GROWTH AND BIOCHEMICAL COMPOSITION OF MYTILUS EDULIS WHEN REARED ON EFFLUENT FROM A COD, GADUS MORHUA, AQUACULTURE FACILITY

摘要

This study determined the growth and biochemical composition of blue mussels (Mytilus Mulls) reared on effluent from Atlantic cod (Gadus morhua) and compared it with mussels reared on a standard shellfish diet. Feeding trials lasted 6 mo, and mussels were sampled on a monthly basis. Dry weight, ash-free dry weight, shell length, and condition index were all significantly higher in algae-fed mussels at the end of the experiment compared with effluent-fed mussels. The carbon content decreased for mussels fed both diets; however, their nitrogen and protein content increased, with effluent-fed mussels having significantly more nitrogen and protein than algae-fed mussels, suggesting that effluent can increase mussel growth. Total lipid and fatty acid (FA) content decreased for effluent-fed mussels at the end of the experiment. There were no significant differences in the lipid class composition between mussels fed the 2 diets. Mussels fed both diets significantly decreased in the amount of 14:0,16:1 omega 7, 16:2 omega 4, 16:4 omega 1 and 20:5 omega 3, and effluent-fed mussels also decreased in 18:4 omega 3 and 21:5 omega 3, as well as increased in the amount of 17:1, the zooplankton markers 20:1 omega 11 and 22:1 omega 11, and the dienoic nonmethylene-interrupted fatty acids (NMIDs) 20:2a and 22:2b. Significant differences in the amount of individual FAs between mussels fed the 2 diets included a larger amount of I 8:2 omega 6 and 20:4 omega 6 in algae-fed mussels, and a significantly larger amount of 16:4 omega 1 in mussels fed effluent. Mussels fed both diets underwent significant increases in the proportion of bacterial FAs, omega 6 FAs, zooplankton markers, and NMIDs. Effluent-fed mussels had a significantly larger proportion of monounsaturated FAs, zooplankton markers, and NMIDs, as well as a smaller proportion of polyunsaturated FAs, and omega 3 and omega 6 FAs than algae-fed mussels. The increased presence of zooplankton markers supports the use of these FAs to track aquaculture wastes.