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Antarctic depths called possible “cradle of life”

May 16, 2007
Courtesy British Antarctic Survey
and World Science staff

Sci­en­tists have found hun­dreds of new sea crea­tures in a vast, dark deep sur­round­ing Ant­arc­ti­ca. Car­niv­o­rous sponges, free-swim­ming worms, crus­taceans, and mol­luscs liv­ing in the Wed­dell Sea pro­vide new in­sights in­to the ev­o­lu­tion of ocean life, sci­en­tists say.

A type of sea ur­chin known as Cteno­ci­da­ris, whose spines can ex­tend more than 3 inches (7.5 cm). (Cour­te­sy Ar­min Rose/Ger­man Cen­ter for Ma­rine Bio­di­ver­sity)
Re­port­ing in the May 17 is­sue of the re­search jour­nal Na­ture, in­ves­ti­ga­tors de­s­cribed how crea­tures at the bot­tom of the South­ern Ocean—source of much of the world’s deep ocean wa­ters—are like­ly re­lat­ed to an­i­mals liv­ing in both the ad­ja­cent shal­lower wa­ters and in oth­er parts of the deep ocean. 

A key ques­tion is wheth­er shal­low wa­ter spe­cies col­o­nised the deep ocean or vi­ce versa. The re­search find­ings sug­gest the gla­cial cy­cle of ad­vance and re­treat of ice led to an in­ter­min­gling of spe­cies that orig­i­nat­ed in shal­low and deep wa­ter habi­tats, re­search­ers said.

“The Ant­arc­tic deep sea is po­ten­tial­ly the cra­dle of life of the glob­al ma­rine spe­cies,” said lead au­thor An­ge­lika Brandt of the Zo­o­log­i­cal In­sti­tute and Zo­o­log­i­cal Mu­se­um of the Un­iver­sity of Ham­burg. “Our re­search re­sults chal­lenge sug­gestions that the deep sea diver­sity in the South­ern Ocean is poor. We now have a bet­ter un­der­stand­ing in the ev­o­lu­tion of the ma­rine spe­cies and how they can adapt to changes in cli­mate and en­vi­ron­ments.” 

Ka­trin Linse of the Brit­ish Ant­arc­tic Sur­vey added: “What was once thought to be a fea­ture­less abyss is in fact a dy­nam­ic, var­i­a­ble and bi­o­log­ic­ally rich en­vi­ron­ment. Find­ing this ex­tra­or­di­nary treas­ure trove of ma­rine life is our first step to un­der­stand­ing the com­plex re­la­tion­ships be­tween the deep ocean and dis­tri­bu­tion of ma­rine life.”

Three re­search ex­pe­di­tions on a Ger­man re­search ship, as part of a proj­ect called Ant­arc­tic Ben­thic Deep-sea Biodiver­sity, took place be­tween 2002 and 2005. An in­ter­na­tion­al team from 14 or­gan­i­sa­tions stud­ied the sea floor, its con­ti­nen­tal slope rise and chang­ing wa­ter depths to build a pic­ture of the lit­tle known re­gion. They iden­ti­fied over 700 new spe­cies.

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Scientists have found hundreds of new sea creatures in a vast, dark deep surrounding Antarctica. Carnivorous sponges, free-swimming worms, crustaceans, and molluscs living in the Weddell Sea provide new insights into the evolution of ocean life, scientists say. Reporting in the May 17 issue of the research journal Nature, scientists described how creatures in the deeper parts of the Southern Ocean—the source for much of the deep water in the world ocean—are likely related to animals living in both the adjacent shallower waters and in other parts of the deep ocean. A key question for scientists is whether shallow water species colonised the deep ocean or vice versa. The research findings suggest the glacial cycle of advance and retreat of ice led to an intermingling of species that originated in shallow and deep water habitats, researchers said. “The Antarctic deep sea is potentially the cradle of life of the global marine species,” said lead author Angelika Brandt of the Zoological Institute and Zoological Museum of the Un iversity of Hamburg. “Our research results challenge suggestions that the deep sea diversity in the Southern Ocean is poor. We now have a better un derstanding in the evolution of the marine species and how they can adapt to changes in climate and environments.” Katrin Linse of the British Antarctic Survey added: “What was once thought to be a featureless abyss is in fact a dynamic, variable and biologic ally rich environment. Finding this extra ordinary treasure trove of marine life is our first step to un derstanding the complex relationships between the deep ocean and distribution of marine life.” Three research expeditions on a German research ship, as part of a project called Antarctic benthic deep-sea biodiversity, took place between 2002 and 2005. An inter national team from 14 organisations invest igated the seafloor landscape, its continental slope rise and changing water depths to build a picture of the little known region. They identified over 700 new species.