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Invasion of the Fire-Bodies: Pyrosome Bloom in the Pacific

Warmer oceans are causing changes so strange, even scientists are scratching their heads. For three years, starting in late 2013, the eastern Pacific Ocean experienced a persistent warm water mass dubbed ‘the blob.’ The blob formed off the west coast of North America, causing record-high temperatures. Warm-water sharks and tuna were spotted off Alaska and tropical sea life reached the Californian coast. The largest toxic bloom of algae on record, stretching the entire West Coast of the United States, shut down crab fishing, costing local economies over $48 million.  Disappearances of important parts of the food chain, like nutritious shrimp-like krill, caused mass die offs of sea life, including otters, whales, fish, and birds. Emaciated seals and sea lions washed ashore by the hundreds, starving at 20 times the yearly average and sickened by the neurotoxic algae. 

This dire scene could be a preview of a world where climate change has advanced, and some research suggests this situation may have been exacerbated by human-induced warming.  However, this winter the warm water mass finally dissipated and ecosystems appeared to stabilize. But one weird exception is confounding marine biologists, grossing out beach-goers, and dismaying fisherman. 

Pyrosomes- squishy, hollow sea creatures native to equatorial waters- are swarming the Pacific coast of North America by the tens of thousands. These translucent invertebrates look like bumpy pinkish sea cucumbers- some types can grow up to 60 feet but they are usually around six inches long.  Their name comes from the Greek for ‘fire-body’ because they are bioluminescent. Pyrosomes cluster in large groups and are ‘colonial:’ each individual is made up of many small multicellular animals called zooids.

Pyrosomes were previously rare (and strange) enough to be nicknamed the “unicorn of the sea”- they usually stay in deep waters up to 700 meters in the open ocean and aren’t well studied. But now these animals are so thick for several hundred feet in the water table that scientists are concerned when they finally decompose they will deplete oxygen in the surrounding water.

The invasion began this winter when pyrosomes appeared in unprecedented swarms from Northern California all the way to Alaska. During one University of Oregon research expedition this May, a net scooped up 60,000 in five minutes. And no one knows why they’re here.

Scientist haven’t determined where the ‘fire-bodies’ came from, when they will go away or what their effect will be.  Pyrosomes filter-feed on phytoplankton, which is also a staple food for krill, and could potentially disrupt food chains.  The unusually warm waters may have caused pyrosomes to flourish far out of their range, but no one knows for sure.  And while the pyrosome swarm is still barely understood, scientists are concerned this startling change signals greater disruptions occurring.

In fishing grounds from Oregon to Alaska, fishermen’s hooks and net are clogged with the tubular bodies of pyrosomes. Many are having a hard time pulling up anything else, crippling fishing operations. Researchers report that any time they or fishermen go out, there are pyrosomes “as far as the eye can see.” The impact on local fishing economies could be significant.

This strange phenomenon is a striking illustration of the unforeseen effects of climate change and the dramatic disruptions ecosystem shifts cause. Whether the pyrosomes’ appearance is a direct result of anthropogenic warming or not, we can expect more bizarre and troubling consequences of climate change, even if we can’t predict them.

Category: Climate Change