Lipid composition of abalone was examined over a one-year interval. A feeding trial was designed to cover a full reproductive cycle in young adult green abalone, Haliotis fulgens, consisting of five diet treatments: the macrophytic algal phaeophyte Egregia menziesii, rhodophyte Chondracanthus canaliculatus, chlorophyte Ulva lobata, a composite of the three algae and a starvation control. The lipid class, fatty acid, sterol and 1-O-alkyl glyceryl ether profiles were determined for foot, hepatopancreas/gonad tissues and larvae. The major fatty acids were 16:0, 18:0, 18:1(n-7)c, 18:1(n-9)c, 20:4(n-6), 20:5(n-3) and 22:5(n-3), as well as 14:0 for abalone fed brown and red algae. 4,8,12-Trimethyltridecanoic acid, derived from algae, was detected for the first time in H. fulgens (hepatopancreas complex, 1.2-13.9%; larvae, 0.5% of total fatty acids). Diacylglyceryl ethers were present in larvae (0.6% of total lipid). The major 1-O-alkyl glycerols were 16:0, 16:1 and 18:0. Additionally, 18:1(n-9) was a major component in hepatopancreas/gonad and larvae. The major sterol was cholesterol (96-100% of total sterols). Highest growth rates were linked to temperature and occurred in abalone fed the phaeophyte E. menziesii (43 microm.day(-1), 56 mg.day(-1) yearly mean), an alga containing the highest levels of C(20) polyunsaturated fatty acids and the highest ratio of 20:4(n-6) to 20:5(n-3). This study provides evidence of the influence of diet and temperature on seasonal changes in abalone lipid profiles, where diet is most strongly related to body mass and temperature to shell length. The allocation of lipids to specific tissues in green abalone clarifies their lipid metabolism. These results provide a basis for improving nutrition of abalone in mariculture through formulation of artificial feeds.