PREDATION RISK INFLUENCES REPRODUCTIVE-BEHAVIOR OF IOWA DARTERS, ETHEOSTOMA EXILE (OSTEICHTHYES, PERCIDAE)

In this study we tested the effects of predation risk on reproductive behaviour of Iowa darters (Etheostoma exile). We recorded the frequenc y of courtship behaviour (head shaking) and spawning acts for 30 min b efore and after removing an opaque barrier to expose groups of darters to (1) an empty tank (the before-pike treatment), then (2) a tank con taining a pike (the pike treatment), and finally (3) an empty tank (th e after-pike treatment). In response to the pike, darters performed si gnificantly less reproductive behaviour than before exposure to the pi ke. Furthermore, darters performed proportionally less reproductive be haviour in the area in the immediate vicinity of the pike where risk o f predation was highest. However, darters continued to occupy the risk y area while exposed to the pike. Removal of the barrier in the absenc e of the pike (the before- and after-pike treatments) had no effect on the overall level of reproductive behaviour, the proportion of reprod uctive behaviour performed in the; immediate vicinity of the pike tank (the risky area), or use of the risky area.