Effects of highly unsaturated fatty acids on escape ability from moon
jellyfish Aurelia aurita in red sea bream Pagrus major larvae
S.
Nakayama, R. Masuda, T. Takeuchi, M. Tanaka-2003
Fisheries
Science,
69(5): 903
Abstract:
The
development of escape behavior from moon jellyfish Aurelia aurita was
studied in the red sea bream Pagrus major larvae raised with two
distinct dietary regimes: one fed rotifers and Artemia nauplii
enriched with highly unsaturated fatty acids (the HUFA-enriched group); and
the other fed those without enrichment (the HUFA-deficient group). The
length of time that it took for a larva to be captured by three medusae of A. aurita
was measured. The observation was continued for 5 min. The capture time
was compared between the two dietary groups for the same age, and among
different ages within the same dietary group. The capture time in the
HUFA-enriched group was significantly longer on day 18 and day 20 compared
to the younger stages, whereas there was no such discernible developmental
changes in the HUFA-deficient group. The average capture time on day 18 in
the HUFA-enriched and HUFA-deficient groups was 277 and 161 s,
respectively, with almost the same body length (7.1 mm and 7.2 mm,
respectively). Fatty acid analysis revealed that rotifers and Artemia
in the HUFA-enriched group contained 2.2 and 0.6% of docosahexaenoic acid
(DHA) in dry weight, whereas those in the HUFA-deficient group did not
contain any detectable amount of DHA. Present work revealed that A. aurita
can be a potential predator of P. major up to lengths of 7.1 mm
(day 18) when the nutritional condition of the fish was good, and that the
threat can be serious up to larger sizes when the fish had experienced
inferior dietary conditions.
(Division of Applied Biosciences, Graduate School of
Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan, Tel:
81-773-62-9063.Fax: 81-773-62-5513. Email of R. Masuda: reiji@kais.kyoto-u.ac.jp)