Seasonal variations in the biochemical composition of the serum of Mytilus galloprovincialis Lmk. and its relationship to the reproductive cycle and parasitic load

The levels of carbohydrate and protein in the blood serum of mussels ( Mytilus galloprovincialis Lmk.) experimentally cultured at two depths in Galicia (NW Spain) were determined over a period of 1 year. The changes in concentration of total and reducing carbohydrate and protein exhibited an annual cycle; their values varied from 0.053 to 0.700 mg/ml, from 0.050 to 0.669 mg/ml and from 0.620 to 2.830 mg/ml respectively. Also, the concentrations of total carbohydrate and protein were greater in animals from 5 m depth than those from 2 m. Total and reducing carbohydrate were the components most affected by parasitism. The greatest effect on total carbohydrate concentration was detected in mussels affected by the parasites Mytilicola intestinalis and Marteilia refringens, which presented lower values in infected mussels than in non-infected ones, mainly in the summer months.