FRANCES GELWICK, Texas A&M University, College Station, Texas 77843-2258, USA

BILL MATTHEWS, University of Oklahoma Biological Station, Kingston, Oklahoma 73049, USA

JEFF STEWART, University of New Orleans, New Orleans, Louisiana, USA

HANK RAY, University of Oklahoma Biological Station, KIngston, Oklahoma 73049, USA

Red shiners have not successfully established in upland streams, where cooler water prevails, and communities are dominated by a complex group of other smaller fishes, many endemic. If streams warm 3-5°C, the movement of red shiners into these streams may occur. Introduction of red shiners has had devastating effects on native fishes in other areas. We test the effects of red shiners and warming on a suite of four native upland fishes, selected for different phylogenetic and ecological predictors of competition with red shiners. Experimental streams (3 pools, 2 riffles each) were constructed to model these communities. Behavioral interactions, and habitat use were recorded in experiments replicated in four seasons and three years. Final numbers of adult survivors, larval and juvenile production were determined. Aggression rates among other species were lower when red shiners were present, and increased at higher temperatures. Highest aggressivity was due to red shiners in summer during reproductive activities. Some species shifted mesohabitat use in the presence of red shiners by using different stream pools. Cooler temperatures delayed reproductive activity by female more than male red shiners, which spawned with other species. Initial samples indicate higher larval production at ambient upland temperatures, than warmed streams, and in streams with red shiners. However, specific identification of larval fishes is in progress.