scholarly journals Impaired detection of chemical alarm cues by juvenile wild Atlantic salmon (Salmo salar) in a weakly acidic environment

2006 ◽  
Vol 63 (10) ◽  
pp. 2356-2363 ◽  
Author(s):  
Antoine Olivier Henri Claude Leduc ◽  
Ellie Roh ◽  
Mark Charles Harvey ◽  
Grant Edwin Brown
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Alarm Cues ◽  
Multiple Streams ◽  
Age Classes ◽  
Atlantic Salmon Salmo Salar ◽  
Chemical Alarm Cues ◽  
Young Of The Year ◽  
Single Field ◽  
Acidity Level

Many prey fishes rely on damage-released chemical alarm cues to detect and avoid predators. The ability to use these cues has been shown to confer considerable survival benefits to individuals. While several laboratory studies and a single field study have demonstrated that an ambient pH of 6.0 impairs fishes in their ability to detect these alarm cues, no study had yet compared the response to alarm cue exposures across populations residing in multiple streams of a different acidity level. In our study, we conducted live behavioural observations in five nursery streams, ranging in pH from 5.71 to 7.49 on two age classes (young of the year and parr) of wild juvenile Atlantic salmon (Salmo salar). We aimed to assess if the detection of these chemical alarm cues was constantly dependant on the ambient pH or if variations in the detection occurred among populations of the different streams regardless of the ambient acidity level. Our results demonstrated that salmon present in any acidic stream did not respond to alarm cues, while those in neutral streams exhibited typical alarm responses.

Predation costs of impaired chemosensory risk assessment on acid-impacted juvenile Atlantic salmon (Salmo salar)

2014 ◽  
Vol 71 (5) ◽  
pp. 756-762 ◽  
Author(s):  
Chris K. Elvidge ◽  
Grant E. Brown
Keyword(s):  
Risk Assessment ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Brook Trout ◽  
Predatory Fish ◽  
Alarm Cues ◽  
Compensatory Mechanisms ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Chemical Alarm Cues

Weak levels of acidification (pH < 6.6) inhibit the ability of fishes to assess predation risk via interference with damage-released chemical alarm cues. While survival benefits associated with behavioural responses to alarm cues have been demonstrated under laboratory conditions, it remains largely unknown whether fishes under natural conditions experience similar benefits. Using hatchery-reared juvenile Atlantic salmon (Salmo salar) as a model organism, we conducted a tethering experiment in reaches of neutral (pH ≥ 6.6) and acidic (pH < 6.6) salmon nursery streams, plus one additional stream that varied between pH classes. Despite exposure to fewer predatory fish species, similar availability of physical refugia, and similar threat from terrestrial predators, tethered fish in acidic streams were significantly more likely to be predated over the course of a trial than their counterparts in neutral streams. These results suggest that (i) in the absence of compensatory mechanisms, juvenile Atlantic salmon under acidic conditions may experience greater rates of predation as a result of impaired chemosensory risk assessment, and (ii) brook trout (Salvelinus fontinalis) appear to play the greatest role in limiting the survival of young-of-the-year (0+) salmon.

Effects of acid rainfall on juvenile Atlantic salmon (Salmo salar) antipredator behaviour: loss of chemical alarm function and potential survival consequences during predation

2009 ◽  
Vol 60 (12) ◽  
pp. 1223 ◽  
Author(s):  
Antoine O. H. C. Leduc ◽  
Ellie Roh ◽  
Grant E. Brown
Keyword(s):  
Rainbow Trout ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Antipredator Behaviour ◽  
Chemical Information ◽  
Alarm Cues ◽  
Episodic Acidification ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Chemical Alarm Cues

Many organisms rely on chemosensory cues to mediate predation risks. Recent studies have demonstrated impaired chemosensory detection ability under weak acidification. Because rainfall may lead to episodic acidification of surface water, we assessed the effects of acid rain on chemosensory alarm functions. Under natural conditions, we quantified alarm behaviour of juvenile Atlantic salmon (Salmo salar) exposed to conspecific chemical alarm cues before and following rainfall. Before rainfall, salmon were capable of an alarm response in the study streams. After rainfall, salmon from Devil’s Brook did not respond to the alarm cues whereas the detection of salmon from Catamaran Brook (a comparable stream having higher acid neutralising capacity) was maintained. To relate these findings to predator–prey encounters, we performed a second experiment where we staged encounters between prey (rainbow trout, Oncorhynchus mykiss) and predator (largemouth bass, Micropterus salmoides) exposed to acidified and unacidified rainbow trout chemical alarm cues. Trout exposed to acidified alarm cues survived for a significantly shorter amount of time than trout exposed to unacidified alarm cues, whereas no difference in overall predator behaviour was observed. Our results suggest that episodic acidification in small nursery streams may disrupt the chemical information mediated by the chemical alarm cues that can translate into higher survival costs for prey.

scholarly journals Do juvenile Atlantic salmon (Salmo salar) use chemosensory cues to detect and avoid risky habitats in the wild?

2011 ◽  
Vol 68 (4) ◽  
pp. 655-662 ◽  
Author(s):  
Jae-Woo Kim ◽  
James W.A. Grant ◽  
Grant E. Brown
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Stream Water ◽  
Alarm Cues ◽  
Alarm Cue ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Chemical Alarm Cues ◽  
In The Wild ◽  
Experimental Treatments

We examined whether juvenile Atlantic salmon ( Salmo salar ) in the wild adjust their behaviour in response to chemical cues of predator activity during a 4-week period after emergence from gravel nests. In each of seven 75 m2 sites in Catamaran Brook, New Brunswick, Canada, we established three contiguous sections differing in perceived predator activity by releasing stream water in control sections, conspecific alarm cues in risky sections, and nothing in buffer sections in both 2006 and 2007. As predicted, the density of young-of-the-year (YOY) salmon tended to decrease in alarm cue sections, while it increased in control and buffer sections. After the 2-week manipulation in 2006, we switched treatments so that buffer sections became alarm cue sections and alarm cue sections became buffer sections for an additional 2-week period. After the switch, the number of YOY increased least in the new alarm cue sections and most in control and new buffer sections. In contrast with YOY, the density of age 1+ parr was not affected by the experimental treatments. Our results suggest that YOY salmon can use chemical alarm cues to assess the predator activity of habitats in the wild.

Differences in antipredator behaviour between wild and hatchery-reared juvenile Atlantic salmon (Salmo salar) under seminatural conditions

2011 ◽  
Vol 68 (12) ◽  
pp. 2157-2166 ◽  
Author(s):  
Christopher D. Jackson ◽  
Grant E. Brown
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Antipredator Behaviour ◽  
Source Population ◽  
Alarm Cues ◽  
Natural Conditions ◽  
Atlantic Salmon Salmo Salar ◽  
Chemical Alarm Cues ◽  
Two Generations ◽  
Differential Experience

Captive rearing may elicit experiential or genetically based changes to salmonid antipredator behaviour, which may reduce survival of hatchery-reared fishes when they are released into the wild. Nevertheless, few studies have compared the behaviour between local wild-caught and local hatchery-reared fish (two generations or less), and none have done so under natural conditions. We conducted a seminatural field study comparing the antipredator behaviour of wild-caught, F1 (offspring of wild-caught adults) with that of F2 (second generation) hatchery-reared young-of-the-year Atlantic salmon ( Salmo salar , from the same source population) in response to standardized chemical alarm cues. Wild-caught salmon exhibited the strongest antipredator response to a standardized threat (conspecific alarm cues), while F2 salmon exhibited the weakest response. F1 salmon were intermediate in their behavioural response. The observed differences between wild-caught and F1 salmon suggests that differential experience may play a significant role in predator avoidance behaviours. Furthermore, the observed differences between F1 and F2 salmon suggests that even one full generation of hatchery rearing may be sufficient to select for maladaptive responses to predators under natural conditions. Given the controversy regarding the effectiveness of hatchery programs for conservation use, the results of this study suggest that minimizing hatchery time may reduce the behavioural differences between wild and hatchery-reared fishes.

Mechanisms underlying the increase in young-of-the-year Atlantic salmon (Salmo salar) density with habitat complexity

2008 ◽  
Vol 65 (9) ◽  
pp. 1956-1964 ◽  
Author(s):  
Oscar Venter ◽  
James W.A. Grant ◽  
Michelle V. Noël ◽  
Jae-woo Kim
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Habitat Complexity ◽  
Indirect Evidence ◽  
Growth Potential ◽  
Territory Size ◽  
Complex Environments ◽  
Atlantic Salmon Salmo Salar ◽  
Direct Support ◽  
Young Of The Year

We tested three hypotheses used to explain the increase in young-of-the-year (YOY) Atlantic salmon ( Salmo salar ) density with habitat complexity: the territory-size, predator-refuge, and foraging-benefits hypotheses. We manipulated habitat complexity in three different treatments (boulder-removed, control, and boulder-added) at eight sites in Catamaran Brook and the Little Southwest Miramichi River, New Brunswick. The density of juvenile salmon was two times higher in the boulder-added treatment than in the other treatments. Our data were consistent with the territory-size hypothesis; visual isolation was highest and territory size was smallest in the boulder-added treatment, and salmon selected microhabitats to maximize their field of view. Our results showed partial support for the predator-refuge hypothesis; salmon in the boulder-added sites were closer to cover and showed a reduced reaction distance to a novel stimulus, but did not preferentially select microhabitats closer to cover. We found no direct support for the foraging-benefits hypothesis; however, there is indirect evidence that boulders may improve the growth potential of instream habitat. Our results suggest that YOY Atlantic salmon may be attracted to complex environments for the increased cover and that the decreased visibility of these sites causes a reduction in territory size, allowing a higher density of fish.

Changes in the Selection of Microhabitat by Juvenile Atlantic Salmon (Salmo salar) at the Summer–Autumn Transition in a Small River

1984 ◽  
Vol 41 (3) ◽  
pp. 469-475 ◽  
Author(s):  
D. M. Rimmer ◽  
U. Paim ◽  
R. L. Saunders
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Water Depth ◽  
Water Velocity ◽  
Bottom Surface ◽  
Age Classes ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Wide Range ◽  
Maximum Water

Over three summers we used direct underwater observation to examine the summer to autumn differences in seven microhabitat properties of three age-classes of juvenile Atlantic salmon (Salmo salar) in the Little Sevogle River of northeastern New Brunswick. Salmon of all three age-classes occupied a wide range of water depths during summer, but were concentrated mainly in depths of 24–36 cm. In autumn, they occurred in this range almost exclusively. The streambed stones most closely associated with the individual positions of all ages were always <20 cm in summer and mostly (84–92%) <10 cm in diameter. In autumn, all ages were associated with home stones up to 40 cm in diameter, with 65–83% of the stones exceeding 20 cm; the size of home stones selected increased with fish age in autumn. There was no apparent relationship between the water depth and home stone size distributions occupied by all age-classes and available in the stream during either summer or autumn. Summer focal water velocity (velocity at the fish's snout) was predominantly 10–30 cm∙s−1 for 0+, 10–40 cm∙s−1 for 1+, and 30–50 cm∙s−1 for 2+ salmon, but during autumn it was almost always <10 cm∙s−1 for all ages. The bottom and surface water velocities as well as the maximum water velocity within 1 m of fish stations increased with fish age during summer and autumn. At the summer–autumn transition, 0+ salmon selected higher bottom, surface, and maximum water velocities, 2+ salmon selected lower velocities, but selection by 1+ salmon remained unchanged. We view substrate size followed by water depth as the primary properties influencing stream suitability for juvenile Atlantic salmon in autumn.

Patterns and correlates of movement and site fidelity in individually tagged young-of-the-year Atlantic salmon (Salmo salar)

2003 ◽  
Vol 60 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Stefán Ó Steingrímsson ◽  
James W.A Grant
Keyword(s):  
Atlantic Salmon ◽  
Habitat Use ◽  
Salmo Salar ◽  
Site Fidelity ◽  
Population Regulation ◽  
Fish Movement ◽  
Population Densities ◽  
Atlantic Salmon Salmo Salar ◽  
Young Of The Year ◽  
Study Sites

The literature on stream fish movement offers diverse views on the patterns (restricted vs. nonrestricted), causes (competition vs. habitat use), and consequences (mobile fish of lower vs. equal fitness) of movement. We tagged 320 young-of-the-year Atlantic salmon (Salmo salar) (30.1–55.3 mm), using relatively noninvasive tagging (elastomers) and recovery (snorkeling) techniques, to test these alternative views. Most fish (mean = 63.8%) stayed in the study sites (10–120 m) throughout their respective study season (28–74 days). Of the resighted fish, 61.8% moved less than 1 m up- or down-stream and only three fish moved more than 10 m, causing extremely leptokurtic movement curves. Movement and site fidelity were weakly affected by habitat use and competition. Fish originally found in slow water moved farther than fish from fast water, whereas fish found at high population densities were more likely to disappear than fish from low densities. Finally, mobile fish grew as fast or faster than more sedentary fish, supporting the idea that movement can be advantageous and is not just a by-product of density-dependent population regulation.

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