Coral Reef Distribution, Status and Geomorphology-Biodiversity
Total Page：16
File Type：pdf, Size：1020Kb
Coral Reefs (2005) 24: 31–42 DOI 10.1007/s00338-004-0444-4 REPORT Serge Andre´foue¨t Æ Hector M. Guzman Coral reef distribution, status and geomorphology–biodiversity relationship in Kuna Yala (San Blas) archipelago, Caribbean Panama Received: 17 March 2003 / Accepted: 15 September 2004 / Published online: 30 December 2004 Ó Springer-Verlag 2004 Abstract Most of the knowledge of the reef geomor- suggest that habitat heterogeneity within geomorpho- phology and benthic communities of Kuna Yala coral logical areas explain better the patterns of coral diver- reefs (Caribbean Panama) comes from the western side sity. This study confirms the potential of combined of the archipelago, a few tens of kilometers around remote sensing and in situ surveys for regional scale Punta San Blas (Porvenir). To bridge the gap between assessment, and we suggest that similar approaches Porvenir and the Colombia–Panama border, we inves- should be generalized for reef mapping and assessment tigated with Landsat images the extent and geomor- for other reef sites. phological diversity of the entire Kuna Yala to provide geomorphologic maps of the archipelago in 12 classes. Keywords Landsat Æ Remote sensing Æ In addition to remote sensing data, in situ survey con- Geomorphology Æ Mapping Æ San Blas Æ ducted in May–June 2001 provided a Kuna Yala-wide Coral reef diversity first synoptic vision of reef status, in terms of benthic diversity (number of species of coral, octocorals, and sponges) and reef health (coral versus algal cover). For a total reef system estimated to cover 638 km2 along Introduction 480 km of coastline, 195 km2 include coral dominated 2 areas and only 35 km can be considered covered by Coral reefs of Kuna Yala (San Blas) archipelago corals. A total of 69 scleractinian coral, 38 octocoral, (Fig. 1), Republic of Panama, have been studied for and 82 sponge species were recorded on the outer slopes several decades (Porter 1974) . However, most of the of reef formations, with a slightly higher diversity in the knowledge of reef geomorphology and benthic and fish area presenting the most abundant and diverse reef communities comes from the western reefs of the formations (western Kuna Yala). Attempts to relate archipelago (Dahl et al. 1974; Lessios et al. 1984; Lasker benthic diversity and geomorphological diversity pro- et al. 1984; Ogden and Ogden 1993; Shulman and vided only weak relationships regardless of the taxa, and Robertson 1996; Clifton et al. 1997; Macintyre et al. 2001), few tens kilometers around Punta San Blas (or Communicated by Geological Editor P.K. Swart Porvenir). As a consequence, there are serious gaps in knowledge of coral reef ecosystem extent, type of S. Andre´foue¨ t(&) structure, benthic diversity and reef health throughout Institute for Marine Remote Sensing, the entire archipelago which stretches along 480 km of University of South Florida—College of Marine Science, 140, 7th Av. South, St Petersburg, FL 33701, USA coastline from Punta Porvenir till the Columbia–Pan- E-mail: [email protected], [email protected] ama border. Tel.: +1-727-5533987/+1-687-26-0800 Recently, Guzman et al. (2003) reported on the Fax: +1-727-5531186/+1-687-26-4326 consequences of mining in coral communities by indig- H. M. Guzman enous Kuna people and the status of coral reef com- Smithsonian Tropical Research Institute, munities in Kuna Yala. Since 1938, Kuna people have Unit 0948, APO AA, 34002-0948, USA autonomy and authority within the boundaries of Kuna E-mail: [email protected] Tel.: +1-507-2128733 Yala, their territory, which includes the islands and reefs Fax: +1-507-2128790 of Kuna Yala archipelago. Demographic growth and limited space on reef-top islands resulted in extensive Present address: S. Andre´foue¨ t UR Coreus—Institut de Recherche pour le De´veloppement (IRD), coral mining to create new land. Guzma´n et al. (2003) BP A5, 98848 Noume´a cedex, New Caledonia investigated the present situation in terms of living coral 32 occurred mostly in Terra Incognita territory and during a limited time, several high-resolution Landsat images were used to plan the survey. In parallel with the benthic quantitative assessment, the images were also used to explore, survey, characterize, and inventory the different types of reef and island geomorphological formations. The multi-scale observations collected in 2001 allows us to present for the first time a complete overview of Kuna Yala reefs in terms of reef structures, reef extent, coral reef health, and coral diversity hot spots. The creation of habitat or geomorphology maps is a critical step towards the assessment and management of reef ecosystems. Current applications of coral reef hab- itat maps include biogeochemical budgets (Andre´foue¨ t and Payri 2001) or resource assessment and exploitation planning (Long et al. 1993; Andre´foue¨ t et al. 2004). An interesting new application is to use remotely sensed habitat maps as indirect guides for assessing biological diversity in the context of marine conservation, or to identify the scale of processes that controls the structure of a mosaic of habitats (Mumby 2001). For marine conservation, the main goal is to predict the distribution of biodiversity in remote coral reef regions; and how this distribution can be inferred indirectly from broad-scale spatial patterns to avoid costly detailed surveys at the species level (Gaston 2000; Turner et al. 2003). Several examples of this approach already exist for coral reef environments, conducted at various spatial scales. However, in previous coral reef studies investigating diversity and spatial patterns (e.g., Galzin et al. 1994; Fabricius and De’ath 2001; Bellwood and Hughes 2001; Beger et al. 2003), remote sensing data have not been used and spatial information on reefs was consequently poorly estimated (e.g., surface area is crudely estimated by Bellwood and Hughes (2001)). These coral reef studies considered a limited number of positional (e.g., latitude, longitude, distance to center of diversity) or environmental predictors (e.g., surface areas, turbidity) while there is evidence that other local factors quantifi- able from remote sensing images, such as presence of particular geomorphologic zones (e.g., pinnacles in lagoon), are also of importance (Adjeroud et al. 2000a). Indeed, if very general rules can be highlighted when considering very large geographic gradients (Bellwood and Hughes 2001), the effects of positional or environ- mental factors on biodiversity cannot be neglected for Fig. 1 Location of Kuna Yala archipelago (source: http:// regional or archipelago-scale analysis (Gaston 2000; www.reefbase.org) and its three Corregimientos or political units (Nargana, Tubuala, and Ailigandi). The bottom panel highlights Cornell and Karlson 2000; Adjeroud et al. 2000a, Fab- the current Caribbean Panama coral reef layer in ReefBase, also ricius and De’ath 2001). Our Kuna Yala data set com- used in Spalding et al. (2001) for mapping and inventory of Kuna bining detailed coral reef geomorphology maps and Yala reefs. Three discrete reef regions appear. Compare this map benthic diversity censuses also enables us to explore if with Figs. 2 and 3 remote sensing maps can be used to predict coral diversity within a 480-km-long Caribbean reef track. cover and compared with historical records. The data set describing the present situation was acquired mostly in May–June 2001 during a 6-weeks cruise spanning the Material and methods entire archipelago from Punta Anachukuna to Punta Porvenir. Live cover and diversity of hard corals, soft Nearly 600 field observations were collected by snor- corals, and sponges were assessed. Since the survey keling in 2 weeks in May–June 2001 during a cruise on 33 the R/V Urraca (Smithsonian Tropical Research Insti- ment, (3) each classification is processed to remove noise tute). These observations were made at various scales: and correct misclassification by using morphological geomorphology, habitat, community, and dominant operators (e.g., to refine a contour) or a posteriori species using a rapid assessment protocol (i.e., semi- manual contextual editing (to reassign a group of mis- quantitative description of benthic cover for habitat and classified pixels to a more adequate category). community levels, and qualitative description for geo- This protocol, and the techniques we have developed, morphological and dominant species levels). For map- is very different than the typical habitat mapping exer- ping purposes, we were constrained by the 30 m spatial cise that can be found explained in the literature or resolution and limited spectral resolution (only the first handbooks (e.g., Green et al. 2000). Indeed, the con- three spectral bands are informative on underwater straints are different. Large spatial extent, variations in targets) of Landsat data. Therefore, a site consists of an habitat types, and limited ground-truth data prevent area covering two to three Landsat pixels (1 pix- using habitat mapping methods in an operational and el=900 m2), except in transitions. We conducted large- accurate way. A recent study conducted in the southern scale ‘‘transects’’ of several hundreds of meters or a few Great Barrier Reef provides a clear demonstration that kilometers, in order to cross different sites of interest regional habitat mapping can produce results of pre-selected on the images and georeferenced. Pre- doubtful value, with map overall accuracy ranging from selection intended to capture the highest diversity of sites 12 to 70% for reefs only few kilometers apart (Joyce in terms of color (due to bottom types and depth vari- et al. 2004). Another recent study confirmed on ten ations) and spatial structure. Spatial structure criteria different sites worldwide that typical habitat mapping include texture (related to two-dimensional patchiness of techniques seldom yield 90% accuracy, using Landsat 7 habitats), transition (mono-dimensional variation in but also higher spatial resolution sensors such as IKO- color along sharp or large geomorphological gradients), NOS (Andre´foue¨ t et al.