Forests in the sea

As I kick slowly through an amazing underwater setting, I’m surrounded by tall slender stands of seaweed, their golden leaves waving gently as I pass. Wide-eyed fish peek out from the foliage. Nearby, a couple of boorish bachelor sea lions zig-zag through the scene. Hard to believe that the fate of these rich, undersea jungles lies with some cute, furry, air-breathing creatures called sea otters!

But first, a little about these bull kelp forests: If you’ve walked a beach during a minus tide, you’ve surely spied bits of colorful seaweed washed ashore. Some are ragged remnants of bull kelp, a form of algae that can grow as fast as 1.5 feet a day and reach 250 feet in height. Upper leaves seek the ocean’s surface to soak up sunlight for photosynthesis. Thus they grow not far from shore. Huge stands of this “marine algae” thrive in cold waters on the west coast. Unlike land-based trees, kelp does not have embedded roots; instead, each plant is secured by a “hold-fast,” a tangled root system attached firmly to the rocky seafloor.

A big stand of kelp is an underwater zoo, attracting a menagerie of fish, plus representatives of every invertebrate animal group. Mammals like sea lions and whales seek shelter beneath the kelp canopy. Birds such as gulls, snowy egrets, herons, and cormorants use these forests for protection and feeding. Air-breathing sea otters too, make deep dives into the kelp to feed. And it’s those cuddly sea otters that are the heroes of this story! Believe it or not, these furry land-based mammals today play a vital role in saving our ocean’s kelp forest habitats from disaster!

In the not-so-distant past, we humans were the game-changers in the lives of bull kelp communities, as we so often are with other types of natural systems. It all began early in the 20th century, when humans nearly hunted sea otters out of existence for their dense fur. The result? Kelp beds nearly disappeared. Sounds odd? OK, here’s the connection: I already mentioned that bull kelp plants are anchored by their holdfasts: tangled roots fastened to the sea floor. In the endless oceanic feeding chain, spiky sea urchins mercilessly chow down on kelp roots. The result? The entire plant disconnects from its ocean floor habitat and floats off into the dreaded deep where it can’t survive.

Now, enter our furry heroes, those beleaguered sea otters that have finally begun their comeback once it became illegal for humans to hunt them. You see, otters just love to nosh on urchins! And there’s the fortunate connection: more otters on the scene means fewer destructive urchins, which means that these drowned forests are at last making a comeback.

But humans still threaten our kelp communities; things like coastal development, sedimentation, pollution and fishing all take their toll, the latter often messing with the oceanic food chain itself. These days, we need to value our kelp forests more in light of that overabundance of carbon dioxide in our atmosphere that’s responsible for global warming. Like land trees, kelp plants siphon massive amounts of CO2 from the air, sending oxygen back. Any type of help in reducing CO2 can’t be ignored, even if it comes from tall golden forests that thrive well beyond our sight.