Reducing Nutrient Loading from Agriculture to Lake Ecosystems – Contributions of Resilience Principles

Nutrient loading from agriculture is a critical threat to aquatic ecosystems, affecting their ability to provide safe drinking water, and limiting the provision of ecosystem services such as water-based recreation. Efforts to manage the problem typically focus on encouraging, incentivising, or requiring use of best management practices to reduce nutrient inputs on farms and limit their transport to water systems. For example, protecting and restoring wetlands and riparian ecosystems, which filter nutrients from run off and offer co-benefits such as carbon sequestration, terrestrial and in-stream habitat, and recreational opportunities, are important strategies. However, in many agricultural catchments, nutrient concentrations in waterbodies remain high despite such interventions. Reasons for this are myriad and include low uptake of best management practices on farms, timelags in ecosystem response, legacy phosphorus stored in soil and lake sediments, and changing weather patterns associated with climate change. This chapter explores the potential contributions of resilience thinking to reducing nutrient loading to waterbodies and minimising its impacts by treating agricultural watersheds as social-ecological systems, recognising the pressures on freshwater ecosystems caused by human activities throughout the watershed as well as the reliance of such activities on functioning aquatic ecosystems and the services they provide. This involves more explicitly accounting for interactions within agricultural social-ecological systems, planning at the catchment scale, adaptive management, and new governance arrangements. We draw on some lessons learned from a range of innovations developed for technical management practices, policy and governance approaches. We translate these lessons into pathways for reduced nutrient loading for sustainable management of lakes in the face of changing climate, degrading aquatic ecosystems and increasing demand for land and food.