Often described as underwater rainforests and the “lungs of the ocean”, kelp forests line as much as 25% of the world’s coastlines. They provide important shelter and food for fish and other marine life, and are vital for our oceans’ ecosystems. However kelp is under severe threat because of climate change, warming seas and overfishing. We look at projects in California aimed at stemming the decline of kelp including how scientists are growing it in a laboratory to be planted at sea as well as tackling a key cause of kelp degradation - sea urchins.

Presenter: Myra Anubi Producer/reporter: Craig Langran Series Producer: Jon Bithrey Editor: Tom Bigwood Sound mix: Frank McWeeny