Organisation et evolution des peuplements lagunaires

The analysis of the community structures of a Danish fjord macrofauna and of various Mediterranean lagoons results in the same interpretation of the organization of communities which start from meroplankton, leading to the formation of disorganized communities. The biotic and abiotic lagoon environment puts these populations under stress, causing gradual organization into structured one-species communities. Such an interpretation suggests that the degree of organization is measured by the species diversity or more precisely by one species alone. Each population has to develop and adapt strategy which favors migratory behavior. When this is not possible, a waste economy develops where the speed of the generation cycles corrects the catastrophic losses resulting from climatic stress. The arguments are reasonably convincing when only the eco-ethologic behavior of the monospecific populations are studied. It is more difficult to accept them when we try to apply the same reasoning to pluri-specific communities.