Seitenpfad:
  • Pres­se
  • Blogs und Meer
  • Sci­en­tists are re­turning from the Ata­ca­ma Trench - Blog­post 9 from RV SON­NE

Sci­en­tists are re­turning from the Ata­ca­ma Trench in the East Pa­ci­fic Oce­an - Blog­post 9 from RV SON­NE, April 2, 2018

Die Inhalte dieser Seite sind leider nicht auf Deutsch verfügbar.

Gua­yaquil, April 2, 2018

Uncovering the secrets of the deep-sea ecosystem.

©Sketch by Manfred Schlösser:The research vessel Sonne (1) and the equipment used for sampling the Atacama trench. CTD-watersampler (2), MOCNESS for sampling plankton from different depths (3), deep-sea profiling lander (4), Multicorer for sediment samples (5), Nano-Lander for hadal depths at more than 8000 meters (6), Gravity corer for long sediment cores (7),  sediment lander for in-situ measurement of biological activity at hadal depths (8).
©Sketch by Manfred Schlösser:The research vessel Sonne (1) and the equipment used for sampling the Atacama trench.
CTD-watersampler (2), MOCNESS for sampling plankton from different depths (3), deep-sea profiling lander (4), Multicorer for sediment samples (5), Nano-Lander for hadal depths at more than 8000 meters (6), Gravity corer for long sediment cores (7), sediment lander for in-situ measurement of biological activity at hadal depths (8).

From March 2nd till April 2nd, an in­ter­na­tio­nal team of re­se­ar­chers, led by Pro­fes­sor Ron­nie N. Glud, Uni­ver­si­ty of Sou­thern Den­mark and Dr. Frank Wenz­hö­fer, Max Planck In­sti­tu­te for Ma­ri­ne Mi­cro­bio­lo­gy in Bre­men, were on a 32-day crui­se on the Ger­man re­se­arch ves­sel Son­ne to the Ata­ca­ma Trench in the eas­tern Pa­ci­fic Oce­an. Du­ring their crui­se they collec­ted sam­ples from the wa­ter co­lumn and se­di­ments from the shoul­der and the bot­tom of the 8066 me­ters deep-sea trench. They co­ve­r­ed a tran­sect of 450 ki­lo­me­ters length by sam­pling 10 sites. Sci­en­tists from 15 dif­fe­rent na­ti­ons with a broad ex­per­ti­se in dif­fe­rent sci­en­ti­fic fiel­ds joi­ned forces to elu­ci­da­te the bio­lo­gy, bio­geo­gra­phy and trans­port pro­ces­ses of this un­char­ted eco­sys­tem. Now they re­port some of their fin­dings.

Biological hot spots

Ron­nie Glud and Frank Wenz­hö­fer both agree that the ex­pe­di­ti­on was a gre­at suc­cess. Their goal is to un­der­stand the trench sys­tem in its who­le. The sci­en­tists collec­ted lar­ge amounts of sam­ples from the seaf­loor and the wa­ter co­lumn. They char­ted the seaf­loor with ba­thy­me­try and re­cor­ded  high-re­so­lu­ti­on vi­de­os and pho­tos. From the­se data, they were able to iden­ti­fy fish spe­cies in se­veral depths. Ron­nie Glud says: “Loo­king at our re­sults from all sites at the Ata­ca­ma Trench, we find a very high bio­lo­gi­cal ac­tivi­ty in the trench. At the bot­tom it was much hig­her than on the shoul­ders. The­se tren­ches are in­de­ed bio­lo­gi­cal hot spots.”

Chief sci­en­tist Frank Wenz­hö­fer says: “On this ex­pe­di­ti­on, we fol­lo­wed a ho­lis­tic ap­proach. To our know­ledge this is the first such ex­pe­di­ti­on to a deep-sea trench of this kind. Our sci­en­ti­fic crew mem­bers are spe­cia­lists on their fiel­ds: ta­xo­no­my, mi­cro­bio­lo­gy, mole­cu­lar bio­lo­gy, bio­geo­che­mis­try and ocea­no­gra­phy. We wan­ted to find out how this deep-sea sys­tem works. Any life in this depth of more than 8000 me­ters has to be ad­ap­ted to the high pres­su­re and to find its ni­che. Our ques­ti­ons were: what are food sour­ces for the com­mu­nities and how is mi­cro­bi­al cy­cling the ele­ments?”

The food web of the trench: From the very small to the big sizes

The start of the food web is the ac­tion of pho­to­syn­the­tic or­ga­nisms in the sun­lit up­per lay­er. The­se mi­cro­sco­pic or­ga­nisms are food for other spe­cies. As the co­as­tal wa­ters of Chi­le and Peru are in­flu­en­ced by sup­p­lies of cold nut­ri­ent rich wa­ter from the deep sea, the growth of the pho­to­syn­the­tic mi­cro­or­ga­nisms should be boosted. As a con­se­quence, the Ata­ca­ma Trench should be­ne­fit from this ma­te­ri­al flow from above. The trench is as­su­med to con­tain lar­ge de­po­sits of or­ga­nic ma­te­ri­al, fun­ne­led down from trench slopes and over­ly­ing wa­ters. In or­der to get the full pic­tu­re, all pro­ces­ses in­vol­ved have to be stu­di­ed.
 
The dif­fe­rent size sca­les ob­ser­ved by the sci­en­tists co­ver a ran­ge of more than 10 bil­li­on: From the mi­cro­sco­pic sca­le with small vi­rus par­ti­cles (1/​10 of a mi­cro­me­ter) to bac­te­ria (mi­cro­me­ter), mei­ofau­na (mil­li­me­ter), ma­cro­fau­na (cen­ti­me­ter), me­gafau­na (me­ter) to trans­port pro­ces­ses across thousands of me­ters. On each of the 10 dif­fe­rent sites in and clo­se to the Ata­ca­ma trench, they collec­ted sam­ples and mea­su­red the oxy­gen pro­files in the wa­ter co­lumn and in the se­di­ments. Oxy­gen is a very power­ful agent used by mi­cro­bes to gain en­er­gy from or­ga­nic mat­ter. The more ac­tive the mi­cro­bes in the se­di­ments, the ear­lier the oxy­gen is used up. This is de­mons­tra­ted by a steep de­cli­ne of the oxy­gen pro­files.

Glud ex­plains: “When com­pa­ring dif­fe­rent sites at 8000 me­ters, the oxy­gen pe­ne­tra­ti­on depth and other pa­ra­me­ters show­ed an un­ex­pec­ted high va­ria­ti­on. That in­di­ca­tes a va­ria­ti­on in bio­lo­gi­cal ac­tivi­ty and lo­cal va­ria­ti­ons in the de­li­very of or­ga­nic mat­ter. We spe­cu­la­te that two main pro­ces­ses are re­s­pon­si­ble for this pat­tern: It can eit­her be a lo­cal va­ria­ti­on in the bio­mass pro­duc­tion in the up­per part of the wa­ter co­lumn, or ma­te­ri­al trans­por­ted from the shoul­ders of the trench by seis­mic ac­tivi­ty.”

Specific questions addressed during this cruise are:

  • What are the sedimentary processes providing food for the hadal community in the Atacama Trench?

  • How do abundance, diversity and community structure of microorganisms, meio- and macrofauna in the Atacama Trench differ from those in less productive trenches and nearby abyssal and shelf sites?

  • What are the general biogeochemical characteristics of the surface and deep sediment and water column in the eutrophic Atacama Trench?

  • Which mineralization pathways are responsible for organic matter breakdown in the eutrophic Atacama Trench?

  • How efficient are microbial communities operating at extreme hydrostatic pressures in mineralizing organic material as compared to their shallower counterparts? And to what extent do specialized, yet unknown extremophile microbial communities mediate these processes?

Fur­ther in­for­ma­ti­on

More details about the project from the Uni­ver­si­ty of Sou­thern Den­mark.

More pictures re­la­ted to the pro­ject.

Ron­nie N Glud at Dan­marks Radio (in Da­nish)

RV SON­NE is a mo­dern Ger­man re­se­arch ves­sel sai­ling main­ly in the Pa­ci­fic Oce­an.
More in­for­ma­ti­on about the ship here.

ERC-Logo
Back to Top