11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 3: Calcification and Coral Reefs - Past and Future
3.33
Coral Growth Of Porites Astreoides Correlates Negatively With Temperature
Along The Coast Of Venezuela
Marco CAPUTO* 1 , Carolina BASTIDAS 1 , Elia GARCÍA 1 , Sebastian RODRÍGUEZ 1
1 Laboratorio de Comunidades Marinas y Ecotoxicología, University Simon Bolivar,
Caracas, Venezuela
Coral growth correlates positively with sea temperature in most cases and it relates to the
coral species and the environmental conditions in a complex way. In this study we
measured the growth of Porites astreoides as the maximum lineal extension of carbonate
accretion, using computer tomography to reveal the pattern of density bands. A nested
design was used to assess the variability of coral growth at scale of meters, kilometers
and hundred of kilometers, the largest scale corresponding to localities at the Morrocoy
National Park, and the islands of La Blanquilla and Cubagua. These localities differed up
to 6.1 C ° in their monthly mean Sea Surface Temperature (10 years of record), among
other environmental conditions. We found a yearly growth of 5.85 ± 1.92 mm, 3.65 ±
1.32 mm and 2.84 ± 1.27 mm for the colonies of Cubagua, La Blanquilla and Morrocoy,
respectively. Surprisingly, these rates of growth correlated negatively with the mean SST
of those localities. We also found significant differences in the rate of growth of Porites
astreoides at the scale of meters, but not at the intermediate scale of kilometers. The
effect of temperature on coral growth as found in this study, indicates that at some
localities an elevation in SST in the future could negatively affect coral lineal extension.
3.34
Rising Co2 Disproportionately Affects Extension Versus Mass Deposition in Reef
Corals
Nancy MUEHLLEHNER* 1 , Peter EDMUNDS 1
1 Biology, California State University, Northridge, Northridge, CA
The production of mineral skeletons by scleractinian corals is one of the primary sources
of topographical complexity on tropical coral reefs. Although ocean acidification is
known to decrease calcification in corals, the effects have been measured almost
exclusively in terms of the mass deposition of aragonite. Interestingly, it remains
virtually unknown how this translates into morphological consequences in a taxon well
known for phenotypic plasticity. This study used manipulative experiments to test the
hypothesis that increasing pCO2 has unequal effects on different components of growth
that contribute to colony size and morphology. First, increased levels of CO2 (700 vs.
350 µatm) were tested for effects on the mass deposition (µg mm-2 day-1) and linear
extension (µm day-1) of Acropora hyacinthus and A. pulchra in French Polynesia. The
experiments were completed using microcosms exposed to light levels of ~650 µmol m-2
s-1, ambient temperature (28˚C) and a pH treatment of 7.8 or 8.2. Overall, mass
deposition and linear extension were significantly reduced by high pCO2 in both species.
For A. pulchra, high CO2 reduced mass deposition by 26%, from 4.9 + 0.1 to 3.7 + 0.2
µg mm-2 d-1, and linear extension by 44%, from 245 + 15 µm d-1 to 137 + 11 µm d-1
(all mean + se). In A. hyacinthus, the disproportional effects of high CO2 on mass
deposition and extension were accentuated, with mass deposition reduced 25%, from 3.0
+ 0.7 to 2.2 + 0.5 µg mm-2 d-1, and linear extension by 146%, from 3.0 + 5.0 µm d-1 to -
1.38 + 2 µm d-1 (all mean + se). Importantly, in both cases, high CO2 had a significantly
greater effect on linear extension than on mass deposition, with extension reduced 2-6
fold more than mass deposition.
3.35
Carbonate production on coral reefs – the influence of terrestrial runoff on encrusting
communities and coral recruits
Jennie MALLELA* 1
1 Life Sciences, University of the West Indies, Trinidad, Trinidad and Tobago
Land based runoff (e.g. sediment and nutrients) is now recognised as a serious threat to coral
reef development in the Caribbean. This study assessed whether reefal carbonate production by
encrusting organisms (crustose coralline algae, bryozoans and foraminifera) and coral recruits
was influenced by terrestrial runoff (e.g. fluvial inputs). Experimental substrates were deployed
at ten marine sites along a gradient of terrestrial disturbance in Jamaica (n=4) and Tobago
(n=6). Artificial substrates were deployed in order to mimic cryptic and exposed reef substrates
(downwards-facing versus upwards-facing). Initial findings indicate that encruster carbonate
production (g m-2 y-1) was significantly higher at less terrestrially impacted sites, characterised
by high wave energy, than that observed at sites subjected to high levels of terrestrial runoff and
low wave energy. Cryptically orientated tiles were also found to support a greater diversity of
encrusting organisms. Comparisons in Jamaica with earlier (1970s) studies indicate that
encruster cover on the reefs has reduced. Findings from this study have implications for both
current and future rates and styles of reefal framework production.
3.36
Mineral phase of COCs and fibers in coral skeletons
Kohki SOWA* 1 , Tsuyoshi WATANABE 1 , Satoko MOTAI 1 , Yusuke SETO 1 , Takaya NAGAI 1
1 Hokkaido university, Sapporo, Japan
It should be useful to get mineral phase information corresponding to coral skeletal textures
from micro- to nano-meter scale (microstructure and nano-texture are used as terms,
respectively). To confirm mineral phase differences in coral skeletons, we conducted mineral
phase identification in microstructures and nano-textures on coral, Porites lobata.,by X-ray
diffraction analysis with synchrotron radiation (SR-XRD) and transmission electron microscope
(TEM) respectively. Coral microstructures consist of center of calcifications (COCs) and fibers.
COCs occupy small volume percentage (~3%) against the total volume of coral skeletons. The
size of COC is