The effect of dietary carotenoids on gonad production
and carotenoid profiles in the sea urchin Lytechinus variegatus
L.R.
Plank, J.M. Lawrence, A.L. Lawrence, R.M. Olvera-2002
Journal
of the World Aquaculture Society, 33(2): 127-137 (from Current Contents)
Abstract :
Although
dietary carotenoids are generally considered important in sea urchin
aquaculture only for their effect on gonad color, they also have important
biological roles. The effects of dietary carotenoids on gonad production and
organ carotenoid profiles of Lytechinus variegatus were examined.
Individuals were collected in January 1999 and fed a replete diet with a
level of 0.60 mg carotenoids/kg for 4 wk, followed by one of four prepared
diets for 8 wk: one without supplemental carotenoids, one with beta-carotene
(16.92 mg carotenoids/kg feed), and two carotenoid mixtures, one high in
zeaxanthin (5.28 mg carotenoids/kg feed) and another high in capsanthin
(9.63 mg carotenoids/kg feed). The carotenoid profiles of the body
compartments differed. The primary carotenoid in gonads of males and females
was echinenone. The carotenoid profile of the test was similar to that of
the gonad. The carotenoid profile of the gut varied with diet, but was not
identical to composition of the diet. The gut profiles included echinenone
but at lower concentrations than in the gonad and test. The carotenoid
profile in the gut probably results from the presence of the carotenoids
absorbed and those metabolized. The results suggest that several pathways
exist to metabolize dietary carotenoids and that some of them are in the
gut. The concentration of carotenoids in the gut (g wet weight) was higher
than that of the gonad, which was higher than that of the test. The gonads
increased significantly in size regardless of diet, indicating carotenoids;
are not required for gonad production under the conditions of this
experiment. Although the concentration of carotenoids in the gonad decreased
over time, the absolute amount of carotenoids increased with the increase in
gonad size. Either gonad growth was more rapid than carotenoid deposition or
differential deposition in nutritive cells and gametogenic cells occurred,
or the amount of carotenoids used in the diets was too low to have an
effect.
(Univ S Florida; Dept Biol; 4202 E Fowler Ave, SCA 110; Tampa; FL 33620; USA)