What secrets do squid beaks hold?

MARE researchers José Xavier, Filipe Ceia and José Queirós are co-authors of the study “Insights on long-term ecosystem changes from stable isotopes in historical squid beaks”, recently published in the scientific journal BMC Ecology and Evolution from the Springer Nature group.

Assessing the historical dynamics of the main elements of the trophic web is fundamental to understanding the impact of climate change on the structure of Arctic marine ecosystems. In this context, a team of researchers, led by Alexey Golikov from the GEOMAR Helmholtz Centre for Ocean Research Kiel, used two species of squid abundant in the Arctic (Gonatus fabrici and Todarodes sagittatus) to assess this impact.

“Knowing that the Arctic region is being impacted by climate change, this study shows how Arctic marine animals (in this case squid) can detect long-term climate change, from 1844 to 2023,” explains MARE researcher José Xavier. To do this, the researchers analyzed changes in the development of squid (ontogenetic changes), through the signatures of stable isotopes in the hard chitin structures (beak) of these animals.

This analysis found changes in the squid's diet and habitat use. These results are consistent with the phenomenon of Atlantification, i.e. the arrival in the Arctic of warmer and saltier waters from the Atlantic. “Over the course of the century, changes in the trophic ecology of squid have coincided with the Atlantification (or borealization) of Arctic ecosystems. This means an influx of boreal species from the North Atlantic into the Arctic domain due to climate change. This transformation resulted in a greater generalization of food webs, leading to profound changes in this ecosystem. This study was able to detect these changes in squid species,” explains Filipe Ceia.

These results suggest that abundant opportunistic mesopredators with short life cycles (such as squid) are good candidates for retrospective ecology studies in marine ecosystems and for identifying changes in ecosystems caused by climate change. Furthermore, it is possible to conclude that the greater generalization of Arctic food webs is reflected in the increased diet generalism and niche width of squid, while the greater abundance of boreal piscivorous fish is reflected in the increased trophic position of squid.

According to José Xavier, “This study also shows that squid may be one of the groups of marine animals best able to adapt to climate change in the future.”