Cadmium disrupts behavioural and physiological responses to alarm substance in juvenile rainbow trout (Oncorhynchus mykiss)

Abstract

SUMMARY Alarm substance is a chemical signal released from fish skin epithelial cells after a predator causes skin damage. When other prey fish detect alarm substance by olfaction, they perform stereotypical predator-avoidance behaviours to decrease predation risk. The objective of this study was to explore the effect of sublethal cadmium (Cd) exposure on the behavioural and physiological responses of juvenile rainbow trout (Oncorhynchus mykiss) to alarm substance. Waterborne exposure to 2 μg Cd l–1 for 7 days eliminated normal antipredator behaviours exhibited in response to alarm substance, whereas exposures of shorter duration or lower concentration had no effect on normal behaviour. Furthermore, dietary exposure to 3 μg Cd g–1 in the food for 7 days, which produced the same whole-body Cd accumulation as waterborne exposure to 2 μg l–1, did not alter normal behaviour,indicating that an effect specific to waterborne exposure alone (i.e. Cd accumulation in the olfactory system) results in behavioural alteration. Whole-body phosphor screen autoradiography of fish exposed to 109Cd demonstrated that Cd deposition in the olfactory system (rosette, nerve and bulb) during waterborne exposure was greater than in all other organs of accumulation except the gill. However, Cd could not be detected in the brain. A short-term elevation in plasma cortisol occurred in response to alarm substance under control conditions. Cd exposures of 2 μg l–1 waterborne and 3 μg g–1 dietary for 7 days both inhibited this plasma cortisol elevation but did not alter baseline cortisol levels. Our results suggest that exposure to waterborne Cd at environmentally realistic levels (2 μg l–1) can disrupt the normal behavioural and physiological responses of fish to alarm substance and can thereby alter predator-avoidance strategies, with potential impacts on aquatic fish communities.

Effects of Cu on plasma cortisol and cortisol secretion by adrenocortical cells of rainbow trout (Oncorhynchus mykiss)

“…Exposure to metals and other toxicants that impair cortisol secretion could then influence social interactions and cortisol-dependant processes. Scott et al (2003) reported that plasma cortisol levels in rainbow trout increased when fish were exposed to an alarm substance, a chemical released from skin epithelium, and this increase was inhibited by Cd. Other studies provided evidence that the capacity to raise plasma cortisol is impaired in fish exposed to organic pollutants (Aluru et al, 2004) and metals (Brodeur et al, 1997;Norris, 2000;Lévesque et al, 2002).…”

Characterization of Phase I biotransformation enzymes in coho salmon (Oncorhynchus kisutch)

“…Water quality monitoring conducted by the United States Geological Survey (Gilliom et al, 2006) have indicated that many Pacific Northwest surface waters contain pesticide residues, oftentimes in river beds used by salmon for spawning and during the early life stages of the fry (Scholz et al, 2006). Pollutants in water may affect the physiology of fish olfaction, disrupting biologically-relevant signals essential in their behavior that ultimately affect species survival (Klaprat et al, 1992;Moore & Waring, 1996;Scott et al, 2003). Accordingly, it is important to understand the expression and catalytic activities of the gene products of biotransformation enzymes in olfactory, branchial, and hepatic tissues to help understand the susceptibility of Pacific salmon to aquatic pollutants.…”

Behavioural and physiological responses to ­pharmaceutical exposure in macroalgae and ­grazers from a Baltic Sea littoral community

“…all individuals re spond irrespective of whether they have been previously exposed, or induced, which means that a naive individual will not respond or will show a weaker response than an experienced individual. Effects on predator recognition have previously been demonstrated in fish and tadpoles exposed to acidification, pesticides and heavy metals (Scott et al 2003, Mandrillon & Saglio 2007. Scott et al (2003) also found that the effect of the contaminant on behaviour was only present after waterborne exposure.…”

“…Effects on predator recognition have previously been demonstrated in fish and tadpoles exposed to acidification, pesticides and heavy metals (Scott et al 2003, Mandrillon & Saglio 2007. Scott et al (2003) also found that the effect of the contaminant on behaviour was only present after waterborne exposure. To our knowledge, no experiments prior to this have been performed on the effects of pharmaceuticals on predator−prey interactions.…”