Antarctica's smallest marine life at risk as melting ice dilutes waters

Millions of years of evolution have left many of Antarctica’s smallest marine invertebrates with body fluids that closely mirror the chemical makeup of seawater – a finely tuned adaptation that is now under threat from a rapidly changing environment.

Melting glaciers, increased rainfall and extreme weather events are driving down salt levels in shallow coastal waters around Antarctica, a phenomenon scientists call “freshening”. And a new study warns that continued freshening could pose a significant threat to marine invertebrates in the region – one that could ultimately reshape the character of the global ocean.

The research, led by scientists at the University of Plymouth and the British Antarctic Survey (BAS), builds on earlier work by the two organisations examining how shifting ocean conditions affect some of the planet’s smallest but most ecologically important species.

Professor John Spicer, Professor of Marine Zoology at the University of Plymouth and the study’s lead author, has spent almost 40 years studying the impact of climate change on marine organisms.

He said: “I was working at the Rothera Research Station on the Antarctic peninsula in 2017 when there was an extreme freshening event. I was interested in the effect this would have on one of the region’s largest amphipods, and we found that even if the water is diluted fractionally, the amphipods lose their salts, gain water and their gills are damaged.

“This is important for the whole planet as while Antarctica and its wildlife are wonderful, they are also essential to a functioning environment. Damaging the Antarctic damages us all, and if there is freshening it will not have to be very strong before the health of many invertebrate species will be severely impacted.”