Disturbance cues in freshwater prey fishes: Does urea function as an ‘early warning cue’ in juvenile convict cichlids and rainbow trout?

Abstract

Freshwater vertebrate and invertebrate prey species commonly rely on chemosensory information, including non-injury released disturbance cues, to assess local predation threats. We conducted laboratory studies to (1) determine if urea can function as a disturbance cue in juvenile convict cichlids and rainbow trout and (2) determine if the background level of urea influences the behavioral response to a subsequent pulse of urea (‘background noise’ hypothesis). In the first series of trials, juvenile cichlids and trout were exposed to urea at varying concentrations (0 to 0.5 mg L-1 for cichlids and 0 to 1.0 mg L-1 for trout). Our results suggest that both cichilds and trout exhibited functionally similar responses to urea and conspecific disturbance cues and that increasing the concentration of urea results in an increase intensity of antipredator behaviour. In the second series of trials, we pre-exposed cichlids or trout to intermediate or high concentrations of urea (or a distilled water control) and then tested for the response to a second pulse of urea at at intermediate or high concentrations (versus a distilled water control). Our results demonstrate that pre-exposure to urea reduces or eliminates the response to a second pulse of urea, supporting the background noise hypothesis. Together, our results suggest that pulses of urea, released by disturbed or stressed individuals, may function as an early warning signal in freshwater prey species [Current Zoology 58 (2): 250–259 , 2012].

Does donor group size matter? The response of guppies (Poecilia reticulata) and convict cichlids (Amatitlania nigrofasciata) to disturbance cues from conspecific and heterospecific donors

“…After passing the model through the tank, we waited 60 s and softly mixed the water around the tank and removed 125 mL of tank water to be used as a disturbance cue. This procedure has previously been used to successfully collect disturbance cues (Vavrek and Brown 2009;Brown et al 2012). We collected all cues immediately before the experiment and used them within an hour of collection.…”

“…Alarm cues are reliable and honest indicators of risk (Chivers et al 2012) and can elicit dramatic short-term increases in predator avoidance behaviour (Ferrari et al 2010;Brown et al 2011;Chivers et al 2012). Disturbance cues are argued to be metabolic by-products, released in the urine or across the gill epithelium (Kiesecker et al 1999;Vavrek et al 2008;Brown et al 2012) by aquatic vertebrates when stressed or disturbed (Wisenden et al 1995;Kiesecker et al 1999;Abreu et al 2016). When detected by nearby conspecific and heterospecific prey, disturbance cues may function as an "earlywarning" cue of nearby predation threats (Wisenden et al 1995;Kiesecker et al 1999).…”

A novel alarm signal in aquatic prey: Familiar minnows coordinate group defences against predators through chemical disturbance cues

“…In fish, urine pulses are used to release mating pheromones (Sorensen & Stacey, ; Stacey, Chojnacki, Narayanan, Cole, & Murphy, ), advertise dominance (Almeida et al., ; Bayani, Taborsky, & Frommen, ; Maruska & Fernald, ), differentiate kin (Moore, Ives, & Kell, ) and, presumably, familiar individuals as well (Ward, ). Disturbance cues in fishes likely involve urea (Brown, Jackson, Malka, Jacques, & Couturier, ), as supported by the fact that fish perceive the presence and intensity of heterospecific disturbance cues, but not the number of individuals (Goldman, Singh, Demers, Feyten, & Brown, ; Vavrek & Brown, ).…”

Perch, Perca fluviatilis show a directional preference for, but do not increase attacks toward, prey in response to water-borne cortisol

“…In aquatic systems chemical cues are a principal source of information ( DeBose & Nevitt, 2008 ; Ferrari, Wisenden & Chivers, 2010 ). Prey increase anti-predator behaviors in response to the chemical cues of predators (e.g., kairomones Ferrari, Wisenden & Chivers, 2010 ), as well as the chemical cues released by prey that have been injured by predators (e.g., damage-released alarm cues, Mathis, Chivers & Smith, 1993 ; Harvey & Brown, 2004 ; Chivers, Brown & Ferrari, 2012 ; Lönnstedt, McCormick & Chivers, 2012 ), and by prey that have been disturbed or stressed by predators, without being injured or consumed (e.g., disturbance cues, Chivers, Brown & Smith, 1996 ; Vavrek et al, 2008 ; Vavrek & Brown, 2009 ; Ferrari, Wisenden & Chivers, 2010 ; Brown et al, 2012 ). By responding to the chemical cues of heterospecifics and conspecifics, about the presence of predators, prey have increased chances of survival during encounters with predators ( Mirza & Chivers, 2002 ).…”

“…Disturbance cues exist in a variety of systems, including invertebrates, amphibians, and freshwater fish ( Hazlett, 1990 ; Wisenden, Chivers & Smith, 1995 ; Kiesecker et al, 1999 ; Bryer, Mirza & Chivers, 2001 ; Mirza & Chivers, 2002 ; Jordão, 2004 ; Brown et al, 2012 ). It has been suggested that nitrogenous compounds in urine, and respiratory byproducts could act as disturbance cues ( Hazlett, 1990 ; Kiesecker et al, 1999 ; Vavrek & Brown, 2009 ; Brown et al, 2012 ). One potential disturbance cue that has received less research attention is the stress hormone cortisol ( Olivotto et al, 2002 ; Vavrek & Brown, 2009 ), the principal glucocorticoid in teleost fish ( Brown, Gardner & Braithwaite, 2005 ).…”