This study proposes to examine the spatial and temporal environmental changes affecting coral reef ecosystems in the Western Indian Ocean. In this multi-disciplinary project, environmental geochemists dealing with the direct data acquisition on biological archives (corals), will work in partnership with climate scientists, environmental modellers and ecologists. This will allow direct comparison of the geochemical data obtained by the geochemist with models of river discharge and pollution and ecological changes. Integration of these data should provide a far better understanding of the entire ecosystem in the region investigated and lead to improved sustainable management of the coastal environment. The project is therefore divided into two interdependent sub-projects: 1) a coral proxy-climate-based, and 2) a model-ecology-based project. As part of sub-project 1, we will drill coral cores to reconstruct environmental changes in various reef complexes across the tropical Indian Ocean (Mauritius, Madagascar, Tanzania, Kenya) in relation to natural climate change and anthropogenic influences. To meet this goal we will examine several biological (growth rate, density, calcification) and environmental parameters (luminescence, trace elements, nutrients, isotopes) in massive coral skeletons of the species Porites sp. and Diploastrea sp. which continuously grow for up to 400 years. As a primary objective, we will determine the seasonal variability in river runoff (soil erosion), sea surface temperature (SST) and coral growth due to climatic baselevel changes, foremost of decadal-scale variability and intermittent extreme events along the path of cyclones. This climatic baseline includes hydrological reorganisations during e.g. the Medieval Warm Period around 1200 AD, the Little Ice Age around 1700 AD, and the Mid-Holocene. As a secondary objective, we will assess anthropogenic impacts on river runoff and resultant thermal and growth anomalies in Indian Ocean catchments as offsets from the climatic baseline levels in hotspots of land degradation. The major objective of sub-project 2 will be the quantification of land use and hydrological change in tropical catchments over decadal to century scales, and to determine the relative importance of anthropogenic versus climate forcing. For the catchments selected in correspondence with subproject 1, and adjacent to the reefs studied, databases of land use change, annual (and seasonal) river discharge and sediment load patterns, and the extent of the freshwater plume onto the shelf will be modelled. Temporal resolution will be matched to the resolution of the coral growth banding carried out in sub-project 1 which is monthly to annual. Geochemical characterization of recent and historic sediments will be performed from the rivers and nearshore coastal waters near to the studied coral reefs (cf Kamp-Nielsen et al., 2002). Hence this subproject aims to determine the spatial and temporal variations of four unknowns: (1) land use change, (2) river discharge patterns, (3) coastal sediments, and (4) extent of the freshwater plumes. These data will provide the link between land use changes, river runoff, sediment compositions and the coral proxy records that are required to distinguish the relative roles of natural and anthropogenic induced changes in the coral reefs. Finally, we will link the results of subproject 1 and 2 to long-term ecological reef monitoring programmes of our partner institutions to infer the impact on temporal and spatial biodiversity changes in coral reef ecosystems across the western Indian Ocean. The results of this project will provide a broader management context and to allow conservation scientists to identify environments where corals are expected to survive climate change and insure that management and conservation actions are focused on these key areas. Principal Investigator: Dr. Jens Zinke Royal Netherlands Institute for Sea Research Marine Geology Department P.O.Box 59 AB1790 Den Burg, Texel The Netherlands jens.zinke@nioz.nl jens.zinke@falw.vu.nl Tel: +31207701863 Co-Principal Investigator: Prof. C. Reason University of Cape Town Dept. of Oceanography E65 Rondebosch 7701 Cape Town, South Africa Tel. +27(0)21 6504117 Chris.Reason@uct.ac.za National Coordinators: Western Indian Ocean investigators: Matthieu Rouault, University Cape Town (Climate diagnostics Indian Ocean) Tim McClanahan, WCS Kenya (Coral Reef ecology and coral pollution indicators Kenya) Josef Maina, Kenya (GIS, Runoff modelling East Africa, WIO islands) Christopher Muhando, Ophery Ilomo, IMS Zanzibar (Coral Reef ecology and coral pollution indicators Tanzania) Bemahafaly Randriamanantsoa, WCS Madagascar (Coral and Sediment analysis, monitoring Madagascar) Monica Tombolahy, Conservation International (Coral Reef seawater monitoring Northern Madagascar) Steve Mwangi, KMFRI Kenya (Seawater quality measurements) Manvendra Singh, MOI Mauritius (Coral biology Mauritius) Shoals Rodrigues (Coral Reef Ecology and Monitoring Rodrigues) International investigators: Prof. Malcolm McCulloch, UWA Perth, Australia (Laser-Ablation trace metal analysis, U/Th dating fossil corals) Dr. Miriam Pfeiffer, RWTH Aachen, Germany (Climate analysis coral cores Tanzania, Kenya) Dr. Lars Reuning, RWTH Aachen, Germany (Carbonate diagenesis) Dr. Gert-Jan Brummer, C. Grove, Royal NIOZ, The Netherlands (Coral luminescence and geochemistry) Dr. Jan Vermaat, Prof. J. Aerts, VU Universiteit Amsterdam , NL (Environmental Modelling Coordinator)