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Massive Kelp Die-Off

Relaxing for the day along one of the West Coast’s many gorgeous beaches, you’re likely to find the green-brown blades of California giant kelp or thick-stemmed strands of bull kelp blanketing sections of the sand. The algae, besides acting as a reminder of our state’s magnificent biodiversity, serves an important role in the marine ecosystems of Northern California’s coast. Kelp forests and algal beds are some of the planet’s most productive ecosystems in terms of net primary productivity, averaging around 2500 g/m2/yr (even more productive than a tropical rainforest!). Other than the vital photosynthesis performed by these forests, they also provide a space to protect numerous endemic fish species and other marine life, in the same way that coral reefs do.

Sadly, in the past decade, California’s coastal waters have seen a staggeringly steep drop in kelp forest cover. According to the University of California, Davis, more than 90% of the state’s bull kelp was lost between 2013 and 2017 due to multiple factors. Accompanying this complete ecological collapse has been a sharp decrease of coastal red abalone (-96%) alongside the swift proliferation of purple sea urchins, which have multiplied 60 fold. In 2013, sea-star wasting disease (SSWD) spread among the sea stars that inhabit the West Coast’s kelp forests, leading to the local extinction of the once-plentiful sunflower star along its natural Pacific coast range. Purple sea urchins, now free from their main predator, have spread uncontested up the shoreline all the way to Alaska, over-eating the now essentially-defenseless giant and bull kelp and outcompeting red abalone populations.

Rapid changes in this delicate marine ecosystem, coupled with increasingly volatile oceanic conditions, such as the unusually warm 2015-2016 El Niño season have led to this immense ecological disruption. While research into the long-term effects of this die-off is still ongoing, it is certain that the repercussions will be felt for years to come, both in the region and in surrounding ones, as our planet has lost an important location for carbon sequestration.

With every day bringing unsettling news about our impending climate crisis, it’s important to focus on steps that can be taken to protect what we still have. Researchers at UC Davis’ Bodega Marine Laboratory are looking into ways to manage the rampant purple sea urchin problem, joining forces with the private firm Urchinomics to “explore the possibility of removing sea urchins from their sea floor barrens and fattening them up for market”, in effect creating an industry around farming the out-of-control shellfish. While solutions may seem, and are for the moment, difficult to attain, free divers and scuba divers with a fishing license are encouraged to take part in local “Purple Urchin Removal” events, like the ones organized by the Noyo Center for Marine Science, to help make an impact.

Written by — Josh Kalia

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