{"id":41248,"date":"2023-02-09T00:01:33","date_gmt":"2023-02-09T08:01:33","guid":{"rendered":"https:\/\/hakaimagazine.com\/?post_type=custom_news&p=41248"},"modified":"2023-02-10T10:35:27","modified_gmt":"2023-02-10T18:35:27","slug":"how-did-millions-of-dead-crabs-wind-up-in-the-abyss","status":"publish","type":"custom_news","link":"https:\/\/hakaimagazine.com\/news\/how-did-millions-of-dead-crabs-wind-up-in-the-abyss\/","title":{"rendered":"How Did Millions of Dead Crabs Wind Up in the Abyss?"},"content":{"rendered":"

In 2015, scientists surveying a protected area of seafloor in the Pacific Ocean\u2019s Clarion-Clipperton Zone (CCZ), a region known for its high concentration of the polymetallic nodules sought after by would-be deep-sea miners, came across an eerie sight<\/a>: a mass grave of millions of red crabs<\/a>. This many dead crabs in one place is shocking enough, but at a depth of 4,000 meters, it was a baffling find.<\/p>\n

\u201cIt took us three or four days to actually realize that these are pelagic crabs\u201d\u2014animals that are supposed<\/em> to be much nearer the surface\u2014says Erik Simon-Lled\u00f3, the lead author of a paper documenting the find and a marine biologist at the United Kingdom\u2019s National Oceanography Centre. \u201cIt is a bit embarrassing, but it [was] so unexpected. Nobody had heard of such a massive deposition in the abyss.\u201d<\/p>\n

While red crabs are abundant in the eastern Pacific and are noteworthy for washing up en masse on beaches in California and Baja California, Mexico, finding them at such depth in such numbers is unheard of. Even more bizarre, the grave was 1,500 kilometers offshore. This is so far from the crabs\u2019 spawning areas off the northwestern United States that it would have taken the current at least a year to push them to the point where they eventually sank.<\/p>\n

So many crabs drifting far offshore and sinking to the seafloor would have attracted droves of hungry predators and scavengers, so the scientists aren\u2019t sure how the crabs remained relatively intact. Most creatures on the abyssal seafloor feed on the tiny bits of waste that fall from the surface, making these crabs, in comparison, a fantastic dinner. \u201cGet your forks, mates, we have quality dinner now,\u201d says Simon-Lled\u00f3 with a laugh.<\/p>\n

The researchers suspect the sheer number of crabs involved has something to do with it. Millions of crabs descending to the seafloor are simply too many to be eaten. \u201cSwarms can have millions and millions of crabs, especially when there are perfect conditions for their development, like algal blooms or different climatic events,\u201d explains Simon-Lled\u00f3.<\/p>\n

\"\"<\/a>

Scientists surveyed three different areas, each about 30 square kilometers, and found all of them littered with dead crabs. Photo by National Oceanography Centre<\/p><\/div>\n

The scientists can\u2019t say whether this mass \u201ccrab fall\u201d is just a one-off coincidence or a periodic event. Masses of millions of dead crabs do wash up on beaches every couple of years, so in principle the same could be happening in the abyss but has gone unnoticed until now. That\u2019s Simon-Lled\u00f3\u2019s preferred interpretation, which is supported by the fact that there were two to three times more scavengers in the crab graveyard than in the rest of the scientists\u2019 survey area in the CCZ.<\/p>\n

The researchers calculate that this single event represents one and a half times the carbon flux that the area would normally get in a whole year. The excess carbon will eventually make its way into the food web, supporting a richer ecosystem than we would typically imagine existing here\u2014an ecosystem where deep-sea mining could do a great deal of damage.<\/p>\n

The area where Simon-Lled\u00f3 and his colleagues found the crabs is not being eyed for mining. But Amanda Ziegler, a researcher at UiT the Arctic University of Norway who was not involved in the study, says it is the same kind of habitat as other areas in the CCZ that do have claims for deep-sea mining. \u201cSo it is possible that this kind of crab fall [has] occurred somewhere that might also be a claim area, but that\u2019s hard to say since it\u2019s so difficult to assess such a big area,\u201d she says.<\/p>\n

Trips to the deep sea are expensive, and funding bodies often prioritize mapping a new area over returning to one that is already mapped. So the research team has not been able to return to see the aftermath of the crab fall or to see whether there have been more depositions.<\/p>\n

\u201cOur paper shows that there is more environmental variability than we would think in abyssal areas,\u201d says Simon-Lled\u00f3. \u201cIt also shows how little we know about this environment that we will potentially be mining in a few years.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

In 2015, scientists surveying a protected area of seafloor in the Pacific Ocean\u2019s Clarion-Clipperton Zone (CCZ), a region known for its high concentration of the polymetallic nodules sought after by would-be deep-sea miners, came across an eerie sight: a mass <\/p>\n

…<\/span><\/div>\n","protected":false},"featured_media":41251,"menu_order":0,"template":"","format":"standard","meta":{"_acf_changed":false,"om_disable_all_campaigns":false,"footnotes":""},"categories":[201],"tags":[],"acf":{"hero_video_url":null,"hero_video_caption":"","deck":"The unexpected discovery of a mass grave of red crabs 4,000 meters below the ocean\u2019s surface is puzzling scientists\u2014and raising questions about the ecology of the deep sea.","authors_group":[{"by_group":"by","contributors_group":[36020]}],"word_count_override":"","podbean1":"","podbean2":"","redirect":"","geolocation":null,"related":[16762,31928],"twitterimage":41252,"facebookimage":41250,"twitterdescription":"","edited":[15491],"factchecked":"","code":"","no_old_story_flag":""},"_links":{"self":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/41248"}],"collection":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/types\/custom_news"}],"version-history":[{"count":2,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/41248\/revisions"}],"predecessor-version":[{"id":41264,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/41248\/revisions\/41264"}],"acf:post":[{"embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/profiles\/15491"},{"embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/31928"},{"embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/news\/16762"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/media\/41251"}],"wp:attachment":[{"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/media?parent=41248"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/categories?post=41248"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hakaimagazine.com\/wp-json\/wp\/v2\/tags?post=41248"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}