WIO-Ridge to Reef: An Ecosystem Based Approach to Biodiversity Conservation in the Western Indian Ocean

Abstract
The continuing degradation of coastal-marine ecosystems has serious consequences on the livelihoods of millions of people who currently depend on them. While climate change is considered the most serious risk to the blue carbon ecosystems, land-sourced pollutions are increasingly becoming a key threat in many regions of the tropical world. This project, termed WIO-Ridge to Reef (WIO-R2R), aims to address the problem of land-sourced pollution on near coastal ecosystems (coral reefs, seagrass, and mangroves, also called the blue carbon ecosystems) using an adaptive management based framework commonly referred to as Ridge to Reef (R2R). The R2R land-sea management framework will focus on reducing land-source pollution and maintaining a sustainable regime of sediment and nutrients discharge. We will achieve this by equipping stakeholders with necessary tools for developing integrated solutions for alleviating pressures on blue carbon ecosystems, and threats to livelihoods that emanate from land-use change in two of East Africa’s largest agricultural expansion corridors, Kenya’s Tana Basin and Tanzania’s Rufiji basin. WIO-R2R will focus on building knowledge and understanding of resource and ecosystem dynamics, and feed this knowledge into adaptive management practices, supporting the development of flexible institutions and multilevel governance systems, and enhancing the capacity of coastal managers to deal with external perturbations and change in the catchments and coastal ecosystems. We will achieve these broad goals using four objectives. Firstly, we will generate knowledge on sediment transfer from catchments to adjacent near-shore areas. We will develop catchment models to simulate historical sedimentation, and derive sedimentation proxies from sediment cores from Lamu and Ungwana Bay reef systems, which are adjacent Tana basin in Kenya and from the southern Rufiji Delta and on Mafia Island in Tanzania. We will apply scenario based catchment modelling to (a) determine the critical source areas (areas contributing most of the pollutants in a watershed) and the amount of river-borne sediment and nutrients reaching coral reefs under different land-use and climate scenarios; and (b) spatially test the effectiveness of spatially explicit land-use management actions at reducing pollution. Secondly, we will generate knowledge on impact pathways of sediment and nutrient pollution on coral reefs. We will investigate the sediment trail on near-shore marine areas using Earth Observation and field methods, and evaluate the impacts of sediment and nutrient exposure on coral and seagrass cover, fish biomass and on mangroves. Thirdly, we will assess the extent to which current catchment and coastal management regimes are able to transfer knowledge generated under objectives 1 and 2 to develop adaptive capacity. We will assess adaptive capacity of catchment governance regime, and use these to identify important shortfalls and potentials for adaptive capacity enhancement. Finally, we will assess trade-offs between agriculture, grazing, fisheries, conservation, and livelihoods, for prioritization of management actions using knowledge generated from the three objectives and the systematic conservation-planning approaches to identify the most cost-effective management actions and priority areas for management intervention to maximize threat reduction to key coastal biodiversity and the associated livelihoods.

WIO-R2R is a project set up to inform land sea management framework in seven basins in 5 countries in the Western Indian Ocean region, including Kenya, Tanzania, Mozambique, Madagascar, and Mauritius.

ongoing study, findings in Madagascar suggest future land use is more important than climate change in mediating sediment pollution. More information can be found here: https://www.goto.mq.edu.au/9a