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Holiday Lectures on Science

HHMI's Holiday Lectures on Science 2016
Ecology of Rivers and Coasts—Food Webs and Human Impacts

Two leading ecologists describe the complex interactions between species and their environment in aquatic ecosystems. Using field experiments, the researchers illustrate how interactions among organisms such as fish, crab, insects, snails, and algae determine the vitality of rivers and coastal ecosystems and how these factors are affected by human activities.

Our speakers this year are:

Mary Power from UC Berkeley and Brian Silliman from Duke University

Lecture 1 – Trophic Cascades in Rivers – Dr. Mary Power

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.

Lecture 2 —Untangling Salt Marsh Food Webs – Dr. Brian Silliman

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.

Lecture 3—Floods, Droughts, and Food Chains – Dr. Mary Power

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 are 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.

Lecture 4—Climate Stress and Coastal Food Webs – Dr. Brian Silliman

We are in the midst of a major die-off of coastal wetlands – what is to blame? Dr. Brian Silliman has studied some possible culprits, such as the overfishing of top predators, pollution, and climate stress. Different coastal ecosystems seem to be variably sensitive to these stresses, which combined with stresses from herbivores, have a huge impact on the health of the ecosystem.

About The Holiday Lectures on Science

The Holiday Lectures on Science series brings current research into the science classroom, helping to bridge the gap between textbook curriculum and exciting new research developments.

Each autumn, leading scientists come to HHMI headquarters, where they speak to an audience of high school students from around the greater Washington, D.C., region. The annual event is an energetic celebration of science, with hands-on activities, lectures, discussion, and lively exchanges between students, teachers, and scientists. The live event is the foundation for a whole range of resources that are nationally distributed to teachers, reaching an audience of millions of students.

Over the more than 20-year history of the program, Holiday Lectures have covered evolution, earth science, virology, and biodiversity, among other topics. The lectures are broadcast live and also made freely available online at BioInteractive.org and on DVD, which can be ordered for free for educators through HHMI’s Order Materials page.

To complement the Holiday Lectures and enhance their usefulness in the classroom, HHMI also produces a wide range of free science education materials, including classroom activities and lesson plans, interactive online modules, animations, apps, and virtual laboratories—all available at www.BioInteractive.org.

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