The movement of Bighead Carp (Hypopthalmichthus nobilis), an invasive aquatic nuisance species, through the Chicago Area Waterway System may lead to their introduction into the Great Lakes causing cascading ecological effects. Elevated carbon dioxide (CO2) levels are proposed as a method for deterring carp dispersal into the Great Lakes. To increase our knowledge of the efficacy of CO2 deterrent systems, we studied the effects of four levels of free CO2 on Bighead Carp shoaling and swimming behavior, including ambient control (12 mg CO2/l; 78 ?atm), low (30 mg CO2/l; 5,855 ?atm), medium (60 mg CO 2/l; 15,707 μatm), and high (90 mg CO2/l; 27,665 μatm) treatments. We compared changes in average nearest neighbor distance (NND), inter-individual distance (IID), and swim velocity across five consecutive stages (ambient baseline, CO2 injection, CO2 treatment exposure, freshwater injection, and freshwater recovery) within each treatment and between similar stages of each treatment. We found that the average nearest neighbor distance (NND) and inter-individual distance (IID) increased by 168% and 143%, respectively, when exposed to the high CO2 treatment relative to the control treatment. Carp swimming performance decreased by 29% when exposed to the medium CO2 treatment relative to the control, but not when exposed to the high CO2 treatment. Comparing within treatment differences between the ambient baseline stage and CO2 exposure stage, NND increased by 45% for the medium treatment and 207% for the high treatment. Within treatment IID increased for all elevated CO 2 treatments, by 14% for the low treatment, 52% for the medium treatment, and 198% for the high treatment. The increase in spatial distribution at elevated CO2 levels indicated a decline in the ability of carp to maintain group structure; thus, affecting social feedback systems. The results of this study are important for the design and implementation of CO2 deterrent systems because the optimal strategy of fish would be to pass through such deterrents quickly in order to minimize the risk of immediate threats and reduce migration delays that may have negative consequences on fitness. Elevated CO2 concentrations (>90 mg CO2/l) not only disrupts the ability of the group to use collective orientation for beneficial navigation, it may also disrupt swimming performance.
|Advisor:||Fangue, Nann A.|
|Commitee:||Fangue, Nann A., Todgham, Anne, Woodley, Christa M.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||MAI 58/04M(E), Masters Abstracts International|
|Subjects:||Animal sciences, Behavioral Sciences, Physiology|
|Keywords:||Asian carp, Behavior, Co2, Grouping, Shoaling|
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