11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 17: Emerging Techniques in Remote Sensing and Geospatial Analysis
17-1
Mapping Coral Reef Benthic Zones From High-Spatial Resolution Image
Segmentation And Photo Transect Data
Stuart PHINN* 1 , Chris ROELFSEMA 2 , Ian LEIPER 2 , Peter MUMBY 3
1 Geography, Planning and Architecture, University of Queensland, Brisbane, Australia,
2 University of Queensland, Brisbane, Australia, 3 University of Exeter, Exeter, United
Kingdom
The objective of this work was to test an approach for integrating field survey data and
high-spatial resolution satellite image data to map coral reef benthic zones. Commonly
accessible field survey techniques and image data sets were used to define map classes
based on statistical analysis of benthic cover features defined from field photos. Our
approach was applied to field survey data from georeferenced photo transects and a
coincident high spatial resolution Quickbird multi-spectral satellite image from Heron
Reef, southern Great Barrier Reef, Australia. The first stage identified benthic cover type
and percentage cover from 3592 geo-referenced benthic photos. In the second stage,
frequently recurring assemblages of benthic cover types were defined from discriminant
and cluster analyses of the geo-referenced photos. A label for each cluster was
determined from the mean percentage cover values of each major benthic-cover class for
all photo-points present in the resultant cluster. For the third stage, Definiens® image
segmentation was used to generate a multi-scale segmentation of the Quickbird image
into maps of reef features of a specific size. A final stage labelled the polygons at each of
the different scales of image segmentation. This was done by overlaying half of the
classified photo-points on the segmented image and developing training sites for labelling
reef zones. Next, the remaining set of labelled polygons was used to conduct a standard
error assessment. The output reef community zone map matched the validation data,
while each other scale corresponded to a repetitive collection of reef features, making up
“zones” which could be classified later according to communities or geomorphic features.
This work presents an example of an approach suitable for the spatial scale of high spatial
resolution satellite image data, the heterogeneous nature of coral reefs, and their regional
variation.
17-2
The Status Of The Millennium Coral Reef Mapping Project Worldwide
Serge ANDREFOUET* 1 , Christine KRANENBURG 2 , Damaris TORRES-PULLIZA 2 ,
Frank MULLER-KARGER 2,3
1 Institut de Recherche pour le Developpement, Noumea, New Caledonia, 2 College of
Marine Science, University of South FLorida, St Petersburg, FL, 3 Univ. Massachusetts
Dartmouth, New Bedford
The Millennium Coral Reef Mapping Project (MCRMP) is a unique program that uses
Landsat 7 satellite imagery to map the extent and diversity of coral reef worldwide at
geomorphological level. The project was supported by NASA and IRD. After the creation
of a suitable archive of Landsat images in 2004, a classification scheme was designed,
tested, updated and applied to all coral reef regions worldwide. In late 2006, the
definitive format for product distribution as GIS files was created in partnership with
WorldFish/Reefbase. Since 2004, GIS products result from mostly visual interpretation of
satellite images, and from automatic image classification procedures if reef types and
image qualities are suitable. Geomorphological layers are interpreted and labeled to
provide a first temporary product. Then, the validation process assigns a final label for
each polygon from a hierarchical typology of 800 different geomorphological classes,
and ensures the consistency between products from different areas. Landsat 7 data had to
be complemented by Landsat 5 and ASTER images in several areas due to persistent
cloud cover.
Products offer for the first time a thematically rich, spatially accurate and consistent
representation of all reef systems worldwide. Accurate statistics on the extent, diversity
and spatial structures of coral reefs are available as GIS files and regional atlases. This
information has been used by a variety of research and management projects that took
advantage of the hierarchical scheme to integrate the exact level of information needed.
The communication will take first the example of atolls worldwide as a model to describe
the different steps involved, from the Landsat image interpretation to the GIS products
and to different research and management applications. Then, an overview of the
different products, statistics and applications worldwide by nations will be presented.
17-3
Coral Reef Habitat Responses To Disturbance Events in Time: A Remote Sensing
Approach
Julie SCOPELITIS* 1 , Serge ANDREFOUET 2 , Stuart PHINN 1 , Pascale CHABANET 3 , Odile
NAIM 4 , Terry DONE 5
1 University of Queensland, Brisbane, Australia, 2 Institut de Recherche pour le Developement,
Noumea, New Caledonia, 3 Universite de la Reunion, Saint-Denis de la Reunion, Reunion,
4 Universite de Bretagne Sud, Vannes, France, Metropolitan, 5 Australian Institute of Marine
Science, Townsville, Australia
Coral reef monitoring programs documenting benthic changes over time seldom work at the
habitat scale. Our ability to predict post-disturbance habitat distributions can be improved by
combining historical in-situ monitoring data with remote sensing imagery, to provide maps of
temporal change. This study aimed to interpret habitat scale changes from high spatial
resolution imagery and in-situ data for three Indo-Pacific reefs (Abore Reef, New-Caledonia,
Saint-Leu Reef, Reunion Island, Heron Reef, Australia). The reefs were selected for their
different disturbance histories and recovery dynamics. A reef was considered as a mosaic of
habitats. A habitat was a hierarchical assemblage of geomorphology, substratum, coral cover
and growth form. High spatial resolution aerial photographs and satellite Quickbird images
were available for each site, as far back as 1973 for Saint-Leu. Field surveys were conducted in
2007 on each reef to create habitat typologies. Ten, eight and twenty habitats were characterized
on Abore, Heron and Saint-Leu respectively. This information, along with historical monitoring
data where available, was used to create multi-date habitat maps. Linking the map series to the
disturbance histories for each reef allowed us to interpret the habitat response and retrace the
history of the 2007 habitats. The maps revealed cyclone-induced reef degradation on Abore
(2002) and Saint-Leu (1989), with coral recovery on the latter by 1997. On Heron, coral
colonisation was observed across decades as channel dredging and bund wall constructions in
1965 increased the sea-level, altering reef flat hydrodynamics. This study showed that coral reef
response to disturbances can be retraced at the habitat scale using remote sensing imagery and
field data. This will be used to develop agent-based spatially-explicit models to help
management and monitoring site selection with predictive habitat maps under natural and
anthropogenic influences.
17-4
Combining The Benefits Of Satellite And in Situ Data To Determine Location And
Benthic Cover Of Patch Reefs in The Florida Keys
David PALANDRO* 1 , Melanie PETERS 1 , Luke MCEACHRON 1 , Michael CALLAHAN 1 , Jim
BURD 1
1 Florida Fish and Wildlife Research Institute, St. Petersburg, FL
The abundance of live coral cover has declined dramatically over the past three decades in the
Florida Keys. Research and monitoring in Florida has focused most of its effort on the offshore
platform reefs located seaward of Hawk Channel. Of the offshore reef sites monitored annually
by the Coral Reef Evaluation and Monitoring Project (CREMP), live coral cover averages less
than 4%. These reef sites were once covered with dense live coral cover, dominated by
Acropora palmata and A. cervicornis. Although much is known about the location and benthic
cover, including change over time, for the offshore reefs, comparatively little is known about
the patch reefs located in and around Hawk Channel. The ten patch reefs included in the
CREMP surveys average 14% stony coral cover. Here we used the synoptic coverage made
possible by IKONOS satellite imagery in conjunction with rapid in situ benthic ground-truthing
to produce a map for the Lower Keys, extending from Big Pine Key to the Marquesas Keys.
Specifically, we address the number, location, size and an estimate of live coral cover of patch
reefs. Initial results show approximately 2500 patch reefs, which were previously estimated at
420. Mean live coral cover is 17%, ranging from 0.3% to 52% and dominated by Montastraea
annularis and M. cavernosa. The high variability in live coal cover can only partially be
explained by their geographic location and overlying environmental parameters, which require
further detailed inquiry. The new findings provided by this study suggest that more effort may
be required to better understand the patch reefs in this area, which are now home to the
dominant abundance of live coral in the region.
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