Cranberry Lake Biological Station

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student research, biology, Adirondacks


At Cranberry Lake, one of the most commonly used topical products is insect repellant. Insect repellents are manufactured with varying percentages of DEET, or no DEET at all. DEET is a synthetic chemical consisting of organic compounds originally intended for jungle warfare. Trace amounts of DEET are found in local waterways throughout the summer, when swimming is a popular activity. This study focuses on Polyphemus pediculus, a zooplankton at the bottom of the aquatic food chain. Polyphemus pediculus is abundant in Cranberry Lake and is an indicator for health and functionality of the lake ecosystem. Three insect repellents containing varying percentages of DEET and two DEET-free repellents were tested on Polyphemus pediculus at high (6µL), medium (4µL), and low (2µL) amounts. The survivorship of zooplankton was observed over 30 minutes. It was found that insect repellants containing higher percentages of DEET killed Polyphemus faster than those containing lower percentages of DEET. It was also found that one DEET-free insect repellant killed the zooplankton at an equal rate, while the other killed them at a slower rate. Larger amounts of insect repellent in the water also killed Polyphemus faster. All insect repellents used in the experiment had adverse effects on survivorship on zooplankton, which should be taken into consideration before entering waterways. It can be concluded that insect repellant, even in trace amounts, can be detrimental to aquatic systems.


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