Hypothetical types of biochemistry in the late 1960s, these machines are often classed as computers (or computer-guided robots) and filed under "silicon-based life", even though the silicon backing matrix of these processors is not nearly as fundamental to their operation as carbon is for "wet life". Arsenic, which is chemically similar to phosphorus, while poisonous for most life forms on Earth, is incorporated into the biochemistry of some organisms. Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes ("Chrysiogenes arsenatis").
Lake Winnipeg algae threat fossil fuels, development of large urban populations, and an upsurge in land clearing and deforestation. Nitrogen and phosphorus loading from human activity has accelerated eutrophication of certain rivers, lakes, and wetlands in the U.S.A. resulting in loss of habitat, changes in biodiversity and, in some cases, loss of recreational potential. Lake Winnipeg suffers from the rapid absorption of the elements phosphorus, nitrogen, and carbon. Eutrophication processes fuel the growth of blue-green algae, also known by its more correct scientific name cyanobacteria. These bacteria normally appear green in color and can turn blue when the algae (bacteria) blooms are dying. As