MERRILLVILLE — A recent study by Indiana State University shows environmental conditions in the Grand Calumet River basin are improving, due largely to dredging and less contamination in the upper parts of the East Branch.

Thomas Simon presented his findings Thursday from a study conducted in 2011 to the citizen advisory group, CARE.

The study measured the fish community and its biodiversity, developed an environmental index using amphibian species, and tracked diseases found in the blunt nosed minnow, a species found throughout North America. The study was funded through a $280,000 Great Lakes Restoration Initiative grant.

“Things are changing in the Greater Calumet,” Simon said. “It’s getting a lot better. The contaminants are being removed, and dredging is one of the reasons for the improvements to the aquatic life.”

A part of the study measured the biodiversity of the fish population, and showed that more native species were returning to the river. Small fish like sand shiners and banded killifish, a fish that has rarely been seen for 200 years in the Great Lakes basin, are starting to reappear in the river.

Simon added that the river still lacks predator fish, largely because the smaller prey haven’t re-established. Fish need aquatic plants for food and shelter.

“Grand Calumet was once a wetland area, with a very slow flowing river” he said. “With the dredging, we’ve pretty much made it into a clean slate. But these are good changes for the Calumet. The native species are returning.”

The study determined an amphibian index that will help identify whether there are stressors to the environment, like contaminants in the river or changes in the water levels.

“We had to establish indexes to help us measure the progress we’ve made in the river,” Simon said.

Also, the study measured the diseases and deformities, using over 1,200 samples of blunt nose minnows, determining the range of age in the population, if there were deformities and the ratios between male and female samples.

Simon used samples from a previous study in 1998 and noticed there were many more males than females, and most were dying before becoming 4 years old.

Samples from 2011 showed ratios closer to 1:1 for males to females, and there were fewer deformities.

One abnormal finding was no minnows were older than 1 year old. Simon hypothesizes that the young fish shows new populations moving from the Great Lakes into the river.

“All the fish looked really healthy,” he said. “We just don’t have enough age difference yet.”

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