Impact of algal diets and
emulsions on the fatty acid composition and content of selected tissues of
adult broodstock of the Chilean scallop Argopecten pupuratus
(Lamarck, 1819)
M.
Caers, P. Coutteau, P. Sorgeloos, G. Gajardo-2002
Aquaculture, 217(1-4): 437-452
Abstract:
The impact of dietary fatty acids on the fatty acid
composition and content in different organs (digestive gland, adductor
muscle and male and female gonad) of Argopecten purpuratus was
evaluated during the process of gonad maturation under controlled laboratory
conditions. A mixed algal diet of Isochrysis galbana (clone T-Iso), Pavlova
lutheri, Chaetoceros gracilis and Tetraselmis suecica was
either fed alone (Al) or supplemented with 50% lipids (expressed as % of the
algal dry weight (DW)) using an emulsion rich in 22:6n-3 (Al+EmDHA)
or an emulsion rich in 20:5n-3 (Al+EmEPA). Results showed the algal
diet having the greatest impact on the fatty acid composition (mainly an
increase of 18:1n-9, 18:2n-6; 18:3n-3 and a decrease of
20:5n-3) of the digestive gland and female gonad, moderate in the
male gonad while the fatty acid composition of the adductor muscle was
hardly affected. Our data indicated that 16:1n-7 and 18:1n-9
were partially elongated to 18:1n-7 and 20:1n-9, respectively.
The supplementation of the algal diet with EmDHA or EmEPA (which contained
45% and 19% 22:6n-3, respectively) increased significantly the
concentration of 22:6n-3 (mg g-1 DW) in the digestive
gland, female gonad and male gonad with 78%, 57% and 51%, respectively, for
(Al+EmDHA)-fed scallops and 18%, 33% and 19%, respectively, for
(Al+EmEPA)-fed scallops, while the 22:6n-3 concentration in the
adductor muscle was not affected. Broodstock conditioning was associated
with a significant increase of the lipid content in the female and to a
lesser extent in the male gonad. The significant increase (as compared to
the initial sample) of the 22:6n-3 concentration in the digestive
gland, female gonad and eggs of A. purpuratus fed 22:6n-3-rich
lipid illustrated that recently ingested fatty acids did significantly
contribute to the lipid accumulation process in the maturing female gonad.
The similarities between the fatty acid composition of the female gonad and
digestive gland suggest that lipids were transferred from the lipid-rich
digestive gland to the female gonad.
(Laboratory of Aquaculture and Artemia Reference
Center, University of Ghent, Rozier 44, B-9000, Ghent, Belgium, e-mail of P.
Sorgeloos: patrick.sorgeloos@rug.ac.be)