Cumulative impact management is the process of determining the desired future state of an ecosystem, and how this will be achieved through control of developments that may have direct, indirect or interactive impacts on that ecosystem (Cuddington et al. 2013). Impacts may interact in additive, synergistic or antagonistic ways, and understanding the nature of potential interactions is crucial in determining optimal management strategies (Anthony et al. 2013). An example of cumulative impacts management is the situation where multiple threats to seagrass in the Great Barrier Reef were assessed in a spatial framework, to determine hotspots of anthropogenic risk (Grech et al. 2011).
At the national level and within most states, the landscape for cumulative impact management is poor in terms of articulation and development of legislation, policies and plans. Cumulative impacts are acknowledged in management plans, but pressures are still treated individually with little effort to develop frameworks for analysing or managing interacting pressures within or among industries. Efforts have been further developed through the development of a framework for understanding cumulative impacts to inform decision-making in the Great Barrier Reef World Heritage Area (Anthony et al. 2013). The EPBC Act also allows for strategic assessments that consider large-scale cumulative impacts in coastal regions.
At lower levels of management, the treatment of cumulative impacts is less well developed. In many states, few agencies are working to assess and manage cumulative impacts, or to assist local governments in this regard. Cumulative impacts are largely ignored by legislation for development and planning, and are rarely assessed when new developments take place. Insufficient funding, expertise and community support is limiting the progress of local councils towards implementing adaptive planning strategies (Gurran et al. 2013).
Current cumulative impact management frameworks are often provided as guides, and therefore lack structure, incentives and resources for appropriate long-term management. Ideally, under a framework of cumulative impact management, a proposed development would be considered in the context of previous impacts, other potential developments in the broad surrounds and broadscale impacts of the activity itself. In theory, this could be achieved through models of environmental impacts of multiple pressures.
Greater understanding of cumulative impacts is required from management agencies, including understanding of the practical limitations of cumulative impact management at local and regional scales. Local and regional bodies are increasingly having to deal with cumulative impacts and pressures that are larger in scope than the areas for which they are responsible. Typically, management remains local in scale, and there are few examples of management at larger scales. When allocated limited resources, management should identify sites where achievable reductions of local pressure will achieve the greatest results in the context of global pressures (Brown et al. 2014).
Challenges are not only administrative, but also scientific. The impact of multiple interacting pressures is an inherently difficult field of research, and recent studies have led to only incremental understanding of cumulative impacts on ecosystems or species. Obtaining controlled field samples to quantify cumulative impacts is difficult, particularly because cumulative impacts are often highly variable through space and time, and require extensive data to attribute impacts to different pressures.
The outlook for cumulative impact management in the short and long terms is poor, unless all levels of government adopt effective frameworks backed by strong incentives and regulations. Effective cumulative impacts management requires the development of approaches to facilitate realistic and respectful interactions between managers, researchers, government advisers, stakeholders and communities.