Giant Kelp

Giant kelp is a large brown alga found in cold, nutrient-rich coastal waters along the Pacific coast of North and South America and in other temperate regions, recognized as the fastest-growing organism among all seaweeds and one of the fastest-growing organisms on Earth, capable of growing up to half a metre in a single day under favorable conditions. It can reach total lengths of over thirty metres, anchored to the rocky seafloor by a root-like holdfast and kept upright toward the sunlit surface by small gas-filled bladders at the base of each blade. Dense stands of giant kelp form underwater forests that provide shelter, food and structural habitat for an enormous diversity of marine life, including fish, invertebrates, seals and sea otters, whose predation on kelp-eating sea urchins helps keep the ecosystem in balance. Kelp forests are sensitive to changes in water temperature and nutrient availability, and prolonged marine heatwaves in recent decades have caused significant diebacks of giant kelp forests in parts of its range, with cascading effects on the many species that depend on them.