The alga Dichotomosiphon tuberosus was first observed in Lake Simcoe in 1978. In 1983 an initial study was undertaken to determine distribution and biomass of the species within the Lake, and the ecological implications associated with its growth. In 1986, a second study was conducted to determine if the distribution or biomass of Dichotomosiphon had changed during the intervening period, as well as to investigate the relationship between algal growth and benthic invertebrate production.