Nonconsumptive Effects of Predation and Impaired Chemosensory Risk Assessment on an Aquatic Prey Species

Abstract

Weak levels of acidity impair chemosensory risk assessment by aquatic species which may result in increased predator mortalities in the absence of compensatory avoidance mechanisms. Using replicate populations of wild juvenile Atlantic salmon (Salmo salar) in neutral and acidic streams, we conducted a series of observational studies and experiments to identify differences in behaviours that may compensate for the loss of chemosensory information on predation risk. Comparing the behavioural strategies of fish between neutral and acidic streams may elucidate the influence of environmental degradation on nonconsumptive effects (NCEs) of predation. Salmon in acidic streams are more active during the day than their counterparts in neutral streams, and are more likely to avoid occupying territories offering fewer physical refugia from predators. Captive cross-population transplant experiments indicate that at equal densities, salmon in acidic streams do not demonstrate relative decreases in growth rate as a result of their different behavioural strategies. Instead, altering diel activity patterns to maximize visual information use and occupying relatively safer territories appear sufficient to offset increased predation risk in acidic streams. Additional strategies such as elevated foraging rates during active periods or adopting riskier foraging tactics are necessary to account for the observed similarities in growth rates.

Rapid plastic changes in brain morphology in response to acute changes in predation pressure in juvenile Atlantic salmon (Salmo salar) and northern redbelly dace (Phoxinus eos)

“…Additionally, cessation of the supplemental feeding upon leaving the hatchery required the fry to feed on and potentially compete for drift fodder (Imre et al 2005). Beyond the stresses of the transition, the HR fry may have been subject to non-consumptive effects of predation (NCEs), such as reduced foraging time and elevated stress (Elvidge et al 2014;Elvidge and Brown 2015). We expected the HR fry to exhibit signs of these NCEs with potentially reduced standard length, mass, condition index, and (or) total brain size.…”

Uncertainty about predation risk: a conceptual review

“…For example, turbidity in aquatic systems may also lead to incomplete visual cues (Michael, Patman & Lutnesky, 2021; Chivers et al ., 2013). Similar environmental background ‘noise’ can also mask both sounds and odours (Elvidge & Brown, 2015 a ; Chan et al ., 2010). Hence, the signal‐to‐noise ratio within each sensory modality is a key determinant of the information acquired from a cue (Dall, 2010; Battaglia, 2008).…”

The role of sensory modalities in producing nonconsumptive effects for a crayfish–bass predator–prey system

“…In most literature, the alteration of prey behavior is placed under non-consumptive effects. The behavioral (or physiological and morphological) responses to these sensory landscapes can dictate ecological interactions like social behavior, size and location of foraging areas, and even territory sizes D r a f t (Davenport and Chalcraft 2013;Elvidge and Brown 2015;Larsen 2012). Once an increased predatory threat (detected through multiple modalities) is detected most species show a reduction in foraging and mating behaviors and resort to predator avoidance behaviors, such as seeking shelter, fleeing, and/or displaying a defensive stance (Smith and Belk 2001).…”

“…Examples of consumptive effects include Helicoverpa armigera (Hübner, 1808) larvae feeding on Australian cotton crops (Rendon et al 2015) to a lion attacking and consuming a gazelle. Non-consumptive effects (NCEs) are defined as the indirect interactions between predators and prey (Davenport and Chalcraft 2013;Elvidge and Brown 2015;Weissburg et al 2014). These indirect interactions refer to the factors of intimidation prey demonstrate while in areas of previous and potential predatory threats.…”

“…From such concepts, arose the "landscape of fear" theory (Laundré et al 2010). Several studies have shown that prey alter their use of the landscape according to a perceived threat of predation (Elvidge and Brown 2015;Fine et al 2011;Laundré et al 2010;Weissburg et al 2014). Laundré et al (2010) demonstrated how mule deer (Odocoileus hemionus) alter their use of a landscape according to predation risk of pumas (Puma concolor L.).…”