Government agencies and NGOs pour money into the management of waterways every year. The Ohio Department of Natural Resources (ODNR) alone has four ongoing watershed restoration projects, including Riparian Corridor Protection, Channel Restoration, Alternate Cattle Water Sources, and Dam Removal. While these projects are numerous, the results of restoration and management are often hard to immediately see. However, a new study led by Dr. Mark Pyron, a researcher at Ball State University, sheds light on how the management of the Ohio River Basin has led to benefits for fish populations.
The Ohio River Basin, shown below in Figure 1, has been altered dramatically by agricultural use and urban development over the last two centuries. Prior to the passage of the Clean Water Act in 1972, restrictions on what could be dumped into the waterway were few and far between. Pollution levels were high in the river basin and negatively impacted aquatic habitat for fishes. Today, the water quality in the Ohio River Basin is improving. Discharges into the Ohio River from direct sources, also known as point sources, are heavily regulated by agencies such as the EPA. The Ohio River Valley Sanitation Commission (ORSANCO) is another agency committed to improving the water quality and aquatic habitat in the Ohio River Basin. One way ORSANCO does this is through the long-term monitoring of fish populations in the river. Yearly monitoring allows scientists and management officials to see how conservation initiatives, like the Clean Water Act or ODNR restoration projects, are paying off for fish.
Using 57 years of fish population data from ORSANCO, Dr. Pyron and colleagues investigated how the composition of fish in the Ohio River Basin has changed over the last half century. Their study, entitled “Long-term fish assemblages of the Ohio River: Altered trophic and life history strategies with hydrologic alterations and land use modifications”, found that there have been significant changes in Ohio River fish populations over the last 50 years. More specifically, there has been an increase in the species richness, or number of species present, with year. In the study, 135 species of fish across 19 families were identified, with the most common species being the Gizzard Shad (Dorosoma cepedianum), Emerald Shiner (Notropis atherinoides), Freshwater Drum (Aplodinotus grunniens), Channel Shiner (Notropis wickliffi), Channel Catfish (Ictalurus punctatus), Threadfin Shad (Dorosoma petenense), Skipjack Herring (Alosa chrysochloris), Common Carp, Bluegill (Lepomis macrochirus), and White Bass (Morone chrysops) (Pyron et al 2019).
Researchers think that the increase in the number of fish species present in the Ohio River could be evidence that the management of the basin for improved water quality is working. As agriculture around the Ohio River Basin has decreased and forests have increased, runoff into the river has also decreased and led to less turbid, or clearer, waters. Less turbid water allows for better predation in fish that use vision to catch their prey, and forests increase the presence of insects, which are commonly consumed by fish. The availability of new resources allows more fish to be present in the river.
While results from the study have shown an overall increase in the number of fish species present, they have also shown that human alterations to the Ohio River waterway have impacted the types of fish species present. More piscivores, or fish that eat other fish, were found in the river each year. This could be due to the presence of dams that slow the flow of water and create lake-like conditions where piscivores normally thrive.
Overall, the study conducted by Dr. Pyron and his colleagues emphasizes that the management of the Ohio River Basin has been beneficial to fish conservation. However, as the climate continues to change and humans continue to impact waterways, it is necessary to conduct further investigations into how humans can influence fish populations and conserve their habitat into the future.
References:
- About Us. ORSANCO. Online. Retrieved September 24, 2019 from http://www.orsanco.org/
- Aquatic Stewardship. ODNR. Online. Retrieved September 24th, 2019 from http://wildlife.ohiodnr.gov/species-and-habitats/aquatic-stewardship
- Pyron, M., Mims, M. C., Minder, M. M., Shields, R. C., Chodkowski, N., and Arts, C. C. 2019. Long-term fish assemblages of the Ohio River: Altered trophic and life history strategies with hydrologic alterations and land use modifications. PLOS ONE 14(6):e0218915. Retrieved September 24, 2019 from https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0211848
- Summary of the Clean Water Act. EPA. Online. Retrieved September 24, 2019 from https://www.epa.gov/laws-regulations/summary-clean-water-act
- Van Velzer, R. 2019, May 7. Fish Diversity Making a Comeback in The Ohio River. WFPL. Online. Retrieved September 24, 2019 from https://wfpl.org/fish-diversity-making-a-comeback-in-the-ohio-river/