Sea Otters Are Saving California’s Intact Kelp Forests Amid Invading “Zombie” Urchins

Sea urchins usually live in harmony with Kelp forests and take pieces of Kelp lying in their safe havens in the rocks. Sometimes, however, they continue to wreak havoc on surviving animals and leave the marine desert known as “urchin barrens”. Not only do kelp forests provide great biodiversity, they are also exceptionally effective at removing carbon at a rate of 20 times the forest area per unit area. What is happening on the California coastline makes a tragedy of global significance. In recent years, large areas of the kelp forest on the west coast have disappeared. We understand a few reasons, but not all. Joshua Smith, a doctoral student at the University of California, Santa Cruz, found that Otter’s feeding choices filled some gaps.

The fall of the corpus forest does not receive the same attention as the damage to the coral wall or the rain forest, but it can be almost as significant. Otters act as guardians of this important ecosystem and prevent them from wiped out by the sea urchin plaza, but marine biologists are surprised that this conservation sometimes fails. Now they think that the choice of otters for hunting large genitals is decisive. 

Creepy forests destroyed when the urchins are so numerous and playful they eat them towards destruction. In healthy northern and central California ecosystems, estimates by sea stars and marine otters ensure that it never gets worse. The door to the Urchin-mystery opened in the 19th century when the Altars were on the verge of extinction, and the real crisis caught in 2013 when a mysterious disease caused the sea star to die-off, leading to the outbreak of the Urchin. Yet, as Smith noted in a statement, the issues are complex. “Here in the Gulf of Monterey we now have a patching mosaic, which looks very healthy with empty algae-free urchin burns without moss.”

The rich kelp forests have remained that way, as many otters tend to feed on sea urchins from other prey, which raises the question of why the same thing did not happen in the next room. Smith’s problem was that in 2014, the Urchins affected by unusually hot water, and without finding a source of regular kelp Detritus, they left home and began eating live instead. The forests quickly denied if the sea stars could not control their numbers. Marine otters increased their ability to swallow urchins and in some places, it was enough. Among others, the urchin barren appeared before the Otter Army mounted a fightback. The wonder of all this is why the otters were not extending their boundaries to the barren, taking enough urchins to re-occupy the empty territory.

Smith learned that the surviving forest contains large gonads of urchins, which otters consider to the tastiest parts of echinoderms. With less kelp to eat in a barren, the genitals of urchins less developed. Otters will not see the point of diving all the way down to collect urchins secretly at the bottom, so once an area is barren the urchins left alone to keep it that way.