Thursday April 18, 2024

Scientific American

For almost two years beginning in 2014, the waters along North America’s Pacific Coast endured the largest and longest-lasting marine heat wave ever recorded. Many species were devastated by ocean temperatures up to 2.4 degrees Celsius (4.3 degrees Fahrenheit) higher than normal. Kelp forests off northern California declined by more than 90 percent, an estimated million or more seabirds died, and fisheries closed up and down the coast, costing some fishing communities hundreds of millions of dollars. But one unassuming group of organisms managed to weather the unrelenting heat fairly well—by breaking the rules of biological separation between animals and plants.

Now new research suggests the flexible lifestyle of these organisms could make them crucial to the survival of ocean ecosystems as climate change continues to crank up the heat.

One of the first things many people learn in biology class is that a basic line can be drawn between two of Earth’s main kinds of life. On one side there are the autotrophs, such as plants, which mostly use photosynthesis to make food out of air, water and minerals, using energy they get from light. On the other are heterotrophs, such as animals, which cannot photosynthesize and so must eat other organisms to get energy. That division is a useful starting point—but like any simplified narrative, it leaves out a lot. All over the world there are organisms called mixotrophs that combine both of these strategies.

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