the zooxanthella was acquired through a symbiotic relation with the
coelenteric bacteria was made. In order to confirm this hypothesis, the impact of an
enrichment of vitamin B12, the requirement of zooxanthella and the possibility of a
translocation of the vitamin between the bacteria and the zooxanthella were investigated.
The different results precised the integration of the coelenteric bacteria in a biochemical
symbiosis with corals and zooxanthella.
19-18
Terrestrial Organic Matter Contribution in Surface Sediment Of Northern Mid
Reef, Ishigaki Island, Japan
Yumi KOTAKE 1 , Yutaka TATEDA* 2
1 Tokyo College of Medico-Pharmaco Technology, Tokyo, Japan, 2 Environmental
Science Research Laboratory, CRIEPI, Abiko Chiba, Japan
To evaluate the origin of organic matter being sedimented in the fringing reef
environment, normal alkanes from C12 to C36 were analyzed in the reef surface sediments
to identified the origin of the end member of organic matter loading from adjacent
mangrove ecosystem. Marine biota originated C15,17-alkanes peaks were obvious in the
reef sediment, while the common signal of the terrestrial vegetation C31 alkane peak
were also detected, indicating some reef areas receive significant organic matter
loading from terrestrial organic matter especially of mangrove. The straight chain nalkanes
detected in reef surface sediments at Ishigaki northern mid reef area, Okinawa,
Japan were estimated to reflect the input of marine biota originated organic matter to be
39 -64 %, mangrove leaf originated organic matter to be 31 - 61 %, upstream riverside
soil originated organic matter to be 3 - 9 %. The result of field decomposition
experiment using terrestrial leaf indicated that turn over rates of terrestrial organic
matter in reef sediment environment were within a range of 3 - 12 months. The overall
result indicated that n-alkanes ratio of the end members: marine, mangrove, upstream soil
n-alkanes are regarded as a good fingerprints to estimate the contributions of organic
matter loading into the reef sediment, suggesting its usefulness for estimate how the
stability of coral reefs linked to the biogeochemical cycles keeping the health of coral
reef ecosystem, and also for the estimation of upstream land-derived soil loading to reef
area under future land use planning.
19-19
The Role Of Mucus Flocs in The Biogeochemical Cycle On Intertidal Coral Reef
Yu TAMURA* 1 , Makoto TSUCHIYA 2
1 Graduate school of Engineering and Science, University of the Ryukyus, Ginowan-shi
Okinawa-ken, Japan, 2 Faculty of Science, University of the Ryukyus, Naha-shi Okinawa-ken,
Japan
On intertidal reef flats, thin films consisting of fine sand, algae and detritus often form on the
water's surface during the flooding tide. When drifted by wind, these films develop into thick
mucus flocs (MF). MF are transfered by the flooding tide, and are either deposited to the
sediments after the gas bubbles inside it disappear, or are dispersed in the water. The organic
matter, lipid and carbon hydrate content were higher in MF than in surrounding sediments.
These substances seem to be produced by microorganisms like benthic diatoms that are
abundant in MF. Therefore, migration of MF may affect the spatial and temporal distribution of
nutrients in the oligotrophic coral reef environment.
The objectives of this study were to evaluate the contribution of MF as a food source for deposit
feeders and to assess the role of MF in the biogeochemical cycle within the coral reef. We show
that MF occur in sandy, exposed areas at the lagoon’s edge, and are then carried down wind to
the reef flat. The developmental process of MF were classified into 4 to 6 stages based on
observations. Then, weight per unit area of each stage was determined, and the occurrence areas
of each stage were measured to estimate total MF amount in one tidal cycle within the study
area. As MF were produced in larger quantities in July, the amount of nutrients supplied to the
reef flat from the lagoon’s edge may fluctuate depending on the season. In addition, to
investigate the contribution of MF as a food source for deposit feeders, we estimated the food
consumption of the Ophiocoma scolopendrina population, which is one of the most dominant
deposit and MF feeders in the intertidal.
19-20
Coral Mucus Creates A Short-Linked Energy And Nutrient Cycle Via Particle Trapping
in Fringing Reefs Of The Northern Red Sea
Florian MAYER* 1 , Andreas HAAS 1 , Malik NAUMANN 1 , Riyad MANASRAH 2 , Jonathan M
JESCHKE 3 , Christoph MAYR 4 , Christian WILD 1
1 Coral Reef Ecology Work Group (CORE), GeoBio-Center, Ludwig-Maximilians-Universität
München, München, Germany, 2 Marine Science Station, Yarmouk University, Jordan, Aqaba,
Jordan, 3 Dept. Biology II, Evolutionary Ecology, Ludwig-Maximilians-Universität München,
Martinsried-Planegg, Germany, 4 Department of Earth and Environment, GeoBio-Center,
Ludwig-Maximilians-Universität München, München, Germany
Mucoid exudates of hermatypic corals are known to play an essential role as energy carrier and
particle trap in reef ecosystems. The mucus trap mechanism prevents loss of essential elements
and facilitates fast recycling of organic matter within the oligotrophic system. Compared to
platform and atoll reefs where mucus is quickly detached from the coral due to strong tidal
currents, coral mucus produced in Red Sea fringing reefs remains significantly longer attached
to the coral. Therefore, the mucus trap mechanism is increasingly initiated on the coral surface.
Consequently, this suggests the existence of a short-linked nutrient cycle via coral-derived
organic matter in fringing reefs. We conducted a series of interconnected investigations during
two expeditions to the Northern Red Sea to understand the relevant processes underlying this
potential cycle. Highly contaminated mucus strings were attached to 14.6 % of all inspected
coral colonies (n= 733). Organic matter enrichment in mucus strings was determined by high
temporal resolution sampling. This revealed mean enrichment rates for particulate organic
carbon (POC) of up to 5.0 g h -1 L -1 of exuded mucus. After detachment from the coral, more
than 95 % of the highly contaminated mucus aggregates descended to the reef floor within a
distance of less than 5 m to the originating coral colony. In-situ and laboratory investigations
for planktonic and benthic microbial degradation of collected mucus aggregates showed high
organic C turnover rates. This confirms fast recycling of this material and a concomitant release
of regenerated nutrients essential for reef productivity. This study therefore indicates that shortlinked
nutrient cycles via coral mucus importantly contribute to reef ecosystem functioning in
the Red Sea.
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