Polyunsaturated fatty acids
in total lipid and phospholipids of chilean scallop Argopecten purpuratus
(L.) larvae: effects of diet and temperature
A. Farías, J.G. Bell, I. Uriarte, J.R. Sargent-2003
Aquaculture, 228(1-4): 289-305
Abstract:
The composition of lipids and fatty acids of larval
scallop Argopecten purpuratus were determined when cultured at one of
two temperatures and using one of the three algal diets. Larvae grown at 12
°C had the lowest values of phosphatidylcholine (PC) and highest values of
cholesterol and steryl esters (SE). The ratio of triacylglycerol
(TAG)/cholesterol was affected by temperature but not by diet and the lowest
values were observed in larvae grown at 12 °C. By using the ratio of
TAG/cholesterol as an index of larval condition, the best condition was
observed at the begining of the experiment, before feeding, with values of
3.9 and 2.9 in eggs and D-larvae, respectively. The best culture conditions
for larval scallop from this point of view was a temperature of 19 °C and a
diet of Isochrysis galbana grown at 25 °C while the poorest
condition was observed in larvae cultured at 12 °C and 19 °C and fed the
mixture of Isochrysis aff galbana (clone T-Iso) high-protein
and Chaetoceros neogracile high-protein (IH/GH diet). However, no
significant differences in the growth rate and survival of larvae fed
different diets were detected. I. galbana grown at 25 °C had no
detectable percentage of arachidonic acid (ARA; 20:4n-6), but larvae
grew well and ARA was detected in PC and phosphatidylethanolamine (PE) in
similar quantities to other diets. This suggests ARA may not be essential
during early life stages of larval Chilean scallops. Total lipids and PC of
larvae were affected by the diet in their ratio of docosahexaenoic acid
(DHA; 22:6n-3)/eicosapentaenoic acid (EPA; 20:5n-3), but PE
composition was highly conserved and was unaffected by diet. DHA/EPA ratio
in total lipid and in PC showed highest values when larvae were fed I.
galbana grown at 25 °C. Temperature affected the total highly
unsaturated fatty acids (HUFA) in total lipids, PC and PE of larvae. In all
cases values were lowest when larvae were cultured at 12 °C. In addition,
increased temperature increased the ratio of EPA/ARA in PC and decreased the
ratio of monounsaturated fatty acids (MUFA)/saturated fatty acids in PE. The
ratio of n-6/n-3 PUFA was constant in total lipid, PE and PC
of larval scallops regardless of temperature or diet.
(Instituto de Acuicultura, Facultad de Pesquerías y
Oceanografía, Universidad Austral de Chile, P.O. Box 1327, Puerto Montt,
Chile, e-mail: afarias@uach.cl)