The typology of shapes of series (TSS) aims to gather together species having similar temporal patterns corresponding to different types of ecological behaviour. Each type of change, referred to as the ecological shape, is considered to reflect a particular demographic strategy (sudden pullulation of opportunistic species, fluctuations with environmental changes, etc.). This method which consists in the definition of four shape parameters and a classification among the series, taking into account these shape parameters, does not replace the usual statistical analyses, mainly multivariate ones, but precedes them. Such preliminary information is useful for the choice of the subsequent treatments, avoiding the need to analyse simultaneously species presenting distinct types of ecological responses. The TSS method was applied to four macrobenthic communities of the English Channel and the south of the North Sea, sampled from 1977 to 1992. Clustering among the ecological shapes revealed six different groups. Analysis of species lacking abundance (very scarce or absent during at least five years) and of species presenting high anomalies (higher than three standard deviatiations) showed thar ecological responses of this type can be related To environmental factors such as temperature, atmospheric pressure or the ''Amoco Cadiz'' oil spill in 1978.