Lake Wells and the Lakeside Dining Commons
The ponds are a cultural landmark
The many lakes on campus have been a part of campus culture since the 1930s, when two lakes in front of the current library were established in honor of former University President Guy H. Wells and his wife Ruby. During that time, they have served our campus as landmarks for recreational fishing, lakeside dining, romantic outings , and even between-class nap locations. They are also important educationally and are utilized for courses such as Herpetology or Microbiology, and for hosting sustainability events such as the recycled boat regatta. These ponds also provide valuable ecosystem services as settlement ponds to remove material and contaminants from wastewater.
Three ponds in particular, the College of Education (COE) pond, Lake Wells, and Lake Ruby, have a combined drainage basin of 100 acres, representing more than 10% of the total area of the 900+ acre main campus. Thus, because of importance of these ponds to the campus community it is necessary to understand the impact of recent pond renovation on their biodiversity and function.
Draining the ponds in December 2017
A large brown bullhead (Ameiurus nebulosus) that was rescued from a draining pond
Beginning in December 2017, the COE pond, Lake Wells, and Lake Ruby were drained and dredged to remove accumulated settlement. Students and faculty have raised concerns about the animals that were in the ponds. We were among the Biology Department faculty and students that attempted to rescue some of these animals, but out observations suggested that there was near-complete eradication of vertebrate biodiversity in these three ponds. This is concerning due to the surprising biodiversity found on campus in recent surveys. For example, of the over 200 species of vertebrates that occur on campus, approximately 28% rely on campus wetlands and ponds almost exclusively, including at least 21 species of fish, 8 species of amphibians, 7 species of reptiles, 19 species of birds, and 3 species of mammals. Therefore, draining and dredging these three ponds is potentially a significant loss to campus biodiversity if these habitats do not recover to their previous states. While this result is concerning, draining and refilling these ponds also represents a unique opportunity to understand how biodiversity is established and maintained in these ponds, as well as the effects that our activities have on the wildlife present on our campus.
The cement well acting as an outflow in the College of Education Pond
Potential factors affecting recovery
Two primary concerns might affect how quickly these ponds recover: 1) the degree of connection to other local water bodies, and 2) the toxicity of the water given destruction of the natural biological filter. Past surveys indicate that connections to local, natural water bodies may be sufficient to maintain diversity over the long-term. However, these connections may include cement barriers (as shown above) that are difficult for fish and other aquatic vertebrates to traverse, and repopulation in the short-term may be constrained. An additional concern for repopulating these lakes is the need to restart the biological filtration process that can lead to toxic waste buildup upon being refilled. An established pond relies on microbial communities to convert toxic ammonia to non-toxic nitrates, making the water safe for its animal and plant inhabitants. Removal of the substrate will remove this biological filtration mechanism and require it to re-establish. Although this cycling is necessary for any new pond, these dredged ponds continue to receive waste runoff and decaying matter while in the process of re-establishing, potentially extending the duration of this process.
A pond slider (Trachemys scripta) basking
Evidence for recovery occurring
Since the ponds were refilled early Spring 2018, brief visual surveys have have identified the return of aquatic turtles, mosquitofish, breeding geese, foraging swallows, and even a nearby raccoon! These species represent those that may have been able to relocate or traverse shallow passages. Therefore, significant barriers to repopulation may be present in these ponds, but not impossible to overcome, and monitoring their recovery will be important for understanding these processes.