Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

This is an open access article. You can find it online by following this link: http://www.esajournals.org/doi/pdf/10.1890/ES13-00269.1An experiment and a mark-recapture field study of juvenile coho salmon (Oncorhynchus kisutch) were conducted to identify controls of key energy flow chains in river food webs. In the small-scale experiment, we investigated the individual and interactive effects of physical habitat structure (PHS) as small wood and resource availability (tissue of adult Chinook salmon, O. tshawytscha) on nutrients, algae, invertebrates, and fish predators including juvenile coho. In the field, we quantified the effects of natural variation in prey availability (invertebrate drift biomass), PHS (wood), and local fish density on summer growth of juvenile coho across multiple stream reaches. Adding salmon tissue to experimental channels resulted in strong bottom-up effects on select invertebrates including increased population biomass of chironomids and baetids, the numerically dominant invertebrates, and faster growth of juvenile coho. We link the enhanced growth of coho to chironomid productivity: for instance, adult chironomid flux was 4.33 higher and coho consumption of these animals 33 higher in salmon-subsidized channels. PHS in experimental channels was associated with reduced algal biomass, potentially in response to increased invertebrate consumption, and invertebrate flux or export. The field study revealed coho growth was negatively related to PHS and total fish density and positively related to Diptera drift biomass; however, the effects of fish density and drift biomass on coho growth were relatively weak. The field study also indicated that prey resource availability and coho growth were associated with differences in canopy cover, with prey biomass and coho growth 2–43higher in reaches receiving more sunlight. As in the experiment, coho in natural stream reaches predominantly fed on adult chironomids and other Diptera, indicating that these taxa and life-stages are a key link between the benthic food web and mobile vertebrate predators. Our study showed that bottom-up processes initiated by salmon subsidies and possibly light flux determined key trophic interactions in the Cedar River food web. Moreover, we speculate that PHS may modify some of these interactions indirectly through its effects on the movement of organisms through the environment

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

An experiment and a mark-recapture field study of juvenile coho salmon ( Oncorhynchus kisutch ) were conducted to identify controls of key energy flow chains in river food webs. In the small-scale experiment, we investigated the individual and interactive effects of physical habitat structure (PHS) as small wood and resource availability (tissue of adult Chinook salmon, O. tshawytscha ) on nutrients, algae, invertebrates, and fish predators including juvenile coho. In the field, we quantified the effects of natural variation in prey availability (invertebrate drift biomass), PHS (wood), and local fish density on summer growth of juvenile coho across multiple stream reaches. Adding salmon tissue to experimental channels resulted in strong bottom-up effects on select invertebrates including increased population biomass of chironomids and baetids, the numerically dominant invertebrates, and faster growth of juvenile coho. We link the enhanced growth of coho to chironomid productivity: for instance, adult chironomid flux was 4.3 3 higher and coho consumption of these animals 3 3 higher in salmon-subsidized channels. PHS in experimental channels was associated with reduced algal biomass, potentially in response to increased invertebrate consumption, and invertebrate flux or export. The field study revealed coho growth was negatively related to PHS and total fish density and positively related to Diptera drift biomass; however, the effects of fish density and drift biomass on coho growth were relatively weak. The field study also indicated that prey resource availability and coho growth were associated with differences in canopy cover, with prey biomass and coho growth 2–4 3 higher in reaches receiving more sunlight. As in the experiment, coho in natural stream reaches predominantly fed on adult chironomids and other Diptera, indicating that these taxa and life-stages are a key link between the benthic food web and mobile vertebrate predators. Our study showed that bottom-up processes initiated by salmon subsidies and possibly light flux determined key trophic interactions in the Cedar River food web. Moreover, we speculate that PHS may modify some of these interactions indirectly through its effects on the movement of organisms through the environment

Abundance and body condition of sculpin (Cottus spp.) in a small forest stream following recolonization by juvenile Coho Salmon (Oncorynchus kisutch)

Recolonization by native species following reintroduction can affect resident species through a variety of processes. We examined the effects of natural recolonization by coho salmon Oncorhynchus kisutch on sculpin (Cottus rhotus and Cottus gulosus), small benthic fishes, in a small forest stream in Western Washington, USA. Provision fish passage around a small dam allowed coho access to habitat, which had been inaccessible for over 100 years. We found that density (g m−2 and number m−2) was unchanged, and body condition (the slope of the relationship between length and weight) of sculpin tended to increase from before relative to a 5-year period following recolonization. The proportion of sculpin comprising the total fish assemblage decreased after coho colonization relative to before but remained stable for a 5-year period after coho reintroduction, whereas coho density increased over fivefold. Additionally, we used Akaike's information criteria to evaluate the relative importance of physical and biological variables to predict sculpin density in pool habitats during the initial coho recolonization period. Physical microhabitat variables had little support for predicting sculpin density, whereas there was a significant support for stream temperature; cutthroat trout (Oncorhynchus clarkii) density and year were the most important predictors of sculpin density. Coho density was not significant in any model. Our results indicate coho introduction and subsequent recolonization have to date had minimal individual or population level effects on sculpin, therefore demonstrating that species reintroductions into their native range can have no measurable effect on resident organisms. Published 2013. This article is a U.S. Government work and is in the public domain in the USA

CALAGEM E ADUBA\uc7\uc3O FOSFATADA NO CRESCIMENTO DE MUDAS DE Mimosa caesalpiniifolia Benth. EM LATOSSOLO VERMELHO-AMARELO

This work aimed to evaluate the effects of liming and phosphate fertilizer for the production of sabi\ue1 ( Mimosa caesalpiniifolia Benth.) seedlings without thorns under a greenhouse. Seedlings 10 days old were transferred to plastic bags containing 2.0 kg of psamitic Dystrophic Red-Yellow Latosol (Typic Haplustox) collected from 40 to 70 cm layer. The experiment was carried out in Teresina county, Piau\ued state, Brazil, from July to October of 2008. Two liming doses (with and without liming) and five phosphorus doses combined in a 2 x 5 factorial scheme were used. The experimental design used was the randomized blocks with four replications having each plot three seedlings. The calculated lime amount was enough to elevate the base saturation to 50 % and the phosphorus doses were: 0, 30, 60, 90, and 120 mg kg-1 of soil. One seedling per pot was cultivated and the pot dimension was 10 by 23 cm. The evaluated variables were height, diameter, leaves number, leaf area, and shoot and roots dry matter. For the studied soil condition, the liming is not necessary to produce 'Sabi\ue1' seedlings. The application, on average, from 72 to 107 mg kg-1 of P promote, respectively, from 90 to100 % of maximum values of height, diameter, leaf area and shoots and roots biomass.O presente trabalho teve por objetivo avaliar os efeitos da adi\ue7\ue3o de calc\ue1rio e adubo fosfatado na produ\ue7\ue3o de mudas de sabi\ue1 ( Mimosa caesalpiniifolia Benth.) sem ac\ufaleos, em ambiente protegido. Pl\ue2ntulas com 10 dias de idade foram transferidas para sacos de pl\ue1stico contendo 2,0 kg de Latossolo Vermelho-Amarelo distr\uf3fico psam\uedtico, coletado na camada de 40 a 70 cm. O experimento foi conduzido no munic\uedpio de Teresina \u2013 PI, no per\uedodo de julho a outubro de 2008, em ambiente protegido por tela com 50 % de reten\ue7\ue3o de luz. Foram usadas duas doses de calc\ue1rio (com e sem calc\ue1rio) e cinco doses de f\uf3sforo, combinadas em esquema fatorial 2 x 5. O delineamento experimental foi em blocos ao acaso com quatro repeti\ue7\uf5es e cada parcela continha tr\ueas mudas. A quantidade de calc\ue1rio foi calculada para elevar a satura\ue7\ue3o por bases a 50 % com o uso de calc\ue1rio e as doses de f\uf3sforo foram 0, 30, 60, 90 e 120 mg kg-1 de P. Foi cultivada uma muda por saco de pl\ue1stico, com as dimens\uf5es de 10 x 23 cm. As vari\ue1veis avaliadas nas mudas foram: altura, di\ue2metro a 1,0 cm do coleto, \ue1rea foliar, n\ufamero de folhas e mat\ue9ria seca da parte a\ue9rea e ra\uedzes. Nas condi\ue7\uf5es do solo estudado, a calagem n\ue3o \ue9 necess\ue1ria para produ\ue7\ue3o de mudas de sabi\ue1. A aplica\ue7\ue3o de, em m\ue9dia, 72 a 107 mg kg-1 de P obt\ue9m-se, respectivamente, de 90 a 100 % dos m\ue1ximos rendimentos de altura, di\ue2metro, \ue1rea foliar, biomassa da parte a\ue9rea e ra\uedze

CALAGEM E ADUBA\uc7\uc3O FOSFATADA NO CRESCIMENTO DE MUDAS DE Mimosa caesalpiniifolia Benth. EM LATOSSOLO VERMELHO-AMARELO

This work aimed to evaluate the effects of liming and phosphate fertilizer for the production of sabi\ue1 ( Mimosa caesalpiniifolia Benth.) seedlings without thorns under a greenhouse. Seedlings 10 days old were transferred to plastic bags containing 2.0 kg of psamitic Dystrophic Red-Yellow Latosol (Typic Haplustox) collected from 40 to 70 cm layer. The experiment was carried out in Teresina county, Piau\ued state, Brazil, from July to October of 2008. Two liming doses (with and without liming) and five phosphorus doses combined in a 2 x 5 factorial scheme were used. The experimental design used was the randomized blocks with four replications having each plot three seedlings. The calculated lime amount was enough to elevate the base saturation to 50 % and the phosphorus doses were: 0, 30, 60, 90, and 120 mg kg-1 of soil. One seedling per pot was cultivated and the pot dimension was 10 by 23 cm. The evaluated variables were height, diameter, leaves number, leaf area, and shoot and roots dry matter. For the studied soil condition, the liming is not necessary to produce 'Sabi\ue1' seedlings. The application, on average, from 72 to 107 mg kg-1 of P promote, respectively, from 90 to100 % of maximum values of height, diameter, leaf area and shoots and roots biomass.O presente trabalho teve por objetivo avaliar os efeitos da adi\ue7\ue3o de calc\ue1rio e adubo fosfatado na produ\ue7\ue3o de mudas de sabi\ue1 ( Mimosa caesalpiniifolia Benth.) sem ac\ufaleos, em ambiente protegido. Pl\ue2ntulas com 10 dias de idade foram transferidas para sacos de pl\ue1stico contendo 2,0 kg de Latossolo Vermelho-Amarelo distr\uf3fico psam\uedtico, coletado na camada de 40 a 70 cm. O experimento foi conduzido no munic\uedpio de Teresina - PI, no per\uedodo de julho a outubro de 2008, em ambiente protegido por tela com 50 % de reten\ue7\ue3o de luz. Foram usadas duas doses de calc\ue1rio (com e sem calc\ue1rio) e cinco doses de f\uf3sforo, combinadas em esquema fatorial 2 x 5. O delineamento experimental foi em blocos ao acaso com quatro repeti\ue7\uf5es e cada parcela continha tr\ueas mudas. A quantidade de calc\ue1rio foi calculada para elevar a satura\ue7\ue3o por bases a 50 % com o uso de calc\ue1rio e as doses de f\uf3sforo foram 0, 30, 60, 90 e 120 mg kg-1 de P. Foi cultivada uma muda por saco de pl\ue1stico, com as dimens\uf5es de 10 x 23 cm. As vari\ue1veis avaliadas nas mudas foram: altura, di\ue2metro a 1,0 cm do coleto, \ue1rea foliar, n\ufamero de folhas e mat\ue9ria seca da parte a\ue9rea e ra\uedzes. Nas condi\ue7\uf5es do solo estudado, a calagem n\ue3o \ue9 necess\ue1ria para produ\ue7\ue3o de mudas de sabi\ue1. A aplica\ue7\ue3o de, em m\ue9dia, 72 a 107 mg kg-1 de P obt\ue9m-se, respectivamente, de 90 a 100 % dos m\ue1ximos rendimentos de altura, di\ue2metro, \ue1rea foliar, biomassa da parte a\ue9rea e ra\uedzes

Potential for ecological nonlinearities and thresholds to inform Pacific salmon management

AbstractEcology is often governed by nonlinear dynamics. Nonlinear ecological relationships can include thresholds—incremental changes in drivers that provoke disproportionately large ecological responses. Among the species that experience nonlinear and threshold dynamics are Pacific salmon (Oncorhynchus spp.). These culturally, ecologically, and economically significant fishes are in many places declining and management focal points. Often, managers can influence or react to ecological conditions that salmon experience, suggesting that nonlinearities, especially thresholds, may provide opportunities to inform decisions. However, nonlinear dynamics are not always invoked in management decisions involving salmon. Here, we review reported nonlinearities and thresholds in salmon ecology, describe potential applications that scientists and managers could develop to leverage nonlinear dynamics, and offer a path toward decisions that account for ecological nonlinearities and thresholds to improve salmon outcomes. It appears that nonlinear dynamics are not uncommon in salmon ecology and that many management arenas may potentially leverage them to enable more effective or efficient decisions. Indeed, decisions guided by nonlinearities and thresholds may be particularly desirable considering salmon management arenas are often characterized by limited resources and mounting ecological stressors, practical constraints, and conservation challenges. More broadly, many salmon systems are data‐rich and there are an extensive range of ecological contexts in which salmon are sensitive to anthropogenic decisions. Approaches developed to leverage nonlinearities in salmon ecology may serve as examples that may inform analogous approaches in other systems and taxa

Lessons from Elwha Ecosystem Restoration: Integrating science, policy, and management

After decades of debate, planning, and environmental impact studies, the largest planned dam removal project in history was conducted on the Elwha River in Washington State, USA, from 2011 to 2014. Because this was such a unique and unprecedented project, the planning, implementation, and monitoring has occurred over 30 years and required diverse expertise across multiple stakeholders. This knowledge portfolio required that individuals and organizations with different missions collaborate effectively to ensure a successful project. The story of this river, with rugged headwaters, protected wilderness, legendary and culturally important salmon runs, and two hydroelectric dams whose placement marshaled wholesale socioeconomic and ecological changes, has become an iconic saga of change, perseverance and renewal. The two dams blocked fish migrations and disrupted sediment transport for a century, disrupting the ecological structure and function of the Elwha River. Removal of the 64-m and 32-m tall dams and the release of a large portion of the 21 million cubic meters of stored reservoir sediment, has provided a living laboratory to study the patterns, processes and outcomes of dam removal across freshwater, estuarine, and marine ecosystem boundaries from multiple scientific perspectives. This collaborative multidisciplinary approach has allowed us to improve our understanding of ecosystem responses and linkages while making the Elwha River one of the best studied dam removal projects

Optimization of culture conditions for exopolysaccharides production in Rhizobium sp. using the response surface method

The combined effects of the processing parameters for exopolysaccharides production by Rhizobium sp. was studied using the experimental design and response surface methodology. The experiments were carried out using a fermenter with 20 L capacity, as the reactor. All processing parameters were online monitored. The temperature [(30 \ub1 1)\ub0C] and pH value (7.0 \ub1 0.1) were kept constant throughout the experimental time. As statistical tools, a complete 23 factorial planning with central point and response surface were used to study the interactions among three relevant variables of the fermentation process: calcium carbonate concentration, aeration and agitation. The processing parameters setup for reaching a maximum response for exopolysaccharides production was obtained when applying the highest values for calcium carbonate concentration (1.1 g/L), aeration (1.3 vvm) and agitation (800 rpm). In addition, the combination of these optimum processing parameters yielded YP/S (g/g) = 0.35

Bifurcations in annular electroconvection with an imposed shear

We report an experimental study of the primary bifurcation in electrically-driven convection in a freely suspended film. A weakly conducting, submicron thick smectic liquid crystal film was supported by concentric circular electrodes. It electroconvected when a sufficiently large voltage $V$ was applied between its inner and outer edges. The film could sustain rapid flows and yet remain strictly two-dimensional. By rotation of the inner electrode, a circular Couette shear could be independently imposed. The control parameters were a dimensionless number ${\cal R}$, analogous to the Rayleigh number, which is $\propto V^2$ and the Reynolds number ${\cal R}e$ of the azimuthal shear flow. The geometrical and material properties of the film were characterized by the radius ratio $\alpha$, and a Prandtl-like number ${\cal P}$. Using measurements of current-voltage characteristics of a large number of films, we examined the onset of electroconvection over a broad range of $\alpha$, ${\cal P}$ and ${\cal R}e$. We compared this data quantitatively to the results of linear stability theory. This could be done with essentially no adjustable parameters. The current-voltage data above onset were then used to infer the amplitude of electroconvection in the weakly nonlinear regime by fitting them to a steady-state amplitude equation of the Landau form. We show how the primary bifurcation can be tuned between supercritical and subcritical by changing $\alpha$ and ${\cal R}e$.Comment: 17 pages, 12 figures. Submitted to Phys. Rev. E. Minor changes after refereeing. See also http://mobydick.physics.utoronto.c