11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 19: Biogeochemical Cycles in Coral Reef Environments
19.782
Exposure To Nutrient-Enriched Sediments Mitigates The Negative Impacts Of
Sedimentation On Coral Growth in The Caribbean Corals Porites Astreoides And
Siderastrea Siderea
Diego LIRMAN 1 , James HERLAN* 1 , Chis LANGDON 1 , Tom CAPO 1
1 Marine Biology and Fisheries, University of Miami, Miami, FL
Sedimentation is one of the main sources of disturbance to coral reefs worldwide.
However, the recent documentation of healthy coral communities in areas with high
sediment and nutrient inputs suggests that an enhanced heterotrophic environment may
allow corals to thrive under conditions often considered as marginal. In this study, we
document the effects of sedimentation on the growth of Porites astreoides and
Siderastrea siderea to evaluate whether the higher nutrient content of enriched sediments
can be utilized by corals to offset the negative impacts of sedimentation.
Both P. astreoides and S. siderea showed a high tolerance to chronic, high sedimentation
levels that reduced light levels and covered corals daily for three weeks. Limited tissue
losses were observed, but none of the coral fragments (2-3 cm in diameter) exhibited total
mortality. The growth of P. astreoides and P. siderea was significantly influenced by the
addition of sediments. For P. astreoides, control corals had the fastest growth rates,
followed by corals from the enriched nutrient treatment, non-enriched sediment
treatment, and finally, the shading treatment. No significant difference in growth rates
were documented between control corals and corals exposed to enriched sediments, but
these two groups grew significantly faster than shaded corals and corals exposed to nonenriched
sediments. For S. siderea, growth rates were highest for control corals, followed
by corals in the enriched sediments treatment, the shading treatment, and the nonenriched
sediment treatment. Significant differences were only documented between
controls and corals exposed to non-enriched sediments. The enhanced growth of Porites
astreoides and Siderastrea siderea exposed to nutrient-enriched sediments shows that
corals are able, at least in part, to offset the negative impacts of sedimentation by
assimilating sediment nutrients.
19.783
Clipperton Lagoon: A Possible Future For An Atoll Lagoon
Charpy LOIC* 1 , Rodier MARTINE 1
1 UR167, IRD, Marseille, France, Metropolitan
Clipperton Island, which is sometimes referred as Ile de la Passion (10°17’ N 109°13’ W)
is the unique coral atoll, in the eastern Pacific. During 2005, we participated to the Jean-
Louis Etienne expedition to investigate the lagoon and the surrounding oceanic waters of
Clipperton. Our results confirm the meromictic character of the deep basins due to the
last closure of the lagoon around 1849. We found a system with three layers of water
which did not intermix and the deepest layer did not contain any dissolved oxygen. The
transition layer between brackish and salted waters is characterized by a temperature
inversion of 1.6°C. The origin of this increase is probably due to the microbial activity.
Taking into account the methodological problems of previous measurements, the physical
characteristics of the lagoon do not seem to have changed significantly since the last
expeditions. The low DIN and SRP concentrations observed in the upper layer reflects
the important nutrient uptake by primary producers of the lagoon as attested by the
elevated gross primary production (3.8 g C m-2 day-1) estimated by O2 method.
Phytoplankton production integrated in the upper 3 m represents 21 % of the total
primary production (benthos + plankton). This comparison confirms the dominant role of
benthic plants (macrophytes or epiphytes) in lagoon global metabolism.
19.784
Variability Of Uvr Penetration And Its Biogeochemical Implications For Coral Reef
Ecosystems in Malaysia
Victor KUWAHARA* 1 , Taeko FURUKAWA 1 , Asami NAKAYAMA 2 , Ryota NAKAJIMA 2 ,
B. H. Ross OTHMAN 3 , Tatsuki TODA 2
1 Faculty of Education, Soka University, Tokyo, Japan, 2 Faculty of Engineering, Soka
University, Tokyo, Japan, 3 School of Environmental & Natural Resources Science, Universiti
Kebangsaan Malaysia, Bangi Selangor, Malaysia
Biologically diverse coral reef ecosystems, which are symbiotically dependent on
photosynthesizing zooxanthellae, are indirectly susceptible to small increases or changes to the
spectral UVR distribution. Prior studies have described that the photobiological effects of UVR
are largely determined by the underwater spectral UVR:PAR ratio that is directly controlled by
the absorption and scattering of biogeochemical material within the water column, i.e.
particulate organic matter (POM), dissolved organic matter (DOM), etc. The purpose of this
survey was to, 1) establish the current variability of UVR and PAR penetration above coral
reefs around the Malaysian peninsula, 2) measure the variability and distribution of UVR
specific biogeochemical factors and 3) determine the impact of biogeochemical variability as it
affects the UVR:PAR ratio. Downwelling UVR and PAR irradiance and bio-optically derived
biogeochemical factors were collected at 14 different coral biodiversity survey stations around
the entire Malaysian peninsula from August 10 – 29, 2007. The results show mean penetration
of the 1% surface UV-B radiation (320 nm) is generally deeper above reefs on the East coast
(16±7 m) relative to the West coast (5±3 m) around the Malaysian peninsula. The UVR:PAR
ratio was also generally higher on the East coast relative to the West coast reefs suggesting
variable concentrations of UVR-specific absorption. UVR attenuation at all biodiversity stations
showed significant relationships (P