Antarctic krill genes could reveal how they're responding to climate change

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As Antarctic krill face unprecedented challenges in the Southern Ocean, a new project has been launched to better understand these important invertebrates.

Rising temperatures are putting the future of Antarctic krill at risk.

Numbering in the trillions and collectively weighing hundreds of millions of tons, Antarctic krill are among the most numerous animals on Earth.

But rising ocean temperatures are causing the krill's habitat to shrink, forcing populations to contract towards the South Pole. This means it is more important than ever to understand these animals and how they might adapt to climate change.

A new project, known as KRILLGUARD, aims to bolster our understanding of Antarctic krill, and find the best ways to support their survival.

Dr. Matt Clark is a Research Leader at the Natural History Museum and senior member of the KRILLGUARD team.

"It's hard to overstate just how important Antarctic krill are to the ecosystem," Matt says. "As many as 10% of them are fed on by whales alone, while many more are eaten by everything from sea birds to squid."

"As cold water specialists, krill are vulnerable to the effects of the warming Southern Ocean. We hope that by improving our understanding of their genetics, we can find out more about their populations and support decisions to conserve this vital species."

Reconstructing historical DNA

While krill are just a few centimeters long, their genome is enormous. In fact, it's one of the longest animal genomes sequenced to date, coming in 16 times longer than a human's.

The size of the krill's genome means that it was only sequenced for the first time in 2023. Its extreme length is a result of repeated DNA sequences, the purpose of which remains unclear.

The KRILLGUARD researchers have developed "DNA probes" to identify important genes within the krill's sequenced genome. As part of the project, they aim to target 10,000 gene sequences, including those associated with the krill's response to temperature.

They will then compare historical specimens in the Natural History Museum and krill collected more recently by the British Antarctic Survey to see how these genes have changed over the past century. This will hopefully reveal how the species is responding to the Anthropocene.

"While the DNA in historical collections is degraded due to its age, genetics isn't all about DNA," Matt explains. "To fit inside cells, DNA is wrapped around histone proteins, which are a bit like rosary beads on a necklace. When a gene is on, that section of DNA opens up so that the cell can use it to make proteins, and when it's closed, it's wrapped more tightly."

"We're interested in seeing if, based on the pattern of degradation, we can see where these proteins were, as this will tell us which genes were on and off at the time of death. By building up data from the past 100 years, we should be able to see how krill gene expression has changed."

Protecting krill diversity

The project also hopes to resolve an ongoing mystery around krill.

While the invertebrates are currently treated as one large population surrounding the whole of Antarctica, it's possible that they might form distinctive groups. If this is the case, then as the climate warms, some of these subpopulations may be affected more than others.

Humans may also be adding to this impact. Krill is commercially fished for use in food, cosmetics and fertilizers, and if certain groups are being harvested more than others it might affect how the species can tolerate climate change.

"It's possible that the krill that get fished are the ones better adapted to higher temperatures, allowing them to move into open waters," Matt says. "If this is the case, then we might be hampering krill's ability to adapt to rising ocean temperatures by removing the genes from the population that make them able to cope."

The outcome of this research could be used by international bodies such as the Commission for the Conservation of Antarctic Marine Living Resources to better manage the continent's waters.

"In collaboration with Antarctic treaty organizations, we might be able to introduce protected areas where fishing is prohibited. These could preserve krill with useful genetics to help repopulate zones under fishing, and could potentially move from year to year."

"Ultimately, we will provide our results to the treaty organizations, and it's up to them to decide what they want to do with it."

The KRILLGUARD project is set to report its findings over the next few years.

Provided by Natural History Museum

This story is republished courtesy of Natural History Museum. Read the original story here.