The Use of Population Connectivity in the Design of Networks of Marine Protected Areas

Abstract

Ecological connectivity, the exchange of individuals among spatially fragmented habitats, is an important criterion in the design of networks of marine protected areas (MPAs). However, there are gaps in taxonomic and geographic application of knowledge on connectivity patterns to conservation planning. The main objectives of this thesis are to 1) quantify how connectivity has been applied to the design of MPAs and 2) apply lessons learned to the Atlantic coast of Nova Scotia by comparing different methods for estimating and prioritizing connectivity for management. 11% of 746 MPAs from six regions with advanced systematic conservation planning considered connectivity as an ecological criterion in their design. Practical considerations for improving implementation include considering whether to prioritize connectivity, identifying the role of a MPA in supporting connectivity, identifying the appropriate temporal and spatial scale, and improving regional patterns of connectivity. Dispersal for species with a short propagule duration could be adequately estimated with average current velocity. At the spatial scale of management units (10s of km), binning current speed by direction produced dispersal area estimates comparable to those from a biophysical model, therefore providing a lower cost and resource intensive tool. In-silico habitat fragmentation of kelp reinforced that most kelp patches are sustained by self-recruitment. Negative impacts of habitat fragmentation were no greater than the impacts of habitat loss alone, except when a critical threshold of habitat loss was surpassed (70-80 %). Priority areas for protection of kelp, that also minimized connectivity of an invasive biological threat, tended to be large, upstream patches. The priority of kelp patches also varied when testing different connectivity objectives, supporting that the role of an area in supporting connectivity is an important consideration. These results indicate that connectivity should always be considered in the design of MPAs, but the way in which information on dispersal patterns is incorporated will depend on the species of interest, investment of time and resources, and having a diverse toolkit. This thesis provides new insights into how and when to prioritize connectivity in the design of MPAs with the goal to help future proof MPAs through connectivity pathways and hubs.