The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
David L.g. Noakes - One of the best experts on this subject based on the ideXlab platform.
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Temporal persistence of resource polymorphism in brook charr, Salvelinus fontinalis
Environmental Biology of Fishes, 2001Co-Authors: István Imre, Robert L. Mclaughlin, David L.g. NoakesAbstract:Resource polymorphisms are believed to be an important intermediate step in competitive sympatric speciation. Reports of resource polymorphisms in fishes are becoming more common, but tests of the temporal persistence of resource polymorphisms remain scarce. We examined the temporal persistence of a body shape dimorphism reported previously for stream dwelling young-of-the-year brook charr, Salvelinus fontinalis, inhabiting slow vs. fast running water. In the year of our study, we found no difference in body shape between individuals in slow vs. fast flowing water, although fish in fast flowing water were of greater standard length than those in slower flowing water. We conclude that the resource polymorphism reported earlier for brook charr in streams is not stable temporally.
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groundwater and the incubation and emergence of brook trout Salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Allen R Curry, David L.g. Noakes, George E MorganAbstract:Groundwater was observed to discharge through brook trout (Salvelinus fontinalis) redds during the November to April incubation period in Canadian Shield waters. Groundwater was important for protecting redds from infiltrating surface water and ice. Physical and chemical characteristics of individual redd environments were similar during the incubation period. Substrate temperature and oxygen levels were reduced in nonredd substrates 100 cm from redds. The stability of discharge, temperature, dissolved oxygen, and specific conductance during incubation was similar between redd and nonredd substrates (≤100 cm away). The quality of redd habitats and embryo survival did not appear to be related to female competition for redd sites or time of spawning. There was evidence of density-dependent control of spawning success and the adaptive nature of alevin emergence behaviour in Canadian Shield waters.
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groundwater and the selection of spawning sites by brook trout Salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Allen R Curry, David L.g. NoakesAbstract:Spawning areas selected by brook trout (Salvelinus fontinalis) displayed variable relationships to discharging groundwater across geologic regions. In Canadian Shield waters, spawning was associated with areas of distinct, discharging groundwater. The specific mechanism of selection could not be determined. Groundwater did not appear to influence the selection of individual redd sites within these discharge areas. Competition among females for the opportunity to spawn in a limited area defined by the discharging groundwater appeared to control the selection of redd sites. In southwestern Ontario streams, discharging groundwater was prominent throughout areas of spawning both at redds and at adjacent, nonspawning substrates (≤7 m). Consequently, relationships between groundwater and spawning site selection were ambiguous. On the unglaciated plateau of central Pennsylvania, no groundwater was observed in redds or nonspawning substrates in streams. Brook trout management programmes must consider these ground...
James W. A. Grant - One of the best experts on this subject based on the ideXlab platform.
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aggressiveness and the foraging behaviour of young of the year brook charr Salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1990Co-Authors: James W. A. GrantAbstract:Individual young-of-the-year brook charr (Salvelinus fontinalis) were observed in the field to relate their aggressiveness to their body size, the size and quality of their foraging site, and their feeding rate. Aggressive charr were 13% larger than nonaggressive conspecifics observed on the same day in the same area. Aggressive fish had a lateral foraging radius 29% larger than nonaggressive fish and a 45% greater mean distance to neighbours, even when the effect of body size was removed by analysis of covariance. Aggressive fish of two size categories (20–29 and 40–99 mm) made 70 and 55% more feeding attempts per unit time, respectively, than nonaggressive fish of the same size. Number of prey items in stomachs was significantly and positively correlated with feeding attempt rate. In addition, aggressive fish appeared to occupy more preferred sites, since their sites were significantly more likely to be reoccupied after their removal than were sites occupied by nonaggressive fish. These results are cons...
George E Morgan - One of the best experts on this subject based on the ideXlab platform.
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groundwater and the incubation and emergence of brook trout Salvelinus fontinalis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Allen R Curry, David L.g. Noakes, George E MorganAbstract:Groundwater was observed to discharge through brook trout (Salvelinus fontinalis) redds during the November to April incubation period in Canadian Shield waters. Groundwater was important for protecting redds from infiltrating surface water and ice. Physical and chemical characteristics of individual redd environments were similar during the incubation period. Substrate temperature and oxygen levels were reduced in nonredd substrates 100 cm from redds. The stability of discharge, temperature, dissolved oxygen, and specific conductance during incubation was similar between redd and nonredd substrates (≤100 cm away). The quality of redd habitats and embryo survival did not appear to be related to female competition for redd sites or time of spawning. There was evidence of density-dependent control of spawning success and the adaptive nature of alevin emergence behaviour in Canadian Shield waters.
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Growth and food of young-of-the-year brook charr,Salvelinus fontinalis, in lake and creek environments
Environmental Biology of Fishes, 1993Co-Authors: R. Allen Curry, Stephanie Allen, George E MorganAbstract:Growth and diet of brook charr,Salvelinus fontinalis, during their first weeks of exogenous feeding were compared between the nearshore zone of a central Ontario lake and its small, inlet creeks. Food selection was related to size and age of charr and possibly availability of food items. Mean growth was similar between habitats despite differences in consumed food types and caloric values. Differences in social behaviour may have been responsible for different patterns of growth between habitats. The importance of creek habitats to the dynamics and fitness of lake populations of brook charr are suggested.
Jeffrey A. Hutchings - One of the best experts on this subject based on the ideXlab platform.
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adaptive phenotypic plasticity in brook trout Salvelinus fontinalis life histories
Ecoscience, 1996Co-Authors: Jeffrey A. HutchingsAbstract:Abstract:I analyzed life history data for three unexploited populations of brook trout, Salvelinus fontinalis, to explore how environmental variation in juvenile (pre-reproductive) growth rate can generate variation in fitness (r) and to quantify the fitness benefits associated with phenotypic plasticity in age at maturity. Within populations, differences in growth rate to maturity are associated with significant variation in fitness through size-dependent effects on life history traits. Among populations, variation in size at maturity effected comparatively little variation in egg size and reproductive allotment (gonad weight/body weight) but was associated with high variability in fecundity and post-reproductive, overwinter survival. The relationship between fitness and the oft-reported negative association between growth rate and age at maturity in indeterminately growing organisms is supported empirically and is shown to vary among populations. Fitness functions are consistent with the prediction that...
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age and size specific costs of reproduction within populations of brook trout Salvelinus fontinalis
Oikos, 1994Co-Authors: Jeffrey A. HutchingsAbstract:Age and size at maturity influence a survival cost of reproduction in brook trout, Salvelinus fontinalis, within three unexploited populations in southeastern Newfoundland, Canada. Post-reproductive, overwinter survival increased significantly with female body size in all three populations but was positively associated with male body size in only one. Reproduction increased the age-specific risk of overwinter mortality by 17-89 % and appears to be costly for brook trout because it reduces the lipid reserves upon which individuals depend to survive winter. This survival cost of reproduction (overwinter survival of reproductive individuals relative to that of non-reproductive individuals) increased with age but was negatively associated with body size within each population
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The independence of enzyme heterozygosity and life-history traits in natural populations of Salvelinus fontinalis (brook trout)
Heredity, 1992Co-Authors: Jeffrey A. Hutchings, Moira M. FergusonAbstract:The independence of enzyme heterozygosity and life-history traits in natural populations of Salvelinus fontinalis (brook trout)
C P Sanford - One of the best experts on this subject based on the ideXlab platform.
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Kinematic analysis of a novel feeding mechanism in the brook trout Salvelinus fontinalis (Teleostei: Salmonidae): behavioral modulation of a functional novelty.
The Journal of experimental biology, 2020Co-Authors: C P SanfordAbstract:The tongue-bite apparatus (TBA) of salmonids represents an impressive novel feeding mechanism. The TBA consists of a set of well-developed teeth on the dorsal surface of the anterior hyoid (basihyal) and an opposing set of teeth on the roof of the mouth (vomer). A kinematic analysis of behaviors associated with the TBA in the brook trout Salvelinus fontinalis was performed using high-speed video (250 frames s(-1)). Two distinct behaviors were identified, raking and open-mouth chewing. Univariate analysis demonstrated that these behaviors were significantly different from one another. The power stroke of raking is characterized by significantly greater neurocranial elevation (raking, 36 degrees; open-mouth chewing, 16 degrees ) and retraction of the pectoral girdle (raking, 0.85 cm or 21 % of head length; open-mouth chewing, 0.41 cm or 10 % of head length). Open-mouth chewing is characterized predominantly by dorso-ventral excursions of the anterior hyoid (open-mouth chewing, 0.26 cm; raking, 0.14 cm). Raking is significantly shorter in duration (mean 49 ms) than open-mouth chewing (mean 77 ms). When presented with three different types of prey (crickets, fish or worms), Salvelinus fontinalis showed no variation in raking behavior, indicating that raking is highly stereotyped. In contrast, when feeding on worms, Salvelinus fontinalis modulated open-mouth chewing behavior with shorter durations to maximum displacement (at least 20 ms shorter than for either fish or cricket), although the magnitude of displacements did not vary. The reasons for the shorter duration of displacement variables while feeding on worms remains unclear. During post-capture processing behaviors in Salvelinus fontinalis, the magnitude of displacement variables is highly variable between individuals, but temporal patterns are not. This study characterizes two novel post-capture feeding behaviors and modulation of those behaviors in salmonids.
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Kinematic analysis of a novel feeding mechanism in the brook trout Salvelinus fontinalis (Teleostei: Salmonidae): behavioral modulation of a functional novelty.
The Journal of Experimental Biology, 2001Co-Authors: C P SanfordAbstract:SUMMARY The tongue-bite apparatus (TBA) of salmonids represents an impressive novel feeding mechanism. The TBA consists of a set of well-developed teeth on the dorsal surface of the anterior hyoid (basihyal) and an opposing set of teeth on the roof of the mouth (vomer). A kinematic analysis of behaviors associated with the TBA in the brook trout Salvelinus fontinalis was performed using high-speed video (250 frames s –1 ). Two distinct behaviors were identified, raking and open-mouth chewing. Univariate analysis demonstrated that these behaviors were significantly different from one another. The power stroke of raking is characterized by significantly greater neurocranial elevation (raking, 36°; open-mouth chewing, 16°) and retraction of the pectoral girdle (raking, 0.85 cm or 21 % of head length; open-mouth chewing, 0.41 cm or 10 % of head length). Open-mouth chewing is characterized predominantly by dorso-ventral excursions of the anterior hyoid (open-mouth chewing, 0.26 cm; raking , 0.14 cm). Raking is significantly shorter in duration (mean 49 ms) than open-mouth chewing (mean 77 ms). When presented with three different types of prey (crickets, fish or worms), Salvelinus fontinalis showed no variation in raking behavior, indicating that raking is highly stereotyped. In contrast, when feeding on worms, Salvelinus fontinalis modulated open-mouth chewing behavior with shorter durations to maximum displacement (at least 20 ms shorter than for either fish or cricket), although the magnitude of displacements did not vary. The reasons for the shorter duration of displacement variables while feeding on worms remains unclear. During post-capture processing behaviors in Salvelinus fontinalis , the magnitude of displacement variables is highly variable between individuals, but temporal patterns are not. This study characterizes two novel post-capture feeding behaviors and modulation of those behaviors in salmonids.
