EU network of mesocosms facilities for research on marine and freshwater ecosystems open for global collaboration.

KOSMOS (Kiel Off-Shore Mesocosms for Ocean Simulations)

KOSMOS-Peru 2020: Effect of changing upwelling intensity on trophic transfer efficiency and export efficiency in the Peru upwelling system. Project Lead: Ulf Riebesell. Timing: February to April 2020 during a KOSMOS experiment in Peru.

Project: Coastal Upwelling in a Changing Ocean (CUSCO)

CUSCO is a coordinated project funded by the German Ministry of Education and Research (BMBF). Project partners include GEOMAR Helmholtz Centre for Ocean Research Kiel (GEOMAR), Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Leibniz Institute for Baltic Sea Research Warnemünde (IOW), University of Bremen, University of Hamburg and Kiel University. The project, which runs from October 2018 to December 2021, is coordinated at GEOMAR (

KOSMOS mesocosm campaign: As part of the CUSCO project (see project description below) a large-scale mesocosm experiment will be conducted in the coastal waters off Callao, Peru, from February to April 2020 using the KOSMOS experimental platform. The experiment will last for 60 days and will investigate the effects of upwelling intensity, simulated by different mixing ratios of surface and deep water on community productivity, food web structure, export and trophic transfer efficiency from primary producers up to small pelagic fish.

Specifically, the KOSMOS experiment will address the following overarching questions:

  • How does upwelling intensity in the HUS scale with plankton community production and what controls the anomalous (out-of-phase with coastal upwelling intensity) seasonal variability?
  • What explains the exceptionally high trophic transfer efficiency (TTE) in the HUS and how is the TTE of energy and biomass from primary producers to small pelagic fish affected by changes in upwelling intensity?
  • What are the effects of changes in upwelling intensity on particle dynamics and how does this influence export flux?
  • Which pathways for transfer of matter and energy are important in the Peruvian coastal zone?

We encourage a wide range of Transnational Access (TA) users to apply: You may come from public authorities, technological partners, and research or teaching institutions. As we plan to observe whole-ecosystem responses, everyone with any complementary expertise is welcome to participate in the KOSMOS are welcome to apply for TA. A total of up to 832 person days will be allocated to external users through Transnational Access provided under AQUACOSM for 2020. It is anticipated that AQUACOSM will support stays of at least 12-14 persons for ca. 60 days, or potentially other combinations.

Practical information: All participants will be accommodated in near-by hostels and private apartments. Lab space will be provided in a rented storehouse. Access to the mesocosms, which will be deployed about 4.5 nautical miles off-shore, will be by small boats operated by the KOSMOS team. In addition to conducting their own research, external users should be prepared to participate in various service activities, including daily sampling at the mesocosms and regular cleaning of the mesocosms. TA users will be supported by the KOSMOS team in all aspects concerning travel, accommodation and logistics on site, transport of equipment and customs clearance. TA users are recommended to stay for the full duration of the experiment.

Project description: Eastern Boundary Upwelling Systems (EBUS), which support the ocean’s most productive ecosystems and are of major importance to global food security, will be impacted by climate change in multiple ways. While upwelling-favourable winds are projected to increase in poleward regions of the EBUS, weakening wind and upwelling strengths are expected in equatorward regions. Stronger upwelling-favourable winds will be counteracted by increased thermal stratification due to surface ocean warming, the net result of which is still uncertain and likely to differ regionally and seasonally. Among the four EBUS the Humboldt Upwelling System (HUS) stands out in several ways. It is not only the largest and, in terms of fish harvest, most productive of the four EBUS, implying exceptionally high trophic transfer efficiency. It also displays a counterintuitive relationship between upwelling intensity and phytoplankton productivity. In view of its dominant role in global fisheries, there is an urgent need to explore the mechanistic links between upwelling intensity and ecosystem productivity and their sensitivity to climate change in the HUS.

No experiment with TA support has been conducted in 2019.

Ocean Artificial Upwelling – Study the feasibility, effectiveness associated risks and side effects of artificial upwelling. Project lead: Ulf Riebesell. 01/09-30/11 2018

We invite external users who are approved for AQUACOSM TA access to join our Ocean Artificial Upwelling KOSMOS experiment off Gran Canaria planned to run from September to November 2018. We welcome experts with any complementary expertise (see below).

A total of at least 390 person days will be allocated to external users in 2018 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 are expected to be conducted in oligotrophic, subtropical waters of Gran Canaria or Cape Verde. Access will be provided to 6-9 users for 50-65 days.

Abstract: The productivity of the ocean is limited by the transport of nutrient-rich deep waters to the sun-lit surface layer. In large parts of the global ocean this transport is blocked by a temperature-induced density gradient, with warm light waters residing on top of heavier cold waters. These regions, which are referred to by scientists as ocean deserts, are presently expanding due to surface-ocean warming. Enhancing the upward transport of nutrient-rich deep waters through artificial upwelling can break this blockade and make these waters more productive. Forced upwelling of deep-ocean water has been proposed as a means to serve three distinctly different purposes: (1) to fuel marine primary production for ecosystem-based fish farming; (2) to enhance the ocean’s biological carbon pump to sequester CO2 in the deep ocean; (3) to utilize the surface to deep-ocean temperature gradient to generate renewable energy via Ocean Thermal Energy Conversion (OTEC). Whereas theoretical and technical aspects of applying artificial upwelling for these purposes have been studied to some extent, the ecological responses and biogeochemical consequences are poorly understood. Ocean artUp therefore aims to study the feasibility, effectiveness, associated risks and potential side effects of artificial upwelling in increasing ocean productivity, raising fish production, and enhancing oceanic CO2 sequestration. 

Objectives: Possible applications of artificial upwelling for the purposes outlined above have their greatest potential in tropical and subtropical regions. As most of these regions are permanently stratified with year-round low productivity, their pelagic ecosystems are adapted to low nutrient supply. Applying artificial upwelling in these environments is likely to induce dramatic changes in the structure and functioning of the local ecosystems, with potentially undesirable side effects on marine life and related ecosystem services. Ocean artUp will investigate the biological and biogeochemical responses to deep-water supply into oligotrophic environments in order to establish a knowledge base for a comprehensive assessment of the feasibility, effectiveness, associated risks and potential side effects of this approach. For this purpose, Ocean artUp will address a variety of key questions at various levels of biological organization.

At the level of primary producers:

  • What phytoplankton composition develops in response to deep-water upwelling?
  • How is this affected by the nutrient stoichiometry (silicon to nitrogen to phosphorus), the rate and mode (pulsed vs. continuous) of nutrient supply, the mixing ratio between deep and surface water and the season?
  • How do these variables affect the efficiency of nutrient utilization?
  • What is the food quality of primary producers for higher trophic levels?

At higher trophic levels

  • What type of food web establishes with how many trophic steps to harvestable fish?
  • What is the transfer efficiency between primary producers/primary consumers and primary/secondary consumers?
  • What is the food quality of secondary producers for higher trophic levels?
  • Under what conditions do low numbers of tropic steps combine with high transfer efficiencies towards high yield of harvestable fish?

Biogeochemical turn-over

  • How does the inorganic carbon to nutrient ratio in the source water affect the in/outgassing of excess CO2?
  • How does the Si:N:P ratio in the source water affect the stoichiometry, sinking, and remineralisation rate of deep water-derived organic matter?
  • How does deep water supply rate, mode of supply and season affect the above processes?
  • What is the export and carbon sequestration potential of artificial upwelling with source waters of different chemical composition?

Associated risks and side effects

  • What is the risk of favouring growth of harmful algae?
  • What is the effect of artificial upwelling on the production of climate relevant gases?
  • Does artificial upwelling pose a risk to ecosystem health in the surrounding environment?
KOSMOS (Kiel Off-Shore Mesocosms for Ocean Simulations)
Legal name of organisation
GEOMAR-Helmholtz Center for Ocean Research Kiel
Organisation address

GEOMAR-Helmholtz Center for Ocean Research

West shore campus
Düsternbrooker Weg 20
D-24105 Kiel

East shore campus
Wischhofstr. 1-3
D-24148 Kiel

Primary contact information (PI)

Professor Ulf Riebesell (KOSMOS)

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Years of Mesocosm Experiments
Description of Facility

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

outdoor mobile – pelagic – marine/brackish
9 floatting structures of 50 m3 (emerging part : 2.5 m high, 2.8 m Ø. submerged part : 17 m high, 2 m Ø)

Controlled Parameters

KOSMOS: CO2, nutrients

Research Topics

KOSMOS: phytoplankton, zooplankton, chemistry, biogeochemistry, ecology

Facility location(s)
Primary interests
Specialist areas
Source of Information
Photos of experiments/installations
KOSMOS mesocosms deployed in Raunefjord off Bergen, Norway in 2011

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


Infrastructure (short name)
KOSMOS (Kiel Off-Shore Mesocosms for Ocean Simulations)
Installation (short name)

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

Coordinates / (routes, areas if non-static)
Water / environmental conditions
Depths / bottom / surface

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 (Fig. 6.6.1). 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 mesocosms prevents wall growth and thus enables long-term experiments that capture plankton seasonal succession and potentially microevolution. The enclosed water encompasses the entire plankton community up to the level of fish larvae and small pelagic fish. Sampling of sedimented matter in combination with frequent 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, CO2 enrichment, 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. The KOSMOS facility was successfully employed in long-term experiments in different climate zones, ranging from the high Arctic (Fig. 6.6.2) to temperate waters in the Baltic and North Sea to oligotrophic waters off Gran Canaria and Hawai’i. These studies, which focussed on the effects of ocean acidification, 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.

Fig. 6.6.1. A KOSMOS mesocosm with flotation frame (5.8 m high, 2.8 m diameter) made of fiber-glass and stainless steel, a flexible bag of thermoplastic polyurethane and a sediment trap at the bottom, which is sampled with a hose descending from the surface.

Fig. 6.6.2. KOSMOS mesocosms off the coast of Ny Ålesund, Svalbard. Photo: S. Klavsen

Fig. 6.6.3. Sampling of the KOSMOS mesocosms from a small boat. Photo: S. Zankl

Instruments / sensors / equipment

KOSMOS: mobile meoscosm structure can be installed on any study site, transportation with RVs and/or in standard 20 and 40-foot containers.

Modality of access

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.

Unit of access
What is available and when
What service and support facilities are available

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. All project participants

  •  have daily access to all mesocosms to carry out their specific measurements during coordinated mesocosm experiments

  •  have unrestricted access to the large data set generated by all participants of the experiment

  •  contribute to obtaining an integrated view of the responses of a complex biological system, the marine pelagic ecosystem

  •  be part of a high-profile, highly visible research project

  •  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

Special rules