Midwest wetlands almost gone but still have most species

SPRINGFIELD, Ill. – Wetlands in the Midwest? It may be hard to believe but vast areas of today’s Corn Belt used to get so wet that malaria was common.

While the remaining wetlands are small and scattered, there’s still hope – new research shows that most of the original species may still survive.

Corn Belt. “We often look to other regions of the world as biodiversity hotspots but it is worth noting that some of the most heavily impacted regions – such as the Corn Belt – should not be written off as biodiversity wastelands,” said David Jenkins of the University of Illinois at Springfield.

In the mid-1800s, much of the Corn Belt – Iowa, Illinois, Indiana and Ohio – was tallgrass prairie that included extensive seasonal wetlands. For instance, ephemeral ponds used to cover about a fifth of Illinois (nearly 5 million acres) from roughly early spring to mid-summer.

By the mid-1900s, about 85 percent of these wetlands had been drained and converted to agriculture, which is similar to the rate of deforestation in tropical forests today.

The study. To assess the biodiversity of the Midwest’s remaining wetlands, Jenkins and his colleagues studied crustaceans in 13 ephemeral ponds near Bluff Springs, Ill.; the ponds were wide and shallow, 3 feet deep at most. They chose crustaceans because they are usually diverse and are important to these ecosystems.

The researchers sampled crustaceans from the ponds every week during the wet seasons of three years. Because there are no good records of the species that lived in Illinois’ wetlands historically, the researchers used their findings to extrapolate backwards and estimate how many crustacean species were there originally and how many have gone locally extinct.

These estimations were based on the fact that the number of species depends on how widely distributed they are. Jenkins and his colleagues found 33 crustacean species in the ponds they studied.

These included fairy shrimp, which are large (up to 1.5 inches), delicate and glide around on their backs; clam shrimp, which are dark brown, the size of a pencil eraser, and extremely active; and copepods, which are bright red and swarm in clouds below the surface of the water.

Conclusions. Extrapolating backward, the researchers estimate there were as many as 85 crustacean species in Illinois’ seasonal wetlands before they were drained. Similarly, the researchers estimate that 8-9 of the original crustacean species may have gone locally extinct.

Taken together, these findings suggest that 90 percent of the original crustacean diversity may still survive in the few remaining seasonal wetlands in Illinois. This means that despite the huge habitat losses, there could still be time to conserve most of the original species.

“Their existence will depend on our attention and action,” said Jenkins.