Generalists and competition may be important in limiting range
expansion, evidence from the frontlines of climate change
Abstract
Climate-driven range expansions of individual species are
well-documented; however, corresponding community shifts are not. This
lack of widespread community change may indicate communities can resist
wholesale change with the arrival of new species. In the northern Gulf
of Mexico, climate change is driving the expansion of black mangroves
(Avicennia germinans) into areas traditionally dominated by smooth
cordgrass (Spartina alterniflora). This study investigates the effects
of these changes on the species composition of animals and habitat
structure in Louisiana, U.S. with implications for how species expand
their range under shifting climactic regimes. Using quantitative nekton
sampling and satellite imagery analysis over two decades, we observed a
substantial increase in winter temperatures of 3.5°C and a significant
regime shift from marsh to mangrove habitats. Despite these remarkable
physical and habitat changes, the species composition remained stable,
suggesting that local species interactions may mitigate the effects of
climate-driven range expansions. Our findings highlight the resilience
of estuarine communities to rapid environmental changes and emphasize
the need for further research on the indirect effects of habitat shifts
on food web dynamics.