Coral Reef Activities -- U.S. National Science Foundation
prtaylor at nsf.gov
prtaylor at nsf.gov
Fri Mar 8 10:19:17 EST 1996
To anyone interested:
The attach file outlines many research and related projects that were
supported by the U. S. National Science Foundation in Fiscal Year 1995
as part of the U. S.Coral Reef Initiative and its contribution to the
International Coral Reef Initiative.
Phil Taylor
Division of Ocean Sciences
U. S. National Science Foundation
4201 Wilson Blvd.
Arlington, Virginia 22230 USA
prtaylor at nsf.gov
703-306-1587
To anyone interested:
The attach file outlines many research and related projects that were supported by the U. S. National Science
Foundation in Fiscal Year 1995 as part of the U. S.Coral Reef Initiative and its contribution to the International Coral
Reef Initiative.
Phil Taylor
Division of Ocean Sciences
U. S. National Science Foundation
4201 Wilson Blvd.
Arlington, Virginia 22230 USA
prtaylor at nsf.gov
703-306-1587
3/8/96
**********************************************
Population Biology of Caribbean Octocorals
Daniel Brazeau, University of Florida
Fertilization success among sessile, marine invertebrates is a largely unknown variable bridging those factors which
field ecologists can measure (fecundity, organism size, population abundance) and one often difficult to estimate
(reproductive success). Using the Caribbean octocoral Baiareum asbestinum as a model animal, this project will
examine temporal and spatial variation in reproductive success for male and female colonies. The research will test
the specific prediction that female fertilization success is directly proportional to the nearby abundance male colonies.
This information is crucial for understanding the abundance and growth of invertebrate populations in coral reef
ecosystems and will provide important information for the successful restoration and management of coral reefs
worldwide.
The Role of Heterotrophic Dinoflagellates in Marine Plankton Dynamics: Growth, Grazing Behavior and
Bioluminescence
Edward Buskey, University of Texas Austin
This study will examine the effects of food quantity and quality on the growth, feeding and bioluminescence of
several species of Protoperidinium. Selective feeding of these pallium, feeding dinoflagellates (which capture large
food particles extracellualarly) and the role of sensory perception in this selection process will also be examined. In
addition, the study will determine the abundance of heterotrophic dinoflagellates in the western Gulf of Mexico, and
examine the relationship between growth rate and bioluminescence capacity for field collected Protoperidinium
incubated at ambient food concentrations.
Hydrodynamic Forcing of Metabolism of Coral Reef Algal Communities
Robert Carpenter, California State University Northridge
and
Susan Williams, San Diego State University
The current paradigm explaining how coral reefs maintain high biomass of organisms and extremely high rates of
gross primary productivity is that tight recycling of nutrients and organic matter occurs within the reef resulting in
zones of net autotrophy alternating with zones of net heterotrophy. Autotrophic upstream communities are thought to
support downstream heterotrophic assemblages with the overall balance resulting in ecosystem P/R ratios near unity.
According to this paradigm, coral reefs are not coupled significantly to the surrounding oligotrophic ocean. Recent
studies suggest that coral reefs may be much more dependent on hydrodynamic processes than currently believed.
Although nutrient concentrations of tropical waters are very low, an enormous volume of water is advected across the
reef and could result in a large flux of nutrients to benthic primary producers. The major upstream autotrophic zone is
the reef flat where algal turf assemblages are responsible for the majority of primary productivi
ty. Previous work has demonstrated that rates of primary productivity and nitrogen fixation of algal turf are affected
significantly by water flow speed. Furthermore, flow measurements on one reef suggest that algal canopy height
significantly alters the local hydrodynamic regime and as a result, metabolic processes of algal turfs may be diffusion-
limited for a significant proportion of time. This project will test the hypothesis that rates of primary productivity and
nitrogen fixation of coral reef algal turfs are diffusion-limited. Measurements of the flow environment on a reef flat
will be made and used to estimate the degree to which algal turfs varying in canopy height are diffusion-limited. The
project will then move on to test hypotheses about the specific factors that result in diffusion- limitation. The results
of this project should fill a gap on empirical measurements of water flow in coral reef environments and how water
flow affects algal metabolism. The results of this research may lead to a si
gnificant paradigm shift in understanding how coral reefs function. Demonstration that reefs are open ecosystems that
are strongly coupled to the surrounding ocean environment would have important implications for predictions of the
effects of global climate change on these unique ecosystems.
Population and Community Dynamics of Corals: A Long Term Study.
Joseph Connell, University of California, Santa Barbara
The objectives of the present project are several: 1) To extend the detailed long-term monitoring of ecological
communities of corals and algae on the Great Barrier Reef, Australia which has been carried on continuously over the
past 30 years, the longest such study on any coral reef; 2) to expand the study to include sites on two nearby reefs,
and additional replicate sites on Heron Reef; 3) to analyze spatial patterns and dynamics of corals and algae at several
scales, from centimeters to tens of meters, both during the course of colonization of patches (opened by disturbances)
and after most of the surface has become crowded by many colonies. These analyses should reveal the long-term
effects of interactions that may be crucial in determining how natural communities are structured; 4) to test with
controlled field experiments some hypotheses about mechanisms: a) that produce the unique species composition of
corals at the Inner Reef Flat site, b) that cause contrasting patterns of algae after disturbances
, and c) that determine precisely how each colony affects its neighbors; 5) to build mathematical models and computer
simulations of the dynamics of these populations and communities of corals and algae: a) to investigate the influence
of past and present conditions on future changes, b) to characterize temporal and spatial dynamics, and c) to test
hypotheses about the consequences of these dynamics to the community. The models will be also used to asses the
degree to which community structure and dynamics may or may not be influenced by details of spatial relationships.
The field methods will use the standard sampling techniques used over the past 30 years, to assure continuity in the
long-term data base. The experimental methods, using coral transplanting and cages to exclude larger herbivores,
have also been used before in this study and are well- established. Larval choice experiments and new recruit
transplants have been carried out successfully by the co- investigators elsewhere on the Great Barrier Re
ef.. The significance of this proposed research to the advancement of knowledge is that: 1) it deepens the general
knowledge of how natural communities of corals and algae (the dominant sessile organisms on tropical and sub-
tropical reefs), are assembled and structured in the face of changes in their environment over extended periods of
time; 2) it reveals some of the mechanisms that link the environment with these community changes, and how both
vary over short and long time periods and between small and larger spatial scales; and 3) it helps to predict the effect
of environmental changes, including those caused by human activity, on these natural communities.
Grazer Diversity and Ecosystem Function in Seagrass Beds
J. Emmett Duffy, College of William & Mary, Virginia Institute of Marine Science
One of most pervasive and irreversible effects of environmental change wrought by human activity is the reduction in
species diversity on local and global scales. The consequences of declining for ecosystem function remain largely
unquantified and unpredictable. The loss of species in low diversity but high recruitment environments, like
estuaries, may severely alter production levels and trophic transfers. This research will involve a series of mesocosm
experiments to test the effects of invertebrate grazer species on: 1) the structure of eelgrass communities, particularly
the algal epiphytes, 2) functional processes within the eelgrass ecosystem, especially primary and secondary
production, vascular detritus processing, and organic matter export to underlying sediment, and 3) the responses of
the plants to nutrient enrichment. The results of this work are likely to provide the first experimental evidence about
the roles of mesograzers in shallow water vegetation communities, including their individual and
collective effects on community structure and function.
Ribosomal DNA Sequences in Marine Yeasts: A Model for Identification and Quantification of Marine Eukaryotes
Jack Fell, University of Miami, Rosensteil School of Marine & Atmospheric Sciences
Using molecular techniques for rapid and accurate determination of community structure, this research will determine
fungal biodiversity and population biomass in tropical caostal ecosystems (principally mangrove ecosystems) of two
distinctly different groups of micro-fungi: the basidiomycetous yeasts and the oomycetous genus Halophythophora.
Both groups have important roles in detrital based food webs. The research program will include laboratory and field
studies. Laboratory studies will complete the data bank of know species as a basis for determining community
structure in the field. New procedures will be developed with preliminary emphasis on quantitative PCR (QPCR)
using laser detected infrared labeled primers. Field research will center on reef and mangrove habitats. Using a
combination of classical microbial techniques and molecular methods, the community structure and relative
abundance of known and unknown culturable fungi species will be determined. The identity of these species will be
ascertain
ed by automated DNA sequence analysis and nucleotide alignment with the data bank. Species-specific regions will
be located and primers developed to test the accuracy and sensitivity of PCR techniques in estimating community
structure. Through the use of PCR and QPCR, the occurrence of unculturable species and population densities will be
estimated. The techniques developed in this research can be applied to population analyses of other micro- or macro-
eukaryote communities.
Bleaching of Symbiotic Algae (Zooxanthellae) and their Invertebrate Hosts: Causes and Mechanisms
William Fitt, University of Georgia
Bleaching, the loss of symbiotic dinoflagellates("zooxanthellae" hereafter) of their pigments, of reef corals and other
invertebrates has become a world-wide problem in tropical marine ecosystem, linked by some researchers to global
warming. The results of bleaching have potentially devastating environmental, ecological and economic effects in the
Caribbean, IndoPacific, an other tropical marine areas. Though there is some experimental work showing
involvement of both higher than average temperature and light, the mechanisms involved in bleaching are not well
understood this project will test three hypotheses. 1. Bleaching in nature is caused by high temperature stress coupled
with high energy blue light (and possibly UV-A between 380-400nm). Preliminary evidence shows that while high
temperature alone will induce bleaching, natural light exposure during high temperature treatment exacerbates the
effect by lowering the temperature threshold and time to bleaching at a given temperature. this study will determ
ine which component of light is responsible for this effect and the mechanisms of action. Early theories on bleaching
had light playing a major role, but experimental evidence has not yet supported this contention. Potentially harmful
chemical alterations associated with high energy wavelengths of blue light (and possibly some near-blue wavelengths
of UV-A, that are not adsorbed by UV-protecting pigments found in corals) are not only consistent with field
observations of bleaching, but are also supported by both laboratory and field-based preliminary experiments. 2. The
mechanisms of temperature-light induced bleaching involves the irreversible dissociation of the chlorophyll-protein
associations in the chloroplast. The harmful effects of high temperatures and light on algae include the irreversible
separation or inactivation of the chlorophyll-protein complexes associated with reaction centers in the chloroplast.
Electron transport activity and eventually carbon fixation decrease markedly. 3. High light and
temperatures cause decreases in "protective" pigments which absorb ultraviolet light. The role of different
wavelengths of light in conjunction with high temperature in determining concentrations of UV- screening pigments
will be determined as well as their relationship with photosynthetic rates. These hypotheses will be tested using
cultured and freshly isolated zooxanthellae, and intact hosts both in the laboratory and in field-based experiments.
El Nino Impacted Coral Reefs In The Tropical Eastern Pacific Secondary Disturbances, Recovery and Modeling of
Population and Community Responses.
Peter Glynn, University of Miami Rosensteil School of Marine and Atmospheric Sciences
This research will continue a long-term study that has focused on ecological disturbances to eastern Pacific coral reefs
that accompanied the sever and historically unprecedented 1982-83 El Nino-Southern Oscillation (ENSO). The study
involves international collaboration with host- county research teams and primary field sites in Costa Rica, Panama,
and the Galapagos Islands (Ecuador), areas heavily impacted by the 1982-83 ENSO. Dr. Glynn will lead the research
to continue (a) with the physical and biotic monitoring of eastern Pacific coral reefs initiated in the early-mid 1970s,
(b) investigating the responses of different coral species to ENSO stressors, (c) studying coral reproductive ecology as
it relates to recruitment success, and (d) documenting coral community recovery. New research directions include (e)
remote sensing, which will attempt to link coral bleaching/mortality with local and global scale sea surface
temperatures by means of synoptic and repeated measurements, and (f) modeling of coral pop
ulation and community dynamics based on mechanistic relationships between temperature, predation, coral growth,
and survivorship derived from field monitoring and experimental results. Because important secondary disturbances
are still occurring and reef recovery has been slow, it is necessary to continue this study in order to understand the
variety of changes involved and the full impact of a major disturbance on eastern Pacific coral survival and reef
building. We are hopeful that ENSO warming disturbances can provide some insight to the probable changes in coral
reefs worldwide if projected global warming causes repeated and/or protracted sea temperature increases comparable
to the 1982-83 ENSO.
Quantitative Aspects of Prey Chemical Defenses
Mark Hay, University of North Carolina Chapel Hill
This project will extend the PI's current investigations on chemical mediation of seaweed-herbivore and invertebrate-
predator interactions to include: (1) complex interactions of prey nutritional value with chemical and structural prey
defenses, (2) an understanding of how larval and spore defenses differ from those of the adult, and why (exposure to
different consumers?, increased exposure to UV without adult structures that provide shade?, etc.), and (3) the role of
learned aversion by vertebrate versus invertebrate consumers in affecting both prey and consumer dynamics. Because
benthic seaweeds and invertebrates play a trophically and ecologically important role in tropical and sub-tropical
near-shore communities and are rich sources of novel secondary metabolites that function as defenses against
consumers and have potential applications as pharmaceuticals, agrochemicals, and growth regulating substances,
understanding how these organisms respond chemically to ecological and environmental threats can pro
vide fundamental information about how marine systems function, and can suggest strategies for applied uses of
marine natural products.
Broadcast Spawning and the Population Ecology of Coral Reef Animals
Howard Lasker, State University of New York, Buffalo
The literature on marine benthic ecology and evolution has generally ignored fertilization rates as an important factor
in the life histories of benthic species, many which are important resource species. These rates have implicitly been
assumed to be uniformly high and thus not a terribly significant factor in the establishment of the adult populations.
There are now a number of data sets which raise doubts about the validity of that assumption. The research will
determine rates of fertilization among natural populations and will explore some of the factors controlling these rates
in reef communities. Using the Caribbean gorgonian, Plexaura A, as a model system Drs. Lasker and Coffroth will
determine rates of fertilization of eggs released in synchronous spawning events. Plexaura A is clonal and often has
skewed ratios of male and female colonies on different reefs. This will enable comparison of rates from reefs which
differ in current regime and in the density of male colonies. Using random amplified poly
morphic DNA (RAPD) from individual planulae larvae, they will conduct paternity analyses, determine the
proportion of fertilizations attributable to specific male clones, and determine the effects of clone size and
distribution on fertilization. If rates are low and are affected by factors such as population density, then it will be
necessary to incorporate fertilization rates in analyses of benthic population animal dynamics and evolution.
The Effects of Ultraviolet Radiation on Symbiotic Cnidarians: Action Spectra, Sites of Damage, and Bleaching
Michael Lesser, University of New Hampshire
The decrease of the stratospheric ozone layer has resulted in an increase in the amount of harmful ultraviolet
radiation reaching both terrestrial and aquatic ecosystems. Recent data indicates that this phenomenon will also affect
tropical ecosystems. Tropical ecosystems have a long evolutionary history of exposure to fluxes of UV radiation, and
can provide considerable insight into evolved mechanisms of protection against the deleterious effects of UV
radiation. We presently do not know with confidence the wave length-dependent efficiency (action spectrum) of UV
radiation for any physiological function in symbiotic cnidarians. Widespread coral bleaching events have recently
been observed following anomolously high sea surface temperatures around the world. If UV radiation synergistically
interacts with increased sea water temperatures, action spectra will be required to predict what dose of UV radiation
can induce bleaching, with or without an increase in sea water temperature. An important step in understa
nding the bleaching phenomenon is to determine the independent and synergistic effects of temperature, visible
radiation, and UV radiation on the functional biology of symbiotic associations.
A Facility for Research and Education at the Caribbean Marine Research Center, Lee Stocking Island Marine Field
Station.
Romuald Lipcius, College of William & Mary, Virginia Institute of Marine Science
The Caribbean Marine Research Center (CMRC) is one of six National Undersea Research Centers. CMRC's marine
field station on Lee Stocking Island (LSI) in the Exuma Cays, Bahamas comprises 28 buildings, a 915-meter airstrip,
nine research vessels, wet and dry submersibles, and recompression chamber and an underwater habitat. The station
affords access to a pristine marine environment with a diverse array of tropical habitats including shallow and deep
coral reefs, grassbeds, sand flats, mangroves, submerged carbonate terraces, subsea caves, blue holes, tidal channels
and stromatolites, a unique bio-geological feature. During 1993, 131 visiting scientists and students conducted
research in the fields of benthic ecology, invertebrate biology, fisheries ecology, oceanography, coral reef ecology,
paleo-oceanography, macroalgal ecology, aquaculture, global climate change, coral bleaching and marine geology. In
addition, a limited number of field courses and workshops were held at LSI. However, the station is hinde
red by a paucity of accommodations for visiting scientists, and the lack of a suitable lecture and workshop facility,
which prevents CMRC from meeting numerous requests to conduct field courses, workshops and research. The
proposed partnership between CMRC, The College of William & Mary (W&M), and NSF would significantly
enhanced the utility of one of the most productivity marine field stations in the Caribbean. Specifically this project
will provide for the construction of a dormitory and lecture/workshop building at LSI. Key contributions by CMRC
include property for the facility, support services, and administrative framework for coordination of activities, and
maintenance of the building over the facility's lifetime.
Path of Carbon in Photosynthesis and Release of Glycerol by Zooxanthellae
Leonard Muscatine, University of California Los Angeles
One of the most intriguing, and enigmatic phenomena in the field of coral reef ecology is the symbiotic relationship
between the coral polyp and the nutrient producing dinoflagellate that it hosts. This relationship is the key feature in
the stability of coral reefs and many of the organisms which reside there. The objective of this project is to study the
translocation of carbon from symbiotic dinoflagellates to the coral host cells. This will be achieved by a revolutionary
approach to studying this relationship, by artificially altering the biochemical carbon pathways, and evaluating the
subsequent metabolism of the coral polyp and the photosynthetic capacities of the dinoflagellates. This shall give us
new insights on the nutritional relationship between the two. Dr. Muscatine has a string of success with prior NSF
awards and is at the forefront in this field of study. His project will help to achieve two objectives: 1) further
contribute to our understanding of the role of coral symbioses, which could po
tentially have biotechnological value, and 2) provide another opportunity for collaborative work with Russian
scientist in U.S. laboratories.
Housing Facility for Visiting Scientists Award
Valerie Paul, University of Guam
The University of Guam Marine Laboratory will build a housing facility for accommodating visiting researchers
including visiting graduate students. The 2000 sq ft building will contain three bedrooms, 2 bathrooms, a kitchen,
and a living area for dormitory style accommodations and a separate suite with two bedrooms, one bath, and a kitchen
for an apartment style unit. Earlier support allowed the university to complete the architectural and engineering plans
for this building. Such a facility is considered extremely important because 1) the institution is in an isolated
academic environment and visiting investigators are a valuable resource for interactions and new ideas, and 2)
skyrocketing rents and a serious housing shortage combine to make it difficult to impossible to find adequate lodging
for visitors staying less than 6 months. The University of Guam Laboratory supports the research of 8 full-time
faculty, numerous graduate and undergraduate students, as well as visiting investigators. The research dem
ands on facility have increased due to the addition of new faculty at the laboratory, the recent establishment of
collaborative programs between the Marine Laboratory and the University of Hawaii and the University of the
Ryukyus (Okinawa, Japan), and the awareness of the Marine Laboratory as a resource for coral reef research by over
550 scientists who attended the 7th International Coral Reef Symposium on Guam in June 1992. The new building
will allow the support of increasing numbers of visiting scientists that wish to conduct research at the laboratory ,
which will in turn enhance the research environment.
Assessing the Chemical Defenses of Caribbean Sponges
Joseph Pawlik, University of North Carolina Wilmington
Sponges are important components of benthic marine communities, particularly on coral reefs. Organic extracts of
their tissues have yielded a wealth of unusual chemical compounds that are not known to be involved in primary
metabolism. These secondary metabolites have a diversity of pharmacological effects in laboratory assays, but it is
unclear why sponges produce them. The most commonly held theory is that these compounds are distasteful to
potential predators. The proposed research will provide an assessment of the chemical defenses of Caribbean demo
sponges, a group whose taxonomy and chemistry is fairly well described. The investigation will proceed within a
theoretical framework established by previous research on the chemical ecology of terrestrial plants and marine algae.
Overall, this research project represents the first systematic investigation of the chemical defenses of tropical marine
sponges. The results will be useful in judging the general applicability of optimal defense theories based on s
tudies of terrestrial ecosystems.
On the Abundance, Dynamics and Regulation of Damselfish Populations
Russell Schmitt and Sally Holbrook, University of California Santa Barbara
The aim of the work is to understand the dynamics and regulation of structured, open populations, which typify most
marine reef fishes and invertebrates. While there is broad agreement among ecologists that attributes of populations
are shared by more than an single process (e.g., availability of propagules, competition within and between life
stages, competition with other species, predation), there remains considerable disagreement regarding their relative
importance. There also is some confusion about what roles various processes have in producing dynamics; few
empirical workers have distinguished between processes that regulate populations (i.e., bound fluctuations) as
opposed to those that cause variation around the mean abundance. An enormous amount is known about the caused of
fluctuations in abundance of reef organisms, but very little is known about what regulates their populations. This
work will contribute in several key ways to understanding the general issue of dynamics and regulation. It is one
of the first comprehensive, pluralistic evaluations of reef fishes that will distinguish effects of processes on
regulation and on variation. Second, it will use for the first time operational definitions and analytical protocols for
quantitative assessments of the relative importance of various processes. As such, the research could yield standard
approaches and procedures to address relative importance. Third, the application of infrared video technology enables
the exploration of little studied but crucial processes of settlement and early mortality.
Zooplankton Capture by Corals: Effects of Water Movement and Prey Escape
Kenneth Sebens and Jennifer Purcell, University of Maryland
Information on water flow in coral reef environments has generally been done to quantify mass transport across reefs
or to identify important processes generating nutrient flux from reefs. This project will investigate the effects of water
flow on several aspects of the feeding biology of corals. Field measurements of feeding rates on four species of corals
will be made with prey sampling by an automated pump/sampler and field flume that allows concurrent
measurements of water flow and prey availability. Feeding experiments will be manipulated by varying flow rate,
prey type, and food availability and will be conducted over several days with different flow conditions. Capture
events and prey type, and food availability and will be conducted over several days with different flow conditions.
Capture events and prey escape behavior will be filmed using underwater video. Another important aspect of feeding
biology in coral reefs is the small scale water flow around corals in the field. This will be accomplished
with three self- contained underwater thermistors flowmeters with 2 mm spatial resolution, based on the design of
LaBarber and Vogel (1976). The data collected will be used to characterize the general flow regime at the site,
providing new information about the flow environment of coral reefs in Jamaica and other sites in the Caribbean.
Marine Biotechnology Fellowship: Natural Products from Common Shallow-water Soft Corals of Guam:
Reproductive Considerations
Marc Slattery, University of Mississippi (Formerly at University of Guam)
This research project will utilize analytical chemical techniques to evaluate the importance of secondary metabolites
and steroids in the reproduction of 3 species of soft corals from Guam. This project builds on ongoing research which
has identified and examined the importance of secondary metabolites, organic extracts, and morphological defenses in
soft coral predator deterrence. This project will extract, isolate, and determine the structures of new secondary
metabolites in adult colonies and their eggs. Temporal changes in concentrations of these compounds will be
correlated with reproductive indices to assess the role of the compounds in maturation and spawning. Standard
bioassays will be conducted to guide isolation of bioactive compounds and to determine the importance of isolated
natural products in egg release, sperm chemotaxis, and feeding deterrence. Novel compounds identified in this project
will expand upon a growing database of metabolites that can be used as chemotaxonomic markers and will be
incorporated into existing pharmacological programs. Additionally, this project will contribute significant in sights
into the reproductive biology and chemical ecology of the common soft corrals on the shallow reefs surrounding
Guam.
The Physiology of Sclerochronology: Mechanism and Variation in Formation of High Density Bands in the Massive
Coral Montastrea Annularis
Alina Szmant and Peter Swart, University of Miami, Rosensteil School of Marine and Atmospheric Sciences;
Richard Dodge, Nova University and James Porter, University of Georgia
High density (HD) bands mark annual cycles of growth in X- radiographs of reef coral skeletons and presumably form
due to physiological response to seasonal cycles of temperature and light. However, the mechanism of formation has
not been established for any coral. The HD band is usually used to define the annual band, and thus understanding its
formation, and the controls on variability in its timing is important. In the research, a conceptual model of how
density bands form, based on physiological and morphological data obtained with earlier NSF funding, is will be
developed. Four specific aspects of the work will include: (1) development of a mechanistic mathematical model for
the formation of the HD band of Montastrea annularis, a major coral used in paleoclimate work; (2) conducting an in
situ experiment to test the validity of the model; (3) evaluation of the genetic vs. environmental components of
variation in time of formation of the HD band; and (4) assessment of the variation among corals in the re
lationship between HD bands and stable isotope profiles. This study will provide the type of environmental
physiological data needed for the precise use of coral density bands for paleoclimatology.
Effects of Ultraviolet Radiation on the Biology of Caribbean Reef Corals
Gerard Wellington, University of Houston
Recent studies indicate that ultraviolet radiation can penetrate to considerable depths on tropical reefs. Persistent
high levels of UV penetration, resulting from extended periods of calm sea conditions, have been shown to induce
stress leading to the loss of symbiotic zooxanthellae (i.e., bleaching) in reef-building corals. These conditions may
have contributed significantly to the regional mass coral bleaching events observed in the Caribbean during 1987 and
1990. This project will continue monitoring penetration of UV radiation, sea temperatures, and recovery of coral
exposed to UV radiation. In addition, the project will be expanded to evaluate the effects of UV radiation on the early
life-history stages, namely planula larvae and newly-recruited juveniles, of predominant coral species. While
increases in UV radiation are predicted to be minimal at low latitudes, increased frequency of calm sea conditions
predicted by global warming will lead to enhanced water column clarity and high UV penetration with
subsequent negative effects on reef corals. This project, by experimentally defining the maximum UV intensities that
can be tolerated by larval and juveniles corals, will provide insight into the role that current intensities of UV
radiation play in limiting recruitment and shaping subsequent coral community structure.
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