Oliver et al (2004) Monitoring bleaching

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A GLOBAL PROTOCOL FOR ASSESSMENT AND MONITORING OF CORAL BLEACHING ..........................................................................................................................................................1 INTRODUCTION..................................................................................................................................................3 WHY IS A PROTOCOL NEEDED? ................................................................................................................4 WHO WILL USE THE PROTOCOL?.........................................................................................................................4 HOW SHOULD THE PROTOCOL BE USED?............................................................................................................5 QUICK GUIDE – START HERE......................................................................................................................5 HOW DO I IDENTIFY CORAL BLEACHING?..........................................................................................................5 HOW DO I MEASURE OR QUANTIFY CORAL BLEACHING?.................................................................................6 THE NOAA/REEFBASE BLEACHING QUESTIONNAIRE....................................................................................7 WHAT DO I DO IF I SEE BLEACHING? ..................................................................................................................7 DESIGNING A PROGRAM FOR YOUR NEEDS .......................................................................................8 TYPICAL QUESTIONS/OBJECTIVES......................................................................................................................8 MONITORING FOR DIFFERENT SCENARIOS......................................................................................................11 OUTLINE OF A TYPICAL MONITORING PLAN....................................................................................................11 SAMPLING DESIGN CONSIDERATIONS..............................................................................................................12 MONITORING PROCEDURES...............................................................................................................................15 DATA MANAGEMENT ................................................................................................................................... 23 LITERATURE ..................................................................................................................................................... 23 APPENDICES ...................................................................................................................................................... 25 APPENDIX 1. DATA FORMS................................................................................................................................25 APPENDIX 2. MONITORING VARIABLES...........................................................................................................28 APPENDIX 3. VARIABLE CODES.........................................................................................................................31 APPENDIX 4..........................................................................................................................................................36 2
Introduction Coral bleaching occurs when corals lose the single celled algae (zooxanthellae) which live within their tissues. These golden brown coloured algae (Figure 1) occur in varying densities in reef corals (and other reef invertebrates), and give them a light tan to deep chocolate brown colour. Where additional pigments exist within the animal cells, this brown colour can be overlain by different additional hues such as blue, green, purple or yellow (Figure 2). When corals lose their zooxanthellae, the white skeleton can be seen through the transparent animal tissue, making the corals looked bleached white. In cases where the corals possess additional animal pigments, bleached corals take on vivid fluorescent hues, with no trace of the normal brown background colour (Figure 3). Corals which have bleached are not dead. On close inspection it is possible to see the transparent polyps and tentacles of bleached colonies. However corals cannot remain bleached indefinitely. If the stress is not too severe or prolonged, stressed colonies can slowly regain their zooxanthellae and survive. But in severe bleaching events many corals subsequently die, casing major changes to the structure and function of the reef ecosystem, and possible cascading impacts on other organisms. Although bleaching in individual corals was first observed early in this century, massive events affecting reefs spanning tens to hundreds of kilometres have only been documented in the last two decades . In the laboratory, or on a small scale in the field, bleaching has been attributed to a number of factors which cause stress, including extremes (both high and low) of temperature and light, low salinity, low oxygen, high concentration of toxic chemicals which affect respiration and photosynthesis. In the case of “mass coral bleaching” involving a range of coral species over large areas, elevated temperatures are the primary stress factor (Coles & Brown, 2003; Hoegh-Guldberg 1999). Elevated sea temperatures may be driven by regional phenomena (such as El Niño events), but local conditions, such as periods of calm weather and clear skies, also play a major role in determining sea temperatures in reefal regions. Decreased salinity from excessive rainfall and flood plumes can increase the amount of bleaching, and may be a primary cause in some situations (mostly over limited spatial scales). During the worst global bleaching event in 1998, more than 680 records of coral bleaching were reported from over 55 different reef regions. Many of the affected reefs suffered massive mortality from which they are still recovering (Wilkinson 2002). This event was also the most intensively studied, and satellite data showing thermal anomalies or “hot spots” clearly showed that large patterns of abnormally and consistently high temperature were very well correlated with bleaching patterns, and in some cases appeared to be able to predict the events (Toscano et al. 2000, Wilkinson et al 1999). Coral bleaching is now considered to be one of the most significant and widespread threats to coral reefs Hughes et al., 2003). When predicted temperature increases due to global warming over the next 100 years have been compared to the known temperature bleaching limits of corals, the depressing conclusion is that by 2020 coral reefs in many parts of the world may suffer bleaching and mortality every year Hoegh-Guldberg, 1999). Unless corals are able to adapt to raising temperatures, reefs may suffer progressive deterioration and species loss, resulting in major ecological impacts and consequent social and economic impacts on the human communities in many countries that depend on reefs for their livelihoods. Global warming and greenhouse gas emission thus represent a relatively new and severe threat to the sustainability and productivity of coral reefs and the services that that provide to humans (Hughes et al., 2003; Wellington et al., 2001; Cesar et al., 2003). There is an urgent need to obtain better information on bleaching events around the world. This information is crucial to scientific understanding of the fate of coral reefs and to the feasibility and practicality of developing management strategies to increase the resistance and resilience of reefs to bleaching and associated mortality events. This protocol aims to provide a simple yet consistent set of procedures to: 1. Document the spatial dis tribution, timing and severity of large scale bleaching events and how they compare with maps of global temperature anomalies and other meteorological and oceanographic factors. This will help in the developing and testing of predictive models of bleaching which can focus attention on susceptible reefs which might benefit from better 3
Page 1: Draft A Global Protocol for Assessm
Page 5 and 6: This protocol is designed to assist
Page 7 and 8: and easily, even if only part of so
Page 9 and 10: which has very poor power to answer
Page 11 and 12: Monitoring for different scenarios
Page 13 and 14: Sites within a Location Locations w
Page 15 and 16: • The initially random selection
Page 17 and 18: Recommended Manta Tows The manta to
Page 19 and 20: Anchor damage: Pictures: Comments:
Page 21 and 22: Buddy: Vessel: Depth: Replicate: Be
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