The impact of diets upon the fatty acid composition of haemocyte polar lipids and consequently upon immune parameters has been tested in the oyster Crassostrea gigas and the clam Ruditapes philippinarum. Oysters and clams were fed each of three cultured algae: Chaetoceros calcitrans, which is rich in 20:5(n-3) and 20:4(n-6) and poor in 22:6(n-3) fatty acids; T-Iso (Isochrysis sp.), which is rich in 22:6(n-3) and deficient in 20:5(n-3) and 20:4(n-6); and Tetraselmis suecica, which is deficient in 22:6(n-3) and contains only small amounts of 20:5(n-3) and 20:4(n-6).
Fatty acid composition of haemocyte polar lipids was greatly affected by the diet. Oysters and clams fed C. calcitrans maintained a higher proportion of 20:5(n-3) and 20:4(n-6) in their haemocyte polar lipids, while these polyunsaturated fatty acids decreased drastically for