Advertisement

Coral Reefs

, Volume 23, Issue 1, pp 161–168 | Cite as

Inventory of the Maldives’ coral reefs using morphometrics generated from Landsat ETM+ imagery

Report

Abstract

In this study, we present exact measures of the number, area, and basic morphometric statistics for every single reef of the Maldivian archipelago, as derived from the interpretation of remotely sensed data collected by the Landsat-7 ETM+ earth-observing satellite sensor. We classified and mapped seven morphological attributes of reefs (six marine habitats and reef-top islands) to 30-m depth at 30×30 m spatial resolution (pixel size) for the entire archipelago. The total archipelagic area (all coral reef and lagoon habitats) of the 16 atolls, five oceanic faros, and four oceanic platform reefs which comprise the Maldives is 21,372.72±1,068.64 km2 (approx. 20% of the Maldives’ Territorial Sea). A total of 2,041±10 distinct coral reef structures larger than 0.01 km2 occur in the Maldives, covering an area of 4,493.85 km2 (including enclosed reef lagoons and islands) to 30-m depth. Smaller areas of coral reef substratum cover another 19.29 km2, bringing the total area of Maldivian coral reefs to 4,513.14±225.65 km2. Shallow coral platforms thus occupy 21.1% of the total area of the archipelago (0.0052% of the EEZ area of the Maldives). Of these reefs, 538 are rim and oceanic reefs, covering 3,701.93 km2 (82.5% of the total reef area), and 1,503 are patch reefs within the atoll lagoons, covering 791.92 km2 (17.5% of the total reef area). Islands occupy only 5.1% of the total reef area. Mapping the Maldives’ coral reefs at high spatial resolution is only possible with remote sensing and spatial analysis technologies. These greatly reduce the large uncertainty around current estimates of reef area. Our accurate measure of total reef area is only 50.6% of the current best estimate, a result having significant implications for predictions of the Maldives’ reef productivity and response to global climate change. Here we present current best practice and compare the methods and measures with previous approaches.

Keywords

Maldives Coral reef area Remote sensing Geographic information system 

Notes

Acknowledgements

We appreciate the inclusion and scheduling of Landsat-7 ETM+ images of the Maldives by the NASA Long Term data Acquisition Program (LTAP), and acknowledge the provision of six images by Serge Andréfouët through the Institute for Marine Remote Sensing at the University of South Florida. Serge also provided advice on protocols for reef classification using satellite imagery, for which we are very grateful. We thank the staff of the Ministry of Fisheries, Agriculture and Marine Resources, Government of the Maldives, and Canadian Fishery Consultants Ltd. for supporting the ground-truthing expedition. Funding for A. Naseer’s work was obtained from the Canadian Commonwealth Scholarship Fund. Partial support for B.G. Hatcher’s involvement was provided by the National Science and Engineering Research Council of Canada, Dalhousie University, and Canadian Fishery Consultants Ltd.

References

  1. Agassiz A (1903) An expedition to the Maldives. Am J Sci Ser 4 76:297–308Google Scholar
  2. Andréfouët S, Claereboudt M, Matsakis P, Pages J, Dufour P (2001) Typology of atoll rims in Tuamotu Archipelago (French Polynesia) at landscape scale using SPOT images. Int J Remote Sensing 22:987–1004CrossRefGoogle Scholar
  3. Arvidson T, Gasch J, Goward SN (2001) “Landsat 7’s long term acquisition plan—an innovative approach to building a global imagery archive. Remote Sensing Environ 78:13–26CrossRefGoogle Scholar
  4. Bianchi CN, Colantoni P, Geister J, Morri C (1997) Reef geomorphology, sediments and ecological zonation at Felidhu Atoll, Maldive Islands, (Indian Ocean). In: Proc 8th Int Coral Reef Symp 1:431–436Google Scholar
  5. British Hydrographic Office (1993) Admiralty charts, Maldives sheets, Indian Ocean #1011, #1012, #1013, #1014, scale 1:300,000. Taunton, UKGoogle Scholar
  6. Collins LB, Zhu ZZ, Wyrwoll KH, Hatcher BG, Playford PE, Chen J, Eisenhauer A, Wasserburg G (1993) Late Quaternary evolution of high latitude reefs on a cool-water carbonate margin: the Houtman Abrolhos carbonate platforms, southwest Australia. Mar Geol 110:203–212CrossRefGoogle Scholar
  7. Crapper PF (1980) Errors incurred in estimating an area of uniform land cover using Landsat. Photogr Eng Remote Sensing 46:1295–1301Google Scholar
  8. Crossland CJ, Hatcher BG, Smith SV (1991) Role of coral reefs in global ocean production. Coral Reefs 10:55–64Google Scholar
  9. Daly RA (1915) The glacial control theory of coral reefs. Proc Acad Arts Sci 51:155–251Google Scholar
  10. Darwin C (1842) The structure and distribution of coral reefs. Smith, Elder and Co., London, UKGoogle Scholar
  11. Dumbraveanu D, Sheppard CRC (1999) Areas of substrate at different depths in Chagos Archipelago. In: Sheppard CRC, Seaward MRD (eds) Ecology of the Chagos Archipelago, pp 35–44Google Scholar
  12. Fagerstrom JA (1987) The evolution of reef communities. Wiley, New YorkGoogle Scholar
  13. Gardiner JS (1902) The formation of Maldives. Geogr J 19:277–301Google Scholar
  14. Gasch J, Arvidson T, Goward SN, Andréfouët S, Hu C, Müller-Karger FE (2000) An assessment of Landsat 7/ETM+ coverage of coral reefs worldwide. In: Proc IGARSS 2000. IEEE, Honolulu, Hawaii, pp TU-14–11Google Scholar
  15. Green EP, Mumby PJ, Edwards AJ, Clark CD (2000) Remote sensing handbook for tropical coastal management. UNESCO, ParisGoogle Scholar
  16. Hatcher BG (2001) A framework for the classification of benthic communities of the Scotian Shelf for the maintenance of the diversity of the marine ecosystem. Final Report to Fish & Oceans Canada, Bedford Inst Oceanogr, Dartmouth, Nova ScotiaGoogle Scholar
  17. Hatcher BG, Imberger J, Smith SV (1987) Scaling analysis of coral reef systems: an approach to problems of scale. Coral Reefs 5:171–181Google Scholar
  18. Kleypas JA (1997) Modeled estimates of coral reef habitat and carbonate production since the last glaciation. Paleoceanography 12:533–545CrossRefGoogle Scholar
  19. Kleypas JA, Buddemeier RW, Gattuso J-P (2001) The future of coral reefs in an age of global change. Int J Earth Sci 90:426–437Google Scholar
  20. Mumby PJ, Green EP, Edwads AJ, Clark CD (1999) The cost-effectiveness of remote sensing for tropical coastal resources assessment and management. J Environ Manage 3:157–166CrossRefGoogle Scholar
  21. Naseer A (2003) The integrated growth response of coral reef to environmental forcing: morphometric analysis of coral reefs of the Maldives. PhD Dissertation, Department of Biology, Dalhousie University, Halifax, NSGoogle Scholar
  22. Naseer A, Hatcher BG (2001) Assessing the integrated growth response of coral reefs to monsoon forcing using morphometric analysis of reefs in Maldives. In: Proc 9th Int Coral Reef Symp 1:75–80Google Scholar
  23. Oliver J, Noordeloos M (eds) (2002) ReefBase: a global information system on coral reefs. World Wide Web electronic publication http://www.reefbase.org, accessed 28 February 2003
  24. Possingham H, Ball I, Andelman S (2000) Mathematical methods for identifying representative reserve networks. In: Ferson S, Burgmnan MA (eds) Quantitative methods in conservation biology. Springer, Berlin Heidelberg New YorkGoogle Scholar
  25. Purdy EG, Bertram GT (1993) Carbonate concepts from the Maldives, Indian Ocean. AAPG Stud Geol 34:1–56Google Scholar
  26. Pyle RL (2001) Assessing undiscovered fish biodiversity on deep coral reefs using advanced self-contained diving technology. Mar Technol Soc J 34:82–91Google Scholar
  27. Rajasuriya AH, Zahir EV, Muely BR, Subramanian K, Venkataraman MVM, Wafar SM, Munjurul Hannan Khan, Whittingham E (2000) Status of coral reefs in South Asia: Bangladesh, India, Maldives and Sri Lanka. In: Wilkinson C (ed) Status of coral reefs of the world: 2000. Aust Inst Mar Sci, Townsville, pp 95–116, http://www.reefbase.org/references/ref_Literature.asp?searchactive=yes&ID=11755
  28. Risk MJ, Sluka R (2000) The Maldives: a nation of atolls. In: McClanahan TR, Sheppard CRC, Obura DO (eds) Coral reefs of the Indian Ocean, Oxford University Press, UK, pp 325–351Google Scholar
  29. Sewell RBS (1932) The coral coasts of India. Geogr J 79:449–65Google Scholar
  30. Smith SV (1978) Coral-reef area and the contributions of reef to processes and resources of the world’s oceans. Nature 273:225–226Google Scholar
  31. Spalding MD, Grenfell AM (1997) New estimates of global and regional reef areas. Coral Reefs 16:225–230CrossRefGoogle Scholar
  32. Spalding MD, Ravilious C, Green EP (2001) World atlas of coral reefs. Prepared at UNEP World Conservation Monitoring Centre. University of California Press, Berkeley, USAGoogle Scholar
  33. Spray WA (1966) Surveying and charting the Indian Ocean, the British contribution 1750–1838, chap 10, “The Arabian Sea, the Maldives and vicinity”. Thesis, University of London, UKGoogle Scholar
  34. Stoddart DR (1965) The shape of atolls. Mar Geol 3:369–383CrossRefGoogle Scholar
  35. Vecsei A (2001) Fore-reef carbonate production; development of a regional census-based method and first estimates. Palaeogeogr Palaeoclimatol Palaeoecol 175:185–200CrossRefGoogle Scholar
  36. Wells S (1988) Maldives. In: Wells S (ed) Coral reefs of the world, vol 2, Indian Ocean, Red Sea and Gulf. Int Union Conserv Nature, Switzerland, pp 191–203Google Scholar
  37. Woodroffe CD (1992) Morphology and evolution of reef islands in the Maldives. In: Proc 7th Int Coral Reef Symp 2:1217–1225Google Scholar

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  1. 1.Department of BiologyDalhousie UniversityHalifaxCanada
  2. 2.Marine Affairs ProgramDalhousie UniversityHalifaxCanada
  3. 3.Marine Research CenterH. White WavesMaléMaldives

Personalised recommendations