Climate Change Impacts on Eagle Marsh

The floating path at Eagle Marsh lays on the ground July 18 because the water basin it once floated on is dry. With climate change causing more hot weather in summers and less frequent rains, the marsh could experience similar drying in the years ahead. (Kevin Kilbane)

For years, young children could slip on a pair of boots in the Eagle Marsh barn, grab a dip net, maybe endure a misting of bug spray and then tromp over to the shallow-water basin across from the barn. Young scientists then could dip their nets into the water to see what little creatures they scooped up.

Installation of a floating walkway gave them a chance to get farther out to slightly deeper water.

This summer, however, the floating walkway lays beached, surrounded by fresh grass and some cattails. Benches stand where water once crept up to the gravel drive. In mid-July, a small depression toward the trees held a puddle, the last bit of water in the basin.

Extremely hot, dry weather this summer and last summer have dried down Eagle Marsh. It’s a foreshadowing of what the marsh may endure in the future as climate change impacts northeast Indiana.

The good news: The filling and drying down of the marsh could actually increase habitat and attract an even greater diversity of plants and animals to Little River Wetlands Project’s 831-acre property.

The bad news: If the drying out persists over long periods of time, upland plants can move in and take over the land.

Climate change impacts

The weather we’ve had this year looks like a preview for what we can expect from climate change in the decades ahead.

Indiana will experience warmer winters with more rain and less snow, Purdue University’s Institute for a Sustainable Future reported in “Indiana’s Past & Future Climate: A Report from the Indiana Climate Change Impacts Assessment.” The report, which was published in spring 2018, is the institute’s most recent assessment report on the topic.

Summers will be hotter, with potentially 10 to 15 more days over 95 degrees by year 2050 in northern Indiana than the 10 or so days we experience now, the report said. That total could jump by year 2080 to about 20 to 50 more days above 95 degrees annually than what we endure today.

Indiana likely will receive 6% to 8% more precipitation yearly by 2050 than it receives today, the Purdue institute said in a spring 2023 report, “The Future of Indiana’s Water Resources: A Report from the Indiana Climate Change Impacts Assessment.” However, much of the increase will come in winter and spring, potentially increasing the risk of flooding. Summer and fall likely will be dryer than in the past, with rain falling in less-frequent but more-intense storms, the report said.

By 2050 and later, Indiana may lose an additional 6% to 7% of its water annually through evapotranspiration, raising the statewide average to about 36 inches of water lost per year, the report said. Evapotranspiration includes water lost from use by plants and through evaporation from surface-water bodies and soil.

The risk of droughts will remain about the same as now, the report said. However, we could experience more sudden, limited-time droughts, especially in late summer and fall.

The drying likely will reduce habitat quality and connectivity, the institute reported in “Aquatic Ecosystems in a Shifting Indiana Climate: A Report from the Indiana Climate Change Impacts Assessment,” which was released in fall 2018. Frogs and salamanders probably will have less success in breeding, the report noted.

Local perspective

Other factors also could play a role in the water levels in Eagle Marsh.

If a nearby quarry pumps water out of its location as part of its operations, it could result in the water table dropping in the surrounding area, including Eagle Marsh, said Bruce Kingsbury, professor of biological sciences at Purdue University Fort Wayne and director of the university’s Environmental Resources Center.

Kingsbury has been studying wetlands and their wildlife for more than 30 years. He and his students have done extensive research on a variety of animals, including wetland snakes, turtles, amphibians, mammals and birds. He also has provided guidance on wetland management and restoration to agencies and organizations.

The water table describes where the water is located in an area.

“When you have open water, the water table is above the soil,” Kingsbury explained. “If you don’t have open water, then that means the water table is subterranean, and it could be right at the surface or it could be very far down.”

Kingsbury said there are many types of wetlands. He describes Eagle Marsh as a semi-permanent wetland.

“They might stay full for years,” he said, “but then they could also dry down, unlike a lake, which always has water in it.”

He expects climate change, with its less frequent but heavy rainfalls, will make wetlands more “flashy.” Water levels probably will go up and down more frequently, and the fill-ups could happen quickly.

Kingsbury said the changing water levels could be a good thing: Ephemeral wetlands, which tend to fill in the spring and dry up in the summer, contribute more to biodiversity than permanent wetlands. The variability of the water depth along the shore drives diversity. The center portion of wetland ponds typically don’t support much life.

Areas that hold water year-round tend to have fish in them, he said. Fish eat the eggs and larva of other wetland species, such as frogs and salamanders. If the water in the wetland dries down by mid-summer, however, fish can’t survive, he said. Species such as frogs, fairy shrimp and others will have completed their life cycles and don’t need standing water.

The water in shallow, ephemeral wetlands also warms up faster in the spring than water in larger, deeper bodies of water, the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) reported in 2008 in the publication “Biological Technical Note #7.” The warmer water encourages growth of important wetland food sources such as snails, worms, fairy shrimp, midge larvae and other invertebrates.

Water levels also control plant diversity in a wetland.

“The more time the wetland is dry, the more opportunity upland plants have to invade,” Kingsbury said. “If it fills back up again, then it will kill those plants because they’re not tolerant at all to what I call ‘wet feet.’

“In general, if an area is covered with water for more than a few months, upland plants will not survive,” he said. “The most important time for this is spring, when plants are coming out of winter dormancy and investing in new growth. If water covers that long (enough) or often enough, the plant dies. Many plants will also die if their roots are wet for too long.”

The drying down of wetlands also offers another potential benefit, he noted. If a wetland is mostly dry when heavy rains fall, it can hold more water during flooding.

Planning for the future

“One of the things that my research and that of others has shown is that landscapes that have a variety of kinds of wetlands have the greatest biodiversity,” Kingsbury said.

Little River Wetlands Project could enhance habitat effectiveness at Eagle Marsh by striving for diversity in hydrology, he said. Some areas should hold water all year, so they can be a refuge for wetland species in extremely dry years. Other areas should hold water for an intermediate time period. Still other areas should hold water for a short time.

“What we are striving for is what has been called macrotopography, which is gentle undulations in the ground that promote a variety of depths of water,” he explained.

Macrotopography features include swales, oxbows, potholes, basins, mounds and ridges, the NRCS said in its technical note.

Looking ahead, does Kingsbury think climate change will improve Eagle Marsh?

“I don’t,” he said. “But I actually feel that if the wetlands in Eagle Marsh are more ephemeral, they will lead to higher biodiversity.”