A Predatory Wall against climate induced population expansion

Climate is rapidly changing, with rising temperatures affecting various aspects of our environment. As our planet undergoes warming, numerous species are expected to expand their ranges in search of suitable habitats. In our recent study published in Ecology (Durant et al. 2023) we highlight the intricate relationship between climate warming, trophic interactions, and population expansion.

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Effect of the cod (in blue) distribution on haddock (in black) geographical expansion. The blue shaded area corresponds to the average distribution of haddock (see details in Durant et al. 2023). The red lines indicate the limits of haddock distribution and is interpreted as a “predatory wall” from the cod preventing the haddock expansion.

Climate warming is altering ecosystems worldwide. As temperatures rise, many species are compelled to shift their geographic ranges in search of new suitable habitats leading to population expansions.

For our study, we focused on an often-overlooked aspect of population expansion: the influence of trophic interactions (e.g., the effect of the presence of predators). While climate warming may create opportunities for species to expand into new areas, the presence of predators can act as a barrier, inhibiting population expansion.

We investigated the impact of predatory interactions on population expansion using two iconic fish species that are the Atlantic cod Gadus morhua as predator and the haddock Melanogrammus æglefinus as the expending population prey. From a previous study, we already knew that cod could negatively affect haddock in the Barents Sea (Durant et al. 2020, post).

Here, our study on two different ecosystems (North Sea and Barents Sea) demonstrated that predatory interactions could significantly hinder population expansion under climate warming conditions. Predators may exploit newly colonized areas or prey upon dispersing individuals, preventing them from establishing viable populations, which highlights the importance of understanding the complex ecological interactions that shape population dynamics. The presence of predators can create a "predatory wall," limiting the ability of prey species to establish themselves in newly available habitats.

Our study highlights the intricate relationship between climate warming, predatory interactions, and population expansion. By demonstrating the detrimental impact of predatory walls on species' ability to thrive in newly colonized areas, the research underscores the importance of considering ecological interactions in conservation strategies.

Our research emphasizes the need for a holistic approach to ecosystem management. Simply preserving suitable habitats for species is not enough; understanding the broader ecological context, for instance by including predator-prey dynamics, is crucial for effective conservation.

References:

Durant J.M., Holt R.E., Ono K., Langangen Ø. 2023. Predatory Walls May Impair Climate Warming-Associated Population Expansion. Ecology e4130, doi:10.1002/ecy.4130.

Durant J.M., Ono K., Stenseth N.C., Langangen Ø. 2020. Non-linearity in interspecific interactions in response to climate change: cod and haddock as an example. Global Change Biology, doi:10.1111/gcb.15264.