Predicting climate-induced changes in population dynamics of invasive species in a marine epibenthic community

As climate change and invasive species, both individually and in concert, continue to elicit responses in native communities, we are challenged with finding strategies for predicting the strength of such impacts. The effects of invasive species are often determined by their abundance, and warming temperatures can alter species' demographic rates and, thus, population growth rates. Here, we combined lab experiments, field experiments and observations, and population modeling to predict the population dynamics of three marine invaders in response to climate warming. We projected population growth rate at an ambient and an increased temperature predicted by climate-change scenarios (+ 4 °C) for three invasive species in the epibenthic fouling community of Bodega Harbor, California, USA: the tunicates Botrylloides violaceus and Botryllus schlosseri and the bryozoan Watersipora subtorquata. There was a positive effect of temperature on population growth rate for B. schlosseri, and further analysis revealed that this predicted increase was driven by warming effects on settler growth rate and adult fecundity. Increases indicated for non-native marine fouling species are especially pertinent when considering the potential cascading effects on community composition and functioning that can result from species invasions. Our results highlight the potential for marked increases in an invasive species in response to climate change, as well as the promising role that population modeling can play in elucidating the mechanisms of such responses.

► Population demographic modeling can be used to predict responses to climate change.
► We predicted impacts of ocean warming on three invasive marine species.
► Models were parameterized using lab and field experiments and observations.
► Warming is predicted to increase population growth rate for one invasive species.
► Increased population growth was driven by changes in fecundity and growth rates.