The ecosystem of a river depends on complex interactions between primary producers, grazers, and predators, which in turn are determined both by the traits of the individual species involved and the physical conditions of the river. River ecologist Dr. Mary Power illustrates these principles by describing how the dominant grazing fishes in a river ecosystem play a critical role in forming the aquascape.

Coastal wetlands are dominated by a variety of plants adapted to a stressful environment. In the absence of a significant number of herbivores, the growth of these plants was thought to be limited only by nutrient availability. Through experiments, Dr. Brian Silliman revealed that salt marshes, like many other terrestrial ecosystems, are mainly controlled by the top-down forces of herbivores and other consumers.

Many rivers of the world have vast seasonal changes in flow rates. Dr. Mary Power leads us in an exploration of Northern California’s Eel River and how the community of herbivores and predators is affected by changes in river flow. Drought years with no winter floods generate a very different ecosystem compared to years with floods. Human-induced water shortage will also have a drastic detrimental effect on river ecology.

Many rivers of the world have vast seasonal changes in flow rates. Dr. Mary Power leads us in an exploration of Northern California’s Eel River and how the community of herbivores and predators is affected by changes in river flow. Drought years with no winter floods generate a very different ecosystem compared to years with floods. Human-induced water shortage will also have a drastic detrimental effect on river ecology.

A discussion of the Chesapeake Bay Watershed, its complex food web, and the challenges of conserving and restoring the bay. Followed by a general discussion on ecology with the lecturers and students attending the 2016 Holiday Lectures, moderated by HHMI vice president of Science Education, Dr. Sean Carroll.

Savannas cover 20 percent of Earth’s surface and much of Africa. The patterns and processes that occur in this globally important biome illustrate core concepts in ecology.

Regular spatial patterns abound in natural systems. Understanding how patterns arise in ecosystems provides insights into how these ecosystems function.

Large herbivores in the African savanna coexist by partitioning ecological niches by time, space, and diet.

Gorongosa National Park in Mozambique provides several examples for how to model the growth of animal populations and then check the models against actual data.

Ecosystems include complex interactions between animals and plants, which can be measured experimentally and investigated using mathematical models.