Over the past two weeks, we’ve brought you 10 stories of species in Alabama that are battling extinction. We could bring you 121 more.

That’s how many species are listed as endangered or threatened in Alabama under the Endangered Species Act, according to the U.S. Fish and Wildlife Service.

At 131, Alabama has the third highest number of endangered or threatened species in the country, behind only Hawaii and California.

Alabama has a lot of endangered species because it has a lot of species period. The state typically ranks fifth in terms of overall biodiversity. It’s generally No. 1 in terms of the number of species of freshwater fishes, frogs, crayfish, turtles, mussels and snails.

“Alabama has wound up as one of the most species-rich corners of the planet,” said Scot Duncan, a biology professor at Birmingham-Southern College and author of the book “Southern Wonder: Alabama’s Surprising Biodiversity.”

Alabama’s system of distinct rivers, carving out territory from the Appalachian foothills to the Mobile-Tensaw Delta are a big reason why. Those rivers were isolated by the state’s mountain ranges and allowed ecosystems to evolve separately over millions of years.

It’s why the watercress darter is found only in Black Warrior tributaries, and the Cahaba shiner doesn’t cross over into the Coosa.

“In terms of aquatic biodiversity, you have to go deep into the tropics to find places that have similar or more species of freshwater fishes and snails and mussels,” Duncan said. “So we wound up being stewards of a landscape that has tremendous biodiversity.”

What are the biggest threats?

Duncan listed three factors that are among the biggest threats to Alabama’s biodiversity: runoff, dams and climate change.

Since many of Alabama’s imperiled species are aquatic, runoff can have a huge impact. Water that used to naturally filter down through the ground after rainfall now runs across roofs and streets and parking lots into gushing torrents. The water carries pollution from roadways, pesticides, fertilizers, and sediment into these delicate aquatic ecosystems.

The water runs faster because it’s channeled into fast-moving streams and erodes more of the river banks with it. Crevices in between rocks that are a gold mine for salamanders like the Black Warrior waterdog, as well as other mussels, snails or fish get filled in with dirt.

Dams – ranging from massive hydroelectric projects to small culverts for roads – can segment fish populations and break up migration patterns for fish like the Alabama sturgeon. They can also transform free-flowing streams into controlled lakes, altering the natural systems that evolved in those places.

A warming climate will add more pressure to species that are already imperiled.

“Climate change kind of is like an it's like a force amplifier for all the existing problems that we have,” Duncan said. “We've always had flooding, and now it's getting worse. We've always had droughts. Now they're getting worse. We've always had high heat spells, and the problems those cause for our small tributaries that get overheated. And now those are getting worse.”

What can we do?

While Duncan said that personal responsibility choices like not littering and using less plastic are important, his primary recommendation is that people get involved in the policy decisions that impact Alabama’s wildlife.

“The thing that no one likes to spend time on is becoming aware of and engaged in policy,” Duncan said. “People need to know about the policies that are shaping their lives.

“It takes some education, and then people have to be motivated to engage with the folks that are shaping policy.”

In particular, Duncan cited Alabama’s lack of a dam inspection program, the absence of a state water plan, Alabama’s renewable energy policy and water conservation policies as areas where people could engage their representatives.

“I don't care what side of the issue they're on, the more people we get talking about policy, the better,” Duncan said.

Is it too late?

For some species, extinction is all but inevitable. But for the larger picture of biodiversity in the state, there’s still time to hold on to most of what we have now.

Jimmy Stiles, a wildlife biologist at Auburn University who has worked extensively with the eastern indigo snake and other endangered reptiles and amphibians in the state, said the Endangered Species Act has proved a valuable tool in preserving species.

“There are many species that are commonly encountered today that were once close to the edge,” Stiles said. “Creatures like alligators and Canadian geese are tremendous success stories.

“Hopefully, 50 years from now we will look back and say, ‘Wow, can you believe that flattened musk turtles used to be rare?’ Rather than saying, ‘You know there used to be these things call flattened musk turtles.’”

Why should we care?

Through this series, we’ve tried to introduce just a handful of the wide range of strange and endangered critters that share our state. We’ve also tried to list reasons why people might care.

It’s a topic near to Duncan’s heart. His book on Alabama biodiversity is aimed at general audiences, not scientists. He also teaches classes at BSC for non-science majors to try to inspire everyone to care about the wildlife that surrounds them.

He said people connect with species they may never have seen for a variety of reasons.

“Some people naturally connect with it,” Duncan said. “They care about the existence of other species. They like a diverse world, as opposed to a simple world, flat and boring, that doesn't have as much biodiversity.

“Some people come at it from a religious angle and say that we need to be stewards of creation, that all of this has been entrusted to us and we should be good caretakers.”

There are also selfish reasons to care about the tapestry of species that makes up our environment. Duncan says increasingly when he speaks to the public, he highlights the concept of “ecosystem services,” or things that natural ecosystems provide free of charge that would otherwise make it expensive or even impossible to continue with our way of life.

Wetlands filter pollutants out of the rainwater before it reaches our man-made treatment plants. Trees clean the air and replenish the oxygen we need to breathe. And those systems work better when they are naturally whole.

“Increasingly, studies have shown that ecosystems provide more services, and better-quality services, when their native species are present, and their populations are strong and healthy,” Duncan said. “So all these little critters out there in our streams and in our forests that are doing their daily business -- little things that most of us never see, the little weeds and bugs and mussels and snails of the world -- they, collectively, are making our ecosystems work.

“And when our ecosystems are working well, we as humans benefit from it.”

See the full series, Endangered in Alabama: