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Starvation of the Respiratory Metabolism and Locomotion of Aurelia aurita s.l. Ephyrae

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Document pages: 16 pages

Abstract: Blooms of the scyphozoan jellyfish Aurelia aurita are greatly regulated by the survival rate of planktonic ephyrae. Theecophysiology of ephyrae is poorly studied compared with polyps and medusae. Asextremely strong starvation resistance and recovery capability of A. aurita ephyrae may due to its low metabolic rate as well as starvation may reduce theswimming ability of ephyrae which may lead to the higher predation loss, theeffects of temperature and starvation on their respiration and pulsation rateswere examined. In this study, ephyrae under different starvation conditionswere measured by a fluorescence-based DO meter after 72 h incubation. And thepulsation rates were measured at every 10-d interval in 1-liter plastic bottleby a hand-held counter. The results showed that the mean respiration rates ofnewly released ephyrae were 0.24, 0.24 and 0.19 μl O2 ephyra-1 d-1 at 15°C, 12°C and 9°C, respectively, and the rates tended todecrease with increasing starvation duration. Carbon weight-specificrespiration rates did not change significantly with starvation duration. Thedry weight-specific respiration rates of newly released A. aurita ephyrae (i.e., 11.7-14.6 μl O2 mg DW-1 d-1) were nearly oneorder of magnitude lower than the rates for planktonic larvae of other taxa(e.g., molluscs, crustaceans and fish). The maximum pulsation rate taken by A.aurita ephyrae was 49.2 beats min-1, which represents themaximum swimming velocity to be 8.87 cm·min-1. The pulsation rateswere not affected by temperature over the range between 9°C and 15°C. However,they were influenced by starvation duration. Starvation-derived decrease inpulsation together with associated body shrinkage may lead to lower encounterrate of prey and lower escaping ability from predators, which may lead tohigher predation loss in the field.

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