There to stay: invasive filamentous green alga Mougeotia in Lake Kinneret, Israel

Mougeotia sp. (Zygnematales, Charophyta) first appeared in the plankton of Lake Kinneret in 1998. While initially rare, from 2004 onwards it was present in the plankton continuously, forming massive blooms in spring (2005, 2006, 2012) or in winter (2010), clogging fishermen’s nets. Occasionally different morphological and life-cycle forms of Mougeotia were observed. Mougeotia maintained its population under a wide range of water temperatures, nutrient concentrations, solar radiation, pH levels and stratification patterns, making it a highly versatile alga. In multiple regression, year and month as the only predictors explained 36 % of the pattern of Mougeotia biomass. To explain the lack of relationships with the environmental parameters we hypothesize that (1) Mougeotia possesses exceptional physiological plasticity and/or (2) Lake Kinneret may host two or more genetically distinct cryptic species of Mougeotia with different environmental niches. Preliminary molecular determinations suggest that indeed several different species that look alike are present in Lake Kinneret. Both explanations may hinder any inference on Mougeotia - environment relationships and require further confirmation by experimental work.