WEBVTT - What Animals Reshape Earth's Waterways?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Laurin

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<v Speaker 1>Vogel bomb here. Nutrients, water, and living space are some

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<v Speaker 1>of life's basic needs, so anything that alters their distribution

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<v Speaker 1>is going to be a key factor in our struggle

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<v Speaker 1>for survival. A change the waterways, the landscape, or the

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<v Speaker 1>availability of food, and an entire ecosystem can be reshaped.

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<v Speaker 1>Certain species wield that power to great effect. One of

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<v Speaker 1>the most fascinating topics in biology is the role of

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<v Speaker 1>ecosystem engineers. These are organisms that either directly or indirectly

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<v Speaker 1>alter their physical surroundings in ways that have major impacts

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<v Speaker 1>on the livelihood of other organisms. Take, for example, the

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<v Speaker 1>American alligator. Out in the wild, these big reptiles like

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<v Speaker 1>to make their own swimming pools. Using their snouts and claws,

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<v Speaker 1>they create massive trend known as gator holes in the

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<v Speaker 1>limestone around Florida's Everglades. In short order, they flood with water.

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<v Speaker 1>They also tend to remain full of water even well

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<v Speaker 1>into the dry season, a time when standing water can

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<v Speaker 1>be scarce for other life forms. A gator hole can

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<v Speaker 1>provide a badly needed oasis of frogs and turtles move

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<v Speaker 1>into these convenient little ponds while plants around their rims,

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<v Speaker 1>attracting all kinds of insects. So, as unlikely as it

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<v Speaker 1>may sound, Florida alligators are environmental stewards. They create brand

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<v Speaker 1>new homes for their neighbors and in the process, strengthen

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<v Speaker 1>the biodiversity of the everglades. Other ecosystem engineers leave different marks. Today,

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<v Speaker 1>we're looking at a few that reshape rivers, link ponds together,

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<v Speaker 1>and transform mangrove creeks. Map makers of the world. You'll

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<v Speaker 1>want to keep your erasers handy when these beasties come to town.

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<v Speaker 1>First up beavers. The term busy as a beaver really

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<v Speaker 1>should be considered high. Beavers are hard working rodents. A

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<v Speaker 1>lone one can cut down up to two hundred trees

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<v Speaker 1>in a single year. Famously, they build sturdy homes or

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<v Speaker 1>lodges for themselves out of branches, mud, and other materials.

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<v Speaker 1>They can also make their own large scale ponds by

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<v Speaker 1>damming streams, and this works by creating a backlog of

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<v Speaker 1>water upstream of the dam. The resulting pond not only

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<v Speaker 1>gives beavers a place to build their lodge, it also

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<v Speaker 1>affords easy access to surrounding trees. Often around a foot

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<v Speaker 1>or a third of a meter, of water covers the

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<v Speaker 1>bases of nearby pines and hardwoods that once stood on

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<v Speaker 1>dry ground. As a result, beavers can swim right up

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<v Speaker 1>to these trees. They also like to dig canals that

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<v Speaker 1>branch out of the new ponds, penetrating deep into the

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<v Speaker 1>local forest. These new wetlands provide homes for smaller animals

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<v Speaker 1>like amphibians. Plus, the dams make great natural filters, a

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<v Speaker 1>blocking excess nitrogen from our creeks and streams. However, all

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<v Speaker 1>of the side effects are positive. When a beaver dam fails,

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<v Speaker 1>it's liable to flood towns or farms. The aftermath can

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<v Speaker 1>be expensive. In the southeastern US alone, these floods are

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<v Speaker 1>responsible for an estimated twenty two million dollars a year

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<v Speaker 1>in damages to the timber industry. It's not surprising, then,

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<v Speaker 1>that many people view beavers as pests. If you have

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<v Speaker 1>a beaver problem, do know that humane solutions are out there.

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<v Speaker 1>Next up the adorable yet terrifying hippopotamus. Put a group

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<v Speaker 1>of hippos and a floodplain with lots of nice, soft soil,

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<v Speaker 1>and they'll start reconfiguring the turf. That's because hippos have

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<v Speaker 1>unique skin that needs to be kept wet for most

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<v Speaker 1>of the day or they'll become dehydrated, so they plow

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<v Speaker 1>through the reed beds that ring rivers and lakes, creating

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<v Speaker 1>deep wallows of water and mud that keep them cool

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<v Speaker 1>during hot days. They're too heavy to float or swim,

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<v Speaker 1>so they reshape the soil bed beneath the water to

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<v Speaker 1>walk along it, the tops of their heads poking out. However,

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<v Speaker 1>these wallows don't offer much in the way of food,

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<v Speaker 1>so at night hippos leave their comfy wallows to go

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<v Speaker 1>grazing on dry land, returning before the sun. That daily

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<v Speaker 1>coming and going creates deep depressions in the soil near

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<v Speaker 1>bodies of water, which in turn become channels worn down

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<v Speaker 1>over time. These footpaths can be as much as sixteen

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<v Speaker 1>feet that's five meters wide, and just like gator holes,

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<v Speaker 1>they're quick to fill up with water. Oh what's more,

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<v Speaker 1>hippo highways linking ponds and streams to big rivers can

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<v Speaker 1>also be established. If the area should flood, these connection

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<v Speaker 1>points may become an outlet for surging water. They also

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<v Speaker 1>enable swamplands to expand and under the right circumstances, The

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<v Speaker 1>trench like trails can divert a great deal of sediment

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<v Speaker 1>from rivers into ponds. And that's not all that hippos

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<v Speaker 1>are doing as they go about their business. Pun intended

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<v Speaker 1>fifteen analysis determined that hippo dung is an important source

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<v Speaker 1>of nutrition for at least some of the fish and

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<v Speaker 1>insects that share the animal's native range. Never underestimate the

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<v Speaker 1>power of poop. However, for their size, hippos don't actually

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<v Speaker 1>eat a lot, only about one to one and a

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<v Speaker 1>half percent of their body weight every day. Large cattle

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<v Speaker 1>eat more like two and a half percent, and African

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<v Speaker 1>elephants can eat over four percent, which is no joke

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<v Speaker 1>when you weigh some seven tons. On a typical day,

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<v Speaker 1>an adult elephant will spend twelve to eighteen hours eating,

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<v Speaker 1>which is vital to the ecosystem. Elephant dung is a

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<v Speaker 1>nutritious fertilizer for the soils of Africa. It's also a

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<v Speaker 1>vehicle by which many seeds are dispersed. Furthermore, by knocking

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<v Speaker 1>down trees and eating shrubs, these colossal animals convert forests

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<v Speaker 1>into grasslands, and a two thousand and nine study published

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<v Speaker 1>in the journal Bioscience revealed even more about the transformative

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<v Speaker 1>powers that African elephants have over their habitats. Sort of

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<v Speaker 1>similar to hippos, Elephants are great at building water channels.

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<v Speaker 1>The test herbivores cover the same land routes over and

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<v Speaker 1>over again as they go about finding food and water,

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<v Speaker 1>making trails in the process. Sometimes multiple generations of elephants

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<v Speaker 1>will reuse the exact same footpaths. As time goes by,

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<v Speaker 1>the animals compress the soil, turning their walkways into trenches,

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<v Speaker 1>and when elephants move back and forth between bodies of water,

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<v Speaker 1>their sunken trails become nice conduits. Thus, rivers or ponds

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<v Speaker 1>that were once isolated can be merged via elephant made canals,

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<v Speaker 1>providing inroads for other wildlife to travel. And another study

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<v Speaker 1>of Asian elephant trails in Thailand found that these paths

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<v Speaker 1>can divert monsoon run off into local streams, preventing flooding.

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<v Speaker 1>But enough of mammals and reptiles. A number of crustaceans

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<v Speaker 1>are great diggers, including fiddler crabs, which shelter in tunnels

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<v Speaker 1>measuring up to three feet or more in that's about

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<v Speaker 1>a meter. The holes are quite a construction project. Given

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<v Speaker 1>the fact that most fiddler species are less than two

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<v Speaker 1>inches or five centimeters wide, then there are the various

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<v Speaker 1>species of burrowing crabs of the mangrove swamps and salt

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<v Speaker 1>marshes of the world. The tunnels that these small crabs

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<v Speaker 1>build are liable to weaken the surrounding turf. On mangrove

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<v Speaker 1>swamp shorelines, this has the effect of widening tidal creeks,

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<v Speaker 1>whose mud and clay based banks are rendered more vulnerable

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<v Speaker 1>to erosion by the digging invertebrates. They may also play

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<v Speaker 1>a key role in aerating the marshy soil and kicking

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<v Speaker 1>up nutrients from the beds, and that's just part of

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<v Speaker 1>the story. Because burrowing crabs have such a profound effect

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<v Speaker 1>on sediment composition, their tunnels can also cause completely new

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<v Speaker 1>creeks to form within these mangrove systems, and all of

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<v Speaker 1>this further impacts the plants and other animals that live

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<v Speaker 1>around those environments. Those tiny crabs change how microorganisms in

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<v Speaker 1>places can grow, which changes what foragers and predators come

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<v Speaker 1>to the area. Just another example of how small actions

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<v Speaker 1>can add up to huge effects. Today's episode is based

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<v Speaker 1>on the article Eco engineers five animals that can reshape

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<v Speaker 1>Earth's waterways on how stuffworks dot Com. Written by Mark Vancini.

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<v Speaker 1>Brain Stuff is production by Heart Radio in partnership with

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<v Speaker 1>how stuffworks dot Com and is produced by Tyler Klang.

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<v Speaker 1>Four more podcasts from my heart Radio. Visit the iHeartRadio app,

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