Sea urchins: endangered kelp forests
Kelp forests are rapidly disappearing due to sea urchins. Here’s what broke the balance: why hedgehogs gobble up kelp.
A real massacre is currently taking place in California . This is the destruction of laminaria, algae also known as kelp . They inhabit the shallows of the Pacific giving life to lush forests, habitat of various fish. Unfortunately, kelp forests have been devoured continuously by local sea urchins for some time . They are leaving a desert instead of forests. Not far away, however, the sea urchins have a peaceful coexistence with the algae. Why then this difference in behavior between areas so close?
Here the scholars have analyzed two different species of sea urchin. Strongylocentrotus purpuratus , purple in color, and Mesocentrotus franciscanus , red in color. They are two species which live in the waters of California and have always cohabited with kelp, except in the place where they devour it. In recent years there has been a marked deterioration. Dan Reed, author of the study, had already noticed this in the 1980s. A probable thesis could be that sea urchins feed on organic forest debris (dead leaves). When these are not available, then the hedgehogs devote themselves to live plants. So the expert and his team recreated a small kelp forest in the laboratory and introduced sea urchins into it.
If the kelp produces enough debris to satisfy the hedgehogs, then they won’t eat the live plants. If there are more hedgehogs than kelp, then the forest is quickly decimated. Here, too, global warming has a large impact, because stress worsens the health of kelp: it grows less, producing less debris. Here begins the process of forest destruction. A tip from scholars is not to replant kelp in the middle, but on the edges of existing forests. A method to give curls what they need.
- Why are sea urchins devouring kelp forests? (focus.it)