Coral Reef Activities -- U.S. National Science Foundation

prtaylor at prtaylor at
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 

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 


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 

The Role of Heterotrophic Dinoflagellates in Marine Plankton Dynamics: Growth, Grazing Behavior and 
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 
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 
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 
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 

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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