As a research specialist at Biosphere 2, I am responsible for the 700,000-gallon ocean and coral raceway systems. I am presenting a poster on the ecological engineering groundwork and opportunities in coral reef research that we have been exploring at Biosphere 2 with our ocean and raceway systems. If you followed the QR code on my poster to get here, here is some further information on what I am presenting.
Abstract
Biosphere 2 serves as a test bed for biome-scale investigations, which can be used to study human impacts on ecosystems and radical methods of ecosystem intervention. The Biosphere 2 Ocean (B2O) is a 2.6-million-liter ocean mesocosm that models a Caribbean reef ecosystem and is the largest experimental ocean on Earth, dedicated to accelerating reef restoration solutions. Leveraging the unique combination of scale and control, we can simulate realistic stress, variability, and functional interactions on the reef. Our heat exchanger, which can change the water temperature by 2°C in 24 hours, gives us a critical level of control to simulate temperature extremes. An array of LED and metal halide lamps provide adjustable lighting for coral growth. Flow cannons increase and control current in conjunction with a vacuum pump powered wave wall. Finally, two smaller, custom-built coral reef raceway systems are utilized as replicates for coral resiliency experimentation, complete with their own recirculating life-support systems (e.g., protein fractionator, fluidized sand filter, heat exchanger, calcium reactor, monitoring system, and LED lights).
While small-scale coral reef resilience research is adept at capturing processes within a simplistic environment, we need to consider how findings from these testbeds scale to the complexity of the ecosystem level before applying them to the ocean, especially in instances of radical interventions. Engineered ocean mesocosms bridge the gap between large-scale display aquariums and research settings, but there is still a lot to learn about how these systems can be engineered to best achieve a realistic coral reef environment and biogeochemistry. Here we present examples of research that can be uniquely conducted in the B2O and discuss the types of research questions that are best suited for scalable ocean systems. Such mesocosm research serves as a critical step toward a holistic understanding of ocean ecosystem regeneration.
Poster
Coral reef ecosystems are threatened by anthropogenic climate change. Increased temperature and atmospheric CO2 cause mass bleaching events and ecosystem degradation which are difficult to recover from. About half of the world's coral reefs have died in the last 30 years, leaving behind skeletons to be overgrown with algae. This is a critical concern because coral reef ecosystems keep the ocean healthy which provides the main protein source for 1 billion people as well as 50-80% of the planet's oxygen. Coral reefs have been on Earth for hundreds of millions of years and have been highly adaptable. However, with the rapid changes in climate we are facing now, they may not survive without some intervention.
A scientific approach to identifying the kinds of interventions that may be most successful is to test them first. Many labs are working with corals to study how individuals respond to certain environmental conditions. We also have data from field studies in the ocean where there has been recovery after dramatic casualties have occurred. But how can we recreate a stress event that encapsulates the complexities of an entire ecosystem without putting the natural ecosystem at risk? We would have to use a mesocosm; an experimental system that examines the natural environment under controlled conditions. That is what the Biosphere 2 ocean is. An ocean mesocosm is an aquarium dedicated to research. Many large aquariums exist for entertainment and we have learned a lot from this industry on how to maintain accurate ocean conditions in a contained space separate from the ocean. Not only can visitors witness the Biosphere 2 ocean, but it is unlike any commercial aquarium because it is designed and used for research with the complexity of nature and the control of a laboratory.
However, it is not easy to understand the intricacies of such a large-scale mesocosm. We can take a step down in simplicity, and study the effects in a raceway before we test in the mesocosm. A raceway is a laboratory-quality, scaled-up reef tank. Keeping a reef tank is a growing hobby and a lot of expertise comes from these hobbyists. However, while a hobbyist's goal may be to have a visually appealing tank with many fish and colorful corals, a raceway aims to bring laboratory quality at a small scale.
Both the mesocosm and raceway are largely unexplored scales of coral reef research. However, they serve as ideal test beds for innovative and risky solutions to restoring resilient coral reefs before they are implemented in nature. This process is referred to as ecological engineering whereby natural processes are used in a scientific, engineered way to solve environmental problems. Mesocosms allow us to follow a systems ecology approach which is a holistic and multidisciplinary approach that studies ecosystems as complex systems with emergent, evolving properties.
In the Biosphere 2 ocean, we have experimented with bioremediation by introducing herbivores endemic to Caribbean reefs to our algae-dominated system which represents a degraded reef. We also tested other restoration techniques by hand-pulling tons of algae and having a blackout period to decrease algae production. These changes are being tracked with sensors and weekly sampling. The Biosphere 2 ocean has a YSI Exo3 Sonde that monitors the temperature, salinity (conductivity), pH, ORP, dissolved oxygen, and total algae (Chlorophyll-a and Phycoerythrin). Researchers also collect samples for microbial and trace metal analysis as well as testing important water parameters weekly (turbidity, phosphorous, nitrate, alkalinity, silica, iron).
We have an upcoming experiment on stress-hardening corals that utilizes the raceways and ocean mesocosm. The plate frame heat exchanger in the Biosphere 2 ocean makes this experiment possible. We can simulate a heat stress event by warming the water to a specific temperature at a desired rate. Similarly, the raceways have temperature controls and can be used as a preliminary experiment to identify temperature tolerant/resilient corals.
Our coral reef lab team is using the B2O to uniquely address the following big ideas:
How do novel interactions among species on restored coral reefs dictate ecosystem health, structure, and function?
Can reef organisms acclimatize and/or adapt rapidly to ocean change? How long does resistance persist, and can it be passed between generations?
How are compounding stressors (e.g., warming, acidification) impacting reef growth (i.e., calcification) at the ecosystem scale?
What technologies and cyber infrastructure are required to successfully restore and monitor coralreef ecosystems and disseminate data?
While the Biosphere 2 ocean and raceway systems are making waves in this novel method of research, there should be an expansion of these scales of research into other laboratories across the world. The B2O is a model Caribbean coral reef ecosystem, but other mesocosms can be created to simulate different reef topographies and species communities. Mesocosm and raceway research are important scales for coral reef research before our interventions reach the natural ecosystem.
In order for these research applications to be successful, the system needs to be reliable and versatile. My role in managing and maintaining these systems has taught me many lessons and I have some advice for those interested in implementing research at the mesocosm and raceway scale. Consider incorporating failsafes at multiple levels. For instance, automation can be a wonderful way to cut down on the demanding manual labor that these systems require, but if a sensor fails to turn off a pump, you risk flooding your system and ruining your experiment. Whenever you can, implement multiple sensors and program algorithms to inform your automated processes. Another aspect of mesocosm and raceway systems should be that they are maintenance-friendly. Often there are parts of the system that need regular cleaning or maintenance done on them. These parts should be easy to valve off temporarily and remove for their maintenance. It is a huge pain to have to disassemble a system that wasn't made maintenance-friendly. Finally, having an adaptable design is important for expanding the types of research and variables you can manipulate using the same system.
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