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Whales and zooplankton, affected by the exploitation of the Arctic

Whales and zooplankton, affected by the exploitation of the Arctic

As sea ice in the Arctic Ocean declines with each successive year of rising global temperatures, it has become easier and more common for companies to venture into the region for fishing, shipping, and oil and gas exploration. Although boats, rigs and other traps of human activity have already moved rapidly into this fragile environment, scientists are only beginning to understand how the light, noise and chemical pollution they bring with them is affecting the Arctic marine ecosystem.

Some researchers began to fill in the gaps, including two teams working in Norway that presented new findings on the behavior of zooplankton, orcas and humpback whales at the Arctic Frontiers 2020 conference in the city of Tromsø in January. Although it may appear that zooplankton have little in common with whales, research shows that creatures at both ends of the Arctic food web are critical to the health of the marine ecosystem. Understanding how the industry affects these animals could help inform policies that govern business activities in the Arctic.

SENSITIVITY TO LIGHT

Tiny zooplankton move in response to light signals during the day. When the sun rises in the morning, they approach the seabed to avoid predators. When the sun sets, they rise to the surface to feed themselves. During the 24 hours of darkness that occur in the arctic winter, a nearly month-long period called the polar night, scientists thought zooplankton simply stopped moving under the sea ice, says Jørgen Berge, a taxonomist and marine biologist at UiT, the University the Arctic of Norway.

But that thinking changed after the winter of 2007–2008, when Berge noticed that zooplankton in the fjords of the Svalbard Archipelago still moved up and down in patterns similar to those that followed when the sun shone. They found that they could still sense and respond to low levels of light from the moon, northern lights, and backlighting from the sun, even under thick layers of ice and snow. "It was a complete surprise for us," says Berge.

In later work, he showed that other Arctic inhabitants, such as shrimp, elkrill, herring, and cod, would also respond to light levels that were orders of magnitude lower than those experienced by similar pet species from other parts of the world. This left him concerned that Arctic animals were more sensitive to artificial light and that exposure to it could change important aspects of their behavior. Such light pollution, which shines with an intensity and composition not found in nature, has been shown to disrupt hormone production and metabolism in many species of vertebrates, including fish and humans.

To investigate, Berge monitored how Arctic animals moved in response to the artificial lights of a single ship - his own research ship. Between places during the polar night of 2019, Berge measured the total mass of marine animals around the ship with the lights on and off. In each case, there was a significant difference. In one location, there were about half of the animals around the boat when the lights were turned on; in another, with a different animal population, the biomass increased with the lights on, a response Berge says is not surprising, because, like moths On land, some marine animals have adapted to be drawn by light rather than repelled by it.

This research, published Thursday in Communications Biology, has strong implications for the fishing industry, Berge says. Norwegian authorities currently collect information on the abundance of fish in the area throughout the year, including during the polar night, and use that information to determine fishing limits. But because these assessments are carried out with artificial lights on, "that could have a strong bias," Berge says. "Our ability to measure and understand and make good predictions about how much can be fished could be based on incorrect input data."

Similarly, Berge believes that no scientific study conducted during the polar night, with the lights on, could be considered an unbiased representation of how animals would naturally behave during that time. "In the dark and in the light, you will get two very different results, and the knowledge about the system will be very different," says Berge. Franz Hölker, an ecologist at the Leibniz Institute for Freshwater Ecology and Inland Fisheries in Germany, who studies light pollution but was not involved in the new work, agrees. He says Berge's findings reflect some of his.

Safety concerns for humans make it impractical to completely ban artificial light in the Arctic, Berge says. "Rather, we need to understand what effects light pollution is causing." In this way, the level of bias in scientific studies and fishery estimates could be quantified and, to some extent, corrected.


WHERE ARE THE WHALES

The need for a greater understanding of the effects of human industry also exists at the other end of the Arctic animal size scale. Although fishing, shipping, and oil and gas activities have expanded rapidly in the Arctic, “we have no idea what whales are doing,” says Evert Mul, Ph.D. student at UiT. "We plan those activities without taking into account the presence, distribution and behavior of the whales."

To help change that situation, Mul and his colleagues at UiT and the Norwegian Institute of Marine Research have tagged 45 killer whales and 30 humpback whales in the past seven years, far more than in previous tagging studies. In doing so, it allowed them to map how these whales interact with human activities that take place in the polar regions for what they say is the first time in this part of the Arctic.

Mul says the team's results, which he hopes to release this summer, show that the whales spent a lot of time in places where there was a lot of shipping traffic, as well as in oil and gas facilities. "And of course, they spend a lot of time near the fishing boats," because they are drawn to the huge amounts of fish that commercial boats harvest, he says. Mul does not add that it is not uncommon to see 50 to 100 whales around a single boat. Attracted by such a concentration of these spectacular animals, boats full of tourists also join the action.

Greg Breed, a biologist and associate professor at the University of Alaska Fairbanks, who was not involved in Mul's work, observed similar confluences in human and whale activity during his own studies in the Canadian Arctic. "They overlap because they are using the same space. ", He says. For example, whales take advantage of ice-free passages cleared by large boats.

Although whales appear to benefit from easy snacking on while swimming near fishing boats, human activity can also harm animals. Many of the cetaceans tagged in Multi's study have visible scars from entanglement in fishing nets or collisions with boat hulls or propellers. Noise pollution can interfere with the complex songs creatures use to communicate, he says. Chemical contamination is another problem. Killer whales already have the highest contamination of polychlorinated biphenyls (PCBs) on land, and modeling has shown that this problem could jeopardize the long-term survival of the Arctic killer whale population.

However, as Breed points out, it is also possible that stressors other than physical injury or pollutants, such as disruptions in the marine food chain linked to warming ocean waters, could have a greater impact on Arctic whale populations. According to the researchers, potential impacts, including those identified by Mul and Berge, should be considered when making decisions about the industry in the Arctic. Like Berge, Mul believes that the best course of action at this point is not to demand drastic bans but rather policies that have an obvious sense, like better regulation of pollutants where whales are most abundant. Mul also emphasizes the need to continue to improve the information scientists have on the magnitude of the problem.

Even with limited knowledge, those planning industrial activities in the Arctic must still be aware of the possibility that their presence could have repercussions, Mul says. He would like industries to at least "have the seasonal distribution of whales at the back of their minds, even as we continue to understand and map the situation." To help with this effort, Mul plans to meet with Norwegian industry leaders to brief them on his results and seek feedback on how he can present the information in a way that is useful to them. "It is very important," he says, "to have at least a basic understanding of what the animals with whom we are going to share this region are doing."


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