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Bluegills:Healthy Habitats

by Jennifer Miller

Pages 2 and 3 of 10

Bluegill Sunfish: Healthy Habitats
Bluegills are primarily freshwater fish. They are found in warm, quiet water – ponds, lakes, and slow moving streams and rivers
Bluegills are also common in all the tributaries of the Chesapeake Bay, and are tolerant of brackish water with moderate salt levels.
Several environmental factors contribute to a healthy habitat for any aquatic organism. Changes in water temperature can affect aquatic life. Bluegills prefer a temperature range between 65-80°Fahrenheit (F), but they can tolerate a much wider range.
Unlike humans, fish use gills to get oxygen from the water. Bluegills prefer DO level of at least 5 mg/L although they can tolerate as low as 1 mg/L for very short periods.
Too many nutrients are the main cause of the Bay’s poor health. Almost all people and industries in the
watershed send nutrients into the Bay and its tributaries. Nitrogen and phosphorous are the two nutrients of concern. These nutrients reach the Bay from three sources: wastewater treatment plants; urban, suburban and agricultural runoff; and air pollution. Nutrients can also come from natural sources, like soil, plant material and wild animal waste.
Scientists can monitor the nutrient level by investigating the water chemistry through nitrate, nitrite, and ammonia tests. These three tests help determine if the nitrogen levels are optimal for a healthy habitat. There should be less than 40 ppm of nitrates, and 0 nitrites and ammonia present in a bluegill habitat.
Another way scientists investigate water chemistry is by observing pH levels of water. A bluegill needs its water’s pH level to be between 6.5-8.5 in order
to survive.3