Conclusion and perspectives
Warming and eutrophication are expected to alter the dynamics and
simplify the structure of larger food webs (Brose et al. 2012),
facilitating species invasions and increasing their impact on invaded
systems (Sentis et al. 2021). We have shown how body size and trophic
position determine the fate of species invasions and that species
invasions can mitigate or amplify the negative effects of environmental
stressors on local communities. Our predictions showed that smaller
species are particularly likely to invade communities in warmer,
nutrient-limited environments, while communities facing cold
temperatures and nutrient enrichment are vulnerable to invasions by
larger predators. Invaders can also fill vacant niches when resident
species disappear. For example, the predicted poleward shift of smaller
zooplankton species may benefit warming Arctic habitats (Evans et al.
2020). Invading predators may also buffer local communities against
eutrophic effects at lower temperatures (as in Hughes et al. (2013)).
Therefore, invasive species may not always need to be eradicated or
controlled (Simberloff 2009; Glen et al. 2013), especially if the
associated costs are too high. On the other hand, our findings support
active management and eradication of invaders with negative impacts on
local communities, including those that destabilise local communities
such as small consumers in cold, nutrient-rich habitats (Robertson et
al. 2020). Overall, we predict that species invasions may contribute to
the downsizing of food webs (Young et al. 2016), as successful invaders
will include smaller competitors and comparatively small predators.
Acknowledgements: This research was supported by the Grant
Agency of the Czech Republic (Grant no. 21-29169S). NAP was supported by
the University of Oulu and the Academy of Finland Profi4 Grant 318930
Arctic Interactions (ArcI). AS was supported by the ANR project EcoTeBo
(ANR-19-CE02-0001-01) from the French National Research Agency (ANR).
Computational resources were supplied by the project “e-Infrastruktura
CZ” (e-INFRA CZ ID:90140) supported by the Ministry of Education, Youth
and Sports of the Czech Republic. The authors have no conflict of
interest to declare.