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Restoration practices aimed at fish habitat enhancement often include installation of instream structures. However, mixed outcomes have been reported regarding structure effectiveness, while mechanisms underlying success remain unclear. The interactions between fish and flow conditions generated by instream structures and their subsequent impact on fish energetics may provide some insight. This study seeks to quantify how restoration structures, simulated by cylinders in three orientations, alter the energetics and swimming stability of smallmouth bass (Micropterus dolomieu). Accelerometers measured swimming stability while a respirometer measured energy expenditure at multiple velocities. Particle image velocimetry was used to characterize flow fields behind structures. Structures generated flow conditions that benefited fish energetically. Fish had a smoother gait and expended less energy when swimming near a structure, regardless of its orientation. Benefits varied with flow conditions; reductions in energy expenditure were especially apparent at high flow velocities. Results suggest that restoration structures may be most energetically beneficial in stream systems with consistently high velocities and inform restoration by indicating flow conditions in which structures provide the greatest energetic benefits for fish. Les pratiques de restauration visant a ameliorer les habitats de poissons comprennent souvent l'amenagement d'ouvrages dans les cours d'eau. Des resultats mitiges ont toutefois ete rapportes quant a l'efficacite de tels ouvrages, et les mecanismes qui sous-tendent cette derniere demeurent mal compris. Les interactions entre les poissons et les conditions d'ecoulement produites par les ouvrages dans les cours d'eau et leur incidence subsequente sur l'energetique des poissons pourraient fournir des indices. L'etude tente de quantifier comment des ouvrages de restauration, simules par des cylindres de trois orientations differentes, modifient l'energetique et la stabilite de nage d'achigans a petite bouche (Micropterus dolomieu). Des accelerometres sont utilises pour mesurer la stabilite de nage et un respirometre, pour mesurer la depense energetique a differentes vitesses. La velocimetrie par images de particules est utilisee pour caracteriser les champs d'ecoulement en arriere des ouvrages. Ces derniers produisent des conditions d'ecoulement avantageuses pour les poissons sur le plan energetique. Les poissons nagent de maniere plus stable et depensent moins d'energie a proximite d'un ouvrage, peu importe son orientation. Les avantages varient selon les conditions d'ecoulement; des reductions de la depense energetique sont particulierement evidentes a de hautes vitesses d'ecoulement. Les resultats portent a croire que les ouvrages de restauration pourraient offrir les plus grands avantages sur le plan energetique dans les reseaux hydrographiques caracterises par des vitesses d'ecoulement uniformement elevees, et fournissent des renseignements utiles pour la restauration en indiquant les conditions d'ecoulement dans lesquelles ces ouvrages offrent aux poissons les plus grands avantages energetiques. [Traduit par la Redaction], Introduction Freshwater ecosystems worldwide are currently at risk due to anthropogenic degradation that imperils water quality, connectivity, and biodiversity (Gleick 2003; Dudgeon et al. 2006; Vorosmaity et al. 2010). The [...]

The potential benefits of physiology for conservation are well established and include greater specificity of management techniques, determination of cause-effect relationships, increased sensitivity of health and disturbance monitoring and greater capacity for predicting future change. While descriptions of the specific avenues in which conservation and physiology can be integrated are readily available and important to the continuing expansion of the discipline of 'conservation physiology', to date there has been no assessment of how the field has specifically contributed to conservation success. However, the goal of conservation physiology is to foster conservation solutions and it is therefore important to assess whether physiological approaches contribute to downstream conservation outcomes and management decisions. Here, we present eight areas of conservation concern, ranging from chemical contamination to invasive species to ecotourism, where physiological approaches have led to beneficial changes in human behaviour, management or policy. We also discuss the shared characteristics of these successes, identifying emerging themes in the discipline. Specifically, we conclude that conservation physiology: (i) goes beyond documenting change to provide solutions; (ii) offers a diversity of physiological metrics beyond glucocorticoids (stress hormones); (iii) includes approaches that are transferable among species, locations and times; (iv) simultaneously allows for human use and benefits to wildlife; and (v) is characterized by successes that can be difficult to find in the primary literature. Overall, we submit that the field of conservation physiology has a strong foundation of achievements characterized by a diversity of conservation issues, taxa, physiological traits, ecosystem types and spatial scales. We hope that these concrete successes will encourage the continued evolution and use of physiological tools within conservation-based research and management plans.

Heatwaves are becoming more frequent and intensified with climate change. Freshwater ecosystems are among the most threatened, within which, differing responses between cool- and warmwater species to heatwaves can lead to fundamental changes in communities. Physiological experiments can identify potential mechanisms underlying the impacts of such heatwaves on fish communities. In the current study, we quantified the oxygen consumption rate, aerobic scope and swimming performance of cool- and warmwater fish species following the simulation of short-term heatwaves currently occurring in streams in the Midwestern United States. The coolwater predator walleye (Sander vitreus) showed clear thermal disadvantages relative to the warmwater predator largemouth bass (Micropterus salmoides), based on a high metabolic cost during the heatwave, low metabolic activity when encountering prey, and reduced swimming performance following the heatwave. Largemouth bass also showed a thermal advantage relative to the warmwater prey fathead minnow (Pimephales promelas) related to swimming performance and energetic costs, highlighting differing thermal responses between predators and prey. This study demonstrates the importance of considering short-term extreme thermal events in the response of aquatic communities to climate stressors. [ABSTRACT FROM AUTHOR]

Reduced food availability increases the capture of several fish species, although the mechanisms responsible for how food resources result in increased capture are undefined. Our objective was to quantify the mechanism by which food availability might influence the angling vulnerability of muskellunge (Esox masquinongy). We assessed capture rates in the field under different food levels, quantified the behaviors of muskellunge that were either fed or food deprived, and determined if appetite‐related hormones leptin and ghrelin affected fish behavior. Catch rates of fasted muskellunge were more than twice as high as those of fed muskellunge. However, food deprivation and hormonal treatments did not influence laboratory behavior, which suggested that catch rates of food‐deprived muskellunge increased because fish were more receptive to lures. Furthermore, an ecosystem approach should be used to consider forage as a component of management goals. [ABSTRACT FROM AUTHOR]

Carbon dioxide (C[O.sub.2]) in water has been explored for use as an invasive species deterrent system. To date, studies have not determined C[O.sub.2] avoidance by fish in flowing water, and this is a necessary step before an operational deterrent system can be implemented. The objective of the study was to define how flowing water influences the response of bighead carp (Hypophthalmichthys nobilis) to continuous plugs of C[O.sub.2]. A choice experiment by which C[O.sub.2] was injected into channels of an annular flowing water flume was completed. In trials when C[O.sub.2] was injected into the inner vein, fish spent less time in the vein when compared with control conditions. An increased amount of lateral movements and reduced performance were also observed when fish were exposed to elevated C[O.sub.2]. The study demonstrates that bighead carp in flowing water enriched with C[O.sub.2] move away, a finding consistent with static water experiments. Le dioxyde de carbone (C[O.sub.2]) dans l'eau a ete etudie en vue de son utilisation comme systeme de dissuasion d'especes envahissantes. A ce jour, les etudes n'ont pas etabli s'il y a evitement du C[O.sub.2] par les poissons dans l'eau mouvante, bien qu'il s'agisse d'une etape prealable necessaire a la mise en reuvre de tout systeme de dissuasion. L'objectif de la presente etude etait d'etablir comment l'eau mouvante influence la reaction de carpes a grosse tete (Hypophthalmichthys nobilis) a des bouffees continues de C[O.sub.2]. Une experience de choix dans laquelle du C[O.sub.2] est injecte dans les chenaux d'un canal annulaire d'eau mouvante a ete realisee. Dans les essais, quand du C[O.sub.2] etait injecte dans la veine interieure, les poissons y passaient moins de temps que dans les conditions de reference. Plus de deplacements lateraux et une performance plus faible etaient aussi observes quand les poissons etaient exposes a des concentrations elevees de C[O.sub.2]. L'etude demontre que les carpes a grosse tete dans de l'eau mouvante enrichie en C[O.sub.2] s'en eloignent, une constatation qui concorde avec les resultats d'experiences en eau stationnaire. [Traduit par la Redaction], Introduction Aquatic invasive species (AIS) are prevalent across the planet, and management tools are often used to control their spread (Vander Zanden and Olden 2008). Specifically, for freshwater fish, unfettered [...]

Near‐future climate change projections predict an increase in sea surface temperature that is expected to have significant and rapid effects on marine ectotherms, potentially affecting a number of critical life processes. Some habitats also undergo more thermal variability than others, and the inhabitants therefore must be more tolerant to acute periods of extreme temperatures. Mitigation of these outcomes may occur through acclimation, plasticity or adaptation, although the rate and extent of a species' ability to adjust to warmer temperatures is largely unknown, specifically as it pertains to effects on various performance metrics in fishes that inhabit multiple habitats throughout ontogenetic stages. Here, the thermal tolerance and aerobic performance of schoolmaster snapper (Lutjanus apodus Walbaum, 1792) collected from two different habitats were experimentally assessed under different warming scenarios (temperature treatments = 30, 33, 35, 36°C) to assess vulnerability to an imminently changing thermal habitat. Larger subadult and adult fish collected from a 12 m deep coral reef exhibited a lower critical thermal maximum (CTmax) compared to smaller juvenile fish collected from a 1 m deep mangrove creek. However, the CTmax of the creek‐sampled fish was only 2°C above the maximum water temperature measured in the habitat from which they were collected, compared to a CTmax that was 8°C higher in the reef‐sampled fish, resulting in a wider thermal safety margin at the reef site. A generalized linear model showed a marginally significant effect of temperature treatment on resting metabolic rate (RMR), but there were no effects of any of the tested factors on maximum metabolic rate or absolute aerobic scope. Post hoc tests revealed that RMR was significantly higher for creek‐collected fish at the 36°C treatment and significantly higher for reef‐collected fish at 35°C. Swimming performance [measured by critical swimming speed] was significantly lower at the highest temperature treatment for creek‐collected fish and trended down with each successive increase in temperature treatment for reef‐collected fish. These results show that metabolic rate and swimming performance responses to thermal challenges are somewhat consistent across collection habitats, and this species may be susceptible to unique types of thermal risk depending on its habitat. We show the importance of intraspecific studies that couple habitat profiles and performance metrics to better understand possible outcomes under thermal stress. [ABSTRACT FROM AUTHOR]

Zones of elevated carbon dioxide (C[O.sub.2]) have the potential to deter the movement of fishes. Should C[O.sub.2] be used as a barrier, non-target organisms, such as freshwater mussels, have the potential to be impacted. In this study, the physiological responses of adult Fusconaia flava exposed to elevated partial pressures of C[O.sub.2] (pC[O.sub.2]) over both short-term (6 h exposure with 6 h recovery) and long-term (4-, 8-, and 32-day exposure) periods were measured. A 6 h exposure to either ~15 000 µatm (1 atm = 101.325 kPa) or ~200 000 µatm caused an elevation in hemolymph [Ca.sup.2+]. Exposure to ~200 000 µatm resulted in a decrease in hemolymph [Cl.sup.-], and exposure to ~15 000 µatm caused an increase in hemolymph [Na.sup.+], whereas ~200 000 µatm caused a decrease. Exposure to elevated pC[O.sub.2] for long-term periods caused a decrease in hemolymph [Mg.sup.2+] and an initial increase in hemolymph [Ca.sup.2+]. Body condition and hemolymph glucose were not significantly influenced by elevated pC[O.sub.2] for both experiments. This study shows that elevated pC[O.sub.2] had limited impacts on the physiological responses of adult freshwater mussels. Les zones de concentrations elevees de dioxyde de carbone (C[O.sub.2]) pourraient faire entrave aux deplacements de poissons. L'utilisation eventuelle du C[O.sub.2] comme barriere pourrait avoir un impact sur des organismes non cibles, comme les moules d'eau douce. Nous avons mesure les reactions physiologiques de fusconaias jaunes (Fusconaiaflava) adultes exposees a des pressions partielles de C[O.sub.2] (pC[O.sub.2]) elevees pendant de courtes (exposition de 6 heures avec recuperation de 6 heures) et longues durees (expositions de 4, 8 et 32 jours). Une exposition de 6 heures a des pC[O.sub.2] de ~15 000 µatm (1 atm = 101.325 kPa) ou ~200 000 µatm entrainait une hausse du [Ca.sup.2+] hemolymphatique. Une exposition a ~200 000 µatm se traduisait par une baisse du [Cl.sup.-] hemolymphatique et une exposition a ~15 000 µatm entrainait une hausse du [Na.sup.+] hemolymphatique, alors qu'une exposition a ~200 000 µatm entrainait sa baisse. L'exposition a de fortes pC[O.sub.2] pendant de longues periodes causait une baisse du [Mg.sup.2+] hemolymphatique et une baisse initiale du [Ca.sup.2+] hemolymphatique. Dans les deux experiences, des pC[O.sub.2] elevees n'ont pas eu d'influence significative sur l'embonpoint et le glucose hemolymphatique. L'etude demontre que de fortes pC[O.sub.2] ont des effets limites sur les reactions physiologiques des moules d'eau douce adultes. [Traduit par la Redaction], Introduction The introduction of non-native species can have long-lasting impacts on resident populations and 'invaded' environments (Pimentel et al. 2005; Ricciardi et al. 2013). Many invaders have been concentrated in [...]