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We utilized both hydropeaking and experimental flows to quantify responses of macroinvertebrate drift, benthic assemblages, and fish consumption to double-peak release patterns. Our results suggest that changes in discharge may have a greater impact on macroinvertebrate drift than absolute flow levels, such that mean daily drift biomass was significantly higher during double-peaking; however, drift increases were sustained for only 30-60 days despite ongoing hydropeaking. Drift increases were proportional to peak magnitude, with drift biomass peaking during the rising limb of the hydrograph and declining prior to the cessation of peak flows. Both within- and among-day drift hysteresis appeared related to patterns in vegetative export, principally Cladophora and Amblystegium. Increases in macroinvertebrate drift were not associated with detectable reductions in benthic densities, while we observed inconsistent and modest taxa richness reductions. Lastly, gut fullness for both brown and rainbow trout increased significantly following periods of hydropeaking, suggesting that the effects of double-peaking can propagate through tail-water food webs. Nous avons utilise des laches d'eau lies a la demande hydroelectrique et des debits experimentaux pour quantifier les reactions de la derive de macroinvertebres, des assemblages benthiques et de la consommation des poissons a des motifs de laches doubles. Nos resultats portent a croire que les variations de debit pourraient avoir une plus grande incidence sur la derive de macroinvertebres que la valeur absolue des debits, la biomasse derivante quotidienne etant significativement plus grande quand des laches doubles etaient utilises; cela dit, les augmentations de la derive n'etaient maintenues que de 30 a 60 jours, meme si les laches se poursuivaient sur une plus longue periode. Les augmentations de la derive etaient proportionnelles a la magnitude des laches, la biomasse derivante atteignant son maximum pendant la branche montante de l'hydrogramme, puis diminuant avant la cessation des debits de pointe. Des hysteresis quotidiennes et sur plusieurs jours etaient associees a des motifs d'exportation vegetale, principalement de Cladophora et d'Amblystegium. Si les augmentations de la derive de macroinvertebres n'etaient pas associees a des reductions perceptibles des densites benthiques, des reductions modestes et non uniformes de la richesse taxonomiques ont ete observees. Enfin, le contenu du tube digestif augmentait significativement tant pour la truite brune que pour la truite arc-en-ciel dans la foulee de periodes de laches lies a la demande, ce qui donne a penser que les effets des laches doubles peuvent se propager dans les reseaux trophiques des eaux d'aval. [Traduit par la Redaction], Introduction The construction and management of over 7700 large dams (>15 m high) throughout the United States has fundamentally altered the chemical, physical, and biological components of many lotic ecosystems [...]

Abstract: Native salmonid fishes often face simultaneous threats from habitat fragmentation and invasion by nonnative trout species. Unfortunately, management actions to address one may create or exacerbate the other. A [...]

Abstract: We hypothesized that body shape differences between Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri), rainbow trout (Oncorhynchus mykiss), and their hybrids may influence swimming ability and thus play an important [...]

Research has been conducted on male sneaking behavior of Atlantic salmon which leads to interspecific hybridization. Results demonstrate that this behavior helps sneaking Atlantic salmon males to fertilize brown trout ova in absence of brown trout males and that brown trout male aggressiveness towards sneaking salmon males and low survival of salmon sneaker hybrids are interspecific barriers.

Lanscaped seminatural stream channels were utilized to determine whether the formation of social heirarchies are influenced by similar factors as single and mixed-species of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). Feeding was also analyzed to see if dominant and subordinate individuals feed at the same time and of they have similar feeding rythms during the day.

The effect of major histocompatibility complex (MHC) on kin discrimination was studied in the juvenile Arctic charr, Salvelinus alpinus. The findings revealed that the fish can distinguish between self and nonself MHC genotypes among siblings, thereby indicating that sibling recognition was controlled by MHC. The results further indicated that discrimination of the genotype of particular MHC class II B, exon two locus, as well as other related loci from conspecifics are accomplished via olfactory cues.

The presence of morphological defense appendages and strategies of an invasive amphipod (Gammarus roeseli), which protects it from the predation of brown trout (Salmo trutta fario), is discussed.