A delicate balance exists at Illinois Caverns

WATERLOO (AP) – Deep inside the cave, there's no getting accustomed to the darkness.

It's just dark. No light. None.

And somehow, life continues to find a way to survive – even thrive – there.

At Illinois Caverns State Natural Area near Waterloo, not far from St. Louis, dozens of organisms call the cave home.

But adapting to what would seem to be an inhospitable environment for competitors isn't always a safe bet anymore.

That's because the delicate, low-energy cave environment easily can be upset by human behavior on the surface.

Illinois Caverns is in one of Illinois' karst regions, where water drains from the surface into sinkholes and into underground streams.

Water finds cracks in the limestone bedrock, and when it mixes with the carbon dioxide from the atmosphere, it creates a weak carbonic acid that dissolves a larger and larger path over time.

Water cuts and builds at the same time. Dissolved minerals are deposited and form many of the spectacular cave features.

Land around Waterloo is considered part of Illinois' sinkhole plain. Cave residents rely on debris from the surface washing into the cave and bringing the sun's energy along.

A trip through Illinois Caverns likely will turn up occasional piles of leaves or other organic debris from the surface that has washed in through a sinkhole.

"That is normal and healthy for a cave in moderation," says Steve Taylor, a biologist studying cave invertebrates at the Illinois Natural History Survey. "That is the stuff that was on the surface that captured the sun's energy, and when it died, it kept some of the energy when it fell into a sinkhole and washed into the cave."

Microorganisms such as fungi break down the surface debris, and then invertebrates such as isopods and amphipods feed on it. Salamanders may then feed on the isopods.

Conservation efforts to protect the fragile cave environment start with good environmental practices on the surface.

"The main point that I would emphasize is that anything that goes into the sinkhole also goes into the cave," Taylor says. "And that includes sewage, pesticides and anything thrown into the sinkhole.

"Because it's an open hole, its like dropping something into a storm sewer," Taylor says.

Leaking septic tanks, for example, can contribute extra nutrients to the cave system.

"One of the biggest problems is that these animals are adapted to a relatively low energy environment," Taylor says. "Lots of extra waste or plant material enriches the cave environment."

That's bad news for the animals that are restricted to the cave and its usual low-energy environment. Extra fuel means that some organisms adapted to living in or out of the cave now can move in to stay.

Then they compete with those that have no other option but to make a living in caves like Illinois Caverns.

The federally endangered Illinois cave amphipod is known from only a handful of caves.

"When you have lots of nutrients like sewage washed into the cave, the Illinois cave amphipod is less competitive relative to the other amphipod that you can find in springs on the surface," Taylor says.

Taylor says cave organisms are fascinating but rarely capture the public's imagination. He has recently started to study springtails, another cave invertebrate.

"Springtails have very little charisma," he says with a laugh. "It's the problem with working with invertebrates," he says. "They don't have the cute factor.

"But they represent the fabric of life, the diversity of life."