When most people think of "algae", they visualize the mat-forming growth seen on ponds, lakes, and lagoons. This is actually mat-type cyanobacteria and is considered very unhealthy for any waterway. Microalgae, however, are microscopic algae, typically found in freshwater and marine systems. They are unicellular species which exist individually. Unlike higher plants, microalgae do not have roots, stems and leaves. Microalgae, capable of performing photosynthesis, are important for life on earth. They produce approximately half of the atmospheric oxygen and simultaneously use the greenhouse gas, carbon dioxide (CO2), to grow photoautotrophically. These microalgae are considered healthy for any natural waterway.

“A Case for Mixed Algal Cultures”
copied from AlgaeIndustryMagazine.com

Charlotte Dormer writes a review, in the Natural Environment Research Council’s “Planet Earth online”, of research at the University of Cambridge suggesting that, when grown in open ponds, algae should be supplemented with multiple species that help support the algae in some way—making the system less vulnerable to outside influences, such a predators.

The Cambridge scientists say that ecosystems with greater numbers of species are more stable and more resilient to change than monoculture systems made up of just one crop. They coined the term “synthetic ecology” to describe the creation of artificial ecosystems with multiple species.

Problematic Mat-forming “Algae”

  • Bad algae - mat-forming Causes odors and suspended solids problems
  • Excretes toxins
  • Clogs equipment
  • Shades the lagoon and inhibits dissolved oxygen production


  • Non-colonizing and, thus, do not form surface mats
  • Double their population every 24 hours
  • Most microalgae are mobile (swims)
  • Create a pure oxygen environment for bacteria resulting in a symbiotic relationship between microalgae and bacteria
  • Enable the beneficial bacteria population to out-compete the mat algae and duckweed for nutrients, resulting in weed and odor control.


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