Morphological and behavioural differences among recently-emerged brook charr,Salvelinus fontinalis, foraging in slow- vs. fast-running water

Abstract

SynopsisMorphology and resource use were compared among recently-emerged brook charr, Salvelinus fontinalis, sampled from field locations differing in current speed . Individuals from faster running water were slightly longer, and had more fusiform body shapes and larger caudal fin heights, than individuals from slower running water. In addition, individuals from faster running water also directed more foraging attempts toward the middle of the water column and fewer toward the benthos and water surface . They also ate more dipteran larvae, fewer aquatic crustaceans, and fewer insect pupae and adults . Individuals located in the slowest and fastest current speeds made fewer foraging attempts per min, on average, than individuals located in current speeds of intermediate magnitude . Dry weight of stomach contents did not vary significantly with current speed, however . The form of the relationship between body shape and current speed suggests that it is adaptive . Small-scale variation in the location of foraging sites may account for some of the individual variability in resource use often reported for stream salmonids . Variation in the locations of foraging sites may also entail a trade-off between an individual's swimming effort and the quality of prey it consumes . IntroductionStudies comparing individuals varying in morphology, physiology, or behaviour can be valuable in a variety of contexts including (i) evaluating the role that individual variation plays in the mechanisms regulating population sizes (DeAngelis et al . 1991), and (ii) establishing functional links between morphology or physiology and other aspects of an individual's ecology (e .g . habitat use, diet) (Ehlinger

Morphological variation of pumpkinseed (Lepomis gibbosus) with emphasis on allometry

“…*2 Multiple factor ANOVA results after standardization. Grant, 1994;Brinsmead and Fox, 2002;Naspleda et al, 2012). According to Naspleda et al (2012), only greater pelvic and pectoral fin lengths in stream fishes are consistent with hydrodynamic theory, whereas another dataset (Brinsmead and Fox, 2002) shows no significant differences between habitats according to these lengths.…”

Old wine in new bottles: reaction norms in salmonid fishes

“…This work was followed in 1994 by behavioural and life-history studies on brook trout, Salvelinus fontinalis (McLaughlin and Grant, 1994), and Atlantic salmon (Hutchings and Myers, 1994), and on resource polymorphisms in a number of fishes, including salmonids (Robinson and Wilson, 1994).…”

Fin development in stream- and hatchery-reared Atlantic salmon

“…Caudal fins are actively used for burst swimming (Vogel, 1981), and larger caudal fins among fish from the Chickley River would provide an advantage for swimming against the faster moving water. McLaughlin and Grant (1994) have found caudal fin heights to be larger in brook charr (Salvelinus fontinalis) in faster moving water. By experimentally placing Atlantic salmon and brown trout (Salmo trutta) in raceways with different water velocities, Pakkasmaa and Piironen (2001) determined that caudal fins were larger among fish in faster flowing water after 4 weeks.…”