Chemical disturbance cues in aquatic systems: a review and prospectus

Abstract

In the natural environment, animals can face potentially dangerous and often regular exposure to major environmental fluctuations such as flash flooding and drought, or the approach of a predator. For many aquatic species, exposure to these ecological disturbances triggers the release of "disturbance cues"generally characterized as chemicals released when animals are startled but not injured. While the chemistry of such cues remains largely unexplored, they appear to provide early warning information to nearby individuals, potentially leading to behavioral decisions that increase overall fitness, particularly for social species that may coordinate group defense. In the literature, disturbance cues have received little attention relative to other chemical cues, such as damage-released alarm cues. However, recent advances in the study of disturbance cue communication have led an uptick in research on the subject. Here, we review the existing literature on responses to disturbance cues in aquatic systems. Although the majority of studies involve behavioral responses to a simulated predator approach, we describe various disturbance types across a broad range of taxa. We discuss the ecological implications of disturbance cues, including their role in risk assessment, signaling, learning, and species specificity. We also address several methodological challenges for this developing field of study, as well as the ethical and conservation implications of this research going forward. Future research on disturbance cues should address a number of key unknowns, including questions regarding disturbance cue chemistry, function, and generality.

Heat induces multi-omic and phenotypic stress propagation in zebrafish embryos

“…Heat stress responses at the molecular and behavioural levels are well studied in aquatic species, but its effect on chemical communication is less studied. Previous studies have focused mostly on cues released upon biotic factors such as injury (14) or disturbance (15). We have recently proposed that abiotic stress such as heat or low pH likewise elicits the release of olfactory cues, which we termed “stress metabolites” (16, 17).…”

“…Natural chemical communication is likely mediated by a cocktail of compounds (28). However, stress-induced chemical communication has previously been studied using mainly phenotypic and physiological endpoints (15). Consequently, the biological compound bouquets mediating specifically heat stress-related communication, and their molecular pathways of action, remain unknown.…”

Consequences of directly- and indirectly-experienced heat stress in a mutagenic environment

“…Biotically-stressed aquatic animals communicate with naive neighbours (Crane et al, 2022; Mathuru, 2016; v. Frisch, 1938).…”

“…While the effects observed in the social metabolite treatment could be ascribed to specific metabolites induced by heat, similar to what we reported previously ((Feugere et al 2021; Feugere et al 2023)) we cannot exclude that this bouquet of cues (Feugere et al 2023) also includes regularly excreted, non-heat-specific social cues. Ideally, cues from unstressed conspecifics should be included in future experiments as a better-suited control (Crane et al, 2022) to confirm the involvement and consequences of heat-induced vs. regular social metabolites in mutagenic environments.…”

Uncertainty about old information results in differential predator memory in tadpoles

“…in crustaceans [ 11 ]). There are two basic categories of social chemicals used in risk assessment; ‘alarm cues’ (AC) are released by injured conspecifics (generally during a predator attack), whereas ‘disturbance cues’ are characterized as chemical cues released by individuals that are disturbed but uninjured [ 12 , 13 ]. Both cues appear to be particularly widespread among aquatic species, perhaps due to the solvent properties of water or the limitation of visual information in some aquatic environments (e.g.…”