Predator identity and consumer behavior: differential effects of fish and crayfish on the habitat use of a freshwater snail

Abstract

Predators can alter the outcome of ecological interactions among other members of the food web through their effects on prey behavior. While it is well known that animals often alter their behavior with the imposition of predation risk, we know less about how other features of predators may affect prey behavior. For example, relatively few studies have addressed the effects of predator identity on prey behavior, but such knowledge is crucial to understanding food web interactions. This study contrasts the behavioral responses of the freshwater snail Physellagyrina to fish and crayfish predators. Snails were placed in experimental mesocosms containing caged fish and crayfish, so the only communication between experimental snails and their predators was via non-visual cues. The caged fish and crayfish were fed an equal number of snails, thereby simulating equal prey mortality rates. In the presence of fish, the experimental snails moved under cover, which confers safety from fish predators. However, in the presence of crayfish, snails avoided benthic cover and moved to the water surface. Thus, two species of predators, exerting the same level of mortality on prey, induced very different behavioral responses. We predict that these contrasting behavioral responses to predation risk have important consequences for the interactions between snails and their periphyton resources.

Diel activity cycles of freshwater gastropods under natural light: Patterns and ecological implications

“…In general, active diurnal species may be more alert against diurnal predators and more vulnerable to nocturnal predators. Such a hypothesis is consistent with the predominantly behavioral antipredator defenses displayed by the most active, but structurally vulnerable, pulmonates tested in this study (P. acuta and P. planorbis) (e.g., Turner et al, 1999;but see DeWitt et al, 2000). B. leachii instead may resort to behavioral responses when active (e.g., by quickly retreating into the shell and shutting the operculum: Bro¨nmark and Malmqvist, 1986) and to structural defenses when inactive (i.e., thick shell with operculum closed shut).…”

“…Based on qualitative observations in the 1-L "leftover" container and in culturing aquaria, the low degree of oviposition of G. truncatula and V. piscinalis (Table 3) appeared to be associated with seasonal reproductive cycles. Absence of jerky movements by active snails, rare long-term wandering above the water line by pulmonates, and rare complete withdrawals into shells also indicate minimal or absent stress (Turner et al, 1999;Hourdin et al, 2006; Ms. Sarah Rid, University of Konstanz, personal communication). Short-term crawling just above the water level, with snails voluntarily reentering the jar water by the next observation round, appeared to be most often post-feeding moments of rest, and was not interpreted as a response to stress.…”

“…2), exhibited by the otherwise structurally vulnerable P. acuta supports the hypothesis that this species strongly relies on behavioral antipredator defenses that require a certain degree of constant alertedness (e.g., crawling out of water, detaching from substratum, etc. : Turner et al, 1999). However, studies specifically targeting a link between activity and antipredator defense are needed to test this hypothesis.…”

The long-term effects of invasive signal crayfish (Pacifastacus leniusculus) on instream macroinvertebrate communities

“…Some life history characteristics may reduce predation effects and, as a consequence of their high predation risk, many gastropod species display avoidance behaviour by migrating above the waterline for several hours (Alexander and Covich, 1991;Crowl and Covich, 1990;Turner et al, 1999), whilst others demonstrate changes to their life history through enhanced growth rates and lowered reproduction rates (Hoverman et al, 2005). Under experimental conditions P.…”

Interactive effects of predation risk and parasitism on the circadian rhythm of foraging activity in the great pond snailLymnaea stagnalis(Gastropoda: Lymnaeidae)

“…Generally, snails try to minimize their predation risk by populating habitats that provide a refuge from the predators (Alexander and Covich, 1991a;Turner, 1996) and by being less active during times when the predation risk is high (Sih and McCarthy, 2002). The type and degree of the avoidance response by snails depend on the type of the predator (Turner et al, 1999), the strength of the cues from the predator (stronger cues eliciting greater responses: McCarthy and Fisher, 2000;Keppel and Scrosati, 2004) and snail body size (Alexander and Covich, 1991b).…”