Kelp absorbs carbon dioxide and has high nutritional value, but it is under threat from rising temperatures, pollution and invasive species
Bubbles stream furiously behind Frank Hurd as he gently parts the curtains of giant kelp. Green and gold ribbons reach upwards through the cold waters of the Pacific Ocean towards the sun.
Hurd, a marine biologist with environmental organisation the Nature Conservancy, is diving in a kelp forest off Anacapa Island, one of the protected rocky volcanic islets that form the Channel Islands national park, an archipelago off the coast of southern California.
