Changes of coral communities over 35 years: Integrating in situ and remote-sensing data on Saint-Leu reef (la Reunion, Indian Ocean)

Scopelitis, J., Andrefouet, S., Phinn, S., Chabanet, P., Naim, O., Tourrand, C. and Done, T. (2009) Changes of coral communities over 35 years: Integrating in situ and remote-sensing data on Saint-Leu reef (la Reunion, Indian Ocean). Estuarine, Coastal and Shelf Science, 84 3: 342-352. doi:10.1016/j.ecss.2009.04.030


Author Scopelitis, J.
Andrefouet, S.
Phinn, S.
Chabanet, P.
Naim, O.
Tourrand, C.
Done, T.
Title Changes of coral communities over 35 years: Integrating in situ and remote-sensing data on Saint-Leu reef (la Reunion, Indian Ocean)
Journal name Estuarine, Coastal and Shelf Science   Check publisher's open access policy
ISSN 0272-7714
1096-0015
Publication date 2009-09-20
Year available 2009
Sub-type Article (original research)
DOI 10.1016/j.ecss.2009.04.030
Volume 84
Issue 3
Start page 342
End page 352
Total pages 11
Place of publication London, United Kingdom
Publisher Academic Press
Collection year 2010
Language eng
Subject 090905 Photogrammetry and Remote Sensing
970105 Expanding Knowledge in the Environmental Sciences
Abstract Monitoring coral reef communities at a decadal scale is necessary to understand and project their dynamics to provide a basis for reef management in light of disturbances and climate change. Complementing infrequent and localised in situ observations, time-series of aerial photographs and remotely sensed satellite images provide a means of monitoring the position and extent of reef-top coral communities, vegetation and abiotic substrata at the whole reef scale. The aim of the present study was to map such changes on Saint-Leu Reef (La Réunion) between 1973 and 2007. The period included two cyclones (1989, 2002) and one severe bleaching event (2002). Vertical images of the reef were recorded in five aerial photographs (1973, 1978, 1989, 1997, and 2003) and two Quickbird satellite images (2002, 2006) during that time. Quantitative in situ observations of parts of the reef-top were also available both to document ecological and substratum characteristics that produce the color and texture observable in the photos and satellite images. Coral communities were mapped on all images using manual delineation of polygons identified according to color and texture contrast. The 2006 Quickbird image was used as the mapping base and 15 types of coral communities were identified from a reef survey conducted in 2007. This hierarchical typology used coral growth forms, live and dead coral cover, macro-algae, substratum (sand, rubble and platform) and, to a lesser extent, coral taxonomy. The polygons at date t were over-laid onto image t - 1 across the whole series and their boundaries were manually edited to match the pattern on the earlier image. Labelling of polygons was guided by field-survey data and maps. For coral-dominated patches, six successive pairs of maps from 1973 to 2006 were compared to produce 'coral community change maps' for that period. Despite the multiple disturbance events, the coral community distribution and composition in 2006 on Saint-Leu Reef did not display major differences compared to 1973. This suggests a high degree of coral resilience at the site, led by rapid recovery of compact branching corals. The mapping techniques overcame challenges due to different image quality and the sparsity of in situ observations in time and space. Our results demonstrate the potential for further application of reef monitoring protocols based on complementary in situ and remote-sensing data to help understand the dynamics of reef-top coral reef communities and geomorphology over years to decades.
Keyword Aerial photographs
Bleaching
Change detection
Coral reefs
Cyclones
Ecosystem resilience
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online 7 May 2009.

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Geography, Planning and Environmental Management Publications
2010 Higher Education Research Data Collection
 
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Created: Fri, 19 Mar 2010, 14:19:45 EST by Helen Smith on behalf of School of Geography, Planning & Env Management