The Destruction of the Kelp
December 14, 2016 9:15 AM   Subscribe

Kelp is a large seaweed that grows in underwater forests along temperate coasts, sustaining many marine species in turn. The Kelp Highway Hypothesis postulates that Pacific Rim kelp forests and the wealth of fish, mammals and birds that they supported sustained maritime hunter-gatherers spreading into the New World 16,000 years ago. Kelp species play an important role in Chinese, Japanese, and Korean cuisines, and fuelled the production of soda ash in the Scottish Highlands and islands until the industry's collapse in the 19th century, which in turn fuelled emigration to North America and beyond. Charles Darwin wrote of the kelp forests of Tierra del Fuego that "if in any country a [terrestrial] forest was destroyed, I do not believe nearly so many species of animals would perish as would here, from the destruction of the kelp".

In October 2016, an ocean heatwave destroyed the last giant kelp forest on the east coast of Tasmania, bringing an end to "an ecosystem that has dominated Tasmania’s east coast for tens of thousands of years". Giant kelp is the world's largest kelp species, with stands up to 45 metres tall.

A few months earlier, a study revealed that 90% of the kelp forests that make up the north-western tip of the Great Southern Reef disappeared off the western coast of Australia between 2010 and 2013, forests which had supported some of the most valuable fisheries in Australia. And a few months before that, US scientists reported that large tracts of kelp forest along the coast from San Francisco to Oregon have vanished over the past two years, with similarly grim implications for fisheries. Around the world, kelp forests are declining as tropical fish species move into warmer waters and eat them.
posted by rory (7 comments total) 30 users marked this as a favorite
In the silver-lining department (though it isn't much of one), if the tropical seaweed Asparagopsis taxiformis could be grown and harvested in these newly warmer waters and fed to cattle, it could reduce agricultural methane emissions significantly.
posted by rory at 9:15 AM on December 14, 2016 [3 favorites]

where's a charismatic mammal superhero when you need one. otters, let's get that supervillain and turn back time!
[on reading some of the articles, I see that it's the giant storm + the nutrient-poor warm water and not some reverse-Penguin supervillain]
The Australian arm of the huge gyre that moves water around the Pacific is the East Australian Current (known to Finding Nemo fans as “the EAC dude”). Traditionally it pushed warm water south along the coast of the mainland before turning east toward South America long before it hit Tasmania.

In recent decades, something has gone awry. The warming global climate has discombobulated this once-reliable system. Huge eddies of hot, nutrient-poor water keep spinning down toward the Tasmanian coast.

Because of this, eastern Tasmania has some of the fastest warming ocean water on earth, rising two to three times faster than the global average. Over the last two decades, says Baron, the ocean has been getting “more and more rapidly mad”. Tiger sharks, marlin and Queensland grouper have all been recorded in places where they have no right to be. This February, one tuna fisherman had caught 500 southern bluefin before their normal season had even begun.

The current is bringing change, but it doesn’t carry the nitrogen that the forests need to fuel their prodigious growth rate.

“You get a double-whammy for the giant kelp. They get stressed because of heat and they get nutrient-starved and that combination is lethal,”
posted by spamandkimchi at 10:48 AM on December 14, 2016 [1 favorite]

The destruction of natural kelp forests makes me sad for the loss of biodiversity. I wonder what this means for kelp farmers. I guess with a proper breeding program you could get heat resistant kelp, but you've still got to worry about nutrients. I figure growing plants without the need for fresh water will be more important with worldwide water instability due to global warming. Imagine kelp farming near the ice free poles as humanity waits/works thousands of years to claw back the habitability of the equatorial regions in the bad warming scenarios. Or in the better warming scenarios, their role in biofuels and as fertilizers could be an important replacement for fossil fuels. Note, I'm no expert here, but GreenWave seems to be.
posted by Mister Cheese at 11:43 AM on December 14, 2016

That kelp farming article is awesome. I want to be a kelp farmer now.
posted by leotrotsky at 1:11 PM on December 14, 2016 [3 favorites]

Tunip is gonna be bummed.
posted by kirkaracha at 2:55 PM on December 14, 2016

Yeah, after watching some of Bren Smith's talks about vertical ocean farming I want to be a kelp farmer too.
posted by Mister Cheese at 3:18 PM on December 14, 2016

on reading some of the articles, I see that it's the giant storm + the nutrient-poor warm water

That was the starting point for the post. When I read that article in October, it hit me hard: I grew up in southeast Tasmania, and used to go camping and day-tripping with my family along the east coast. My Mefi profile for years has said "Occupation: Beachcomber" because walking along empty white sand beaches is part of my fondest memories and my favourite pastime when visiting home. Except they were never empty: they were littered with kelp, which grew in a tangled yellow-green mass off the lichen-red rocks at the end of every beach, like flat noodles swirling in miso soup. A fish-farmer friend would skin-dive in the kelp forests off Bruny Island and surface with buckets of abalone, and share them with us on weekends at his shack. We would fish from his dinghy for flathead that lived in those waters, whose numbers are now declining; I don't know whether this decline will be hastened by warming waters and the loss of kelp, but expect it will.

A lot of attention and dismay has focussed on the devastation of corals along the Great Barrier Reef and elsewhere in recent years, for good reason, but this loss of temperate kelp forests feels just as significant. When climate change deniers crack wise about how it can't be warming because there's still snow, this is what I want to confront them with. I want to take them to a rocky shore and stick their heads in the warm, nutrient-poor water to witness this, and see if they can splutteringly maintain that everything's fine.
posted by rory at 1:47 AM on December 15, 2016

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