Site: McMurdo Dry Valleys LTER

Credit: MCM LTER

Photosynthetic and mixotrophic eukaryotes are the dominant primary producers in the stratified water columns of the dry valleys lakes. Nutrient amendment experiments have shown that growth of chlorophytes, an obligate photosynthetic phytoplankton group, are stimulated by the addition of nitrogen or phosphorus in Lake Fryxell and nitrogen in Lake Bonney. Conversely, when communities are transplanted to the high light environment of open water moats, chlorophyte abundance and photosynthetic activity declined significantly. These results indicate that climate-related changes have conflicting impacts on phytoplankton communities (increased nutrient input versus lake level rise/expanding moats).