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Oecologia

Title:		Detection of conspecific alarm cues by juvenile salmonids under neutral and weakly acidic conditions: laboratory and field tests
Author(s):		Leduc AO; Kelly JM; Brown E;
Address:		"Department of Biology, Concordia University, 7141 Sherbrooke O, H4B 1R6, Montreal, Quebec, Canada. aleduc@alcor.concordia.ca"
Journal Title:		Oecologia
Year:		2004
Volume:		20040131
Issue:		2
Page Number:		318 - 324
DOI:		10.1007/s00442-004-1492-8
ISSN/ISBN:		0029-8549 (Print) 0029-8549 (Linking)
Abstract:		"A variety of fishes possess damage-released chemical alarm cues, which play a critical role in the detection and avoidance of potential predation threats. Recently, we have demonstrated that the ability of fathead minnows ( Pimephales promelas) and finescale dace ( Phoxinus neogaeus) to detect and respond to conspecific alarm cues is significantly reduced under weakly acidic conditions (pH 6.0). Rainbow trout ( Oncorhynchus mykiss) and brook charr ( Salvelinus fontinalis) possess an analogous alarm cue system. However, it is unknown if the trout alarm cue system is likewise affected by relatively small changes in pH. In addition, previous studies have not verified this phenomenon under natural conditions. We conducted laboratory and field trials to examine the potential effects of acute exposure to weakly acidic (pH 6.0) conditions on the detection and response of conspecific alarm cues by juvenile trout. Our laboratory results demonstrate that while juvenile rainbow trout exhibit significant increases in antipredator behaviour under normal pH conditions (pH 7.0-7.2), they do not respond to the presence of conspecific chemical alarm cues (i.e. response is not different from controls) under weakly acidic conditions. Similarly, a wild strain of brook charr in their natural streams near Sudbury, Ontario, failed to detect conspecific alarm cues in a weakly acidic stream (mean pH 6.11) while they responded to these cues in a neutral stream (mean pH of 6.88). This is the first demonstration that relatively small changes in ambient pH can influence alarm responses under natural conditions. These data suggest significant, sub-lethal effects of acid precipitation on natural waterways"
Keywords:		Acid Rain/*adverse effects Animals Hydrogen-Ion Concentration Oncorhynchus mykiss/*physiology *Pheromones Population Dynamics Predatory Behavior Smell Trout/*physiology;
Notes:		"MedlineLeduc, Antoine O H C Kelly, Jocelyn M E Brown, Grant eng Research Support, Non-U.S. Gov't Germany 2004/02/06 Oecologia. 2004 Apr; 139(2):318-24. doi: 10.1007/s00442-004-1492-8. Epub 2004 Jan 31"