Examines the abiotic characteristics of freshwater ecosystems, such as their formation, distribution, and physical/chemical characteristics. Freshwater habitats have long been used as model systems because of their convenient attributes (for example, lakes are largely contained ecosystems with clearly defined edges, and most organisms stay within these aquatic boundaries). Studies how these first principles influence biotic community assembly, drawing on foundational studies that have used freshwater habitats to illustrate dynamics such as seasonal succession, nutrient limitation, trophic cascades, and transitions between alternative states. Examines the linkages between freshwater ecosystems and other ecosystems and the relationship between freshwater systems and the human societies that rely on their ecosystem services.