Article

Responses of native and invasive fishes to carbon dioxide: Potential for a nonphysical barrier to fish dispersal

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Abstract

Upon arrival in a novel environment, invasive species have the potential to cause negative consequences at their new location. Rather than try to eliminate invasive species after introduction, preventing their spread is a more efficient strategy to mitigate impact. The current study used a laboratory setting to quantify the efficacy of elevated carbon dioxide (CO2) in water to act as a nonphysical barrier to deter fish movement. Our focus was on deterring the movements of silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis), but largemouth bass (Micropterus salmoides) and bluegill (Lepomis macrochirus) were also examined to quantify the impact of elevated CO2 on native species. Exposure of all species to 30 mg.L-1 dissolved CO2 for 1 h, compared with ambient CO2 concentrations of 10 mg.L-1, resulted in an elevated stress response, along with alterations to ionic-osmotic balance. Exposure of fish to 70 mg.L-1 CO2 caused a reduction in ventilation rates after 1 h, while both silver carp and bighead carp lost equilibrium. Silver carp, largemouth bass, and bluegill also showed avoidance of CO2 at approximately 100 mg.L-1. Together, results suggest that zones of elevated CO2 have potential to deter the movement of fishes.

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... Non-structural deterrents can alter fish behaviour to produce avoidance responses as documented for acoustic, visual or low-concentration CO 2 deterrents (Vetter et al., 2015;Cupp et al., 2016;Dennis et al., 2019;Putland and Mensinger, 2019;Dennis and Sorensen, 2020), or they can alter fish physiology to limit the capacity to move, as documented for electrical and higher concentration CO 2 (Suski, 2020) deterrents. Many fish species detect CO 2 concentrations through chemoreceptors in their gills (Gilmour, 2001) and use this information to avoid suboptimal, hypercapnic environments (Kates et al., 2012;Donaldson et al., 2016;Suski, 2020). Increased CO 2 concentrations are often associated with decreased O 2 concentrations, but can also affect gas exchange at the gills and induce hyperventilation (Gilmour, 2001;Perry and Gilmour, 2002). ...
... Recent deterrent efforts have been applied towards limiting the continued dispersal of invasive bigheaded carps (Hypothalmichthys spp.) within the Mississippi river basin (Kates et al., 2012;Donaldson et al., 2016). However, most CO 2 deterrent studies have been conducted in the laboratory (see Kates et al., 2012;Dennis et al., 2015;Dennis et al., 2016;Cupp et al., 2017;Tucker et al., 2018) or within artificial environments (see Donaldson et al., 2016;Cupp et al., 2016;Schneider et al., 2018). ...
... Recent deterrent efforts have been applied towards limiting the continued dispersal of invasive bigheaded carps (Hypothalmichthys spp.) within the Mississippi river basin (Kates et al., 2012;Donaldson et al., 2016). However, most CO 2 deterrent studies have been conducted in the laboratory (see Kates et al., 2012;Dennis et al., 2015;Dennis et al., 2016;Cupp et al., 2017;Tucker et al., 2018) or within artificial environments (see Donaldson et al., 2016;Cupp et al., 2016;Schneider et al., 2018). There remains a paucity of information on CO 2 deterrent performance within realistic site conditions (but see Cupp et al., 2018). ...
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Biological invasions are poorly controlled and contribute to the loss of ecosystem services and function. Altered watershed connectivity contributes to aquatic invasions, but such hydrologic connections have become important for human transport. Carbon dioxide (CO2) deterrents have been proposed to control the range expansion of invasive fishes, particularly through altered hydrologic connections, without impeding human transport. However, the effectiveness of CO2 deterrents needs to be further evaluated in the field, where fishes are situated in their natural environment and logistical challenges are present. We deployed a proof-of-concept CO2 deterrent within a trap-and-sort fishway in Cootes Paradise, Ontario, Canada, to determine the avoidance responses of fishes attempting to disperse into a wetland. We aimed to describe deterrent efficiency for our target species, common carp, and for native fishes dispersing into the wetland. Our inexpensive inline CO2 deterrent was deployed quickly and rapidly produced a CO2 plume of 60 mg/l. Over 2000 fishes, representing 13 species, were captured between 23 May and 8 July 2019. A generalized linear model determined that the catch rates of our target species, common carp (n = 1662), decreased significantly during deterrent activation, with catch rates falling from 2.56 to 0.26 individuals per hour. Aggregated catch rates for low-abundance species (n < 150 individuals per species) also decreased, while catch rates for non-target brown bullhead (n = 294) increased. Species did not express a phylogenetic signal in avoidance responses. These results indicate that CO2 deterrents produce a robust common carp avoidance response in the field. This pilot study deployed an inexpensive and rapidly operating deterrent, but to be a reliable management tool, permanent deterrents would need to produce a more concentrated CO2 plume with greater infrastructural support.
... Sullivan et al. (2016) found that Largemouth Bass Micropterus salmoides were repelled by strobe lights across a wide range of light wavelengths and pulsing frequencies. A number of studies had some measure of success in the use of stroboscopic light as a component of or as a "stand-alone," nonphysical deterrent (Nemeth and Anderson 1992;Brown 2000;Königson et al. 2002;Richards et al. 2007;Kates et al. 2012;Sullivan et al. 2016). ...
... To address fish motivation, we attempted to push individuals out of the "home chamber" of a two-chamber "shuttle box" by progressively degrading its environment with increasing CO 2 . Carbon dioxide was used to reduce environmental quality, as past studies with similar choicearena environments have used CO 2 to motivate fish to leave their occupied chamber (Kates et al. 2012;Dennis et al. 2015Dennis et al. , 2016Tucker et al. 2018). ...
... The trials were conducted in a modified shuttle-box choice arena (Loligo, Inc., Hobro, Denmark) following the procedures that are described by Kates et al. (2012). The arena was comprised of two large chambers (80.5 cm in diameter) with a connecting channel (20.2 × 12.6 cm). ...
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Biological invasions erode ecosystem functioning and occur more frequently in freshwater ecosystems than terrestrial environments. Non‐physical deterrents may be used to limit invasive fish dispersal without altering the streamflow or connectivity of a watershed. Little is currently known about how behavioural variation among individuals may effect deterrent efficacy, although such variation has been shown to affect fish dispersal in other contexts, such as range expansion. Furthermore, deterrent effectiveness is rarely tested when fish are motivated to disperse. Across a control, CO2, and CO2 + deterrent treatment, we quantified the avoidance response of invasive Common Carp (Cyprinus carpio) to a combined acoustic‐stroboscopic deterrent. In the CO2 treatment, we motivated individuals to enter a novel environment by degrading the home chamber of a choice arena with a continuous infusion of CO2. In the CO2 + deterrent treatment we introduced acoustic and stroboscopic stimuli to delay fish departure and evaluate deterrent efficacy. Finally, we tested a subset of the fish multiple times to determine if fish consistently responded to the same concentration of CO2. We found that the acoustic and stroboscopic stimuli could detain fish in an increasingly unfavorable environment. Common Carp only took 195 and 131 seconds to swim between chambers during the control and CO2 treatment, but took an average of 596 seconds in the CO2 + deterrent treatment. High CO2 concentrations in the CO2 + deterrent treatment led to most fish eventually dispersing towards the deterrent stimuli. Avoidance behaviour varied widely within the CO2 + deterrent treatment, and Common Carp expressed repeatable differences in the tank‐inflow CO2 concentrations observed during chamber departure. Such inter‐individual variation in deterrent avoidance indicates that some individuals within a given species are more likely to move past a deterrent than others.
... Furthermore, the water may be mixed horizontally by animal movement, which may render subsequent occurrence analyses imprecise. Issues with unwanted water mixing and stratification can be reduced significantly by having physically separated choice chambers that are interconnected by narrow passages for the animal, such as so-called shuttle-boxes, which provides stable water separation for a variety of environmental variables (Schurmann et al., 1991;Serrano et al., 2010;Kates et al., 2012;Borowiec et al., 2018). ...
... In later years, the term 'shuttle-box' has become synonymous with a system that also consists of two physically separated choice chambers interconnected via a small passage but where one or both of the choice chambers are maintained at a static level (e.g. Kates et al. 2012;Tix et al. 2018). We have therefore included studies with both usages of the term in the present review and differentiate between them as 'dynamic shuttle-boxes' and 'static shuttle-boxes'. ...
... Over time, the shuttle-box has been redeveloped significantly both with respect to basic set up and experimental application (e.g. Reynolds, 1977;Schurmann and Christiansen, 1994;Serrano et al., 2010;Herbert et al., 2012;Kates et al., 2012;Cooper et al., 2018). The many different directions of use of the system may affect repeatability and comparability of studies, and we have therefore systematically reviewed the use of shuttle-boxes for determining environmental preference and avoidance by aquatic animals. ...
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Article
Animals' selection of environments within a preferred range is key to understanding their habitat selection, tolerance to stressors and responses to environmental change. For aquatic animals, preferred environmental ranges can be studied in so-called shuttle-boxes, where an animal can choose its ambient environment by shuttling between separate choice chambers with differences in an environmental variable. Over time, researchers have refined the shuttle-box technology and applied them in many different research contexts, and we here review the use of shuttle-boxes as a research tool with aquatic animals over the past 50 years. Most studies on the methodology have been published in the latest decade, probably due to an increasing research interest in the effects of environmental change, which underlines the current popularity of the system. The shuttle-box has been applied to a wide range of research topics with regards to preferred ranges of temperature, CO 2 , salinity and O 2 in a vast diversity of species, showing broad applicability for the system. We have synthesized the current state-of-the-art of the methodology and provided best practice guidelines with regards to setup, data analyses, experimental design and study reporting. We have also identified a series of knowledge gaps, which can and should be addressed in future studies. We conclude with highlighting directions for research using shuttle-boxes within evolutionary biology and behavioural and physiological ecology.
... Over time, this pH imbalance is corrected as fish uptake HCO 3 − from the environment (in exchange for Cl − ) and excrete H + (in exchange for Na + ) [63]. Owing to this influx of CO 2 , hypercarbic environments cause an elevation of the general stress response [64][65][66], a drop in blood pH [67], a loss of ions [68], and, ultimately, equilibrium loss and anesthesia (Stage 2 or Stage 3) [64,67,69,70]. At present, the exact mechanism(s) responsible for the loss of equilibrium and the anesthetic impacts of carbon dioxide have not been well defined, but are believed to result from the movement of CO 2 across the blood-brain barrier, which alters brain pH and an impairs brain electrical activity [71,72]; additions of H + or HCO 3 − alone will not result in anesthesia for fish [71]. ...
... For example, Ross et al. [80] exposed book trout, slimy sculpin (Cottus cognatus) and blacknose dace to four levels of CO 2 (0%, 1.4%, 2.8% and 5.1%) for either one or 24 h and noted differences in physiological responses both across species and across exposure durations, suggesting species-specific responses to CO 2 exposure. To address this need and define concentrations that induced onset of disturbances, Kates et al. [66] exposed bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), silver carp (>450 mm) and bighead carp (>700 mm) to two different concentrations of CO 2 (30 mg/L and 70 mg/L) for three hours and showed that, 30 mg/L CO 2 (approximately 2000 µatm CO 2 ) had minimal physiological or behavioral impacts, but a three hour exposure to 70 mg/L CO 2 (approximately 50,000 µatm CO 2 ) resulted in a drop in ventilation rates, and an increase in irregular behaviors such as erratic swimming, twitching and escape attempts for silver carp and bighead carp [66]. One of the challenges with the study by Kates et al. [66], however, was that adult bigheaded carp were used, which provided little evidence in support of how small fish, those presumably less vulnerable to the existing electric barriers in Romeoville, IL, would respond to CO 2 . ...
... For example, Ross et al. [80] exposed book trout, slimy sculpin (Cottus cognatus) and blacknose dace to four levels of CO 2 (0%, 1.4%, 2.8% and 5.1%) for either one or 24 h and noted differences in physiological responses both across species and across exposure durations, suggesting species-specific responses to CO 2 exposure. To address this need and define concentrations that induced onset of disturbances, Kates et al. [66] exposed bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), silver carp (>450 mm) and bighead carp (>700 mm) to two different concentrations of CO 2 (30 mg/L and 70 mg/L) for three hours and showed that, 30 mg/L CO 2 (approximately 2000 µatm CO 2 ) had minimal physiological or behavioral impacts, but a three hour exposure to 70 mg/L CO 2 (approximately 50,000 µatm CO 2 ) resulted in a drop in ventilation rates, and an increase in irregular behaviors such as erratic swimming, twitching and escape attempts for silver carp and bighead carp [66]. One of the challenges with the study by Kates et al. [66], however, was that adult bigheaded carp were used, which provided little evidence in support of how small fish, those presumably less vulnerable to the existing electric barriers in Romeoville, IL, would respond to CO 2 . ...
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Article
Invasive species are a threat to biodiversity in freshwater. Removing an aquatic invasive species following arrival is almost impossible, and preventing introduction is a more viable management option. Bigheaded carp are an invasive fish spreading throughout the Midwestern United States and are threatening to enter the Great Lakes. This review outlines the development of carbon dioxide gas (CO2) as a non-physical barrier that can be used to deter the movement of fish and prevent further spread. Carbon dioxide gas could be used as a deterrent either to cause avoidance (i.e., fish swim away from zones of high CO2), or by inducing equilibrium loss due to the anesthetic properties of CO2 (i.e., tolerance). The development of CO2 as a fish deterrent started with controlled laboratory experiments demonstrating stress and avoidance, and then progressed to larger field applications demonstrating avoidance at scales that approach real-world scenarios. In addition, factors that influence the effectiveness of CO2 as a fish barrier are discussed, outlining conditions that could make CO2 less effective in the field; these factors that influence efficacy would be of interest to managers using CO2 to target other fish species, or those using other non-physical barriers for fish.
... Carbon dioxide (CO 2 ) has shown promise in controlling invasive and nuisance fishes (Wu and Bridges 2014;Cupp et al. 2017b, c) and could be an effective tool in an integrated pest management program to control invasive crayfish. Laboratory and pond studies using telemetered fish conclusively demonstrate that fish avoid waters with elevated CO 2 (Kates et al. 2012;Dennis et al. 2016;Cupp et al. 2017a). Additionally, CO 2 , in the form of dry ice, has been used in controlled pond studies with invasive silver carp (Hypophthalmichthys molitrix Valenciennes, 1844) and bighead carp (Hypophthalmichthys nobilis Richardson, 1845) to determine the efficacy of under-ice treatments as a control method ). ...
... A digital video camera (acA1300-30gc, Basler, Ahrensburg, Germany) was installed above the shuttle box to record crayfish activity. The shuttle box was behind a black liner suspended from wall to wall to separate the test system from the observer and minimize behavioral changes resulting from activity in the room (Kates et al. 2012). ...
... Ten LOE trials were performed for each species at both temperatures (10 and 24 °C). CO 2 concentrations required to achieve loss of equilibrium were determined following methods previously described (Kates et al. 2012;Cupp et al. 2017b;Tix et al. 2018). Briefly, a dark colored bucket was filled with 10 L of temperature-conditioned well water. ...
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Article
Few effective strategies are available to control invasive crayfishes. Carbon dioxide (CO2) acts as a behavioral deterrent for invasive fishes and could be a useful crayfish control tool. The objective of this laboratory study was to quantify CO2 concentrations that caused red swamp crayfish (RSC; Procambarus clarkii) and rusty crayfish (RYC; Faxonius rusticus) avoidance behavior, altered emergence behavior, and caused loss of equilibrium. Behavioral endpoints were quantified under light and dark conditions and at 10 and 24 °C. Avoidance responses from both species varied widely. Under light conditions, 35 mg/L CO2 was needed to induce the first avoidance shuttle in both crayfish species at 10 °C. CO2 concentrations of 42 mg/L for RYC and 46 mg/L for RSC were required for first shuttle at 24 °C. The first avoidance shuttle was induced at 37 mg/L CO2 for RYC and 54 mg/L CO2 for RSC at 10 °C in the dark. At 24 °C, 44 mg/L CO2 was required for first shuttle for both species. Less CO2 was needed to cause the last avoidance shuttle in RYC compared to RSC at both temperatures and under both lighting conditions. RSC emergence occurred at 418 ± 77 mg/L CO2, and loss of equilibrium occurred for both species at 1,231 ± 201 mg/L CO2. RYC appeared to be more sensitive than RSC to CO2, but behavior did not differ among light and water temperature treatments. These results demonstrate that CO2 alters crayfish behavior. The CO2 concentrations identified during this study may inform field testing to develop CO2 as a potential control tool for invasive crayfishes.
... The impacts of high dissolved CO 2 and weak acidification on aquatic biota are largely unknown (Hasler et al. , 2018; however, some studies on freshwater fishes and invertebrates have been completed. Broadly, high CO 2 is known to have several behavioral and physiological effects on freshwater fishes (e.g., Heuer and Grosell 2014;Tierney 2016), but the exact outcomes vary and likely are dependent on CO 2 level and length of exposure (Kates et al. 2012). Lab studies have shown several trends, including loss of predator awareness (Tix et al. 2017), altered behavior , and loss of equilibrium (Kates et al. 2012) when exposed to elevated CO 2 . ...
... Broadly, high CO 2 is known to have several behavioral and physiological effects on freshwater fishes (e.g., Heuer and Grosell 2014;Tierney 2016), but the exact outcomes vary and likely are dependent on CO 2 level and length of exposure (Kates et al. 2012). Lab studies have shown several trends, including loss of predator awareness (Tix et al. 2017), altered behavior , and loss of equilibrium (Kates et al. 2012) when exposed to elevated CO 2 . Due to the suite of physiological and behavioral effects that hypercarbia has on fishes, the use of plumes of intentionally elevated CO 2 to prevent the movement of invasive fishes (e.g., bigheaded carp) has been explored Treanor et al. 2017). ...
... Though there is variation in how fish respond to prolonged exposure to high CO 2 , avoidance of high CO 2 seems to be robust across freshwater fishes Dennis et al. 2016a; Kates et al. 2012) and across magnitude of exposure (Donaldson et al. 2016), likely as fish seek out improved water quality to avoid potential costs from CO 2 exposure. For this reason, injection of CO 2 into canal locks is being considered as a method to limit the distribution of invasive species in the Mississippi River and elsewhere (Treanor et al. 2017), particularly bigheaded carp (Hypophthalmichthys spp.; Noatch and Suski 2012). ...
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Article
Deterring the spread of invasive fishes is a challenge for managers, and bigheaded carp (including bighead and silver carp, Hypophthalmichthys spp.) are invasive fish that have spread throughout large portions of the Mississippi River basin and threaten to invade the Great Lakes’ ecosystem. Studies have shown that elevated levels of carbon dioxide gas (CO2) have the ability to act as a nonphysical fish barrier, but little work has been done on the efficacy of CO2 to deter fish movement in flowing water. An annular swim flume was used to measure Uburst and sprint duration of the model species largemouth bass (Micropterus salmoides) across a range of pCO2 levels (< 400 μatm [ambient]; 10,000 μatm; 50,000 μatm; and 100,000 μatm). This species was tested as a proxy because of the likelihood of a similar CO2 response being produced, as well as constraints in obtaining and housing appropriately sized Asian carp. A significant decrease in Uburst swimming occurred when exposed to 100,000 μatm. No effects on sprint duration were detected. In both swimming tests, 15% of fish lost equilibrium when exposed to 50,000 μatm pCO2, while 50% of fish lost equilibrium when exposed to 100,000 μatm. Together, results define target levels for managers to impede the spread of largemouth bass and potentially other invasive freshwater fishes, helping guide policy to conserve aquatic ecosystems.
... Infusion of carbon dioxide (CO 2 ) into water has shown promise as a chemical fish deterrent that could be useful to as a non-physical means to block the movements and passage of bigheaded carps and other invasive fishes. Results from laboratory experiments showed that fish consistently avoided CO 2 -enriched water when given access to ambient freshwater areas (Kates et al. 2012;Dennis et al. 2016;Cupp et al. 2017c). Subsequent studies at larger spatial scales in outdoor ponds documented similar avoidance behaviors with telemetered bigheaded carps exposed to CO 2 enriched water under flowing and static conditions (Donaldson et al. 2016;Cupp et al. 2017a). ...
... Based on a review of published literature, we expected to see a decrease in fish abundance and occupancy around the WMS culvert entrances during treatments at approximately 100 mg/L CO 2 . More specifically, upstream movements of invasive bigheaded carps were reduced by approximately 50% in outdoor ponds at 70-100 mg/L CO 2 and this threshold would be a reasonable target for field testing (Kates et al. 2012;Donaldson et al. 2016;Cupp et al. 2017a). Results from this study provide several considerations for CO 2 as a fish deterrent in natural environments. ...
... Gas flow rates were set to approximately 7-10 L/min per diffuser until tanks emptied and all trials were conducted using similar injection parameters. A target CO 2 concentration for each flow regime was set at 100 mg/L as previous research has shown freshwater fish including invasive Bigheaded Carps strongly avoid CO 2 at this level in laboratory and pond experiments (Kates et al. 2012;Donaldson et al. 2016, Dennis et al. 2016). ...
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Article
Construction of a water management structure (WMS) in the levee surrounding The Nature Conservancy’s Emiquon Preserve (Havana, Illinois, USA) created a new hydrological connection and potential aquatic invasive species pathway between the Illinois River and a large conservation wetland complex. Site managers need a control tool that deters the upstream passage of non-native fishes into the wetland lakes, but does not interfere with normal gate operation and water discharge. This short field study evaluated carbon dioxide (CO2) injected into water as a non-obstructive method to reduce fish abundance near the WMS culverts. We quantified relative fish abundance using underwater sonar with and without injection of CO2 into culverts during three discharge events: no flow (0 m³/s), restricted flow (0.9 m³/s), and unrestricted flow (3.2 m³/s). Overall, CO2 reached or exceeded our target concentration of 100 mg/L during no flow and restricted flow, and fish abundance was 70–95% lower at culvert entrances relative to untreated control days. The target CO2 level was not reached during unrestricted flow and fish abundance was not reduced during CO2 injection. Atmospheric CO2 concentrations were inconsequential and unaffected by CO2 treatments throughout testing. Results from this initial field study provide several considerations for CO2 as a fish deterrent in natural environments.
... Partial pressures of CO 2 (pCO 2 ) in fresh water can vary greatly both spatially and temporally (Crawford et al. 2017), and are influenced by factors such as stream order, terrestrial productivity, aquatic respiration, overland flow, land-use, and underlying geology (Butman and Raymond 2011;Hasler et al. 2016a). Fish may also experience elevated pCO 2 upon encountering non-physical fish barriers (Kates et al. 2012;Noakes and Jones 2016;Treanor et al. 2017). Studies have shown that once a certain threshold of pCO 2 has been reached (approximately 50,000-75,000 latm (5.07-7.60 kPa)), fish will choose to voluntarily swim away from areas of elevated pCO 2 , presumably to minimize costs related to inhabiting degraded water quality (e.g., upregulation of the stress axis, increased metabolic rate, etc.). ...
... Studies have shown that once a certain threshold of pCO 2 has been reached (approximately 50,000-75,000 latm (5.07-7.60 kPa)), fish will choose to voluntarily swim away from areas of elevated pCO 2 , presumably to minimize costs related to inhabiting degraded water quality (e.g., upregulation of the stress axis, increased metabolic rate, etc.). Avoidance responses by fish to high pCO 2 have been demonstrated for several species, size classes, and environments (Kates et al. 2012;Dennis et al. 2015aDennis et al. , 2016. Despite the clear presence of this threshold to induce avoidance, there is considerable variation around this mean, likely driven in part by inter-individual variation in avoidance of CO 2 (Kates et al. 2012;Dennis III et al. 2015a, b, 2016Hasler et al. 2017). ...
... Avoidance responses by fish to high pCO 2 have been demonstrated for several species, size classes, and environments (Kates et al. 2012;Dennis et al. 2015aDennis et al. , 2016. Despite the clear presence of this threshold to induce avoidance, there is considerable variation around this mean, likely driven in part by inter-individual variation in avoidance of CO 2 (Kates et al. 2012;Dennis III et al. 2015a, b, 2016Hasler et al. 2017). To date, the roles that stress hormones or personality may play in influencing the avoidance of fish to areas of high pCO 2 have not been defined. ...
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Organismal responses to stressors can be influenced by several internal and external factors including physiological condition and inherent behavioral type. Carbon dioxide (CO2), a known stressor for fish, is naturally increasing in fresh water, and has been proposed as a non-physical barrier to prevent invasive fish movement. Intraspecific differences in how fish respond to CO2 challenges have been noted, with some individuals responding at low partial pressures of CO2 (pCO2), and others responding at higher pCO2. Sensitivity to pCO2 may play a role in avoidance behaviors with respect to CO2 barriers and may predict how fish respond to naturally occurring CO2 challenges. We sought to determine the role that both physiological condition (i.e., elevated cortisol) and personality (i.e., boldness) play in influencing behavioral responses. To accomplish this goal, a shuttle box assay was used to determine the pCO2 that elicited avoidance in cortisol-injected or non-injected largemouth bass (Micropterus salmoides), as well as bold or shy bluegill (Lepomis macrochirus). Cortisol-injected largemouth bass shuttled at 45% higher pCO2 than control fish, but personality of bluegill had no effect on shuttling. It appears that an individual’s cortisol level can affect CO2 avoidance, likely mediated through the effects of cortisol on acid–base balance at the gill, or through the effects of cortisol on coping styles. Our finding has important implications for how fish respond to either natural or anthropogenically-driven changes in CO2, as stressed fish with high cortisol would appear to be more tolerant of elevated CO2, independent of personality type.
... Dissolved carbon dioxide (CO 2 ) has previously been shown to alter the movement of Hypophthalmichthys sp. (regardless of size) during laboratory (Kates et al. 2012;Dennis et al. 2015) and pond testing Donaldson et al. 2016) and could be a viable non-physical strategy to block unwanted fish movements. Acute exposure to increased CO 2 concentrations can result in behaviors such as erratic swimming (Kates et al. 2012), increased activity , gill ventilations (Heisler 1989), fin beats and surface attempts (Ross et al. 2001). ...
... (regardless of size) during laboratory (Kates et al. 2012;Dennis et al. 2015) and pond testing Donaldson et al. 2016) and could be a viable non-physical strategy to block unwanted fish movements. Acute exposure to increased CO 2 concentrations can result in behaviors such as erratic swimming (Kates et al. 2012), increased activity , gill ventilations (Heisler 1989), fin beats and surface attempts (Ross et al. 2001). While prolonged exposure to elevated CO 2 concentrations may result in respiratory acidosis which will cause a disruption in cellular ionic gradients (Nilsson et al. 2012;Heuer and Grosell 2014) causing alterations to fish physiology [increased plasma glucose and altered cortisol levels (Ross et al. 2001)] and behaviors [predator avoidance and alarm cue responses ]. ...
... Carbon-dioxide avoidance was evaluated at different temperatures for silver carp and bighead carp using a shuttle-box choice tank (Loligo Systems Inc., Viborg, Denmark; see figure in Kates et al. 2012) following methods described in Cupp et al. (2017c). Unlike in Cupp et al. (2017c), we did not add rock substrate to one side of the choice tank due to bigheaded carps being more pelagic swimmers than round goby. ...
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Effective behavioral deterrents are needed to prevent aquatic invasive species from entering novel ecosystems. One deterrent strategy that shows promise is elevated carbon dioxide (CO2) concentrations in water which can alter the behavior of freshwater fishes, including invasive bigheaded carps (Hypophthalmichthys spp.). However, few studies have evaluated behavioral responses to elevated CO2 concentrations at different water temperatures. The objective of this study was to quantify CO2 concentrations needed to achieve avoidance (voluntary response) and narcosis (involuntary response observed by loss of equilibrium) behaviors in silver carp (H. molitrix) and bighead carp (H. nobilis) at 5, 15, and 25 °C. Overall, silver carp and bighead carp displayed avoidance and narcosis behaviors to CO2 at each water temperature, however bighead carp responded at higher CO2 concentrations than silver carp. Behavioral avoidance and narcosis were observed at approximately 40% lower CO2 concentrations in 5 °C water relative to 25 °C suggesting considerable influence of water temperature on a CO2 stimulus for both species. Results indicate that fluctuating water temperature (e.g., spatial and temporal variation across management sites) can influence how fish respond to elevated CO2, and may usefully be considered when applying CO2 as a behavioral deterrent.
... Carbon dioxide (CO 2 ) is a naturally occurring compound shown to induce avoidance behaviors in fish (Kates et al. 2012;Dennis et al. 2016b;Donaldson et al. 2016). Elevated in aquatic systems through both natural and anthropogenic sources, CO 2 is readily detected by fishes even at low concentrations (Cummins et al. 2014). ...
... For example, despite the ability of fish to regulate intra-and extra-cellular pH to some degree, elevated pCO 2 may reduce their ability to uptake and transport oxygen, thus having implications for aerobic metabolism (Heuer and Grosell 2014). In laboratory studies in static tanks, fish display behavioral and physiological modifications such as erratic ventilations and increased plasma glucose as part of the stress response at low CO 2 levels, whereas at higher concentrations fish will display avoidance (Kates et al. 2012), highlighting the negative impact that environmental CO 2 can have on fish. Due to elevated CO 2 levels inducing avoidance in fish, CO 2 has been recommended for investigation as a potential non-physical fish deterrent United States Army Corps of Engineers 2014). ...
... While the avoidance of fishes to elevated CO 2 is well documented (Kates et al. 2012;Noatch and Suski 2012; United States Army Corps of Engineers 2014; Donaldson et al. 2016), three unresolved issues are impairing the ability to successfully design and implement a CO 2 barrier in a field setting. First, to date, studies have not been performed to specifically define avoidance thresholds of pCO 2 (CO 2 pressure at which there is no response seen below, but a consistent, predictable response above). ...
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Preventing the spread of invasive fishes is an important aspect of management programs, but is challenging due to the behavior of fish and the nature of aquatic environments. The use of dissolved carbon dioxide (CO2) has recently gained traction as a non-physical barrier for invasive fishes due to its ability to elicit avoidance behaviors in fish. Research to date has focused on the development of CO2 barriers using static water environments. Because CO2 barriers have been proposed for flowing water (i.e., in rivers or shipping canals), understanding the dynamics between fish and elevated CO2 in flowing water is essential. Our study aims to define threshold levels required to alter behavior of bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) in flowing water, and to quantify behavioral metrics of fish exposed to < 200 [ambient], 25,000, 50,000, and 100,000 µatm pCO2. We also sought to quantify the impacts of repeated CO2 exposure on fish behavior. Bluegill showed increased activity at 25,000 µatm, while largemouth bass showed increased activity at 100,000 µatm. When repeatedly exposed to cycles of 50,000 µatm pCO2, bluegill exhibited increased activity followed by a diminished response after the second exposure. Results from this study define threshold levels required to elicit behavioral responses, and show that the effects that multiple exposures of elevated pCO2 can decline, possibly due to habituation. Results will help shape the development and deployment of a CO2 barrier to control the movements of invasive fishes.
... In freshwater environments, fish consistently avoid CO 2 sources (Clingerman et al. 2007;Dennis et al. 2016;Donaldson et al. 2016). For fish that cannot escape CO 2 -rich water, behavioral changes include increased gill ventilation (Heisler 1989;Ross et al. 2001), increased fin beats, listing, increased attempts to surface (Ross et al. 2001), erratic swimming (Kates et al. 2012;Dennis et al. 2016), impaired sensory systems (Munday et al. 2009), and loss of lateralization (Domenici et al. 2012). Sustained exposure leads to a loss of reflex and opercular activity (Post 1979) and loss of equilibrium (Ross et al. 2001;Kates et al. 2012;Dennis et al. 2016). ...
... For fish that cannot escape CO 2 -rich water, behavioral changes include increased gill ventilation (Heisler 1989;Ross et al. 2001), increased fin beats, listing, increased attempts to surface (Ross et al. 2001), erratic swimming (Kates et al. 2012;Dennis et al. 2016), impaired sensory systems (Munday et al. 2009), and loss of lateralization (Domenici et al. 2012). Sustained exposure leads to a loss of reflex and opercular activity (Post 1979) and loss of equilibrium (Ross et al. 2001;Kates et al. 2012;Dennis et al. 2016). Finally, Ross et al. (2001) also documented that fish exposed to elevated CO 2 spend less time feeding and engaging in social interactions with other fish. ...
... Research examining the potential use of CO 2 for aquatic invasive invertebrates control is increasing (Kates et al. 2012;Nielson et al. 2012;Abbey-Lambertz et al. 2014;Donaldson et al. 2016). ...
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Article
To restore native fish populations, fisheries programs often depend on active removal of aquatic invasive species. Chemical removal can be an effective method of eliminating aquatic invasive species, but chemicals can induce mortality in nontarget organisms and persist in the environment. Carbon dioxide (CO2) is an emerging alternative to traditional chemical control agents because it has been demonstrated to be toxic to fish, but is naturally occurring and readily neutralized. In addition, CO2 is a commercially available gas, is highly soluble, and has high absorption efficiency. When these characteristics are paired with advances in modern, large-scale gas delivery technologies, opportunities to use CO2 in natural or artificial (e.g., canals) waters to manage fish become increasingly feasible. Our objective is to describe the history of CO2 use in fisheries and outline potential future applications of CO2 to suppress and manipulate aquatic species in field and aquaculture settings.
... Fish detect CO 2 through branchial chemoreceptors (Ishimatsu et al. 2005;Perry and Abdallah 2012) and respond by avoiding those areas or becoming incapacitated through narcosis . A few laboratory studies have found that CO 2 was effective to alter the behavior of invasive sea lamprey (Petromyzon marinus Linnaeus, 1758), silver carp (Hypophthalmichthys molitrix Valenciennes, 1844), bighead carp (Hypophthalmichthys nobilis Richardson, 1845) and several native fishes (Kates et al. 2012;Dennis et al. 2015Dennis et al. , 2016. Tracking of telemetered fish in outdoor ponds also showed that CO 2 could be used to exclude bigheaded carps (Hypophthalmichthys spp. ...
... Round goby avoidance was determined using a shuttle box choice arena (Loligo Systems Inc., Viborg, Denmark) from modified methods described in Kates et al. (2012). Briefly, the experimental setup consisted of two circular tanks (dimensions: 1.5 m wide × 0.5 m deep) connected by a narrow, rectangular passageway (dimensions: 0.2 m wide × 0.5 m deep). ...
... Carbon dioxide has received considerable recent attention as a non-physical deterrent to invasive bigheaded carp movement (Kates et al. 2012;Donaldson et al. 2016;Cupp et al. 2017a), and this study found similar behavioral responses with round goby. Across all temperatures, round goby swam away from CO 2 once a threshold of 99-169 mg/L (79,000-178,000 µatm) was reached and lost equilibrium at 197-280 mg/L CO 2 (163,000-303,000 µatm). ...
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Article
Fisheries managers need effective methods to limit the spread of invasive round goby Neogobius melanostomus in North America. Elevating carbon dioxide (CO2) in water at pinch points of rivers (e.g., inside locks) is one approach showing potential to deter the passage of invasive fishes, such as bigheaded carps Hypophthalmichthys spp., but the effectiveness of this method to alter round goby behavior has not been determined. The goal for this study was to determine CO2 concentrations that alter round goby behavior across a range of water temperatures. Free-swimming avoidance (voluntary response) and loss of equilibrium (involuntary response) were quantified by exposing round goby to increasing CO2 concentrations at 5, 15, and 25 °C using a shuttle box choice arena and static tank. Water chemistry was measured concurrent with behavioral endpoints and showed that round goby avoided a threshold of 99–169 mg/L CO2 (79,000–178,000 µatm) and lost equilibrium at 197–280 mg/L CO2 (163,000–303,000 µatm). Approximately 50% lower CO2 concentrations were found to modify behavior at 5 °C relative to 25 °C, suggesting greater effectiveness at lower water temperatures. We conclude that CO2 modified round goby behavior and concentrations determined in this study are intended to guide field testing of CO2 as an invasive fish deterrent.
... The infusion of carbon dioxide gas (CO 2 ) into water has recently been explored as a deterrent to bigheaded carps (Kates et al. 2012). The ability of animals to sense environmental CO 2 is highly conserved across taxa (Cummins et al. 2014) and fish have externally oriented, branchial CO 2 -sensitive chemoreceptors that enable the detection of CO 2 (Gilmour 2001). ...
... Fish will avoid locations that contain CO 2 that falls outside their preferred concentration range (Fromm 1980;Gilmour 2001). In a laboratory study, Kates et al. (2012) found that the addition of 100 mg/L of CO 2 to water resulted in the exclusion of adult Bighead and Silver carps and native fish species from the infusion area, and even lower concentrations resulted in reflex, behavioral (e.g., avoidance responses), and physiological responses. Carbon dioxide exposure has been shown to trigger a physiological response and to limit the movement of several species, including bigheaded carps (Dennis et al. 2015a(Dennis et al. , 2015b. ...
... A CO 2 digital titration kit (Hach, titrator model 16900, kit number 227270) was also used to test water samples drawn from the peristaltic pump. The use of pH as a proxy for CO 2 is common, because pH measurements are rapid and relatively inexpensive to measure with field meters, and there is a strong, near-linear relationship between pH and CO 2 concentrations (Wurts and Durborow 1992;Kates et al. 2012;Esbaugh et al. 2012). Water pH inside the manifold was monitored using a single sonde at the midline and two pH probes placed on either side. ...
Article
Nonnative bigheaded carps are established in the Mississippi River and there is substantial concern about their potential entry into the interconnected Laurentian Great Lakes. While electrical barriers currently exist as a preventative measure, there is need for additional control mechanisms to promote barrier security through redundancy. We tested the effectiveness of infused carbon dioxide gas (CO2) as a tool to influence the movement and behavior invasive bigheaded carps, namely Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix, as well as native Bigmouth Buffalo Ictiobus cyprinellus, Channel Catfish Ictalurus punctatus, Paddlefish Polyodon spathula, and Yellow Perch Perca flavescens in an experimental pond. Individuals were monitored with acoustic telemetry before, during, and after CO2 addition to the pond. We noted distinct changes in fish behavior following CO2 addition. Each species except Paddlefish maintained farther distances from the CO2 infusion manifold relative to controls. Both bigheaded carp species had slower persistence velocities (persistence of a movement in a given direction) following CO2 infusion and Bighead Carp used a smaller area of the pond immediately after CO2 addition. Pond pH progressively decreased up to 1.5 units following CO2 infusion. This work provides evidence that could inform future research to enhance existing control measures used to deter high-risk invasive fishes, such as bigheaded carps. Received July 27, 2015; accepted January 11, 2016 Published online April 27, 2016
... Several studies have started to characterize fish behavior during CO 2 exposure. Choice-chamber experiments in indoor laboratories found that invasive fishes moved away from CO 2 treated tanks in favor of untreated tanks (Dennis et al., 2016(Dennis et al., , 2015Kates et al., 2012;Tix et al., 2017;Tucker et al., 2019). Avoidance responses were relatively similar across species, life stages, and water temperatures (Cupp et al., 2017a(Cupp et al., , 2017cDennis et al., 2015Dennis et al., , 2016Tix et al., 2018), and fish generally did not acclimate with prolonged or repeated exposures to a CO 2 stimulus Tix et al., 2017). ...
... The overall setup created a pond that was geometrically and hydrologically identical on both sides. Similar to the small choice-chamber tanks used during laboratory testing with CO 2 , this pond setup allowed us to treat one area with CO 2 while the other received no CO 2 and served as a refuge (Kates et al., 2012). ...
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Article
Carbon dioxide (CO 2) mixed into water is being explored as a possible management strategy to deter the upstream movements of invasive carps through navigation locks and other migratory pinch-points. This study used two-dimensional acoustic telemetry to assess the effectiveness of dissolved CO 2 as a chemosensory deterrent to two carp species in a large U-shaped pond. Free-swimming movements of telemetered bighead carp (Hypophthalmichthys nobilis) and grass carp (Ctenopharyngodon idella) were documented 24 h before treatment and 24 h during treatments at 60, 121 and 213 mg/L CO 2 (mean concentrations in pond water). Several behavioral endpoints were then quantified and compared to evaluate deterrence efficacy. In general, results showed that both carp species responded similarly to CO 2 treatments. Carps consistently relocated into areas away from the injection site and made fewer attempts to re-enter CO 2 treated areas. On average, CO 2 treatments reduced mid-line crosses between untreated and treated sides of the pond by 58% at 121 mg/L CO 2 and 78% at 213 mg/L CO 2 relative to normal swimming movements recorded before treatment. Fish swim speeds increased significantly when inside the CO 2 plume during treatments during 213 mg/L CO 2 trials relative to swim speeds outside the plume, possibly indicative of active searching and avoidance responses. Overall, this study found that CO 2 altered the behavior of bighead carp and grass carp. Natural resource agencies could consider the CO 2 concentrations identified in this study to inform future applications to deter invasive carps from locations where they are at-risk to move upstream. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research.
... Exposure to elevated levels of CO 2 can have both sublethal and lethal effects on fishes (Gelwicks et al. 1998;Ross et al. 2001;Clingerman et al. 2007;Kates et al. 2012;Dennis et al. 2016;Tix et al. 2017;Tucker et al. 2019). Initially, contact with sublethal levels of CO 2 causes a decrease in body fluid pH, but the accumulation of bicarbonate ions in body fluids buffers this change. ...
... While several studies have addressed the physiological effects of CO 2 on fishes and invertebrates (e.g., Ishimatsu et al. 2004;Kates et al. 2012;Hannan et al. 2016;Jeffrey et al. 2017), the list of species with defined lethalities is relatively limited but growing (Treanor et al. 2017). Even though CO 2 is presently registered as a pesticide, future users of CO 2 as a fisheries management tool will benefit from knowledge of sensitivity thresholds for individual fish species . ...
Article
There is growing interest in the use of carbon dioxide (CO 2 ) as a management tool for controlling invasive fishes. However, there is limited published data on susceptibility of many commonly encountered species to elevated CO 2 concentrations. Our objective was to estimate the 24-h LC 50 and LC 95 of four fishes (Rainbow Trout Oncorhynchus mykiss , Common Carp Cyprinus carpio , Channel Catfish Ictalurus punctatus , and Westslope Cutthroat Trout Oncorhynchus clarkii lewisi ). In the laboratory, we exposed juvenile fish to a range of CO 2 concentrations for 24-h in unpressurized, flow-through tanks. A Bayesian hierarchical model was developed to estimate the dose response relationship for each fish species with associated uncertainty, and 24-h LC 50 and LC 95 values were estimated based on laboratory trials for each species. The minimum concentration inducing mortality differed among cold water-adapted species and warm water-adapted species groups: 150 mg CO 2 /L for Westslope Cutthroat Trout and Rainbow Trout and 225 mg CO 2 /L for Common Carp and Channel Catfish. We observed complete mortality at 275 mg CO 2 /L (38,672 µatm), 225 mg CO 2 /L (30,711 µatm), and 495 mg CO 2 /L (65,708 µatm (CC); 77,213 µatm (CF)) for Westslope Cutthroat Trout, Rainbow Trout, and both Common Carp and Channel Catfish, respectively. There was evidence of a statistical difference between the LC 95 values of Westslope Cutthroat Trout and Rainbow Trout (245.0 ( 222.2 to 272.2 ) and 190.6 ( 177.2 to 207.8 ) mg CO 2 /L, respectively). Additionally, these values were almost half the estimated 24-h LC 95 s for Common Carp and Channel Catfish (422.5 ( 374.7 to 474.5 ) and 434.2 ( 377.2 to 492.2 ) mg CO 2 /L, respectively). Although the experimental findings show strong relationships between increased CO 2 concentration and higher mortality, additional work is needed to assess the efficacy and feasibility of a CO 2 application in a field setting.
... For over a century, researchers have demonstrated that fish avoid areas of elevated CO 2 (Shelford and Allee 1913). Numerous recent reports describe the ability of gill-breathing animals to detect and avoid areas of elevated CO 2 (Jones et al. 1985;Perry and Gilmour 2006;Kates et al. 2012;Perry and Abdallah 2012;Jutfelt and Hedgärde 2013;Welch et al. 2014). External chemoreceptors on the gills allow fish to detect elevated ambient CO 2 (Perry and McKendry 2001;Perry and Reid 2002), and it is likely that these receptors are involved with the CO 2 detection and avoidance behaviors. ...
... Recent studies exploring CO 2 as a deterrent and barrier to invasive fish demonstrated that CO 2 at a concentration of 100-200 mg/L effectively deterred adult and juvenile Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis in laboratory trials (Kates et al. 2012;Dennis et al. 2015). More promising were the findings that behavioral responses did not change from acclimation to CO 2 (Dennis et al. 2016a), responses were observed across a range of water temperatures (Cupp et al. 2017b;Tix et al. 2018), and responses were similar across other invasive fishes, like the Round Goby Neogobius melanostomus and Sea Lamprey (Dennis et al. 2016b;Cupp et al. 2017b). ...
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Article
Chemical controls ranging from natural products to synthesized chemicals are widely used in aquatic pest management activities. Chemicals can be used to lure organisms to traps or can cause direct mortality by altering the physiological function of an organism. Much of what is known about controlling pests with chemicals is from research done on terrestrial pesticides. This paper focuses on how chemicals might be used as aquatic pesticides to control or eradicate aquatic invasive species. Current control tools are described, as are new technologies designed to selectively target the pest to reduce risks to nontarget organisms and the environment.
... Carbon dioxide was first tested as a molluscicide in 1995 and found to effectively reduce attachment of zebra mussels (McMahon et al. 1995;Payne et al. 1998) and cause significant mortality of zebra mussels and Asian clams (Corbicula fluminea Müller, 1774) (Elzinga and Butzlaff 1994;McMahon et al. 1995;Payne et al. 1998). Despite promising results from these earlier studies, CO 2 was not pursued as an aquatic invasive species (AIS) control tool until recent studies on its use to deter fish (Kates et al. 2012;Cupp et al. 2016) and as a biocide for bullfrogs (Abbey-Lambertz et al. 2014), New Zealand mud snails (Potamopyrgus antipodarum Gray, 1853) (Nielson et al. 2012), and nuisance fish (Cupp et al. 2017). Carbon dioxide offers several advantages over other molluscicides because it does not persist in the environment and can be readily off-gassed when a treatment is complete. ...
... The effects of CO 2 on burial could expose juveniles to predation, as well as displacement. Mobile species, such as fish (Clingerman et al. 2007;Kates et al. 2012;Cupp et al. 2017) and crayfish (Bierbower and Cooper 2010), can avoid areas of elevated PCO 2 . Although more subtle, the response of infaunal bivalves to CO 2 is similar and includes reduced burrowing and increased dispersal (Clements and Hunt 2015; . ...
Article
Abstract Control technology for dreissenid mussels (Dreissena polymorpha and D. bugensis) currently relies heavily on chemical molluscicides that can be both costly and ecologically harmful. There is a need for more environmentally neutral tools to manage dreissenid mussels, particularly in cooler water. Carbon dioxide (CO2) has been shown to be lethal to several species of invasive bivalves, including zebra mussels and Asian clams (Corbicula fluminea). We evaluated the effectiveness of unpressurized infusion of CO2 for 24 to 96 h (100 000–300 000 μatm PCO2) at a water temperature of 12 °C on mortality, byssal thread formation, and attachment of zebra mussels. The safety of elevated CO2 to a nontarget native freshwater mussel (Fatmucket, Lampsilis siliquoidea) was also determined. Elevated PCO2 exposure induced narcotization and reduced attachment of zebra mussels within 24 h. Mortality increased with exposure duration and PCO2. An estimated LT50 (lethal time to produce 50% mortality) for fixed PCO2 ranged from 24 h at 275 000 μatm to ~ 96 h at 100 000 μatm. Exposure of zebra mussels to CO2 for 96 h caused 80–100% mortality at all treatment levels. Fatmucket juveniles survived all PCO2 treatments but burial and byssal thread production were adversely affected during exposure. Our results demonstrate that CO2 is a viable option for management of zebra mussels in cool water and may have less adverse effect for native lampsiline mussels than current-use molluscicides. Key words: invasive species, dreissenid, unionid, elevated PCO2, toxicity, sublethal effects
... Carbon dioxide was first tested as a molluscicide in 1995 and found to effectively reduce attachment of zebra mussels (McMahon et al. 1995;Payne et al. 1998) and cause significant mortality of zebra mussels and Asian clams (Corbicula fluminea Müller, 1774) (Elzinga and Butzlaff 1994;McMahon et al. 1995;Payne et al. 1998). Despite promising results from these earlier studies, CO 2 was not pursued as an aquatic invasive species (AIS) control tool until recent studies on its use to deter fish (Kates et al. 2012;Cupp et al. 2016) and as a biocide for bullfrogs (Abbey-Lambertz et al. 2014), New Zealand mud snails (Potamopyrgus antipodarum Gray, 1853) (Nielson et al. 2012), and nuisance fish (Cupp et al. 2017). Carbon dioxide offers several advantages over other molluscicides because it does not persist in the environment and can be readily off-gassed when a treatment is complete. ...
... The effects of CO 2 on burial could expose juveniles to predation, as well as displacement. Mobile species, such as fish (Clingerman et al. 2007;Kates et al. 2012;Cupp et al. 2017) and crayfish (Bierbower and Cooper 2010), can avoid areas of elevated PCO 2 . Although more subtle, the response of infaunal bivalves to CO 2 is similar and includes reduced burrowing and increased dispersal (Clements and Hunt 2015; . ...
Full-text available
Article
Control technology for dreissenid mussels (Dreissena polymorpha and D. bugensis) currently relies heavily on chemical molluscicides that can be both costly and ecologically harmful. There is a need for more environmentally neutral tools to manage dreissenid mussels, particularly in cooler water. Carbon dioxide (CO 2 ) has been shown to be lethal to several species of invasive bivalves, including zebra mussels and Asian clams (Corbicula fluminea). We evaluated the effectiveness of unpressurized infusion of CO 2 for 24 to 96 h (100 000-300 000 μatm PCO 2 ) at a water temperature of 12 °C on mortality, byssal thread formation, and attachment of zebra mussels. The safety of elevated CO 2 to a nontarget native freshwater mussel (Fatmucket, Lampsilis siliquoidea) was also determined. Elevated PCO 2 exposure induced narcotization and reduced attachment of zebra mussels within 24 h. Mortality increased with exposure duration and PCO 2 . An estimated LT50 (lethal time to produce 50% mortality) for fixed PCO 2 ranged from 24 h at 275 000 μatm to ~ 96 h at 100 000 μatm. Exposure of zebra mussels to CO 2 for 96 h caused 80-100% mortality at all treatment levels. Fatmucket juveniles survived all PCO 2 treatments but burial and byssal thread production were adversely affected during exposure. Our results demonstrate that CO 2 is a viable option for management of zebra mussels in cool water and may have less adverse effect for native lampsiline mussels than current-use molluscicides.
... Some features are key elements in the successful establishment of a non-native species, especially among fish: short lifetime but with rapid growth and sexual maturation, high fertility rates and wide physiological tolerance or genetic variability and phenotypic plasticity Kates et al., 2012;. In addition, it is suggested that climate change could facilitate the invasion of non-native species increasing its impact on natural communities, favouring their reproduction and recruitment, by changing the discharge of rivers, increasing the water temperature, increasing the frequency of floods and severe droughts (Britton et al., 2010;Copp, 2006;Hellmann et al., 2008;. ...
... Examples are air bubble curtains, acoustic, electric or carbon dioxide barriers, among others, or combinations, with variable results (Kates et al., 2012;Zielinski et al., 2014). However, the mechanisms that usually prevent the dispersion of the majority of fish, native or non-native, and the studies behind the application and monitoring of these systems have been mostly focused on their behavioural responses, such as avoidance behaviour, rather than on their physiological impact. ...
... They are generally designed to exceed the target fishes' ability to swim, jump or climb past the structure in order to manage their spread through the river network or into critical habitats. A key motivation for the use of such barriers is that preventing invasion by undesirable species is generally a more efficient management strategy than trying to eliminate a species after introduction ( Kates et al. 2012). Design of intentional built barriers is the focus of this section. ...
... While non-physical intentional barriers have been implemented internationally and in a few cases in New Zealand, experience to date suggests results have been somewhat mixed with generally low success (e.g. Bullen and Carlson 2003;Kates et al. 2012;Noatch and Suski 2012;Charters 2013;Ryder 2015). Generally, they can only be relied on when partial exclusion is acceptable and often need to be used in combination with intentional physical barriers to improve their effectiveness . ...
... Several studies have demonstrated that CO 2 concentrations of 60 to 120 mg·L -1 (24 000 to 75 000 atm partial pressure of CO 2 (PCO 2 ); 1 atm = 101.325 kPa) would induce avoidance responses in fish and could be used to corral and harvest fish in a confined area or deter upstream migration through a stream or lock channel (Kates et al. 2012;Dennis et al. 2016;Cupp et al. 2017). Before its widespread deployment in AIS programs, the effects of elevated CO 2 on native species must be considered. ...
... Combined with the unburying and gaping behavior we observed, this can lead to increased predation and displacement by water currents. Carbon dioxide application also may reduce mussel reproduction by causing avoidance behaviors in fish host species (Ross et al. 2001;Clingerman et al. 2007;Kates et al. 2012), which are required for transformation of the parasitic larval (glochidia) stage. ...
Article
Levels of carbon dioxide (CO2) that have been proposed for aquatic invasive species control (24 000 – 96 000 μatm partial pressure of CO2 (PCO2); 1 atm = 101.325 kPa) were tested on two juvenile mussels, the fatmucket (Lampsilis siliquoidea) and the US federally endangered Higgins’ eye (Lampsilis higginsii). A suite of responses (survival, growth, behavior, and gene expres-sion) were measured after 28 days of exposure to CO2 and 14 days postexposure. The 28-day LC20 (concentration lethal to 20% of organisms) was lower for L. higginsii (31 800 μatm PCO2, 95% confidence interval (CI) 15 000 – 42 800 μatm) than for L. siliquoidea (58 200 μatm PCO2, 95% CI 45 200 – 68 100 μatm). Treatment-related reductions occurred in all measures of growth and condition. Expression of chitin synthase, key for shell formation, was downregulated at 28 days of exposure. Carbon dioxide caused narcotization and movement to the substrate surface of mussels, behaviors that could increase mortality by predation and displacement. We conclude that survival and growth of juvenile mussels could be reduced by continuous exposure to elevated CO2, but recovery may be possible with shorter-duration exposure.
... pCO 2 exposure treatments In the treatment tanks (379 l for fathead minnows and 227 l for silver carp), fish were exposed to one of three different CO 2 treatments: control (ambient) (&750), low pCO 2 (&1500) and high pCO 2 (&7500 latm.; Supplementary Table S1). These treatment levels were chosen because (a) Kates et al. (2012) found that shortterm exposure to 70 mg/l of CO 2 (&150,000 latm.) altered ventilation rates and caused behaviors indicative of 'stress' (e.g., surface ventilations, coughing, loss of equilibrium) suggesting that a holding level below 150,000 latm. ...
... A reduced alarm cue response after exposure to elevated CO 2 has many implications for management and the ecology of freshwater fish species. Freshwater fishes may be exposed to elevated pCO 2 due to natural environmental variation (reviewed by Hasler et al. 2016), climate change (Phillips et al. 2015), hatchery rearing (Colt and Orwicz 1991) and zones of elevated pCO 2 deployed as fish barriers (Kates et al. 2012;Noatch and Suski 2012). If fathead minnows were subjected to an increase in pCO 2 concentrations, they may lose their ability to appropriately respond to conspecific alarm cues such as skin extracts from a predator event. ...
... Following completion of the first set of tests, the pCO 2 in the common holding tank was raised to 8300 ± 400 atm (mean ± s.d.) for 5 days. This holding duration and pCO 2 were chosen as a 4 day holding period at 850 atm pCO 2 has elicited changes in the behaviour of marine fishes and an extended exposure of L. macrochirus to this pCO 2 caused physiological changes, but not a loss in equilibrium as fishes lose equilibrium at high levels of CO 2 (Kates et al., 2012). Chosen pCO 2 levels were held constant throughout the experiment using a Pinpoint pH Regulator Kit (American Marine Inc.; www.americanmarineusa.com) ...
... In the context of exposure to elevated pCO 2 for freshwater fishes, results of the present study have a number of implications for fisheries management and ecology. Freshwater fishes have potential to be exposed to elevated pCO 2 due to natural environmental variation (Hasler et al., 2016), climate change (Phillips et al., 2015), hatchery rearing (Colt & Orwicz, 1991) and zones of elevated pCO 2 deployed as fish barriers (Kates et al., 2012;. If a freshwater species such as L. macrochirus is exposed to sufficiently high pCO 2 for extended periods of time, data from the current study indicate that lateralization and boldness may not be altered, but there may be an increase in activity and velocity of up to 30%, resulting in additional swimming activity and higher energetic costs (Jobling, 1995). ...
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Article
The current study investigated the behavioural response of Lepomis macrochirus following exposures to elevated carbon dioxide (CO2 ). For this, L. macrochirus were held at ambient pCO2 (160 μatm pCO2 ) for 7 days, then exposed to elevated pCO2 (8300 μatm pCO2 ) for 5 days, and then returned to ambient conditions for a further 5 days to recover. At the end of each exposure period, several behavioural metrics were quantified (boldness, lateralization and activity). Data showed no change in lateralization and most metrics associated with performance and boldness. During the boldness test, however, average velocity, velocity in the thigmotaxis (outer) zone and proportion of activity in the thigmotaxis zone increased with pCO2 exposure. During post-exposure, average velocity of L. macrochirus decreased. In addition, individual rank was repeatable during the pre-exposure and post-exposure period in three of the 17 metrics investigated (average velocity in the middle zone, average velocity near object and total shuttles to the object zone), but not during the CO2 exposure period, suggesting that elevated pCO2 disrupted some behavioural performances. Overall, this study found elevated pCO2 caused disruption to behaviours of freshwater fishes such as L. macrochirus and effects do not appear to be as serious as has been shown for marine fishes.
... 3100 μatm; 1 kPa ≈ 10,000 μatm ≈ 1% ≈ 7.5 Torr ≈ 7.5 mmHg) (Cole et al., 1994;Hasler et al., 2016;Park et al., 1969;Raymond et al., 2013) due to a number of factors including microbial respiration, high biomass, presence of carbonate deposits, and the physicochemical properties of CO 2 . For example, PCO 2 may reach values as high as 2-8 kPa in tropical systems (Cole et al., 1994;Li et al., 2013;de Rasera et al., 2013), 2-4 kPa in aquaculture ponds (Damsgaard et al., 2015), 0.5-2 kPa (10-40 mg L − 1 ) in recirculating aquaculture systems , 4.7 kPa (55 mg L − 1 ) during fish transport (Allred et al., 2020), and 5-11 kPa (100-200 mg L − 1 ) where CO 2 is used as a chemical barrier against invasive species (Donaldson et al., 2016;Kates et al., 2012). Fish often have adverse responses to elevated CO 2 (hypercapnia) that can disrupt acid-base homeostasis of blood and tissues Shartau et al., 2020;Shartau et al., 2019), and cause maladaptive behavioral responses (Heuer et al., 2019;Ou et al., 2015;Regan et al., 2016) which may limit their tolerance to hypercapnia . ...
Article
High CO2 (hypercapnia) can impose significant physiological challenges associated with acid-base regulation in fishes, impairing whole animal performance and survival. Unlike other environmental conditions such as temperature and O2, the acute CO2 tolerance thresholds of fishes are not understood. While some fish species are highly tolerant, the extent of acute CO2 tolerance and the associated physiological and ecological traits remain largely unknown. To investigate this, we used a recently developed ramping assay, termed the Carbon Dioxide maximum (CDmax), that increases CO2 exposure until loss of equilibrium (LOE) is observed. We investigated if there was a relationship between CO2 tolerance and the Root effect, β-adrenergic sodium proton exchanger (βNHE), air-breathing, and fish habitat in 17 species. We hypothesized that CO2 tolerance would be higher in fishes that lack both a Root effect and βNHE, breathe air, and reside in tropical habitats. Our results showed that CDmax ranged from 2.7 to 26.7 kPa, while LOE was never reached in four species at the maximum PCO2 we could measure (26.7 kPa); CO2 tolerance was only associated with air-breathing, but not the presence of a Root effect or a red blood cell (RBC) βNHE, or fish habitat. This study demonstrates that the diverse group of fishes investigated here are incredibly tolerant of CO2 and that although this tolerance is associated with air-breathing, further investigations are required to understand the basis for CO2 tolerance.
... Changes in habitat availability associated with flood contraction are known to influence the chemical environment (e.g., increased water temperatures, decreased DO concentrations and altered soil-nutrient dynamics; Malard et al., 2000), potentially favouring behaviourslike emigration-intended to increase survival as habitat availability and quality continue to deteriorate. Others have linked lateral fish movements between river-floodplain ecosystems to changes in water temperature with little influence from other water-quality parameters (Hohausová et al., 2003;Nunn et al., 2010), but changes in other water-quality parameters that challenge an individual's physiological performance or survival could induce behavioural avoidance of low-quality habitats and increase movement among habitats (Kates et al., 2012). Phenology of fish emigration can be complex, and some researchers have found patterns related to body size (reviewed by Welcomme, 1979) while others have not (Kwak, 1988). ...
Article
Floods play an important role in regulating ecological patterns and processes in river–floodplain ecosystems. Yet, the hydrologic connectivity between many river–floodplain ecosystems has been severed by anthropogenic activities that have markedly altered these ecological processes. Superimposed over anthropogenic reductions in river–floodplain connectivity, climate change is also shifting flood characteristics to produce more intense, unpredictable floods. To more efficiently manage river–floodplain ecosystems, additional research characterising the ecological consequences of unpredictable floods on fish movements is required. In this study, we used a modified fyke net to characterise the patterns and identify the important drivers of lateral movements of fish emigrating from the floodplain during contraction of a high‐magnitude, late‐summer flood in the Fourche LaFave River, Arkansas, in 2007. We captured approximately 43,200 fish emigrating from the floodplain over an 8‐day period, representing 38 distinct species from 12 families. We related fish‐emigration patterns to different stages of flood contraction and linked species‐specific emigration to water‐level fluctuations and associated changes in floodplain habitat availability and quality. We also show that some species exhibit body‐size emigration patterns, where larger individuals emigrated from the floodplain earlier than smaller individuals. To meet conservation goals for maintaining healthy riverine ecosystems and the biodiversity they support, it will be necessary to continue characterising and identifying the ecological consequences of shifting flood characteristics within river–floodplain ecosystems.
... For example, specifically designed sound profiles that match hearing sensitivities of the target species have shown promise for deterring movement of the bigheaded carp in laboratory flumes (Dennis et al. 2019). DGS that employ carbon dioxide have also been pursued and showed relatively high efficiency for several species of fish in laboratory tanks and ponds (Donaldson et al. 2016;Kates et al. 2012). However, while the effectiveness of DGS technologies based on sound, light and carbon dioxide has shown good results (often > 90% deterrence) in laboratory tanks, pond, and mesocosms, these technologies have rarely been tested under natural field conditions and the results of these tests were mixed. ...
... Carbon dioxide has demonstrated effectiveness as a control for a variety of aquatic invasive species (AIS) including dreissenid mussels (McMahon et al. 1995;Waller and Bartsch 2018;Waller et al. 2020), invasive Asian carp (Hypophthalmichthys spp.) (Kates et al. 2012;Cupp et al. 2017bCupp et al. , c, 2018, bullfrogs (Lithobates catesbeianus) (Abbey-Lambertz et al. 2014), round goby (Neogobius melanostomus) (Cupp et al. 2017a), New Zealand mud snails (Potamopyrgus antipodarum) (Nielson et al. 2012), and invasive crayfishes (red swamp crayfish, Procambarus clarkii and rusty crayfish, Faxonius rusticus) (Fredricks et al. 2020). Carbon dioxide is easily off-gassed, has low risk to human health, is widely available, can be repurposed from industrial sources and is inexpensive (Treanor et al. 2017). ...
... Recently, there has been the development and limited deployment of novel technologies for controlling invasive species and restricting their spread through freshwater ecosystems. These include bio-bullets (BioBullets 1 ), which target filter-feeding biofouling organisms in industrial settings, electric barriers to deter spread of aquatic organisms (Sparks et al., 2010;Benejam et al., 2015;Kim and Mandrak, 2017), and more recently the suggestion that water saturated with carbon dioxide could be used to inhibit the spread of invasive organisms (Kates et al., 2012;Treanor et al., 2017;Suski, 2020). While these technologies each offer promise, more research is needed to understand how effective they are at deterring spread of a range of nonnative species. ...
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Canals and other connected waterway systems, including the Chicago Area Waterway System (CAWS), have often facilitated the spread of non-native species. Electric barriers have recently emerged as a method for preventing this spread and protecting uninvaded ecosystems from new invaders. The largest system of electric barriers in the world is in the CAWS and is operated primarily to prevent the spread of invasive Asian carp. It is not known whether these barriers are effective for other species, particularly invasive invertebrates. Here, we provide data regarding the efficacy of an electric field that operates at the same parameters as the electric barrier in the CAWS in affecting behaviors of two invertebrate species, the red swamp crayfish Procambarus clarkii and the amphipod Hyalella azteca. We constructed an electric field within a tank that operates at the same parameters as the existing CAWS barriers and determined the effects of the electric field on our test species. At the electric field parameters of the CAWS barriers, the vast majority of P. clarkii individuals showed altered movement with maintained equilibrium. For H. azteca, behavioral responses were less extreme than for P. clarkii, with a majority of individuals experiencing altered movement. By measuring the orientation of organisms to the electric field, we determined that the test organisms are affected by the electric field, especially at lower field strengths where they exhibited no or little other behavioral response. At lower field strengths, P. clarkii exhibited changes in orientation, but at higher field strengths, individuals were less able to orient themselves. H. azteca exhibited changes in orientation to the electric field at all field strengths. The results of this study suggest that the existing electric barriers may not slow or prevent spread of invasive invertebrates—including amphipods and crayfish—through passive movement attached boats/barges or through downstream drift, but that the barriers may prevent spread by active upstream movement. Overall, our work gives new data regarding the efficacy of electric fields in preventing the spread of invasive invertebrates and can inform management decisions regarding current and future electric barriers in the CAWS.
... Various behavioral systems based on the use of sensory stimuli has been studied by several researchers with the objective to deter movements and protect fish from hydraulic traps as well as to increase the efficiency of transposition systems, through acoustic stimuli [18][19][20], luminous [21][22][23][24], electrical [25,26] chemical [27,28] among other systems. The effectiveness of these different stimuli is varied and depend essentially on the sensitive capacities of the species for a given stimulus, which may be related to their internal/external morphology, trophic chain, reproduction, or also related to environmental conditions [29,30]. ...
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The use of non-physical barriers, particularly based on acoustic and luminous stimuli has been historically used to influence the behavior of fish, mainly for fishing purposes. Nowadays, behavioral barriers and guidance systems have been developed, not only to deter movements of fish, but also to promote behavioral responses with the objective of native fish protection, in particular the potamodromous species, reducing their mortality in the hydraulic structures of dams and guiding them towards transposition systems or to replacement habitats in regularized water bodies. This review details the use of acoustic and luminous systems and their evolution in recent years (Scopus 2012–2019) for the development of selective behavioral barriers for fish. We found that recent technologies try to identify new acoustic and luminous sensory ranges. Ambient sound, sound of predators or luminous spectral bands with different wavelengths have been used to selectively stimulate target and non-target species, in order to improve the effectiveness of repulsive/attractive systems for fish. Guidelines for future research in the area are also present.
... A variety of specialized "lures," glochidial packets (conglutinates), and behaviors have evolved in each unionid species to attract a host fish to the female, increasing the likelihood of successful glochidial attachment to the host (McMahon 1991;Haag 2012). Carbon dioxide is an effective deterrent for fish (Clingerman et al. 2007;Kates et al. 2012;Dennis et al. 2015) and could disrupt the interaction of mussel and host fish during the glochidial release period. Behavioral responses (i.e., gaping and unburial) of juveniles to CO 2 were more frequent at 20°C compared to 5°C and could also increase their risk of predation or displacement. ...
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Zebra mussels (Dreissena polymorpha) have exacerbated the decline of native freshwater mussels (Order Unionida) in North America since their arrival in the 1980s. Options for controlling invasive mussels, particularly in unionid mussel habitats, are limited. Previously, carbon dioxide (CO2) showed selective toxicity for zebra mussels, relative to unionids, when applied in cool water (12 °C). We first determined 96‐h lethal concentrations of CO2 at 5 and 20 °C to zebra mussels and responses of juvenile plain pocketbook (Lampsilis cardium). Next, we compared the time to lethality for zebra mussels at 5, 12, and 20 °C during exposure to partial pressure of CO2 (PCO2) 110–120 atmospheres (atm; 1 atm = 101.325 kPa) and responses of juvenile plain pocketbook and fragile papershell (Leptodea fragilis). We found efficacious CO2 treatment regimens at each temperature that were minimally lethal to unionids. At 5 °C, plain pocketbook survived 96 h exposure to the highest PCO2 treatment (139 atm). At 20 °C, the 96 h LC10 (lethal concentration to 10% of animals) for plain pocketbook [173 atm PCO2, 95% confidence interval (CL) 147–198 atm] was higher than the LC99 for zebra mussels (118 atm PCO2, CL 109–127 atm). Lethal time to 99% mortality (LT99) of zebra mussels in 110 to 120 atm PCO2 ranged from 100 h at 20 °C to 300 h at 5 °C. Mean survival of both plain pocketbook and fragile papershell juveniles exceeded 85% in LT99 CO2 treatments at all temperatures. Short‐term infusion of 100 to 200 atm PCO2 at a range of water temperatures could reduce biofouling by zebra mussels with limited adverse effects on unionid mussels. This article is protected by copyright. All rights reserved.
... This was contrasted to the control treatment pH of 8.2 that laboratory stock populations had become adapted to over several generations since their initial collection in -2009(Nilsson, Lundbäck, Postavnicheva-Harri, & Persson, 2011. pH for the acidified treatment was maintained by an Aqua Medic ® CO 2 computer coupled with a solenoid valve and multi-pH probe (Hasler, Midway, et al., 2016;Kates, Dennis, Noatch, & Suski, 2012;Midway et al., 2017). This was set to a threshold of 6.52, above which the solenoid valve would open and CO 2 gas would bubble through the treatment tank until a pH of 6.50 was achieved. ...
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Abstract Rising atmospheric carbon dioxide levels are driving decreases in aquatic pH. As a result, there has been a surge in the number of studies examining the impact of acidification on aquatic fauna over the past decade. Thus far, both positive and negative impacts on the growth of fish have been reported, creating a disparity in results. Food availability and single‐generation exposure have been proposed as some of the reasons for these variable results, where unrealistically high food treatments lead to fish overcoming the energetic costs associated with acclimating to decreased pH. Likewise, exposure of fish to lower pH for only one generation may not capture the likely ecological response to acidification that wild populations might experience over two or more generations. Here we compare somatic growth rates of laboratory populations of the Trinidadian guppy (Poecilia reticulata) exposed to pH levels that represent the average and lowest levels observed in streams in its native range. Specifically, we test the role of maternal acclimation and resource availability on the response of freshwater fishes to acidification. Acidification had a negative impact on growth at more natural, low food treatments. With high food availability, fish whose mothers were acclimated to the acidified treatment showed no reduction in growth, compared to controls. Compensatory growth was observed in both control–acidified (maternal–natal environment) and acidified–control groups, where fish that did not experience intergenerational effects achieved the same size in response to acidification as those that did, after an initial period of stunted growth. These results suggest that future studies on the effects of shifting mean of aquatic pH on fishes should take account of intergenerational effects and compensatory growth, as otherwise effects of acidification may be overestimated.
... Although results are promising for use with sea lamprey, it is important to understand that CO 2 deterrents or barriers are not species-specific. Kates et al. (2012) found that invasive silver and bighead carps, bluegill (Lepomis macrochirus), and largemouth bass (Micropterus salmoides) all avoided areas with CO 2 above 100 mg/L. Before CO 2 can be utilized as a nonphysical barrier tool for sea lamprey control, concerns over non-target impacts, water acidification, cost of CO 2 production, and regulatory permission (i.e. ...
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Currently, application of lampricides and installation of low-head barriers are the only proven means of sea lamprey (Petromyzon marinus) control in the Great Lakes. While sea lamprey cannot climb or jump over low-head barriers, many desirable migratory species also cannot traverse barriers and are unintentionally blocked. Recently, there has been a push to reduce reliance on chemical controls as well as increase stream connectivity and flood con-veyance. In response, the Great Lakes Fishery Commission (GLFC) continues to seek alternative methods of control. Great Lakes basin resource managers often request consideration of alternatives to both lampricide use and low-head barriers. Seasonal operation and alternative barrier designs (e.g. velocity barriers and electrical barriers) that incorporate additional features such as selective fish passage or flood conveyance are among the most commonly requested options. To date, alternative barrier technologies have been intermittently successful in the sea lamprey control program directed by the GLFC, yet continue to be proposed as alternatives to conventional low-head barriers. This document provides a comprehensive review on the current state of knowledge regarding the effectiveness of current and alternative barrier technologies and their historical use in the sea lamprey control program. This synthesis provides resource managers and sea lamprey control agents a reference and some tools to facilitate decision making around barriers that balance the critical need for invasive species control and fishery restoration.
... In comparison, nonphysical barriers use behavioural stimuli to divert fishes and may be species specific in some instances . Nonphysical barriers have been developed and deployed to exclude fishes from undesirable locations using a combination of electricity, sound, strobe light, bubbles, carbon dioxide, electricity, and pulse pressure (Maes et al., 2004;Noatch and Suski, 2012;Kates et al., 2012;Ruebush et al., 2012;Romine et al., 2015;Vetter et al., 2015Vetter et al., , 2017ACRCC, 2017;Zielinski and Sorensen, 2017). ...
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https://www.tandfonline.com/doi/full/10.1080/14634988.2019.1624135?needAccess=true#metrics-content When dealing with invasive fishes, permanent barriers may inhibit spread, but may not be feasible due to costs and logistical constraints. Alternatively, non-permanent barriers using electricity, light, sound, pressure, bubbles, and CO2 are being developed and deployed in efforts to limit and prevent the spread of aquatic invasive species or to achieve fish guidance and conservation. However, the effectiveness of these barriers is quite variable and testing is often lacking for both invasive and native species. We conducted a laboratory experiment to investigate the impact of vertical electric barrier on behaviour of Rainbow Trout, Oncorhynchus mykiss. In response to electric current, Rainbow Trout responded by significantly decreasing passage through the electric barrier zone and spending more time away from the electric barrier when it was turned on during the stimulus period compared to pre-stimulus period. Moreover, when interacting with electric barrier, Rainbow Trout exhibited certain behaviours (e.g. stunned and remained on the same side of the barrier, stunned and crossed the barrier) more than others (e.g. approach and retreat, deflected, and paralyzed). Moreover, it appears that Rainbow Trout remained distant from the electric barrier even after the electric barrier was turned off. Our results indicate that relatively weak electric gradient (i.e. voltage gradient: 0.2 – 0.4 v·cm⁻¹, power density: 3 – 42 µW·cm⁻³) can inhibit the movement of Rainbow Trout. Our results also highlight the importance of detailed investigation of behavioural responses of target species when evaluating and considering fish-deterrent or guidance technologies.
... Non-physical barriers can use behavioral and/or physiological stimuli to control fish movements, since fish may exhibit attraction or repulsion behavior, caused by various environmental stimuli including sound [15,22,23], light [20,21,24,25], electric [26,27], chemical [28,29], and mixed [30,31]). The efficiency of these non-physical barriers depends on the fish species, the environmental conditions, and the potential habituation to a particular stimulus [32,33]. ...
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A repulsive effect, that some induced primary stimuli, like sound and light, is known to be provoked in fish behavior. In the present study, two strobe light frequencies, 350 flashes/minute and 600 flashes/minute, were tested in laboratorial conditions, using three native freshwater fish species of northern Portugal: Brown trout (Salmo trutta), Northern straight-mouth nase (Pseudochondrostoma duriense) and Iberian barbel (Luciobarbus bocagei). The results showed a differential repulsive behavior of the fish species to light stimulus, and particularly to a frequency of 600 flashes/minute. S. trutta presented the most repulsive behavior, whereas the L. bocagei showed less repulsion to the light stimulus. No relevant differences were found between pre-test and post-assessments, confirming a rapid recovery of natural fish behavior after the deterrent effect. The results highlighted the potential of behavioral barriers, particularly in salmonid streams, based on strobe light stimulus.
... Chemical delivery is critical during piscicide treatments to ensure that target organisms are exposed to a lethal dose. Carbon dioxide is commonly administered on small scales using liquid or compressed-gas storage tanks and submerged air supply lines with porous diffusers (Kates et al. 2012;Cupp et al. 2017b). However, injecting CO 2 via aeration is more challenging at larger field scales due to limited site access (e.g., remote lakes) with large CO 2 trailers, potential freezing of delivery lines, and limited treatment distribution. ...
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Few chemicals are approved to control or eradicate nuisance fish populations in the United States. Carbon dioxide (CO2) is currently being developed and studied as a new piscicide option for non‐selective population control. This study evaluated dry ice (solid state CO2) as a simple CO2 delivery method during winter piscicide applications. Non‐native Silver Carp Hypophthalmichthys molitrix, Bighead Carp Hypophthalmichthys nobilis, and native Fathead Minnow Pimephales promelas were overwintered together in ice‐covered ponds treated with 25 kg dry ice/100,000 L (low treatment) or 50 kg dry ice/100,000 L (high treatment). Overwinter fish survival was significantly reduced in dry ice treated ponds relative to untreated control ponds. Fathead Minnow were less susceptible to CO2 exposure, with 26–96% survival in low treatment ponds and 4–68% survival in high treatment ponds. Silver Carp and Bighead Carp were more sensitive to CO2 treatments and no individuals of either species survived in ponds with the high treatment level. Water samples were also collected in all ponds throughout this study and we observed notably higher Silver Carp and Bighead Carp eDNA concentrations in dry ice treated ponds relative to untreated control ponds. Distinct changes in eDNA trends correlated with fish mortality and results suggest that eDNA sampling could be a useful indicator of piscicide efficacy. This study demonstrates that CO2 administered as dry ice is an effective under‐ice piscicide method. This article is protected by copyright. All rights reserved.
... Clearly, further research is required to determine the generality and repeatability of CO 2 -associated behavioural and sensory impairments in coral-reef fishes. The effects of CO 2 on fish behaviour are of fundamental interest to fish biology and may have some useful applications (Donaldson et al., 2016;Kates et al., 2012). More broadly, in the context of OA, there is a need for experiments with longer acclimation times (Sundin et al., 2017;Welch et al., 2014) and that are designed to assess the effects of ecologically relevant combinations of elevated temperature and CO 2 , given that these two factors are changing in tandem in the real world (Hughes et al., 2017). ...
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Adult bluespotted rockcod Cephalopholis cyanostigma, a coral‐reef grouper, were acclimated to either ambient (mean ± S.D. 41.12 ± 2.13 Pa;) or high pCO2 (95.75 ± 11.75 Pa) conditions in a laboratory for 8–9 days, then released at the water surface directly above a reef (depth c. 5 m) and followed on video camera (for 191 ± 21 s) by scuba divers until they sought cover in the reef. No differences were detected between groups in any of the six measured variables, which included the time fish spent immobile after release, tail beat frequency during swimming and the time required to locate and enter the protective shelter of the reef. This article is protected by copyright. All rights reserved.
... In contrast, nonphysical barriers use behavioural or physiological stimuli to divert fishes and may be species specific in some instances (e.g., Schilt 2007;Noatch and Suski 2012). A variety of nonphysical barriers have been developed and deployed to exclude fishes from undesirable locations using a combination of sound, strobe light, bubble, carbon dioxide, electricity, and pulse pressure (Maes et al. 2004;Noatch and Suski 2012;Kates et al. 2012;Ruebush et al. 2012;Vetter et al. 2015). ...
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http://rdcu.be/uW3Y When dealing with invasive fishes, permanent barriers may be best in preventing spread; however, they may not be feasible due to various costs and/or logistical constraints. Alternatively, various non-permanent barriers using electricity, light, sound, pressure, bubbles, and CO2 are being developed and deployed in efforts to limit the spread of aquatic invasive species or to achieve fish guidance and conservation. However, the effectiveness of these barriers is quite variable, and testing is often lacking for both target and non-target species. We conducted a series of laboratory trials to examine the effects of strobe light on behaviour of Common Carp, Brown Bullhead, and Largemouth Bass. In response to strobe lights, Common Carp and Brown Bullhead stayed significantly farther away compared to the control period and resumed their normal activity once the strobe light was turned off. This suggests that strobe lights may prove to be a useful fish deterrent in the field. Our results also highlight the importance of examining the response of both target and non-target species when evaluating fish deterrent technologies. https://link.springer.com/article/10.1007%2Fs10641-017-0653-7
... These regulatory mechanisms to buffer acidosis typically involve obtaining and retaining HCO 3 from the environment while excreting accumulated H ? (e.g., Cameron, 1978;Heisler et al., 1982;Busk et al., 1997;Brauner & Baker, 2009;Hannan et al., 2016a). In addition to buffering acidosis, many freshwater animals undergo a physiological stress response 123 following exposure to weakly acidified water (e.g., Kates et al., 2012;Dennis et al., 2015a, b;Hannan et al., 2016a, b, c;Jeffrey et al., 2016) which also requires energy (Beyers et al., 1999). Thus, the energetic costs associated with maintaining homeostasis in situations of chronic exposure to weak acidification can alter the finite energy budgets of freshwater animals, and consequently result in a reduction in growth rates, calcification, and body mass (e.g., Fivelstad et al., 2003Fivelstad et al., , 2007Hosfeld et al., 2008;Lopes-Lima et al., 2009;Good et al., 2010;Abbey-Lambertz et al., 2014;Fivelstad et al., 2015). ...
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Weak acidification can occur in freshwater ecosystems when free carbon dioxide (CO2) levels increase, which can happen for a variety of reasons. To define the state of knowledge for how weak acidification influences freshwater biota and ecosystems, a review of the primary literature was conducted. Despite few empirical studies focused on weak acidification in the primary literature (~100 studies), some themes have emerged from our literature review. Most studies focused on physiological responses at the organismal level, and fish were the most studied taxa. Animals exhibited reduced individual growth rates, and, in contrast, primary producers demonstrated increased individual and population growth rates. In animals, mortality, sub-lethal injuries, and changes to behaviours were also observed. Negative consequences to reproduction in macrophytes were found. Few studies have focused on population, community, or ecosystem levels, though broad scale studies suggest that weak acidification can limit species community diversity, specifically in invertebrates and fish. Moving forward, researchers need to continue to advance our understanding of the consequences of weak acidification for freshwater biota. Furthermore, priority should be placed on research that can evaluate the potential for weak acidification in freshwater to lead to changes in ecological regimes or economical outcomes, such as fisheries collapses.
... Noatch and Suski 2012). A variety of nonphysical barriers have been developed and deployed to exclude fishes from undesirable locations using a combination of electricity, sound, strobe light, bubble, carbon dioxide, electricity, and pulse pressure (Maes et al. 2004;Noatch and Suski 2012;Kates et al. 2012;Ruebush et al. 2012;Romine et al. 2015;Vetter et al. 2015;Murchy et al. 2017;Vetter et al. 2017;Kim and Mandrak in press). ...
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http://www.reabic.net/journals/mbi/2017/Accepted/MBI_2017_Kim_Mandrak_correctedproof.pdf When managing invasive fishes, permanent barriers may be best in preventing spread; however, they may not be feasible due to costs and logistical constraints. Alternatively, non-permanent barriers using electricity, light, sound, pressure, bubbles, CO2, and other stimuli are being developed and deployed in efforts to limit the spread of aquatic invasive species or to achieve fish guidance and conservation. However, the effectiveness of these barriers is quite variable and testing is often lacking for both target and non-target species. We conducted a series of laboratory trials to examine the effects of a vertical electric barrier on behaviour of common carp Cyprinus carpio (Linnaeus, 1758). In response to the electric field, common carp reduced passing the electric barrier significantly, exhibiting different behaviours when interacting with the electric barrier, and spent more time away from the electric barrier when it was turned on during the stimulus period compared to pre- and post-stimulus periods. Our results suggest that a relatively weak electric gradient (i.e., voltage gradient: 0.2–0.4 V·cm-1, power density: 3–42 μW·cm-3) can inhibit the movement of common carp. Our results also highlight the importance of detailed examination of behavioural responses of target species when evaluating and considering fish-deterrent technologies.
... Freshwater fishes respond negatively to elevated Pco 2 and show high individual variation in the magnitude of their behavioral and physiological responses. For example, shuttling away from elevated Pco 2 of three freshwater species showed considerable within-species variation (threefold difference between minimum and maximum shuttling Pco 2 ; Kates et al. 2012) despite Pco 2 levels being found to cause a range of negative physiological responses (Dennis et al. 2015). To assess within-species variation, determining the repeatability of a response to elevated Pco 2 is necessary, which specifically requires quantifying the proportion of the total variation among measurements within individuals (Wolak et al. 2012). ...
Article
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.
... In a review of 7000 global rivers and streams, the average median value for pCO 2 was~3100 µatm (Raymond et al., 2013) 1 679 ± 543 to 35 617 ± 46 757 µatm, with means in the USA ranging from 679 ± 543 to 9475 ± 993 µatm (Cole and Caraco, 2001). In addition to these natural sources of elevated pCO 2 , recent work has shown that zones of elevated CO 2 can act as non-physical fish barriers, thereby providing a management tool to prevent the movement and spread of invasive fish species (Kates et al., 2012;Noatch and Suski, 2012). Although a specific method for the use of CO 2 barriers to deter fish movement has not yet been defined, one potential application is the intermittent addition of CO 2 into a navigational lock or approach channel at vulnerable times (i.e. when lock doors are open; United States Army Corps of Engineers, 2014a), resulting in downstream pulses of CO 2 -rich water. ...
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Freshwater systems are at risk owing to increasing carbon dioxide (CO 2) 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 CO 2 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 pCO 2 (~1000 µatm) or intermittent conditions of pCO 2 (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 CO 2 , suggesting that the recovery time between CO 2 pulses (1.5 h) was not sufficient for recovery from the CO 2 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 pCO 2 (i.e. elevations in HCO 3 − , Ca 2+ , Na + and glucose, and decreases in Mg 2+ and Cl −). However, species differences were observed across almost all variables measured, which emphasizes the need for multispecies studies.
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Invasive carps are ecologically and economically problematic fish species in many large river basins in the United States and pose a threat to aquatic ecosystems throughout much of North America. Four species of invasive carps: black carp (Mylopharyngodon piceus), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis), are particularly concerning for native ecosystems because they occupy and disrupt a variety of food and habitat niches. In response, natural resource agencies are developing integrated pest management (IPM) plans to mitigate invasive carps. Control tools are one key component within a successful IPM program and have been a focal point for development by governmental agencies and academic researchers. For example, behavioral deterrents and barriers that block migratory pathways could limit carps range expansion into new areas, while efficient removal methods could suppress established carp populations. However, control tools are sometimes limited in practice due to uncertainty with deployment, efficacy and availability. This review provides an overview of several emerging modelling approaches and control technologies that could inform and support future invasive carp IPM programs.
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Bigheaded Carp have spread throughout the Mississippi River basin since the 1970s. Little has stopped the spread as carp have the ability to pass through locks and dams, and they are currently approaching the Great Lakes. However, the location of the leading edge in the Illinois River has stalled for over a decade, even though there is no barrier preventing further advancement towards the Great Lakes. Defining why carp are not moving towards the Great Lakes is important for predicting why they might advance in the future. The aim of this study was to test the hypothesis that anthropogenic contaminants in the Illinois River may be playing a role in preventing further upstream movement of Bigheaded Carp. Ninety three livers were collected from carp at several locations between May and October of 2018. Liver samples were analyzed using gas chromatography-mass spectrometry in a targeted metabolite profiling approach. Livers from carp at the leading edge had differences in energy use and metabolism, and suppression of protective mechanisms relative to downstream fish; differences were consistent across time. This body of work provides evidence that water quality is linked to carp movement in the Illinois River. As water quality in this region continues to improve, consideration of this impact on carp spread is essential to protect the Great Lakes.
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Barrier removal is a recognized solution for reversing river fragmentation, but restoring connectivity can have consequences for both desirable and undesirable species, resulting in a connectivity conundrum. Selectively passing desirable taxa while restricting the dispersal of undesirable taxa (selective connectivity) would solve many aspects of the connectivity conundrum. Selective connectivity is a technical challenge of sorting an assortment of things. Multiattribute sorting systems exist in other fields, although none have yet been devised for freely moving organisms within a river. We describe an approach to selective fish passage that integrates ecology and biology with engineering designs modeled after material recycling processes that mirror the stages of fish passage: approach, entry, passage, and fate. A key feature of this concept is the integration of multiple sorting processes each targeting a specific attribute. Leveraging concepts from other sectors to improve river ecosystem function may yield fast, reliable solutions to the connectivity conundrum.
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Technical Report
Les quatre espèces de carpe asiatique sont des espèces aquatiques envahissantes (EAE) qui représentent une menace sérieuse pour l’intégrité écologique du fleuve Saint-Laurent et de ses tributaires. Bien que nous considérons que la carpe de roseau (Ctenopharyngodon idella) fréquente les eaux du fleuve et de deux de ses tributaires, au moment de rédiger ce rapport, son niveau d’abondance est inconnu. Quant aux trois autres espèces, elles n’y ont pas été détectées à ce jour. Il est donc encore possible d’agir pour prévenir l’arrivée ou la dispersion de ces espèces dans les eaux intérieures. La protection de ces eaux est d’ailleurs un des objectifs du Programme québécois de lutte contre les carpes asiatiques. L’objectif du rapport est de procéder à une première évaluation des risques de dispersion des carpes asiatiques dans le fleuve Saint-Laurent et ses tributaires en considérant leur capacité pour franchir des obstacles artificiels et naturels entre le fleuve Saint-Laurent et l’amont des tributaires et, le cas échéant, d’évaluer les options pour freiner leur progression vers l’amont. L’évaluation des risques de dispersion implique aussi l’acquisition de connaissances sur les caractéristiques des habitats propices aux carpes asiatiques et de connaître leur capacité de nage. Ces aspects sont également traités dans le rapport. Finalement, certaines options de gestion liées notamment à la configuration des obstacles sont proposées.
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Individual animals differ in their responses to external stressors, and sociability has been shown to impact whether or not an individual will avoid a stressor. However, the effect of collective group behaviour on individual avoidance in response to a stressor has not been elucidated. In this study, we sought to determine whether stressor avoidance behaviour in individuals is affected by the behaviour of a familiar shoal, and if social personality is a driver of avoidance behaviour. Bluegill, Lepomis macrochirus, were exposed to either carbon dioxide or rising temperatures in a shuttle box choice tank. All bluegill were exposed to a stressor in isolation, then their social personalities were quantified using a social network assay. Bluegill were then exposed to the same stressor in the presence of a familiar shoal, with the entire shoal being able to respond to the stressor. We found that being in a shoal significantly decreased individual avoidance thresholds to both carbon dioxide and temperature, but neither avoidance behaviour in isolation nor individual social personality type was predictive of this response. The presence of the shoal was the primary driver of the difference in avoidance behaviour when bluegill were in isolation versus when they were in groups. Potential mechanisms, both behavioural and physiological, for the relationship between group behaviour and stressor avoidance are discussed. Our results provide evidence that group movements impact individual avoidance of stressors, which may have implications for the behaviour of animals in response to decreasing habitat quality.
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Challenging environmental conditions can induce voluntary behavioral avoidance in animals. Dissolved carbon dioxide (CO2) is an environmental stressor previously shown to upregulate the stress axis in fish, and also cause voluntary avoidance. Variation in individual state or context, such as whether an animal is fasted or fed, can alter animal behavior, including the response to environmental challenges. The current study sought to define the influence of nutritional status on the response of Largemouth Bass to elevated CO2. Two groups of Largemouth Bass, one that was fed and one that was fasted, were first subjected to a CO2 shuttling protocol to define avoidance thresholds, followed by a CO2 tolerance protocol to define the time required to lose equilibrium and recover. Data showed that, while feeding and fasting had no influence on avoidance of CO2, fasted fish required 17% longer to lose equilibrium in elevated CO2. Avoidance of elevated CO2 is therefore independent of animal state, but fish in poor nutritional condition from fasting are more tolerant. Therefore, managers considering elevated CO2 as a non‐physical barrier to deter fish movements should be cognizant of food availability for as fasted animals may require increased partial pressures of CO2 to ensure successful deterrence. This article is protected by copyright. All rights reserved.
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Carbon dioxide (CO 2 ) in water has been explored for use as an invasive species deterrent system. To date, studies have not determined CO 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 CO 2 . A choice experiment by which CO 2 was injected into channels of an annular flowing water flume was completed. In trials when CO 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 CO 2 . The study demonstrates that bighead carp in flowing water enriched with CO 2 move away, a finding consistent with static water experiments.
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Carbon dioxide (CO2) in fresh-water environments is poorly understood, yet in marine environments CO2 can affect fish behaviour, including predator–prey relationships. To examine changes in predator success in elevated CO2, we experimented with predatory Micropterus salmoides and Pimephales promelas prey. We used a two-factor fully crossed experimental design; one factor was 4-day (acclimation) CO2 concentration and the second factor CO2 concentration during 20-min predation experiments. Both factors had three treatment levels, including ambient partial pressure of CO2 (pCO2; 0–1000 μatm), low pCO2 (4000–5000 μatm) and high pCO2 (8000–10 000 μatm). Micropterus salmoides was exposed to both factors, whereas P. promelas was not exposed to the acclimation factor. In total, 83 of the 96 P. promelas were consumed (n = 96 trials) and we saw no discernible effect of CO2 on predator success or time to predation. Failed strikes and time between failed strikes were too infrequent to model. Compared with marine systems, our findings are unique in that we not only saw no changes in prey capture success with increasing CO2, but we also used CO2 treatments that were substantially higher than those in past experiments. Our work demonstrated a pronounced resiliency of freshwater predators to elevated CO2 exposure, and a starting point for future work in this area.
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The objectives of this research were (1) to experimentally quantify the dissolved carbon dioxide (CO2) production within a biofilter (2) to use stoichiometry to estimate the CO2 production that would be expected across the biofilter due to nitrification and heterotrophic oxygen (O2) demand (3) to compare the relative amounts of CO2 produced by the biofilter bacteria to the CO2 produced by the fish that are cultured in the recirculating system, and (4) to discuss implications for recirculating system design that must be considered when it is recognized that a large fraction of the CO2 produced in a recirculating system is produced by the biofilter.
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Several largemouth bass Micropterus salmoides tournaments in Ontario were visited in the summers of 1999 and 2000 to examine the physiological changes that occur in largemouth bass as a result of tournament procedures. Physiological variables were compared among tournament-caught largemouth bass, resting laboratory controls, and angled controls. The plasma cortisol and glucose concentrations and plasma osmolarity in tournament-caught largemouth bass sampled within 5 min following the weigh-in were significantly greater than those in both control groups. Tournament-caught fish also exhibited ionic disturbances that involved increases in plasma sodium and potassium concentrations, but there were no significant changes in the levels of plasma chloride. Large changes in the metabolic status of largemouth bass sampled following the weigh-in included major reductions in the muscle energy stores phosphocreatine, adenosine triphosphate, and glycogen and large increases in muscle and plasma lactate concentrations. In contrast, no significant changes occurred in the mRNA levels of heat-shock protein 70 in several tissues or in plasma creatine phosphokinase activity. Taken together, these results indicate that live-release angling tournaments cause a significant physiological disturbance in largemouth bass, but there is no evidence that these events normally result in serious cell damage.
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Species invasions pose a serious threat to biodiversity and native ecosystems(1,2); however, predicting and quantifying the impacts of invasive species has proven problematic(3-6). Here we use stable isotope ratios to document the food-web consequences of the invasion of two non-native predators, smallmouth bass and rack bass, into Canadian lakes. Invaded lakes had lower littoral prey-fish diversity and abundance than uninvaded reference lakes. Consistent with this difference, lake trout from invaded lakes had more negative delta(13)C values (-29.2 parts per thousand versus -27.4 parts per thousand) and reduced trophic positions (3.3 versus 3.9) than those from reference lakes, indicating differences in food-web structure, Furthermore, a comparison of the pre- and post-invasion food webs of two recently invaded lakes showed that invasion was followed by substantial declines in littoral prey-fish abundance and the trophic position of lake trout, reflecting a shift in the diet of lake trout towards zooplankton and reduced dependence on littoral fish. This study demonstrates the use of stable isotope techniques to detect changes in food-web structure following perturbations; in this instance, bass-induced food-web shifts may have severe consequences for native species and ecosystems.
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Convenient, economical, and reduced labor fish harvest and transfer systems are required to realize operating cost savings that can be achieved with the use of much larger and deeper circular culture tanks. To achieve these goals, we developed a new technology for transferring fish based on their avoidance behavior to elevated concentrations of dissolved carbon dioxide (CO2). We observed this behavioral response during controlled, replicated experiments that showed dissolved CO2 concentrations of 60–120 mg/L induced rainbow trout (Oncorhynchus mykiss) to swim out of their 11 m3 “growout” tank, through a transfer pipe carrying a flow with ≤23 mg/L dissolved CO2, into a second 11 m3 “harvest” tank. The research was conducted using separate groups of rainbow trout held at commercially relevant densities (40–60 kg/m3). The average weight of fish ranged from 0.15 to 1.3 kg during the various trials. In all trials that used a constant flow of low CO2 water (≤23 mg/L) entering the growout tank from the harvest tank, approximately 80–90% of the fish swam from the growout tank, through the transfer pipe, and into the harvest tank after the CO2 concentration in the growout tank had exceeded 60 mg/L. The fish that remained in the growout tank stayed within the area of relatively low CO2 water at the entrance of the transfer pipe. However, the rate of fish transfer from the growout tank to the harvest tank was more than doubled when the diameter of the transfer pipe was increased from 203 to 406 mm. To consistently achieve fish transfer efficiencies of 99%, water flow rate through the fish transfer pipe had to be reduced to 10–20% of the original flow just before the conclusion of each trial. Reducing the flow of relatively low CO2 water near the end of each fish transfer event, restricted the zone of relatively low CO2 water about the entrance of the fish transfer pipe, and provided the stimulus for all but a few remaining fish to swim out of the growout tank. Results indicate that the CO2 avoidance technique can provide a convenient, efficient, more economical, and reduced labor approach for fish transfer, especially in applications using large and well mixed circular culture tanks.
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Social interactions in small groups of juvenile rainbow trout (Oncorhynchus mykiss) lead to the formation of dominance hierarchies. Dominant fish hold better positions in the environment, gain a larger share of the available food and exhibit aggression towards fish lower in the hierarchy. By contrast, subordinate fish exhibit behavioural inhibition, including reduced activity and feeding. The behavioural characteristics associated with social status are likely the result of changes in brain monoamines resulting from social interactions. Whereas substantial physiological benefits, including higher growth rates and condition factor, are experienced by dominant trout, low social status appears to be a chronic stress, as indicated by sustained elevation of circulating cortisol concentrations in subordinate fish. High cortisol levels, in turn, may be responsible for many of the deleterious physiological consequences of low social status, including lower growth rates and condition factor, immunosuppression and increased mortality. Circulating cortisol levels may also be a factor in determining the outcome of social interactions in pairs of rainbow trout, and hence in determining social status. Rainbow trout treated with cortisol were significantly more likely to become subordinate in paired encounters with smaller untreated conspecifics.