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KOSMOS (Kiel Off-Shore Mesocosms for Ocean Simulations)

GEOMAR-Helmholtz Center for Ocean Research Kiel
Infrastructure Description

The Kiel Off-Shore Mesocosms for Ocean Simulations (KOSMOS) are a seagoing mobile platform for mesocosm experiments. They can be deployed from any mid-sized research vessel. KOSMOS comprises 9 free-floating units, each consisting of a floatation frame and a flexible bag 2 m in diameter. After deployment in the sea, the bag unfolds by weights pulling down its lower end to 20 m depth, thereby enclosing an undisturbed water column of 55 m3. The bag is then closed at the bottom by a full-diameter sediment trap. Regular cleaning of the mesocosm walls prevents wall growth and thus enables long-term experiments that capture plankton seasonal succession. The enclosed water encompasses the entire plankton community from bacteria and viruses up to the level of fish larvae and small pelagic fish. Sampling of sedimented matter in combination with measurements of dissolved and suspended matter and air-sea gas exchange can be used for budget calculations of major elements (C, N, P, Si). Potential experimental perturbations include the addition of inorganic nutrients or organic compounds, carbonate chemistry manipulation (i.e. simulating ocean acidification or alkalisation), manipulation of mixed-layer depth, simulation of deep-water upwelling, species exclusion and addition of invasive species.

Sampling devices include depth-integrated and discrete water samplers, nets, gas tight samplers, and sediment samplers. Various sensors continuously record physical and chemical characteristics of the enclosed water along depth profiles. Underwater optical instruments allow for non-invasive in situ quantification of plankton community composition. The KOSMOS facility was successfully employed in long-term experiments in different climate zones, ranging from the high Arctic, temperate waters in the Baltic and North Sea, upwelling ecosystems off Peru, to oligotrophic waters off Gran Canaria and Hawai’i. These studies, which focussed on the effects of ocean acidification, deoxygenation and simulated upwelling on plankton dynamics and biogeochemical cycling, involved researchers from a wide range of scientific fields, including marine and atmospheric chemistry, molecular and evolutionary biology, marine ecology and biological oceanography, aquaculture, fish biology, and biogeochemistry. Results of the KOSMOS experiments have been used in various ecosystem and biogeochemical modelling activities.


KOSMOS mesocosms off the coast of Ny Ålesund, Svalbard. Photo: S. Klavsen

Facility Description

off-shore/outdoor/indoor – pelagic/benthic – marine/brackish


outdoor mobile – pelagic – marine/brackish

9 floating structures of 50 m3 (emerging part : 2.5 m high, 2.8 m Ø. submerged part : 17 m high, 2 m Ø)

Organisation Address

GEOMAR-Helmholtz Center for Ocean Research, West shore campus

Düsternbrooker Weg 20




GEOMAR-Helmholtz Center for Ocean Research, East shore campus

Wischhofstr. 1-3




Infrastructure Address

Seagoing mobile platform operated in moored or free-floating mode by GEOMAR



Information Sources


Media report: Window on future ocean


KOSMOS mesocosms deployed in Raunefjord off Bergen, Norway in 2011Sampling of the KOSMOS mesocosms during an experiment on the effects of ocean acidification off Gran Canaria in 2014KOSMOS deployment with the Spanish research vessel „Hesprides“ off Gran Canaria in 2014


Ulf Riebesell

Andrea Ludwig

Controlled Parameters

KOSMOS: CO2, nutrients

Research Topics

KOSMOS: phytoplankton, zooplankton, chemistry, biogeochemistry, ecology

Experiment Years
TA Support

Services currently offered by the infrastructure: Users have the unique opportunity to participate in multidisciplinary mesocosm experiments carried out in the open sea under close-to-natural conditions. They have daily access to all mesocosms to carry out their specific measurements during coordinated mesocosm experiments and unrestricted access to the large data set generated by all participants of the experiment. Further, users contribute to obtaining an integrated view of the responses of a complex biological system, the marine pelagic ecosystem, and are part of high-profile, highly visible research projects, and interact with leading scientists from a wide range of disciplines.

Support offered under AQUACOSM:

  • Full operation of the KOSMOS facility during experiments

  • Logistical and technical coordination of the research campaign (including transport of equipment)

  • Access to the mesocosms (including boat transfer and sampling support; Fig. 6.6.3)

  • Access to lab facilities

  • Coordinated data exchange and data archiving as well as data workshops

Support offered under AQUACOSM-plus: User support includes (a) full operation of the KOSMOS facility during experiments, (b) logistical and technical coordination of the research campaign (including transport of equipment, on site ordering of consumables, research permissions by local authorities, customs clearance), (c) lab space in land-based facilities at the respective study location, (d) access to KOSMOS sampling gear and incubation equipment, (e) access to KOSMOS boats, diving equipment (provided that users are certified boat drivers and research divers) and safety equipment, (e) daily access to the mesocosms (including boat transfer and sampling support) and (f) coordinated data exchange, archiving and data workshops.

TA Modality of Access

Modality of access under AQUACOSM: A total of at least 1170 person days will be allocated to external users in years 2 and 3 of AQUACOSM Transnational Access provision. KOSMOS experiments planned in the next 5 years and already funded include studies on the effects of ocean deoxygenation in oxygen minimum zones of eastern boundary upwelling systems, effects of ocean acidification on oligotrophic pelagic systems, and the potential of artificial upwelling in raising productivity and fishery harvest in unproductive ‘ocean deserts.’ Experiments in 2018 and 2019 are expected to be conducted in oligotrophic, subtropical waters of Gran Canaria or Cape Verde. Access will be provided to 9 persons for 65 days each year.

Modality of access under AQUACOSM-plus: A total of at least 600 person days will be allocated to external users through TA provided under AQUACOSM-plus. It is anticipated that AQUACOSM-plus will support stays of at least 4-5 persons for 67 days per year in one season within M10-33. Research topics include testing for the suitability of ocean alkalisation for the purpose of carbon dioxide removal. Ocean alkalisation is one of the more promising emerging negative emission technologies. We will conduct a series of experiments to generate a robust database on the ecological and biogeochemical impacts of ocean alkalisation approaches on natural pelagic ecosystems. A KOSMOS in situ mesocosm experiment will be carried out in the coastal waters off Norway (representative for temperate zone neritic systems), and a second KOSMOS experiment will be done in the subtropical oligotrophic waters off Gran Canaria representative for low to mid latitude open ocean conditions.

TA Accommodation

Forschungsverbund Berlin e.V. - Leibniz-Institut für Gewässerökologie und Binnenfischerei
Müggelseedamm 301 and 310
12587 Berlin, Germany