Annual variations in the reproductive traits of Pomatoschistus microps in a Mediterranean lagoon undergoing environmental changes: evidence of phenotypic plasticity

The spawning period of the common goby Pomatoschistus microps from 1993 to 1997 in the Vaccares lagoon did not vary, except in 1997 when it was longer due to the reproduction of the young-of-the-year. Egg size and number, and reproductive allocation varied greatly with one year to another. Female co mmon gobies increased both their fecundity per spawning act and their egg s ize from 1993 to 1995. The annual variation in the reproductive effort sugg ests a high phenotypic plasticity of reproductive traits in P. microps, in the face of environmental perturbations. In winter 1993-1994, a centennial flood of the Rhone River caused major hydrological changes in the lagoon in less than 1 week, affecting many invertebrates and fish for several years. The reproductive investment of the common goby increased, possibly as a co nsequence of those environmental changes. (C) 2000 The Fisheries Society of the British Isles.