1. Grupo de ecología y fisiología de fitoplancton; Sección Limnología; Universidad de la República; Iguá 4225 Montevideo 11400 Uruguay
2. Earth and Atmospheric Sciences Department; University of Alberta; 1-26 Earth Sciences Building Edmonton Alberta T6G 2E3 Canada
3. Paleoecological Environmental Assessment and Research Laboratory (PEARL); Department of Biology; Queen's University; Kingston Ontario K7L 3N6 Canada