Temperature constrains locomotion and muscle function in two temperate labrids.

Area of Science:

• Physiological ecology
• Comparative physiology
• Aquatic animal locomotion

Background:

• Understanding the physiological mechanisms behind fish winter dormancy is crucial for predicting climate change impacts.
• Temperature significantly influences fish physiology, particularly muscle function and locomotion.

Purpose of the Study:

• To investigate how winter acclimation temperatures affect steady swimming and muscle contraction kinetics in cunner (Tautogolabrus adspersus).
• To compare the thermal performance of locomotor muscles between cunner and tautog (Tautoga onitis).

Main Methods:

• Fishes were acclimated to four temperatures (5, 10, 15, 20°C).
• Gait transition speed and fin beat frequency were measured.
• Muscle contraction kinetics (twitch and tetanus) were recorded from aerobic locomotor muscle.

Main Results:

• Fish acclimated to colder temperatures (5, 10°C) exhibited lower gait transition speeds.
• Muscle twitch kinetics were slower in fish acclimated at temperatures ≤10°C.
• Cunner locomotor muscle demonstrated faster contraction and relaxation than tautog muscle at 5 and 10°C.

Conclusions:

• Winter temperatures impose physiological stress on fish locomotor musculature, impacting locomotion.
• Cunner locomotor muscles exhibit greater thermal plasticity, allowing for better performance across a wider temperature range compared to tautog.
• Differences in muscle acclimation may contribute to the distinct overwintering ecologies and latitudinal distributions of these closely related species.