CORDIO Status Report 2000

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dives, this study has demonstrated that this reef system possesses the capacity to recolonise degraded reefs, through a supply of coral planulae from surviving colonies. ACKNOWLEDGEMENTS This research was funded by the Cordio programme. I would like to thank Mr Ahmed Hafiz, Director of the Marine Research Centre and all of his staff who assisted with this work, particularly Mr Hussein Zahir. REFERENCES Bak, R.P.M. & Engel, M.S. 1979. Distribution, abundance, survival of juvenile hermatypic corals (Scleactinia) and the importance of life history strategies in the parent community. Mar. Biol. 54: 341-352. Birkeland, C. 1977. The importance of rate of biomass accumulation in early successional stages of benthic communities to the survival of coral recruits. Proc. 3 rd Int. Coral Reef Symp. 1: 15-21. Edwards, A.J., Clark, S., Zahir, H., Rajasuriya, A. & Rubens, J. Coral bleaching and mortality on artificial and natural reefs in the Maldives in 1998, SST anomalies and initial recovery. (submitted to Mar. Ecol. Prog. Ser.). Fairfull, S.J.L. &Harriot, V.J. 1999. Succession, space and coral recruitment in a subtropical fouling community. Mar. Freshwater Res. 50: 235-242. Hughes, T.P., Baird, A.H., Dinsdale, E.A., Moltschaniwskyj, N.A., Pratchett, M.S. Tanner, J.E. & Willis, B.L. 1999. Patterns of recruitment and abundance or corals along the Great Barrier Reef. Nature 397: 59-63. McClanahan, T. (in press). Damage and recovery potential of Maldivian coral reefs. Mar. Poll. Bull. Mumby, P.J. 1999. Bleaching and hurricane disturbances to populations of coral recruits in Belize. Mar. Ecol. Prog. Ser. 190: 27-35. Naeem, I., Rasheed, A., Zuhair, M & Riyaz, M. 1998. Coral bleaching in the Maldives –1998. Survey carried out in the North and South Malé atolls. 14p. Nazali, L. M., Johnstone, R.W. & Mgaya, Y.D. 1998. Factors affecting scleractinian coral recruitment on a nearshore reef in Tanzania. Ambio 27: 717- 722. Rajasuriya, A., Maniku, M.H., Subramanian, B.R. & Rubens, J. 1999. Coral Reef Ecosystems in South Asia. In: Linden, O. & Sporrong, N. 1999 (eds.) Coral Reef Degradation in the Indian Ocean, <strong>CORDIO</strong> & SAREC. pp.11-24. Rogers, C. 1984. Scleractinian coral recruitment patterns at Salt River Canyon, St. Croix, U.S. Virgin Islands. Coral Reefs 3: 69-76. Sier, C.J.S. & Olive, P.J.W. 1994 Reproduction and reproductive variability in the coral Pocillopora verrucosa in the Maldives. Mar. Biol. 118:713- 722. Wilkinson, C., Lindén, O., Cesar, H., Hodgson, G., Rubens, J. & Strong, A. 1999. Ecological and socio-economic impacts of 1998 coral mortality in the Indian Ocean: an ENSO impact and a warning of future change. Ambio 28: 188-196. Zahir, H., Naeem, I., Rasheed, A. & Haleem, I. 1998. Reef Check Maldives: Reef Check 1997and 1998. Marine Research Section, Ministry of Fisheries, Agriculture and Marine Resources, Republic of Maldives. – 175 –
Studies of bioerosion on coral reefs of Tanzania HELENA STRÖMBERG Zoology Department, Stockholm University, Stockholm, Sweden INTRODUCTION Responses of coral reef ecosystems to disturbance Historically, coral reefs have been subjected to a range of disturbances including major sedimentary events from flooded rivers (Robertson & Lee Long, 1990), storm events and changes related to long-term patterns such as El Niño (Glynn, 1985). Reef ecologists have accumulated a great deal of evidence implicating disturbance as a major influence on reef ecology (Connell, 1978). Increasing global temperatures, eutrophication in coastal areas and the physical damage that is becoming so widespread is potentially reducing the reefs intrinsic ability to cope with such perturbations. Primary production on a reef is largely dependent on a variety of algae including the symbiotic algae living in hard corals (zooxanthellae). The level of production that any of these components might attain is determined by a variety of physico-chemical (e.g. hydrodynamics and nutrients) and biological factors (e.g. grazer-communities). Furthermore, the addition of nutrients such as nitrogen and phosphorous has the potential to increase the growth rates of some algae and heterotrophic invertebrates relative to corals (Littler et al., 1991; Sammarco & Risk, 1990). As a consequence, many reef ecologists warn that eutrophication of waters surrounding coral reefs may alter patterns of dominance on these reefs from corals to various forms of fleshy and filamentous algae and bioeroding sponges (Rose & Risk, 1985; Sammarco & Risk, 1990). In practice, however, there are a number of factors that prevent this from occurring. Perhaps the most important is herbivory (Hatcher & Larkum, 1983). Vertebrates and invertebrates comprising the grazing community consume the plant production (Hatcher & Larkum, 1983) and often inadvertently ingest limestone from the skeletons of corals and epiphytic micro-invertebrates while grazing. Some investigators have argued that the abundance of grazers is the main limitation to primary production on coral reefs (Larkum & Steven, 1994). Indeed, the abundance of fleshy algae is generally very low on healthy reefs that support reasonable populations of herbivores. However, declines in grazing pressure through overexploitation of herbivorous fauna can shift the balance in favour of the algae allowing them to out-compete and eventually exclude corals from the reef community. The products of photosynthesis by zooxanthellae are the primary source of energy used by corals for accretion of calcium carbonate (CaCO 3 ) and skeletal growth (Muscatine, 1990). Mass bleaching on the scale reported in 1998 can alter the balance between net accretion and net decay of CaCO 3 from the reef framework. Subsequently, the loss of zooxanthellae through bleaching can reduce the rate of accretion of CaCO 3 into the skeleton of the coral. This imbalance may also be mediated by grazers, bioeroders and organisms whose actions directly affect benthic community structure (Done et al., 1996). The persistence of a coral reef, in the long-term, requires that its overall rate of calcium accretion equals or exceeds losses from biological and physical erosion and transport of sediment away from the reefs (Done et al., 1996). – 176 –
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CORAL REEF DEGRADATION IN THE INDIA
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Foreword The temperatures of the wo
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Address by the Global Coral Reef Mo
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Table of contents FORWARD 3 ADDRESS
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Executive Summary The World Conserv
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to date. Working group discussions
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Biophysical Generally, region-wide
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species exhibit different tolerance
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er-term, “shifting baselines” i
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flow diagram presented below. CORDI
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SECTION I Status Reports - 21 -
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East Africa - Summary DAVID OBURA C
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Kenya, reef status and ecology DAVI
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BENTHIC COMMUNITIES Benthic communi
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Figure 2. Three strategies for blea
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% cover % cover 16 14 12 10 8 6 4 2
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Table 3: Population densities and s
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Assessment of coral reef degradatio
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Table 1. Reef stations surveyed in
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live coral cover for Mbudya Marine
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Table 5. Some environmental paramet
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Coral reef monitoring and managemen
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L impopo Maputo Sa ve River Riv er
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category) and size classes (total n
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The status of South African coral r
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South Asia - Summary DAN WILHELMSSO
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SRI LANKA Most shallow coral reef h
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corals in Sri Lanka is relatively h
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Figure 1. Distribution of coral ree
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Kandakuliya Most of the nearshore r
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shallow water (0 m - 3 m) on the re
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Rajasuriya, A & De Silva, M.W.R.N.
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In each of these regions three reef
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Table 4. Summary data from transect
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The status of the coral reefs of In
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Relative importance in total landin
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Small pelagics Large pelagics Demer
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Indian Ocean Islands - Summary SUSI
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The reefs of the granitic islands o
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onies damaged was recorded using th
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FAMILY GENUS SPECIES DEAD SURVIVING
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FAMILY GENUS SPECIES DEAD SURVIVING
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Figure 10. Recruit on consolidated
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Reef systems of the islands of the
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Figure 2. Coral condition by locati
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At the Bank’s northern and southe
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chelles (Turner et al., this volume
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the shallow bays of Balaclava Marin
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Development of a geographical infor
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2 1,8 1,6 Mean Bleaching Score 1,4
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Meteorological data from the period
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Figure 16. Total sunshine (hrs) per
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solar irradiance. In Thailand, loca
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Harriott, V.J. 1985. Mortality rate
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Table 1. Location of CORDIO monitor
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Figure 1. Recovery from settlement
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that due to its low impact, dead co
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Map of the Western Indian Ocean wit
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In April 1998, close to the peak of
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Pachyseris, Turbinaria spp.) and en
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Partial mortality of Favites flexuo
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REFERENCES Barnes, J., Bellamy, D.J
Page 126 and 127: SECTION II Environmental Monitoring
Page 128 and 129: Sea surface temperature in the west
Page 130 and 131: Temperature and water exchange in a
Page 132 and 133: Figure 2a. Time series temperature
Page 134 and 135: ACKNOWLEDGEMENTS I would like to th
Page 136 and 137: Figure 2. Settlement plates for cor
Page 138 and 139: REFERENCES CARICOMP. 1994. Manual o
Page 140 and 141: Figure 2. Two possible recoveries f
Page 142 and 143: SECTION III Thematic/Research Repor
Page 144 and 145: Socio-economic assessment of the im
Page 146 and 147: to escape predation (Williams, 1991
Page 148 and 149: Table 4 Demersal fish landings in 1
Page 150 and 151: mersal species have not been heavil
Page 152 and 153: Therefore, it must be concluded tha
Page 154 and 155: ▲ Level of importance 35 30 25 20
Page 156 and 157: very few come specifically for reef
Page 158 and 159: Percentage 28% Food and beverages w
Page 160 and 161: Anonymous. 1998b. Basic Fisheries S
Page 162 and 163: has a 4 m tidal range) dominated by
Page 164 and 165: Table 1. Comparison of the gross be
Page 166 and 167: Greenstein, B.J., Curran, H.A. & Po
Page 168 and 169: to assess ciguatera risk by impleme
Page 170 and 171: Evaluation of succession and coral
Page 172 and 173: within each depth zone (5 m and 10
Page 174 and 175: The taxonomic patterns of coral rec
Page 178 and 179: Bioerosive processes An important a
Page 180 and 181: each of the three different fish co
Page 182 and 183: Figure 1. Coral fragments transplan
Page 184 and 185: Pavona Echinopora 50 100 50 100 Gro
Page 186 and 187: A low-tech method for reef rehabili
Page 188 and 189: Impacts of bleaching on coral commu
Page 190 and 191: anching and massive corals (Plate 1
Page 192 and 193: es, metal bars and PVC surfaces. No
Page 194 and 195: strate that supports a low percenta
Page 196 and 197: egeneration and prevent further des
Page 198 and 199: APPENDICES - 197 -
Page 200 and 201: Coral Reef Degradation in the India
Page 202 and 203: LIST OF PARTICIPANTS LIONEL BIGOT A
Page 204 and 205: AGNETHA NILSSON Programme Officer U
Page 206 and 207: DR. SUE WELLS Co-ordinator, E.A. Ma
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