Quantifying and mapping marine biodiversity and ecosystem futures

One of the most pressing questions of the present day is how marine ecosystems and the essential goods and services that they provide to society will change over the coming century - and how we can adapt to and limit negative impacts while maintaining and building resilience and robustness. To answer this question, we need develop scientifically rigorous global scenarios defining plausible pathways in which the coming century may unfold in terms of human impacts on marine ecosystems. These include both broad-scale factors such as how socioeconomic developments will affect climate change and fishing effort, and finer details on interactions between human and ecological systems in the ocean. My research program will develop such scenarios, both for exploratory futures, and for 'target-seeking' futures in which a desired end-point (e.g. sustainable management of ocean ecosystems by 2050) is then worked backwards from in order to determine the policies and changes that are needed to reach that goal. To build these, we will work with stakeholders and experts to develop collaborative scenarios that span a range of plausible futures. We will then carefully quantify these scenarios to provide the inputs needed to drive an ensemble of leading marine ecosystem models to produce global-scale projections of marine ecosystems, catches, and biodiversity, and how, where, and why they will change. Using an ensemble of ecosystem models instead of a single one provides a more robust understanding of the uncertainty around marine futures, and is the default approach in the climate change sciences, yet only recently applied for ocean ecosystems. We will then complement these approaches by using a novel and dynamic ecosystem model to explore tipping-points and trophic cascades, situations in which an ecosystem shifts to an entirely different state (e.g. the cod collapse of the 1990s off eastern Canada). We will test the ability of the model to reproduce observed tipping-points under historical conditions of climate and exploitation, then run it under the global scenarios we developed to produce future simulations of ecosystem state given climate change and future fishing effort. These can then be used to produce 'risk maps' that show the likelihood of trophic cascades and the ecosystem transitioning to a new state, and help to identify policies to avoid this. Canada is a signatory to international conventions on climate change and biodiversity, and this research helps to identify how it may meet its obligations under these treaties, and helps to develop policy options for how Canada may move towards a more sustainable future for marine ecosystems over the coming century.