Model Systems

Reef Solutions in the Biosphere 2 Ocean


The Biosphere 2 Ocean provides a unique opportunity to develop, test, and deploy solutions to the coral reef crisis.

The Biosphere 2 marine mesocosm is a totally enclosed system and was originally designed to simulates a Caribbean reef.  It is a large tank with a surface area of 35x20 m, from 7 m deep grading to a shallow lagoon partially separated by a fringing reef.  The total water volume of this mesocosm is 2.6 million liters.  Mechanical systems simulate or substitute for natural environmental processes.  Physical and chemical parameters such as mixing, gas exchange, nutrient concentrations, and partial pressure of CO2 can be independently manipulated.   The Biosphere 2 ocean is ideal for testing models of chemical or biological changes on coral reefs.  The core experiment conducted in this facility was to measure the rates of photosynthesis and calcification for three states of the system.  One corresponding to full glacial time (CO2 = 200µatm, CO3 = 355 µmol/kg, pH 8.29), a second to the present day conditions (CO2 = 360 µatm, CO3 = 241 µmol/kg, pH = 8.08) and a third to conditions predicted for the 22nd Century (CO2 = 900µatm, CO3 = 174 µeq/kg pH = 7.89.  These conditions were alternated at 3-month intervals over a three year period. Results from Langdon et al (2000) have shown that rates of coral skeleton calcification decline by 40 % under seawater carbonate concentrations in equilibrium with CO2 in the mid 21st Century atmosphere.

After Columbia University's groundbreaking coral acidification research and a period of neglect, the system started to degrade.  The substrate is now overgrown by algae and cyanobacteria and the original fauna have been lost (except for about 2 dozen very hardy fish).

We are now revitalizing the ocean to create a coral reef tank entirely dedicated to research. It will host diverse physical environments: a turbulent fore-reef with 6-7m vertical relief; a reef crest and back reef with ~2m relief; and a large 1-2m lagoon with diverse substrates. Light, flow, and chemistry will be maintained by a new generation of equipment to be installed in 2018.

Image courtesy  Orbisnon, some rights reserved

Why do Research on Coral Reefs?

In the past few decades, we have lost roughly half the world’s reef coral. Most of the rest will die by midcentury if warming continues unabated. This unprecedented ecological disaster is unfolding rapidly, and the remedy, a sharp cut in global emissions, remains a distant hope. The reefs of the future will not look like those of today, even if they persist through warming. Heat tolerance varies among species and individuals, leading to a loss of diversity as warming intensifies. This variability does provide some hope: hardier corals may form the basis for future reefs which, although reduced in taxa, can still provide the critical services on which so many people depend. If reefs are going to survive, these resistant corals will be critical components.

This crisis is motivating new, urgent efforts to preserve corals, reefs, and the benefits – food, shoreline protection, tourism, cultural touchstones – that they provide for the ~1 billion people who live in their proximity. The science and practice of reef restoration are woefully incomplete and if we are going to save reefs in any form, we must work fast. We identify an acute need for a platform to develop and test novel, even radical, coral reef interventions in ways that do not threaten the planet’s remaining natural reefs. Advancing reef restoration science and practice demands the capability to conceive and test a broad range of approaches, including those that seem radical in historic context. As one example, the methods of assisted evolution aim to optimize coral resistance to heat stress, using selective breeding, microbiome manipulations, and hardening via repeated stress exposures. Another example might be an engineered, modular reef with a reduced or novel species mix, to help coastal communities weather the loss of a local reef that provides food and coastal protection. These novel approaches cannot be tested on natural reefs, due to accessibility, natural disruptions, and tight management of these vulnerable ecosystems. Yet testing is critical if such methods are ever to be used in practice.

Biosphere 2’s experimental ocean offers a unique opportunity to accelerate the science and practice of reef restoration and generate solutions to the global coral reef crisis.

Ocean Surface Plot 2010Why do Coral Research at Biosphere 2?

The Biosphere 2 Ocean holds unique strengths for the study of coral reef restoration and environmental stress. We aim to build a reef that can survive future climate change, at the scale of an ecological community that is sufficiently complex to have its own emergent properties. We will perturb this reef in specific and highly controlled ways, and track the response at unprecedented resolution, from the genomic through the community and biogeochemical scales. We are not bound by existing ecological associations or biogeographical constraints, but can explore whether combining species differently can enhance resilience. These activities cannot be undertaken on a natural reef – the downside for an existing vulnerable ecosystem is too great. Nor can they be done in a small aquarium or a meter-scale mesocosm, which lack the requisite scale and complexity. The scale, control, and accessibility of Biosphere 2 enable us to address completely new questions.

Project description:

We envision a three-phase research program covering 5-8 years. Each phase will be preceded by intensive planning that includes expertise from all scales of reef science: genomic, microbial, organismal, behavioral, community, biogeochemical. We will also engage reef restoration and management professionals so that we understand the challenges they face and they develop familiarity with the novel approaches that we are exploring.

Expected Impacts:

The reef crisis demands an urgent response, or our planet will lose an iconic ecosystem, and hundreds of millions of humans will suffer. If we intend to intervene, we need a safe place to develop and test these interventions. The Biosphere 2 Ocean will allow us to ask new kinds of questions, to explore and apply novel interventions, and – we hope – to materially improve the chances for reef survival.

Ocean Data

Get involved!

We are fortunate to have a great group of volunteers who have been maintaining the ocean tank and are excited to build for its future. We will be working with scientists, aquarists, museum designers, and artists, to ensure that the changes we make help achieve Biosphere 2’s research, outreach and education goals. We would love for YOU to be a part of this transformation. If you would like to volunteer, plan your research project around the ocean, or know of a student or scientist who should be part of this project, let us know! Contact Katie Morgan at



Julie Cole


Ruth Gates


Rebecca Albright


Andrew Cohen


Jeremiah Hackett


Joanie Kleypas


Virginia Weis


Chris Langdon


John Masson


Adrian Munguia-Vega



2016 (Published)

Between control and complexity: opportunities and challenges for marine mesocosms . Sagarin, R.D., Adams, J., Blanchette, C.A., Brusca, R.C., Chorover, J., Cole, J.E., Micheli, F., Munguia-Vega, A., Rochman, C.M., Bonine, K., van Haren, J. and Troch, P.A. (2016): Frontiers in Ecology and the Environment 14(7): 389–396.

2013 (Published)

Sequencing platform and library preparation choices impact viral metagenomes . Solonenko, S. A., Ignacio-Espinoza, J. C., Alberti, A., Cruaud, C., Hallam, S., Konstantinidis, K., Tyson, G., Wincker, P., and Sullivan, M. B. (2013): BMC Genomics 14: 320.

2003 (Published)

Effect of elevated CO2 on the community metabolism of an experimental coral reef . Langdon, C., Broecker, W. S., Hammond, D. E., Glenn, E., Fitzsimmons, K., Nelson, S. G., Peng, T.-H., Hajdas, I., and Bonani, G. (2003): Global Biogeochemical Cycles 17(1): 1011.

2000 (Published)

Effect of calcium carbonate saturation state on the calcification rate of an experimental coral reef . Langdon, C., Takahashi, T., Sweeney, S., Chipman, D., Goddard, J., Marubini, F., Aceves, H., Barnett, H., and Atkinson, M. J. (2000): Global Biogeochemical Cycles 14(2): 639–654.

1999 (Published)

The Biosphere 2 coral reef biome . Atkinson, M.J., Barnett, H., Aceves, H., Langdon, C., Carpenter, S.J., McConnaughey, T., Hochberg, E., Smith, M., Marino, B.D.V. (1999): Ecological Engineering 13: 147-172.