Open-source geo-spatial software initiative helps to produce global map of coral exposure to stress
Marine researchers from the Wildlife Conservation Society (WCS) and spatial ecologists from the Faculty of Geo-Information Science and Earth Observation (ITC) have created a map of the world’s corals and their exposure to stress factors, including high temperatures, ultra-violet radiation, weather systems, sedimentation, as well as stress-reducing factors such as temperature variability and tidal dynamics. The study, say the authors, will help to conserve some of the world’s most important coral reefs by identifying reef systems where biodiversity is high and stress is low, as well as ecosystems where management have the best chance of success. Supercomputing facilities at ITC and open-source geo-spatial software were used to generate global maps based on satellite observations and oceanographic model outputs to derive variables that reinforce and reduce stress in corals.
After the paper appeared online in journal PLoS One it was quickly picked up by a variety of scientific magazines including Nature. The authors include: Joseph M. Maina of WCS and a doctoral student at Macquarie University, Sydney, Australia; Timothy R. McClanahan of WCS; Valentijn Venus of Faculty of Geo-Information Science and Earth Observation of the University of Twente (ITC); Mebrahtu Ateweberhan of the University of Warwick; and Joshua Madin of Macquarie University.
“Coral reefs around the globe are under pressure from a variety of factors such as higher temperatures, sedimentation, and human-related activities such as fishing and coastal development,” said Joseph M. Maina, WCS conservationist and lead author on the study. “The key to effectively identifying where conservation efforts are most likely to succeed is finding reefs where high biodiversity and low stress intersect.” Using a wide array of publicly available data sets from satellites and a branch of mathematics known as fuzzy logic, which can handle incomplete data on coral physiology and coral-environment interactions, the researchers grouped the world’s tropical coral reef systems into clusters based on the sum of their stress exposure grades and the factors that reinforce and reduce these stresses.
The first cluster of coral regions—Southeast Asia, Micronesia, the Eastern Pacific, and the central Indian Ocean—is characterized by high radiation stress (sea surface temperature, ultra-violet radiation, and doldrums weather patterns with little wind) and few stress-reducing factors (temperature variability and tidal amplitude). The group also includes corals in coastal waters of the Middle East and Western Australia (both regions have high scores for reinforcing stress factors such as sedimentation and phytoplankton). The second cluster—including the Caribbean, Great Barrier Reef, Central Pacific, Polynesia, and the Western Indian Ocean—contains regions with moderate to high rates of exposure as well as high rates of reducing factors, such as tidal ranges and temperature variability.
Overall, stress factors such as surface temperature, ultra-violet radiation, and doldrums are the most significant factors, ones that ecosystem management has no control over. What is controllable is the mitigation of human impacts that reinforce radiation stress and where managers decide to locate their protected areas. “When radiation stress and intensive fishing are combined, the reefs have little chance of surviving climate change disturbances because they both work against the survival of corals that are the foundation of the coral reef ecosystem,” said Dr. Tim McClanahan, WCS Senior Conservationist and head of the society’s coral reef research and conservation program.
Reprinted by permission from Macmillan Publishers Ltd: Nature
(Nature 476, 375 (25 August 2011) doi:10.1038/476375d,
Ecology: Mapping reef stress), copyright 2011.
The study is an excellent example of how decision makers are now trying to integrate oceanographic data (analysis and model output available in formats like netCDF) with ecological data (i.e. the GPS-based observations of coral health). They usually have to find ways to convert the oceanographic data into a compatible Geographic Information System (GIS) format so they can be used in their GIS tools (e.g. ArcGIS™ by ESRI®). However, current GIS tools do not handle the time varying, multidimensional datasets well and provide little support for time or spatial animation. Hence the authors opted, amongst other tools, for the open-source Integrated Data Viewer (IDV) developed by Unidata which thanks to its multidimensional VisAD-data model facilitated seamless data integration and facilitated relating coral exposure to environmental stressors on a global scale.
The authors recommend that the study results be used to formulate management strategies that would include activities such as fishing restrictions, the management of watersheds through improved agricultural practices, and reforestation of coastal watersheds that play a role in healthy coral systems. “The study provides marine park and ecosystem managers with a plan for spatially managing the effectiveness of conservation and sustainability,” said Dr. Caleb McClennen, Director of the Wildlife Conservation Society’s Marine Program. “The information will help formulate more effective strategies to protect corals from climate change and lead to improved management of reef systems globally.”
Department of Natural Resources (NRS), Faculty ITC, University of Twente, The Macquarie University’s Higher Degree Research (HDR), and the Wildlife Conservation Society Marine Program contributed to the mapping project, with support from the John D. and Catherine T. MacArthur Foundation.