11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 4: Coral Reef Organisms as Recorders of Local and Global Environmental Change
4.63
Coral Morphology As An Indicator of Sedimentation Rate; Cañada Honda,
Dominican Republic
Allicia DAVIS* 1 , Dennis HUBBARD 2
1 Dept. of Geological Sciences, Indiana University, Bloomington, IN, 2 Geology Dept.,
Oberlin College, Oberlin, OH
Coral distribution, abundance, and morphology were measured in a subaerially exposed
Holocene coral reef in Cañada Honda, which is located in the western Dominican
Republic. Four coral facies (branching, mixed, and two distinct massive-coral beds) have
been identified. The lowermost massive-coral facies is focused on for this study. The
facies is divided into two beds, by a probable storm layer. Six vertical transects were
done throughout the two beds with sampling occurring at 20-cm intervals. Twenty corals
at each transect were described in terms of morphology, degree of bioerosion, and
vertical position within a facies. Samples of typical corals were collected for lab
analyses.
The lower bed of the facies, M1, is distinguished by the prominence of Montastrea spp.,
while Siderastrea spp. dominates M2, the higher bed. Differences in colony morphology
also distinguish the facies: M1 has more corals with ‘pancake’ morphologies (i.e. draping
of successive layers) while M2 shows a more diverse range of shapes, including domes,
inverted cones, and ‘pancakes.’ All shapes can be associated with multiple coral species,
but Montastrea spp. strongly tends toward the ‘pancake’ morphology.
The excellent exposure at Cañada Honda allows for the correlation of growth form with
sedimentation rate and degree of bioerosion. Overall, conical forms tend to be more
bioeroded, regardless of species or facies. Therefore, they either grew faster or
encountered slower sedimentation, resulting in colonies with longer exposure times and
more bioerosion. High and variable sedimentation rates lead to periodic swamping of
pancake-shaped colonies, which then overgrew the sediment as deposition slowed. Rapid
burial led to less bioerosion. Annual growth bands revealed in X-radiographs can be
used to quantify this relationship. Comparison of coral growth-rates in various forms
may allow for the assignation of absolute values to terms such as “fast” or “slow” with
respect to sedimentation in fossil reefs.
4.64
Reconstruction Of Climatic Variability Induced By The Pna Pattern in The
Southern Gulf Of Mexico: Geochemical Evidences From Coral Growth Bands
Constanza RICAURTE* 1 , Jose CARRIQUIRY 1 , Julio VILLAESCUSA 1 , Guillermo
HORTA 2
1 Instituto de Investigaciones Oceanologicas, Universidad Autonoma de Baja California,
Ensenada, Mexico, 2 Facultad de Estudios Superiores Iztacala, Universidad Autónoma de
México, Mexico D.F., Mexico
The climatic conditions of the Gulf of Mexico region are strongly influenced by largescale
extra-tropical variability in the atmospheric circulation of, well-known as Pattern
Pacífic/North american (PNA) (Slowey and Crowley, 1995). Although coral records have
been extensively used to study tropical climatic events as El Niño and the South
Oscillation, little has been made to understand the influence of extra-tropical phenomena
like PNA on the tropical regions, such as the southern Gulf of Mexico. In this work we
show that the rate of skeletal growth and the calcification rate of the coral Montastraea
faveolata, collected from the Veracruz Reef System, in Mexico, is influenced by the
effects of the PNA, which in turn affects sea surface temperature (which was
reconstructed from Sr/Ca and Mg/Ca ratios). The rate of skeletal growth (cm year-1) of
the coral Montastrea faveolata increases during the positive phase of the PNA pattern (in
winter), characterized by negative anomalies in SST, while the rate of calcification (gr
cm-2 year-1) increased during the negative phase of the PNA pattern (in summer) which
is characterized by positive anomalies of SST. This means that the corals’ annual growth
respond to longer-term (decadal?), extreme variability of SST. The close relationship
between the coral growth rate and calcification rate with PNA variability, suggest that
corals are not only responding to SST changes, but to broader climatic conditions
resulting from atmospheric climate patterns developing in the region. These results also
indicate that it is possible to reconstruct the historical variability of the PNA in timescales
that exceed those available from instrumental records.
4.65
Enso Variability Recorded in The Growth Rate Of Southwestern-South Atlantic Corals
Danielly GODIVA* 1 , Heitor EVANGELISTA 2 , Abdelfettah SIFEDDINE 3 , Zelinda LEÃO 4 ,
Nivaor RIGOZO 5 , Barbara SEGAL 6 , Tércio AMBRIZZI 7 , Milton KAMPEL 8 , Ruy KIKUCHI 4
1 Geoquímica Ambiental, Universidade Federal Fluminense, Rio de Janeiro, Brazil,
2 Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil, 3 Institut de Recherche pour
le Développement, Paris, France, 4 Universidade Federal da Bahia, Salvador, Brazil, 5 FAETEC,
São José dos Campos, Brazil, 6 Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de
Janeiro, Brazil, 7 Universidade de São Paulo, São Paulo, Brazil, 8 Instituto Nacional de Pesquisas
Espaciais, São José dos Campos, Brazil
The knowledge of the effects produced by El Niño Southern Oscillation (ENSO) to marine
communities from the Southwestern-South Atlantic (SWSA) is restricted to observations from
recent years. To extend these observations back in time, we conducted a study of coral skeleton
from the Abrolhos Coral Reef Bank (ACRB), Brazil, and compared them to meteorological and
oceanographic parameters in order to better understand the impact of ENSO during past
decades. Here, we present an evidence of potential El Niño impacts in the SWSA inferred from
the sclerochronology of the massive coral Favia leptophylla. The application of spectral
analysis (wavelet decomposition and the iterative regression) to coral growth length and to
meteorological-oceanographic parameters (air temperature, sea surface temperature and
precipitation) as well as to the Southern Oscillation Index (SOI) and solar irradiation indicated a
major significant inverse relationship between SOI and coral growth length in the 4–8 years
frequency band. We propose that coral growth rate in the SWSA could be affected by El Niño
Southern Oscillation (ENSO) events through an ‘‘atmospheric bridge’’. Although more work is
needed to better define the relationship between coral growth rate and the SOI, we found that
during El Niño years, southerly cold fronts do not reach the ACRB, reducing the water turbidity
and favoring coral growth.
4.66
Sclerochronology And Geochemistry Of Brazilian Corals To Reconstruct Southwestern-
South Atlantic Climate Variability
Danielly GODIVA* 1 , Heitor EVANGELISTA 2 , Abdelfettah SIFEDDINE 3 , Bruno TURCQ 3 ,
Thierry CORRÈGE 4 , Nivaor RIGOZO 5 , Ruy KIKUCHI 6 , Zelinda LEÃO 6 , Milton KAMPEL 7 ,
Renato CAMPELLO 8
1 Geoquímica Ambiental, Universidade Federal Fluminense, Rio de Janeiro, Brazil,
2 Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil, 3 Institut de Recherche pour
le Développement, Paris, France, 4 Université Bordeaux 1, Talence, France, 5 FAETEC, São José
dos Campos, Brazil, 6 Universidade Federal da Bahia, Salvador, Brazil, 7 Instituto Nacional de
Pesquisas Espaciais, São José dos Campos, Brazil, 8 Geoquímica Ambiental, Universidade
Federal Fluminense, Niterói, Brazil
It has been shown that interannual variations of environmental parameters (e.g. sea surface
temperature (SST), salinity, P/E balance and sediment supply) are recorded in the high and low
density growth bands of coral skeleton. Here, we investigate the potential of Siderastrea stellata
and Favia leptophylla, Southwestern-South Atlantic (SWSA) zooxanthellate corals, as archives
of physical and biological changes in the marine environment, induced by oceanic-atmospheric
processes. The coral samples were obtained from different Brazilian coastal sites exposed to
different environmental and anthropogenic forcing factors. The SST and salinity will be studied
through the geochemical composition (stable oxygen, Sr, Ba, Mg, Ca) of coral skeletons.
Preliminary sclerochronology studies from X-ray radiographs on corals from Buzios (22º 44’ S
41º 88’ W - 22º 75’ S 41º 53’ W) and Abrolhos (17º 52’ S 39º 14’ W - 18º 01’ S 38º 66’ W)
showed a different growth pattern between the two sites. The Abrolhos corals growth present a
linear decrease for the past 35 years whereas the Buzios corals seem to have a more stable
growth rate despite the fact that they grow in shallower waters and are sometimes exposed
during low tides. The Morlet wavelet decomposition and the iterative regression applied to
SWSA coral growth band length and to climatic parameters (SST, air temperature, precipitation,
Southern Oscillation Index and solar irradiation) indicate growth cyclicities around 2-3 years, 4-
7 years, and a decadal component that seem to correlate with the physical parameters. A more
precise sclerochronology study using a digital X-ray apparatus will be conducted, as well as
geochemical analyses on specific transects.
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