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Biosphere 2 and Coral Resistance

Introduction to Biosphere 2

Biosphere 2 is a research facility currently being used to predict the natural environment’s responses to impending climate change. It is entirely enclosed, and contains a variety of replicated aspects of the natural environment, including ocean, mangrove, rainforest, savanna, and fog desert biomes along with a simulated farm where researchers may produce food and raise animals[1].

Photo Credit: Institute of Ecotechnics
Description: Diagram of the Biosphere 2 facility
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Biosphere 2 is located in Oracle, Arizona, and is currently owned by the University of Arizona. Construction for the research center was completed in 1989 by Space Biosphere Ventures, with a layout including three main sections: an airtight, glass-enclosed region, subsurface technology rooms, and habitat areas specifically for researchers. The glass-enclosed sector of Biosphere 2 housed five unique ecosystems including a coastal fog desert, tropical rainforest, savanna grassland, mangrove wetland, and an ocean complete with a coral reef. The subsurface technology rooms were used specifically to measure and maintain biosphere conditions including temperature and humidity, other air systems, and biological waste-treatment systems. These rooms also served as regions of energy creation within Biosphere 2. Lastly, the human habitat areas were largely agricultural, and were used heavily in the facility’s early experiments.

This facility was initially used to study whether self-sustaining communities were possible for further application in space research and colonization. Two initial missions of Biosphere 2 were established to assess the ability of humans to survive in self-sustaining colonies in outer space. The first, beginning in 1991, consisted of eight volunteer crew members—four men and four women—attempting to live completely off of the resources provided by an enclosed Biosphere 2. This experiment continued for two years until Biosphere 2 reached a tipping point; there were an increasing number of issues with decreasing oxygen levels and increasing CO2 levels and the ecosystem failed to produce enough food to sustain all of the crew members. The second of the facility’s first experiments began in 1994 with a crew of seven individuals. However, this experiment ended within that year due to financial issues. It was in this same year that Biosphere 2 began to be leased by Columbia University until 2003. Ownership of the facility shifted until 2011 when it was donated to the University of Arizona, who maintains ownership of the center to this day[1].

Description: Roy Walford, Abigail Alling, Sally Silverstone, Bernd Zabel, Taber MacCallum, Linda Leigh, Van Thillo were the individuals chosen for the original Biosphere mission in 1991.
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Current Experiments

Currently, Biosphere 2 is being used for several different long-term studies regarding the changes within our own natural environment. Some of these studies include researching the responses of different environments, including the simulated biosphere’s ocean/coral reef and tropical rainforest, to climate change. Others include studying landscape evolution, the Moon and Mars habitats, outer space exploration, and agrovoltaics—or the integration of solar panels into agriculture to produce sustainable energy. The facility is also in partnership with other organizations that are conducting a wide range of environmental studies within Biosphere 2.

Due to its nature of being closely simulated from our own natural environment, Biosphere 2 has one of the greatest capacities for studying coral reefs and their responses to climate change. Researchers have already conducted studies on algal removal from reefs, selective breeding to make stronger, more resilient corals that are tolerant to the anticipated future conditions of our natural coral reefs, looking at microbes and the roles they play in keeping reefs healthy, and introducing new herbivorous fish and invertebrates to help with algal removal. After a series of algal removal experiments, scientists also plan to introduce new “super corals” into the reef to revive the ecosystem encompassed within a manipulated ocean. Scientists are also working to study the ability of individual corals to strengthen after stress events, pushing these individual corals just enough to avoid bleaching and recover. These stress tests are repeated and applied throughout a variety of coral species, helping scientists understand the impacts future climate change might have on natural reef environments. In theory, incredibly stress-tolerant coral species could be introduced into the system to make the reef more resilient over time, aiding alongside selective breeding for resilient corals.

Another example of the degree to which scientists may manipulate the conditions within Biosphere 2 may be oceanographer Christopher Langdon’s experiment on the center’s 25 species of coral and how they might respond to various levels of CO2. In his experiment, beginning in 1996, he closely monitored and carefully manipulated the CO2 levels to mimic those of different points in history and perhaps those that corals in the natural environment might experience in the future. From his experimentation, he found that raising CO2 levels to 1200ppm reduced coral reef growth by 90%[2]. This experiment serves as one of many examples of the degree of manipulation researchers within Biosphere 2 may possess over their experiments, closely replicating what might be the responses of real-world ecosystems on change such as that studied in Langdon’s experiment and in the experiments of many other Biosphere 2 researchers.

Photo credit: The University of Arizona
Description: Image of a woman in the Biosphere 2 Ocean/Coral Reef Environment
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Potential for Algal Takeover Research

One of the many threats facing the reefs of our natural world is that of increasing algal cover. Corals and algae often compete for space, and when algae overtakes a reef, it has the potential to smother and kill the existing coral. Such algal takeovers might occur in response to reduced herbivore populations (through overfishing, disease, etc.) or other stressors negatively impacting corals.

Currently, the reefs within the Biosphere 2 ocean are in an algae-dominated state. With this controlled environment, these reefs may serve as crucial vectors in regards to studying strategies of reef restoration, selective breeding, and/or other forms of assisted evolution that might not be tested in the natural environment within what are already incredibly fragile systems. In the near future, researchers are planning on studying these corals’ ability to rebound from their current degraded state through monitoring the reefs’ current conditions and introducing into the system a variety of key species of corals, symbionts, and herbivores, for example, to hopefully help eliminate some of the algae within this deteriorating environment. According to researchers, this future study will occur in three phases: Phase 1, which will consist of monitoring the reef’s current conditions, Phase 2, or the alteration of the reef’s conditions (including introducing key species), and Phase 3, consisting of introducing what will hopefully be what the researchers consider a “super reef” to the projected future conditions of the natural environment in which natural reefs reside[3]. This 3-phase experiment will help scientists understand possible strategies for restoration from algal takeovers in the natural environment’s reefs, aiding these individuals in understanding the impact certain stressors, like increasing algal coverage, might have on fragile yet crucial aspects of our natural world.

All of the steps researchers are taking within Biosphere 2 to understand the ocean’s coral reefs might significantly influence approaches other scientists may take to reef restoration in our own natural environment. Such studies might also help in predicting the responses of reefs to what is projected to occur in the future through what have been closely monitored, highly controlled studies within a simulated environment that is closely similar to our own. From algae takeovers to ocean acidification, researchers have and may continue to understand and implement strategies for reef restoration in Biosphere 2 and, eventually, in the real world’s deteriorating reefs.

In addition to those already taking place within Biosphere 2, future scientists may expand upon current knowledge of events like algae domination over coral reefs through a multitude of potential experiments, including more advanced forms of algae elimination and what could be studies of increasing coral resistance to such algal domination. Within what is almost a copy of the conditions of our own corals in Biosphere 2, scientists may be able to further our abilities to understand the effects of stressors on corals and other aspects of our ocean along with our abilities to construct long-lasting, effective solutions for coral depletion within the natural environment. Though many of the experiments necessary to determine the magnitude of certain stress events are not feasible in natural reef systems, Biosphere 2 serves as a unique opportunity for scientists to test the current and potential abilities of corals to respond to stress.

Photo credit: University of Arizona
Description: Franklin Lane with B2O algae
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The University of Arizona has allowed the general public access to notable Biosphere 2 research, from agrovoltaics to rainforest studies to studies on the system’s ocean and mangroves. Some publications from Biosphere 2’s Ocean[4] and Mangroves systems are outlined below for quick, future reference[5]:

Killam D, Thompson D, Morgan K, Russell M (2023) Giant clams as open-source, scalable reef environmental biomonitors. PLoS ONE 18(1): e0278752. DOI: 10.1371/journal.pone.0278752 Within this study, researchers electronically measured bivalve shells’ opening and closing to serve as a biomonitoring technique. These scientists recorded strong links between the closure frequency of these bivalves and pH/chlorophyll productivity, both of which are factors in algal productivity within the Biosphere 2 Ocean system.

Roach, T.N.F., Little, M., Arts, M.G.I., Huckeba, J., Haas, A.F., George, E.E., Quinn, R.A., Cobian-Guemes, A.G., Naliboff, D.S., Silveira, C.B., Vermeij, M.J.A., Kelly, L.W., Dorrestein, P.C., Rohwer, F. (2020): A multiomic analysis of in situ coral–turf algal interactions . PNAS 117(24): 13588-13595. DOI: 10.1073/PNAS.1915455117 Here, scientists studied the role of holobionts (viruses, bacteria, and their metabolites) in mediating the competitive interactions between coral and turf algae. Overall, these scientists found that specific biogeochemical changes take place at the interface of coral-turf algal interactions that might predict the responses of holobionts to competition.

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): Between control and complexity: opportunities and challenges for marine mesocosms . Frontiers in Ecology and the Environment 14(7): 389–396. DOI: 10.1002/FEE.1313 This article outlines the benefits and drawbacks of mesocosm research, like those studies that are conducted in Biosphere 2. These observations are paired with the inclusion of examples of successful mesocosm research along with suggestions for future avenues of research within these closed systems.

Langdon, C., Broecker, W. S., Hammond, D. E., Glenn, E., Fitzsimmons, K., Nelson, S. G., Peng, T.-H., Hajdas, I., and Bonani, G. (2003): Effect of elevated CO2 on the community metabolism of an experimental coral reef . Global Biogeochemical Cycles 17(1): 1011. DOI: 10.1029/2002GB001941 These scientists worked to manipulate the chemistry of the ocean’s water in Biosphere 2 to mimic that of present-day conditions and those that are predicted in a future condition of doubled CO2. Overall, they concluded that increasing CO2 concentrations in an oceanic environment like that within Biosphere 2 lessens calcification, increases turnover rates of organic carbon, but generally has no effect on net organic production.

Langdon, C., Takahashi, T., Sweeney, S., Chipman, D., Goddard, J., Marubini, F., Aceves, H., Barnett, H., and Atkinson, M. J. (2000): Effect of calcium carbonate saturation state on the calcification rate of an experimental coral reef . Global Biogeochemical Cycles 14(2): 639–654. DOI: 10.1029/1999GB001195 In this experiment, researchers studied the effect of projected environmental changes within seawater on the calcification of coral reef inhabitants. These scientists concluded that saturation state might be a significant factor influencing coral reef calcification. They also found that coral reefs do not seem to be acclimating successfully to a changing saturation state, and they discovered a predicted decrease in coral calcification between 1880 and 2065AD to be 40%. This is an amplified prediction compared to previous hypotheses, so these scientists suggest that reefs may be far more impacted by a changing climate than we may have previously thought.

Atkinson, M.J., Barnett, H., Aceves, H., Langdon, C., Carpenter, S.J., McConnaughey, T., Hochberg, E., Smith, M., Marino, B.D.V. (1999): The Biosphere 2 coral reef biome . Ecological Engineering 13: 147-172. DOI: 10.1016/S0925-8574(98)00096-2 This article provides a deeper insight into the function and composition of the Biosphere 2 coral reef biome, giving readers a more in-depth look into the inhabitants and makeup of the reef itself. Sections within this article go further into detail about the reef’s design, chemistry, and metabolism, serving as a tool for understanding the nature of the reef.

Finn, M., Kangas, P., Adey, W. (1999): Mangrove ecosystem development in Biosphere 2 . Ecological Engineering 13: 173–178. DOI: 10.1016/S0925-8574(98)00097-4 This article gives readers a detailed look at the composition of Biosphere 2’s mangrove system. These authors discuss the similarities between Florida’s mangroves and that of Biosphere 2 and speak more about the overstory, understory, and species composition of Biosphere 2’s mangrove system.


  1. 1.0 1.1 Rogers, K. (2023, March 1). Biosphere 2. Encyclopedia Britannica. In this article, basic background is given on the Biosphere 2, including information about its design, purpose, missions, and its complicated ownership history. It helps readers familiarize themselves with what the facility is and what its purpose is in modern day research.
  2. Cohn, J. (2002): Biosphere 2: Turning an Experiment into a Research Station. Bioscience 52(3): 218-223. This article provides an overview of Biosphere 2’s history, and how it has become the research center that it is today. It focuses particularly on the potential for coral reef experiments explaining why it is such an important leader in coral research. It also touches on the unique opportunity Biosphere 2 presents for long term research and the testing of different solutions.
  3. UA Thompson Lab. (2019, January 3). Biosphere 2 Ocean. Tropical Climate & Coral Reefs Lab. This page explains in-depth future plans for Biosphere 2 experiments regarding algal takeover resilience in the corals of the Biosphere 2 ecosystem. The three-phase experimental plan is also laid out in detail, further explaining the plans of researchers in regards to studying corals within this controlled system.
  4. The University of Arizona (2023). Ocean Reef Lab. The University of Arizona. This site specifically dives into the ocean lab inside the Biosphere 2 and the work it is doing. It talks about specific research projects, some of the resources at their disposal, and the importance of coral research.
  5. The University of Arizona. (2023). Publications. The University of Arizona. This webpage lists publications from the University of Arizona’s Biosphere 2, including studies from multiple of the center’s ecosystems. This page also includes research regarding Biosphere 2 as a whole alongside specific research from each of the simulated biosphere’s biomes.
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