Wetlands! Wetlands! Wetlands! - Stuff You Should Know Recap

Podcast: Stuff You Should Know

Published: 2026-03-20

Guests: Tom Peterman

What Happened

Wetlands are critical ecosystems that occupy only 5% of the United States' land surface but support a remarkable 31% of the country's plant species. They are vital habitats for one third of America's threatened or endangered species, making their conservation a priority for biodiversity.

Historically, the lower 48 states had 220 million acres of wetlands in the 1600s, accounting for 11% of the land area. However, from the 1950s, the U.S. began losing wetlands at a rate of 60,000 acres per year, largely due to conversion for agriculture and real estate development.

Wetlands exist on every continent except Antarctica and can vary greatly in their characteristics. Coastal wetlands, such as marshes, serve as transition zones between land and sea, while inland wetlands include swamps, marshes, bogs, and fens, each with unique features and ecological roles.

Hydric soils in wetlands are saturated with water, creating anaerobic conditions that support specially adapted hydrophytic plants. For example, cattails have air channels to their roots, and cord grass excretes salt through its leaves, showcasing the diverse adaptations plants have developed to thrive in these environments.

Wetlands act as natural sponges, mitigating floods by absorbing excess water. An acre of wetlands can hold up to 1.5 million gallons of water, highlighting their importance in flood control and water management.

The filtration capability of wetlands is so effective that they are often referred to as the 'kidneys of the earth'. They naturally filter water by slowing it down, allowing sediments to settle and nutrients to be absorbed by plant roots or broken down by microbes. This function is highly valued, with wetlands like the Congaree Bottomland Hardwood Swamp equated to a $5 million water treatment plant.

Wetlands provide critical habitats for a wide range of wildlife, including fish, birds, and larger predators like alligators. They support 75% of the U.S. commercial fish and shellfish harvest and serve as breeding grounds for 90% of recreational fish caught in the country.

Despite their ecological importance, 75% of U.S. wetlands are privately owned, leaving them vulnerable to being filled in. Implementing local regulations and electing officials who prioritize wetland protection are essential steps to ensure the conservation of these vital ecosystems.

Key Insights