Class Project turned Publication – Investigating the Chicago River Reversal and its Impact on the Local Ecosystem
We got a class project published! The class was EAES 560, Extinctions: Modern and Ancient taught by Professor Roy Plotnick. Generally, extinction is a balance between living and dying. Everything is always dying (extinction rate, a sad fact of the world we live in). At the same time, new species are always being formed (speciation rate). A mass extinction occurs when the extinction rate is higher than the rate of speciation for an extended period of time; this has happened 5 times since the Ediacaran (beginning of multicellular life ~640 million years ago). All mass extinctions have external drivers. These drivers have varied from shifting continents to volcanism to maybe an asteroid one time. We are currently living in what some ecologists have termed “the 6th Extinction,” with the external drivers being anthropogenic.
Within this context, our class project was to look at species changes within Chicago and greater Cook County, IL over the last 100 years. The Chicago region was dominated by wetland ecospace prior to widespread settlement, so we determined the total wetland area and wetland fauna present in two distinct intervals: 1890-1910 and 1997-2017. We choose these intervals to capture changes that occurred after the 1900 reversal of the Chicago River. Everyone in our class was assigned a different task (e.g. determine the present bird populations via online databases, quantify map area using ArcGIS, etc). As a class we drove the direction of the paper and interpretation of the data with guidance and help from Roy. We collected most of the data online from museum records for free, and for fun we took a class field trip to the Chicago Academy of Sciences whose collections we sourced for the paper. The Chicago Academy of Sciences stores their non-displayed collections in a regular warehouse-style building next to the Metra tracks in Ravenswood. The building houses dusty cabinets with horned owls, poorly lit corridors with stuffed buffalo, drawers full of passenger pigeons, and smells like Indiana Jones’ closet, it was lovely.
Using the freely attained data, we determined that the Chicago wetlands have shifted from a swamp and marsh dominated landscape to a lake dominated landscape from historic to modern times. This makes total sense; we built our city on top of wetlands and the water has to go somewhere. Coincident with the changes in wetland area, mollusk and reptile species diversity have decreased, fish and bird species diversity have increased (not always a good thing), and amphibian and mammal species diversity have remained the same. Changes in species diversity are the result of extinctions, extirpations (a species lost from a specific region), species introductions, changes in wetland area, changes in wetland quality, and fragmentation of the existing wetland throughout the region. Although we can say that these are all regional drivers of change in species diversity through time, quantifying the drivers was outside the scope of the study and should guide future research.
This project illustrates the diversity of our department and field. As Earth Scientists, we get to consider the extirpation of a mollusk species from Humboldt Park (close to my house) within the context global change. We do this by working together as Biologists, Hydrologists, Geologists, Geochemists, Ecologists, and an ever-growing list of other “-ists,” to identify and solve problems in our collective field. As student -ists, we drove this project and we all worked together to author the publication. For me, as an organic geochemist who loves the Archean and Proterozoic (4 billion – 534 million years ago), I gained a huge appreciation for the park that floods in front of my house, the snails living in the puddles, and the -ists that study regional and global environmental change.
Read the full research article in Urban Ecosystems: Aquatic landscape change, extirpations, and introductions in the Chicago Region