Chemical encoding of risk perception and predator detection among estuarine invertebrates

Abstract

An effective strategy for prey to survive in habitats rich in predators is to avoid being noticed. Thus, prey are under selection pressure to recognize predators and adjust their behavior, which can impact numerous community-wide interactions. Many animals in murky and turbulent aquatic environments rely on waterborne chemical cues. Previous research showed that the mud crab, , recognizes the predatory blue crab,, via a cue in blue crab urine. This cue is strongest if blue crabs recently preyed upon mud crabs. Subsequently, mud crabs suppress their foraging activity, reducing predation by blue crabs. Using NMR spectroscopy- and mass spectrometry-based metabolomics, chemical variation in urine from blue crabs fed different diets was related to prey behavior. We identified the urinary metabolites trigonelline and homarine as components of the cue that mud crabs use to detect blue crabs, with concentrations of each metabolite dependent on the blue crab's diet. At concentrations found naturally in blue crab urine, trigonelline and homarine, alone as well as in a mixture, alerted mud crabs to the presence of blue crabs, leading to decreased foraging by mud crabs. Risk perception by waterborne cues has been widely observed by ecologists, but the molecular nature of these cues has not been previously identified. Metabolomics provides an opportunity to study waterborne cues where other approaches have historically failed, advancing our understanding of the chemical nature of a wide range of ecological interactions.

Impacts of Global Warming and Elevated CO2 on Sensory Behavior in Predator-Prey Interactions: A Review and Synthesis

“…Chemical cues are prevalent in sensory-mediated predator-prey behaviors and may mediate detection of both prey (Weissburg et al, 2002) and predators (Kats and Dill, 1998) as these cues have the potential to persist over large distances (i.e., tens of meters) and long times (i.e., minutes) (Weissburg et al, 2014). Chemical cue production and emission is controlled by the sender; prey often determine predation risk from chemical waste products unavoidably released by predators Poulin et al, 2018) or by cues released by conspecific prey (e.g., alarm pheromones). The amount of cue produced can be an indicator of biomass and thus predator threat (Hill and Weissburg, 2013), and predator diet can change the identity of metabolites released by predators (Poulin et al, 2018) to chemically influence risk assessment by prey (Schoeppner and Relyea, 2005;Turner, 2008;.…”

Configural learning: a higher form of learning inLymnaea

“…Boiling alters the composition of the CE (e.g. metabolites in the urine; see Poulin et al, 2018) such that snails no longer respond to it with anti-predator behaviours (Orr et al, 2007). These snails were then trained as described above in hypoxic CO (Fig.…”

Phenotypic plasticity of senescence inDaphniaunder predation impact: no ageing acceleration when the perceived risk decreases with age

“…The chemical nature of predator cues perceived by prey is not known in most systems; yet, recent advances shed new light on both general principles and particular systems [74][75][76]. This is important as the nature of the cue and its predator specificity may present a constraint for recognition.…”