Effects of Predation Pressure On Suvival and Recruitment of Red Shiners

Red shiner is a common, widespread minnow native to streams of the central United States, and is highly invasive where it has been introduced. Despite being invasive, red shiners disappeared from native streams in southern Oklahoma where they were historically abundant. Over the period that red shiners declined (1985 to 2005), centrarchid predators increased in these streams, suggesting that predation pressure may have contributed to red shiner decline. Following a major flood in 2007, red shiners re-appeared in Brier Creek, but have failed to become re-established. Mesocosm experiments on factors inhibiting re-invasion of red shiners back into their native habitat suggested sunfish predation as a factor. To directly examine effects of predation pressure on survival and recruitment of red shiners, we conducted a mesocosm experiment in which we varied numbers and types of sunfish in an assemblage of species native to Brier Creek, including red shiners. Under no to low predation pressure, red shiners survived and reproduced. At moderate to high levels of predation, red shiners showed reduced survivorship and no recruitment.