11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 25: Predicting Reef Futures in the Context of Climate Change
25.1133
Rising Sea Level and Increased Turbidity on Fringing Coral Reefs
Michael FIELD* 1 , Andrea OGSTON 2 , Ann GIBBS 1
1 Pacific Science Center, U.S. Geological Survey, Santa Cruz, CA, 2 School of
Oceanography, University of Washington, Seattle, WA
Relative sea level is predicted to rise 2.2 to 4.4 mm/y and perhaps more this century. We
hypothesize that even small increases in sea level will increase wave energy on adjacent
reef flats and shorelines. This in turn will significantly increase turbidity on some coral
reefs by increased resuspension of sediment in shallow reef areas, and increased erosion
of fine sediment from adjacent coastal plains and deltaic deposits.
Sedimentation and suspended sediment are leading contributors to reef degradation, and
our studies in Hawaii indicate that sea-level rise has a strong potential to increase
suspended sediment concentrations (turbidity) on fringing coral reefs through increases in
both wave resuspension and wave erosion. Results from a well-studied fringing reef flat
(Molokai, HI) show that sediment is resuspended daily, and levels of suspended sediment
concentrations are primarily related to wind velocity, resulting waves, and water depth
(tide stage). Both the duration and magnitude of suspension events may increase with
even small increases in sea level over fringing reefs due to enhanced bottom stresses.
Given a rise of 10 cm in the next couple of decades, wave bottom stresses will be higher
and critical water depths will be reached earlier during rising tides and be maintained
longer during falling tides, resulting in longer and more intense turbidity conditions.
Increases in water depth of even 10 cm over reef crests may also increase wave energy on
adjacent shorelines, many of which are only thin sandy veneers capping older deposits of
alluvium. Waves at higher water levels within the tidal cycle have increased capability to
erode friable, unprotected deposits in low-lying areas over prolonged time periods. The
fine-sediment component of these deposits is susceptible to advection seaward and
deposition on the reef, potentially increasing the levels of suspended sediment.
25.1134
Coral Protection Under The U.s. Endangered Species Act
Miyoko SAKASHITA* 1 , Brendan CUMMINGS* 2 , Andrea TREECE* 1 , Shaye
WOLF* 1
1 Center for Biological Diversity, San Francisco, CA, 2 Center for Biological Diversity,
Joshua Tree, CA
Two coral species, elkhorn coral (Acropora palmata) and staghorn coral (A. cervicornis),
were recently protected as “threatened” under the United States Endangered Species Act
(ESA). Once the primary reef-building corals of Florida and the Caribbean, these species
have suffered an 80-98% decline in just 30 years. These corals face significant threats
from changing environmental conditions because of human-induced global warming and
pollution. In 2008, “critical habitat” will be designated for elkhorn and staghorn corals, as
required by the ESA. Using the case study of the corals, we examine the protections that
the ESA provides, including the listing process, critical habitat designation, and recovery
planning. We discuss how the ESA’s statutory prohibitions against “jeopardy” and
“adverse modification” of critical habitat for listed species might apply to greenhousegas-generating
actions of U.S. federal agencies. The ESA remains highly relevant to
species preservation in a changing climate, providing mechanisms to address both
mitigation (reducing greenhouse gas emissions) and adaptation (ecosystem management).
25.1135
Species Specific Responses To Experimental Bleaching Of Corals
Deborah VIVIAN* 1 , Susan YEE 1 , Sarah KELL 1 , Cheryl MCGILL 1 , Mace BARRON 1
1 Gulf Ecology Division, US EPA, Gulf Breeze, FL
The combined effects of temperature and solar radiation on six species of reef-building corals
were examined using a laboratory coral exposure system. Diploria clivosa, Montastraea
faveolata, Siderastrea siderea, Siderastrea radians, Stephanocoenia intersepts, and Porites
astreoides were first exposed for 10 days to two temperatures (26 or 31oC) and three solar
radiation doses (ultraviolet radiation (UVA) at 13.7, 68, and 84 W•d/m2). Corals were then
monitored for a 40 day recovery period. A pulse amplitude modulation (PAM) fluorometer was
used to monitor changes in photosystem II efficiency (∆Fv/Fm) during the exposure period.
Weekly observations and PAM measurements were conducted during the recovery period to
assess changes in bleaching and health. After recovery, pigment, zooxanthellae, and protein
concentrations were analyzed to determine recovery rates of corals. During initial exposure,
species responded differently to the combined effects of temperature and solar radiation with P.
astreoides showing the greatest decline in Fv/Fm over time and S. siderea showing the least
change in Fv/Fm. Most species responded similarly to temperature showing a decrease in
Fv/Fm in the 31oC treatments. However, species response to light was significantly different (p
= 0.038), with S. intersepts showing the greatest response to high radiation and S. siderea the
weakest. Highest mortalities were observed in S. intersepts and M. faveolata (22%) exposed to
the highest solar radiation at the end of exposure. Changes in Fv/Fm showed poor recovery for
only S. intersepts and M. faveolata exposed to high solar radiation. Recovery rates based on
pigment, zooxanthellae, and protein concentrations were variable among species and treatments.
Responses to combined effects of solar radiation and temperature are species specific for both
experimental bleaching and recovery.
25.1136
Making The Loss Of Coral Reefs A Personal Matter
John WARE* 1
1 SeaServices, Inc., Gaithersburg, MD
The primary objective of this study is to focus attention on coral-reef problems at the individual
level in order to increase public awareness and involvement with climate change issues. A
secondary objective is to demonstrate the utility of a simplified “reefs-in-the-greenhouse”
model for predicting the effects of climate change on coral reefs.
The unique feature of this study is that it relates reef loss and survival on a per capita basis so
that these issues become a personal matter. The abstract allegation: “Coral reefs are dying and
that CO2 emissions are a major cause”, does not allow the average person to relate his/her
actions to real-world effects. My alternative conceptualization: “Reducing your future CO2
emissions can save N m 2 of coral reefs” permits individuals to assess how their activities relate
to the very real threats to reefs.
CO2 emissions are used as a surrogate for all the ills that humanity has imposed on coral reefs
because, in addition to direct temperature and acidification effects, CO2 emissions correlate
with many other negative impacts on reefs. That is, people who emit large quantities of CO2
also tend to be indirectly responsible for other reef problems (e.g., overfishing, pollution, and
sediment loading).
Focusing on the United States, but with global implications, I couple a simplified model of
climate change with a unique simultaneous simulation of more than 1000 reef types to draw
conclusions with regard to reef survivability under various CO2 emissions scenarios. The reef
types cover a broad spectrum of temperature environments, bleaching/mortality thresholds,
resilience/recovery, and adaptation potentials. The model has been calibrated using observed
warming and present reef status.
Although the future of reefs is not bright, reducing future warming coupled with coral
adaptation potential, even on the scale of 100 years, can result in reef survival.
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