The Ocean's Most Vital Forests Are Disappearing Before Our Eyes

Kelp forests once lined thousands of miles of North America's Pacific coastline, forming dense, cathedral-like ecosystems that supported fish, marine mammals, invertebrates, and seabirds.

Today, large stretches of that habitat are gone—replaced by barren seafloor dominated by sea urchins. The collapse happened fast, and recovery has been slow.

What Kelp Forests Actually Do

These ecosystems are far more than scenery. Kelp forests function as nurseries for commercially important fish species, feeding grounds for sea otters, harbor seals, and gray whales, and refuge for hundreds of invertebrate species. They also buffer coastlines by absorbing wave energy and sequestering carbon.

According to The Marine Diaries, a single kelp plant can grow up to two feet per day and reach lengths of 150 feet, creating vertical structure in the water column that no other organism replicates at the same scale. Lose the kelp, and that entire architecture collapses.

How the Collapse Unfolded

Northern California's kelp forests suffered one of the most dramatic declines on record. Satellite data analyzed by Landsat Science (NASA) showed that bull kelp canopy in the region dropped by more than 95 percent between 2008 and 2019.

Two compounding crises drove that loss. First, a sea star wasting disease beginning around 2013 wiped out sunflower sea stars—the primary predator keeping purple sea urchin populations in check. Then, a massive marine heat wave known as "the Blob" warmed Pacific waters from 2014 to 2016, stressing kelp growth at the same time urchin numbers were exploding without natural control.

The result, detailed by Spear Factor, was the spread of urchin barrens—stretches of seafloor grazed so thoroughly that kelp cannot reestablish even when conditions briefly improve. Urchins in a food-scarce environment enter a dormant, low-metabolism state and can survive for years while preventing any kelp recovery.

The Crisis Has Not Resolved

A decade after the Blob, the situation along much of California's north coast remains dire. Mongabay reports that warming ocean conditions have persisted, and the sunflower sea star—once common from Alaska to Baja California—remains functionally absent from California waters.

Without the sea star to thin urchin populations, kelp that does manage to grow gets grazed down before it can form a canopy. Researchers and coastal communities that depend on kelp-associated fisheries, particularly red abalone and rockfish, are watching a slow-motion crisis with no clear end date.

Restoration Is Possible—But Requires Resources

Targeted interventions have shown results. Removal programs that physically harvest purple urchins from barrens have allowed kelp to return in localized areas.

Captive breeding efforts for sunflower sea stars are underway, though reintroduction at scale remains years away. What's clear is that passive recovery is not happening on its own. Restoration requires coordinated federal investment—in monitoring, urchin removal, species recovery, and research into heat-resilient kelp strains—to match the scale of the loss.

The ecosystems, the fisheries, and the coastal communities connected to them are waiting.

Click below to make a difference.