Climate Change and Marine Reserves: What Do We Know, and How Much Do We Need To Know?

Climate change will affect how species use space across a range of spatial scales.  At large scales, some species have already experienced changes in distribution related to climate effects, and others are predicted to do so.  At medium scales, changes in activity may influence rates of dispersal.  At small scales, little work has addressed how changing climate may influence the home range (HR) of an individual, which is an important component in the design of marine protected areas (MPAs).  Some species show changes in HR or activity levels among seasons, which may aid in the prediction of responses to climate change, as could an understanding of bioenergetics and food requirements.

We constructed an MPA-population model parameterized with data for lingcod to determine how the amount of information on space use affected predictions of the efficacy of MPAs.  Specifically we compared the use of mean HR size (less information) to utilization distributions (UD, more information)—both derived from acoustic tracking.  The key difference between the two is that an individual has an equal probability of being in any part of its mean HR, while in UD some areas are more heavily used than others.

Biomass was 10% higher and numbers 5% higher when we used the UD to describe space use by lingcod than when we used mean HR.  Thus while there is a difference between the two measures of space use, the simpler measure was conservative and may be the better metric for the design of MPAs in an uncertain future.