A video-based movement analysis system to quantify behavioral stress responses of individual and groups of fish

A.S. Kane^1,2, J.D. Salierno¹ and G.T. Gipson¹

¹Aquatic Pathobiology Laboratory, Department of Veterinary Medicine, University of Maryland, MD, USA
²Virgina-Maryland Regional College of Veterinary Medicine, MD, USA

Behavioral alterations can serve as quantitative endpoints of sub-lethal toxicity, and provide a valuable tool for environmental risk assessment. A video analysis system and software algorithms were designed to investigate stress- and contaminant-induced behavioral alterations in fish, using a mummichog (Fundulus heteroclitus) model. The videography system automatically recorded individual and group .sh behavior in twelve 20-L exposure arenas at multiple and discrete intervals throughout an experimental period. Two experimental paradigms are presented to illustrate the system: acclimation over time and exposure to an anesthetic MS-222 (40 and 60 mg/L). The system software transformed x,y coordinate movement data into relevant behavioral endpoints. These endpoints included velocity, burst frequency, total distance traveled, angular change, percent movement, space utilization, fractal dimension (path complexity), interactions, schooling, shoaling, and aggregations. Results from the acclimation study demonstrated initial hyperactivity followed by decreased activity that leveled out at 24-h and remained consistent through 72- h. MS-222 exposure resulted in significant alterations in individual, schooling, and shoaling behaviors. There was a significant increase in individual activity including movement, velocity and burst frequency, and a decrease in fractal dimension. In contrast, there was a significant decrease in group interactions and shoaling behaviors. Further, MS-222 exposed fish no longer exhibited schooling behavior. These changes in behaviors resulting from MS- 222 exposure are consistent with low level anesthesia. This system provides flexibility to analyze any observed behavior, is remotely controlled, and can be transported. Movement endpoints discerned by this system can be used to identify characteristic behavioral responses to a variety of stressors at environmentally-relevant concentrations, and assist in risk assessment and the development of more sensitive Lowest Observable Effect Levels (NOELs) and No Observable Effect Levels (NOELs) for a variety of sentinel species.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.

© 2005 Noldus Information Technology bv