A thick green carpet can make a pond or reservoir appear almost solid, but giant salvinia is a floating fern, spreading across the water rather than growing from the bottom. In Texas and Louisiana, the plant had become difficult to manage, forming dense mats that blocked sunlight, reduced oxygen and interfered with waterways. According to…

Photo credit: California Department of Fish and Wildlife On a late-August afternoon in the San Gabriel Mountains, a group of hikers near La Verne, California, heard an unsettling sound: what they described as “howling” coming from a large water tank along a trail. When they investigated, they discovered a mother black bear and her two…