Whole-lake influences of littoral structural complexity and prey body morphology on fish predator–prey interactions

Abstract –  We used a longline tethering method to examine the relationship between prey refugia, prey body morphology and the location and magnitude of predation mortality within an individual lake and among three lakes that differed in coarse woody habitat (CWH) and aquatic macrophyte abundances. Predation events were lowest in the macrophyte and/or CWH refuges, peaked at or just beyond the refuge edge and declined in pelagic portions of the lakes. Predation risk at the refuge edge and just beyond was positively correlated with the abundance of littoral refuge. In contrast, predation events within the refuge and in the pelagic zone were negatively correlated with littoral refuge abundance. Deep-bodied and spiny prey morphologies were less vulnerable to predation than fusiform prey lacking fin spines. The structural complexity of littoral zones and prey fish body morphology may influence the outcome of predator–prey interactions and ultimately determine fish species assemblages in lakes.