Meeting Abstract
High urbanization corresponds with an increase of impervious cover, and alters freshwater communities, which can lead to urban stream syndrome. In this study we focused on the effects of urbanization on the behavior of populations of Western Mosquitofish, Gambusia affinis, a generalist species with a world-wide distribution and often locally high abundance. We tested the hypothesis that fish from more urbanized streams, surrounded by higher levels of impervious cover will behave differently from fish from less urbanized streams. We collected female fish from four streams varying in levels of urbanization, determined by the percentage of impervious cover, agricultural development, and undeveloped land within a 2.2 km buffer radius of each site. The fish acclimated in the lab for a period of 42-48 hours, and then we placed individuals in a small enclosure holding tub with an opening to a larger tub. We recorded if the fish left the enclosure, individual boldness, and exploration duration in the large tub. We then put individuals into a group of four and recorded the shoaling behavior of a randomly selected focal individual, its relative distance to the center point of the other fish, and the duration they were within a 2 cm radius of the other fish. Urbanization level did not have a significant effect on the individual behavior of fish across populations; however, it did affect their shoaling behavior: fish from the rural sites shoaled closer together and stayed within 2 cm of each other for a longer duration. We suggest that fish found in higher levels of urbanization may be less social than those found in more rural streams.
