Creator: Andre Meyer
Credit: Getty Images/iStockphoto

Climate change affects not just large, cold-adapted animals in the arctic like polar bears, but also the small creatures that live in warmer climates. Numbats (Myrmecobius fasciatus) are small marsupials native to Australia that are greatly affected by the warming temperatures. Numbats are the only marsupials in Australia that are only active during the day when temperatures are at their highest. These adorable squirrel-like animals forage for termites that live in the ground and in rotting logs. Since termites do not provide many calories in their diet, numbats have evolved to conserve body heat that protects them in cooler temperatures. When temperatures exceed 72 degrees, a numbat may spend only about 10 minutes in the sun before overheating, researchers reported in the Journal for Experimental Biology (Cooper and Withers 2024). If temperatures rise above this limit, which often happens with recent rapidly heating global temperatures, a numbat may not have much time to forage during the day at all. Even ducking in the shade during the day is not enough to help keep numbats cool. The research team studying numbat foraging activity, calculated that only 18% of the heat rising a numbat’s internal body temperature, comes from direct sunlight. The high air temperatures and heat trapped in the ground also warm the numbat’s body to its limit. A possible solution that numbat’s may try is limiting their foraging to the early morning or late evening to escape the high temperatures during the day. This may only be viable for a limited amount of time until even these cooler times will become too hot if global temperatures continue to rise, and even before then, this may not be enough time to forage and satisfy the animal’s energy needs. This already endangered animal is struggling with the pressure of predation from cats and foxes is now faced with the threat of climate change like many wildlife species around the world. Further research into how the loss of termite foraging will impact numbat populations is a key next step for the conservation of this species.

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Numbats are built to hold heat, making climate change extra risky for the marsupials

Research Source:

C. E. Cooper and P.C. Withers. Implications of heat exchange for a free-living endangered marsupial determined by non-invasive thermal imaging. Journal of Experimental Biology. Vol. 226, January 7, 2024. doi: 10.1242/jeb.246301.

Rising air and water temperatures caused by human-induced climate change can prove deadly for some species of fish. When temperatures get too high, past where many species can tolerate, the fish that cannot adjust to the warmer temperatures will die. High water temperatures means less available oxygen for fish to be able to breathe. Many fish species can temporarily adjust their lifestyles by reducing activity which allows them to consume less oxygen. However, this is only a short-term solution. Many species like the Atlantic Salmon have very active lifestyles and need to use a lot of energy to find food, mate and lay eggs. Higher temperatures can also reduce the chance of survival for fish eggs laid during spawning season. One of the questions I asked myself is “What can be done to help fish species that are sensitive to warmer temperatures?” Fish water-conditioning may be an answer!

Kathryn Smith and her colleagues from Dalhousie University in Halifax, Canada, pumped naturally cooled groundwater into the Wrights River in Nova Scotia in an attempt to provide reprieve from the warming waters to the native Atlantic Salmon. She said that they saw salmon in varying life stages congregating in the cold plumes this cooled water created. 

Smith and her colleagues also tried a pump-less method by rerouting some of the water from the river to cool in a ground trench before returning to the river. This method they said only cooled the water a few degrees Celsius, however, fish were still seen throughout the summer sheltering in the colder water. Creating safe havens for these fish species to stay cool and literally breathe a sigh of relief is only a first step to helping fish survive in a climate warming world. Large areas, especially sensitive breeding areas, will need to be cooled to make the environments these fish are living in comfortable enough so that they can resume normal activity.

Image US Fish and Wildlife Service: Atlantic Salmon (Salmo salar)

Source: Ogasa N (2023) Pumping cold water into rivers could as as ‘air conditioning’ for fish. Science News. https://www.sciencenews.org/article/cold-water-river-salmon-fish-climate