Predation on fish larvae by moon jellyfish Aurelia aurita under low dissolved oxygen concentrations

Laboratory experiments were conducted to test the hypothesis that low dissolved oxygen concentrations have the potential to enhance the predation rate on fish larvae by moon jellyfish Aurelia aurita which is increasing in abundance in the coastal waters of Japan. Larvae of the red sea bream Pagrus m...

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Bibliographic Details
Published in:Fisheries science 2005-08, Vol.71 (4), p.748-753
Main Authors: Shoji, J. (Kyoto Univ. (Japan)), Masuda, R, Yamashita, Y, Tanaka, M
Format: Article
Language:English
Subjects:
ANOXIA
Aurelia aurita
Coastal waters
COELENTERATA
DISSOLVED OXYGEN
Fish
FISH LARVAE
hypoxia
jellyfish
Larvae
Oxygen
PAGRUS
PREDATION
Prey
red sea bream
Swimming
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Summary:Laboratory experiments were conducted to test the hypothesis that low dissolved oxygen concentrations have the potential to enhance the predation rate on fish larvae by moon jellyfish Aurelia aurita which is increasing in abundance in the coastal waters of Japan. Larvae of the red sea bream Pagrus major in four size classes (2.9, 4.1, 6.2 and 8.6 mm in standard length) were used as prey in a short-term predation experiment. No change in the bell contraction rate of the jellyfish (mean bell diameter, 100.4 +- 10.2 mm) was observed at the oxygen concentrations tested (1, 2 and 4 mg/L, and air-saturated, 5.5-6.0 mg/L), suggesting a strong tolerance to a decline in the oxygen concentration. More than 80% of the 2.5 and 4.1-mm size-class larvae were predated on by the jellyfish at all oxygen concentrations during the 15-min trials in 10-L tanks. The 6.2 and 8.6-mm size-class larvae were able to escape from the jellyfish apparently due to their developed swimming ability at the two higher dissolved oxygen concentrations. There was an increase in predation on larvae of these two size classes at the two lower dissolved oxygen concentrations. Predation by moon jellyfish on fish larvae can be more intense at low dissolved oxygen concentrations that commonly occur in the coastal waters of Japan.
ISSN:0919-9268
1444-2906
DOI:10.1111/j.1444-2906.2005.01024.x