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Recording Dissolved Oxygen Levels at Spawning Site of Invasive Trout Species

Case Study Description

The introduction of non-native fish species in lakes has led to the disruption of aquatic ecosystems and the decline or elimination of native species of fish. Yellowstone Lake in Wyoming is suffering from the invasion of Lake Trout (Salvelinus namaycush) which has caused a steep decline in the population and health of the native Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri). A project, funded in part by the U.S. National Parks Service, was launched with the goal of killing Lake Trout embryos and restoring the natural ecosystem in Yellowstone Lake.

MiniDOT Loggers Deployed at Carrington Island

Carrington Island is a prominent spawning site for Lake Trout in Yellowstone Lake. The project leaders deployed 32 miniDOT Loggers at Carrington Island for the purpose of measuring the changes in Dissolved Oxygen (DO) levels once they released the carcass analoge pellets.

The carcass analoge pellets are soy and wheat based pellets designed to recreate the same nutrients as dumping Lake Trout carcasses in the lake would. The goal of the project was to drop the DO levels to around 3.5 mg/L for 50 hours. These conditions have previously been successful at creating a 100% mortality rate for Lake Trout embryos ~20cm in substrate.

Data Collection

DO levels and water temperatures were recorded with the miniDOT Loggers at a 60-minute sampling interval. The loggers were placed at substrate depths of 0cm and 20cm. 24 of the 32 miniDOT Loggers were collected from the spawning site in October 2019 for the researchers to pull data. Due to constraints in substrate types, the researchers were only able to measure DO at the surface of the lake. The data pulled from the 24 loggers that were removed from the 0cm substrate depths at the end of October is promising, but the researchers are hoping to learn more and have more concrete conclusions from the data to be collected from the remaining 8 loggers.

Product Description

The miniDOT® Logger is a completely submersible instrument that logs dissolved oxygen and temperature measurements. The oxygen sensor is an optode that measures dissolved oxygen concentration in water through a fluorescence method. Data are recorded to an internal SD card. Operation of the miniDOT Logger such as setting the time and sample interval can be accomplished via the USB cable.