Application of Microsatellite Analysis to Identify Barriers to Warmwater Fish Movements in Headwater Streams

Assessing the severity of potential barriers to fish movements in headwater streams continues to be a challenging goal. In addition to migration for reproduction, connectivity among habitats can influence extinction and recolonization dynamics as well as source-sink dynamics of metapopulations.  This study was designed to characterize the genetic structure of two common warm-water species within five Ouachita Mountain streams (longear sunfish, Lepomis megalotis, and highland stoneroller, Campostoma spadiceium). Microsatellite analysis of seven stoneroller primers and ten longear primers revealed multiple longear and stoneroller populations within the stream networks. The recognizably distinct populations coincided with the presence of barriers such as waterfalls, culverts and areas of seasonal dryness.  In an extreme case, we detected three separate populations of longear sunfish within 4 km of each other in one stream. In total ten longer sunfish and seven stoneroller populations were found in five streams less than 11 km long. Such results highlight the sensitivity of microsatellite analysis and its potential as a tool in studies of fish movement in headwater streams.