Elevated seasonal temperatures eliminate thermal barriers of reproduction of a dominant invasive species: A community state change for northern communities?

Abstract Aim Couple field and modelling studies to evaluate the effects of rising water temperature on reproduction of a dominant marine species and how temperature induced changes in a species' phenology may affect fouling communities that occur along a temperature gradient. Location North western Atlantic. Methods We examined the interaction between maximum and seasonal elevations in seawater temperature and reproductive phenology of a global invader to forecast the effect of climate warming on traits associated with the spread and establishment (i.e., growth and reproduction) of an invasive species. We then coupled these data with a study of early succession along a temperature gradient to forecast invasion success in species assemblages across a range of latitudes. Results Elevated seasonal temperature will lead to greater asexual reproduction and to multi‐annual sexual reproduction in areas that currently have bi‐annual or annual reproduction. The output from our model combined with our field studies of early succession in communities suggest that in colder environments, communities may be more affected by climate‐induced shifts in reproductive phenology as they have more free space at the beginning of the growing season and fewer competitively superior species. Main conclusions Predicted elevated water temperature will eliminate the thermal barriers that limit reproductive success of a cosmopolitan invasive species. Increased reproduction combined with limited biological resistance in regions with cooler water temperatures may lead to a community state change.