Article

Potential for carbon dioxide to act as a non-physical barrier for invasive sea lamprey movement

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Abstract

Invasive sea lampreys have had substantial negative ecological and economic impacts on the Laurentian Great Lakes region. Control efforts, such as lampricide application and barriers, have resulted in a reduction in number of sea lampreys in the Great Lakes. Due to environmental and non-target impacts of existing control mechanisms, coupled with the fact that no non-physical barrier is completely effective at stopping fish movement, there is a critical need to develop novel control technologies to assist with the control and suppression of sea lamprey populations. Recent work has indicated that carbon dioxide gas (CO2) applied to water will influence the movement and behavior of fishes, providing the potential for CO2 to act as a non-physical barrier that can exclude fish from a target area. To date, the effectiveness of CO2 at influencing the movement and behavior of sea lampreys has not been explored. The current study showed that CO2 applied to water will result in behavioral agitation for both adult and transformer sea lampreys, and will eventually result in equilibrium loss. More importantly, both adult and transformer sea lampreys will ‘choose’ to avoid water with CO2 concentrations of 85 and 160 mg/L (respectively). Together, results from this study suggest that CO2 applied to water has the potential to act as a non-physical barrier to deter the movement of free-swimming lamprey in the wild. Carbon dioxide gas can be integrated with existing control technologies to act as a novel barrier technology and augment existing control strategies for sea lampreys.

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... Carbon dioxide (CO 2 ) is a non-physical barrier system that has recently been considered for control of adult and transformer sea lamprey movement. When applied to water, a portion of carbon dioxide will remain in solution while the rest hydrates to form carbonic acid which can dissociate, resulting in a reduction of water pH (Dennis et al., 2016). Dennis et al. (2016) found that both sea lamprey adults and transformers displayed agitation (i.e. ...
... When applied to water, a portion of carbon dioxide will remain in solution while the rest hydrates to form carbonic acid which can dissociate, resulting in a reduction of water pH (Dennis et al., 2016). Dennis et al. (2016) found that both sea lamprey adults and transformers displayed agitation (i.e. erratic swimming, elevated activity, and twitching) when concentrations of CO 2 exceeded 40 mg/L and sea lamprey experienced loss of equilibrium at concentrations above 120 mg/L. ...
... Minimal infrastructure Species-specific Many uncertainties Further refinements needed Siefkes, 2017Dennis et al., 2016Klingler and Mullett, 2001Miehls et al., 2017bStamplecoskie et al., 2012Fredricks et al. 1996Purvis et al., 1985 and continued reliance in the sea lamprey control program. While fixed-crest barriers are the current standard for sea lamprey control barriers, mounting societal desire for increased connectivity and potential changes to hydrology across the basin will require evolving and alternative designs to achieve the same level of control. ...
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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.
... 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). ...
... In addition, we expected a compounding effect of successive exposures to CO 2 to occur that would result in the same behavioral responses at potentially lower pCO 2 . Previous work has shown that an individual's responses to a repetitive stimulus may be compounded or attenuated (Reinert et al. 2002), and more specifically that fish avoid areas of elevated CO 2 even after multiple exposures (Kates et al. 2012;Dennis et al. 2016b). One proposed deployment strategy involves the addition of CO 2 into a shipping lock (United States Army Corps of Engineers 2014), as locks can serve as a chokepoint in a waterway to reduce the volume of water to be treated with CO 2 . ...
... Alternatively, fish could also be learning that the stimulus in the experiment was not associated with any adverse outcomes. Tierney (2016) showed that CO 2 is a compound that normally elicits unconditioned avoidance in fish, and several studies have shown that fish will avoid elevated CO 2 following multiple exposures (Kates et al. 2012;Dennis et al. 2016b), so the lack of response after successive exposures could be a result of some degree of non-associative learning (Best et al. 2008). In the past, CO 2 has been used as a fish anesthetic (Gilderhus and Marking 1987), thus prolonged exposure could result in a decrease in activity. ...
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Article
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). ...
... 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. ...
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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.
... 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). ...
... 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). Similar responses were observed in pond studies where fish temporarily moved away from the CO 2 source until the pond was completely mixed (Donaldson et al., 2016) and passages through the injection site were reduced (Cupp et al., 2017a). ...
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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.
... Improving the survival of juveniles of vulnerable lamprey species could include preventing them from being impinged at water intake screens (Moser et al., 2015) or entrained by surface water diversions (Goodman et al., 2017;Liedke et al., 2019). Intentionally entraining juvenile sea lamprey in the Great Lakes could provide the ability to control or assess juveniles prior to the onset of feeding (Dennis III et al., 2016;Johnson and Miehls, 2013;Miehls et al., 2017). For example, Goodman et al. (2017) estimate the San Joaquin-Sacramento River Estuary water diversion, which bears an intake screen designed for salmonids, entrains 95% of juvenile Pacific and western river lamprey. ...
... However, evidence of the utility of light to guide juvenile or adult sea lamprey in the Great Lakes has been weak and often contrary to predictions (e.g., attraction to light; Johnson et al., 2019;Miehls et al., 2017;Stamplecoskie et al., 2012). Similar non-physical stimuli, applied singly or in combination, are being investigated for their ability to manage sub-adult sea lamprey, including aversion to CO 2 (Dennis III et al., 2016) and sound (Mickle et al., 2019;Miehls et al., 2017). ...
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Article
Abstract Lampreys (Petromyzontiformes) are a key component of freshwater ecosystems throughout temperate parts of the world. Of the ~ 44 described species of lamprey, the sea lamprey (Petromyzon marinus) is certainly the most commonly recognized. This species has expanded its range from the Atlantic Ocean basin where it is of conservation concern in North America and Europe, into the Laurentian Great Lakes where it is subject to a large-scale international control program. Many other species of lamprey are imperiled and require management intervention to ensure their persistence. These management efforts range from routine assessment and monitoring to active or proposed restoration plans where they have been extirpated. Regardless of whether the goal is to control or conserve a given lamprey population, an understanding of their basic biology is paramount when generating and executing management plans. Here, we take a broad look across core aspects of biology (survival, foraging, and reproduction) that encompass challenges and opportunities in regards to future science-based management of lampreys. We attempt to synergize basic and applied research to highlight where these findings are most applicable to solving management problems, and reveal knowledge gaps. We conclude by suggesting future research avenues and questions aimed to stimulate progress in both basic and applied lamprey research.
... 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). ...
... 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.
... 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). ...
... Results from our study have implications not only for the relationship between physiology and behavior in fishes, but also for managers working to develop non-physical CO 2 deterrent systems. CO 2 as a management tool is primarily proposed to block the movement of invasive species such as bigheaded carp (Cupp et al. 2017a, b;Donaldson et al. 2016), sea lamprey (Dennis et al. 2016), and round goby (Cupp et al. 2017b). Previous studies have demonstrated that teleost fish of different species do not vary significantly in their avoidance of CO 2 (Kates et al. 2012;Donaldson et al. 2016), allowing largemouth bass and bluegill to serve as suitable proxies for invasive fishes in a controlled laboratory environment. ...
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Article
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.
... 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. ...
... Although increased acidity can alter fish behavior due to its detrimental effects on blood chemistry and acid-base regulation (Perry and Gilmour 2006;Ern and Esbaugh 2016), research suggests that gill chemoreceptors allow fish to sense and differentiate between H + and CO 2 (Jones et al. 1985;Ishimatsu et al. 2005;Perry and Abdallah 2012). A few studies have demonstrated that fish specifically avoid areas of elevated CO 2 when given access to ambient fresh water (Clingerman et al. 2007;Dennis et al. 2016;Cupp et al. 2017a). Furthermore, others have hypothesized that a CO 2 barrier could reduce invasive fish passage by creating hypoxic or anoxic conditions through displacement of dissolved oxygen . ...
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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.
... Indeed, hypercapnia has been investigated for use as a barrier against for the movement of invasive fish species. Silver and bighead carp demonstrate avoidance behaviour when exposed to 4 and 24 kPa PCO 2 (Cupp et al., 2017;Hasler et al., 2019), while avoidance behaviour occurred when juvenile sea lamprey were exposed to ~21 kPa PCO 2 (Dennis et al., 2016). Thus, CD max appears only to indicate the absolute highest CO 2 tension they can physiologically tolerate, as fishes will likely choose to avoid hypercapnia to minimize the risk of experiencing LOE or other behavioral or physiological changes. ...
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.
... 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 ). ...
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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.
... 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.
... In addition, responses of fish to hypercarbia in aquaculture, in particular recirculating aquaculture systems (Fivelstad, 2013;Good et al., 2018;Hafs et al., 2012;Khan et al., 2018;Steinberg et al., 2017) and intensive fish culture in ponds (Crocker and Cech Jr, 1996;Damsgaard et al., 2015;Gam et al., 2018), is of increased interest. There is also interest in using CO 2 as a non-physical barrier to prevent fish migration (Dennis et al., 2016;Noatch and Suski, 2012;Schneider et al., 2018), and the potential impacts of CO 2 sequestration on aquatic vertebrates are of concern (Hawkins, 2004;Lackner, 2003;Seibel and Walsh, 2001). ...
Article
Aquatic CO2 tensions may exceed 30-60 Torr (ca. 30,000-79,000 μatm, respectively; hypercarbia) in some environments inducing severe acid-base challenges in fish. Typically, during exposure to hypercarbia blood pH (pHe) is initially reduced and then compensated in association with an increase in plasma HCO3- in exchange for Cl-. Typically, intracellular pH (pHi) is reduced and recovery is to some degree coupled to pHe recovery (coupled pH regulation). However, during acute hypercarbia, pHe recovery has been proposed to be limited by an "apparent upper bicarbonate threshold", restricting complete pHe recovery to below 15 Torr PCO2. At PCO2 values beyond that which fish can compensate pHe, some fish are able to fully protect pHi despite large sustained reductions in pHe (preferential pHi regulation) and can tolerate PCO2 > 45 Torr. This review discusses pHe and pHi regulation during exposure to hypercarbia starting with modeling the capacity and theoretical limit to pHe compensation in 19 studies. Next, we discuss how fish compensate severe acute hypercarbia exposures beyond the putative limit of pHe compensation using preferential pHi regulation which has recently been observed to be common among fish subjected to severe hypercarbia. Finally, we consider the evolution of pH regulatory strategies in vertebrates, including how the presence of preferential pHi regulation in embryonic reptiles may indicate that it is an embryonic trait that is either lost or retained in adult vertebrates and may have served as an exaptation for key evolutionary transitions during vertebrate evolution.
... As such, CO 2 is being considered as a barrier to deter the movements of invasive bigheaded carp in Illinois, with flowing water as a potential application site (United States Army Corps of Engineers 2014). Target pCO 2 for the barrier based on previous findings has been estimated to be around 30,000-50,000 μatm Dennis et al. 2016b;Donaldson et al. 2016). Deployment strategies will likely involve injecting CO 2 into a lock or creating a Bwallô f CO 2 at a chokepoint such as a culvert or a lake inlet, with elevated pCO 2 presumably dissipating as water flows downstream. ...
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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.
... Applying CO 2 to achieve these behavioral outcomes could reduce or prevent the upstream movements of nuisance fishes through navigational structures. Behavioral responses and toxicity of elevated CO 2 to invasive fishes have already been successfully documented under controlled settings with bigheaded carps, round goby (Neogobius melanostomus), and sea lamprey (Petromyzon marinus) [4][5][6][7][8], but transitioning this method into permanent field installations for AIS management requires further investigation of injection system designs and fluid mechanics. ...
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Article
Aquatic invasive species (AIS) have spread throughout the United States via major rivers and tributaries. Locks and dams positioned along affected waterways, specifically lock chambers, are being evaluated as potential management sites to prevent further expansion into new areas. Recent research has shown that infusion of chemicals (e.g., carbon dioxide) into water can block or kill several invasive organisms and could be a viable option at navigational structures such as lock chambers because chemical infusion would not interfere with vessel passage or lock operation. Chemical treatments near lock structures will require large-scale fluid-mechanic systems and significant energy. Mixing must extend to all stagnation regions within a lock structure to prevent the passage of an invasive fish. This work describes the performance of both wall- and floor-based CO2-infused-water to water injection manifolds targeted for lock structures in terms of mixing time, mixing homogeneity, injection efficiency and operational power requirements. Both systems have strengths and weaknesses so selection recommendations are given for applications such as open systems and closed systems.
... 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. ...
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.
... During downstream migration, juvenile Pacific Lamprey can become impinged on intake screens or entrained in irrigation canals; they may experience other physical injury resulting in direct mortality ( Moser et al. 2015). Prior research has considered aversive stimuli to direct juvenile lampreys, including electrical guidance ( Applegate et al. 1952;Johnson and Miehls 2014) and other nonphysical stimuli such as carbon dioxide barriers ( Dennis et al. 2016). These technologies often require costly infrastructure, making whole-channel implementation difficult and expensive. ...
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Instream barriers affect anadromous lampreys worldwide by preventing access to spawning habitat, resulting in the decline of several species. Because lampreys rely heavily on olfactory cues to choose movement paths during upstream migration in rivers, the manipulation of these cues may be used to guide individuals into the vicinity of fish passage devices and thereby mitigate the impacts of barriers during migration. However, because experimentation with imperiled species presents significant legal and ethical challenges, use of a surrogate species that exhibits similar responses may prove very useful. Our laboratory study established that (1) the odor derived from dead Pacific Lamprey Entosphenus tridentatus elicits an avoidance response from invasive Sea Lamprey Petromyzon marinus from the Laurentian Great Lakes, and (2) the magnitude of this response does not differ from the conspecific alarm cue present in Sea Lamprey. By presenting the odor on the side of a river channel opposite a lamprey fish passage device, migrating lampreys of conservation concern may be guided to fishways, if the behavioral response to the cue has evolved in these taxa. Due to their availability and well-studied chemical communication system, Sea Lamprey may prove to be a useful surrogate for identifying and producing chemosensory cues for use in guiding Pacific Lampreys towards fish passage devices and away from intakes and screens. Received December 10, 2015; accepted May 6, 2016
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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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Control of the invasive Sea Lamprey (Petromyzon marinus) is critical for management of commercial and recreational fisheries in the Laurentian Great Lakes. Blocking Sea Lamprey from spawning habitat with physical barriers is a major component of the control program. However, the resulting interruption of natural stream flow and blockage of nontarget species present substantial challenges. Development of an effective nonphysical barrier would aid the control of Sea Lamprey by eliminating access to Sea Lamprey spawning locations while maintaining natural stream flow. We tested the effect of a nonphysical barrier consisting of strobe lights, low-frequency sound, and a bubble screen on the movement of Sea Lamprey in an experimental raceway designed as a two-choice maze with a single main channel fed by two identical inflow channels (one control and one blocked). Sea Lamprey were more likely to move upstream during trials when the strobe light and low-frequency sound were active compared with control trials and trials with the bubble screen alone. For those Sea Lamprey that did move upstream to the confluence of inflow channels, no combination of stimuli or any individual stimulus significantly influenced the likelihood of Sea Lamprey entering the blocked inflow channel, the control channel, or returning downstream. Received 04 Oct 2016 accepted 15 Mar 2017 revised 10 Mar 2017
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The capacity of organisms to sense changes in the levels of internal and external gases and to respond accordingly is central to a range of physiologic and pathophysiologic processes. Carbon dioxide, a primary product of oxidative metabolism is one such gas that can be sensed by both prokaryotic and eukaryotic cells and in response to altered levels, elicit the activation of multiple adaptive pathways. The outcomes of activating CO2-sensitive pathways in various species include increased virulence of fungal and bacterial pathogens, prey-seeking behavior in insects as well as taste perception, lung function, and the control of immunity in mammals. In this review, we discuss what is known about the mechanisms underpinning CO2 sensing across a range of species and consider the implications of this for physiology, disease progression, and the possibility of developing new therapeutics for inflammatory and infectious disease.
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The Friedman test (or sign test when k = 2) depends entirely on within-block rankings. In a recent paper, Quade (1979) attempted to provide a test with more power than the Friedman test by considering a k-sample extension of the Wilcoxon signed ranks test. This is done by taking advantage of the between-block information. A third way to approach the problem and still retain both the within- and between-block information is first to transform all the observations to ranks from 1 to bk (b blocks and k treatments) and then to apply the parametric F test to the ranks. This approach is shown to be asymptotically distribution-free under suitable conditions. Computer simulation results indicate that this procedure is both robust and powerful for small sample sizes.
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Many of the more useful and powerful nonparametric procedures may be presented in a unified manner by treating them as rank transformation procedures. Rank transformation procedures are ones in which the usual parametric procedure is applied to the ranks of the data instead of to the data themselves. This technique should be viewed as a useful tool for developing nonparametric procedures to solve new problems.
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Summary The role of central chemosensitivity in the control of ventilation in fishes was investigated directly by perfusing a mock extradural fluid (EDF) through the cranial space in the medullary region of conscious air-breathing fish, Amia calva. Perfusions with Sudan Black dye showed that the mock EDF communicated with the cerebrospinal fluid (CSF) and entered the cerebral ventricles. Altering the Po2, Pco2 and/or pH of the mock EDF had no effect on gill- or air-breathing rates, heart rate or blood pressure during exposure to normoxic water. Aquatic hypoxia, however, stimulated gill ventilation and elevated blood pressure, but did not affect heart rate; altering the gas tensions and/or pH of mock EDF still had no effect on recorded variables. Sodium cyanide (NaCN) added to the mock EDF caused struggling at concentrations above 500 ^gmP 1, but did not uniformly stimulate ventilation. These results suggest that central chemoreceptors, which mediate cardiovascular or ventilatory reflexes, are absent in Amia.
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After making a case for the prevalence of nonnormality, this paper attempts to introduce some distribution-free and robust techniques to ecologists and to offer a critical appraisal of the potential advantages and drawbacks of these methods. The techniques presented fall into two distinct categories, methods based on ranks and ''computer-intensive'' techniques. Distribution-free rank tests have features that can be recommended. They free the practitioner from concern about the underlying distribution and are very robust to outliers. If the distribution underlying the observations is other than normal, rank tests tend to be more efficient than their parametric counterparts. The absence, in computing packages, of rank procedures for complex designs may, however, severely limit their use for ecological data. An entire body of novel distribution-free methods has been developed in parallel with the increasing capacities of today's computers to process large quantities of data. These techniques either reshuffle or resample a data set (i.e., sample with replacement) in order to perform their analyses. The former we shall refer to as ''permutation'' or ''randomization'' methods and the latter as ''bootstrap'' techniques. These computer-intensive methods provide new alternatives for the problem of a small and/or unbalanced data set, and they may be the solution for parameter estimation when the sampling distribution cannot be derived analytically. Caution must be exercised in the interpretation of these estimates because confidence limits may be too small.
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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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Ectothermic vertebrates respond to the temperature of their habitat in a manner that is remarkably similar to their response to more traditional ecological resources such as food. We review the response to temperature primarily from literature on fishes in terms of ecological concepts related to niche theory and competition. The width of the fundamental thermal niche is about 4°C when measured by a mean plus and minus one standard deviation of the distribution of temperature occupied in a laboratory gradient. Fish of temperate freshwater appear to fall into three thermal guilds along the temperature resource axis —cold, cool, and warm water fishes. Realized thermal niches are similar in central tendency to fundamental niches, but niche width appears to be more narrow for the realized niche in limited sample data. The success of interference competition for space with preferred temperature is tied to social dominance in a manner analogous to food competition. Thermal niche shifts in the face of interspecific competition for preferred temperature appear supported by one laboratory study. Exploitation competition in respect to temperature seems nebulous. If animals successfully compete for their thermal niche, growth and perhaps other measures of fitness are maximized. Cost&sol;benefit models for thermal resources and food resources lead to similar predictions about resource use. We suggest that viewing temperature and other niche axes in the way ecologists have viewed food resources would be useful.
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The persistence of most coastal marine species depends on larvae finding suitable adult habitat at the end of an offshore dispersive stage that can last weeks or months. We tested the effects that ocean acidification from elevated levels of atmospheric carbon dioxide (CO(2)) could have on the ability of larvae to detect olfactory cues from adult habitats. Larval clownfish reared in control seawater (pH 8.15) discriminated between a range of cues that could help them locate reef habitat and suitable settlement sites. This discriminatory ability was disrupted when larvae were reared in conditions simulating CO(2)-induced ocean acidification. Larvae became strongly attracted to olfactory stimuli they normally avoided when reared at levels of ocean pH that could occur ca. 2100 (pH 7.8) and they no longer responded to any olfactory cues when reared at pH levels (pH 7.6) that might be attained later next century on a business-as-usual carbon-dioxide emissions trajectory. If acidification continues unabated, the impairment of sensory ability will reduce population sustainability of many marine species, with potentially profound consequences for marine diversity.
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Experiments were performed to test the hypothesis that the marked ventilatory and cardiovascular responses to hypercarbia in rainbow trout Oncorhynchus mykiss arise from specific stimulation of chemoreceptors localised to the first gill arch. This was accomplished by measuring cardiorespiratory variables during acute hypercarbia (20 min at P(CO(2))=8 mmHg; 1 mmHg=0.133 kPa) in fish subjected to selective bilateral extirpation of the first gill arch. The cardiovascular responses to hypercarbia in the intact fish included a significant bradycardia (from 75.0+/-1.6 to 69.0+/-2.0 beats min(-1); means +/- S.E.M.; N=16), an increase in dorsal aortic blood pressure (from 30.8+/-1.5 to 41.9+/-2.5 mmHg; N=16) and a rise in systemic vascular resistance (from 1.1+/-0.1 to 1.4+/-0.1 mmHg ml(-1) kg(-1) min(-1); N=16). Removal of the first gill arch or pre-treatment with the muscarinic receptor antagonist atropine prevented the hypercarbic bradycardia without affecting the pressure or resistance responses. Correlation analysis, however, revealed shallow but significant inverse relationships between water P(CO(2)) and cardiac frequency in both atropinised (r(2)=0.75) and gill-extirpated (r(2)=0.90) fish, suggesting a direct mild effect of CO(2) on cardiac function. The ventilatory response to hypercarbia in the intact fish consisted of an increase in ventilation amplitude (from 0.62+/-0.06 to 1.0+/-0.13 cm; N=16) with no change in breathing frequency. Removal of the first gill arch lowered resting breathing frequency and prevented the statistically significant elevation of breathing amplitude. Gill extirpation, however, did not totally abolish the positive correlation between water P(CO(2)) and ventilation amplitude (r(2)=0.84), suggesting the presence of additional (although less important) chemoreceptive sites that are not confined to the first gill arch. Plasma catecholamine levels were elevated during hypercarbia, and this response was unaffected by prior gill extirpation. To assess whether the CO(2) chemoreceptors of the first gill arch were sensing water and/or blood P(CO(2)), bolus injections of CO(2)-enriched water or saline were made into the buccal cavity or caudal vein, respectively. Injections of CO(2)-enriched water to preferentially stimulate external receptors evoked catecholamine release and cardiorespiratory responses that closely resembled the responses to hypercarbia. As in hypercarbia, extirpation of the first gill arch prevented the bradycardia and the increase in ventilation amplitude associated with externally injected CO(2)-enriched water. Except for a slight decrease in cardiac frequency (from 73.0+/-2.8 to 70.3+/-3.5 beats min(-1); N=11), injection of CO(2)-enriched saline to preferentially stimulate internal chemoreceptors did not affect any measured variable. Taken together, these data indicate that, in rainbow trout, the bradycardia and hyperventilation associated with hypercarbia are triggered largely by external CO(2) chemoreceptors confined to the first gill arch.
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Bigheaded carps are non-native invasive fishes that have quickly become the most abundant fishes in many portions of the Midwestern United States. While the spread of bigheaded carps into the Great Lakes is currently impeded by three electrified barriers, these fish have the potential to negatively impact the Great Lakes ecosystem if this barrier is breached, and these barriers may be particularly vulnerable to the passage of small fishes. As such, novel barrier technologies would provide an additional mechanism to prevent bigheaded carps from invading the Great Lakes, and provide much needed redundancy to the current electric barrier. The current study used a combination of molecular and behavioral experiments to determine the effectiveness of carbon dioxide as a chemical deterrent for larval and juvenile fishes, with an emphasis on bigheaded carps. Juvenile silver carp (Hypophthalmichthys molitrix), bighead carp (H. nobilis), bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) showed avoidance of elevated CO2 environments at approximately 200 mg/L. Additionally, exposure to 120 mg/L CO2 resulted in the induction of hsp70 mRNA in 8 days old silver carp fry, while gill c-fos transcripts increased following hypercarbia exposure in all juvenile species examined. Together, our results show that CO2 has potential to deter the movement of larval and juvenile fishes.
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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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Hypercarbia, or elevated carbon dioxide, is an environmental challenge that can have detrimental effects on the physiology and performance of aquatic organisms. With aquatic hypercarbia predicted to become more prevalent in the future due to global climate change, it is important to quantify how hypercarbia impacts aquatic organisms, especially fish. The impact of hypercarbia on the behavior and physiology of fishes has been well studied, but relatively few studies have examined the molecular processes that underlie resulting behavioral and physiological changes. In an effort to define the molecular response of fishes to acute hypercarbia exposure, bluegill (Lepomis macrochirus) and silver carp (Hypophthalmichthys molitrix) were exposed to either 30mgL(-1) CO2 (pCO2≈15700 μatm) or ambient (10mgL(-1) CO2; pCO2≈920 μatm) conditions for 1h and the expression of a variety of genes, across three tissues, were compared. Exposure to 30mgL(-1) CO2 in bluegill and silver carp resulted in an increase in c-Fos, HIF1-α, and GR-2 transcripts, while silver carp alone showed increases in Hsp70 and Hsc70-2 mRNA. This study demonstrates that acute hypercarbia exposure impacts gene expression in a species and tissue specific manner, which can be useful in identifying potential mechanisms for hypercarbia tolerance between species, and pinpoint specific tissues that are sensitive to hypercarbia exposure.
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A number of methods for examining the residuals remaining after a conventional analysis of variance or least-squares fitting have been explored during the past few years. These give information on various questions of interest, and in particular, aid in assessing the validity or appropriateness of the conventional analysis. The purpose of this paper is to make a variety of these techniques more easily available, so that they can be tried out more widely.Techniques of analysis, some graphical, some wholly numerical, and others mixed, are discussed in terms of the residuals that result from fitting row and column means to entries in a two-way array (or in several two-way arrays). Extensions to more complex situations, and some of the uses of the results of examination, are indicated.
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Sea lamprey (Petromyzon marinus) entered the upper three Great Lakes in the late 1930s and began making sharp inroads into the fish stocks by the mid-1940s in lakes Huron and Michigan and the mid-1950s in Lake Superior. The first serious attempts to control the parasite began in 1950 with the installation of mechanical barriers along the United States shore of Lake Huron to block spawning runs. Electrical barriers, developed in 1952, were installed in 132 tributaries of the Great Lakes by 1960, but control measures did not become effective until after 1958, when a selective toxicant — the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) — was used to destroy larval lampreys in streams. In the 21 years, 1958–78, 1223 treatments of tributaries of the upper three lakes with TFM were completed in 334 streams — 91 in Canada and 243 in the United States. Evidence of the success of the control program was soon obvious: first by reduced sea lamprey spawning runs as measured by the numbers of adults taken at elect...
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Some physiological aspects of five fish anaesthetics in rainbow trout were investigated. The effects of benzocaine, 2-phenoxyethanol, MS-222 (Sandoz), metomidate, and carbon dioxide gas (CO2) on acid–base regulation, hematocrit, blood gases, and cortisol and adrenaline concentrations were determined in resting rainbow trout fitted with chronic catheters in the dorsal aorta. A severe hypoxia developed with the cessation of breathing in deep anaesthesia. This was accompanied by a rise in blood and adrenaline concentration, and a fall in blood pH. Blood bicarbonate concentrations remained unchanged and cortisol concentrations declined with time. There was a transient increase in hematocrit coinciding with the increase in adrenaline concentrations.
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This paper provides a brief history of sea lamprey (Petromyzon marinus) control in the Great Lakes and introduces the second Sea Lamprey International Symposium (SLIS II). SLIS II was held during August 2000 to synthesize advances in sea lamprey management during the two decades since the first Sea Lamprey International Symposium (SLIS I) in 1979. SLIS I was convened by the Great Lakes Fishery Commission (the commission) to reflect on the effects of the first 20 years of sea lamprey control. Recommendations from SLIS I guided advances in the sea lamprey control program that are reported in this volume, including: improvements in chemical control methods; refinements in monitoring of the effectiveness of alternative methods; evaluations of changes in stream production; the search for natural controls; improvements in the understanding of sea lamprey population regulation; better estimation of alternative sources of sea lamprey; and improved understanding of the damage caused by sea lampreys. The most significant development emerging from SLIS I was the policy of Integrated Management of Sea Lamprey (IMSL) that was ultimately adopted by the commission in its Strategic Vision. IMSL was organized around the concepts of Integrated Pest Management (IPM) including: defining targets for control that optimize benefits; application of alternative techniques; and use of quantitative methods and systems approaches. Decision support tools have been developed to aid tactical control planning and to estimate strategic targets for sea lamprey management. The science reported in this volume points the way toward further improvements in the effectiveness and efficiency of sea lamprey management in the Great Lakes.
Article
Atlantic salmon (Salmo salar) presmolts, smolts, and postsmolts compensate for a respiratory acidosis associated with 96 h of exposure to hyperoxia (100% O2; hO2), hypercapnia (2% CO2 and 98% air; hCO2), and combined hO2/hCO2 in freshwater (FW) by increasing strong ion difference, predominantly through a reduction in plasma [Cl-] (presumably via branchial Cl-/HCO3- exchange). In smolts, compensation during hO2 or hCO2 occurred within 24 h, whereas that in combined hO2/hCO2 was much slower, resulting in 33% mortality by 96 h. FW hO2 and combined hO2/hCO2 appeared to impair gill function, likely through oxidative cell damage. This resulted in reduced hypoosmoregulatory ability following subsequent transfer to seawater (SW), as indicated by changes in plasma ion levels, osmolality, and muscle water content, resulting in considerable mortalities. Interestingly, FW hCO2 appeared to enhance hypoosmoregulatory ability during subsequent SW transfer. Smolts are often transported from FW to a subsequent SW release site, and these data indicate that care should be taken to minimize the degree of hyperoxia experienced by the smolts. Hypercapnia, which results from metabolic CO2 production and inadequate water aeration, does not impair SW transfer, provided it does not occur in conjunction with hyperoxia.
Article
Anthropogenic modifications to aquatic ecosystems have altered connecting pathways within, and in some cases, between watersheds. Human structures, such as hydroelectric facilities, often impede fish migrations and may inflict heavy mortality on fish that become impinged or entrained. Conversely, an increase in connectivity between two waterways (e.g., through the construction of shipping canals, increased boat traffic) often results in an elevated risk of invasive species introductions. Non-physical barriers, which obstruct fish from an undesirable location without influencing the waterway, are one management approach to protecting valuable fish stocks and deterring biological invasions. Because many methods of behavioral deterrence have been employed against fish, there is a need to summarize and compare existing and developing technologies. This review details the use and application of electrical, visual, acoustic, chemical, and hydrological deterrence techniques that may be used to prevent fish movements. Site requirements are discussed, and a critical assessment of benefits and limitations to each technique are given. Because no single method of fish deterrence is “one size fits all”, this review to non-physical fish barrier technology will benefit managers and researchers attempting to develop a best-fit strategy on a case-by-case basis.
Article
We estimated economic injury levels (EILs) and associated optimal control budgets for sea lamprey Petromyzon marinus for each of the Great Lakes using common assumptions and consistent methods. The lake-specific EILs are defined as equilibrium sea lamprey abundances below which incremental increases in control expenditures do not pay for themselves in terms of benefits (in the form of increased harvest of desired host species). We assume that sea lamprey control efforts result in an increase in the availability of adult hosts for fishery harvest, which provides economic value to society. We used a stochastic population model to simulate the sea lamprey life cycle as well as management actions (e.g., treatment of streams with lampricide) over a range of potential control budgets. Prior to running simulations, the model was calibrated for each Great Lake so that resulting forecasts were consistent with recent observed adult (spawning-phase) sea lamprey abundance levels given recent control budgets. Our calculated EILs suggest that sea lamprey abundances lower than those currently observed or those specified by interim damage targets are justifiable and may be obtainable with increases in control budgets (roughly 25% to 55% per lake). This conclusion is robust to a range of plausible assumptions about the economic benefits attributable to host fish.Received January 21, 2011; accepted April 9, 2012
Article
This paper provides a rigorous and directed research framework for fostering innovations in the design, implementation, and operation of barriers, traps, and fishways used to control the sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes. It was developed to support the Great Lakes Fishery Commission's milestone pledging to decrease reliance on chemical lampricides and achieve 50% of sea lamprey suppression through alternative control technologies, including barriers and traps. The paper first substantiates the need to develop a long-term research plan for barriers, traps, and fishways by summarizing (i) current management challenges, (ii) the barrier, trap, and fishway options being used to meet these challenges, and (iii) the key uncertainties in our knowledge regarding these options. The paper then proposes a long-term research strategy that envisions a transition from barriers designed to block the upstream spawning migrations of sea lamprey, to barrier and trap combinations that facilitate physical removal of sea lamprey and, in some cases, passage of non-target fishes, to barrier and trap designs that are specific to sea lamprey, transparent to non-target fishes, and safer for operators. Thirteen research needs are identified to support this strategy along with a general work plan on how they can be achieved. The research needs and work plan highlight the exceptional opportunity to develop the Great Lakes basin as a leading, international research center for fish migration and passage, and the development of environmentally friendly barriers.
Article
Legislation has been introduced this year in the U.S. Congress, but not yet enacted, that would direct the U.S. Army Corps of Engineers to complete a study of the options that would prevent the spread of aquatic nuisance species between the Great Lakes and Mississippi River Basins. Hydrologic separation is the only option which closes the aquatic connection between the two basins and does not require continuous operation and maintenance of various technologies that have some risk of failure. The one-time, capital cost to separate the two basins is widely acknowledged to be high, and the outstanding question is whether the costs are justified given the significant risk of future ecological damages and long-term economic losses. Interests opposing separation have mounted a public campaign that the news media have picked up to deny that hydrologic separation should be considered or that a problem even exists. The campaign rests on four assertions: (1) existing electric barriers in the Chicago canals are effective; (2) it is too late–the carps are already in the Great Lakes or soon will be; (3) Asian carps will not thrive in the Great Lakes due to inadequate food and spawning habitat; and (4) Asian carps are unlikely to cause serious harm. Our review of these assertions and the ecological and socio-economic threats to both basins supports our recommendation that the pending legislation be passed and that it include analysis of hydrologic separation of the two basins.
Chapter
Introduction: A Brief Historical PerspectiveImpacts of Invasions on Freshwater BiodiversityCascading Impacts on Food WebsComplex Interactions Among SpeciesPredictability of ImpactAre Freshwater Systems More Sensitive to the Impacts of Introduced Species?Conclusions and Future ProspectsAcknowledgementsReferences
Article
The physiological and anaesthetic effects of three different levels of air-saturated and buffered CO2 anaesthesia, Pwco2=31, 78, or 125 mmHg, were examined in cannulated rainbow trout Oncorhynchus mykiss . Complete anaesthesia (no opercular movements) was not achieved by these hypercapnic levels after 20 min of CO2 exposure. Although increasing Pwco2 reduced the induction times to the early stages of anaesthesia, it also resulted in increasing hyperventilatory, hypoxaemic, and acid-base disturbances. After a 10-min recovery period, while the respiratory acidosis component of the acid-base disturbance was corrected, there was a significant metabolic acidosis. Recovery time was longest in the high Pw co2 treatment where 33% of the fish died. Two additional groups (Pwco2=37 and 78 mmHg) were exposed to an acute stress prior to the anaesthetic treatment. Stress reduced the hypoventilatory effects of the low Pwco2 treatment, increased the recruitment of anaerobic metabolism, and prolonged recovery time. Although the increase in plasma catecholamines elicited by the stress was small relative to the response obtained with the anaesthetic, stress prior to CO2 anaesthesia impaired the efficiency of the treatment. Overall, our results suggest that Pwco2 levels above 37 mmHg and/or stress prior to the anaesthesia impair the efficiency of air-saturated and buffered CO2 anaesthesia by exacerbating the hypoxaemic effects of the hypercapnic treatment.
Article
This essay reviews the behavioral responses of fish to reduced levels of dissolved oxygen from the perspective of optimization theory as used in contemporary behavioral ecology. A consideration of oxygen as a resource suggests that net oxygen gain per unit of energy expenditure will be the most useful currency for ecological models of breathing. In the process of oxygen uptake, fish always expend energy on perfusion, usually on ventilation and often on locomotion. These costs, and the risk of predation, will vary with oxygen availability and the type of behavioral response shown. The principal categories of behavioral response to reduced external availability of dissolved oxygen are (1) changes in activity, (2) increased use of air breathing, (3) increased use of aquatic surface respiration, and (4) vertical or horizontal habitat changes. Fish should choose whichever combination of responses minimizes the costs of meeting their oxygen demands. A small number of studies provides qualitative support for this prediction.
Article
We collected actively migrating juvenile Pacific lamprey Lampetra tridentata [Richardson, J. 1836. Fauna Boreali-Americana; or the zoology of the northern parts of British America: containing descriptions of the objects of natural history collected on the late northern land expeditions, under the command of Sir John Franklin. R.N., Fauna Boreali-Americana, 327 pp.] from hydroelectric bypass facilities in the Columbia River and transferred them to the laboratory to study diel movement patterns and swimming ability. Volitional movement of lamprey was restricted mainly to night, with 94% of all swimming activity occurring during the 12h dark period. Burst speed of juvenile lamprey (mean length 136 ± 5mm SD) ranged from 56 to 94cms−1 with a mean of 71 ± 5 SD cms−1 or an average speed of 5.2s−1 body lengths (BL). Sustained swim speed for 5min test intervals ranged from 0 to 46cms−1 with a median of 23cms−1. Critical swimming speed was 36.0 ± 10.0 SDcms−1 and 2.4 ± 0.6 SD BL s−1. We found no significant relationship between fish length and critical swimming speed. These findings show that swimming performance of juvenile Pacific lamprey is low compared to anadromous teleosts. Their poor swimming ability provides a challenge when they encounter man-made structures and reservoirs during the freshwater migration interval downstream to the Pacific Ocean.
Article
Invading alien species in the United States cause major environmental damages and losses adding up to almost $120 billion per year. There are approximately 50,000 foreign species and the number is increasing. About 42% of the species on the Threatened or Endangered species lists are at risk primarily because of alien-invasive species.
Article
Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. Implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to “take a risk” with prevention.
1.1. Carp were cannulated in the dorsal aorta and the changes in arterial blood gas were examined during 30 min CO2 anesthesia under differing conditions and during the subsequent 60 min recovery period. The mean PaCO2, PaO2, and pHa of the carp (n = 50) before anesthesia were 3, 63, and 7.78 mmHg, respectively.2.2. All of the carp became anesthetized to Stage II (initial stage of anesthesia) or higher when treated with water containing high concentrations of CO2 (more than pCO2 = 125 mmHg), while only one carp out often reached Stage II at PwCO2 = 100 mmHg. The mean induction time of anesthesia (Stage II) was 23 (n = 1), 20, 12, and 8 min at PwCO2 = 100,125,175, and 250 mmHg, respectively. At Stage II, the mean PaCO2, PaO2, and pHa were 88–146 mmHg, 181–262mmHg, and 6.61–6.66, respectively.3.3. At recovery, the mean PaCO2, PaO2, and pHa were 15–31, 63–175 and 6.95–7.20 mmHg, respectively, the mean recovery time being 8–22 min.
The anesthetic action of CO2 was studied by examining the changes in the EEG, brain pH, and cerebral blood flow in carp subjected to 30-min hypercapnia at an anesthetic level (Pwco2 = 175 mm Hg) and subsequent 60-min normocapnia. The EEG of carp under hypercapnia gradually became smaller in amplitude with slowing of the wave and showed a tendency toward flatness. The cerebral blood flow transiently increased mainly due to an increase of the cerebral blood velocity under hypercapnia. During hypercapnia and the subsequent recovery period, the pattern of the pH at the brain surface was in good agreement with the pattern of the EEG, whereas the pattern of deep brain pH seemed to be correlated with the progression of anesthesia. These findings suggested that CO2 induced the impairment of the EEG by lowering the surface brain pH and exerted its anesthetic action by lowering deep brain pH.
Article
While ocean acidification is predicted to threaten marine biodiversity, the processes that directly impact species persistence are not well understood. For marine species, early life history stages are inherently vulnerable to predators and an innate ability to detect predators can be critical for survival. However, whether or not acidification inhibits predator detection is unknown. Here, we show that newly hatched larvae of the marine fish Amphiprion percula innately detect predators using olfactory cues and this ability is retained through to settlement. Aquarium-reared larvae, not previously exposed to predators, were able to distinguish between the olfactory cues of predatory and non-predatory species. However, when eggs and larvae were exposed to seawater simulating ocean acidification (pH 7.8 and 1000 p.p.m. CO2) settlement-stage larvae became strongly attracted to the smell of predators and the ability to discriminate between predators and non-predators was lost. Newly hatched larvae were unaffected by CO2 exposure and were still able to distinguish between predatory and non-predatory fish. If this impairment of olfactory preferences in settlement-stage larvae translates to higher mortality as a result of increased predation risk, there could be direct consequences for the replenishment and the sustainability of marine populations. Ecology Letters (2010) 13: 68–75
Article
We propose a general, nonlinear mixed effects model for repeated measures data and define estimators for its parameters. The proposed estimators are a natural combination of least squares estimators for nonlinear fixed effects models and maximum likelihood (or restricted maximum likelihood) estimators for linear mixed effects models. We implement Newton-Raphson estimation using previously developed computational methods for nonlinear fixed effects models and for linear mixed effects models. Two examples are presented and the connections between this work and recent work on generalized linear mixed effects models are discussed.
Article
Models for the analysis of longitudinal data must recognize the relationship between serial observations on the same unit. Multivariate models with general covariance structure are often difficult to apply to highly unbalanced data, whereas two-stage random-effects models can be used easily. In two-stage models, the probability distributions for the response vectors of different individuals belong to a single family, but some random-effects parameters vary across individuals, with a distribution specified at the second stage. A general family of models is discussed, which includes both growth models and repeated-measures models as special cases. A unified approach to fitting these models, based on a combination of empirical Bayes and maximum likelihood estimation of model parameters and using the EM algorithm, is discussed. Two examples are taken from a current epidemiological study of the health effects of air pollution.
Article
We present microspectrophotometric evidence for the existence of two distinct visual pigments residing in two different morphological types of photoreceptor of the sea lamprey. In the upstream migrant Petromyzon marinus, the pigment found in short receptors has a wavelength of peak absorbance (lambda max) of 525 nm, whereas the pigment located in long receptors has a lambda max of 600 nm. Although the former appears to be pure porphyropsin, the latter is akin to visual pigments found in the red-absorbing cones of amphibian and teleost retinae. The kinship is more than superficial pertaining to lambda max, however, because the long receptor pigment, like the others, shows the typical sensitivity to the anionic milieu. Lampreys belong to the class Cyclostomata, which now becomes the sixth phylogenetic class of vertebrates with anion-sensitive as well as anion-insensitive visual pigments. This finding strengthens the hypothesis that sensitivity to anions is an integral property of all long-wavelength-absorbing vertebrate pigments and that these pigments form a distinct group in which an external Cl- ion is utilized in tuning the lambda max of the alpha-band absorbance to its native maximum value. The presence of an anion-sensitive and an anion-insensitive pigment in a retina implies the expression of two distinct opsin genes. We infer this from several examples of correlation between anion sensitivity and opsin sequence groupings. Moreover, the presence of two distinct opsin genes expressed throughout six vertebrate classes implies their existence in a common ancestor to all.
Article
A new technology for treating waters contaminated with acid mine drainage involves the dissolution of limestone particles using carbon dioxide at pressures above ambient. Because of the fish health risks associated with episodes of high carbon dioxide levels in treated waters, we subjected three species of fish, brook trout (Salvelinus fontinalis), slimy sculpin (Cottus cognatus), and blacknose dace (Rhinichthys atratulus), to 24 h exposures of elevated dissolved carbon dioxide (CO2) at three levels, ranging from 1.0 (low) to 6.3 (high)%, under laboratory conditions. We measured blood physiological variables as well as behavior, including feeding responses, before, during, and after exposure. Physiological responses differed by species, but all species had elevated hematocrits after 1 h of exposure. Brook trout hematocritis were higher at medium and high levels of CO2 than in a control group (0.0% CO2) after 24 h of exposure. Slimy sculpin hematocrits were higher in medium- and high-level exposure groups than in controls after 1 h, but not after 24 h, of exposure. Blacknose dace hematocrits were higher in all three exposure groups than in controls after 1 h but only in medium-level exposure groups after 24 h. Brook trout plasma glucose was significantly higher in medium- and high-level exposure groups after 1 h, and in the high-level group after 24 h, than in controls. Slimy sculpin plasma glucose was not significantly different in elevated CO2 exposure groups from that of controls throughout exposure. Branchial ventilation was significantly greater in all species at elevated CO2 during exposure, indicating stress; however, no difference was observed between treatment and control groups of blacknose dace after 24 h, indicating acclimation. Pectoral fin beats and cough rates were not consistently related to CO2 exposure throughout the study. Brook trout had the longest lasting reaction to stress at lower levels of CO2 among the three species tested. Many of the 11 observed behavioral variables, related to swimming, feeding, social, and illness factors, were affected by elevations of dissolved CO2. Two to seven behavioral variables (18-64% of those measured) were affected by treatment level of dissolved CO2 with a trend by species for the number of variables affected: brook trout > blacknose dace > slimy sculpin. However, behavioral sensitivity to treatment level was greatest in blacknose dace. Recovery to pre-treatment activity rates for most behavior patterns (including feeding) was observed 24 h after cessation of exposure in all three species. Recovery was independent of treatment level, was most rapid in blacknose dace, and was slowest in brook trout. Overall, slimy sculpin was least affected behaviorally by elevated CO2. Although all three species showed stress response and changes in behavior at moderate levels of CO2 (> or = 2%), brook trout and blacknose dace showed evidence of ability to avoid harmful CO2 levels by swimming out of affected waters, whereas the slimy sculpin showed minimal behavioral changes despite remaining in place during exposure. Thus, predation risk and other sources of mortality seem minimal in the event of technological malfunction at a stream treatment site involving the use of CO2 under pressure.
Article
That ventilation in fish is driven by O2 has long been accepted. The O2 ventilatory drive reflects the much lower capacitance of water for O2 than for CO2, and is mediated by O2 receptors that are distributed throughout the gill arches and that monitor both internal and external O2 levels. In recent years, however, evidence has amassed in support of the existence of a ventilatory drive in fish that is keyed to CO2 and/or pH. While ventilatory responses to CO2/pH may be mediated in part by the O2 drive through CO2/pH-induced changes in blood O2 status, CO2/pH also appear to stimulate ventilation directly. The receptors involved in this pathway are as yet unknown, but the experimental evidence available to date supports the involvement of branchial CO2-sensitive chemoreceptors with an external orientation. Internally-oriented CO2-sensitive chemoreceptors may also be involved, although evidence on this point remains equivocal. In the present paper, the evidence for a CO2/pH-keyed ventilatory drive in fish will be reviewed.
Article
The Ecological Society of America has evaluated current U.S. national policies and practices on biological invasions in light of current scientific knowledge. Invasions by harmful nonnative species are increasing in number and area affected; the damages to ecosystems, economic activity, and human welfare are accumulating. Without improved strategies based on recent scientific advances and increased investments to counter invasions, harm from invasive species is likely to accelerate. Federal leadership, with the cooperation of state and local governments, is required to increase the effectiveness of prevention of invasions, detect and respond quickly to new potentially harmful invasions, control and slow the spread of existing invasions, and provide a national center to ensure that these efforts are coordinated and cost effective. Specifically, the Ecological Society of America recommends that the federal government take the following six actions: (1) Use new information and practices to better manage commercial and other pathways to reduce the transport and release of potentially harmful species; (2) Adopt more quantitative procedures for risk analysis and apply them to every species proposed for importation into the country; (3) Use new cost-effective diagnostic technologies to increase active surveillance and sharing of information about invasive species so that responses to new invasions can be more rapid and effective; (4) Create new legal authority and provide emergency funding to support rapid responses to emerging invasions; (5) Provide funding and incentives for cost-effective programs to slow the spread of existing invasive species in order to protect still uninvaded ecosystems, social and industrial infrastructure, and human welfare; and (6) Establish a National Center for Invasive Species Management (under the existing National Invasive Species Council) to coordinate and lead improvements in federal, state, and international policies on invasive species. Recent scientific and technical advances provide a sound basis for more cost-effective national responses to invasive species. Greater investments in improved technology and management practices would be more than repaid by reduced damages from current and future invasive species. The Ecological Society of America is committed to assist all levels of government and provide scientific advice to improve all aspects of invasive-species management.
Effects of freshwater hyperoxia and hypercapnia and their influences on subsequent seawater transfer in Atlantic salmon (Salmo salar) smolts
  • Brauner