The impact of ocean plastic on the dynamics and management of marine populations

Abstract

We explore the impact of ocean plastic on population dynamics, specifically predator- prey interactions. We develop two approaches. In the first we use optimal control tools to understand how damaging plastic can be. In this worst case approach we find plastic time series which are most damaging to the predator-prey dynamics. How damaging is captured through cost functions. We may seek to mimimise population abundance at a given final time or minimise time taken to reach a given abundance. We develop algorithms which determine these most damaging time series. In the second part, we develop a stochastic, steepest descent, home range model to explore how plastic impact on migration paths of prey species. We then add predators to this home range model. We explore how various factors such as extent of plastic, predation rate, reproduction rates and maximum migration times influence the patterns of migration and prey time series.