Population rates of the three dominant amphipod species (Hyale nigra, Caprella danileviskii and Caprella penantis) associated to Bryocladia thrysigera, were calculated revealing similar values for the intrinsic growth rate. The empirical data modeled presented a good fit to the May-Leonard three-species competition model in a discrete Ricker form with periodic cycles for the carrying capacity. In adjusting model to data, a new method to calculate competition coefficients emerged in good agreement with ecological and behavior particularities. A simulation of environmental stochasticity was achieved by the insertion of random parameters for the calculation of each species carrying capacity. H. nigra presented a persistent behavior in extreme environmental stress, whereas C. penantis is highly sensitive to stress.
Amphipoda; Environmental Stress and Stochasticity; Population Dynamics; Three-Species Competition Model