Populations of a centric diatom that produces copious extracellular polymeric substance (EPS), known as ‘lake snow’, have developed in several large microtrophic lakes in New Zealand over the past 10 years. The EPS coats fishing lines and blocks water filters. The phenomenon was first noticed in Lake Wanaka in the early 2000s and has recently been reported in Lakes Coleridge and Wakatipu, with single, isolated historical event...