SMALL-SCALE TURBULENCE AND ZOOPLANKTON METABOLISM - EFFECTS OF TURBULENCE ON HEARTBEAT RATES OF PLANKTONIC CRUSTACEANS

The effects of small-scale turbulence on heartbeat rate (HBR), an estimator of zooplankton metabolism, have been determined in some fresh-water and marine planktonic crustaceans. Quantified levels of turbulence (approximately 5 mm2 s-3) enhanced HBR in Daphnia by 14.3% compared to calm water conditions. Supplementary observations with four other species showed that these species also had higher HBR in turbulent than in calm situations, the average percent increase ranging from approximately 5% in a marine cladoceran (Penilia avirrostris) to 93% in a marine copepod (female Calanus gracilis). These results agree with previous studies that indicated a relevant effect of small-scale turbulence on behavior and rate processes of planktonic crustaceans.