11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 19: Biogeochemical Cycles in Coral Reef Environments
19.794
Seasonal Variation Of δ 15 n in Coral Skeletons
Atsuko YAMAZAKI* 1 , Tsuyoshi WATANABE 1 , Tatsunori KAWASHIMA 1 , Naohiko
OHKOUCHI 2 , Nanako OGAWA 2 , Mitsuo UEMATSU 3
1 Graduate School of Science, Hokkaido Univercity, Sapporo, Japan, 2 Institute for
Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology,
Yokosuka, Japan, 3 Ocean Research Institute, The University of Tokyo, Tokyo, Japan
The skeletons of scleractinian corals are composed of aragonitic skeletons and a few
amount of organic matrix containing nitrogen. In this study, we estimated the origin of
δ 15 N changes in coral skeletons and demonstrate the possibility that coral δ 15 N could be a
powerful tool of reconstructing paleoenvironments.
We collected two corals from the mouth of Todoroki River in Ishigaki Island, and
Okinotori Island, Japan. Ishigaki coral had grown under strong influence of terrestrial
input such as the fertilizer from cane fields thorough the Todoroki River. In contrast,
Okinotori Island is isolated in open ocean and very apart from any terrestrial sources (900
km). Typhoons come across Okinotori Island very frequently and cause upwelling which
brings nutrient rich water from deeper layer. We analyzed their δ18O and δ13C with 200
μm intervals using Finnigan Mat 251 in Hokkaido University, and δ15N with 800 μm
intervals using Finnigan Delta plus XP in JAMSTEC, respectively.
The average δ15N and total nitrogen (TN) of Ishigaki coral are 1.5 ‰ and 0.01% larger
than those of Okinotori coral, respectively. This is probably due to the difference of
nutrient sources. Furthermore, constant nutrient supply in Ishigaki Island, bring enough
primary production to coral reef. Consequently, δ15N is different between two sites. δ 15 N
in Okinotori coral correlates with TN. δ 15 N and TN have positive peaks in low SST
season, when vertical mixing brings nutrients to sea surface. These positive peaks are
also found after typhoon events. A supply of nutrients promotes activity of zooxanthellae,
which makes δ 15 N in coral large.
The results suggest that δ 15 N in coral could record the changes of symbiotic algae activity
and it can be expected to use as a new marker for reconstructing past environmental and
physiological changes.
19.795
Evaluation Of Stable Isotope Analysis As A Tool For Monitoring Impacts Of
Anthropogenic Nutrient Inputs On Coral Reefs
James FOLEY* 1
1 School of Marine Science & Technology, Newcastle University, Newcastle, United
Kingdom
Sewage can have severe implications for animal trophodynamics over coral reefs. Tobago
reef algae have previously been identified as sewage impacted with impacts reducing
with distance from source. Here the impact is assessed of sewage from two known point
source sewage outfalls on Tobago’s coral reefs over multiple trophic levels to assess the
degree to which these impacts extend up the reef food chain. Stable isotope analysis
(SIA) measured spatial and trophic variation of nitrogen and carbon stable isotope ratios
(δ 15 N and δ 13 C) in tissues from four coral reef organisms at different trophic levels, and
from particulate organic matter (POM) from two sewage/domestic waste outfalls.
Organisms progressively distant from effluent outfalls showed no significant differences
in δ 15 N or δ 13 C between sites, apart from at the highest trophic level. δ 15 N and δ 13 C of
POM from one outfall were similar to δ 15 N and δ 13 C of estimated natural marine primary
production sources, although POM from a second outfall differed from this. However,
discharge from the second was too low at this time of year to reach the sea, rendering it
unable to contribute to coral reef production sources. Data correlates with another study,
showed significant temporal variability in primary production sources. Together, these
data indicate either no significant effect of anthropogenic nutrients from these two point
sources on Tobago’s coral reefs during the dry season, or that SIA is unable to detect
effects due to sewage signals not differing from signals of natural production sources e.g.
phytoplankton. With increasing use of SIA in ecological studies, this demonstrates
importance of appropriate use of monitoring tools, improved understanding of
limitations, and caution in their use to avoid misinterpretation and consequent
expenditure on ineffective mitigation strategies.
19.796
Diel Patterns of Abundance and Vertical Distribution of Zooplankton over a Florida
Coral Reef
Keri O'NEIL* 1 , Karla HEIDELBERG 2 , Kenneth SEBENS 3
1 National Aquarium in Baltimore, Baltimore, MD, 2 Department of Biological Sciences and
Wrigley Institute of Marine Science, University of Southern California, Avalon, CA, 3 Friday
Harbor Laboratories and Department of Biology, University of Washington, Friday Harbor,
WA
Zooplankton on corals reefs comprise reef resident species, demersal migrating species, open
ocean holoplankton advected onto reefs, and meroplankton from both open ocean and reef
sources. This diverse zooplankton resource provides substantial nutrient input to the reef
ecosystem via reef fish, corals and other predators. We examined vertical and temporal patterns
of zooplankton associated with Conch Reef in the Florida Keys. Intensive diel sampling was
accomplished via saturation diving (Aquarius underwater laboratory), allowing samples to be
collected both at the surface and at depth six times daily for seven consecutive days. Samples
were pumped at four heights above the substrate, including just above coral tentacles. Oithona
spp. were the most abundant copepods and this species was evenly distributed with depth.
Acartia spp. comprised the second most abundant copepod genus and had significant
differences with both time and depth. Several taxa were homogeneous throughout the water
column, while others were generally more surface or substrate associated. The behavior of
certain holoplankton associating with reefs may explain some of the patterns found here. This
spatially and temporally stratified sampling regime allows an accurate description of
zooplankton taxa available as prey for benthic suspension feeders, such as anemones and corals,
and for fish and other zooplanktivores on and at discrete heights above reef surfaces.
19.797
Physiological Effects Of Submarine Groundwater Discharge On The Hawaiian Marine
Alga gracilaria Coronopifolia
Daniel AMATO* 1
1 Botany, University of Hawaii Manoa, Honolulu, HI
Submarine groundwater discharge (SGD) is thought to be a significant source of nutrients to
many coastal ecosystems. To date, a causal relationship between SGD and primary
productivity has not been described. In order to determine the physiological effects of this
process on coastal macroalgae, the Hawaiian endemic edible red alga Gracilaria coronopifolia
J. Agardh was collected and grown in a highly controlled flow-through digital mesocosm. To
simulate increasing levels of SGD, treatments ranged from an ambient oceanic control of high
salinity/low nutrients to low salinity/high nutrients. Empirical relationships among salinity,
nitrate, and phosphate from known sites of SGD in Hawaii were used to determine the chemical
composition of four treatments with six replicates per treatment. After 16 days, the mean
specific growth rate and apical tip development of the 27‰ salinity treatment was at least two
times greater than controls (p=0.003, p=0.000). The 11‰ salinity treatment was found to be
close to G. coronopifolia's subsistence threshold. Pulse amplitude modulated chlorophyll
fluorometry (PAM), in vivo pigment absorbance, and chlorophyll a measurements indicate the
photosynthetic efficiency of treatments 19‰, 27‰ and 35‰ is not significantly different. The
results of this study demonstrate that water chemistry parameters which simulate moderate
amounts of SGD in a tropical oligotrophic environment more than double the growth rate and
development of new apical tips in G. coronopifolia when compared to ambient oceanic
controls. This conclusion has important implications for management of native and invasive
species, coastal primary productivity, and groundwater conservation. The parameters “Tip
Score” and “New Tip Index” developed during this study are novel and effective techniques for
the quantification of algal apical tip development.
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