This book brings together contributions from authors and places around the world, documenting the biodiversity of diatoms, fossil and recent, and the applications of diatoms in a variety of ecological and geographic settings. This volume honors and celebrates the impact of Prof. Dr. Dr. hab. Galina Khursevich´s over 40 years of scientific work in these fields. Galina Khursevich’s work has been international in scope, as she approached problems of freshwater fossil diatom taxonomy, systematics, and evolution, as well as the application of diatoms to solve practical problems of paleoecology and climate change. This book is of interest for all readers working on fossil or recent algae.