Species on the move make way for new feeding interactions

Marine species are on the move due to global change, but can they start feeding on local species that they have never encountered before?

Photo: Audun Rikardsen

Written by Laurene Pecuchet and Marie-Anne Blanchet

Temperature changes in the world’s ocean are causing marine species to move. As these species settle in new areas, they might come across species they never encountered before. In order to establish themselves in a new area they need to feed on the unfamiliar species. Can the newcomers feed on these, and what could be the consequences for the local ecosystems? In a new study published in Global Change Biology, researchers from the BRIDGE research group at Norges fiskerihøgskole (NFH) predicted feeding interactions between range-shifting species and Arctic species and investigated the potential impacts of these new interactions on the Barents Sea Arctic ecosystem.

Many boreal species (orange) are expanding their distribution range polewards, entering the historically Arctic ecosystem (blue)

The Barents Sea is a productive ecosystem located off the northern coast of Norway and Russia. This ecosystem has experienced large species redistribution during the last decades with poleward shifts of boreal species.In recent years (2014-2017) about 10 boreal species were found inside the nets of scientific surveys in the Arctic region of the Barents Sea. These boreal species have the common characteristic of being generalist species, meaning that they eat a large array of preys. Then, could these incoming boreal species start feeding on Arctic residents, and by doing so deepen their impact on the Arctic ecosystem?

To predict feeding interactions between the incoming boreal species and the Arctic residents, the BRIDGE researchers used previous knowledge on who eats whom between the species in the Barents Sea.

–We found that all incoming boreal species have the same potential to feed on Arctic preys, as well as being eaten by Arctic predators, says the researchers. – Cod, for example, is predicted to start feeding on Arctic species such as polar cod or the northern krill, but they could also become the prey of Arctic mammals such as the narwhal or the beluga.

Range-shifting boreal species (orange) such a cod might start to eat and be eaten by Arctic species (blue)

These new feeding interactions might intensify the impacts of invasive boreal species on the Arctic ecosystem by reshaping the network of who eats whom. Because the incoming species are generalists, they have the potential to connect some food chains more tightly together. This could make the system less resilient to perturbations because they could propagate through the network more easily.

In a rapidly changing world, it is becoming harder and harder to keep up with the pace of new ecological interactions. To document these changes analysis such as stomach content and isotope analysis can be too time and effort consuming. In this study, the authors circumvent these problems by using machine learning and prior knowledge on who eats whom to infer ecological interactions and help predict the impacts of range‐shifting species on ecosystems.

The article “Novel feeding interactions amplify the impact of species redistribution on an Arctic food web”

The research group BRIDGE

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