There's A Squid Graveyard Off The Californian Coast

Sea stars feed on a squid carcass on the deep seafloor of the Gulf of California. © MBARI 2012

Off the coast of California, the seabed is scattered with dead squids that perished after an exhausting orgy of breeding and egg-laying. It may seem strange, but it’s a central part of this corner of the ocean’s interconnected food webs.

The sight was first seen in 2012 by researchers at Monterey Bay Aquarium Research Institute who have recently written a paper, published in the Proceedings of the Royal Society B, about the discovery.

In a series of remotely operated submarine dives, the team counted over 60 dead squids some 1,000 meters (almost 3,300 feet) deep in the Cerralvo Trough, a deep basin near the southern end of the Gulf of California.

Along with these squid carcasses were empty squid egg sheets, thin delicate membranes created by female deep-sea squids to carry their thousands of offspring. This led the researchers to believe that all of the squids are females that have been smothered by their own egg sheets.

A deep-sea squid with an empty egg sheet has successfully brooded its eggs, and will soon die and sink to the bottom. © MBARI 2012 

Within a day, all of this mess is usually hoovered up by scavengers, which include a variety of ratfish, acorn worms, brittle stars, sea cucumbers, crustaceans, and sea stars.

“Whale carcasses on the bottom might last in some form for decades. But we don’t know anything about midsize carrion such as squid carcasses,” head biologist Henk-Jan Hoving noted in a statement. “You have to get very lucky to see one – they likely get consumed within 24 hours.”

Fortunately, the egg sheets remain undisturbed, ensuring that the eggs hatch and the squids didn't reproduce in vain. Other studies have suggested that squids actually inject ink into their egg sheets, making them hard to see and less tasty for scavengers and bacterial decomposers.

This all-you-can-eat buffet also helps to regulate the midwater zone of the ocean by speeding up a process known as the "biological pump". The squids eat food in the midwater zone and sink, taking carbon to the seafloor. However, climate change and overfishing are currently screwing with the marine environment, causing fish stocks to decline and squids to expand their range. Although this means the squid population could boom, it could alter the delicate balance of carbon in the deep.

“In this case, the squid may die almost simultaneously, so there may exist pulses of dead squid falling to the seafloor,” added Hoving. “This could have a big impact on the biological carbon pump."

Scavengers, including a deep-sea crab and sea stars, feed on a squid carcass on the seafloor of the Gulf of California.  © MBARI 2012

 

 

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