Tolerance to Hypercarbia Is Repeatable and Related to a Component of the Metabolic Phenotype in a Freshwater Fish

Freshwater fish may be exposed to high levels of carbon dioxide (CO2) because of several actions, including anesthesia and high levels of aquatic respiration and potentially as the result of using high-CO2 plumes as a barrier to the movements of invasive fishes. Metabolic phenotype can potentially drive how freshwater fish respond to high CO2. We therefore quantified how tolerance (measured using time to equilibrium loss [ELT]) was driven by metabolic phenotype in a cosmopolitan freshwater fish species, Micropterus salmoides. ELT was repeatable, with 60% of the variance across trials attributable to individual differences. For each fish, standard metabolic rate and maximum metabolic rate were measured using respirometers and time to exhaustion after a chase test was recorded. Fish with high anaerobic performance were less tolerant to elevated CO2, potentially as a result of preexisting metabolic acidosis. Standard metabolic rate and aerobic scope did not predict ELT. Our findings define which fish may be more vulnerable to high CO2, a potential mechanism for this tolerance, and show that tolerance to high CO2 may be acted on by natural selection. Should freshwater ecosystems become elevated in CO2, by either natural means or anthropogenic means, it is possible that there is potential for heritable selection of CO2 tolerance, evidenced by the fact that ELT was found to be repeatable."The study was supported by Illinois Department of Natural Resources (CAFWS-93) and the US Geological Survey, through funds provided to C.D.S. by the Great Lakes Restoration Initiative (G14AC00119)."https://www.journals.uchicago.edu/doi/abs/10.1086/69337

Physiological responses of three species of unionid mussels to intermittent exposure to elevated carbon dioxide

Freshwater systems are at risk owing to increasing carbon dioxide (CO2) levels, and one of the possible reasons for these elevations is the deployment of non-physical fish barriers to prevent invasive fish movements. Carbon dioxide barriers have the potential to create short, chronic and intermittent exposures of CO2 for surrounding freshwater biota. Although intermittent exposures to a stressor may be more ecologically relevant, the majority of laboratory tests use chronic or short-term time periods to determine how organisms will respond to an environmental stressor. Measurements of the physiological responses of three species of unionid mussel, giant floaters (Pyganodon grandis), threeridge (Amblema plicata) and plain pocketbook (Lampsilis cardium), exposed to control pCO2 (~1000 μatm) or intermittent conditions of pCO2 (ranging from ~1000 to ~55 000 μatm) 12 times per day over a 28 day period were gathered. There was no indication of recovery in the physiological responses of mussels between applications of CO2, suggesting that the recovery time between CO2 pulses (1.5 h) was not sufficient for recovery from the CO2 exposure period (0.5 h). Observations of acid–base and stress responses were consistent with what has been observed in chronic studies of freshwater mussels exposed to elevated pCO2 (i.e. elevations in HCO3−, Ca2+, Na+ and glucose, and decreases in Mg2+ and Cl−). However, species differences were observed across almost all variables measured, which emphasizes the need for multispecies studies."This work was supported by the Illinois Department of Natural Resources and the United States Geological Survey, through funds provided by the United States Environmental Protection Agency’s Great Lakes Restoration Initiative."https://academic.oup.com/conphys/article/4/1/cow066/275336

Spatial ecology of adult muskellunge (Esox masquinongy) in the urban Ottawa reach of the historic Rideau Canal, Canada

The Rideau Canal in Canada was constructed in the 1800s to enable strategic military and commercial transport in eastern Ontario between Lake Ontario and the Ottawa River. Today, the Rideau Canal is managed by Parks Canada and remains an engineered ecosystem, particularly in the urban Ottawa reach (7 km long) where it is largely channelized and is partially drained during the winter to protect canal infrastructure (i.e., locks) and provide recreational opportunities (i.e., skating). Interestingly, the Ottawa reach of the Rideau Canal supports one of the few wild urban muskellunge (Esox masquinongy) fisheries in North America supported by natural reproduction. However, little is known about the spatial ecology, residency patterns or survival of this apex freshwater predator in urban environments or canal systems. Radio-telemetry was used to study adult (N = 10; total size range of 64 to 122 cm) muskellunge in the Ottawa reach of the Rideau Canal over a multiple year period. The seasonal movements and home range of muskellunge were greatest during spring corresponding with the period when water levels in the canal were raised and muskellunge were presumably seeking out suitable spawning habitats following ice-off. During the summer fish ranged throughout the entire 7 km urban reach of the canal and by early fall muskellunge moved to the deeper parts of the reach and became largely restricted to an embayment known as Dow’s Lake prior to the lowering of the canal where they stayed for the entire winter. The same pattern of seasonal movements persisted across several years. None of the tagged muskellunge were stranded from the fall canal drainage. One fish emigrated from the urban reach of the canal during the study period, moving upstream through a lock to an exurban reach. In addition, a single tagged fish died from a winterkill event. Environmental influences such as seasonality and water depth (associated with canal operations) are believed to be the primary mechanisms contributing to habitat selection and movement patterns of muskellunge in this reach of the Rideau Canal. Data on the spatial ecology of muskellunge in the urban reaches of the Rideau Canal will inform management of this unique population of fish to ensure that the historic and ecological values are balanced to preserve this iconic Canadian natural heritage site and its biota."The authors would like to thank the Ottawa Chapter of Muskies Canada for the funding and field assistance provided during this study."https://www.alr-journal.org/articles/alr/abs/2010/02/alr012-10/alr012-10.htm

Chill out: physiological responses to winter ice-angling in two temperate freshwater fishes

A large body of research has documented the stress response of fish following angling capture. Nearly all of these studies have taken place during the open-water season, with almost no work focused on the effects of capture in the winter via ice angling. We therefore conducted a study to examine physiological disturbance and reflex impairment following capture by ice-angling in two commonly targeted species, bluegill Lepomis macrochirus and yellow perch Perca flavescens. Fish were captured from a lake in eastern Wisconsin (USA) and sampled either immediately or after being held in tanks for 0.5, 2 or 4 h. Sampling involved the assessment of reflex action mortality predictors (RAMP) and a blood biopsy that was used to measure concentrations of plasma cortisol and lactate. The capture-induced increase in plasma cortisol concentration was delayed relative to responses documented in previous experiments conducted in the summer and reached a relative high point at 4 h post-capture. Reflex impairment was highest at the first post-capture time point (0.5 h) and declined with each successive sampling (2 and 4 h) during recovery. Bluegill showed a higher magnitude stress response than yellow perch in terms of plasma cortisol and RAMP scores, but not when comparing plasma lactate. Overall, these data show that ice-angling induces a comparatively mild stress response relative to that found in previous studies of angled fish. While recovery of plasma stress indicators does not occur within 4 h, declining RAMP scores demonstrate that ice-angled bluegill and yellow perch do recover vitality following capture."This work was supported by Federal Aid in Sport Fish Restoration Project F-69-R-29 to J.A.S."https://academic.oup.com/conphys/article/5/1/cox027/376958

Injecting youth into peer-review to increase its sustainability: a case study of ecology journals

The "tragedy of the reviewer commons", where the referee pool is being drained by an influx of manuscript submissions, is becoming an increasing problem for journals. To mitigate this growing concern, we suggest that there is a need to inject youth into the peer-review process. Graduate students, post-docs, and junior researchers are an important, yet often underutilized resource, for the peer-review process. A survey of leading ecology journals revealed that editors are generally receptive to increasing the involvement of junior referees in the peer-review process. Through 45 responses to the survey, no journal had specific policies regarding junior referees or maintained databases specifically identifying junior reviewers, and only 34% of respondents actively solicited junior referees. Despite this level of utilization, editors generally feel that junior referees have expertise in specific subject areas, are keen to review, and are willing to make time to provide a high-quality review, particularly when aided by their supervisors. Editors were significantly more likely to select junior referees with higher levels of education and experience (e.g., 90% of respondents were highly likely to select a post-doctoral researcher to conduct a review), although editors were willing to consider graduate students as well. Integrating and expanding on these survey results, we argue that injecting youth into peer-review benefits the process and provides invaluable experience and insight to junior scholars, all while helping to mitigate the problem of the tragedy of the reviewer commons.https://ojs.library.queensu.ca/index.php/IEE/article/view/234

Population size and spatial ecology of Blanding’s turtle (Emydoidea blandingii) in South March Highlands, Ottawa, Canada

Between 2010–2011, an arterial road was constructed within provincially significant wetlands in the South March Highlands (SMH) located in Ottawa, Ontario, Canada. The wetlands and adjacent upland areas were determined to be sensitive habitat for Blanding’s turtles (Emydoidea blandingii (Holbrook, 1838)) during the approval and permitting process and a population study was required as part of the road construction project. The study consisted of a four-year mark-and-recapture program and a movement study of radio-tagged adult turtles. General findings included the identification of 27 adult males and 55 females and a population estimate of 93 adults (95 % Cl; 86–118). A 1:2.32 male to female sex bias was also found. Mean home range size was 19.06 ha and tagged turtles moved on average more per observation in 2013 (191.40 m compared to 89.75 m and 123.04 m in 2011 and 2012, respectively). Previously reported differences in movement patterns between males, females, and gravid females were not observed. The SMH Blanding’s turtle population should be closely monitored as urban development continues in the area, which may further reduce the population size. Understanding the biology of imperiled populations across species ranges is necessary to promote conservation and adaptive wildlife management.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Tolerance to Hypercarbia is repeatable and related to a component of the metabolic phenotype in a freshwater fish

Freshwater fish may be exposed to high levels of carbon dioxide (CO2) because of several actions, including anesthesia and high levels of aquatic respiration and potentially as the result of using high-CO2 plumes as a barrier to the movements of invasive fishes. Metabolic phenotype can potentially drive how freshwater fish respond to high CO2. We therefore quantified how tolerance (measured using time to equilibrium loss [ELT]) was driven by metabolic phenotype in a cosmopolitan freshwater fish species, Micropterus salmoides. ELT was repeatable, with 60% of the variance across trials attributable to individual differences. For each fish, standard metabolic rate and maximum metabolic rate were measured using respirometers and time to exhaustion after a chase test was recorded. Fish with high anaerobic performance were less tolerant to elevated CO2, potentially as a result of preexisting metabolic acidosis. Standard metabolic rate and aerobic scope did not predict ELT. Our findings define which fish may be more vulnerable to high CO2, a potential mechanism for this tolerance, and show that tolerance to high CO2 may be acted on by natural selection. Should freshwater ecosystems become elevated in CO2, by either natural means or anthropogenic means, it is possible that there is potential for heritable selection of CO2 tolerance, evidenced by the fact that ELT was found to be repeatable

Chronic exposure of a freshwater mussel to elevated pCO(2): effects on the control of biomineralization and ion-regulatory responses

Freshwater mussels may be exposed to elevations in mean partial pressure of carbon dioxide (pCO(2)) caused by both natural and anthropogenic factors. The goal of the present study was to assess the effects of a 28-d elevation in pCO(2) at 15 000 and 50 000 mu atm on processes associated with biomineralization, ion regulation, and cellular stress in adult Lampsilis siliquoidea (Barnes, 1823). In addition, the capacity for mussels to compensate for acid-base disturbances experienced after exposure to elevated pCO(2) was assessed over a 14-d recovery period. Overall, exposure to 50 000 mu atm pCO(2) had more pronounced physiological consequences compared with 15 000 mu atm pCO(2). Over the first 7 d of exposure to 50 000 mu atm pCO(2), the mRNA abundance of chitin synthase (cs), calmodulin (cam), and calmodulin-like protein (calp) were significantly affected, suggesting that shell formation and integrity may be altered during pCO(2) exposure. After the removal of the pCO(2) treatment, mussels may compensate for the acid-base and ion disturbances experienced during pCO(2) exposure, and transcript levels of some regulators of biomineralization (carbonic anhydrase [ca], cs, cam, calp) as well as ion regulation (na(+)-k(+)-adenosine triphosphatase [nka]) were modulated. Effects of elevated pCO(2) on heat shock protein 70 (hsp70) were limited in the present study. Overall, adult L. siliquoidea appeared to regulate factors associated with the control of biomineralization and ion regulation during and/or after the removal of pCO(2) exposure