WoRKSHOP ON CoRAL BLEACHING, CoRAL REEF EcosYSTEMs AND GLOBAL CHANGE: REPORT OF PROCEEDINGS

Brickell Point Sheraton, Miami, Florida June 17-21, 1991

Organizing Committee:

CHRISTOPHER F. D'ELIA ROBERT w. BUDDEMEIER Maryland Sea Grant College Kansas Geological Survey

STEPHEN v. SMITII University of Hawaii

Sponsored by:

National Science Foundation Environmental Protection Agency National Oceanic and Atmospheric Administration

Revised, September 1991

A Maryland Sea Grant ..College Publication Maryland Sea Grant College Publication Number UM-SG-TS-91-{)3 4 · q 5

Copies of this Maryland Sea Grant publication are available from:

Maryland Sea Grant College Taliaferro Hall University of Maryland College Park, Maryland 20742

This publication is made possible by grant #OCE-9113115, awarded by the National Science Foundation to the Maryland Sea Grant College Program. @ This publication is printed on recycled paper. TABLE OF CONTENTS

SUMMARY •••••• J••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• l INTRooucnotot ...... 2 Workshop Format and Venue ...... 2 Workshop Rationale and Background ...... ,...... 2 WORKSHOP PROCEEDIN(;S ...... 4 Organizing Committee's Overview ...... 4 Purpose of Overview ...... 4 The Bleaching Question- A Case Study ...... 4 Coral Reefs: Monitors of Environmental and Climate Change ...... 7 Environmental Factors and Their Effects ...... 8 Workshop Conclusions ...... 10 Ackriowledgrnents ...... 10 I CLIMATE WoRK GRoUP ...... 11 Su~roupI 1: Reef Response to Change ...... 11 I. Why Reefs? ...... 11 A. General Importance to the World ...... 11 B. Specific Importance to the U.S ...... 11 TI. Which Reefs? ...... 11 A. General Objectives ...... 11 B. Specific Criteria ...... 11 C. Suggestions (,.U.S. waters or government laboratories) ...... 11 Til. Complexity of the Problem ...... 11 A. Factors (in Isolation) ...... 12 I B. Interactions of Special Importance ...... 12 IV. Background Information Required for Planning Studies ...... 12 A. Projections for Future Climate Change ...... 12 B. Information on Past Conditions and Communities ...... 12 C. Basic Information on Nature and Mechanisms of Biological Interactions ...... 12 D. Systematics ...... 12 V. General Experimental Protocol ...... 12 A. Cell Biology- Laboratory Experiments ...... 12 B. Physiology- Laboratory Experiments ...... 13 C. Individual Growth Experiments ...... 13 D. Community Structure Experiments ...... ;...... 13 VI. Species to be Studied ...... 13 A. Model Systems ...... 13 B. Other Important Species ...... 13 VI 1. Priorities For the Next Five Years {Unranked) ...... 13 I A. Experiments to Determine Responses of Model System Species ...... 13 I B. Establishment of a World-wide Monitoring System ...... 13 C. Development of Microcosm Facilities...... 13 D. Increased Use and Development of Complex Model Simulations...... 13 E. Publication of Manuals with Workable Keys ...... 13 1 Vij:l. Experimental Protocols- Details for Specific Factors ...... 14 ' A. Sea Level Rise ...... 14 B. Temperature ...... 14 C. Ocean Currents and Wave Climate ...... 14

iii D. Storms ...... 14 E. Radiation (U.V. and visible) ...... 14 F. Sedimentation and Turbidity ...... 14 G. Nutrients ...... 14

H. C02 •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 14 I. Toxic and Artificial Substances ...... 14 J. Overfishing and Related Activities ...... 14 Sub-Group 2: History of Environmental and Ecological Variability ...... 14 I. Introouction ...... 14 A. Contributions from the Paleoenvironmental Records of Reefs ...... 15 B. Ecological and Paleoecological Studies ...... 15 C. Rates of Climate Change and Coral Response ...... 15 D. Monitoring, Calibration and Quality Control ...... 15 E. Summary ...... 15 Sub Group 3: Data Required by Researchers ...... 15 I. Issues ...... 15 A. Role of Oimate Models and Issues Related to Models ...... 15 B. Distinguishing Anthropogenic from Global Climate-Change Signals ...... 17 C. What are the Monitoring Requirements? ...... 18 D. What Historical Data are Available for Correlation? ...... 18 E. Value of Reefs to Reinforce the Research Efforts Being Generated ...... 19 II. The Need for Remote Sensing of Coral Reefs ...... 19 CoRAL BLEA.OJING WoRK GRoUP...... 20 I. The Nature of the Bleaching Phenomenon ...... 20 A. Specific Questions Addressed: ...... 20 B. Summary ...... 21 C. Research Priorities ...... 21 II. Coral Stress, Bleaching, and Retrospective Studies ...... 22 A. Background ...... 22 B. Research Priorities ...... 23 III. Coral-Algal Functional Biology ...... 23 A. What Factors Contribute to the Stability of the Coral-Algal Symbiosis...... 24 B. Manifestations of Destabilization of the Symbiosis ...... 24 C. Individual Variation and Susceptibility to Bleaching...... 24 IV. Long-Term Ecological Consequences ...... 24 A. Background ...... 24 B. ·Research Priorities ...... 24 ORGANIZERS' NarE ON MoNnuRING ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 25 Development of a Monitoring Program: Philosophy and Rationale ...... , ...... 25 FINDIN(;s AND RECOMMENDATIONS ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• •••••••••••••••••••••• ••••••••• •••• •••••••••••• 27 APP~DIX A ...... 29 Status of Knowledge on Coral Reefs and Climate Change Issues ...... 29 I. Climate/Environmental Change ...... 29 II. Paleoclimate Studies ...... 29 lli. Reef Responses to Environmental Parameters ...... 30 IV. The Bleaching Question ...... 34 V. Resource Utilization ...... 35 VI. Integrated Issues - Research and Monitoring ...... 36 VII. Communication and Implementation ...... 36

iv APPENDIX B...... 37 Development of a Monitoring Program: Practical Recommendations ...... 37 APPENDIX c !...... 41 Wri~ten Materials Submitted to the Workshop ...... 41 Ad Hoc Plenary Talks, June 19, 1991 ...... 44 APPENDIX D ...... 44 Abstracts of Invited Plenary Talks ...... 44 Coral Reefs, Climate, and Environmental Change ...... 44 Coral Bleaching: A Cell Biological Perspective ...... 46 Systems Level Management, Monitoring and Research: The Australian Perspective on Environmental Change ...... 47

v are also known to cause bleaching, and our knowledge SUMMARY of both coral stress responses and the detailed nature of climate change make it impossible at present to claim A works"op on coral reef ecosystems and global that coral bleaching is an early indicator of the global change was held June 18-21, 1991 in Miami. The greenhouse effect. This detailed finding was seen as meeting was s}>onsored by the National Science strong reinforcement of the perceived need for system­ Foundation, the National Oceanic and Atmospheric atic monitoring as a basis for research. Administration, and the Environmental Protection In identifying the probable present and future Agency in response to rising concerns about widely environmental threats, the workshop found that reported episodes of coral reef "bleaching" and deterio­ although global climate change represents an impor­ rating ecosystem health and reef environmental tant long-term challenge, the most immediate concerns quality. and the strongest stresses and environmental "signals" The workshop had three specific aims: stem from local and regional anthropogenic sources­ •To examine recent evidence about the phenom­ the results of human population growth, land use, enon of cqral bleaching and to determine what resource exploitation, waste disposal, etc. Such effects additional approaches and information are correlate and interact with environmental signals needed. resulting from longer-term climate change and from natural environmental variability. A matter of particu­ •To understand and predict the responses of lar concern is the sometimes subtle effect of long-term coral reefs to global climate change. nutrient loading in coastal areas or enclosed basins. •To suggest priorities for future research to Physiologists are making substantial strides in provide agencies with a starting point for developing a mechanistic understanding of bleaching developing further initiatives. and other stress responses. Ecological, environmental, The group of international experts that attended and climatic data will take longer to develop and the meeting cf.nsisted of approximately fifty scientists understand. The group endorsed the importance of representing fisciplines ranging from coral biology, redressing this imbalance with "retrospective monitor­ ecology, and geology to climate modeling, oceanogra­ ing''- the use of environmental information contained phy, and meteorology. In response to the objectives of in the chemical and physical records of the annual the workshoP,, the group reviewed and produced a growth bands of corals to reconstruct environmental series of docJments defining the status of present variations and organism responses of the recent past. knowledge about coral reefs and the environment, as Reefs are ecologically and structually important well as identifying key research and information needs features; they are important resources, both economi­ for the future. The present report represents a compila­ cally and in terms of biodiversity; they have potential tion of these documents. to serve as sensitive environmental recorders and A major conclusion of the group was that much indicators, particularly of the wlnerable and important subjective evidence exists to indicate that there is a coastal and shallow-water regions of the world's worldwide decline in the overall"health" of coral reef tropical and subtropical regions. It is important to note, and related eCosystems, but there arc not adequate however, that they are not sinks for atmospheric baseline and ~urvey data to provide a rigorous scien­ carbon dioxide; contrary to some assertions, on time tific assessment of the nature and extent of the prob­ scales of concern to humans, marine calcium carbonate lem. The group therefore strongly recommended the production results in the release rather than the absorp­ development and expansion of a scientifically based, tion of atmospheric carbon dioxide. On the scale of internationally coordinated long-range monitoring anthropogenic carbon dioxide releases, however, reef­ program orie'nted toward reef environments and induced fluxes are insignifcant. ~ssembled biology. The experts emphasized in very The interdisciplinary and issue-oriented nature of strong termslthat such a program would yield immedi­ the workshop resulted in a strong emphasis on time ate importan~ results in terms of major theoretical and scie~tific and space scales and on environmental interactions not applied questions related to spatial variations, normally emphasized in more traditional conferences. in addition to providing the longer-term data base The workshop organizers hope that the present docu­ needed for other studies. ment provides a starting point for the development of With rdpect to the issue of coral reef ''bleaching," an international and interdisciplinary research effort to the group cohcluded that recent increases in reported evaluate the response of coral reefs and other shallow events were indicative of increasing ecosystem stress, water tropical marine ecosystems to global climate and that many of the events appear to be associated change. with local high temperatures. However, other stresses

1 "Issues List" (Appendix A) before the meeting, and INTRODUCTION were asked to come prepared to critique it. In a further effort to provide all participants with the latest infor­ mation on the state of our knowledge about coral Workshop Format and Venue bleaching and the response of coral reefs to global change, four leading scientists were invited to make The workshop on "Coral Bleaching, Coral Reef plenary introductory presentations. Thereafter the Ecosystems, and Global Change" was convened in group subdivided into two groups, the "climate Miami from June 17-21, 1991. This was undertaken as a group," and the "bleaching group" for intense delib­ scientific community activity with joint support by the erations. Two final plenary sessions occurred, one for a National Science Foundation, the Environmental series of five-minute contributed talks, and the other a Protection Agency, and the National Oceanic and final session on the last day to review the proceedings Atmospheric Administration. The three coordinators of the workshop and come to consensus on conclu­ were: Christopher F. D'Eiia (Maryland Sea Grant sions. College), Robert W. Buddemeier (Kansas Geological A complete agenda for the workshop is given in Survey), and Stephen V. Smith (University of Hawaii). the accompanying table. The Federal coordinator was Phillip R. Taylor, National Science Foundation. Logistical considerations were Workshop Rationale and Background coordinated by the Maryland Sea Grant College. The workshop had three specific aims: The issue of climate change has, in the space of a few years, shifted from a subject of specialized scien­ •To examine recent evidence about the phenom­ tific interest to a major focus attention in the public and enon of coral bleaching and to determine what in national and international agencies, with a U.S. additional approaches and information are Global Oimate Research Program being articulated by needed. the Committee on Earth and Environmental Sciences •To understand and predict the responses of (CEES). This rapid escalation to an issue of policy and coral reefs to global climate change. applied science has bypassed the normal process of •To suggest priorities for future research to gradual diffusion of concepts into other scientific provide agencies with a starting point for disciplines. A coherent, cost-effective analysis of the developing further initiatives. important issues requires effective interdisciplinary communication and planning. An operational goal of the workshop was to produce a working document, generated during the Shallow tropical marine environments, and in meeting, to assess our state of knowledge about the particular coral reef ecosystems and adjacent commu­ phenomenon of coral bleaching and the sensitivity of nities, may be especially vulnerable to the effects of coral reef systems to environmental change, and to climate change. In addition to, and in part because of articulate and recommend research priorities for coral these vulnerabilities, coral reef research may be pre­ reef ecosystems in the context of global climate change. sented with opportunities to: (1) contribute to a devel­ The present document includes the results of that effort oping understanding of the detailed nature and effects (i.e. "the work group reports") as well as some supple­ of climate change; (2) exploit that change as a large­ mentary material provided to summarize and clarify scale experiment to understand the response mecha­ the more detailed work group reports. nisms of reef ecosystems; and (3) use these systems as early indicators of environmental change. Participation in the full workshop was by invita­ tion only, owing to limited space, funding, and a need Coral reefs are geologically ancient ecosystems to have international representation from a broad that have provided excellent paleoecological evidence variety of disciplines (see accompanying table). How­ of past global climatic changes and some of the best ever, the workshop is regarded as a first step in a indications extant of ecosystem response to such process involving a much broader segment of the changes. Coral reefs arc believed by some to be indica­ scientifij; community, and thus opportunities to tors of global climate change in more than just the participate in the process exist for those who were not geological record; there has been considerable recent present. Indeed, an initiative based on this workshop speculation in the press, discussion among reef re­ will require substantial participation by a larger group searchers, and testimony in Congress on the topic of of individuals than were present in Miami. coral"bleaching." To provoke thought and provide a point of Two hearings have been held (one in 1987, the departure for people with varying disciplinary back­ other in 1990) in the U.S. Senate addressing the bleach­ grounds, all workshop participants were sent an ing issue, i.e. , the phenomenon of hermatypic corals

2 Workshop on Coral Bleaching, Coral Reef Ecosystems and Global Climate Change Brickell Point Sheraton, Miami, Florida June 18-21, 1991 Agenda

TUESDAY, JUNE 18 5:30-7:00 Reception at Rosenstiel School of Marine and Abnospheric Science, Public Plenary Session 4600 Rickenbacker Causeway, Miami

9:00-9:30 Introductory Remarks WEDNESDAY, JUNE 19 Christopher D'Elia Maryland Sea Grant College 8:30am Workshop- Groups will reconvene with the option of breaking into smaller 9:30-10:00 Agency Perspectives groups. Phillip R. Taylor National Science Foundation 12 noon Lunch

10:00-10:30 Coffee Break 1pm Workshops (continued)

10:30-11:30 Systems Level Management, 4 pm Plenary Sessions (participants)­ Monitoring, and Research: Workshop progress to be discussed. The Australian Perspective on Environmental Change TllURSDAY, JUNE 20 Donald W. Kinsey Great Barrier Reef Marine Park 8:30am Workshop - After assessment of Authority, Townsville progress, working groups will recon­ vene, with refinement of goals and 11:30-12:45 Lunch exchange of participants if appropriate.

12:45-1:45 Coral Reefs, Environmental Change, 12 noon Lunch and Global Climate Issues Robert W. Buddemeier 1 pm Workshop- Reports from the working Kansas Geological Survey, Lawrence groups will be assembled.

1:45-3:15 Coral Bleaching: Ecological and Cell 5 pm Break for evening meal Biological Perspectives Leonard Muscatine 7 pm Complete assembling of reports University of California at Los Angeles Peter Glynn FRIDAY, JuNE 21 Rosenstiel School of Marine and Atmospheric Science 8:30am Summary and report presentation

End of Public Plenary Session 12 noon Lunch and Departure

3:15-3:30 Coffee Break 1 pm Conference organizers and key indi­ viduals reconvene for post-workshop 3:30-5:00 Workshop -Two working groups will discussion. be convened to discuss and respond to the Plenary Session presentations.

3 losing their algal endosymbionts, the zooxantheUae. In potential global climate change on shallow water fact, the fi'91 Senate appropriations bill for NSF tropical marine ecosystems such as coral reefs. required NSF to develop by May, 1991, a plan to address research on bleaching and reefs in the context WORKSHOP PROCEEDINGS of global change. The view of several panelists who testified was that ~levated sea surface temperatures Organizing Committee's Overview (SST's) are likely to be the cause of the bleaching, and that the phenomenon was the harbinger of global Purpose of Overview warming. Wary heads of federal agencies represented This overview of the workshop proceedings was at the hearings have sensed the need to cover their prepared by the organizing committee neither to bases - not only for political reasons, but also because duplicate nor replace the output of the working o~ co?cem about the sdentific basis for legitamately groups, but rather to provide integrative comments vtewtn~ the phenomenon as an indicator. Accordingly, and highlights of the discussions and submissions in th_e toptc of coral bleac~ng as an indicator of global the context of the overall results of the workshop. chmate change has parttcular currency in Washington. Although every effort has been made to reflect the :While th~ present interest in coral bleaching has spirit of the discussions and to ensure consistency with certamly motivated a response by politicians and the :working ~oup reports, it was deemed impractical sdence policy makers, there are sound a priori scientific to orculate th1s summary to all participants for review. reasons why coral reef ecosystems (which are used Therefore it cannot necessarily reflect the views of all of here as a convenient proxy term for a range of related the participants. In the text that follows, an author or associated tropical marine communities, including citation refers to the oral or written presentations sea grasses and mangroves) need more attention than submitted to the workshop; these are listed in Appen­ they have traditionally received: dix C. • Tropical coastal systems such as coral reefs are extremely vulnerable to the current scenarios of The Bleaching Question-A Case Study envir~nmental perturbations, because many orgarusms of reef systems exist near upper limits Physiology. Bleaching, the loss of symbiotic algae of thermal tolerances in shallow seas that are by reef corals and other symbiotic organisms, is more susceptible to temperature excursions; recognized as stress response to a variety of environ­ mental perturbations, among them extremes of light, • Little attention has been paid to tropical coastal temperature, and salinity. Muscatine (plenary) pre­ systems in climate change research and plan­ sented research results suggesting that the mechanism ning, yet these systems may be important sinks for loss of zooxanthellae involves cell adhesion and sources of greenhouse gases; disfunction. Under stress, host cells containing zooxan­ • Reef systems are sensitive to locally generated thellae may lose their ability to adhere to the tissue factors such as sedimentation and nutrient layer with which they are associated and are subse­ loading, which may interact synergisticaUy with quently expelled from the host. The process occurs in the effects of climate change; stressed aposymbiotic coelenterates, but is enhanced • Reef systems may provide '1itmus" tests for the when symbiotic algae are present. This interaction of response to climate changes (e.g., coral bleach­ the algae with the host animal's stress response identi­ ing, invertebrate die-offs, etc.); fies a possible pathway for stress synergism; conditions that affect physiology or population of the algae (e.g., • Reefs are valuable natural resources in terms of light, nutrients) may indirectly alter the host's suscepti­ biological diversity, fisheries, coastal protection, bility to bleaching in response to other stresses. and tourism. Environmental Correlates. A significant impetus for With the previous information in mind, it now this workshop was the debate about whether the seems timely to consider carefully what is known recently reported increases in the incidence of coral reef about coral reef ecosystems, particularly in the context bleaching were real, and if so, the significance of these of global climate change. Accordingly, the National observations with respect to general ecosystem Science Foundation, the Environmental Protection "health" and the possible effects or detection of global Agency and the National Oceanic and Atmospheric climate change. Administration sponsored a workshop directed to understanding the state of our knowledge about reef There have been suggestions that increased ecosystem health, including the issue of coral bleaching bleaching is the result of increases in temperature that and, in the larger sense, to consider research needs for might be attributable to global climate change (Goreau the next decade for understanding the effects of et al., Bunkley-Williams and Williams). Halley and

4 Organizers, Staff, Federal Agency Representatives and Invited Participants

Organizers and Staff Federal Agency Representatives Deborah Santavy U.S. EPA Amy Broussard Brad Brown Environmental Research Texas Sea Grant College Southeast Fisheries Center Laboratory Texas A&M University NOAA/NMFS Sabine Island P.O. Box 1675 75 Virginia Beach Drive Gulf Breeze, FL 32561 Galveston, Tic 77553-1675 Miami, FL 33149 Marsha Sitnik Robert W. Buddemeier Billy Causey National Museum of Natural Kansas Geological Survey LooeKeyNMS History 1930 Constant Ave. NOAA Room421 Campus West Route 1 Box 782 Smithsonian Institution Lawrence, KS 66047 Big Pine Key, FL 33043 Washington. DC 20560

Christopher F. O'Eiia Peter Comanor Sea Grant College Program National Park Service Invited Participants H.J. Patterson Hall Wildlife and Vegetation University of Maryland P.O. Box 37127 Bruce Chalker College Park, MD 20742 Washington, DC 20013 Australian Institute of Marine Science Daphne Fautin William Davis P.M.B.No.3 Dept. of Systkmatics and Ecology U.S. EPA Townsville, QLD 4810 Snow Museum Environmental Research AUSTRALIA University of Kansas Laboratory Lawrence, KS 66045 Sabine Island Julia Cole Gulf Breeze, FL 32561 Lamont-Doherty Geological Mary Griffin Observatory Sea Grant College Program George D. Dennis Palisades, NY 10964 H.J. Patterson Hall Caribbean Marine Research Center University of Maryland 805 E. 46th Place Joseph Connell College Park, MD 20742 Vero Beach, FL 32963 Department of Biological Sciences I Univ. of California, Santa Barbara William E. Kiene Mark Eakin Santa Barbara, CA 93107 2013 NSt. N.W. SSMC-1, R/CAR Washington, DC 20036 NOAA Margaret Delaney 1335 East-West Highway Institute of Marine Sciences Stephen V. Smith Silver Spring, MD 20910 Univ. of California, Santa Cruz Department .of Oceanography Santa Cruz, CA 95064 University of Hawaii Gary Hendrix Honolulu, HI 96822 National Park Service Terry J. Done Rm.1092 Australian Institute of Marine Phillip R. Taylor 75 Spring St., SW Science Biological Oceanography Program Atlanta, GA 30303 P.O. Box3 National Science Foundation Townsville, QLD 4810 1800 G Street, NW Paul Ringold AUSTRALIA Washington, DC 20550 U.S. EPA 401 M St.,SW RD-682 Washington, DC 20460

5 Zvy Dubinsky Paul J. Jokiel Department of Life Sciences Hawaii Institute of Marine Biology Caroline Rogers Bar-Dan University P.O. Box 1346 Virgin Islands National Park RamatGan Kaneohe, Hl96744 P.O. Box710 ISRAEL 52900 St. John, USVI 00830 Donald Kinsey Robert Dunbar Great Barrier Reef Marine Park Claes Rooth Department of Geology Authority RSMAS Rice University P.O. Box 1379 University of Miami Houston, TX 77251-1892 Townsville, QLD 4810 4600 Rieken backer Causeway AUSTRALIA Miami, FL 33149 Joe Elms National Oimate Data Center Nancy Knowlton Robert Rowan Federal Building Smithsonian Tropical Research Hopkins Marine Station Asheville, NC 28801-2696 Institute Stanford University Box2072 Pacific Grove, CA 93950 David Enfield Balboa, Panama NOAA/AOML GlenShen Physical Oceanography Michael Lesser School of Oceanography Department Bigelow Laboratory for Ocean WB-10 4301 Rickenbacker Causeway Sciences University of Washington Miami, FL 33149 McKown Point Seattle, WA 98195 W. Boothbay Harbor, ME 04575 Peter Glynn Malcolm Shick Division of Marine Biology and Yossi Loya Univ. of Maine, Orono Fisheries Dept. of Zoology Department of Zoology Rosenstiel School Tel Aviv University Orono, ME 04469 4600 Rieken backer Causeway Tel Aviv Miami, FL 33149 ISRAEL 69978 Gerard Wellington Department of Biology Robert Halley George Maul University of Houston U.S.G.S. Coastal Center NOAA/AOML Houston, TX 77204-5513 600 S. 4th Street 4301 Rieken backer Causeway St. Petersburg, FL 33701 Miami, FL 33149 Robert Wicklund Caribbean Marine Research Center Pamela Hallock-Muller Linda Mearns 1501 North Pointe Parkway Dept. of Marine Science NCAR Suite 102 University of South Florida P.O. Box 3000 West Palm Beach, FL 33407 St. Petersburg, FL 33701-5016 Boulder, CO 80307 William J. Wiebe David Hopley Leonard Muscatine Department of Microbiology Sir George Fisher Centre for Department of Biology University of Georgia Tropical Marine Studies UCLA Athens, GA 30602 James Cook University Los Angeles, CA 90024 Townsville, QLD Ernest Williams AUSTRALIA 4811 William Quinn Department of Marine Sciences College of Oceanography University of Puerto Rico Jeremy Jackson Oceanography Administration P.O. Box908 Smithsonian Tropical Research Building Lajas, PR 00667 Institute Oregon State University Box2072 Corvallis, OR 97331-5503 Charles Yentsch Balboa, Panama Bigelow Laboratory for Ocean Eugene Rasmusson Sciences Department of Meteorology McKown Point University of Maryland W. Boothbay Harbor, ME 04575 College Park, MD 20742

6 Hudson (also, Hudson et at.) showed that there was no geologic record is a limited source of insights into our reliable correlation between temperature and bleaching present situation. on the basis of a long-term monitoring program in the Today's reef organisms and communities come to Florida Keys. Although particular instances of bleach­ us through the filter of the Quaternary climate oscilla­ ing were attJibuted to high temperature, other episodes tions- and have arrived with minimal evidence of of similarly high -or even greater- temperature change or extinction along the way. Jackson noted that were not accOmpanied by bleaching. Kinsey (plenary) the zonation and community structure of Caribbean cautioned that it can be very difficult to identify the reefs seems to have been the same in the Pleistocene as proximate cause of bleaching, for triggering events it is today. Although this robustness is encouraging may be transient, and by the time bleaching is noticed from the standpoint of probable survival, the time (even the following day), it can be attributed to a resolution of the fossil record is far too coarse to different environmental perturbation. Elms presented provide information about responses on the time scale 40-year records of sea surface temperature for the of present-day human observations (Buddemeier and greater Gulf-Caribbean area that indicated an overall Hopley). temperature decrease during that period. The space and time scales of climate are by Perceptions of the bleaching phenomenon showed definition global and long-term, while coral reef strong regional differences. Kinsey (plenary) stated that observations tend to be local and of limited duration the Great Barrier Reef had shown no significant (Buddemeier, plenary). Relating reef or organism increase in the amount of bleaching, and that a majority responses to local or regional environmental change is of the bleaching episodes observed were related to a practical and worthwhile objective, but determining stresses other than high temperature, often low tem­ responses to a specific climatic component of environ­ perature. Glynn (plenary) reported on his extensive mental change will require careful design and intensive work with Eastern Pacific bleaching, which was due to data collections that do not currently exist. In any case, tempe~ture co~ditions. high resulting from El Nino In a useful perspective to maintain is that reefs respond general, Caribbean workers were most convmced that directly to short-term and local effects (e.g., eutrophica­ o~serving they were real increases in bleaching that tion) and less directly to long-term and regional effects were related! to elevated temperatures, but could not be (e.g., biogeography). attributed to a specific, identifiable phenomenon such as El Nino. It was recognized that an increase in the Participants emphasized the importance of reef frequency o6 brief high temperature excursions in ecosystems on both scientific and practical levels. Reef communities (or related communities) either do or can shallow water was not necessarily inconsistent with the data from shipping lanes presented by Elms. occupy much of the coastal zones or shallow-water areas in the tropics and sub-tropics-a significant Both the "climate" and ''bleaching" working fraction of the world's total. These same areas are home groups considered in some detail the issues of climate to large and growing human populations, for which signal prediction, identification, and detection, particu­ the coastal marine communities provide important larly with reSpect to uncertainties in the database immediate resources in addition to their larger role in (Maul) and problems of the scales of the effects and the global biodiversity. In spite of their importance on a observations. Some of these issues are discussed variety of levels, coral reef C02 fluxes are not a factor further in the section on sensitivity below. The overall in climate change (Smith; Kinsey and Hopley); the conclusions reached were that (1) there probably have global reef-induced net calcification flux is insignificant been some regional increases in the frequency of compared with anthropogenic C02 releases. Contrary bleaching, (2) some of these appear to be related to high to frequently expressed assumptions, marine calcifica­ temperature events, but (3) these are best regarded as tion is a source rather than a sink for atmospheric C02 indicators of environmental stress and cannot be on time scales relevant to rapid climate change (Ware considered indicators ofglobal climate change. et al.; Smith). I Real-time Observations and Retrospective Records. Coral Reefs: Monitors of Environmental and Climate Workshop participants generally agreed that subjective Change evaluation of trends in coral reef observations suggest Scales and Sensitivities. Because of their obligate an increase in reef stress and a deterioration in the relationships to light, temperature, and sea level, corals "health" of reef environments. However, quantitative and reefs have long been regarded as both vulnerable examination of the possibility of climate trend detec­ to climate change and reliable indicators of past tion by population and community changes (Connell) climate. Although this is true in a broad sense, the revealed a requirement for long-term observations of large numbers of samples- which do not exist at present. A signal/noise evaluation of coral bleaching as

7 an indicator of global temperature trends (Ware and Climate change appears most likely to account for

Reaka-Kudla) suggested that a mean temperature changes in temperature, global sea level, C02 chemistry increase on the order of a degree would be required to of the oceans, incident visible light, and current, wave, bring the climate-induced bleaching signal above the. and storm regimes; it may also be a significant factor in noise of natural climate variability. Few would argue changes in fresh water and related fluxes, especially that such a temperature change has occurred as yet. near land masses. Other (non-climatic) sources are The problem of interpreting responses to environ­ likely to dominate near-term changes in the effects of mental change is further complicated by sensitivity ultraviolet light, nutrient loading, sedimentation, toxic variations within and between taxa, and by uncertain­ chemicals, turbidity, some aspects of fresh water ties in the taxonomy of both corals (Knowlton et at.) delivery, and human exploitation of resources (e.g., and their algal symbionts (Rowan). Knowlton volun­ fisheries). It is particularly significant that most of the teered to serve as collector and collator of records of non-climate stressors are delivered primarily through reef surveys over time that might produce specific data the hydrologic pathway; unlike the atmospheric and on trends, and asked participants to notify their hydrographic pathways, the hydrologic pathway has colleagues and send her any available data. In subse­ an amplifying effect on environmental change signals. quent discussion, Connell pointed out that coral reef Runoff can integrate the effects of precipitation, scientists tend to select healthy reefs for study, thus pollution, erosion, or other terrestrial changes over biasing subsequent observations against possible areas ranging from watersheds to significant fractions improvement and in favor of deterioration. Overall, of continents (e.g., the Mississippi River drainage) and participants recognized that rigorous characterization focus the products into restricted coastal zones or of either ecosystem health or environmental trends basins. would require more extensive, longer-term, and better­ For these reasons and because of recognition of coordinated observations than currently exist. the current importance of widespread local and The use of retrospective records to reconstruct regional anthropogenic stresses on coral reefs, there proxy baselines for variables without adequate histori­ was general agreement that at present and for the cal records received considerable attention. Since coral coming years to decades, anthropogenic stresses skeletal growth bands contain both an intrinsic chro­ resulting directly from population growth and devel­ nology and physical, chemical, and isotopic records of opment are the strongest environmental signals and various aspects of their depositional environment the greatest threats to coral reefs. Impacts of these (Dunbar and Wellington, Shen), it is possible to de­ stresses will be preferentially felt by reefs experiencing velop time series of both environmental variation and the influence of land masses. Climate change is a coral responses, providing a partial substitute for the significant factor in ·the future of coral reef ecosystems, missing records. After a thorough discussion of appli­ but on a somewhat longer time scale; its effects will be cations, potential limitations, and uncertainties, both felt (although not necessarily to the same extent) by working groups recommended increased emphasis on both oceanic and nearshore reef systems. It must be the use of retrospective records to expand understand­ emphasized that separation of "climatic" and "other'' ing of past environmental changes and their effects on stresses is a convenient but arbitrary conceptual device; corals and their communities. a scientifically sound approach to addressing the impacts of environmental change on time and space scales appropriate to the distribution and development Environmental Factors and Their Effects of reefs must deal with both sources and their various Dominant Sources of Near-tenn Stress. The work­ combinations. shop used and reviewed a draft list of environmental Non-climate Stresses. Among the potential stres­ factors known to influence or stress coral growth and sors likely to arise from non-climatic environmental reef development. The revised version of that list is alteration, the two most prominently considered were presented in appendix A as a summary status of increased ultraviolet light flux and nutrient (or sedi­ present knowledge on reef-environment interactions. ment) loading. The UV exposure problem is global in Buddemeier (plenary) suggested two possible ap­ scale as a result of stratospheric ozone depletion, and proaches to classifying present and potential future although subsurface flux data are scarce, there is coral reef stresses: (1) whether they were more likely to substantial evidence that UV light is a significant result from climate change or from other non-climatic stressor for shallow-water corals (Wellington and but probably anthropogenic sources; and (2) by the Gleason; Shick and Lesser). Nutrient loading was dominant pathway of delivery of the stressor to the identified as a subject of major concern on the Great reef-atmospheric, hydrographic, or hydrologic. Barrier Reef (Kinsey, plenary) and in the Gulf/Carib­ bean system (Hallock-Muller), which receives runoff of

8 increllSing nutrient concentration from both the North SST, but calibrations against present climate were not and South American continents. Hallock pointed out always impressive, and the model oceans are highly that Mississippi River effluent has undergone an simplified. Paleoclimate studies suggest that tropical increase in nitrate concentration of nearly an order of regions may have been no warmer, and possibly even magnitude ~approximately 20 years. High nutrient cooler, than present during past warm periods levels function as a chronic stress that can cause a shift (Buddemeier, plenary). Because of the known sensitiv­ to algal dominated communities if coral communities ity of corals and other reef organisms to elevated are killed or destabilized by an acute stress. They may temperature (Glynn, plenary), the question of whether also have significant direct effects on reef organisms; there will be significant tropical SST increases is Hopley showed abnormal calcification resulting from almost certainly the most important specifically phosphate loading, and Muscatine (plenary) discussed climatic question relevant to coral reefs. Accordingly, the effects of nutrients on the growth and standing a crucial issue for physical oceanographers and clima­ stock zooxanthellae in corals. tologists to resolve will be what regulates SSTs and The current primary sources of high nutrient whether feedback mechanisms (e.g., cloud formation) levels are waste disposal and land-use practices exist that create upper limits to SSTs. (deforestation, agricultural fertilization); the effects are Consequences, Uncertainties, and Research Needs. In thus concentrated in the vicinity of land masses, and general, the effects of many types of environmental are often accompanied by" increases in the more local­ change on corals and reefs are reasonably well under­ ized effects of sedimentation, turbidity, fresh water, stood; they are summarized in the status-of-knowledge and the concentration of biocides or other toxic chemi­ list (Appendix A), and discussed here and in the cals. In the longer term, climate-induced shifts in working group reports. Three critical areas of igno­ upwelling and circulation may increase or decrease rance can be identified. One is outside the realm of oceanic nutrients levels on a regional basis, but such specifically reef-related studies, and involves the possible effects are not currently predictable, and uncertainties in climate models and predictions. As appear at present to be minor compared to anthropo­ climate and ocean models improve and as the signal of genic discharges. climate change emerges from the noise, we may expect An ad~itionallocally significant non-climate significant improvements in further predictions. It will factor is resource exploitation; on land it may increase be important for the reef research community to stay the impacts of terrigenous stressors (erosion, agricul­ abreast of these developments. A second area, in tural chemibals), but one of the primary marine ex­ which some research is already occurring, is that of amples is local fisheries. Herbivorous reef fish are an synergism or interactions between multiple stressors, important ecological balance on algal growth, and their at both organism and the community levels. We know removal can exacerbate the problems of increased algal that this is an issue and what to look for, but we are far standing stock due to increased nutrients or substrate from having either predictive mechanistic models or modification. reliable empirical calibrations. Third, we have neither the records nor the models needed to understand the Climate-related Stresses. Oimate-related changes in long-term effects of either persistent or transient storms, wa~es, currents, and incident visible light will environmental perturbations - that is, how popula­ be local or regional in their effects, are not at present tion dynamics and community structure respond to predictable, and probably will not result in a net perturbations on time scales relevant to the lifetimes of increase in reef stress when viewed in global terms and the framework corals and the geological development in the context of natural variability. Sea level rise, at of reef structures. the rates presently forecast for the next century (in­ creases of ~few mmlyr), was also not seen as a major Research and Monitoring. The working group source of additional reef stress overall, and might, documents present specific recommendations for ironically, prove to have a net beneficial effect. The research priorities that will not be duplicated here. Instead, we attempt to draw some supplementary effects of Cp2-induced changes on the carbonate saturation state of tropical oceans, and hence on conclusions based on the nature of the specific recom­ calcifying communities, has not been the subject of any mendations and the general ambience of the workshop. significant research; although the possible significance Contrary to what might have been expected of this predictable chemical change is obvious, its beforehand, the workshop participants strongly and actual ecological effect is unknown (Smith). unanimously recommended development of a global­ Temperature is potentially the most significant scale, coordinated program of coral reef monitoring. It long-term climatic stressor. Mearns presented a variety was made abundantly clear that the vision was a of GCM results of sea surface temperatures in reef recognition that research on global problems can be areas; the results consistently suggested an increase in effective only when supported by scientifically-based

9 data collection on time and space scales relevant to the Bleaching is one symptom of increased environ­ questions being addressed. This outcome not only mental stress; its frequency of occurrence has appar­ challenges the traditionally perceived "monitoring vs. ently increased in some areas, with some but not all of research" conflict in the U.S. science establishment, but the events attributable to local high temperatures. also challenges U.S. agencies and institutions to Bleaching merits serious study as an indicator of coral participate in the development of more effective stress and environmental quality; however, on the international ties than now exist. basis of present understanding, definitions, and Recommendations by both working groups environmental records, there is no credible theoretical strongly endorsed expanded research on the use of the or empirical basis for the claim that bleaching is or can environmental signals extractable from coral skeletal be used as a reliable indicator of global climate growth chronologies to extend retrospectively our change. baseline data on change, variability, and biological Anthropogenic environmental alterations on responses in coral reef environments. Paleoclimate global, regional, and local levels are reason for serious studies have traditionally co-existed uneasily with concern about the health and local survival of coral modeling and empirical observations in the terrestrial reef ecosystems. Now and in the near future, concerns environment, where instrumental and historical about the direct effects of the human population records are of longer duration. In shallow tropical explosion, resource exploitation, and development marine environments, however, the length and geo­ outweigh the longer-term threat of climate change, but graphic extent of direct observations are clearly inad­ an appropriate research and monitoring program will equate for present needs, and the high temporal identify and address problems stemming from envi­ resolution and variety of environmental signals inher­ ronmental change regardless of its ultimate cause. ent in coral skeletons suggest that the use of retrospec­ Recommendations for scientific action include tive environmental proxies may make major contribu­ prompt development of a research-oriented coral reef tions to our understanding of these environments and monitoring program of global scale, a coordinated ecosystems. program of research at laboratory, microcosm, and Research activities are recommended at all scales field scales, and continued interdisciplinary review -laboratory, microcosm, and field.limplicit in these and coordination of research needs and opportunities recommendations is the need for a more coordinated, in the area of overlap between coral reef studies and interdisciplinary and collaborative approach to reef larger environmental and geoscience issues. Specific studies than has been the case in the past. Just as research topics and priorities are presented in the disciplines such as oceanography, astronomy, and reports of the working groups. physics have recognized that the necessary tools and approaches can be supported only on a communal Acknowledgments basis, needs such as for sophisticated microcosm facilities that are beyond the reach of individual The organizers acknowledge Mary Griffin, Bill investigators and for data comparability between Kiene and Daphne Fautin for their untiring help and . individual studies seem likely to force coral reef unfailing equanimity, and we thank Amy Broussard of scientists, institutions, and supporting agencies to Texas Sea Grant for making time in her busy schedule reappraise the social and economic framework of to help with communications efforts. research design and support This institutional require­ ment for collaborative, interdisciplinary, and coordi­ nated research offers special challenges that have never before been faced by the coral reef research commu­ nity. Workshop Conclusions The primary conclusion that reflects the senti­ ments of workshop participants and is currently based, out of necessity, on diverse observations and anecdotal information is as follows: on a global average basis, coral reefs are being lost or degraded at an alarming rate. If true, this is potentially serious because of their biotic and economic importance, but at present we lack the data needed to confirm, quantify, or explain this trend on a scientific basis.

10 4. potential to compare closely related species CLIMATE WORK GROUP or populations from major reef systems and more extreme sites Sub-Group 1: Reef Response to Change 5. transects across tum-on/turn-off regional Facilitator: Don Kinsey. Participants: Bruce Chalker, gradients Joe Connell, William Davis, Gary Hendrix, Nancy Knowlton, Yosi Loya, Claes Rooth, Malcolm Shick B. Specific Criteria LWHYREEFS? 1. previous history of study Reefs are but one of many ecosystems threat­ 2. logistical support ened by short and long term effects of man's activi­ 3. interest to the United States ties. Nevertheless, reefs have special features which justify intensive and immediate study: C. Suggestions (• U.S. waters or government laboratories) I A. Generr Importance to the World 1. Major reef sites 1. protection of coastlines- property and lives a. Caribbean: island (•US.V.I., •Puerto 2. tourism -recreation for participants and Rico) continental (•Panama, •Belize) economy b. Central-West Pacific: high island 3. food -commercial and subsistence (•Guam, Moorea/Tahiti) atoll I, 4. biodiversity- intrinsic value and natural (•Enewetak, Tuamotos) products c. Central Great Barrier Reef: inshore, I 5. established ecosystem - intrinsic value as offshore for tainforests d. Southeast Asian fringing reefs 6 scie~tific understanding (e.g., paleoclimates, 2. Reef sites in extreme or isolated environ- functioning of complex ecosystems) ments I 7. environmental indicators- potentially a. •Florida Keys (including Dry Tortugas) definable responses to environmental stress b. •Hawaii I B. Specific Importance to the U.S. c. •Gulf of Mexico (Flower Gardens) 1. substantial areas of reef in U.S. territorial d. •Eastern Pacific (upwelling and not waters (Florida, Hawaii, Puerto Rico, U.S. upwelling) Virgin Islands, US. Trust territories) e. Bermuda 2. enormous importance of reefs to developing f. Eilat natipns in our hemisphere (e.g., Caribbean g. Heron Island Basin Initiative) h. Okinawa D. WHIOI REEFS? i. Western Australia (e.g. Abrolhos as latitudinal extreme) Which reefs should be studied is a necessary compromise between the desire to have broad j. Lord Howe Island (latitudinal extreme) geographic coverage and the need for detailed informatibn. We propose areas of specific interest III. COMPLEXITY OF THE PROBLEM based on the following general objectives and Understanding the impact of environmental specific crteria: change on coral reefs is an enormous problem A. General Objectives because of the number of potential factors to be considered (including interactions between them) 1. broJd geographic coverage and the need to study numerous sites and numerous 2. maormation. " I . on maJOr• reef systems w1t . h species within these sites. Interactions are critical comparisons within them across important because the effects of two or more factors are often environmental gradients not additive. The dramatic response of chronically stressed but superficially normal reefs to an acute 3. reefs in extreme habitats of particular interest stress is a particularly important example of this in the context of local and global environ­ phenomenon. Multiple sites and species are critical mental change because different communities may have different

11 responses and even the same species at different sites tropical environments are critically important but may have different responses because of the effects of poorly understood. This is a problem of Modelling past evolutionary selection. coupled with testing through continued Monitoring We list the primary anthropogenic factors, plus of physical parameters. a limited set of interactions among them. For each B. Information on Past Conditions and factor, we indicate the pattern of expected change. Communities Experimental treatments need to reflect as best as possible the relevant time scales of the expected This is critical because we need to distinguish changes (e.g., pulse perturbation, press manipula­ potential changes which may have been experienced tions with gradual or sudden onsets). Many more by reefs in the not too distant past from those which and more complex interactions than those listed are have never been experienced. As with the above, expected, but constraints on replication and statisti­ both means, variances and rates of change need to be cal analysis require focus on a limited number of at considered. It would be predicted that changes most three-way interactions. previously experienced and survived pose less of a threat. However, since some of the changes are A. Factors (in Isolation) certainly novel, one cannot assume that a previously 1. Temperature (changing mean and variance) survived condition will be equally manageable when combined with novel stresses. This is a problem of 2. Sea Level (changing mean) detailed Paleontological Observations (sec climate 3. Sedimentation (changing mean and variance) group 2 report, below). 4. Wave Energy (changing mean and variance) C. Basic Information on the Nature and 5. col (changing mean) Mechanisms of Biological Interactions 6. U.V. and visible radiation (changing mean) Many aspects of normal reef functioning arc 7. nutrients (changing mean and variance) poorly understood, making it difficult to predict the 8. overfishing (changing mean) effects of man's activities. A particularly important example is the role of disease on reefs. Field and 9. toxic pollutants (changing mean, variance Laboratory Experimentation (including microcosms) perhaps) and complex Computer Simulations are all valuable 10. fresh water (changing variance) approaches to this basic problem. B. Interactions of Special Importance D. Systematics 1. temperature + light+ nutrients Even the best studied of reef organisms arc not 2. temperature + nutrients+ biological interac­ well categorized systematically, with even model tions taxa containing unrecognized sibling species. Also, for many region, no adequate manuals for the 3. temperature+ light + pollutants identification of even the corals exists. This problem 4. storms+ nutrients (study where opportunis­ could be solved by an investment in Systematic tically possible) Studies followed by publication of Manuals with keys and illustrations usable by all reef workers. IV. BACKGROUND INFORMATION REQUIRED FOR PLANNING STUDIES V. GENERAL EXPERIMENTAL PROTOCOL Planning studies of the effects of environmental If we are to understand the effects of environ­ change on reefs requires two important sets of mental change on reefs, we must attack the problem background information. Of particular importance at a variety of hierarchical levels. Most central is the are: individual, which is the unit of birth and death. In some cases we may need specific information on the A. Projections for Future Climate Change physiology and cell biology of the response, particu­ Our experiments are necessarily designed to larly to clarify future research directions. Moving up reflect likely changes. Realistically, we should the hierarchy, interactions between individuals will concentrate on likely changes within the next decade eventually translate into a community response. to century. We need information both on magnitude Different hierarchies demand different methods. In and rates of projected mean change, but in some general, we recommend the following approaches, cases changes in variance are even more important. listed without implication of priority: We have general predictions from modelers but in A. Cell Biology- Laboratory Experiments particular feel that temperature effects in nearshore

12 B. Physiology-Laboratory Experiments studies aimed at detecting evolutionary responses to different environmental re­ C. Individual growth, reproduction, mortality­ gimes) laboratory or microcosm experiments (depending 3. Ecologically key species on scale) field monitoring 4. ''Lab rats" for physiological and cell biologi­ D. Community Structure -Microcosms (Especially cal studies. for Competition, e.g., Algae vs. Corals) 5. Species of great paleontological importance Theoretical Modelling Field Monitoring and Field Experiments B. Other important species Laboratory experiments have a long tradition 1. Representatives of major morphological and the methodologies are well established. Theoreti­ strategies in corals(branching, massive, and cal modelling requires access to advanced computers weedy) and programming expertise which are available but 2. Important competitors of corals (especially scarce resources. Field monitoring requires good algae) management and support for manpower, into the 3. Important predators of corals and algal indefinite future. Field monitoring also requires good grazers designs based upon maximizing statistical power (e.g., sufficient power, randomized plots, etc.). VII. PRIORITIES FOR THE NEXT FIVE YEARS Properly designed observations can test hypotheses (UNRANKED) and are in some cases the only alternative because of the large seale of the processes involved. Microcosms A. Experiments to determine the response of model have been! underutilized because of the capital system species to the effects of radiation and expense, especially with adequate replication. These temperature are the m~thod of choice for a number of critical These studies will involve both laboratory and experimertts. Marine facilities are currently very field manipulations. Radiation (via changes in limited but the technology exists and several such cloudiness, turbidity, and ozone) and temperature facilities should be a top priority. (via the green house effect) are the most important I VI. SPECIES TO BE STUDIED Long-term changes expected as a function of anthro­ pogenic modifications to the environment. The species to be studied at the cell, organismal and community levels will vary depending on the B. Establishment of a world-wide monitoring questions asked. Not everything can be studied. system of physical and biological parameters on Some species will be intensively studied at all levels reefs because of their importance as model systems. A Changes can only be detected if we begin a limited number of other species of considerable sophisticated and well managed program now. Field importance in reef communities will be studied in experiments relevant to the problem of global change less detail (e.g., tests for sensitivity to temperature should be coordinated with this monitoring network. and U.V.). We recommend that the systematic status of all model system species be clarified as soon as C. Development of microcosm facilities for possible to facilitate interpretation and comparison of bridging the laboratory to field spectrum. results. Nutrients in particular are difficult to manipu­ We make the following suggestions of criteria late in the field at a scale required to study commu­ ~wo for these categories of subject species. For model nity level effects, arc one of the most important systems, the more criteria which can be satisfied, the Short-term consequences of human activity and better, sinte only a limited number of model systems population growth. are feasible. D. Increased use and development of complex A. Model systems model simulations both for physical effects in 1. Indicator species (species with special nearshore tropical environments and biological sensitivity to changes in temperature, interactions in high diversity reef communities. nutrients, toxic pollutants, U.V., etc.) E. Where needed, publication of well illustrated 2. Species with broad geographic ranges (these manuals with workable keys permitting reef may be species complexes but nevertheless scientists and technicians to identify major taxa, have enormous potential for comparative particularly for regions to be intensively studied.

13 This should be backed up by systematic research Due to increased activities of man, although where necessary. perhaps some upwelling changes. Proposed research: monitoring (water quality, remote sensing, commu­ Vlll. EXPERIMENTAL PROTOCOLS-DETAILS nity changes), microcosm experiments to look at FORSPE~CFACTORS competition between coral and algae, where possible (enclosed lagoons and tidal flats) manipulations in Our choice of experimental designs reflects the consensus that both the long-term effects of climate the field. change and the short-term effects of human activity H. C02 and population growth need to be investigated. Predicted gradual increase. Proposed research: A. Sea Level Rise tropics not likely to differ from other already moni­ tored sites. Laboratory and microcosm experiments Of little effect at least over the short term, except to determine effects on algae, zooxanthellae (free) on reef flats where negative effects of extreme low and corals. tides may be mitigated. B. Temperature · I. Toxic and Artificial Substances Over the short term, increased variability likely Already present due to man's activities and may continue to increase. Proposed research: Monitoring to be more important than gradual mean increase. Proposed research: monitoring (including compari­ and laboratory sensitivity studies. sons of sites with different temperature regimes), J. Overfishing and Related Activities transplants within regions between sites of different temperature regimes (e.g., within Red Sea or within Biological interactions have been and are being Eastern Pacific), laboratory tests of temperature modified by activities which change the relative sensitivities (both to variation and mean increase). abundance of reef organisms. Proposed research: Monitoring abundance and distribution of reef C. Ocean Currents and Wave Climate organisms at all trophic levels, field manipulations of important predators, competitors, grazers, symbionts No major trends expected over the next decade and bioeroders on reefs. Microcosms and complex D. Storms computer simulations of interactions. No major effects over the short term, although Overall, we feel the following factors are in most increased storm effects predicted in context of mean urgent need of investigation: temperature, light, temperature increase. Proposed research: monitoring nutrients, and biological interactions (especially of recovery on fine spatial scales in monitored sites algae, corallivores, and grazers). experiencing storm damage. Computer simulations are important because experimental simulation Sub-Group 2: History of Environmental and usually impossible. Ecological Variability from Coral Reefs E. Radiation (U.V. and visible) Participants: Julia Cole, Margaret Delaney, Bob Halley, David Hopley, Paul Ringold Predicted effects are an increase in U.V. via ozone depletion, plus changes in visible light due to changes in cloud patterns and turbidity of water. I. INTRODUCTION Proposed research: urgent need to establish monitor­ Coral reefs have obviously survived past ing network in tropics using scanning environmental changes on global to local scales. The spectroradiometer (290-750) at depths from surface to nature of these changes and the associated reef 5% visible light. Laboratory experiments using both responses are preserved in records from modem and acute and gradual exposures. fossil reefs. These records represent outstanding F. Sedimentation and Turbidity opportunities for defining the relationship between natural environmental variability and reef response Will be influenced by a variety of climate on time scales ranging from seasonal to thousands of changes (e.g., rainfall, storms, etc.). Proposed re­ years. Coral records also provide histories of anthro­ search: monitoring (in situ and remote sensing), lab pogenic impacts on reefs in recent decades. Im­ and microcosm studies and field experil)lents proved understanding of past reef variability will including transplants. provide a strong foundation for the anticipation and G. Nutrients recognition of future environmental impacts on reefs.

14 A. Contributions from the Paleoenvironmental cores and outcrops for changes in zonation and Records of Reefs community structure during sea level rise, global warming, and other changes in physical and environ­ Cores of long-lived individual coral heads have mental parameters. the potential to delineate the range of natural climate variability in tropical reef environments over the last These studies should delineate reef community several centuries. Longer cores through reefs encoun­ perturbations on the scale of hundreds of years that ter massive corals that provide windows of high­ must be understood to put present-day observations resolution record throughout the Holocene and late in a long-term perspective. Pleistocene. Many skeletal parameters can be applied C. Rates of Climate Change and Coral Response to reconstruct independent aspects of reef environ­ mental variability at annual to subseasonal resolu­ Future climate change will include changes in tion; these are detailed in Table 1. mean conditions, variability, and the frequency of The length of continuous chronologies is limited extreme events. Records from coral reefs will help by the age of the coral and can extend to several define variability and shifts in mean states of past centuries. Older discontinuou~ chronologies are climates in the regions of the reefs themselves. possible throughout the Holocene and late Pleisto­ Anticipating the response of reefs to future climate cene, with absolute dating provided by radiometric change rests in part on identifying thresholds in methods. Over timescales of centuries to millennia, absolute values and rates of change beyond which the presence of shallow dwelling fossil corals has reef organisms cannot survive. provided the basis for sea level estimates throughout D. Monitoring, Calibration and Quality Control the Quaternary. These coral records can address times of i.pportant global climate change during the Many aspects of the paleoenvironmental record past seve~) thousand years. Such reconstructions would benefit from further calibration by laboratory will greatly improve our understanding of the and field studies. There is a particular need for sensidvilj of tropical environments to large-scale seawater analyses of components significant in the climate forcing on a range of time scales. coral paleoclimatic record such as stable isotopes and trace metals. Existing collections of reef material Time periods that should yield useful insights should be analyzed to derive maximum benefit from include ti~es thought to be generally warmer (the Medieval •Warm Period, the mid-Holocene Climatic minimal destructive sampling. Optimum) as well as times of large scale global E. Summary climate change of (e.g., the Little Ice Age, the Younger Dryas and the last deglaciation). Refining the techniques discussed in this report and demonstrating their usefulness will be shown by High-resolution records spanning the past targeting coring programs in areas of well-docu­ several centuries will document the range of past mented perturbations through which at least conti­ natural climate variability over time scales more nuity of coral growth has occurred. relevant to the human experience. A detectable Paleoenvironmental studies on reefs represent record of bleaching events may be incorporated into retroactive monitoring programs that can produce the coral skeleton, via chemical or growth rate results over long time spans at resolutions compa­ perturbations. The pursuit of this record should be a rable to those achievable in the modem record, for a priority, as should the development of new indica­ comparatively small investment of time and re­ tors for other reef processes and perturbations. sources. More specific research recommendations are B. Ecological and Paleoecological Studies outlined in the section on skeletal tracers of coral bleaching (sec below). Rccflgrowth and change on the scale of centu­ ries to mi,lennia can be addressed using classic paleoecological techniques including description of Sub Group 3: Data Required by Researchers community structure, function, and composition. Taphonomic studies of modem reefs in crisis will Participants: George Dennis, Mark Eakin, Pamela more clearly define interpretations from these Hallock-Muller, George Maul, Linda Mearns, Gene geologic records of reef growth. Corals growing ncar Rasmussen, Charles Yentsch the limits of their environmental tolerances may show particular sensitivity to past and future envi­ I. ISSUES ronmental change. Existing reef cores have provided histories of reef sedimentation during the Holocene. A. What is the role of climate models in the These cores should be reexamined along with new investigation of environmental effects on reefs?

15 Resuspension, lndicatod.Processes Upwelling, Anthropogenic Terrestrial Environmental Jediment diagenesis, SST Salinity nutrients inpUIS ENSO runoff Rainfall Light Produclivity stress volcanic inpllll 1801160 ++ ++ ++ + 13CI12C + + + + + Bomb mdionuclides + ++

Growth raiCS, hialusel + + + + + ++ Band density + + + UV fluOJaeence ++ Ba + + ++ + + Sr + + Cd + ++ + + Ma + + + Pb ++ Gcomec:bani.cs + + Crystallography + +

Table 1. The potential use ofvarious indicators to identify changes in environmental proceiSCS.

Tbc application of these indicators to dcfiJiing variali.ons in these processea can be site specific 81 presenL

(++)indicates SUODg signals with lalowu wide geographic applicability

(+)indicates signal strongly corrdatccl with processc1 al some shes, with strong events at many silel, or rcqiring further dcvelopmcnL Which parameters can be estimated? What scales scales relevant to these systems. Development of are important to reefs? What can reef researchers LAM/GCMs for coastal areas should be investigated. provide to modelers? Such a modeling system for eastern Australia is being developed by Macquarie University in coop­ At the present state of the art of atmospheric eration with NCAR (National Center for Atmo­ general circulation models coupled to ocean general spheric Research). circulation models (AGCMs/OGCMs) or as the art will develop in the near future (e.g., within the next For specific case studies, calculations from several years) the following climate variables and operational models, such as the ECMWF (European estimates of how they would change under transient Centre for Medium Range Weather Forecasting), cq increase scenarios could be provided on at least should be used to provide boundary conditions for daily time scales (and/or daily maximum/ minimum LAMs. Within the LAM area, even higher spatial and values) at relevant selected locations. These variables temporal resolution data should be used in diagnos­ are those, deemed most important for determining tic mode to improve understanding of the processes climate effects on coral reef ecosystems: involved that affect coral reef communities. This approach is recommended as part of the design • Sea Surface temperatures, ocean temperatures experiment for a monitoring network. It is antici­ to 100-m depth pated that site-specific monitoring networks will be • Wind speed and direction required, and we should be prepared to be very • Salinity flexible in this regard . • Absorbed solar radiation at the surface B. How can we distinguish direct anthropogenic • Barometric pressure signals &om global climate-change signals? • NeJ.-surface air temperatures As a result of ever-growing human populations, I • Ncar-surface vapor pressure anthropogenically induced environmental perturba­ tions are occurring worldwide. Effects range from • Regtonal rainfall and runoff (for determina­ local physical damage (e.g., destructive fishing, tion bf sediment loads related to coastal reefs) I recreation and construction activities) to global • Sea level changes climate change as the result of atmospheric buildup The~rototypical AGCM which is or will be of cq and other greenhouse gases in the atmo­ available for providing these variables will have the sphere. 1 following characteristics: horizontal resolution of 2.5° Two types of pollution that have tremendous x 2.5°, with a minimum of 12 vertical layers, coupled potential for altering ecosystems worldwide are to a full OGCM with to x to horizontal resolution and anthropogenic enhancements of totally natural and 20 vertical layers. essential chemicals: Cqand nutrients. Humans have 0 Currently, the coarse resolution (e.g., so X S ) severely altered the distribution of these chemicals in models dm provide these variables but due to the the environment almost certainly causing stress in complex bumate interactions in the tropics, higher many reef environments. resolutio~ models would be particularly desirable. A major challenge to scientists studying reef Current models do not in general perform well in the communities is to distinguish the effects of different tropics. I~ the future, finer scale resolution in space classes of perturbations, particularly natural climatic and timelwill provide projections at a level more variability as compared to anthropogenically­ meaning(ul to coral ecosystems. induced changes. Responses at the organism and The ~hopefully) detailed climate change sce­ community levels reflect all environmental factors. narios will help indicate future environmental Therefore distinguishing among, e.g., the effects of stresses tp which the ecosystems may be subjected. temperature, increased ultraviolet radiation, or Therefore, it is possible that detailed analysis of nutrient enrichment, will be very difficult and will relevant tlimate variables will aid in guiding bioas­ require carefully designed and controlled experimen­ says of cdrals, such as determining levels of thermal tation and diagnostic numerical modelling (LAMS). stress fori tolerance experiments Such work should be a priority ofrecfresearchers. Additionally, the monitoring system to be To separate global-scale community effects, established for coral reef ecosystems could help to such as warming or increased U.V. from local or validate the climate models, especially finer resolu­ regional anthropogenic effects such as nutrient tion limited area models (LAM) nested within the pollution, reef communities must be monitored to coarser resolution GCMs. The LAM/GCM will be of make interregional comparisons. We must keep in particular use in coral reef studies due to the finer mind that regional anthropogenic effects are more

17 prevalent in regions of continental influence such as • Salinity, temperature, water transparency, the Caribbean/Gulf of Mexico and the Indo-western radiation, sediment load and turbidity Pacific, while the effects of global change may be the • Bottom topography major anthropogenic influence on isolated reefs of the tropical Pacific. This might be accomplished by forming a network of permanent stations at two levels. Level C. What are the monitoring requirements of reefs one would comprise combined research and moni­ and physical parameters? toring stations conducting standard monitoring, calibration of monitoring activities and sophisticated In the last decades there have been reports of monitoring of physiological responses. Some five widespread deterioration in vast areas of coral reef facilities capable of carrying out such a program ecosystems. These were attributed to the spread of already exist or could be formed by relatively Acanthaster planci, bleaching events, direct destruc­ minimal upgrades. These require full scientific staff tion due to various human activities and global, as well as adequate instrumentation, and should be climate-change related phenomena. Without an funded as research programs leading to the develop­ integrated and comprehensive program, it will be ment of uniform protocols and integrated databases impossible to provide a balanced scientific assess­ over the first 3-5 years. ment of future trends in coral reefs, nor to suggest any local or international course of action, if deemed At least twenty additional monitoring-only necessary and feasible. stations (level two) would supplement the level one stations. These might be operated by semi-skilled To diagnose the causes of ecological stress­ personnel equipped with robust, nearly mainte­ events on coral reefs, a program of Synoptic Environ­ nance-free tools. These should be funded as perma­ mental Assessment (SEA) is needed to monitor and nent environmental monitoring facilities, feeding analyze the physical and biological observations into a worldwide "coral watch" database. needed on relevant temporal and spatial scales. The following is a list of critical observations to be It will be difficult to interpret these local obser­ included in such a program. vations in the context of the large scale fields re­ solved by current GCM's. The output of those Near Surface Physical: models can define the scale of pelagic variables • Atmospheric temperature (temperature, salinity, etc.) but proper interpreta­ • Spectral irradiance tions of the observations in the neighborhood of the reef requires a nested numerical modelling approach. • Barometric pressure We believe that the Marine Ecosystem Analysis • Wind speed and direction (MESA) program can serve as a model for this • Rainfall observation/diagnostic approach. A mixture of physical measurements and diagnostic numerical • Humidity modeling was used in that program to define fields Sedimentological: of variables pertinent to ecological stress. • Composition In summary, a parallel theoretical/observational • Organic content approach is proposed whereby the cause and effect • Grain-size composition relationships can be quantified at carefully selected sites and then applied to the generic problem. We Water column, biological: recommend that a meeting be held specifically to • Phytoplankton (chlorophyll) concentration address the design of the monitoring program and • Zooplankton concentration distribution of monitoring stations. Ocean observations: D. What historical data are available for • Sea surface temperature correlation? • Sea level (incl. vertical geodetic stability) 1. Historical data from colonial records, ship • Current speed and direction records, older aerial photographs, etc. • Wave energy 2. Data sets that are not specific to reefs that are potentially useful to reef researchers: • Nutrient levels (incl. nitrogen, phosphorus, total inorganic carbon and iron) Institutional: Profiles of: •NOS (National Ocean Service) •NCDC (National Climatic Data Center)

18 •NODC (National Oceanographic Data Center) protected coastlines to higher wave energy regimes •World Data Center A (Washington) and B within a few decades. (Moscow), Protection of coral reefs as unique and intrinsi­ Data sets: cally valuable resources in their own right.is an ethical position which is being taken by this group. •Comprehensive Ocean-Atmosphere Data Set (COADS) n. THE NEED FOR REMOTE SENSING OF •ISCCP (International Satellite Ooud CORAL REEFS Climatologic Project - high resolution cloud data set a decade in length) Coral reefs are ideal candidates for remote sensing, especially those techniques which employ •CZCS, AVHRR and other sea surface satellite optical sensors about environmental effects of Global datal I Climatic Change. We must now begin to plan how to Otl\er sources: develop technology and research strategies for I •Military data sets assessment of coral reef biomass and measurement of growth levels using these optical sensors. • Pri~tely held data (oil companies, fishing com}>anies (Japan), shipping companies, etc.) Crucial to this is the state of the art of optical remote sensing using active (LIDAR) or passive A significant effort could be funded to obtain, (wavelength scanners) instrumentation. Both systems digitize, ~nd distribute these data. have been used to study the characteristics of vegeta­ 3. Paleoclimatological records from terrestrial tion. Both have limitations as to areal coverage and/ and deep sea sources (published records). or detection specificity. Present scanners have a 4. Trllnsects and field sampling sites in reef spatial resolution of 40-1000 meters. LIDAR probes en ironments sampled a decade+ ago. have approximately one meter resolution based (R surveys of these sites should be a priority largely on aircraft altitude. beJause of their potential to identify changes The capabilities of optical remote sensing are and possible trends in populations and outlined in Table 2. LIDAR should be able to mea­ communities.) sure the fluorescence of chlorophyll Fchi' phyco­ erythrin Fpe~ phycocyanin Fpc' and the blue green E. What ~alue can we place on reefs to reinforce the fluorescence F"s characteristic of most corals. Sun­ research efforts being generated? induced fluorescence of zooxanthellae also could be ThJ Joss and degradation of reef habitat has measured. importattt economic implications, particularly for Reflectance (spectral) through radiometry island n~tions. Healthy reefs are major tourism would allow measurement of chlorophyll as well as resourc~, with revenue from vacationers, divers, water clarity. Reflectance from a pulsed laser at the recreatidnal fishing, and others. Reef and associated appropriate wavelengths can be used for measure­ seagrassi and man~ove communities pr~vide. ment of chlorophyll and water clarity. nurseries and habitat for many commeraally Impor­ Coral photosynthesis can be estimated using tant spec:ies such as lobster and shrimp, and is a chlorophyll light (incoming) and water clarity. major source of subsistence protein in many island A taxonomy through the detection of different color nations. Coral reefs and associated communities ~ouqs can be used to tdentt6{ the al~ in.c::ntal. ~( support exceptiona\\y diverse accumu'\anons o\ \axa; communities. Correlations of fluorescence with the potehtiai of these taxa for providing biochemicals reflectance signals ~ltllclt/ would provide a measure of of medi~l and industrial value is just being realized. photosynthetic efficiency. A study of the fluorescence The harJest of reef resources, including fisheries, signals from chlorophyll and accessory pigments biochemlcalsources, and even sediments for build­ could be used as a diagnostic to measure algal ing mahhials must be carefully managed as renew­ invasion after a bleaching event. able resdurces for sustainable yields. Co~l reefs provide natural breakwaters for Although satellite remote sensing techniques are coastlines and harbors and will become increasingly useful to monitor changes in many large ecological important for storm protection as sea level rises. A systems, the resolution of these data is such that healthy reef should keep pace with the anticipated current remote sensing of coral reefs should be rate of sea level rise, while a dead or damaged reef directed at high resolution airborne systems and can degrade at rates up to 5-10 times higher than the associated ground truthing. These have the ability to accretion rates of healthy reefs. Thus, even without produce pixel sizes equivalent to the scale of coral sea level rise, loss of reefs will subject currently colonies. Of particular use will be the definition of

19 spectral signatures over wavelengths ranging from U.V. through visible to at least the near-IR. Data CORAL BLEACHING WORK GROUP already at hand indicate that in near-IR wavelengths small variations in spectral signatures may be Facilitator: Jeremy Jackson. Participants: Terry Done, identified among different species of corals. Signa­ Zvy Dubinsky, Robert Dunbar, Joe Elms, David Enfield, tures certainly change as corals undergo stress. Peter Glynn, Paul Jokiel, Michael Lesser, Leonard Expansion of this type of work will allow researchers Muscatine, Caroline Rogers. Robert Rowan, Deborah to gather data at scales needed to discern regional to Santavy, Glen Shen, Gerard Wellington, Robert Wicklund, global scale changes in coral reef ecosystems. WU/iam Wiebe, Ernest Williams Complementing these optical (visible) wave­ Bleaching is a symptom of the expulsion of length observations will be reflected IR and emitted symbiotic algae by corals and other reef animals in IR. Reflected IR will provide high definition of land - response to environmental stress. There is a percep­ sea boundaries, and assist in the quantification of tion that bleaching of reef corals may be a preview of areal mapping. Emitted IR, particularly multispectral future effects of global warming. sensing, will provide SST information at the scale of There are three general aspects of coral reef interest to the local patchiness that may be typical of bleaching: the SST on coral reefs. Here again, aircraft observa­ • The nature of the evidence for coral reef tions will probably provide data at the scale required, bleaching and its association to environmental and with Jess atmospheric influence form the lower variation. altitudes, the higher accuracy required. • Possible mechanisms and consequences of Other remote sensing should also be kept in bleaching for reef corals and other symbiotic mind. HF coastal radar has been shown to provide animals. high resolution maps of sea surface current vectors at 1-2 km spatial resolution and at 3-hour time steps; • Possible long-term consequences of coral reef typically 100 square kilometers of coverage from two bleaching. HF stations is possible. Synthetic Aperture Radar I. THE NATURE OF THE BLEAODNG (SAR) or Side-Looking Airborne Radar (SLAR) can PHENOMENON also provide important information on currents and internal waves that may be affecting the circulation A. Specific Questions Addressed: around coral reefs; both SLAR and SAR can be obtained from aircraft, but SAR at 25:-meter pixel 1. Is coral reef bleaching an important source of resolution is available from satellite. Finally, coral mortality, and is it increasing? scatterometer data from either aircraft or satellite can Intensive underwater observations on coral provide detailed information on the wind stress reefs began in the late 1950s in the Caribbean and the vector in and around coral reefs, and this will be 1960s elsewhere. Since then, coral reef bleaching and most valuable in data assimilation modeling of the associated death of reef corals has occurred more currents and wave energy that may be affecting a frequently and on a larger scale within the past ten particular reef. years. This is especially true in the eastern and central Pacific during the 1982-83 El Nino event, and in the Caribbean from the late 1980s to present. Table 2. Capabilities of Optical Remote Sensing. Bleaching in the western Pacific has been more sporadic. There is also paleoecological evidence that REMOTE METHODS extreme bleaching and mass mortality comparable to the 1982-83 event had not occurred in the eastern A. Fluorescence LIDAR Fchl. Fpe. Fpc. Fbg Pacific during the previous approximately 300 years. Sun Induced Fchl There are no comparable data from elsewhere. B. Reflectance Radiometry chi. clarity 2. What is the evidence that bleaching is caused Laser chi. clarity by high temperature or by other factors? In SCIENTIFIC USES this regard, is bleaching an indicator of climate change? 1. Photosynthesis chi. clarity 2. Ataxonomy Fchl. Fpe. Fpc. Fbg There is strong evidence, particularly from the 3. Physiological Status Fchl/chl. FchVpe. FchVpc central and eastern Pacific, that widespread bleach­ ing is associated with unusual increases in tempera­ ture. Laboratory experiments demonstrate that high temperatures can induce bleaching in a manner

20 consistent with field observations. However, there local warming trends, or any other factors affecting remains serious question about the closeness and the general health of coral reefs, emphasizes the need universality of the association of bleaching with high for sustained field ecological research by interdisci­ seawater temperatures, and the likely role of other plinary teams and the immediate need for an institu­ factors that may cause bleaching on local and re­ tionally supported coral reef ecosystems monitoring gional scales. effort. The scale of this effort with regard to coral Numerous workers have shown that loss of bleaching should be appropriate to the questions of · zooxanthellae occurs during excessive sea water the link between global warming and elevated warming under both laboratory and field conditions. temperature and the link between temperature and Bleaching typically occurs when water temperatures coral bleaching. Other scales may be appropriate for rise only 2-30C above ambient over a period of some assessment of other potential anthropogenic effects 3-5 wee*. Slightly higher water temperatures can on reef ecosystems. induce bleaching over shorter time intervals. Bleach­ C. Research Priorities ing can afso result from factors such as low tempera­ ture, reduced salinity, high sedimentation, and 1. Establishment of a Global, Long-term anthropdgenic effects, but most recent events of Research and Monitoring Network to Follow concern have been associated with high temperature Climate Change and Anthropogenic Input stress. i Effects on Coral Reefs. Widespread bleaching and mortality of reef­ It is the unanimous opinion of workshop building brats on a large scale were first reported participants that sustained ecological monitoring at during t~e 1982-83 El Nino. Bleaching also extended several sites is an absolutely essential component of westwar~ to Indonesia and Australia during the ecological research on coral reefs. Long-term data are 1982-83 ENSO. Sea warming was also implicated in crucial to the interpretation of short-term ecological a series of major bleaching events during 1987 in the experiments, regional or global occurrences of coral Caribbeah. In 1990, severe coral reef bleaching bleaching, and possible global climate change. occurred Ithroughout the tropical and subtropical Such data can only be gathered through a western Atlantic region, and in 1991 severe bleaching network of extensive and intensive permanent also occtftred in French Polynesia. monitoring stations where identical instrumentation In most cases, abnormally high sea temperature and standardized procedures are used. The monitor­ was assodated with the bleaching, although other ing of biological parameters should be non-destruc­ factors s4ch as irradiance, altered salinity, altered tive, allowing for prolonged observation of particular oxygen cbncentration, and human induced changes localities and even individual coral colonies. Strate­ may also: be involved. Although the relationship gically distributed stations would combine research between high temperature and bleaching is incontro­ and monitoring functions, in addition to calibration vertible •tmany instances, data are insufficient in activities, sophisticated monitoring of physiological some do · mented bleaching events to confirm this processes, and technical staff training. relations ip unequivocally. There is no clear evi­ Five to ten facilities capable of conducting such dence fot the coupling of coral reef bleaching and be w~rming a program either exist already or could created by global because of the lack of relevant data. relatively minimal up-grading. These intensive 3. Asi~e from bleaching, are coral reefs in stations require full scientific staff, adequate instru­ gerieral decline? If so, what are the major mentation, and funding for a period sufficient to fact6rs apparently responsible? develop protocols and integrated databases. Twenty MoJt participants believe that coral reefs are additional, extensive, monitoring-only stations serioustyjendangered in many areas, but that few would supplement these. Such stations would be quantitative data are available to sustain or reject this operated by trained field technicians equipped with perceptidn. Fringing reefs in areas of intensively robust, nearly maintenance-free tools. These should increasing agriculture, deforestation, and urban be funded as permanent environmental monitoring development may be particularly threatened. facilities, the function of which would be to feed data into a worldwide database. B. Summary a. Choice of sites The correlation of elevated sea water tempera­ • Extensive: in carefully selected coral ture and coral bleaching is compelling. Elevated reefs representing diverse conditions I • temperature as a consequence of a putative global and various disturbance levels. warming trend is not yet established. The glaring • Intensive: existing marine labs or MAB lack of a retrospective field data base on global and sites.

21 b. Spatial scales require chemical or isotopic analyses. However, in • Large scale- using satellites, LIDAR the context of assessing regional and global"health" aircraft, oceanographic vessels, GIS, etc. of coral reef systems, the identification of all wide­ spread stress events in the skeletal record should be • Community -physical parameters of interest, regardless of whether they can or cannot (temperature, salihity, tide, etc.), com­ be clearly linked to coral bleaching. munity structure (by means of biotic surveys, etc.), community physiology, Apart from growth hiatuses, a variety of chemi­ etc. cal constituents found in corals may be used either to identify past bleaching/stress episodes or to describe • Organism/suborganism- physiology, conditions that existed during such events. At biochemistry, life histories, etc. present, an explicit bleaching "marker'' does not Data management through a centralized, exist; however, stressful conditions can be identified integrated program for validation, storage, and through time-series measurements of these chemical dissemination would comprise a major effort of the tracers. At uncomformities, such measurements may program. We see a need for development of stan­ yield insights as to the environmental stressors dardized methods and instrumentation, and for responsible for catastrophic events culminating in increased support for strengthening support of · mortality. The stable isotopes of oxygen and carbon taxonomic and paleoecological studies. can delineate temperature, solar radiation, and salinity changes over very brief time intervals (e.g. II. CORAL STRESS, BLEACIDNG, AND monthly to seasonal) in a coral's growth history. RETROSPECTIVE STUDIES Skeletally-bound trace elements such as cadmium A. Background and barium relate to ambient nutrient levels that existed at the time of precipitation and can also be Although we reached an apparent consensus correlated with temperature in reefs exposed to that coral bleaching events have become more oceanic upwelling. Other skeletal components such frequent during the past decade, much of our evi­ as trapped humic/fulvic material (and Ba) can be dence is anecdotal and our direct observations measured to trace the influence of runoff - a recog­ extend back only 30 to 40 years. nized cause of bleaching in localized settings. Still The extent to which current bleaching repre­ other trace constituents (e.g. Pb) may be used to sents an unusual, or possibly even unique, event over identify the influence of anthropogenic pollutants on longer time-scales is unknown. This is an important a coral reef. issue to resolve before a clear link can be established One suggested line of research with implications between bleaching and specific causative stresses for reconstruction of bleaching episodes involves related to global climate change. Retrospective characterization of the organic matrix left behind in studies using corals are a potentially rich source of coral skeletons. All previous retrospective studies information about the frequency and spatial distribu­ have focused on the inorganic portion of the skel­ tion of bleaching events. Skeletal growth records in eton. Since the bleaching response consists of an living, massive corals extend back as far as 200 to 500 ejection of photosynthetic algae, a residual chemical years in many areas where bleaching is now occur­ imprint might be expected as a consequence of a ring; longer time series are available using fossil rapid change in the metabolic fractionation of light corals. and heavy isotopes of carbon and nitrogen. Develop­ Major bleaching events that result in coral ment of such an indicator in the remnant organic mortality or lengthy intervals of zero growth leave content of corals would circumvent ambiguities behind a skeletal signature as a perturbation in associated with interpretation of the carbonate C-0 growth band morphology or as an actual hiatus or isotopic systems. unconformity. Stress bands or hiatuses can result Paleoecological studies using reef framework from a variety of influences such as grazing, preda­ samples have seldom been attempted. However, tion, thermal shock, salinity variation, disease, and from discussions at this conference it is apparent that storm damage, not all of which promote bleaching. there is no viable substitute for the long-term per­ The spatial distribution of synchronous stress spectives that this kind of research can provide to horizons should allow discrimination between studies of community succession and response to biological forcing factors and regional physical environmental perturbation. Accessibility to the parameters linked to climate. paleoecological record will vary depending on study Further characterization of a bleaching-type site. Examination of drowned reefs would, for origin for specific stress surfaces will probably example, require extensive drilling to achieve adequate spatial coverage. Uplifted terraces could be

22 closely inspected on a broader scale for evidence of of global warming, it can be difficult to distinguish historical stress events and successional evolution. elevated sea water temperatures from direct anthro­ It is important to note the link between pogenic inputs that may predispose or directly cause paleoclimate/paleoecological studies using corals coral bleaching. orals are also exposed to high fluxes and the need for comprehensive reef environmental of ultraviolet (U.V.) radiation compared to temperate monitorihg programs. Careful in-situ monitoring of or polar marine organisms. This consistent exposure environmental parameters such as T, S, water to U.V. radiation may be an important physical chemistry, and light provides the best means for parameter affecting the distributions and abundances accurate?' calibrating the climate record contained of reef-building corals. It is important to recognize within coral skeletons. and distinguish between different sources of stress if we are to understand the underlying mechanisms of B. ReseJch Priorities coral bleaching and to use them as indicators of environmental quality. 1. La~ratory and field experiments for calibra­ tion of specific coral-based traces. Verifica­ Whereas field data will continue to be an tiorl of signal fidelity using skeletal tracers to important source of information on the causes and reconstruct well-documented climatic and long-term ecological significance of coral bleaching, anthropogenic changes in the past century. laboratory investigations should be used to define more accurately the causes and cellular mechanisms 2. Acqbisition and analysis of longer coral­ of bleaching. Extant field observations can serve as based time series to discern secular variabil­ immediate sources of testable laboratory hypotheses. ity, long-term trends (including major Laboratory studies should examine the efficacy of climatic transitions/forcing), and cata­ various agents in inducing bleaching, the possibility strofhic events. that different agents lead to distinguishable 3. pursue paleoecological studies to provide "bleached phenotypes," and the physiological esti~ates of long-term reef system responses consequences of experimentally-induced changes in to previous perturbations: initially use zooxanthella populations. Although recent work has uplifted reef tracts; develop new sampling begun to describe the effects of U.V. radiation on syst~ms for submerged reefs. Note- reef organismal performance, its role in bleaching, alone ecol~gists must be active participants along or in concert with elevated sea water temperatures, withI geologists and paleoclimatologists.. remains incompletely understood. As part of the m. CO~L-ALGAL FUNCI10NAL BIOLOGY effort to elucidate and understand the effects of U.V. radiation, robust action spectra (biological weighting Rece-;tt observations of bleaching on coral reefs, functions) for processes of interest (e.g., photosynthe­ particularly in the Caribbean and eastern Pacific, sis) in corals should be developed. The coordination have focu~ our attention on the coral-algal symbio­ of laboratory studies with on-going ecological and sis as a potential indicator of the health of reef paleontological studies is a high priority. Collec­ ecosysterris. However, a better understanding of tively, the data may allow us to explain and predict symbiosis 1ibiology is required in order to evaluate patterns of bleaching. this issue. i I With respect to the population and community Bleac~ing has been described as the expulsion of level effects of bleaching, it is important to know zooxanthellae from the animal host or the diminution why corals manifest variability in their bleaching of photos>;nthetic pigment in the algal cells, or both. response. Field observations indicate that the onset As currentJy understood, bleaching should be of, and recovery from bleaching varies within and distinguished from photoacclimation, which involves between taxa. Some coral species exhibit different only changes in the concentration of photosynthetic sensitivity to bleaching at different geographic pigments as a response to variable light levels. In locations. It is not known whether the basis of this contrast toiphotoacclimation, bleaching is a manifes­ variability is physiological or genetic. Also, taxo­ tation of a change in the essential relationship nomic uncertainties make it difficult to conclude that between hbst and symbiont populations. Bleached individual coral species really do exhibit bleaching corals exhibit reduced fitness in terms of growth and variability. The zooxanthellae, which represent the reproduction. other biological half of the bleaching equation, are The association of bleaching with a variety of also a collection of species. No attention has been environmental extremes, most notably elevated sea paid to zooxanthella taxonomy in the context of coral water temperatures, strongly suggests that bleaching bleaching. Clearly, more taxonomic and population is a symptom of stress. Although it has been sug­ genetic work on both corals and zooxanthellae is gested that bleaching may be an early warning sign required before any predictions can be made about

23 the evolutionary consequences, short- and long-term, density and composition of grazing organisms, of of an increase in bleaching episodes. bioeroding organisms, and of planktonic propagules In conclusion, studies should focus on establish­ of benthic plants and animals. Major shifts in trophic ing: structure and function will accompany such biologi­ cal transitions. A. What factors contribute to the stability or instability of the coral-algal symbiosis. B. Research Priorities 1. Assemble field data and run simulations to B. Manifestations of destabilization of the investigate the sustainable levels of mortality symbiosis at the cellular, algal population, and in reef populations recently affected by individual coral levels. bleaching. C. Individual variation within and among species 2. Look for ecosystem level responses in of corals and zooxanthellae in their susceptibility addition to primary colonization by filamen­ to bleaching. tous algae, which arc common to all bleach­ ing episodes. IV. LONG-TERM ECOLOGICAL 3. Investigate how regional and local differ­ CONSEQUENCES ences in pre-bleaching community structure (including all other reef biota in addition to A. Background corals) affect the ecosystem response to and Bleaching kills or injures corals and other reef recovery from bleaching. biota and at some places, the extent, and recent 4. Link matrix or other population models to frequency of mortality has been so great that it has climate models on the one hand and cellu­ caused local extinctions of dominant species, cessa­ lar/physiological models, on the other, to tion of reef growth, and initiation of major reef improve the realism and predictive utility of erosion (Glynn, P.W. and W.H. deWeerdt, Science the population models. 252, in press). However, in the majority of cases the long-term consequences are not so obvious (Wil­ liams, D.H. Jr., and Bunkley-Williams, L., Atoll Res. Bull. No. 335:1-71, 1990); local extinctions and major erosion have not occurred even though bleaching episodes may have revisited the same coral stands on more than one occasion. This raises questions as to whether repeated bleaching-related coral death is ecologically sustainable. How often is too much and how much is too much? The questions may be addressed using transition matrix models that have been used to investigate the same questions in relation to Acanthaster planci damage on the Great Barrier Reef (Done, T.J., Coral Reefs 6:75-90,1987; Done, T.J., Marine Biology 100:51-611988). Starting conditions for the simulations are field estimates of coral population structure and injury at particular places. Model outputs are long-term population structures under regimes of simulated disturbance, colony growth, repair, background mortality and recruibnent. The approach may also be used to retrospectively assess whether current population structures could have developed under a regime of bleaching (or comparable disturbance) as that witnessed over the last decade. Bleaching followed by major coral mortality has downstream effects on ecosystem structure and function. Filamentous algae invariably colonize newly killed coral surfaces. However the biological succession which follows is known to be highly variable, depending upon the

24 1 interpretation of short-tenn ecological experiments, ORGANIZERS NOTE ON MONITORING regional or global occurrences of coral bleaching, and possible global climate change. Data must be gath­ Both working groups produced extensive ered at several scales to be appropriate for the documents on monitoring recommendations and assessment of each class of potential anthropogenic data needs. These were edited to eliminate redun- and climate change effect on reef ecosystems. dancy and1 produce a general statement of needs and objectiv

25 assess how anthropogenic or natural varia­ FINDINGS AND RECOMMENDATIONS tions in the past few decades may be reflected in available, but largely unanalyzed, historical The information and discussions presented in data. this document led the workshop organizing commit­ tee to a series of recommendations arising from the • Developing and employing ecophysiological workshop. One set of recommendations concerns "probes" and biological markers to detect implementation of an important collection of work­ stress in coral reef organisms, and thereby ing grouf. topics that should be pursued further. The sharpen our ability to understand and recog­ second ~t concerns conceptual and philosophical nize the responses of reef organisms to specific approaciies to the study of reefs and climate change. environmental perturbations. · 1. Jnformation about the future and past • Assessing the contribution of coral reefs to environMental status of coral reefs is required to the biological diversity of the marine environ­ transfer ctn intuitive sense that coral reefs are deterio­ ment, and indeed, the biosphere. rating intb a scientifically substantiated conclusion. 2. We recommend that scientists involved in Accordingly, we recommend that five international any program or initiative resulting from the Miami working groups be established as soon as possible workshop adopt certain conceptual and philosophi­ to plan aligorous assessment of the environmental cal approaches to the study of reefs and climate status of boral reefs and to address the impact of change, namely: ~d present future environmental conditions on • Scientists working in the context of this reefs. Each working group should be coordinated by program have a responsibility to interact with a steering committee and each consisting of 6-8 environmental resource managers as well as individuals. These groups might be formed the aegis app~opriate their scientific peers. The study of reefs, or any of an international institution (e.g., ICSU, other ecosystem, in an environmental context IGBP, SCOR, IOC) or a consortium of scientific represents a challenging intersection of societies Mth relevant interests. I scientific and management questions that Each working group should convene an initial requires such interaction. meeting tlefore or during the 1992 Coral Reef Sympo­ G~am. • A scientifically structured monitoring pro­ sium in The working groups should each gram is a critically important tool for use in a hold an irlformational meeting for the coral reef well designed research program examining scientific tommunity during the Guam meeting. Each change through time- one that involves the group shquld host larger workshops within one year constant scrutiny and refinement that can only after the Guam meeting. We note that one of the be provided by scientifically qualified partici­ strengths pf the Miami workshop was the active pants. Such environmental monitoring is a participation of oceanographers, climatologists, and logical and necessary component that is others frotn outside the boundaries of the traditional neither competitive nor inconsistent with "coral reef' research community; we view this research of the sort discussed here. approach ~s essential to constituting future working groups to bnhance the breadth and exposure of their • Coordination and comparison among re­ search sites and programs is required in any activities.! systematic study of reefs and global environ­ The topics to be covered by these groups, in ment, and should be part of the planning for more detah than could be done during the Miami such a program. Contrary to some opinions, workshop! would be: I comparability does not necessarily require •Coordinating comparative, long-term envi- common techniques or identical instruments ronm~tal monitoring research on coral reefs, to be used at all sites. In fact, today's changing to establish local, regional, and global trends technology probably makes excessively strict 1 of variability and sustainability of cotal reefs adherence to a single measuring device throu~h time. inadvisable. It is important, however, that • Using corals, coral reef sediments, and fossil data collection protocols and intercalibrations reefs as retrospective environmental recorders, be established so that data can be compared to establish the long-term history of environ­ between sites, or between times at the same mental variations recorded by coral reefs. site. • Using historical records about coral reefs and • Successful extrapolation from existing adjacent waters and land masses as recent observational assessments of reef status retrospective environmental recorders, to demands both objectivity and rigor. Since

27 much of our insight about coral reefs has been any individual ecosystem, including coral collected over a relatively short period of time reefs, is increasing roughly exponentially. -what might be termed the SCUBA age of Energy consumption, a measure of human underwater observation -some fraction of impact that includes both population and our present knowledge is undoubtedly economic growth, is also likely to increase colored by the short period of rigorous roughly exponentially in intensity over the underwater observations relative to the time next century. constants of natural variability and reef Addressing the proximate causes of anthropo­ development. genic environmental stress will be of little long-term • Establishing an inventory of reef resources in benefit if we do not also recognize and control the largely unstudied areas should be a significant ultimate sources of that stress. part of a study of reefs and global environ­ ment. Although coral reef research scientists have been able to learn ll)uch about coral reefs in particular geographic areas, vast areas of reefs, especially the abundant and species-rich reefs adjacent to developing nations in South­ east Asia, are largely unstudied; they are potentially stressed by large and rapidly growing human populations. • Training, especially of young scientists and technical support officers in developing countries, should be an integral part of the future plans for study of reefs and the global environment. Our ignorance about a large fraction of the world's reefs largely reflects the paucity of trained observers in many develop­ ing nations. Additional findings and observations include: 3. Coral bleaching is just one symptom of a large set of environmental problems confronting coral reefs world-wide. Observers are noting other signs of stress on coral reefs. In some instances, we can explain the stresses as being due to human activity. All too often, we do not have an explanation. The recommendations we have advanced above will help us to define and understand the effects of human activity on coral reefs and will perhaps help us control or alleviate the impacts of that activity. 4. Certain key environmental issues, that have substantial ramifications for coral reef and coastal ecosystems, require no further study for development of policy. Action on these issues need not be predicated on the outcomes of any study advocated by our workshop: • Widespread degradation of coral reefs and reef fisheries appears to be occurring world­ wide principally in areas were development in nearby coastal areas is accelerating. Land-use and human demography have important ramifications regarding the ecological''health" of coral reefs and other coastal ecosystems. • Human population, the ultimate source of anthropogenic stress on the biosphere or on

28 increase in world population and consequent envi­ APPENDIX A ronmental stress (deliberate coastal modification, marine resource exploitation, land use, waste dis­ Status of Knowledge on Coral Reefs and posal and pollution, etc.). Climate Change Issues Research needs: To prepare a consensus document on the status 1) It is extremely important to address the of knowledge concerning issues relating to coral reefs apparent discrepancy between GCMs that predict a and envi~onmental (including climate) change, the 2xC02 warming of up to 2 degrees in the tropics with organizirig committee prepared a draft version of the paleoclimate formulations that indicate low latitudes documerlt presented below and circulated it to the were not substantially wanner than present during participahts for comments or additions before the past Quaternary warm periods. The question of workshop. A revised version was distributed at the whether future warming will exceed the evolution­ workshop, and further amendments were solicited ary experience of reef organisms and communities and rece~ved. After incorporating these responses, will shape other, more specific research agendas. the document was reviewed for consistency with the I • 2) Assuming the possibility of atmospheric reports of the workmg groups. warming in the tropics, it is important to be able to The ~allowing material is presented as the best put credible limits on the possible amount of SST available\concise summary of community wisdom on increase, on either a sustained or transient basis, and the subject of coral reefs and environmental change. to identify (generically or specifically) areas that may The interition is to portray consensus viewpoints or not be subject to those limits. reliable i~formation, not controversial or untested 3) Improved predictions of changes in cloudi­ hypoth~. However, we recognize that this knowl­ ness, cloud patterns, precipitation, and winds are edge is not static, but will be expanded or supplanted extremely important assessing the effects of climate by futurejresearch. change on shallow-water marine environments. 1. ClimatrEnvironmental Change 4) Ocean models arc being rapidly developed The consensus on climate change used for and improved. It is important both to keep the reef workshoJ} discussion was based on the published research community in contact with the results of results oflthe Intergovernmental Panel on Oimate those studies and to encourage ocean modelers to Change (IPCC), and includes: address regions and issues of specific interest to questions of reef climate response. 1) a~ atmospheric composition change equiva­ II. Paleoclimate Studies lent to doubled C02 by some time during the middle of the 21st century; Retrospective studies based on reef sediments or 2) a +can global temperature increase of a few coral skeletons have direct relevance to establishing degrees (e.g., 1 5-4.5) for a doubling of preindustrial baselines for many of the phenomena discussed, and atmospheHc C02 levels; merit detailed consideration. Studies of Holocene 3) a l+titudinal temperature gradient, with high and late Pleistocene climate, climate change, and latitudes warming much more than low latitudes; coral reef environments and communities can 4) a rbultant sea level rise of 0.5-1.5 m (with address several important questions: present estimates favoring the lower values, at least 1) What aspects of climate can be reliably in the shott term); deduced from skeletal, sedimentary, or paleontologi­ 5) re~onal changes in cloud patterns, precipita­ cal evidence, and with what precision and resolu­ tion, and '*inds. tion? Althdugh dramatic improvement in the spatial 2) How have climates varied in the recent past, resolution \of and agreement between GCM models is what have been the rates and magnitudes of change, unlikely in the near future, significant progress can and how have reefs and related communities re­ be anticip~ted within the next few years. In this sponded to these changes? context, coral reefs and other marine and terrestrial 3) Can we identify past environments compa­ systems may have specific response characteristics rable to some or all aspects of the anticipated Green­ that will allow "fine tuning'' of GCMs. house GCC? If not, can we set limits on how differ­ As noh-climatic but important interactive ent (in terms of rates of change and absolute values factors, we recognize the probability of a significant of environmental parameters) present or future increase in surface ultraviolet flux due to strato­ climates will be from conditions experienced during spheric ozone depletion, and the probable steady the Quaternary? I

29 4) What kind of baseline can be established for 2. Parameter: Temperature trends and variability in late Holocene tropical Effects: Unusually elevated water temperature is climates, and what sort of GCC signal could be a stressor that can lead to bleaching of corals (and reliably detected in view of these trends and vari­ other zooxanthellate organisms), and may result in abilities? death if the "dose" (excess temperature times dura­ m. Reef Responses to Environmental Parameters tion of excursion) is great enough. It may have profound ecological effects on species composition A. The Physical Environment and ecosystem function, and its implications are 1. Parameter: Sea level great on temporal and spatial scales of evolutionary responses. Theoretical and empirical information Effects: Sea level rise (SLR) may be expected to: suggest the possible existence of an absolute tem­ a) Increase coral colonization, calcification, and perature upper limit, but conclusive data all point to growth on reef flats and coasts where coral develop­ the importance of relative temperature excursions ment is currently sea-level limited; (temperatures above the normal maximum to which b) Gradually deepen reefs where sediment the coral is adapted). Synergism with light exposure production and retention are not adequate to keep has been documented and interactions with other up with rising sea level; environmental parameters are likely. c) Increase and/or change the patterns of coastal Sources uf variation: Sea temperature excursions erosion, and affect the distribution of critical inter­ can result from normal climatic variation (e.g., El tidal communities such as mangals; Nino), local anthropogenic effects (e.g., artificially d) Increase water circulation and ventilation in restricted circulation, thermal effluents), or the currently restricted environments. regional effects of Global Climate Change. Current GCM results suggest tropical warming may be as e) Alter recruitment patterns and ecological • high as 2 degrees for doubled C02 Even a fraction of composition in benthic communities. this reflected in SST could greatly increase the f) Modify shallow water habitats. frequency of damaging temperature excursions. Sources of variation: Thermal expansion of ocean Extent, distribution, variability: Obvious vulner­ water; melting of continental ice sheets. able areas include shallow and/or restricted water Extent, distribution, variability: Global eustatic bodies with high insolation, and regions subject to rise is predicted (IPCC) to be 8-29 em by 2030 and 50- high natural fluctuation (e.g., El Nino sensitive). 150 em by 2100. Local relative sea levels will also With significant low-latitude SST warming, potential respond to tectonic effects, ocean current and atmo­ vulnerability would be ubiquitous. As with most spheric pressure shifts, and anthropogenic coastal such climate-driven shifts and variations, specific and near-shore modifications. Local factors may be predictability is poor. at least as important as eustasy in the short (few Issues, questions, research needs: decades) term. 1) Theoretical/model calculations of the maxi­ Issues, questions, research needs: Direct, short mum SST values to be anticipated, both on average term effects of SLR appear likely to be positive for and as transients (see discussion under I above). reefs if past/present patterns of recruitment and 2) The nature of physiological, genetic and calcification continue. However, the local conse­ evolutionary mechanisms of apparent temperature quences of reef failure to keep up with SLR may be adaptation (or selection), and the basis for differences serious both for reefs and for back-reef shorelines within and between taxa. and islands. Therefore, an integrated assessment of 3) Temperature sensitivities (and their mecha­ the net effect of GCC and other anthropogenic nisms) of other reef organisms, especially "keystone" changes on the growth potential of shallow reef communities is important. Indirect effects (via taxa. coastal impacts) are more likely to be negative than 4) Synergism with other acute and/or chronic positive in the short term, but local/regional in stressors. nature. 5) Temperature effects on ecological factors such Comments: In view of the climate scenarios as rates of reproduction, recruitment, mortality, adopted we do not consider the issue of sustained or growth, and dispersal of larvae that influence significant reductions in sea level important to processes such as succession, competition, predation, address. Estimates of present and recent past SLR and the food web structure. arc in the range of 1-5 mm/yr; near-term increases Comments: Temperature is a key variable: it has will be comparable to slightly larger. demonstrated and putative connections with recent

30 episodes of coral bleaching and mortality, and it has Sources of variation: Increases in tropical SST and both logical and intuitive connections with GCC. expansion of the geographic extent of surface water 3. Parameter: Oceanic currents temperatures capable of sustaining tropical storm activity are believed (but not proven) likely to Effects: Oceanic currents arc a primary control increase the frequency and/or intensity of tropical on nutrient levels, temperature, etc. by determining storms; changes in distribution are likely but less intensity and location of upwelling and water mass 1 predictable. Wave energy/direction changes will advection. These water movements have a second­ derive from presently unpredictable shifts in atmo­ ary conttbl on nutrient, sediment and contaminant spheric and oceanic circulation patterns (see discus­ distributfons by interacting with local sources sion above under currents). (typically anthropogenic). Currents control the distribution of reefs and competing communities by Extent, distribution, variability: Increases in storm transpo~ng their propagules, and therefore has frequency /intensity are most likely to affect regions ecologic~l, biogeographical and evolutionary impli­ currently subject to tropical storms, and their imme­ cations. ptey also have significant influence on diately adjacent geographic fringes. Wave energy sediment/coastal dynamics and local relative sea changes are not readily predictable other than to note that SLR may make local areas currently protected by level. l sea-level reefs somewhat more exposed to wave Sou es of variation: Oimate changes may be effects. responsiijle for transitions to new quasi-equilibrium patterns bf atmospheric and oceanic circulation. Issues, questions, research needs: 1 Exteht, distribution, variability: Are changes in 1) What arc the time constants of reef develop­ oceanic c rculation patterns predictable with any ment that relate to or are potentially controlled by the useful ce~ainty? Extrapolation of recent and inter­ recurrence intervals of storm events? mediate-term past trends offers some limited views, 2) Do reef communities (at various scales) but there 1is no understanding of their causes or an outside present areas of tropical storms differ signifi­ estimatio! of the probability of major state transi­ cantly (e.g., in structure, diversity, or sensitivity to tions, eib!er gradual or abrupt. storm effects) from their counterparts in storm-prone Issues, questions, research needs: Continued regions, and what may be the effects of extending develop.rtent of ocean and climate models will, if storm tracks or increasing frequencies? properly focused, address parts of the problem. Comments: Although catastrophic from human Continu~ or expanded marine paleoclimate studies viewpoints, storms are a natural phenomenon to aimed at ~etermining and explaining patterns and which reef systems are adapted. In the context of rates of past circulation or related changes can GCC and environmental change they are probably provide rrtajor insights. Studies of the resilience of most important as acute stressors whose direct existing cbral and related communities to changes in effects are followed by community recovery or currents (~.g., El Nino) may help with prediction of succession that may be controlled by effects of more possible effects. Studies of relationships between subtle chronic stressors. larval disJ,ersal and currents are needed. 5. Parameter: Ultraviolet light ComJrents: As with many major features of the Effects: UV light imposes physiological stress on glob~l clifate system, variability is at least as impor­ shallow-water and intertidal organisms and may also tant as change in the mean, and even less predictable. I be mutagenic. 4. Pa~ameter: Storms and wave energy Sources of variation: Progressive destruction of Effectk: Storms provide long-term episodic the stratospheric ozone layer by atmospheric pollut­ control of ~f community development by cata­ ants is expected to result in global increases in strophic ptuning and/or substrate renewal. They surface UV exposure, modulated by changes in cloud influence Jommunity succession and diversity cover. directly atjthe local level, and indirectly regionally. Extent, distribution, variability: Stratospheric Wave energy (including direction) operates more or ozone depletions are propagating toward lower less consistently as a component of winds and latitudes from initial polar effects, and are expected surface currents to shape the biological and physical to continue to do so. Variations in this depletion are development of reef communities. The upper end of large-scale, but these variations are not uniform with the "normal" wave energy spectrum grades into the longitude or in time. range of storm effects, with frequency of occurrence decreasing and becoming more variable as magni­ Issues, questions, research needs: tude increases.

31 1) Establishment of a good network, integrated stand coral and reef community responses, as in space and time, to make baseline measurements of functions of depth, to changes in mean light level and tropical marine UV levels for characterization and especially to changes in variance and/or distribution correlation of the apparently inevitable change. (e.g., seasonal/daily shifts in intensity/duration 2) Determination of the vulnerabilities (both factors). absolute and relative) to UV increase of shallow 2) Differential responses of hard coral and water tropical organisms. Information is needed not potentially competitive or destructive organisms only on acute stress to the mature organism, but on (algae, soft corals, bioeroders) to changes in light such life-cycle factors as fertility, larval survival, etc. regime are extremely important, implying increased as well. attention to non-coral species and communities. Comments: Of all of the potentially synergistic 3) a) Synergism of changing light levels with or confounding anthropogenic changes that will other (likely coincident) effects such as sedimentation interact with CCC or other environmental change, and nutrient loading is potentially important, as is b) this is one of the most important on a truly global synergism of existing light levels with high tempera­ scale. Monitoring is specifically mentioned for UV ture or salinity stress. since, unlike the case of temperature and possibly sea 4) Visible light changes in cloud cover due to level, prompt action may provide some reasonable CCC may lead to changes in light quality. What estimate of baseline exposures before ozone deple­ influences will spectral changes have on organisms tion increases in the tropics. including primary producers? 6. Parameter: Visible light Comments: As with several of the other param­ Effects: Light is required for photosynthesis. On eters, systematic differences between coastal and clear days, peak light values at the surface are in oceanic reefs are probable. excess of photosynthetic requirements in most 7. Parameter: Sedimentation locations. The water column attenuates light to the extent that photosynthesis and calcification both Effects: Extremely rapid sedimentation can diminish below depths of a few meters to a very few smother corals and other sedentary reef organisms. tens of meters. Increased radiant energy input at the Slower but significant rates are known to cause surface may or may not have effects on shallow reductions in coral growth rate. Occlusion of hard organisms, and may slightly extend the depth zone substrate with soft sediment can reduce coral recruit­ of active reef growth. Reduced light penetration, ment. Increased sedimentation is often, if not either by changes in water column characteristics or always, accompanied by elevated turbidity and by incident energy changes, can significantly reduce nutrient levels (discussed below). Among the the optimum depth zone for reef/reef organism mechanisms for deleterious effects are choking of growth. feeding mechanisms, sulfide generation, facilitation of bacterial "infections", and increased metabolic Sources of variation: Peak clear-day values of expenditure to maintain sediment free tissue. incident light are unlikely to increase due to atmo­ spheric change. However, average input could Sources of variation: Rising sea level will expose increase in areas where cloudiness decreases as a coastal and shallow-water sediments to changes in result of CCC. Decreased light availability could erosional and depositional patterns. Changes in result from increased cloudiness (considered prob­ currents, storm frequency or intensity, and precipita­ able by some climate specialists), atmospheric tion/runoff will probably change sedimentation rates pollution, or increased turbidity due to either and patterns on a local or regional basis. Non­ sediment input or in-situ effects of nutrient loading climate anthropogenic changes in land use (defores­ (see discussions below). tation, agriculture, construction) will also have major local and regional effects. Extent, distribution, variability: Although it is thought likely that a warmer world will be a cloudier Extent, distribution, variability: Increased vulner­ world, predictability of changes in cloud pattern is ability as a result of sea level rise will be ubiquitous, currently very weak. See sections on sedimentation, with local impacts predictable in part on the basis of nutrients, and turbidity for discussion of other the nature and exposure of local soils and sediments. contributing variables. Changes resulting from atmospheric or oceanic circulation pattern changes are probable but unpre­ Issues, questions, research needs: dictable without better models or actual data on 1) Although effects and interactions are qualita­ climate change. Non-climatic anthropogenic effects tively understood, we lack models or empirical may be predicted to some degree based on geo­ studies that would permit us to predict or under- graphic trends in population and development.

32 Effects will be significant only in proximity to land state (such a signal would have both real-time and masses; oceanic and atoll reefs may experience paleo applications)? redisbibution of existing sediments, but lack of 4) Will change in pC02 influence marine photo­ sources for a major increase in terrigenous material synthesis? input. Comments: In spite of the fact that this is one of IssUf!S, questions, research needs: Sedimentation the most reliably predictable effects of increasing (and related stresses, such as turbidity and nutrient atmospheric C0 of arguable significance to the loading)lare only occasionally and very locally acute, 2 p~obable whole carbon cycle, there are few experimental or but its general and sustained increase make theoretical treatments of the subject. It is experimen­ it i~port:ant to be able to monitor low-level changes tally straightforward, and could and should be and effec±ts, and to understand its synergism with addressed by coordinated field and laboratory other cru;onic and acute stressors. studies. The questions relate to all calcifying organ­ Cmrlments: See discussions of turbidity and isms, but are especially important for corals and nutrien~ below. calcifying algae. · B. 1fle Chemical Environment 2. Parameter: Salinity 1. P~rameter: Carbonate mineral saturation Sources of variation: Changes in salinity are state J primarily due to rainfall (and coastal runoff) varia­ Effects: The effects of changes in carbonate tion. Local/regional environmental modification saturatioh state are predicted but not empirically will be important in controlling runoff. Increased determi~ed: salinity is a possible side effect of increased evapora­ tion. 1) P~ssible reduction in calcification and/or extension rate of corals and other calcifying organ- Effects: Corals (and other reef organisms) are adapted to oceanic salinities and can tolerate only modest sustained increases or decreases in salinity. isms~) Ptsible shifts in skeletal chemistry/mineral­ Reef organisms will exhibit stress when subjected to transient variation far outside the normal range. ogy. 3) Ptsible shifts in sediment/community Extent, distribution, variability: High salinity dominante if thermodynamic preference for mineral excursions are likely to be locally very important but depositio affects organismic success. geographically restricted in extent. In some environ­

Sou es of variation: C02 dissolved in surface ments, increased evaporation or altered rainfall ocean w~ters will equilibrate with increased atmo­ patterns may be compensated for by rising sea level spheric ~02 and reduce supersaturation of b'opical (which can improve flushing of enclosed basins). surface Waters with respect to carbonate minerals. Effects due to changes in ocean circulation patterns Exteht, distribution, variability: Surface ocean will be minor but real. Low salinity extremes will be effects m~y be modified by changes in winds, controlled by climatic variations in rainfall (at upwelling, etc., but to a good first approximation, the present poorly predictable) and by coastal land-use effect canjbe estimated on a global basis. Smith practices that influence runoff. Reefs near land (unpublished calculations) estimates that tropical masses may be quite vulnerable to the combination saturati01\ states will go from 370% to 270% for of climate change and local/regional anthropogenic aragonite! 560% to 380% for low-Mg calcite, and effects, while oceanic reefs are likely to be little 290% to 2~5% for high-Mg calcite for a doubling of affected. ~tmosph,1 ric C02 and a 2-3 degree temperature Issues, questions, research needs: Information on mcrease. salinity stress responses and adaptation rates/ Issues, questions, research needs: mechanisms would be useful, for both corals and I other key reef organisms. 1) Within the predicted levels, is there an effect of saturation state on the calcification/growth rates Comments: Because of the local nature and the of major reef organisms? uncertain occurrence of the stress, this is not a relatively high priority. Local anthropogenic modifi­ 2) If the answer is yes, what are the implications cations to marine circulation and terrestrial runoff for community response to increasing pC0 in 2 are probably more important to impact evaluation. conjunction with rising sea level and increasing temperatures? 3. Parameter: Nutrients 3) Is there a chemical or mineralogical signature Sources of variation: Primary inputs of nutrients in skeletal carbonates that can be related to saturation are anthropogenic and local/regional in scale. CCC

33 may affect both local and global budgets by changing coral reefs. The incorporation of compounds within the frequency I amount of upwelling. skeletons and sediments may provide time markers Effects: Phosphate is believed to have a direct of pollution events and records of biogeochemical effect on coral skeletal development. Nitrate is also a processes under stress conditions. primary control on algal growth, and elevated nitrate Effects: Not well characterized, but some concentrations will directly favor more rapidly biocides are known to have deleterious effects on reef growing algae. Such conditions may facilitate organisms. changes of a reef community from one dominated by Extent, distribution, variability: The effects of corals to one dominated by bioeroders and non­ pollutants are local or regional depending on the scleractinian benthos. Chronic nutrient stress may extent of agricultural and industrial development. prevent coral community recovery from acute stress There is no particular GCC correlation. by favoring competitors of corals. Nutrient concen­ tration may also influence turbidity (see below). Issues, questions, research needs: Dose-response characteristics of reef organisms to long-lived and/ or Extent, distribution, variability: At present, acute widely used biocides or industrial contaminants are and major chronic effects are mosrlikely the result of not known. Screening is necessary to identify target local/regional waste disposal or contamination, compounds, and synergism with GCC or other local fertilizer runoff, or soil erosion. Ocean circulation is stresses needs to be assessed. significant to the distribution of anthropogenic inputs, but also an important influence on the natural Comments: Not a GCC issue, but probably one nutrient cycle. of the more neglected concerns in terms of anthropo­ genic effects on reef environments. Issues, questions, research needs: 5. Parameter: Turbidity t) Arc there direct nutrient stresses on reef organisms, or on the relationship of endosymbiotic Sources of variation: Planktonic and particulate algae to their hosts? If so, to what extent are they organic material from biological productivity is an interactive or synergistic with other stressors? important source of turbidity and is related to nutrient loading. The erosion and transportation of 2) Can we define nutrient levels that apparently sediment is also an important source (see above). place sclcractinian communities at a competitive disadvantage, or that represent a threshold for Effects: Turbidity is an important control of light synergism with other environmental stresses at the transmission to depth. community level? Extent, distribution, variability: The causes of 3) Arc bioerosion processes (grazing and boring) turbidity in reef waters are primarily local or regional directly or indirectly modified by nutrient changes and do not directly relate to GCC. However, turbid­ and how do these processes interact with other ity is likely to correlate with nutrient or salinity stresses? effects. 4) To what extent and at what rate are human Issues, questions, research needs: Identification of activities affecting regional or global (oceanic) the specific role of turbidity in cases of near-shore budgets of nutrients apart from the issues of GCC? environmental degradation. What are the probable consequences of these effects? Comments: Turbidity is only secondarily related Comments: Although not a major climate issue to GCC issues, but turbid waters may be an impor­ in the strict sense, nutrient loading and contamina­ tant confounding variable in near-shore coral re­ tion of marine waters is global in extent, and is sponses to environmental change. probably one of the most important anthropogenic IV. The Bleaching Question stresses on reefs. Its assessment in reef environments is complicated by the fact that biotic uptake of "Bleaching'' is the phenomenon of loss or nutrients is very efficient, leaving most of the evi­ expulsion of pigmented endosymbiotic algae by dence of excess nutrient levels in the biomass and corals or other normally symbiotic organisms. It is sediments rather than in the more readily measurable known to be a stress response, and can be induced by water column. high and low water temperatures, protracted dark­ ness and high fluxes of visible and/or UV light, 4. Parameter: Toxic/artificial compounds prolonged aerial exposure, low salinity shock, high Sources of variation: Runoff from land use sedimentation, and various pollutants. Some work activity is an important source of chemical com­ suggests that the production of active oxygen species pounds that pollute coastal waters. The proximity of within the tissues may be related to bleaching industrial/agricultural/waste disposal activities to induced by high temperatures and light levels, but it reefs is an obvious consideration in the 'health' of

34 is not clear if this represents a mechanism or if other more sensitized to look for and report the phenom­ stressors operate in the same fashion. At least in the enon? case of temperature (see discussion above) it appears C. What are the calibration factors (and associ­ that stress is not related to absolute temperature as ated uncertainties) by which bleaching observations much as to excursions above the normal ambient may be related to both local and regional SST and maximum. weather conditions? Are there criteria that can be Bleaching is a symptom. It may indicate suble­ reliably used to ascribe bleaching to temperature (or thal stres~, with the animals re-acquiring zooxanthel­ any other individual parameter) as a primary cause? lae and rtfovering. The animals may also survive for D. What are the consequences to other reef protrac · periods in a bleached or partially bleached organisms of massive bleaching events that result in condition extensive death of corals on a reef? Are biocrosion · In ca s of severe stress, bleaching typically processes enhanced? Are recovery processes dimin­ precedes ortality. Bleached corals are not normally ished? Does the Crown-of-Thorns phenomenon functiona , with reduced vitality, increased vulner­ provide a model of such events? ability to isease, and little or no calcification, reproducr,ve activity, etc. V. Resource Utilization Blea~hing episodes in reef environments have The preceding sections identified numerous been repqrted with increasing frequency and extents indirect effects of human resource utilization, prima­ over the ~st decade. The focus of attention has been rily in terrestrial environments that affect coral reefs. on tempetature as the causative agent; in some cases, Direct anthropogenic alteration of coral reefs and especiall~ those related to the 1982-83 El Nino, it is related communities may also occur as a result of well established that bleaching is correlated with and marine resource utilization. Specific examples almost cettainly caused by protracted periods of include: unusuali~Ehhigh water temperature. Other episodes A. Fisheries- perhaps the most dramatic and have bee anecdotally related to elevated tempera­ important potential effect is the reduction of the ture, but t least some bleaching occurrences do not herbivorous fish populations to the point where they appear to associated with unusual temperatures no longer control the growth of algae. Algal over­ and there is at least a suggestion that past high growth of reefs is often taken to indicate nutrient tempera re events have not always resulted in loading; in areas of heavy fishing pressure an alterna­ bleaching tive explanation is removal of control by grazing. It ha been suggested that coral reefs may be The effects can be the same, and can be strongly more sen itive indicators of early oceanic warming reinforcing where both fishing pressures and nutri­ (or other CC or anthropogenically-induced deterio­ ent inputs are high. Harvesting of reef organisms is ration of the marine environment) than direct not limited to fish; invertebrates are also harvested, instrumental measurements. In order to assess the both for food and for other markets (e.g., souvenir potential yalidity of that claim and the possible use trade in corals and shells). Fisheries result in direct of coral bleaching as an interpretable environmental alteration of community population structure that bioindicatOr, a number of questions remain to be may change the community response to environmen­ answeredj tal factors or changes. A. An understanding of the mechanism(s) by B. Mineral exploration and production- In which stnbsors induce bleaching and of the nature some reef areas, particularly adjacent to low islands, and extent of synergism between co-occurring reef limestone is the only economically available stressors i~ critical (specific aspects are discussed in construction material, and is quarried directly from other sections of this issues list). Subsets of these the reef. Oil exploration and production in reef areas I issues include the basis for differences in sensitivity can result in both direct physical damage and the bet~een a~d within taxa, the question of adaptation possibility of chronic or acute oil spills and incidental and/or se1ection in different temperature regimes, contamination. and the consistency of response for a given taxon C. Incidental damage- fishing with explo­ from a given locale (e.g., does sensitivity vary with sives or other destructive techniques can result in season, reproductive state, etc.). damage more extensive than the removal of the B. What is the baseline for assessing frequency target organisms. In areas of high tourism, including and extent of bleaching observations- to what some marine reserves, physical damage from boat extent did the 1980s have more bleaching and to anchors, divers, swimmers, waders, etc. may com­ what extent did they have more observers who were bine with incidental local pollution to place substan­ tial stress on the reef community.

35 Comments: Resource utilization stresses are VIL Communication and Implementation population-related, although mediated by a variety of cultural and economic factors. In the near term Although it was not a specified product of the workshop, it is useful to consider the institutional they are probably more readily identifiable and problems. The existence of this workshop (and many predictable than climate-induced or other environ­ mental stresses, with which they interact. Identifica­ others of similar orientation) testifies to a common belief that there are answers to questions or problems tion of baseline or "natural" conditions can be a that can be developed but that are not forthcoming severe problem, particularly where intensive local through the usual channels of scientific research and fisheries predate scientific observations. communication. Government agencies typically VI. Integrated issues -research and monitoring have time horizons to short and missions too restric­ tively defined to address integrated problems of this Several observations and conclusions seem sort (see W. S. Broecker, 1987, Nature 328:123-126). implicit or explicit in the above summary. These may Academic research tends to be too narrowly defined, merit discussion and refinement: and the publication of results in the refereed litera­ A. Many of the environmental stressors, both ture tends to be too slow to address effectively to GCC-related and of other anthropogenic origins, will address effectively rapidly developing and broadly primarily affect those reef systems in relatively close interdisciplinary problems such as global change. proximity to land masses. Although monitoring of When one adds in the well-known barriers to institu­ such reefs is both logistically simple and very useful, tional coordination and interdisciplinary communi­ a monitoring or research program that includes cation, it is obvious why we do not even know what oceanic or outer-shelf reefs removed from the we know, much less what we might know. complex mixture of near-shore effects will provide Workshops, commissioned reviews, targeted better controls for GCC-oriented studies. symposia, etc., are useful ways of assembling infor­ B. The known and/or probable synergism of mation and focusing attention within the existing stresses at both the organism and community levels system. Are there feasible methods of modifying our suggests: 1) an emphasis on mechanistic studies of approaches to facilitate the coordination and commu­ organismic stress responses, since single-parameter nication that should happen but doesn't? Could input-output studies of responses are of relatively some sort of structure of committees of review and little use in dealing with variable and/or non-linear correspondence be developed and supported with­ combinations of effects; and 2) more attention to the out having them tum into political playpens or robustness of response characteristics across taxa and institutional prizes? Can dissemination of informa­ environments, as generalization from local or spe­ tion be broadened and speeded without sacrificing cies-specific studies is usually difficult and often quality or proper credit? The climate community has unproductive. become reasonably well organized around the issue C. We need more attention to the issues of scale, of GCC- is there the potential for those working in uncertainty, experimental design, and the limits to tropical marine science to do likewise? knowledge (or limiting uncertainties), particularly in comparing or predicting responses across a wide range of time and space scales. D. Are there strategies by which instrumental and biological observations can be economically combined in a mixed monitoring network? What are the optimum approaches to designing and validating such a system, and on what time and space scales could it be expected to work? E. The issues of vulnerability and the impacts of environmental change are implicit in most of the foregoing material. However, second-order effects such as threats to marine biodiversity from large­ scale regional change have not been addressed; these could be better formulated on the basis of the pro­ posed improvements in knowledge about both the responses of organisms and communities and the locales or types of environments most subject to extreme stresses.

36 Frequency of data collection must be feasible yet APPENDIX B informative. Development of a Monitoring Program: Coordinated, centralized, integrated validation, Practical Recommendations storage, and dissemination of data is central to the program. Development of standardized methods 1. ORGANIZATIONAL and instrumentation, and increased support for Gh~en the urgency of the program, the follow­ strengthening taxonomic and paleoecological studies ing timejble was developed for implementation. will contribute to rational data management. We estimate $5 million per year during the first YEAR1 two years would cover purchase and installation of i A. Meeting of interested parties representing equipment, hire and training of technical personnel, mo~t/alllmarine laboratories conducting coral reef and establishment of the data processing center. research.i Election of a committee to handle initial Thereafter, operation costs will be about $3 million logisticaliphases of the program, and another to per year (1991 US$ basis), assuming 30 monitoring develop methods. Agreement as to participation in sites with two full-time technicians each, and a further ir~itiatives, and capabilities of existing labora­ central data repository. tories as~sed. 2. SCIENTIFIC B. ~ethods development meeting(s), producing a detailed manual. PRIORITIES FOR A MONITORING SYSTEM: C. LettersI of agreement from all laboratories. 1. Immediate establishment of a world-wide system for monitoring physical and biological YE~R2 parameters on coral reefs. Because many aspects of normal reef function are poorly understood, it may A. Data management development. be difficult to recognize, much less predict, effects of B. Hbnds-on methods workshops at the "inten­ environmental change. The sooner large-scale, sive" sitJ for all designated participants (i.e. the lead sophisticated, and well-managed monitoring begins, individuJI from each laboratory who will be respon­ the more of a baseline will be available, and the sible for program implementation at his/her site). greater the chances of early detection and under­ C. I~tallation/calibration of equipment. standing of change. Field and laboratory experimen­ D. E~tablishment of regional committees. tation (including microcosms) and complex com­ I puter simulations are valuable approaches to study YEAR 3 Program begins! of contemporary reef function. Field experiments relevant to global change must be coordinated with Am~ng the many issues to be decided are: I the monitoring network. A. Sites: Should the two levels of monitoring be 2. Laboratory and field experiments to deter­ based on present capabilities of participating labora­ mine responses of model system species to effects of tories? Basic monitoring would occur at all (about radiation and temperature. Radiation (via changes in 30) sites t9 gather extensive data. These would cover cloudiness, turbidity, and ozone) and temperature reefs representing diverse conditions and various (via the greenhouse effect) arc the most important disturbantc levels. At fewer sites (5-10), in addition long-term changes expected as a function of anthro­ to basic "fnitoring data, more intensive information pogenic modifications to the environment. would be gathered. These would presumably be at existing ~rine labs or MAB sites. 3. Development of microcosm facilities for bridging between laboratory and field. Nutrients, B. Measurements: among the most important short-term consequences Data ~ust be gathered at three spatial scales: of human activity and population growth, are I 1. Large scale- using satellites, LIDAR aircraft, particularly difficult to manipulate in the field at a GIS, oceanographic vessels, etc. scale required to study community level effects. 2. Community scale - physical parameters 4. Increased development and use of complex (temperature, salinity, tide, etc.), community struc­ model simulations for evaluating physical effects in ture (via biotic surveys, etc.), community physiology nearshore tropical environments and biological (P /R, etc.), phototransects, etc. interactions in high diversity reef communities. 3. Organism/suborganism level-biochemis­ 5. Publication of well illustrated manuals with try, physiology, life histories, etc. workable keys to permit reef scientists and techni­ cians to identify major taxa, particularly for regions C. Data management:

37 to be intensively studied. This should be backed by a. island (•U.S.V.I., •Puerto Rico) systematic research where necessary, for even the b. continental (•Panama, •Belize) best studied of reef organisms arc not well catego­ rized systematically. 2. Central-West Pacific 6. Accumulation of background information a. high island (•Guam, Moorea/Tahiti) on physical changes projected for the future, and b. atoll (?Enewetak/Marshalls?, Tuamotus) what happened in the past, as the context for study 3. Central/Northern Great Barrier Reef of effects of environmental change on reefs. Realistic a. inshore experiments that concentrate on likely changes within the next decade to century require informa­ b. offshore (Lizard Island) tion on magnitude and rate of projected changes; 4. South-east Asian fringing reefs change in variance may be more important in some 5. Indian Ocean (Seychelles) cases than change in mean. General predictions from modelers currently lack understanding of vital B. Reef sites in extreme or isolated environments particulars about temperature effects on nearshore 1. •florida Keys (including Dry Tortugas) tropical environments. This problem of modeling 2. •Hawaii must be coupled with testing through continued 3. -Gulf of Mexico (Flower Gardens) monitoring. Knowledge of past biota and conditions is critical to distinguishing potential changes that 4. •Eastern Pacific may have been experienced by reefs in the not-too­ a. upwelling distant past from those that have never been experi­ b. not upwelling enced. As above, means, variances, and rates of change must be considered. We predict that changes 5. Bermuda previously survived pose less of a threat. However, 6. Red Sea (Eilat, Sharm el Sheikh) since some changes are certainly novel, we cannot 7. Southern Great Barrier Reef (Heron Island) assume that a previously survived condition will be equally manageable when combined with novel 8. Japan (Okinawa) stresses. 9. Western Australia

WHERE TO MONITOR: Which reefs should be WHAT TO MONITOR: Understanding the studied is a compromise between the desire to have impact of environmental change on coral reefs is an broad geographic coverage ("extensive monitoring'') enormous task because of the number of potential and the need for detailed information ("intensive factors to be considered. Interactions are critical monitoring''). The following criteria are proposed. because the effects of multiple factors are often not I. General Objectives additive. Multiple sites and species are critical because communities may differ in their responses, A. Broad geographic coverage and even the same species at different sites may B. Major reef systems containing important respond differently, presumably because of evolu­ environmental gradients tionary selection and interactions with different C. Reefs in extreme habitats of particular species. interest in the context of local and global environ­ Our choice of physical variables to monitor mental change reflects the consensus that both the long-term effects D. Reefs having between/among them the of climate change and the short-term effects of potential for comparing closely related species or human activity and population growth must be populations investigated. Some factors are critical to develop­ ment of realistic, useful models. Parameters should E. Transects across tum-on/ tum-off regional be measured at least daily (and/or with daily gradients maximum/minimum values) at each location. The II. Specific Criteria anticipated pattern of expected change is noted for A. Previous history of study each. Experimentals should reflect as well as pos­ sible time scales of the expected changes (e.g., pulse B. Logistical support perturbation, press manipulations with gradual or III. Suggestions (• U.S. waters or U.S.-sponsored sudden onsets). Interactions more numerous and Ia bora tories) complex than those listed are expected, but con­ A. Major reef sites straints on replication and statistical analysis require 1. Caribbean

38 focus on a limited number of two- or three-way 7. Nutrient levels (including nitrogen, phospho­ interactions. rus, total inorganic carbon, and iron). Changing The species to be studied at the cell, organismal, mean and variance anticipated due to increased and community levels will vary depending on the human activities, although perhaps some upwelling question~ although some should be intensively changes. Proposed research: monitoring (water studied at all levels because of their importance as quality, remote sensing, community changes, depth model systems. A limited number of other species of profiles); microcosm experiments to examine compe­ conside~le importance in reef communities should tition between coral and algae; where possible be studi in less detail (e.g., sensitivity to tempera­ (enclosed lagoons and tidal flats), field manipula­ ture and .V.). The systematic status of all model tions. system sE"es must be clarified as soon as possible 8. Barometric and near-surface vapor pressure. to f~cilita e interpretation and comparison of results. Changed variability likely as storm tracks shift. · I. Ph sical factors Proposed research: monitoring. A. h~ isolation- 9. Wind and current speed and direction, wave climate, storms. No major trends expected over the 1. ~~I perature-of near-surface air, and of sea 1 next decade, although increased variance likely in at surface and to 100 m depth. Over the short term, context of mean temperature increase. Proposed increased variability likely to be more important than research: monitoring; monitor recovery of storm­ graqual can increase. Proposed research: monitor­ damaged reefs on fine spatial scales; computer ing (inclu ingcomparing sites with different tem­ ~rnes); simulation important because experimental simula­ perature transplants of organisms within tion usually impossible. regions I>Jtween sites of different temperature regimes (~.g., within Red Sea or within Eastern 10. Toxic pollutants and artificial substances. Pacific); l~boratory tests of temperature sensitivities Mean and perhaps variance likely to change. Al­ (to both variation and mean increase). ready present due to human activities and may continue to increase. Proposed research: monitoring ,2. sJ level (including vertical geodetic stability at several depths; laboratory sensitivity studies. and tides>f Predicted rise of little effect over the short term, except on reef flats where negative effects of B. Especially important interactions- extreme lqw tides may be mitigated. Proposed 1. Temperature +light + nutrients research: monitoring. I 2. Temperature +nutrients +biological interac- 3. Rainfall and/or runoff (fresh water), sedimen- tions tation, an4 turbidity. Changing mean and variance 3. Temperature+ light + pollutants expected. jWill be influenced by other climate changes (e.g. storms). Proposed research: monitoring 4. Storms + nutrients (study opportunistically) at several depths (in situ and remote sensing); II. Biological factors 1 laboratory and microcosm studies; field transplants. A. Model systems- 4. Salinity. Local changes only, due to factors 1. Indicator species (with special sensitivity to such as rurtoff and upwelling. Proposed research: temperature, nutrients, toxic pollutants, U.V., etc., or monitoring at several depths. changes therein) 5. CO!. Predicted gradual increase; tropics not 2. Species with broad geographic ranges (even if likely to differ from other sites. Proposed research: species complexes, these have enormous potential in laboratory ~nd microcosm experiments to determine comparative studies aimed at detecting evolutionary effects on iooxanthellae, other algae, and corals. responses to various environmental regimes) 6. SolJr radiation- incident U.V. and visible, 3. Ecologically key species absorbed shrface radiation. Increased U.V. via ozone 4. "Lab rats" for studies of physiology and cell depletion, flus changes in visible light due to biology changed cloud patterns and turbidity of water are predicted. Proposed research: urgent need for 5. Species of paleontological importance monitoring in tropics using scanning B. Other important species- spectroradiometcr (290-750 nm) at water depths to 1. Representatives of major morphological 5% visible light; laboratory experiments using both categories of corals (branching, massive, and weedy) acute and gradual exposures. Note that availability of instrumentation is currently a problem for the 2. Important competitors of corals (especially critical 290-300 nm region. algae and alcyonarians)

39 3. Important predators of corals and algal surement of chlorophyll as well as water clarity. grazers Coral photosynthesis and photosynthetic efficiency 4. Commercially important species. Overfishing can be estimated using other techniques. A study of and related activities have modified biological the fluorescence signals from chlorophyll and interactions and changed relative abundances of reef accessory pigments could be used as a diagnostic to organisms, and will continue to do so. Research measure algal invasion after a bleaching event. should consist of monitoring abundance and distri­ Although satellite remote sensing techniques are bution of reef organisms at all trophic levels; field useful to monitor changes in many large ecological manipulations of important predators, competitors, systems, resolution of these data is such that current grazers, symbionts, and bioeroders on reefs; micro­ remote sensing of coral reefs should be by high­ cosms and complex computer simulations of interac­ resolution airborne systems and associated ground tions. truthing, which are able to produce pixel sizes C. Water column characteristics- equivalent to the scale of coral colonies. Of particular use will be the definition of spectral signatures over 1. Phytoplankton (chlorophyll) concentration wavelengths ranging from UV through visible to at 2. Zooplankton concentration least the near-IR. Data already at hand indicate that D. Anatomy and physiology of the benthos­ in near-IR wavelengths, different species of corals may show small variations in spectral signatures. t. Uving coral cover Signatures change as corals undergo stress. Expan­ 2. Community structure (by some relatively sion of this type of work will allow researchers to simple measure-e.g., species diversity) gather data at scales needed to discern regional to 3. Community P /R ratios global scale changes in coral reef ecosystems. 4. Calcification/bioerosion ratios Complementing visible wavelength observa­ 5. Settlement/colonization rates tions are reflected IR and emitted IR. Reflected IR provides high definition of land-sea boundaries, and E. Individual coral colonies assists in quantification of areal mapping. Emitted t. Growth rate IR, particularly multispectral sensing, provides 2. Calcification rate temperature information at the scale of interest to the local patchiness that may be typical on coral reefs. 3. Photosynthetic parameters, including zooxan- Here again, aircraft observations will probably thellae/ chlorophyll density provide data at the scale required, with less atmo­ 4. P /R ratios spheric influence from the lower altitudes and 5. Reproductive activity therefore of higher accuracy. 6. Infestation with parasites, commensals, Other techniques may be useful in monitoring bioeroders coral reefs. HF coastal radar provides high resolu­ tion maps of sea surface current vectors at t -2 km THE VALUE OF REMOTE SENSING: Because resolution and at 3 hour time steps; typically tOOxtOO most coral reefs are distant from sophisticated square kilometers of coverage from two HF stations laboratories, they are ideal candidates for remote is possible. Synthetic Aperature Radar (SAR) or sensing- especially for techniques that employ Side-Looking Airborne Radar (SLAR) can also optical sensors about environmental effects of global provide information on currents and internal waves climate change. It is imperative that we begin now to that may affect circulation around coral reefs; both develop technology and research strategies for SLAR and SAR can be obtained from aircraft, but assessment of coral reef biomass and measurement of SAR at 25 m pixel resolution is available from growth using these optical sensors. . satellite. Scatterometer data from either aircraft or Optical remote sensing uses active (LIDAR) or satellite can provide detailed information on wind passive (wavelength scanners) instrumentation. Both stress vectors in and around coral reefs, which is systems have been used to study the characteristics valuable in data assimilation modeling of the cur­ of vegetation, but both have limitations as to areal rents and wave energy that may affect a particular coverage and/or detection specificity. LIDAR reef. should be able to measure the fluorescences charac­ THE ROLE OF EXPERIMENTATION: The teristic of most corals. Sun-induced fluorescence of effects of environmental change on reefs must be zooxanthellae also could be measured. Reflectance studied at several levels. Central is the individual. (spectra)) through radiometry or from a pulsed laser In some cctses we may need infonnation on physiol­ at the appropriate wavelengths would allow mea- ogy and cell biology of the response, particularly to

40 clarify future research directions. Interactions between individuals eventually translate into a APPENDIX C community response. Different methods are appro­ priate to each hierarch~callevel. All can be studied as Written Materials Submitted to the Workshop• paJ1 of, or in conjunction with, monitoring. Achituv, Y. and Dubinsky, Z., "Carbon Budgets in I. Cell biology Marine, Mutualistic Associations between labobtory experiments1 Microalgae and Cnidarians," Comparative Physiol­ I ogy, 1990, vol. 5, pp. 36-48. ll. Physiology 1 Ben-Zion, M., Achituv, Y., Stambler, N. and labobtory experiments Dubinsky, Z., "A Photographic, Computerized m. lrdividual growth, reproduction, mortality Method for Measurements of Surface Area in , laboiatory1 or microcosm2 experiments (depend­ Millepora," Symbiosis, 10(1991)115-121. ing on sc te) Buddemeier, R.W. and Hopley, D., "Tum-ons and 1 field monitoringl Turn-offs: Causes and Mechanisms of the I Initiation and Termination of Coral Reef IV.

41 Glynn, P.W. and de Weerdt, W.H., "Elimination of •unless noted with the citation, authors' ad­ Two Reef-Building Hydrocorals from the Eastern dresses and can be found on the Jist of participants, Pacific Fo11owing the 1982-83 El Nino Warming in the Introduction. Please contact the authors for Event," Sdence, Vol. 252, 1991 (in press). copies of submissions. Glynn, P.W. and D'Croz, L., "Experimental evidence Due to the copyright Jaws, certain artides could for high temperature stress as the cause of E1 not be copied and sent to those who requested them. Nino-coincident coral mortality," Coral Reefs Please contact the authors directly. {1990) 8:181-191. Dunbar, R., WeUington, G., "Oimate Change, Goreau, T.J., Hayes, R.L., Clark, J.W., Basta, D.J. and Bleaching and Long-term Coral Growth Records, Robertson, CN., ''Elevated Satellite Sea Surface " June 1991 (2 page handout). Temperatures Correlate with Caribbean Coral Reef Bleaching," NOAA Technical Report N.O.S. Dunbar, R.B., We11ington, G.M., Colgan, M.W. and #137:1-60 (1991) (in press). Glynn P.W., "Eastern Tropical Pacific Corals Monitor Low Latitude Oimate of the Past 400 Goreau- Global Coral Reef Alliance, 324 N. Bedford Years," Proceedings of the Seventh Annual Pacific Road, Chappaqua, NY 10514 or Hayes- Depart­ Climate (PACUM) Workshop, April1990, J.L. ment of Anatomy, Howard University, Washing­ Betancourt and V.L. Tharp, eds.,1991, California ton, D.C. 20059 Department of Water Resources. Interagency Halley, R.B. and Hudson, J.H., "Sea Temperature and Ecological Studies Program Technical Report 26. Coral Bleaching in the Florida Keys: No Relation Elms, J.D., "Sea Surface Temperature Trends in the to Global Warming... Yet," 1991 (1 page sum­ Caribbean Sea and Gulf of Mexico, 195Q-1989, " mary). June 17, 1991 (9 pages). Hallock-Mu11er, P., ''Why are nutrients Killing Enfield, D. B. and Cid S., Luis, "Low-Frequency Florida's Coral Reefs so Difficult to Measure?", Changes in El Nino/Southern Oscillation," June 1991 (10 page handout). February 1991,17 pages (resubmitted to Journlll of Hardy, J. and Gucinski, H., "Stratospheric Ozone Climate for publication) Depletion: Implications for Marine Ecosystems," Enfield, D.B., "El Nino, Past and Present," Reviews of Oceanography, November 1989, pp. 18-21. Geophysics, 27, 1/February 1989, pp. 159-187. Hardy- Huxley College of Environmental Studies, Glynn, P. W., "Coral Reef Bleaching in the 1980s and Western Washington University, Bellingham, Possible Connections with Global Warming," WA9822S. Trends Ecol.&Evol. Vol.6, no. 6, June 1991. Hudson, J.H., Halley, R.B., Joseph, A.J., Udz, B.H., Glynn, P.W. and Colgan, M.W., "Defense of Corals and Schroeder, D., "Long-Term Thermograph and Enhancement of Coral Diversity by Territo­ Records from the Upper Florida Keys, Compari­ rial Damselfishes," 7 pages. son Between Sites," 1991, 116 pages. Glynn, P.W., "Predation on Coral Reefs: Some Key IPCC Scientific Assessment-Climate Change, Execu­ Processes, Concepts and Research Directions," tive Summary, 2 pages. Sixth International Coral Reef Symposium, Johnson, H.P., Wilson, J.C. and Strickland, R., "New August 1988. Hard-Rock Drill Successful in Deep Sea Test," Glynn, P.W., Cortes, J., Guzman, H.M. and Rich­ Sea Technology, December 1990, pp. 43-46. mond, R.H., "El Nino {1982-1983) Associated Johnson- School of Oceanography, University of · Coral Mortality and Relationship to Sea Surface Washington, Seattle, WA 98195. Temperature Deviations in the Tropical Eastern Johnson, H.P., "Next Generation of Seafloor Sam­ Pacific, " 7 pages. plers," EOS, vol. 72, no. 7, February 12, 1991. Glynn, P.W., "El Ni-o-Southern Oscillation 1982- Kinsey, D.W., and other authors, series of articles 1983: Nearshore Population, Community, and from Search, Vol. 22, No.4, June 1991. Ecosystem Responses," Ann. Rev. Ecol. Syst. 1988, 19:309-45. Kinsey, D.W. and Hopley, D., "The significance of coral reefs as global carbon sinks-response to Glynn, P.W., "Coral Mortality and Disturbances to Greenhouse," Palaeogeography, Palaeoclimatology, Coral Reefs in the Tropical Eastern Pacific, Palaeoecology (Global and Planetary Change Global Ecological Consequences of the 1982-83 El Section), 89 (1991) 363-377., Elsevier Science Nino-Southern Oscillation" P.W. Glynn, ed., Publishers, Amsterdam. Elsevier Oceanography Series. {1989).

42 Klein, R., Loya, Y., Gvirtzman, G., Isdale, P.J. and Savina, L.A. and Sebens, K.,"Short and Long Term Susie, M., "Seasonal Rainfall in the Sinai Desert Recovery from Bleaching - A Comparison of during the late Quaternary inferred from fluores­ Naturally Occurring and Laboratory Induced cent bands in fossil corals," Nature (Int'l), Vol. Bleaching," June 1991 (1 page handout). 345, No. 6271, pp. 145-147, May 10, 1990. Sebens- Northeastern University Marine Science Knowltorl, N., Weil, E., Weigt, L.A. and Guzman, Center, Nahant, MA 01908 H.M.) "Sib1ing Species in Montastraea Annularis, Shen, G.T., "Utility of trace element geochemistry in Coral! Bleaching, and the Coral Oimate Record," reconstructing environmental change in coral {in reyiew for Science) June 1991 (3 page handout reefs," June 16, 1991, Draft Statement, 5 pages. ba on 24 page manuscript submitted). Les~r Shick, J.M. and Lesser, M.P., "An Overview of M P., Stochaj, W.R., Tapley, D.W. and Shick, Photooxidative Stress and Defenses against It in J.M., Bleaching in coral reef anthozans: effects of Coral Reef Symbioses," June 1991 (15 page irradi nee, ultraviolet radiation, and temperature handout). on th activities of protective enzymes against activ oxygen," Coral Reefs (1990) 8:225-232. Shick, J.M., Lesser, M.P. and Stochaj, W.R.''Ultraviolet Radiation and Photooxidative Loya, Y., Changes in Red Sea Coral Community 1 Stress in Zooxanthellate Anthozoa: the Sea Struc~re: A Long-Term Case History Study," Anemone Phyllodisius semoni and the Octocoval The ~rth in Transition, Patterns and Processes of Clavalaria sp., " Symbiosis 10 1991 pp. 145-173. Biotidmpoverishment, G.M. Wooclwell, ed., 1986, Smith, S.V., "Oimate Change, Carbonate Mineral pp. 3~9-384. Saturation State, and Coral Reef Calcification," Maul, G., r'lmplications of Oimate Changes in the June 5,1991,7 page handout. Wide~ Caribbean Region," available from: Caribbean Environment Programme UNEP, 14- Topinka, J.A., Bellows, W. Korjeff, Yentsch, C.S., 20 Poft Royal Street, Kingston, Jamaica, CEP Characterization of marine macroalgae by fluore~ence signatures, Int. J. Remote Sensing, Tech1'cal Report No.3, 1989. 1 1990, Vol. 11, No. 12,2329-2335. Mau ~, G., 'Temperature and Sea Level Change," June 1991, 8 pages. Ware, J.R., Smith, S.V. and Reaka-Kudla, M.L., "Coral Reefs: Sources or Sinks of Atmospheric Cq?" Mearns, L.O., "Analysis of Increases in Sea Surface manuscript submitted to Coral Reefs, 22 pages Tem~rature Extremes with Global Warming," June~~, 1991, 15 pages (Draft). Ware, J. and Reaka-Kudla, M., ''The Suitability of Coral Bleaching as a Detection Mechanism of Ogden, J.q:., Information Sheets on SEAKEYS (Sus­ Global Temperature Change," June 1991 (9 page tained Ecological Research Related to Manage­ handout). ment bf the Florida Keys Seascape) and CARICOMP (Caribbean Coastal Marine Produc­ Ware- Atlantic Research Corporation, 1375 Piccard tivity)~ Drive, Rockville, MD 20850. Ogden - Ftorida Institute of Oceanography, 830 First Wellington, G.M. and Gleason, D.F., "Potential 1 Effects of Increased Levels of Ultraviolet Light on Stree~uth, St. Petersburg, FL 33701. Reef-Building Corals," June 1991 (4 page hand­ Quinn, W ., "Southern Oscillation-Related Climatic out). Chan es, "June 1991, 3 page handout. Williams, E.H. and Bunkley-Williams, L., "The M~., Reaka, "The Ecology and Evoiution of High World-wide Coral Reef Bleaching Cycle and Biodi ersity on Coral Reefs" and "Bioerosion ~nd Related Sources of Coral Moratality," Atoll It Significance on Coral Reefs," June 1991 (1 Research Bulletin No. 335, National Museum of page ~andouts). Natural History, Smithsonian Institution, Janu­ Reaka - Department of Zoology, University of ary 1990. Maryland, College Park, MD 20742. Williams, E.H., Caribbean Coordinator, Department Rowan, R.l"Taxonomic Issues in Algal-Animal of Marine Sciences, University of Puerto Rico Symbioses," June 1991 (3 page handout). - Marine Ecological Disturbance Information Center, Santavy, b.L., "Issue Paper: Microbiological Consid­ Summary 8, June 15,1991 erations- Microbial Ecology of the Bacterial Flora Naturally associated with Coral and the Micro­ - Marine Ecological Disturbance Information Center, biological Processes involved in Coral Bleach­ Summary 7, February 10, 1991 ing," June 1991. -Publications of the Caribbean Aquatic Animal Health Project (list)

43 Ad Hoc Plenary Talks, June 19,1991 APPENDIX D Connell, J., "Detection of significant trends in popu­ lations on reefs and attribution to global climate Abstracts of Invited Plenary Talks change" Coral Reefs, Climate, and Environmental Dubinsky, Z., "A biological rationale for monitoring Change strategies" Hallock-Muller, P., "CZCS scenes of fluvial chloro­ Robert W. Buddemeier phy11 plumes and their ranges through the Kansas Geological Survey Caribbean and Atlantic" In order to discuss relationships between Hopley, D., "Paleo-oceanographic records in Porites environmental-or climate-change and organism cores'' or ecosystem responses, we need to define some Jackson, J., "Pleistocene Caribbean coral reefs" terms and address issues of scale. Environmental change is what is experienced at the local level; its Knowlton, N., "Sibling species in the 1ab rats' of causes may be local and unique, local and part of a coral research - implications for environmental larger pattern of trends ("Global Change"- for bioassays, ecological moinitoring and recon­ example, large-scale increases in waste dumping or structing the past'' UV exposure), or the result of large scale systematic Loya, Y., "Climate change and coral reef communi­ changes (Global Climate Change, or GCC). It is ties of the Sinai" important to note that local changes resulting from Maul, G., "Observations of temperature and sea level GCC are not necessarily consistent or monotonic; some areas may become cooler even in a world that change during the last 100 years" is warmer on the average. Mearns, L., "Predicted changes in sea surface tem­ Many definitions of climate are possible, but for perature extremes in the tropics under global the purposes of quantitative prediction, climate is warming" defined in terms of quantitative measurements of Quinn, W., "Southern Oscillation-related climatic primary physical and chemical variables over multi­ changes" decade and global or large-region averages, with Santavy, D., "Importance of the microbial communi­ assodated statistics. To be relevant to climate issues, ties as a response measure to ecosystem stress'' biological responses must be explainable or cali­ brated in these same terms. This is complicated by Smith, S., "1be role of coral reefs in global carbon scale mismatches-organisms and communities fluxes" function at a very local level, while the concept of Wicklund, R., "Temperature Spike and observed "climate" has an intrinsically larger scale, with severe coral bleaching, summer 1990" limitations on deterministic links to short-term or small-scale observations. Yentsch, C., "Potential and present practices for remote sensing of coral reefs" In addition to problems of scale, efforts to use bioindicators must contend with natural variability and fundamental uncertainty about models and predictions. It has been suggested that coral bleach­ ing increased substantially in the Caribbean in the 1980s, that this was the result of elevated tempera­ tures, and that this in tum might indicate the advent of the greenhouse effect. Both the definition of climate and a review of instrumental temperature records indicate that a decade of regional observa­ tions falls far short of the time and space scales necessary to define or detect a climate trend. Fur­ thermore, offshore water temperature data indicate that any modest warming trend in the shallow water during the 1980s was superimposed on a 40-year cooling trend for the region as a whole. Although climate models predict a modest tropical warming as a result of the greenhouse effect, paleoclimate data from past (6 ka, 125 ka) warm periods hint at cooler

44 tropics. With judicious choice of conceptual model, In order to assess relative importance or sensi­ any temperature trend can be interpreted as evidence tivity, these same stressors may be categorized by ofGCC. their primary pathway or mechanism of delivery to As a factor in global carbon budgets we must the local reef environment. This list is given in Table recognize.that coral reefs are insignificant on time 2; although not extremely rigorous, it provides a scales rel~ant to GCC; their C0 fluxes arc trivial basis for identifying signal amplification possibilities. 1 2 compa3to anthropogenic releases. However, their responses to climate change are interesting for Table 2: Dominant Pathways of Stress Delivery several re, sons. Although reefs would appear particularly vulnerable to climate change because of Hydrographic their restriction to warm, shallow marine environ­ Atmospheric Hydrologic ments, prJsent community structures and inventories of organistns appear to have undergone little change Freshwater through the repeated climate and sea level cycles of Temperature Sea level Nutrients the Quatetnary period. Detailed knowledge on uv light Currents Sedimentation shorter tidte scales is limited to the very few decades Visible light Storms/waves Taxies of intensiJe observations in the post-SCUBA era, but COzchange Turbidity chemical ~nd physical records of reef environments ~n contained annual skeletal growth bands have the From the standpoints of sensitivity, vulnerabil­ potential to extend retrospective studies to time ity, and monitoring, marginal environments are scales of Jnturies. Environmental response charac­ particularly sensitive to change because of their steep teristics ort all scales are relevant to the potential use gradients and physical constraints. Coastal zones are of reef codtmunities or individual taxa as real-time a particularly good example of such environments, 1 indicators of environmental stress. Equally impor­ and a large fraction of the world's coral reefs occur tant is the bpportunity to use environmental change within coastal zones or their physical extensions, as a large-kale experimental probe to test hypotheses enclosed and/or shallow basins or shelf environ­ about o~nism and ecosystem responses and their . I ments. In such locales the hydrologic pathway has a mech amsms. particularly high signal amplification because Envirbnmental factors that favor or stress reef changes are integrated over very large land areas and ecosystem~ are well known; Table 1 lists the stres­ focused (e.g., through runofO onto the narrow coastal sors, subdtvided according to whether increases in zone. It is important to note that the stressors stress ove~ the next few decades arc more likely to delivered via the hydrologic pathway are generally result fro.J changing climate or from other anthropo­ those in the "other" (non-CCC) source category. geniC envirnmenlal alterations. This analysis leads to the conclusion that reefs in proximity to land masses or in relatively shallow or Table 1: ~ominant Sources of Near-Term Coral enclosed basins will be particularly sensitive (or Reef Stresses vulnerable) to the effects of environmental change, I but will have a low specificity for climatic variables. qimat~ Other In the near term, the suggestion is strong that local and regional effects of population growth, land use, etc., will have more effect on reefs than the more rise'' Ultraviolet lighflt .. distributed and gradual climatic changes. Oceanic Seale+! reefs are probably more sensitive to the truly climatic Nutrients( .. ?) cqchangcs" component of environmental change and could serve Tempe~ature change.. Sedimentation as control sites for studies in the more complex Visible lught Turbidity nearshore environment. Specific stress responses could be investigated on a local basis, but problems Current/' storm change Taxies I of scale and variability would require extensive (Fresh water) Resource use networks of long-term observations if signal detec­ (Fresh water) tion or "average" response determination were desired. " global, trends monotonic .. global mean trends monotonic, significant spatial/ temporal exceptions

45 Coral Bleaching: A Cell Biological Perspective shock. Similarly, at elevated temperatures (32°C. ), a seven hour exposure is sufficient to evoke release of Leonard Muscatine zooxanthellae. Department of Biology University of California The mode of release is unique. The sea anemone A. pulchella and the coral Pocillopora damicornis release Los Angeles, CA 90024 whole endoderm cells with their zooxanthellae. The From a cell biological perspective, coral bleach­ phenomenon is interpreted as the result of cell ing (i.e. loss of zooxanthellae) may be viewed gener­ adhesion dysfunction brought on by the temperature ally as a problem in the regulatory biology of algae­ extremes. invertebrate symbiosis. How might temperature extremes evoke cell The population density of zooxanthellae in reef­ adhesion dysfunction? We hypothesize that tempera­ building corals is often constant and predictable ture perturbations cause membrane thermotropic within a species. It may be regulated before or after effects in host cells. This leads to failure of ion pumps the the zooxanthellae undergo mitosis. Premitotic and then passive flux of ions. Calcium influx is regulation may be achieved by nutrient limitation or known to cause collapse of elements of the selective release of zooxanthellae metabolites. cytoskeleton, and concomitant dysfunction of cell Postmitotic regulation may be result from digestion adhesion molecules. In preliminary tests of this or release of excess zooxanthellae. Population density hypothesis, we have observed release of host cells at may also be deregulated. For example, sustained normal maintenance temperatures with pharmaco­ exposure to inorganic nutrients causes a dramatic logical agents that elevate intracellular calcium ion increase in zooxanthellae population density ("~p concentration. regulation"). In contrast, temperature extremes, low salinity, and ultraviolet radiation cause release of zooxanthellae ("down regulation"). Coral bleaching may then be viewed as a problem in down regulation of population density of zooxanthellae. The cell biologist asks ''What are the signal transduction phenomena associated with down regulation of population density of zooxanthellae?" To answer this question, a case study of bleaching in the tropical sea anemone Aiptasia pulchella and selected reef corals is described. In this study we examine bleaching in response to low and high temperature. When the tropical sea anemones Aiptasia pulchella and A. pallida are exposed briefly to subnor­ mal temperatures (i.e. cold-shocked), and then rewarmed to ambient temperatures, they release substantial numbers of zooxanthellae. Release varies with cold shock temperature and duration. A four­ hour cold shock at 4° evokes release of 40-55% of the zooxanthellae after 12 hours, and in some cases up to 97% in 72 hours. As shock temperature in­ creases to about 16°C., fewer zooxanthellae are released. Above about 16°C, and up to 28°C, the response is similar to that of unshocked controls. Release is greater at 4° and 10° if the duration of exposure is extended up to about 7- 8 hours. Longer cold shock duration elicits no additional release. Rewarming to at least 17. soc. is essential for evok­ ing maximum release. Eleven species of scleractinian corals from the Seychelles Islands, St. Croix, and Hawaii also released zooxanthellae after a four-hour cold shock between 12° and 18°C. Release at 12° ranged from about 20 to 75% after 12 hours, depend­ ing on species, geographic location, duri:ition of cold

46 Systems Level Management, Monitoring, and The Great Barrier Reef Marine Park: Research: The Australian Perspective on The GRBRMPark is not a national park in the Environmental Change conventional sense. Rather it is a large piece of submerged territory which is managed by the '1 Donald W Kinsey G eat Barrier Reef Marine Park Authority Federal Government, assisted by the State of Townsville, Australia Queensland, for balanced, sustainable multiple use. It is 350,000 km2 in extent; includes essentially all of lear that coral bleaching and Greenhouse the eastern continental shelf north of 23°N; contains are now i extricably entwined, at least in the popular nearly 3000 separate reefs, 120 vegetated islands of media. ch of my talk will relate to this relation- reefal origin, and 600 high islands; has the largest ship, exa ine the present status of its credibility, and tidal regine of any reef system (spring tidal range more im rtantly will consider the overall status of from 3 m to 6 m); has typically strong currents and reefhealt . wind fields, and the associated frequently rough conditions; has never been the site for significant On this occasion I will be concentrating on presentin~ subsistence use by man; and is adjacent to a large the perspective of the agency responsible continent and subjected to all its natural and anthro­ for the management of the world's largest, multi-use, pogenic inputs. The GBRMP has a high profile on the protected Imarine area, not the perspective of a coral world scene but in actual fact contains only about 3% reef scientist which is the role in which many of you of the actual reef area of the world (compare with the have knor me for so long. Caribbean which has about 9%). Greenhouse: The commercial value (without multipliers) of the GBR Region is approximately $1000 million, with •1 Gree house is characterised by a greater level $300-400 million from offshore and island tourism of un ertainty and higher levels of opposed and recreation, $100-200 million from commercial Vic ints than most global environmental fishing, and the majority of the remainder from issue . The more we find out the greater the onshore tourism. unceI amties, • seem to beeorne. Management of the GBRMP is primarily by ~uddemeier • ·Bob (Reef Encounters, 1990) has zoning for preferred patterns of use. This overall suggerted that we currently seem to have the strategy is combined with special management plans greatest separation between the political and publi~ for areas requiring specific attention, and a permit push for something to be done, and system for all commercial users. The principal tcchnieal scepticism about the details and .. I vehicle for implementation and achieving compli­ rca I tties. ance is education, and the GBRMPAuthority spends • Many postulated scenarios for Greenhouse much of its effort and budget in working with user have become enshrined as hard predictions groups and the general public to achieve this. whichl some of us in government planning However, enforcement is used as a last resort when have~d to live with, simply because there is clearly necessary. ~othi g more definitive to displace them. Environmental Problems in the GBR: • It wa concluded by the Inter-Governmental Panel n Climate Change (1990 Overview) The environmental problems with which the that: "pnequivocal detection of enhanced Authority has to cope, in order of probable long term Green~ouse is not likely for a decade or significance: more." • PERCEPTIONS. Public opinion and the • The Jnfused situation is typified by the Male opinions of specific interest groups almost Declat1ttion (1989) made by policy setters from certainly pose the greatest "environmental" small states in which it was concluded that problem for the GBRMPA. This situation is "small states should take adequate measures greatly aggravated by the fact that such to pro~t1 vulnerable natural ecosystems such perceptions are so often very poorly sup­ as coral reefs and mangroves" - I suggest ported in fact. The vicarious users (media that there are few measures indeed that can be exposure only) constitute perhaps the biggest taken on the basis of our present knowledge "lobby" group, and the least balanced in and we certainly do not know the time frame overall understanding. within'which to take them. • Nutrient build-up- agricultural practice and urban development/ sewage

47 • Effects of all forms of fishing We know that reefs in many parts of the world • Crown of thorns starfish tolerate very elevated temperatures for considerable periods of the year without bleaching. eg"Arabian • Effects of tourism Gulf, 36-39"; One Tree Is. GBR, 33°+ every mid­ It should be noted particularly that I have not summer daytime low tide on the reef flat (in the included either coral bleaching or Greenhouse. same place that also tolerates 16-19" on winter night low tides). We probably assume that this is because Reef Health: of adaptation of the species present to these unusual Arc the GBR reefs sick today? Are the world's conditions over very extended time. How abrupt, reefs sick today? -are they "running a tempera­ and more importantly how patchy or localised will ture"? Are reefs well enough to respond to a rising Greenhouse temperatures be? Jokiel and Coles Greenhouse sea level?- and what can we do about suggest that SO yr or so will not be long enough for it anyway? such adaptation. But is SO-yr the time scale for significant global change? There is certainly a growing body of opinion that reefs are generally showing signs of growing I suggest that we simply do not know how stress. It is, however, a still a strong tendency of patchy temperature increases will be, and we cer­ many scientists to resist these "conclusions." As it tainly know too little yet to predict the probability of becomes more fashionable to seek environmental generalised coral bleaching resulting from tempera­ problems, it is obvious that we will find them-or ture increase whether or not caused by global more importantly, report them. Thus the search for warming. "signs" is, by its very nature, self-fulfilling. The Is temperature the most common cause of considerable division of opinion on reef health is just bleaching? Certainly, the southern GBR has long as marked in Australia as elsewhere, with well experienced bleaching from extreme low tempera­ established reef scientists covering the whole spec­ ture in winter. Low salinity on the inner reef tract in trum of opinion. the GBR resulting from floods from hurricane Probably the most universally invoked stress for deluges causes spectacular bleaching. This bleaching reef systems of the world is nutrient build up in could easily and mistakenly be attributed to high inshore waters attributable to anthropogenic sources. temperature a few days later when the flood plume This has received considerable attention in the GBR, has cleared and hot, still monsoonal conditions have Florida, and the Caribbean. Yet it is probably the reestablished. most tenuously based of our serious concerns. Such Storms and Runoff: stress is likely to be even more severe throughout much of the SO% of the world's reefs occurring in SE Increased storminess and runoff are one of the Asia but unfortunately the hard evidence is very possible changes to be expected during Greenhouse poorly documented for that region. Even more climate change. The acute effects of these occurrences uncertain is the likelihood of Greenhouse enhance­ are obvious and quite well understood. Also we ment of nutrient build-up. Opinion is extremely know that recovery can be vigorous and rapid in the divided on whether significantly increased run-off best circumstances. But what if this damage occurs will be of other than very localised significance along on reefs already "sick" (i.e. subjected to appreciable tropical coasts. chronic anthropogenic stresses such as nutrient buildup and/or sediment runofO? We can then The Specific Matter of Bleaching: confidently predict a much less optimistic scenario. Particularly because of Peter Glynn's work with Will storms and runoff really increase appreciably in bleaching in Pacific Panama and elsewhere, it is clear the tropics during Greenhouse? On the basis of that bleaching can result from elevated temperature, present prediction, this seems only marginally likely and that this may result from el Nino events. But on a global scale, though it might be considerable in does this have anything to do with climate change? Is particular localised areas. bleaching really getting more common or are we just Stress Response: much more aware of it because of the efforts of such dedicated information collation networks as that of It is important always to bear in mind the subtle Bert Williams? How many of the bleaching events and synergistic ways in which stresses affect reef reported really correlate with elevated temperature? systems. Chronic stresses may be tolerated for very -and if they do, what reasons do we have to long periods of time with little outward sign. Acute correlate those particular warm water events with events cause obvious death and destruction but, in overall global warming? isolation, are likely to be followed by quite rapid

48 recovery. However, where an acute event occurs in • The Queensland Dept. of Primary Industries the presence of pre-existing and previously tolerated has initiated coordination of research effort chronic stresses, there may be an almost complete considering agricultural runoff failure to recover to the status of a normal reef • There is considerable concern from the ecosystei. agricultural chemicals industries Greenhouse Summary: • The GBRMPA has in place useful but still inadequate R&M programs Ove~all, it is my personal opinion that reefs will prove to be "well" enough to cope with Greenhouse • The GBRMP A has effective controls by I changes, •veraged out over the whole of the world's permit on direct discharges reefs. I believe that sea level rise will prove beneficial, What is the Immediate Need?: temperan!Jre increases will be tolerated and adapted to, and thbt storminess will not increase to the level There is an immediate and urgent need for the of becoming intolerable. The totally unanswered, and GBRMP A and the coral reef communities of the perhaps Jnanswerable, questions concern the extent world to initiate comprehensive, long-term programs to which ~e may expect local, extreme, and intoler­ of research to consider responses and trends in coral able anomalies in the overall climate change pattern. reefs to all aspects of environmental change and anthropogenic influence, both long and short term. It The GreJ Barrier Reef Marine Park Authority is totally unnecessary, and in fact very unwise to Positio'n: focus primarily on coral bleaching or long term We Jresently believe that the issue most likely climate change. to prove ~f greatest consequence to the long term What we need is: health of.~he GBR in the foreseeable future is that of nutrient ~uild-up. This is not because of any total • MONITORING, AND MORE MONITOR- confidence that there is conclusive evidence, but ING! because or the very well established perception that • on all spatial scales ther~. is a~oblem, and consequently a pressing need • on all time scales for its re .Jution. We believe that this stress, if proven to be real, is on a time scale which makes • and with very long term commitment overall eli te change of distinctly secondary In my opinion, the commitment to such moni­ significan to the Reef. toring programs can only be at a government/ government agency level as no individual scientist or Wha! we need to know as soon as possible is: arguably any university is in a position to consider or • ·Wha~ levels of nutrients and resulting administer such commitment. Notwithstanding the plankton etc are present? implied departure from the conventional principal I • What are the trends in these levels? investigator/peer review system, such global envi­ ronmental monitoring effort must have the support • Are ~ese levels and trends directly anthropo­ genic? of the significant scientists in the coral reef sciences. Ultimately the scientific community as a whole must • Wha~ are the likely effects of nutrient input benefit from the existence of the resulting long term on reefs? I data base. There is no other way we can ever expect • Are these effects already in evidence in the really to come to grips with the impact of environ­ GBR?I mental variability, climate change, or, in fact, the global significance of coral bleaching, than to have Obvi~msly, there is some knowledge from data extensive in time and space. Australia and elsewhere about each of these issues. However,:it is hopelessly inadequate. Initiatives are The Present Miami Workshop: being tak~ in Australia and we do see some hope for our information base in the reasonably near It is my hope to gain from this meeting a better future: perspective of the current global status of reef I problems; information which will be of value to me • Public awareness of a problem has greatly in helping to formulate management and research increased strategies for the Great Barrier Reef Marine Park; and • The farming sector is reacting with positive a commitment from the participants to the need for concern long term, world-wide monitoring programs fo­ • The ''Decade of Land Care" is serving as a cussed on all aspects of coral reefs in the context of very good umbrella environmental change.

49