The giant warty squid (Moroteuthopsis longimana), a deep-sea species from the Scotia Sea in the Southern Ocean, might be a key to assay to track one of the planet’s most concerning pollutants: mercury. Mercury is a toxic element that bioaccumulates in marine food webs, reaching higher concentrations in predators and posing risks to both wildlife and human health.
Because squids are almost impossible to study alive, scientists have to rely on their beaks, hard structures that resist digestion and accumulate in the stomachs of predators to analyse their chemical signatures. In this study, researchers analysed squid beaks collected from the 1970s to the present day to measure mercury concentrations.
The results were remarkable, despite high mercury levels in the first two decades, concentration have been steadily decreasing over the past three decades. This trend suggests that global efforts to reduce mercury emissions, such as the International Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (1972)and improvements in industrial practices, are having measurable positive effects, even in remote ecosystems like the Southern Ocean (Figure 1).
Cephalopods like M. longimana can be valuable bioindicators as they occupy a central position in marine food webs, linking smaller prey such as crustaceans and fish to large predators like seals and whales. Moreover, their short lifespan and rapid make them excellent “record keepers” of environmental conditions giving researchers a unique window into pollutant trends.
By turning squid beaks into environmental archives, scientists have provided evidence that pollution can decline when collective action is taken. These results bring hope, but also serve as a reminder of the need to sustain global commitments to pollution reduction to safeguard ecosystems.
Source: Sara Lopes-Santos, José C. Xavier, José Abreu, José Seco, João P. Coelho, Eduarda Pereira, Richard A. Phillips, José P. Queirós, Decreasing mercury concentrations in beaks of the giant warty squid Moroteuthopsis longimana in the Scotia Sea (Southern Ocean) since the 1970s, Marine Pollution Bulletin, Volume 221, 2025, 118578, ISSN 0025-326X
Author: Lucas
