Terrestrial invertebrates as salmonid prey and nitrogen sources in streams: contrasting old-growth and young-growth riparian forests in southeastern Alaska, U.S.A.

1997 ◽  
Vol 54 (6) ◽  
pp. 1259-1269 ◽  
Author(s):  
Mark S Wipfli
Keyword(s):  
Statistical Power ◽  
Coho Salmon ◽  
Fork Length ◽  
Cutthroat Trout ◽  
Timber Harvesting ◽  
Trophic Levels ◽  
Old Growth ◽  
Nitrogen Inputs ◽  
Significant Difference ◽  
Young Growth

Terrestrial-derived invertebrate (TI) inputs into streams and predation on them by salmonids (40-180 mm fork length) were measured in six coastal Alaska stream reaches from April through October 1993-1994; riparian habitat of three stream reaches contained conifer-dominated old-growth (no timber harvesting) and three were alder-dominated young-growth (31 years postclearcutting). Data from pan-traps placed on stream surfaces showed that TI biomass and nitrogen inputs averaged up to 66 and 6 mg ·m-2 ·day-1, respectively, with no significant difference between habitats. Stomach contents from coho salmon (Oncorhynchus kisutch), cutthroat trout (O. clarki), and Dolly Varden (Salvelinus malma) revealed that TI and aquatic-derived invertebrates (AI) were equally important prey. Additionally, salmonids from young-growth systems ingested a greater TI proportion than those from old-growth systems. There were trends but no significant differences between habitats of TI and AI biomass ingested; however, statistical power was <0.30. These results showed that TI were important juvenile salmonid prey and that a riparian overstory with more alder and denser shrub understory may increase their abundance. Riparian vegetation management will likely have important consequences on trophic levels supporting predators, including but not limited to fishes.

Decomposition and nutrient dynamics of ponderosa pine needles in a Mediterranean-type climate

1992 ◽  
Vol 22 (3) ◽  
pp. 306-314 ◽  
Author(s):  
Stephen C. Hart ◽  
Mary K. Firestone ◽  
Eldor A. Paul
Keyword(s):  
Sierra Nevada ◽  
Ponderosa Pine ◽  
Nutrient Dynamics ◽  
Decay Rates ◽  
Litter Fall ◽  
Decomposition Rates ◽  
Old Growth ◽  
Old Growth Forest ◽  
Significant Difference ◽  
Young Growth

A litter-bag technique was used to measure decay rates and assess changes in organic and inorganic constituents of ponderosa pine (Pinusponderosa Laws.) needle litter during decomposition over a 2-year period in old- and young-growth forests in the Sierra Nevada of California. Rates of mass loss were among the lowest reported for temperate and boreal forests, with annual decomposition constants of about 0.08 and 0.18 year−1 for the old- and young-growth forests, respectively. Apparently, the temporal separation of warm temperatures and moist conditions found in Mediterranean-type climates severely limits decomposition in these coniferous forests. In the old-growth forest, comparison of estimates of tree nutrient uptake with net releases of nutrients from fine litter during their 1st year of decomposition suggests that recent litter fall potentially acts as a significant source of P, Mg, and K for tree uptake in this forest; in contrast, recently fallen litter acts as a net sink for N, S, and Ca. Despite initially lower indices of litter quality for litter originating from the old–growth relative to the young–growth forest, no significant difference in decomposition rates of these two litter age-classes was found when placed at either site. This result does not support the hypothesis that decreases in decomposition rates during forest development are driven by decreases in the quality of litter fall.

Stomach Flushing: Effectiveness and Influence on Survival and Condition of Juvenile Salmonids

1978 ◽  
Vol 35 (10) ◽  
pp. 1359-1363 ◽  
Author(s):  
William R. Meehan ◽  
Richard A. Miller
Keyword(s):  
Coho Salmon ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Wild Fish ◽  
Key Words Stomach ◽  
Hatchery Fish ◽  
Juvenile Salmonids ◽  
Significant Difference ◽  
Change In Mean

Hydraulic stomach flushing was an effective method to analyze relative food consumption and feeding habits of young salmonids. Coho salmon (Oncorhynchus kisutch) stomachs were most effectively flushed — 99% of invertebrate organisms (96% of weight of stomach contents); 92% of organisms (83% of weight) were flushed from cutthroat trout (Salmo clarki) stomachs, 90% of organisms (77% of weight) were flushed from rainbow trout (S. gairdneri) stomachs. Stomach flushing did not affect survival of juvenile coho salmon. A significant difference in change in mean condition factor between wild and hatchery fish was found after 30 d (greater change in wild fish), and a significant change was observed between the mean condition factors of control and treated hatchery fish. No difference was found between control and treated wild fish. Key words: stomach flushing, juvenile salmonids, survival, condition, food habits

Marine carbon and nitrogen in southeastern Alaska stream food webs: evidence from artificial and natural streams

2002 ◽  
Vol 59 (8) ◽  
pp. 1257-1265 ◽  
Author(s):  
Dominic T Chaloner ◽  
Kristine M Martin ◽  
Mark S Wipfli ◽  
Peggy H Ostrom ◽  
Gary A Lamberti
Keyword(s):  
Food Webs ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Cutthroat Trout ◽  
Aquatic Organisms ◽  
Trophic Levels ◽  
Total N ◽  
Natural Streams ◽  
Chironomid Midges ◽  
Stream Food Webs

Incorporation of marine-derived nutrients (MDN) into freshwater food webs of southeastern Alaska was studied by measuring the natural abundance of nitrogen and carbon stable isotopes in biota from artificial and natural streams. Biofilm, aquatic macroinvertebrates (detritivores, shredders, and predators), and fish (coho salmon, Oncorhynchus kisutch, and cutthroat trout, Oncorhynchus clarki) were sampled from streams in which Pacific salmon (Oncorhynchus spp.) carcasses had been artificially placed or were present naturally. In the presence of carcasses, all trophic levels incorporated marine-derived nitrogen (range, 22–73% of total N) and carbon (range, 7–52% of total C). In general, chironomid midges assimilated more marine-derived nitrogen and carbon than did other consumers. The assimilation of MDN by aquatic organisms and subsequent isotopic enrichment (5–6‰ for 15N, 3–4‰ for 13C) were similar in experimentally and naturally carcass-enriched streams. For specific taxa, however, percent assimilation for marine nitrogen and carbon were often dissimilar, possibly because of fractionation or transfer inefficiencies. These results suggest that pathways of MDN incorporation into stream food webs include both consumption of salmon material by macroinvertebrates and fish and uptake of mineralized MDN by biofilm. Incorporation of MDN into multiple trophic levels demonstrates the ecological significance of annual returns of anadromous fishes for sustaining the productivity of freshwater food webs.

scholarly journals A simulation study investigating potential diffusion-based MRI signatures of microstrokes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rafat Damseh ◽  
Yuankang Lu ◽  
Xuecong Lu ◽  
Cong Zhang ◽  
Paul J. Marchand ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Statistical Power ◽  
Barrel Cortex ◽  
Signal Loss ◽  
Nuclear Spins ◽  
Directional Diffusion ◽  
Ischemic Tissue ◽  
Significant Difference ◽  
Before And After ◽  
Experimental Validations

AbstractRecent studies suggested that cerebrovascular micro-occlusions, i.e. microstokes, could lead to ischemic tissue infarctions and cognitive deficits. Due to their small size, identifying measurable biomarkers of these microvascular lesions remains a major challenge. This work aims to simulate potential MRI signatures combining arterial spin labeling (ASL) and multi-directional diffusion-weighted imaging (DWI). Driving our hypothesis are recent observations demonstrating a radial reorientation of microvasculature around the micro-infarction locus during recovery in mice. Synthetic capillary beds, randomly- and radially-oriented, and optical coherence tomography (OCT) angiograms, acquired in the barrel cortex of mice (n = 5) before and after inducing targeted photothrombosis, were analyzed. Computational vascular graphs combined with a 3D Monte-Carlo simulator were used to characterize the magnetic resonance (MR) response, encompassing the effects of magnetic field perturbations caused by deoxyhemoglobin, and the advection and diffusion of the nuclear spins. We quantified the minimal intravoxel signal loss ratio when applying multiple gradient directions, at varying sequence parameters with and without ASL. With ASL, our results demonstrate a significant difference (p < 0.05) between the signal-ratios computed at baseline and 3 weeks after photothrombosis. The statistical power further increased (p < 0.005) using angiograms measured at week 4. Without ASL, no reliable signal change was found. We found that higher ratios, and accordingly improved significance, were achieved at lower magnetic field strengths (e.g., B0 = 3T) and shorter echo time TE (< 16 ms). Our simulations suggest that microstrokes might be characterized through ASL-DWI sequence, providing necessary insights for posterior experimental validations, and ultimately, future translational trials.

scholarly journals Evaluating Coexistence of Fish Species with Coastal Cutthroat Trout in Low Order Streams of Western Oregon and Washington, USA

Fishes ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Kyle D. Martens ◽  
Jason Dunham
Keyword(s):  
Pacific Northwest ◽  
Species Interactions ◽  
Coho Salmon ◽  
Cutthroat Trout ◽  
Single Species ◽  
The Pacific ◽  
Small Streams ◽  
Coastal Cutthroat Trout ◽  
Multiple Species ◽  
Low Order

When multiple species of fish coexist there are a host of potential ways through which they may interact, yet there is often a strong focus on studies of single species without considering these interactions. For example, many studies of forestry–stream interactions in the Pacific Northwest have focused solely on the most prevalent species: Coastal cutthroat trout. To examine the potential for interactions of other fishes with coastal cutthroat trout, we conducted an analysis of 281 sites in low order streams located on Washington’s Olympic Peninsula and along the central Oregon coast. Coastal cutthroat trout and juvenile coho salmon were the most commonly found salmonid species within these streams and exhibited positive associations with each other for both presence and density. Steelhead were negatively associated with the presence of coastal cutthroat trout as well as with coho salmon and sculpins (Cottidae). Coastal cutthroat trout most frequently shared streams with juvenile coho salmon. For densities of these co-occurring species, associations between these two species were relatively weak compared to the strong influences of physical stream conditions (size and gradient), suggesting that physical conditions may have more of an influence on density than species interactions. Collectively, our analysis, along with a review of findings from prior field and laboratory studies, suggests that the net effect of interactions between coastal cutthroat trout and coho salmon do not appear to inhibit their presence or densities in small streams along the Pacific Northwest.

scholarly journals Conserving woodland caribou habitat while maintaining timber yield: a graph theory approach

2016 ◽  
Vol 46 (7) ◽  
pp. 914-923 ◽  
Author(s):  
Jonathan L.W. Ruppert ◽  
Marie-Josée Fortin ◽  
Eldon A. Gunn ◽  
David L. Martell
Keyword(s):  
Graph Theory ◽  
Rangifer Tarandus ◽  
High Volume ◽  
Timber Harvesting ◽  
Optimization Approach ◽  
Theory Approach ◽  
Heuristic Procedure ◽  
Woodland Caribou ◽  
Old Growth ◽  
Old Growth Forest

The fragmentation and loss of old-growth forest has led to the decline of many forest-dwelling species that depend on old-growth forest as habitat. Emblematic of this issue in many areas of the managed boreal forest in Canada is the threatened woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)). We develop a methodology to help determine when and how timber can be harvested to best satisfy both industrial timber supply and woodland caribou habitat requirements. To start, we use least-cost paths based on graph theory to determine the configuration of woodland caribou preferred habitat patches. We then developed a heuristic procedure to schedule timber harvesting based on a trade-off between merchantable wood volume and the remaining amount of habitat and its connectivity during a planning cycle. Our heuristic can attain 84% of the potential woodland caribou habitat that would be available in the absence of harvesting at the end of a 100 year planning horizon. Interestingly, this is more than that which is attained by the current plan (50%) and a harvesting plan that targets high volume stands (32%). Our results indicate that our heuristic procedure (i.e., an ecologically tuned optimization approach) may better direct industrial activities to improve old-growth habitat while maintaining specified timber production levels.

Using confidence intervals to estimate the response of salmon populations (Oncorhynchus spp.) to experimental habitat alterations

2005 ◽  
Vol 62 (12) ◽  
pp. 2716-2726 ◽  
Author(s):  
Michael J Bradford ◽  
Josh Korman ◽  
Paul S Higgins
Keyword(s):  
Confidence Intervals ◽  
Effect Size ◽  
Null Hypothesis ◽  
Statistical Power ◽  
Habitat Restoration ◽  
Coho Salmon ◽  
Fish Habitat ◽  
Monitoring Program ◽  
Considerable Uncertainty ◽  
Monitoring Programs

There is considerable uncertainty about the effectiveness of fish habitat restoration programs, and reliable monitoring programs are needed to evaluate them. Statistical power analysis based on traditional hypothesis tests are usually used for monitoring program design, but here we argue that effect size estimates and their associated confidence intervals are more informative because results can be compared with both the null hypothesis of no effect and effect sizes of interest, such as restoration goals. We used a stochastic simulation model to compare alternative monitoring strategies for a habitat alteration that would change the productivity and capacity of a coho salmon (Oncorhynchus kisutch) producing stream. Estimates of the effect size using a freshwater stock–recruit model were more precise than those from monitoring the abundance of either spawners or smolts. Less than ideal monitoring programs can produce ambiguous results, which are cases in which the confidence interval includes both the null hypothesis and the effect size of interest. Our model is a useful planning tool because it allows the evaluation of the utility of different types of monitoring data, which should stimulate discussion on how the results will ultimately inform decision-making.

Acclimation Improves Short-Term Survival of Hatchery Lahontan Cutthroat Trout in Water From Saline, Alkaline Walker Lake, Nevada

2010 ◽  
Vol 1 (2) ◽  
pp. 86-92 ◽  
Author(s):  
John P. Bigelow ◽  
Wendy M. Rauw ◽  
Luis Gomez-Raya
Keyword(s):  
Lake Water ◽  
Survival Rates ◽  
Fork Length ◽  
Cutthroat Trout ◽  
Ammonia Concentration ◽  
Walker Lake ◽  
Term Survival ◽  
Oncorhynchus Clarkii ◽  
Lahontan Cutthroat Trout ◽  
Tank Water

Abstract We investigated the effectiveness of two acclimation protocols for 8-month-old Lahontan cutthroat trout Oncorhynchus clarkii henshawi, reared at Lahontan National Fish Hatchery in terms of survival during a week-long challenge in water from saline, alkaline Walker Lake, Nevada. Fish were acclimated for 0 (control), 3, and 8 d by increasing the ratio of lake water to hatchery water. For the 3-d acclimation treatment, 50% of the tank water was replaced with lake water each day. For the 8-d treatment, 33% of the water was replaced with lake water on the first through fourth day of acclimation. Survival during acclimation (i.e., prior to the challenge) was lowest for fish acclimated 3 d. Median survival time during the lake water challenge was 8 h for unacclimated fish, and 8 and 12 h for fish surviving the 3- and 8-d acclimation treatments, respectively. No fish survived the entire week-long challenge. Compared with no acclimation, 3- and 8-d acclimation decreased the hazard of mortality during the challenge. Increased fork length also reduced the hazard of death. Our results indicate acceptable survival rates cannot be achieved for subyearling, hatchery-reared Lahontan cutthroat trout stocked in Walker Lake without acclimation or with the acclimation methods employed in this study. Our results indicate that the acclimation method might be improved by the use of longer fish, longer acclimation, and better control of water temperature, ammonia concentration, and alkalinity.

Experimental Management of Oregon Coho Salmon (Oncorhynchus kisutch): Designing for Yield of Information

1983 ◽  
Vol 40 (8) ◽  
pp. 1212-1223 ◽  
Author(s):  
Randall M. Peterman ◽  
Richard D. Routledge
Keyword(s):  
Statistical Power ◽  
Large Scale ◽  
Coho Salmon ◽  
Experimental Manipulation ◽  
Analytical Approximation ◽  
Large Variability ◽  
Power Of The Test ◽  
Marine Survival ◽  
Experimental Management ◽  
Experimental Release

Large-scale experimental manipulation of juvenile salmon (Oncorhynchus spp.) abundance can provide a test of the hypothesis of linearity in the smolt-to-adult abundance relation. However, not all manipulations will be equally informative owing to large variability in marine survival. We use Monte Carlo simulation and an analytical approximation to calculate for Oregon coho salmon (O. kisutch) the statistical power of the test involving different controlled smolt abundances and durations of experiments. One recently proposed experimental release of 48 million smolts for each of 3 yr has a relatively low power and, as a consequence, is unlikely to show clearly whether the smolt-to-adult relationship is linear. The number of smolts required for a powerful test of the hypothesis of linearity is closer to the 88 million suggested in another proposal. To prevent confounding of interpretation of results, all other human sources of variability in fish should be minimized by establishing standardized rearing and release procedures during the experiment. In addition, appropriate preexperiment data on coho food, predators, and competitors will increase effectiveness of experiments by providing information on mechanisms of change in marine survival.

Timber production versus old-growth preservation with endogenous prices and forest age-classes

2004 ◽  
Vol 34 (6) ◽  
pp. 1296-1310 ◽  
Author(s):  
Olli Tahvonen
Keyword(s):  
Environmental Values ◽  
Timber Harvesting ◽  
Timber Production ◽  
Forest Age ◽  
Forest Land ◽  
Age Classes ◽  
Old Growth ◽  
Class Distribution ◽  
Age Class ◽  
Long Run

This study combines timber production and environmental values, applying a dynamic forest-level economic model with any number of forest age-classes. The model includes endogenous timber price or nonlinear harvesting costs and various possibilities to specify the dependence of environmental values (related e.g. to species persistence) on the forest age-class structure. The nonlinearities in the net benefits from timber production have the consequence that fluctuations in optimal timber harvesting may totally vanish or at least become smaller than in forest scheduling models without ad hoc even flow constraints. If environmental values are specified to depend on the fraction of forest land preserved as old growth, the optimal long run allocation between timber production and old growth is represented by an equilibrium continuum. Thus the optimal long run allocation depends on the initial age-class distribution. The continuum and the dependence of initial age-class distribution vanish when the rate of discount approaches zero. If the environmental values of age-classes increase smoothly with age, the long run equilibrium may simultaneously include multiple rotation periods. The model determines the optimality of producing timber and environmental values separately at different parts of the forest or at the same piece of forest land. Numerical computation suggests that the optimal solution always converges toward some optimal long run stationary age-class distribution.

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