Seitenpfad:

Back­ground: Che­mo­syn­the­tic Eco­sys­tems

Background: Chemosynthetic ecosystems in the Deep Eastern Mediterranean Sea

The oce­an bed hosts di­ver­se en­vi­ron­ments ran­ging from de­sert-like deep seaf­loor to rich oa­ses that are pre­sent at seeps, vents, and food falls such as wha­les, wood or kelp. Che­mo­syn­the­tic eco­sys­tems form whe­re che­mi­cal en­er­gy from sub­sur­face geo­lo­gi­cal or mi­cro­bio­lo­gi­cal pro­ces­ses gets avail­able at the seaf­loor. “Che­mo­syn­the­sis” me­ans that or­ga­nisms can uti­li­ze che­mi­cal en­er­gy — in the form of hy­dro­gen, me­tha­ne, hy­dro­gen sulphi­de and iron — to fix CO2 just as plants do, but wi­thout sun­light.
Chemosynthetic giant bacteria and tubeworms populating cold seeps of the E. Med. (Source MARUM, University Bremen)
Of the dif­fe­rent ty­pes of che­mo­syn­the­tic eco­sys­tems known, cold seeps are now among the most geo­lo­gi­cal­ly di­ver­se and wi­de­ly dis­tri­bu­ted sys­tems ex­plo­red to date, and new sites are still being dis­co­ve­r­ed every year. Cold seep struc­tu­res in­clu­de pock­marks (seaf­loor de­pres­si­ons), bri­ne lakes, and mud vol­ca­noes as well as gas vents. They are cal­led “cold seeps” be­cau­se they are in­de­pen­dent of mag­ma­tic heat and hence func­tio­nal­ly dif­fe­rent from hydro­ther­mal eco­sys­tems.
Map of the Mediterranean Sea
Cold seeps of the Eastern Mediterranean. During the expedition MSM 13 we will visit the mud volcano (1) and pockmark area (2) of the Nile Deep Sea Fan and the (3) Anaximander mountains. Another well known site with many chemosynthetic ecosystems is the Olimpi area (4). (Please click on picture for a higher resolution).
Ob­ser­va­ti­on of the Eu­ro­pean con­ti­nen­tal mar­gins using in situ vi­deo and pho­to­gra­phy with deep sub­mer­si­bles pro­vi­ded evi­dence for a wide ran­ge of ac­tive cold-seep eco­sys­tems as­so­cia­ted with flu­id, gas, and mud es­cape struc­tu­res. They of­ten emit me­tha­ne and other hy­dro­c­ar­bons and are co­lo­ni­zed by spe­ci­fic an­ae­ro­bic sub­sur­face mi­cro­bio­ta which use hy­dro­c­ar­bons as an en­er­gy sour­ce and sea­wa­ter sul­fa­te to re­spi­re, thus pro­du­cing high flu­xes of hy­dro­gen sul­fi­de.
The remotely operating vehicle QUEST4000 (MARUM) and autonomous underwater vehicle ASTERx (IFREMER) in action. (Source Max Planck Institute, Bremen)
Videos from cold seeps of the E. Med.
(Source MARUM, University Bremen)
vi­deo#1: Insinc in action
vi­deo#2: Lift opening
Vi­deo #3: Net with tubeworms
Vi­deo#4: Positioning RAC2
Vi­deo#5: S-probe
Vi­deo#6 Sampling Carbonate
Most cold seeps sup­port high­ly pro­duc­tive com­mu­nities con­sis­ting of spe­cia­li­zed ani­mals that can cope with ele­va­ted con­cen­tra­ti­ons of che­mi­cal com­pounds and low oxy­gen le­vels at and be­low the se­di­ment-wa­ter in­ter­face. Among the most re­mar­ka­ble of the fau­na ex­ploit­ing the ab­un­dant che­mi­cal en­er­gy of seeps are lar­ge worms and mus­sels sto­ring bac­te­ri­al sym­bi­onts in their tis­su­es, which pro­vi­de en­er­gy to their hosts.

The Eas­tern Me­di­ter­ra­ne­an Sea hosts many dif­fe­rent ty­pes of cold seeps, whe­re in­ten­se emis­si­on of me­tha­ne oc­curs from ac­tive mud vol­ca­noes and along re­la­ted faults. Du­ring the last de­ca­de, three ma­jor are­as were the fo­cus of mul­ti­di­sci­pli­na­ry crui­ses using sub­mer­si­bles: the Olim­pi mud vol­ca­no field, lo­ca­ted on the Me­di­ter­ra­ne­an Ridge south of Cre­te, the Ana­xi­man­der Moun­ta­ins, south of Tur­key, and the seaf­loor of the Nile Deep Sea Fan (see map). Fresh mud flows, bri­nes, and car­bo­na­te crusts were ob­ser­ved on their sur­faces.
Left: Center of the Amon mud volcano showing signs of recent eruption. Middle: Carbonate crusts form as a result of microbial methane oxidation. Right: Sulfidic muds hosting lots of bivalves. (Source MARUM, University Bremen)
Du­ring our crui­se HO­MER with RV Ma­ria S. Me­ri­an (MS­M13) we will vi­sit the Nile Deep Sea Fan and the Ana­xi­man­der area, to stu­dy the dis­tri­bu­ti­on, in­ter­con­nec­tion and func­tio­n­ing of the fa­sci­na­ting che­mo­syn­the­tic eco­sys­tems in the­se are­as. Also, we will re­co­ver our long term ex­pe­ri­ments de­po­si­ted du­ring ear­lier crui­ses to the Eas­tern Me­di­ter­ra­ne­an such as BIO­NIL in 2006 and ME­DE­CO in 2007. The­se ex­pe­ri­ments have dealt with lar­val co­lo­niza­t­i­on of dif­fe­rent sub­stra­tes, and we are loo­king for­ward to see­ing what ty­pes of ani­mals have sett­led the­re. We are also loo­king at sun­ken woods, ano­ther type of che­mo­syn­the­tic eco­sys­tem, which attracts many enig­ma­tic deep sea ani­mals spe­cia­li­zed on extrac­ting en­er­gy from wood, with the help of their as­so­cia­ted mi­cror­ga­nisms.
Left: Sea urchins grazing on sunken wood. Middle: Wood colonisation experiment (MPI). Right: Larval settlement experiments (IFREMER, UPMC). (Source MARUM, University Bremen)


Further reading

Fou­cher, JP; West­brook, GK; Boe­ti­us, A; Ce­ra­mi­co­la, S; Dup­re, S; Mas­cle, J; Mie­nert, J; Pfann­ku­che, O; Pier­re, C; Pra­eg, D (2009) Structure and Drivers of Cold Seep Ecosystems, OCEA­NO­GRA­PHY 22 (1): 92-109 Sp. Iss. SI MAR

Van­reu­sel, A; An­der­sen, AC; Boe­ti­us, A; Con­nel­ly, D; Cun­ha, MR; De­cker, C; Hil­ario, A; Kor­mas, KA; Mai­gni­en, L; Olu, K; Pa­ch­i­a­da­ki, M; Ritt, B; Ro­d­ri­gues, C; Sar­ra­zin, J; Ty­ler, P; Van Gae­ver, S; Van­nes­te, H (2009) Biodiversity of Cold Seep Ecosystems Along the European Margins, OCEA­NO­GRA­PHY 22 (1): 110-127 Sp. Iss. SI MAR

Jør­gen­sen BB, Boe­ti­us A, 2007. Feast and famine – microbial life in the deep-sea bed. Na­tu­re Mi­cro­bio­lo­gy Re­views, 5, 770-781
 
 
http://ftp.mpi-bremen.de/videodownload/Video_msm13
Back to Top