The Effects of Seaweed Diets on the Growth, Lipid and Fatty Acids of Juveniles of the White Sea Urchin Tripneustes gratilla

Abstract

The effects of seaweed diets on the growth and biochemical composition of the white sea urchin Tripneustes gratilla were studied using three seaweeds with different fatty acid (FA) profiles: Ulva pertusa (green alga, high in 16:4n-3, 18:3n-3, and 18:4n-3 polyunsaturated fatty acids or PUFAs), Gloiopeltis furcata (red alga, rich in 20:4n-6 and 20:5n-3 PUFAs) and Undaria pinnatifida (brown alga, abundant in 18:3n-3, 18:4n-3, 20:4n-6, and 20:5n-3 PUFAs). Specific growth rates (dry weight basis) were the highest in the animals fed Undaria (including the mixed algal diet), followed by Ulva and Gloiopeltis. The highest feed conversion efficiencies (on a dry weight basis) were with Undaria (80.0%) and Ulva (76.6%) while the lowest was with Gloiopeltis (51.5%). All algal diets did not affect the major lipid classes of the sea urchin tissues. The poor growth rates associated with a seaweed diet deficient in 18:3n-3, 18:4n-3, or 20:4n-6 (such as Gloiopeltis and Ulva) suggest that these FAs may be essential for juveniles of the white sea urchin.