During an annual cycle, concentrations of free amino acids were determined in mussels, Mytilus edulis , collected monthly from 10 different locations in the Delta area (southwest part of the Netherlands). The applicability of suggested biochemical stress indices, i.e. the ratio of the taurine/glycine concentrations and the sum of the threonine and serine concentrations, was investigated. Due to large seasonal and environmental variations (reproduction, salinity etc.), these stress indices should be used with much care. |