Working with numerous undergraduate to postdoctoral students, Walter Adey studied the metabolism of Caribbean coral reefs through much of the 1970s. High levels of photosynthesis and primary productivity driven by wave action and intense sunlight were characteristic of these well developed reefs in spite of the extremely low nutrient levels. This was natural solar bio-energy capture at its best, and Dr. Adey spent much of the 1980s and 90s understanding and developing the biomimicry now called Algal Turf Scrubber® or ATS™.

Fig. A
Fig. A
Constant trade winds and moderate wave action drives open-ocean water across these coral reefs. By measuring oxygen concentration, both day and night, in the water overflowing the reefs, along with current flow rates, it is possible to determine community respiration and photosynthesis. This work was carried out at many reef sites for several years.
  Fig. B
Fig. B   (click to enlarge)
Yearly range of gross primary productivity at four reef-flat sites on St. Croix, at different seasons. Productivity is plotted as a function of the standing algal crop of mostly algal turfs. Combined with similar data from several reefs across the Caribbean, it was possible to demonstrate that the very high levels of primary productivity are light, and not nutrient limited. Clearly there were important lessons in solar energy capture to be learned from these reefs.
 
Fig. C
Fig. C
Experimental apparatus used in the laboratory, to verify the role of wave surge in driving algal turf primary productivity. A research project of postdoctoral students Robert Carpenter and John Hackney, this experiment demonstrated several key elements in the steps to adapt the process of photosynthesis in coral reefs to practical applications such as cleaning wastewater and capturing solar bioenergy.
  Fig. D
Fig. D
Floating screens from the surface to 10m depth in a wide variety of eastern Caribbean coral reefs were harvested weekly, by hand scraping, to demonstrate algal production levels. At 10-20g(dry wgt)/m2/day, production was roughly one-third of the algal turf productivity inferred from oxygen analyses. The very irregular reef surface provided 2-3 m2 of surface/per horizontal m2 to make up the difference.
 
Fig. E
Fig. E
Transfer (biomimicry) of the algal turf scrubbing process to "real world" needs to remove nutrients from polluted waters. With his wife Karen and their company Ecological Systems Technology, Dr. Adey brought in venture capital, and partnered with Aquatic BioEnhancement Systems for ATS R&D, and with the engineering firm HydroMentia, Inc. to bring ATS to the landscape/industrial scale of cleaning water and atmosphere. This Algal Turf Scrubber® (ATS™), designed and built by HydroMentia for the South Florida Water Management District is on Taylor Creek, a tributary of Lake Okeechobee, running through cattle farm country.
  Fig. F
Fig. F (click to enlarge)
Recent research has shown that the ATS growth screen complexity can greatly affect algal productivity. This plot shows that a three-dimensional screen with vertical fibers (dark purple), in a two year study, produced three times as much algal biomass under the same conditions as the traditional flat screen (light green). The diagram also shows that in this environment (mid Chesapeake Bay) temperature, light and substrate affect productivity in a 4:3:3 ratio.


Copyright © 2008-2013, Walter H. Adey, PhD.