Responses of macroinvertebrate drift, benthic assemblages, and trout foraging to hydropeaking

2014 ◽  
Vol 71 (5) ◽  
pp. 675-687 ◽  
Author(s):  
Scott W. Miller ◽  
Sarah Judson
Keyword(s):  
Rainbow Trout ◽  
Food Webs ◽  
Benthic Assemblages ◽  
Double Peak ◽  
Taxa Richness ◽  
Absolute Flow ◽  
Gut Fullness ◽  
Peak Release ◽  
Tail Water ◽  
Macroinvertebrate Drift

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.

scholarly journals First study of food webs in a large glacial river: the trophic role of invasive trout

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Marina Tagliaferro ◽  
Sean P. Kelly ◽  
Miguel Pascual
Keyword(s):  
Rainbow Trout ◽  
Food Webs ◽  
Fish Species ◽  
Lake Trout ◽  
Trophic Position ◽  
Life Stage ◽  
Trophic Levels ◽  
Basal Resources ◽  
Ecological Importance ◽  
Δ15n And Δ13c

Abstract The aim of this study was to determine the food webs structure of a large Patagonian river in two river sections (Upstream and Midstream) and to evaluate isotopic overlap between native and introduced species. We used stable isotope analyses of δ15N and δ13C and stomach content. The Upstream section had a more complex food webs structure with a greater richness of macroinvertebrates and fish species than Midstream. Upstream basal resources were dominated by filamentous algae. Lake Trout were found to have a higher trophic position than all other fish species in that area although, the most abundant fish species, were Rainbow Trout. Depending on the life stage, Rainbow Trout shifted from prey to competitor/predator. In the Midstream section, the base of the food webs was dominated by coarse particulate organic matter, and adult Rainbow Trout had the highest trophic level. Isotopic values changed among macroinvertebrates and fish for both areas. The two most abundant native and invasive species — Puyen and Rainbow Trout — showed an isotopic separation in Midstream but did not in Upstream areas. The presence of invasive fish that occupy top trophic levels can have a significant impact on native fish populations that have great ecological importance in the region.

Recycling of Elements Transported Upstream by Runs of Pacific Salmon: I, δ15N and δ13C Evidence in Sashin Creek, Southeastern Alaska

1990 ◽  
Vol 47 (1) ◽  
pp. 136-144 ◽  
Author(s):  
Thomas C. Kline Jr. ◽  
John J. Goering ◽  
Ole A. Mathisen ◽  
Patrick H. Poe ◽  
Patrick L. Parker
Keyword(s):  
Rainbow Trout ◽  
Food Webs ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Organic C ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Control Section ◽  
The Difference ◽  
Δ15n And Δ13c

Values of δ15N and δ13C (the per mil deviation from the recognized isotope standard) from biota of a southeastern Alaska stream (Sashin Creek) that receives an annual run of 30 000 anadromous pink salmon (Oncorhynchus gorbuscha) were measured to determine sources of nitrogen (N) and carbon (C). Marine-derived nitrogen (MDN) is the predominant source of N for food webs found in the lower 1200 m of the stream which, due to a waterfall, is the only portion of the stream available to salmon returning to spawn. Comparable spawning section biota were enriched by about 5 per mil relative to the salmon-free control section, corresponding to the difference between 0 and 100% MDN in a mixing model. Food webs of resident rainbow trout (O. mykiss), at the outlet of one of the source lakes, Sashin Lake, have very low δ13C, suggesting the importance of a respired C pool in the lake. The source of C in the remainder of the stream is C fixation by autochthonous producers and marine organic C (within the salmon spawning section). Resident fishes in the salmon spawning section depend on MDN and some of the C delivered by the annual run of returning salmon.

The essential oils of some medicinal plants on the immune system of rainbow trout (Oncorhynchus mykiss)

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
A Ghasemi Pirbalouti ◽  
E Pirali ◽  
G Pishkar ◽  
S Mohammadali Jalali ◽  
M Reyesi ◽  
...  
Keyword(s):  
Immune System ◽  
Rainbow Trout ◽  
Medicinal Plants ◽  
Oncorhynchus Mykiss ◽  
Essential Oils ◽  
Rainbow Trout Oncorhynchus Mykiss

Swim bladder mycosis in farmed rainbow trout Oncorhynchus mykiss caused by Phoma herbarum and experimental verification of pathogenicity

2020 ◽  
Vol 138 ◽  
pp. 237-246 ◽  
Author(s):  
J Řehulka ◽  
A Kubátová ◽  
V Hubka
Keyword(s):  
Rainbow Trout ◽  
Histopathological Examination ◽  
Periodic Acid ◽  
Bladder Wall ◽  
Swim Bladder ◽  
Cell Reactivity ◽  
Periodic Acid Schiff ◽  
Posterior Portion ◽  
Hepatic Congestion ◽  
Phoma Herbarum

In this study, spontaneous swim bladder mycosis was documented in a farmed fingerling rainbow trout from a raceway culture system. At necropsy, the gross lesions included a thickened swim bladder wall, and the posterior portion of the swim bladder was enlarged due to massive hyperplasia of muscle. A microscopic wet mount examination of the swim bladder contents revealed abundant septate hyphae, and histopathological examination showed periodic acid-Schiff-positive mycelia in the lumen and wall of the swim bladder. Histopathological examination of the thickened posterior swim bladder revealed muscle hyperplasia with expansion by inflammatory cells. The causative agent was identified as Phoma herbarum through morphological analysis and DNA sequencing. The disease was reproduced in rainbow trout fingerlings using intraperitoneal injection of a spore suspension. Necropsy in dead and moribund fish revealed extensive congestion and haemorrhages in the serosa of visceral organs and in liver and abdominal serosanguinous fluid. Histopathological examination showed severe hepatic congestion, sinusoidal dilatation, Kupffer cell reactivity, leukostasis and degenerative changes. Fungi were disseminated to the liver, pyloric caeca, kidney, spleen and heart. Although infections caused by Phoma spp. have been repeatedly reported in fish, species identification has been hampered by extensive taxonomic changes. The results of this study confirmed the pathogenicity of P. herbarum in salmonids by using a reliably identified strain during experimental fish infection and provides new knowledge regarding the course of infection.

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