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Respiratory and Circulatory Adjustments during Aquatic Treadmill Exercise in the European Shore Crab Carcinus Maenas
1 Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen, Scotland AB9 2TN; CTI Centre for Biology, Donnan Laboratories, University of Liverpool, Liverpool, L69 3BX
2 Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen, Scotland AB9 2TN
Carcinus maenas (L.) were exercised using a novel design of aquatic treadmill respirometer. Tethered exercise was performed in sea water at 5.8 m min-1 for 5min. The rate of oxygen consumption and the heart and scaphognathite beat rates increased at the onset of exercise, reaching a steady state within 180 s. The estimated haemolymph flow rate rose 2.6-fold during exercise, achieved by a 1.8-fold increase in heart rate and a 1.5-fold increase in the estimated cardiac stroke volume. The haemolymph total oxygen content difference increased significantly during exercise. Haemolymph total carbon dioxide content did not change significantly during exerise, but haemolymph pH deceased as a result of an L-lactate-induced metabolic acidosis. The acidosis may also have led to a reduced Bohr shift. It is concluded that O2 and CO2 exchange were not impaired during exercise and that C. maenas relied primarily upon O2 to fuel underwater running at 5.8 m min-1.
Key words: Carcinus maenas, crabs, exercise, respiration, circulation, treadmill
Accepted on September 13, 1991
