The Relationship between Turbidity and Carotenoid-based Coloration of Centrarchid Fishes in Urban Streams

Tiffany Atkinson will present her honors presentation on Monday (4/11) from 9 AM in 245 Kottman Hall. Her presentation is The Relationship between Turbidity and Carotenoid-based Coloration of Centrarchid Fishes in Urban Streams.
Faculty Advisor:  Suzanne Gray

Description of research: Agricultural and urbanization practices cause runoff of nutrients and sediments into aquatic systems, leading to heightened levels of turbidity (i.e. amount of suspended particles in the water) and loss of aquatic biodiversity. Increased turbidity can alter visual environments through the differential scattering and absorption of light underwater. Therefore, in fishes that use visual cues to find mates, the effectiveness of visual signals can be compromised by turbidity and interfere with mating systems such that hybridization can occur. Carotenoid pigments responsible for red and yellow color patterns are energetically costly for fish to acquire from their diet. If signals are interrupted by increased turbidity, then the cost of obtaining and displaying carotenoid-based colors may not be profitable. Centrarchidae is a family of fish that use carotenoid-based visual cues to help attract mates. Here, I tested for a relationship between increased t  urbidity and carotenoid-based coloration in several centrarchid fishes from degraded urban streams. I collected >200 fish from low and high turbidity sites on each of the Olentangy (n=2) and Scioto Rivers (n=2) during spring, summer and fall 2015. Total body red and yellow coloration was evaluated using a standard photographic technique for Bluegill (Lepomis macrochirus), Green Sunfish (Lepomis cyanellus) and their hybrids. There was a positive relationship between standard length and red-yellow coloration across all three groups. However, I found a strong negative relationship between turbidity and red-yellow color expression in Bluegill. Bluegill are used as an indicator of good water quality, and these results indicate their coloration is affected by turbid systems which could lead to increased hybridization.