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Hot­spots for bio­lo­gical activ­ity and car­bon cyc­ling on gla­ciers

Jun 13, 2016

Bacteria may play a larger role in the melting of glaciers than previously suspected, according to a paper published in Nature Biofilms and Mi­cro­bi­o­mes. Scientists from Montana State University and MPI Bremen show how the spatial organisation of microbes leads to an efficient transfer of nutrients between organisms and might speed up glacial melting.

 

Hot­spots for bio­lo­gical activ­ity and car­bon cyc­ling on gla­ciers

Gla­ciers cover roughly ten per­cent of Earth’s land sur­face. They are very im­port­ant for our cli­mate, as they store large amounts of fresh wa­ter and con­trib­ute to the re­flec­tion of sun­light from the sur­face of our planet. Gla­cial melt­ing con­trib­utes to sea level rise and re­duces re­flec­tion, thus in­creas­ing global warm­ing.

Life in gla­cial sys­tems is largely mi­cro­bial. However, little is known about the role of mi­croor­gan­isms in biogeo­chem­ical cyc­ling in these eco­sys­tems. The re­cent pub­lic­a­tion takes a close look at how gla­cial car­bon – a food source for bac­teria – moves out of the ice and into the en­vir­on­ment.
Source: Heidi Smith
Heidi Smith hat kürzlich ihre Doktorarbeit über mikrobielle Vielfalt und Kohlenstoffflüsse in schmelzwasserbestimmen Ökosystemen fertiggestellt. Die vorliegende Veröffentlichung beleuchtet, wie Bakterien möglicherweise eine bedeutendere Rolle beim Abschmelzen der Gletscher spielen als bislang vermutet.
The in­ter­na­tional re­search team around Heidi Smith from Montana State Uni­versity (MSU), USA, ap­plied a suite of ana­lyt­ical meth­ods to in­vest­ig­ate the mi­cro­bial com­munity and bio­lo­gical activ­ity on so-called cryo­con­ites in Ant­arc­tica. Cryo­con­ites, which are ba­sic­ally dust particles blown onto a gla­cier, heat up in the sun­light, caus­ing the ice be­neath them to melt and form­ing cyl­indrical holes. “We found a di­verse mi­cro­bial com­munity as­so­ci­ated with cryo­con­ite particles”, says co-au­thor Mar­cel Kuypers, dir­ector at the Max Planck In­sti­tute for Mar­ine Mi­cro­bi­o­logy in Bre­men. Ac­cord­ing to Smith and her col­leagues, the res­ults in­dic­ate that the cryo­con­ite holes provide a mat­rix for cell ar­range­ments in biofilms that im­prove nu­tri­ent trans­fer and con­sti­tute hot­spots of bio­lo­gical activ­ity. “That could in­crease the ac­cu­mu­la­tion of or­ganic mat­ter on these particles and thus re­duce the re­flec­tion of sun­light, caus­ing gla­ciers to melt faster.”

“It’s not that dif­fer­ent from a rock on a gla­cier that ab­sorbs the sun’s en­ergy, heats up and melts the sur­round­ing ice”, adds Christine Fore­man, Heidi Smith’s ad­viser and an as­so­ci­ate pro­fessor of chem­ical and bio­lo­gical en­gin­eer­ing at MSU. “Heidi’s work is im­port­ant be­cause she’s among the first to get dir­ect meas­ure­ments of biofilms on gla­cier sur­faces. We have shown that biofilms trans­fer and cycle car­bon and other nu­tri­ents in these sys­tems, and are eco­lo­gic­ally ad­vant­age­ous for the sur­vival of or­gan­isms in these ex­treme en­vir­on­ments.”
Bet­ter un­der­stand­ing the quant­it­ies of car­bon con­tained within gla­ciers, as well as how much car­bon is be­ing trans­ferred to other eco­sys­tems, could help sci­ent­ists bet­ter model cli­mate change. Sci­ent­ists have long known that or­ganic car­bon trapped for thou­sands of years in gla­ciers serves as a food source for mi­croor­gan­isms and is lib­er­ated as the ice melts. However, Smith’s re­search shows that the fix­a­tion of in­or­ganic car­bon by mi­croor­gan­isms pro­duces or­ganic car­bon that is rap­idly used by neigh­bour­ing mi­croor­gan­isms.

“Our col­lab­or­a­tion with Rachel Foster and Prof. Kuypers at the MPI in Bre­men cata­pul­ted our re­search to a new level. While still a stu­dent, Heidi Smith spent two months at the MPI work­ing with the NanoSIMS group,” Fore­man says. The NanoSIMS (Nano­scale Sec­ond­ary Ion Mass Spec­tro­meter) al­lows for the coup­ling of phylo­gen­etic iden­tity and meta­bolic func­tion of single cells in mixed mi­cro­bial com­munit­ies from the en­vir­on­ment. “Ap­ply­ing NanoSIMS tech­no­logy to an Ant­arc­tic gla­cial sys­tem il­lu­min­ated how the spa­tial or­gan­isa­tion of mi­crobes in biofilms leads to the ef­fi­cient trans­fer of nu­tri­ents between or­gan­isms.”
"I was amazed at the large size of the cy­anobac­terial fil­a­ments and all the at­tached bac­teria since these had been frozen in the gla­cier. To both visu­al­ise and meas­ure how car­bon could be ex­changed between bac­teria and the cy­anobac­teria us­ing NanoSIMS was both power­ful and in­sight­ful", co-au­thor Rachel Foster, formerly from MPI Bre­men, adds.

“It can be hard to con­vey the im­port­ance of mi­crobes be­cause people can’t see them; but they’re the most abund­ant or­gan­isms on Earth”, Heidi Smith com­ments. “Mi­crobes are also typ­ic­ally at the base of aquatic food webs, and are likely go­ing to be the first to re­spond to changes in the eco­sys­tem. In ad­di­tion to the melt and al­ter­ing of ocean eco­sys­tems through run­off from the gla­ciers, there’s also an in­crease in car­bon di­ox­ide, which con­trib­utes to the rising tem­per­at­ures glob­ally.”
Source: Heidi Smith
Blick in eine Probe von einem Kryokonit: Freilebende Bakterien (grün) und solche, die an fadenförmige Cynobakterien (violett) angeheftet sind. Das Cyanobakterium ist Millimeter lang, tausende Bakterien haften ihm an.
Based on a press release by Montana State University.

Original publication

Biofilms on glacial surfaces: hotspots for biological activity
Heidi J Smith, Am­ber Schmit, Rachel Foster, Sten Littman, Mar­cel MM Kuypers, Christine M Fore­man. npj Biofilms and Mi­cro­bi­o­mes 2, 16008
DOI: doi:10.1038/​npj­biofilms.2016.8

Contact
Heidi Smith, hj­s­mith12@gmail.com
Mar­cel Kuypers, mkuypers@mpi-bre­men.de

or the press office
Fanni As­pets­ber­ger, Man­fred Schlösser
presse@mpi-bre­men.de

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