To fear or to feed: the effects of turbidity on perception of risk by a marine fish

Abstract

Coral reefs are currently experiencing a number of worsening anthropogenic stressors, with nearshore reefs suffering from increasing sedimentation because of growing human populations and development in coastal regions. In habitats where vision and olfaction serve as the primary sources of information, reduced visual input from suspended sediment may lead to significant alterations in prey fish behaviour. Here, we test whether prey compensate for reduced visual information by increasing their antipredator responses to chemically mediated risk cues in turbid conditions. Experiments with the spiny damselfish, Acanthochromis polyacanthus, found that baseline activity levels were reduced by 23 per cent in high turbidity conditions relative to low turbidity conditions. Furthermore, risk cues elicited strong antipredator responses at all turbidity levels; the strongest antipredator responses were observed in high turbidity conditions, with fish reducing their foraging by almost 40 per cent, as compared with 17 per cent for fish in clear conditions. This provides unambiguous evidence of sensory compensation in a predation context for a tropical marine fish, and suggests that prey fish may be able to behaviourally offset some of the fitness reductions resulting from anthropogenic sedimentation of their habitats.

Developmental plasticity in vision and behavior may help guppies overcome increased turbidity

“…Our study is one of the first to show effects of development in turbid water on adult fish behavior (also see Gray et al 2012): although most previous studies document either no change (Ranåker et al 2012) or a decrease (Leahy et al 2011;Borner et al 2015) in baseline activity for adult fish Activity before and after the introduction of a predator cue to assay tanks for both treatments. Grey lines connect multiple trials for individuals.…”

“…Furthermore, previous studies have shown that fish placed in turbid water decrease activity (Leahy et al 2011;Borner et al 2015); thus, we predict that guppies reared in clear water and placed in turbid water will show decreases in activity, while fish reared in turbid water may be acclimated to turbid conditions (in part via transcriptional changes in their visual system) such that activity decrease in turbid water will not be observed. Here, we examine the integrated responses of the visual system and behavior to turbidity over a developmental timescale, demonstrating a multi-dimensional phenotypic response to rapid environmental change.…”

“…Previous studies have shown sensory compensation (a behavioral shift towards using information from one sense, e.g., olfaction) in predation contexts by fish when information from another sense (e.g., vision) is lacking (Hartman and Abrahams 2000; Heuschele et al 2009;Leahy et al 2011). Most studies purporting sensory compensation measure responses as behavioral shifts in reaction to multiple cue types of interest when organisms are placed in environments where information from one sense is eliminated or obscured.…”

Influence of predation risk on the sheltering behaviour of the coral-dwelling damselfish, Pomacentrus moluccensis

“…However, this relationship is further influenced by environmental factors such as water turbidity and topographic complexity (hereafter referred to as rugosity) (Beukers and Jones 1997;Rilov et al 2007; Leahy et al 2011). These factors may have complex effects on the predator's ability to detect prey and/or the level of risk perceived by the prey.…”

“…As reduced sheltering effectively decreases the benefits derived by host corals from mutualistic damselfishes, an indirect link between overfishing and coral health might exist (Garcia-Herrera et al 2017). Predator avoidance behaviours of site-attached fishes may vary in response to the environmental conditions prevailing on a reef, independently of predator abundance, and may be size-dependent (Leahy et al 2011;Helfman and Winkelman 2015). The size-spectrum theory predicts abundant small-bodied predators and few large-bodied ones (Sogard 1997).…”