We evaluated the efficacy of carbon dioxide (CO2) for preventing settlement of the biofouling quagga mussel (Dreissena bugensis) in raw water systems. Trials were conducted in a mobile laboratory located at the US Bureau of Reclamation, Davis Dam Hydropower Facility, and supplied with raw water from the Colorado River. Incoming water was split between five chambers where CO2 was dissolved into the water at five concentrations. Chamber outflows were mixed with raw water which was infested with quagga larvae (veligers) and then delivered to test tanks containing settlement plates. We conducted two 18-d trials; trial 1 tested continuous infusion with (target concentrations) 30, 45, 60, 75, and 100 mg/L dCO2. Trial 2 evaluated intermittent infusion schedules: 24 h on/off with 50, 75, and 100 mg/L dCO2 and 24 h once/week with 100 mg/L dCO2. At the end of each trial, we counted the number of settled quagga on plates in each treatment and modeled predicted settlement, relative to untreated water, by CO2 treatment.

Resource agencies are searching for effective methods to prevent the spread of invasive Silver Carp (Hypophthalmichthys molitrix) and Bighead Carp (Hypophthalmichthys nobilis), hereafter bigheaded carps, from the Mississippi River basin into the Laurentian Great Lakes. Elevating carbon dioxide (CO2) concentrations in water within locks and other pinch points is an approach being considered to reduce invasive fish passage. Laboratory studies have shown that bigheaded carps strongly avoid areas of elevated CO2 (Kates et al. 2012; Dennis et al. 2015). Similarly, telemetry studies found that CO2 can be used to exclude bigheaded carps from certain locations (Donaldson et al. 2016) and reduce upstream movement (Cupp et al. 2016). Previous studies were completed under controlled settings, and research to determine the feasibility and efficacy of elevated CO2 to control bigheaded carp movements in larger natural environments is needed. On October 21–28, 2016, the U.S. Geological Survey Upper Midwest Environmental Sciences Center, Illinois-Iowa Water Science Center, and Columbia Environmental Research Center conducted a short field study at Emiquon Preserve (15T 750386.95m E, 4469041.70m N) near Havana, IL. Objectives for this study were to (1) characterize CO2 concentrations and distribution at various water velocities and (2) determine the effectiveness of CO2 to reduce general fish abundance and movement. During this study, water quality, atmospheric CO2, and fish presence were quantified across three water velocities (no flow, restricted flow, and unrestricted flow) with and without CO2 injection. The study was conducted at the water management structures (WMS) which served at the single connection between an isolated backwater lake and the Illinois River. Carbon dioxide was injected into the downstream portion of the WMS using air diffusers connected to compressed CO2 tanks. Fish abundance and movement was quantified using two Adaptive Resolution Imaging Sonar (ARIS) transducers placed across WMS entrances. Water quality was quantified using stationary sondes, grab sample, and mobile transects. Atmospheric CO2 concentrations were quantified at fixed locations throughout the study site. Dates and times of importance: no water flow with CO2 start (21OCT2016 0800 CDT) and stop (21OCT2016 1600 CDT), modified flow with CO2 start (25OCT2016 0800 CDT) and stop (25OCT2016 1600 CDT), unrestricted flow with CO2 start (24OCT2016 0800 CDT) and stop (24OCT2016 1600 CDT), no flow control day without CO2 (28OCT2016), modified flow control day without CO2 (27OCT2016), and unrestricted flow control day without CO2 (23OCT2016).

Resource agencies are searching for effective methods to prevent the spread of invasive Silver Carp (Hypophthalmichthys molitrix) and Bighead Carp (Hypophthalmichthys nobilis), hereafter bigheaded carps, from the Mississippi River basin into the Laurentian Great Lakes. Elevating carbon dioxide (CO2) concentrations in water within locks and other pinch points is an approach being considered to reduce invasive fish passage. Laboratory studies have shown that bigheaded carps strongly avoid areas of elevated CO2 (Kates et al. 2012; Dennis et al. 2015). Similarly, telemetry studies found that CO2 can be used to exclude bigheaded carps from certain locations (Donaldson et al. 2016) and reduce upstream movement (Cupp et al. 2016). Previous studies were completed under controlled settings, and research to determine the feasibility and efficacy of elevated CO2 to control bigheaded carp movements in larger natural environments is needed. On October 21–28, 2016, the U.S. Geological Survey Upper Midwest Environmental Sciences Center, Illinois-Iowa Water Science Center, and Columbia Environmental Research Center conducted a short field study at Emiquon Preserve (15T 750386.95m E, 4469041.70m N) near Havana, IL. Objectives for this study were to (1) characterize CO2 concentrations and distribution at various water velocities and (2) determine the effectiveness of CO2 to reduce general fish abundance and movement. During this study, water quality, atmospheric CO2, and fish presence were quantified across three water velocities (no flow, restricted flow, and unrestricted flow) with and without CO2 injection. The study was conducted at the water management structures (WMS) which served at the single connection between an isolated backwater lake and the Illinois River. Carbon dioxide was injected into the downstream portion of the WMS using air diffusers connected to compressed CO2 tanks. Fish abundance and movement was quantified using two Adaptive Resolution Imaging Sonar (ARIS) transducers placed across WMS entrances. Water quality was quantified using stationary sondes, grab sample, and mobile transects. Atmospheric CO2 concentrations were quantified at fixed locations throughout the study site. Dates and times of importance: no water flow with CO2 start (21OCT2016 0800 CDT) and stop (21OCT2016 1600 CDT), modified flow with CO2 start (25OCT2016 0800 CDT) and stop (25OCT2016 1600 CDT), unrestricted flow with CO2 start (24OCT2016 0800 CDT) and stop (24OCT2016 1600 CDT), no flow control day without CO2 (28OCT2016), modified flow control day without CO2 (27OCT2016), and unrestricted flow control day without CO2 (23OCT2016).

Control technology for dreissenid mussels (Dreissena polymorpha and D. bugensis) currently relies heavily on chemical molluscicides that can be both costly and ecologically harmful. There is a need to develop more environmentally neutral control tools to manage dreissenid mussels, particularly in cooler water. Carbon dioxide has been shown to be lethal to several species of invasive bivalves, including zebra mussels and Asian clams (Corbicula fluminea). We evaluated the effects of various treatment regimes [i.e., exposure duration and pCO2 (partial pressure of carbon dioxide)] on mortality, byssal thread formation and attachment, and narcotization behavior. The effects of elevated carbon dioxide on nontarget native freshwater mussel Lampsilis siliquoidea were also measured. Results of trials conducted at 12°C indicated that carbon dioxide exposure induced narcotization behavior and reduced attachment of zebra mussels within 24 h. An extended exposure duration (96 h) produced 80-100% mortality of zebra mussels, and was safe to juvenile L. siliquoidea mussels. The results indicate that carbon dioxide could be used in an integrated pest management program for dreissenid mussels

Control technology for dreissenid mussels (Dreissena polymorpha and D. bugensis) currently relies heavily on chemical molluscicides that can be both costly and ecologically harmful. There is a need to develop more environmentally neutral control tools to manage dreissenid mussels, particularly in cooler water. Carbon dioxide has been shown to be lethal to several species of invasive bivalves, including zebra mussels and Asian clams (Corbicula fluminea). We evaluated the effects of various treatment regimes [i.e., exposure duration and pCO2 (partial pressure of carbon dioxide)] on mortality, byssal thread formation and attachment, and narcotization behavior. The effects of elevated carbon dioxide on nontarget native freshwater mussel Lampsilis siliquoidea were also measured. Results of trials conducted at 12°C indicated that carbon dioxide exposure induced narcotization behavior and reduced attachment of zebra mussels within 24 h. An extended exposure duration (96 h) produced 80-100% mortality of zebra mussels, and was safe to juvenile L. siliquoidea mussels. The results indicate that carbon dioxide could be used in an integrated pest management program for dreissenid mussels

This study evaluated carbon dioxide (CO2) injected into water as a possible behavioral stimulant to enhance capture and removal of invasive red swamp crayfish (RSC, Procambarus clarkii Girard, 1852) from a retention pond in southeastern Michigan. Objectives of this study were to (1) determine if target CO2 concentrations were attainable within the infested pond, and (2) determine if CO2 treatment was effective to push RSC towards shorelines or onto dry land where they could be collected and removed. Carbon dioxide was applied directly into one treatment pond (~2,500 m3) in Novi, MI. Two nearby ponds in Livonia, MI were used as untreated control ponds. Crayfish removal efficiency was evaluated in all ponds using baited traps and shoreline surveys. Results showed that the CO2 treatment pond reached its target concentration of >200 milligrams per liter (mg/L) CO2, a benchmark determined from previous laboratory studies, approximately 11 hours after injection started and was maintained between 200-351 mg/L CO2 for approximately 2.5 days. During treatment, some emergent crayfish were observed near influent culverts around the pond, possibly indicative of a behavioral response. However, the number of individuals and crayfish observations were minimal and infrequent. Crayfish continued to be removed throughout CO2 treatment with baited traps and perimeter surveys, but differences in catch rates between the treatment and control ponds were not apparent and confounded by a temporal decline in catch rates across all ponds. Overall, this study demonstrated that open-water treatment applications with CO2 are possible, but its effectiveness to enhance RSC removal was unclear due to limited crayfish observations.

This study evaluated carbon dioxide (CO2) injected into water as a possible behavioral stimulant to enhance capture and removal of invasive red swamp crayfish (RSC, Procambarus clarkii Girard, 1852) from a retention pond in southeastern Michigan. Objectives of this study were to (1) determine if target CO2 concentrations were attainable within the infested pond, and (2) determine if CO2 treatment was effective to push RSC towards shorelines or onto dry land where they could be collected and removed. Carbon dioxide was applied directly into one treatment pond (~2,500 m3) in Novi, MI. Two nearby ponds in Livonia, MI were used as untreated control ponds. Crayfish removal efficiency was evaluated in all ponds using baited traps and shoreline surveys. Results showed that the CO2 treatment pond reached its target concentration of >200 milligrams per liter (mg/L) CO2, a benchmark determined from previous laboratory studies, approximately 11 hours after injection started and was maintained between 200-351 mg/L CO2 for approximately 2.5 days. During treatment, some emergent crayfish were observed near influent culverts around the pond, possibly indicative of a behavioral response. However, the number of individuals and crayfish observations were minimal and infrequent. Crayfish continued to be removed throughout CO2 treatment with baited traps and perimeter surveys, but differences in catch rates between the treatment and control ponds were not apparent and confounded by a temporal decline in catch rates across all ponds. Overall, this study demonstrated that open-water treatment applications with CO2 are possible, but its effectiveness to enhance RSC removal was unclear due to limited crayfish observations.

Locks and dams are possible management points to block the spread of invasive Asian carps in the United States. Infusion of carbon dioxide (CO2) into water is one deterrent strategy being considered at navigational structures to reduce upstream fish passage that would not directly interfere with lock and dam operations. The goal of this study was to determine lethal concentrations of CO2 to non-target species. Bluegill (Lepomis macrochirus) and Fathead minnows (Pimephales promelas) were exposed to CO2 continuously for 12 hours using a diluter system. Trials were performed on both species at target water temperatures of 5, 15, and 25°C. See related manuscript for additional details on experimental methods.

Locks and dams are possible management points to block the spread of invasive Asian carps in the United States. Infusion of carbon dioxide (CO2) into water is one deterrent strategy being considered at navigational structures to reduce upstream fish passage that would not directly interfere with lock and dam operations. The goal of this study was to determine lethal concentrations of CO2 to non-target species. Bluegill (Lepomis macrochirus) and Fathead minnows (Pimephales promelas) were exposed to CO2 continuously for 12 hours using a diluter system. Trials were performed on both species at target water temperatures of 5, 15, and 25°C. See related manuscript for additional details on experimental methods.

The capacity of wetlands to mitigate greenhouse gas (GHG) emissions is the sum of two services–the protection of vulnerable organic stocks from remineralisation, and the capacity to sequester GHGs relative to their anthropogenic replacements. Organic carbon accumulation (CA) down through the sediment column is often taken as the measure of sequestration because of its capacity to record long-term variability and trends. However, we demonstrate that: i) CA is not equivalent to sequestration as net ecosystem production (NEP) for open systems; it requires the subtraction of the initial deposition rate of labile allochthonous carbon sources; ii) CA also requires subtraction of intrinsically allochthonous recalcitrants down through the sediment column, and together with subtraction of autochthonous recalcitrants from organic stock services; iii) CA as a climatic mitigation service also requires a diagenetic correction, as the annual deposition of labile organic carbon continues to remineralise over the long-term; and iv) preserving of a wetland has a significantly greater mitigation potential than restoring one. To address the above concerns, a global diagenetic solution is proposed, applied, and tested for a tropical seagrass and mangrove. As expected traditional CA estimates were disproportionately larger than their respective cal. NEPs and together with stocks fell within the ranges reported in the literature, with a final carbon accreditation highly dependent on the choice of their anthropogenic replacements. The review demonstrates that mitigation concepts and measurements for natural carbon sequestration solutions require re-evaluation to avoid GHG emissions above their capacity or reduce the ability to fulfil emission targets.