An estimated 5 million tonnes of plastic enters SE Asian waters each year, with much of this ending up in the coastal environment. The Philippines, with a population of 110 million, relies strongly on coastal tourism for its economy, and Philippine marine plastic pollution has been attributed to the reliance on single-use plastic (SUP) for everyday household essentials. Although research to date has focused on identifying the quantity and location of plastics, such as the much publicised but potentially misleading "vast ocean garbage patches" (which are, in reality, more like plastic soups), less research has been conducted on determining transport pathways and budgets of marine plastics. In this project, we will focus on the Cebu Islands (Philippines). The challenge of reducing the impacts of marine plastics in this region is acute, and there is an urgent need for sustainable economic development. The Cebu Islands are home to the biggest marine protected area in the Philippines. Through the development of a Sources-Pathways-Receptor (SPR) modelling framework, in this project we will map the transport of marine plastic litter (MPL) from source to sink. The model will incorporate novel non-conservative terms to simulate transformation of the plastic waste as it travels through the system, incorporating, among other processes, changes due to exposure to UV light and mechanical degradation due to wave action. We will focus on the impacts of the plastic waste to mangroves - an unknown but potentially important filter in the plastic cycle. It is known that mangroves capture macroplastics (plastics larger than 5 mm) in their roots, and through the intense burrowing activities of bioturbators such as crabs can act as excellent filters and sinks for relatively large pieces of plastic. However, we will determine the role of mangroves in the microplastic (plastics less than 5 mm) cycle, since mangroves could, in fact, act to further disperse plastic as even smaller particles over longer timescales. By accurately resolving the content and type of MPL in space and time, the impact to receptors (services, industry and environment) will be accurately assessed: both physically (mortality and impact to ecosystem function) but also economically (to industries such as fisheries, aquaculture and tourism).

The economies of Southeast Asian countries (Malaysia, Indonesia, Vietnam, Thailand, the Philippines), and hence living standards of people living in this region, are intimately coupled to the ocean which is a valuable source of protein via fisheries and income via tourism. Many of these regions also contain valuable natural resources in the shape of forests and peatland which can be harvested for timber, converted to agricultural systems and which store carbon thus regulating the composition of our atmosphere and reducing the rate of global warming. Working out best how to extract resources from terrestrial systems with minimal impact on the coastal systems that they are linked to via rivers is an enormous challenge; logging and land clearance leads to soils entering rivers and coastal waters, changing their transparency, altering fisheries and ultimately losing carbon to the atmosphere. What is needed to understand the best way to manage these competing pressures on the natural environment is information about how it functions and about how the communities which use these systems will respond to likely changes. Putting together the natural scientists who think about soils, forests and rivers with those social scientists who understand what drives people to make the decisions about how they live their lives that they make is a massive challenge. However unless we do this we will only understand one half of the problem. In this project we will therefore both sample coastal waters and rivers in western Borneo to assess their functioning and health and assess the needs of the local communities via questionnaires and interviews. We will put these two halves of the project together via a series of workshops which we believe will better help Malaysia cope with environmental change and manage their natural resources in a sustainable manner. Key elements of the project involve sampling a range of disturbed and Undisturbed rivers and coastal waters, working out the key processes which lead to the loss of soil into the Marine environment, what happens to it and how it affects the ecosystem and looking at how these processes have changed over time and how people's exploitation of coastal espouses have evolved in parallel.