ORAL - Rozo Garzón (given by Vides)

Colombia is recognized as a mega diverse country on the basis of the number of terrestrial animal and plant species occurring within its boundaries (Williams 1997). However, its privileged coasts position on both Caribbean Sea and Pacific Ocean exhibiting distinct geological, oceanographic, and climatic features could perhaps rank the country within the highest marine biological diversity in South America and among the most biodiverse in the world.

An inventory of the full variety of physical bottom types or seascapes map of Colombian territorial waters was produced as a response to provide basis to assess how marine protected areas may well capture marine habitats and thus biodiversity. This map is part of a National initiative to generate an official 1:500.000 scale map where terrestrial, marine and coastal natural ecosystems are all shown. It was made using existing data which are recognized as varying in quality and spatial coverage and have problems with compatibility between data sets.

Mapping approach is based on a benthic marine classification system conditions using enduring physiographic and recurrent oceanographic features that are known to affect distribution of communities and their component organisms. Seascapes classification system and the methods used were reviewed at expert workshops.

Seascape modeling bases on a digital depth model using ground true points obtained from various time and scale bathymetric charts. Data for the benthic realms are assembled and classified in an ecologically meaningful way and then combined (overlaid) to derive bottom seascapes maps. Each benthic seascape is uniquely defined by the combination of bottom geomorphology, sediment types and oceanic climate values or ranges.

Throughout expert knowledge undersea features were identified using slope maps, isoclines and 3D visual analysis. Sediment types were obtained from the digitalization and generalization of sedimentary facies charts. Ocean climate was classified using physical and chemical oceanographic records from the World Ocean Atlas 2001. Coastal line, mangrove and coastal lagoons extent was obtained by visual interpretation, region segmentation and unsupervised classification using 3, 4, and 5 bands of Landsat 7 ETM+ dataset. Available ecosystem level information on reef areas and sea grasses was generalized and superimposed to the generated seascapes.

A newly set for discussion regionalization of Colombian underwater territory, ranges from Realms, Provinces, Ecozones to Ecorregions and encompass a total of 155 seascapes extending 532.200 km2 of the Caribbean Sea and 360.510 km2 of the Pacific Ocean. Seascapes distribute up to a maximum of 4990 meters depth. Distinctive features of the Caribbean include the Colombia Basin covering 210.000 km2 Magdalena Fan covering an area of about 24.400 km2 in close relation to the river delta. Extensive coral reefs top the mountainous seascapes of the Tayrona Ridge Ecozone NE of the Mesoamerican platform. Malpelo Ridge and Pacific Rise are distinctive features over the Pacific Basin. The Colombia trench, running parallel along the coast is a characteristically very deep and asymmetrical depression of the Pacific sea floor. Upcoming work is pointing to seascape accuracy evaluation and verification.

This map serves as a basis for future management proposals, conservation plans and sustainable management planning.

Key words: Marine ecosystems, bottom seascapes, mapping, Colombia.

References

Williams, P. H., K. J. Gaston, and C. J. Humphries, 1997, Mapping biodiversity value worldwide: combining higher-taxon richness from different groups: Proc. R. Soc. Lond., v. 264, p. 141-148.

Instituto de Investigaciones Marinas y Costeras “José Benito Vives de Andréis”- INVEMAR,

¹ Daniel Mauricio Rozo Garzón drozo@invemar.org.co; ² Martha Patricia Vides Casado mvides@invemar.org.co; ³ Pilar Lozano Rivera plozano@invemar.org.co; ⁴Javier Reyes jreyessharp@gmail.com;

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