Located near Tucson Arizona in the foothills of the Catalina Mountains, the Biosphere 2 Center was originally developed as an experiment in human habitation. More then a decade later the focus of B2 has shifted dramatically, and the center has come under the guidance of Columbia University's Earth Institute. Today the system operates as one of the worlds largest ecological laboratories covering 3.15 acres and 7.2 million cubic feet of volume. Our work there is housed in the million gallon coral reef mesocosm.

The B2 Ocean is a nearshore tropical hard-bottom community, dominated with macro-algae, coral, fish and infauna, fairly typical of many "degraded" reefs around the world. Over the past 20 years, we have witnessed a nearly monotonic conversion of lush coral reef to fleshy algal reef in the tropical west Atlantic, and at various places across the Indo-Pacific, corellated with reduced species diversity, reduced fish biomass and reduced abundances of invertebrates. These changes in community structure are associated with overfishing, nutrient loading, and climatic shifts. These observations raised grave concerns for the future of coral reefs anywhere near human habitation, even before knowledge of the threats posed by increased atmospheric carbon dioxide.

Healthy reefs constantly recruit new corals so they recover after natural perturbations and algal infestations. Coral recruitment is dependent upon suitable substratum for coral colonization, appropriate coral settlement, and lack of competition from rapidily growing algae. Low nutrients and high fish grazing are believed to favor coral recruitment over algal growth. The Lagoon Ecology research team, supported by Packard funds, is studying the growth of algae and coral under different dissolved carbon dioxide conditions, while the Packard Hydrodynamic group is studying nutrient uptake. Thus the Biosphere 2 coral reef mesocosm offers a unique opportunity to examine the effects of changes in herbivorous fish species composition, changes in inorganic carbon chemistry, and the interaction of these two factors upon the growth, survival, and competitive abilities of stony corals and the living substrata upon which they prefer to settle.