SWIMMING KINEMATICS OF FAST STARTS ARE ALTERED BY TEMPERATURE- ACCLIMATION IN THE MARINE FISH MYOXOCEPHALUS-SCORPIUS

The swimming kinematics of prey capture was studied in short-horned sculpin (Myoxocephalus scorpius L.) acclimated for 6-8 weeks to either 5 degrees C or 15 degrees C (12h:12h light:dark) using 15 degrees C-acclimated shrimps as prey. Fish acclimated to 5 degrees C remained interested in feeding following an acute rise in temperature to 15 degrees C over 12h. Prey capture was a stereotyped behaviour consisting of stalking and stationary phases, followed by an S-shaped fast-start (stage 1), a propulsive stroke (stage 2) and a glide of variable duration during which the mouth was expanded and protruded to suck in the prey (stage 3). The duration of the preparatory stroke (half tail-beat, stage 1) was significantly shorter at 15 degrees C (48.8 ms) than at 5 degrees C (108.3 ms) in the 5 degrees C-acclimated sculpin (Q(10)=2.2). For 5 degrees C-acclimated fish, at 5 degrees C, the maximum values for acceleration and velocity along the path travelled by the fish were 16.2 ms(-2) and 0.8 ms(-1) respectively. Both variables were relatively independent of acute temperature change (Q(10)=1.1-1.2; P>0.1). At 15 degrees C, the maximum velocity was 33 % higher and the tail-beat duration of the propulsive stroke was 37 % shorter in 15 degrees C-acclimated than in 5 degrees C-acclimated fish. Both stride length and tail-beat amplitude were significantly higher (28 and 23 % respectively) in 15 degrees C- compared with 5 degrees C-acclimated sculpin at 15 degrees C. The results demonstrate plasticity in the major kinematic variables of fast-starts following warm acclimation sufficient to increase the percentage of successful attacks during prey capture from 23.2 to 73.4 %.