Changes In Swimming Activity Of Jenynsia Multidentata Fed With Microcystin-RR. New Evidences On The Energetic Cost Of Detoxication.

CAZENAVE, J.; NORES, M.L.; MICELI, M.; DÍAZ, M. P.; WUNDERLIN, D. A.; BISTONI, M.A.

Los Cocos. Córdoba

Simposio; I° Simposio SETAC Argentina, Ecotoxicologia Y Contaminación.; 2006

SETAC AR

We report the effects of sublethal doses of microcystin-RR (MC-RR) on swimming activity of Jenynsia multidentata as well as the simultaneous response of its detoxication system by measuring Glutathion S-transferase (GST) activities in liver and brain of fish. MC-RR was applied on the food pellets at doses of 0.01, 0.1 and 1 ìg·g-1. Swimming activity was recorded by using a computer-based image processing system, which affords several issues representative of fish behaviour (average velocity, movement percentage). Results show that low levels of cyanotoxin increased the swimming activity (average velocity and movement percentage), while the highest dose used produced significant changes with respect to control group only during the last hours of exposure, when the swimming activity was decreased. On the other hand, GST activity was significantly increased only in liver and brain of fish fed with the highest MC-RR dose. Both results suggest that fish are reacting to the stress caused by low doses of MC-RR by increasing their swimming activity, raising further questions on the probable neurotoxicity of MCs, and presenting the behavioural change as a good biomarker of early toxic stress as well. On the other hand, at the highest MC-RR dose, when the detoxication activity began, it seems that fish uses its energy to eliminate the toxin instead of increasing its swimming activity, giving additional evidences on the energetic cost involved in the biotransformation of MCs.