Sea cucumbers benefit from bumper Arctic algae crop
Researchers link deep sea algae bounty to Arctic sea ice melt
Sea cucumbers and other deep sea critters that live on the Arctic Ocean’s seabed had a feast this past spring and summer — on algae.
That’s because huge quantities of algae grew on the underside of the sea ice in the central Arctic, due to the increasing cover by melt ponds, which let more light through the ice, and made the algae grow faster.
As that ice broke up and melted, which happened at a record-breaking pace in 2012, the algae sank rapidly to the bottom of the sea, providing a massive food supply for deep sea animals such as sea cucumbers and brittle stars.
Late last summer, a team of international scientists traveled to the central Arctic Ocean to study the algae that grows on the bottom of Arctic sea ice, a Feb. 13 news release from the Alfred Wegener Institute said.
They went there to see if reports that there were fewer algae mats clinging to the underside of the sea ice was true.
On board the research icebreaker Polarstern, in and under the ice, the researchers used a large number of ultra-modern research devices and methods such as camera-guided sampling devices and an under-ice remotely operating vehicle.
Using an ROV, the researchers were able to find lots of remains of ice algae everywhere under the sea ice, the news release said.
They photographed long strands of algae, hanging from the bottom of the ice like hair.
As for the thicker algae mats, they found these at a depth of more than four kilometres.
There, the seabed was littered with clumps of fresh ice algae which had attracted lots of sea cucumbers and brittle stars.
Biologists found the animals were larger than normal and with highly-developed reproductive organs – an indication that they had been eating abundantly for some two months, the new release said.
But while the bounty of algae falling down from the melted sea ice looks good to sea cucumbers and other deep sealife over the short-term, it could produce long-term changes in the habitat, according to a report on the research now published in the scientific journal Science.
“We were able to demonstrate for the first time that the warming and the associated physical changes in the central Arctic cause fast reactions in the entire ecosystem down to the deep sea,” said lead author and researcher Antje Boetius in the news release.
She and the other researchers can’t yet say whether the deep sea algae they observed was one-time phenomenon or will continue in the coming years.
“We still understand far too little about the function of the Arctic ecosystem and its biodiversity and productivity, to be able to estimate the consequences of the rapid sea-ice decline,” Boetius said.