A proposal to protect one of the most pristine marine ecosystems on the earth, Antarctica’s Ross Sea, could be jeopardized by growing tensions between Russia and the West, say environmentalists involved in next week’s high-level meeting on the plan.

The plan would put a halt to commercial fishing across nearly 386,000 square miles of the Ross Sea, which is home to an array of wildlife — some believed to be found nowhere else in the world — threatened by fishing and climate change.

The United States is firmly behind the conservation plans, but Russia and Ukraine have repeatedly stalled efforts to create the reserve.

On Monday, representatives from more than 24 countries will meet in Hobart, Tasmania, at the annual meeting of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).

“It’s taken a tremendous amount of time, money and negotiations to get this far,” said Andrea Kavanagh, director of Pew Charitable Trusts Global Penguin Conservation Campaign. “Talk of a Ross Sea marine reserve began over a decade ago, but Russia and Ukraine seem to be employing blocking tactics rather than engaging in earnest negotiation.”

The two countries first blocked plans for the reserve in 2011 but, according to one environmentalist who asked to remain anonymous, CCAMLR negotiations took a downturn in 2013 when Russia granted asylum to National Security Agency whistleblower Edward Snowden, prompting President Barack Obama to cancel a summit with Russian President Vladimir Putin.

Russia’s annexation of Crimea in March this year, followed by international sanctions against Russia in response to the crisis in eastern Ukraine, has since brought relations between Russia and the West to a new post–Cold War low; it’s unlikely that an increasingly belligerent Moscow will be eager to cooperate with Europe and the United States come Monday.

Ukraine stood with Russia to oppose plans for the reserve in 2013, but it’s unclear how Russia’s military involvement in eastern Ukraine will affect Kiev’s stance at the CCAMLR talks this year.

“Many changes have happened between the two countries,” said one Ukrainian scientist, who asked to remain anonymous. “I can’t make a forecast for the coming CCAMLR meeting yet.”

The Antarctic is already showing signs of vulnerability to climate change — the western Antarctic Peninsula is one of the most rapidly warming places on Earth — and scientists are scrambling to understand how a changing climate will affect the critical ecosystems of the Southern Ocean.

At the same time, fish stocks are dwindling all over the world, pushing fishing fleets farther and farther into new territory to find the few stocks that remain.

The first fishing boats arrived in the Ross Sea in 1996, lured by the lucrative toothfish fishery. A dozen nations now fish for remaining stocks of toothfish, a large predatory fish — also known as Chilean sea bass and highly prized by chefs and seafood lovers in the U.S. — that plays a key role in the Ross Sea ecosystem.

Russia and Ukraine currently have permits to fish for toothfish — Russia for six boats, Ukraine for two. Russia took about one-fifth of the total Ross Sea toothfish catch in 2010.

Scientists argue that removing the toothfish will dramatically change the Ross Sea ecosystem — the fish is both predator and prey, feeding on smaller fish and in turn prey for seals, squid and whales, including the Ross Sea killer whales, which scientists say are already in decline.

But fishing nations argue that restrictions that limit the annual toothfish catch to around 3,000 tons already go far enough.

“There are pressures on CCAMLR to focus more on fishing rather than conservation, and that is a continuing concern of the U.S.,” a U.S. State Department official said, speaking on condition of anonymity.

In 2010 more than 500 scientists signed a letter (PDF) calling on the CCAMLR to ban fishing and create a marine reserve in the entire Ross Sea to protect its unique ecology.

The United States and New Zealand separately made the first proposals for the marine reserve back in 2011. But when nations that fish in the Ross Sea, including Russia and Ukraine, raised concerns about the size of the reserve and a fishing ban in key fishing grounds, as well as the scientific basis for conservation in those areas, the U.S. teamed up with New Zealand to develop a new plan.

“We reduced the size of the [proposed] marine protected area [MPA] by a third,” the State Department official said. “It’s still the world's largest MPA, but in order to bring other countries on board and to comply with what the scientific community was telling us, we needed to change the boundaries.”

Most countries were satisfied with the new proposal, but Russia and Ukraine continued to block the plans. In 2013, Russia argued that the CCAMLR didn’t have the legal authority to establish the reserve — an argument that the the U.S. State Department dismisses as “absolutely incorrect.”

Until recent years, the isolation of the Ross Sea protected its fish and wildlife from overzealous fishers. But advances in technology have allowed fishing boats into even the most hostile environments.

“That’s why we have to declare marine reserves, because we can fish everywhere,” said professor Daniel Pauly, marine biologist and fisheries expert at the University of British Columbia in Canada. “Whether it’s the deep seas or stormy, icy waters, they’re all accessible now. We can fish in Antarctica. We can break the ice. We can maintain ourselves in far away places.”

Whales, seals, penguins and countless seabirds fish the waters off the Antarctic coast. When the fish decline, so too do the birds and animals that depend on them for food. Some species, like the Adélie penguin, breed only on Antarctic shores, carried through the breeding season by rich food supplies offshore.

Scientist David Ainley has studied Antarctic penguin colonies since 1968. Much of his work has focused on Adélie penguins. At just 2 feet tall, Adélies are one of the smallest of the Antarctic penguins, but each year they gather in huge numbers to breed on the shores of the Ross Sea.

“The colony stretches 2 kilometers along the shore and also 2 kilometers inland,” Ainley said, describing the spectacle he encounters each year on his visit to the Ross Sea. “It’s very noisy, and it smells like a chicken coop.”

Whales feed offshore, including the fish-eating Ross Sea killer whale. There are seals of various kinds, like the massive leopard seal that preys on penguins throughout the waters of the Antarctic. Several bird species fly overhead: Antarctic petrels, snow petrels and South Polar skuas, a kind of a scavenging bird that eats penguin eggs and small chicks.

Scientists have discovered even more startling creatures deep underwater, like glass sponges, thought to live for hundreds or even thousands of years, and Antarctic coral, which is able to move along the sea floor.

“It’s one of the healthiest functioning ecosystems left on the planet,” says Kavanagh. “We want to preserve it for that reason, but also because we want to use it as a climate reference area. These areas are vital to scientists studying how ecosystems adapt to climate change.”

Early in the 20th century, Argentina, Chile, the U.K., Norway, France, Australia and New Zealand all made claims to Antarctic territories. The 1959 Antarctic Treaty effectively froze those claims, setting the whole continent aside for science and peaceful purposes, halting the ambitions of these claimant nations to secure Antarctica’s territory or resources for themselves.

But those claims still exert an influence on negotiations from time to time, and this is one of those times. Nonclaimant countries see the MPA as a move to exclude them from the claimant territories, and Russia has been the most vociferous on this issue.

Kavanagh sees this defense as an attempt to direct the conversation away from the marine reserve proposal. “The Ross Sea MPA would be established by all of CCAMLR. It wouldn't be a victory for one country, it would be a victory for all of CCAMLR and they would be all be able to participate in the science that takes place in the Ross Sea.”

It's unclear whether Moscow’s resistance is a political power play by a Russia on increasingly tense terms with the West, an economically driven policy to prevent potentially lucrative fishing grounds from being taken out of circulation, or both. The CCAMLR representative to the Russian delegation did not respond to a request for comment.

Either way, environmentalists are concerned about the future of conservation in the Antarctic.

Biologist Daniel Pauly said, “Basically, I view marine reserves as a bit of money in the bank or a bit of gold you bury in the garden for the bad times. Certainly we can be sure that we will not keep anything going if we continue to saw the branch that we sit on.”