Trophic cascade in Lake Shel-oole, MT: a baseline study for high school environmental science students

Abstract

Teachers implement hands-on, inquiry-based learning into their classrooms because it is more effective for all types of learners both with comprehension and retention (Thuneberg et al., 2018). This is the method that I have adapted into my classroom. Shelby High School environmental students are in a unique situation that allows them to study an introduced species to an ecosystem study the long-term effects. In North Central Montana, there is a small lake named Shel-oole. Yellow perch were first sampled in Lake Shel-oole in 1994 and were able to flourish in this environment. In 2017, there was more than the average amount of precipitation and the population grew substantially. Yellow perch began to compete for food causing smaller fish size (for anglers), but fish size can also have a negative impact on the lake clarity from trophic cascade. Montana Fish, Wildlife and Parks devised a solution to decrease yellow perch numbers through the introduction of a top-level predator, the large mouth bass, and removal of 897 yellow perch. They do not have any data on the abiotic and biotic factors of the lake ecosystem other than fish sampling. The first goal of this study is to measure limnological data to determine if Lake Shel-oole is a suitable habitat to sustain a largemouth bass population. The second goal is to use this data to set up a baseline for a long-term research study question for students: Is Lake Shel-oole an environment where largemouth bass will be able to have a sustainable population and cause a trophic cascade? Limnological data were recorded in June and July of 2022, including dissolved oxygen levels, water clarity, pH levels, and temperature levels with equipment that students will use in future studies. Bathymetry data was recorded in June and July of 2022, using sonar and C-Maps to determine if this would be a viable site for largemouth bass. Dissolved oxygen levels ranged from 3.2 to 7.3 mg/L. Water clarity ranged from 66.5 cm to 77.5 cmfrom the surface. PH of Lake Shel-oole was approximately 8.0 and surface water temperature ranged from 18.0°C to 23.7°C. Bathymetry data indicated that the depth of Lake Shel-oole ranged from < 0.30 m to 4.3 m (6.7 m in years with more precipitation). Students will collect field samples using the same method. Six different classroom or field labs will take place to give them hands-on experience. Based on my results, it is likely that Lake Shel-oole is a suitable location for a sustainable largemouth bass population. However, this data acts as a baseline to for long term yearly data collection by local students to study and draw conclusions on the effects of introducing a new species into an ecosystem.