This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Many of Antarctica's smallest inhabitants have evolved over millions of years so that their body fluids are similar in chemical composition to those of seawater. However, a combination of melting glaciers, increased rain and extreme weather events means that waters in some of the remotest parts of the planet are increasingly being exposed to reduced salt levels.
Scientists refer to this phenomenon as freshening, and a new study has highlighted the impact this could have on species living in the shallow coastal waters off Antarctica. It has led researchers to warn that continued coastal freshening may pose a significant threat to many marine invertebrates living in the region, but it could also change the nature of the global ocean. The research was conducted by scientists at the University of Plymouth and the British Antarctic Survey (BAS) and builds on previous work by the organizations to assess the impact of changing ocean conditions on some of the planet's smallest but most important inhabitants.
John Spicer, a professor of marine zoology at the University of Plymouth and the study's lead author, has spent almost 40 years examining the effects 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 because, 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 is severely impacted." Published in the journal Marine Environmental Research, the new research focused on the giant amphipod species Paraceradocus miersi, which is found in abundance in Antarctic waters and is related to sandhoppers on temperate beaches. Using creatures collected from Ryder Bay on the Antarctic Peninsula, researchers assessed how their body fluids and internal organs responded when exposed to a simulated freshening experiment.
They found that when exposed to reduced salt levels in the water, the species was still able to regulate some of the key chemicals—including calcium—which are critical to its bodily functions. However, its overall regulation of the ions that make up the full concentration of seawater is impaired, meaning the amphipods lose their salts, gain water and their gills are damaged. This, the researchers say, could have led to significant deaths among shallow-dwelling individuals during the 2017 freshening event and other similar events before and after it.
Simon Morley, an ecophysiologist at the British Antarctic Survey and a study co-author, added, "As climate change continues, environments will change beyond the conditions that animals living there can cope with. In the seas around Antarctica, the biggest signal of climate change is the melting of ice, and this is adding large quantities of freshwater into the oceans. This lowering of salinity could have dramatic impacts, reshaping the communities on the seafloor.
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