Nutrient and plankton dynamics in a Mediterranean salt marsh dominated by incidents of flooding. Part 2: Response of the zooplankton community to disturbances

Abstract

The composition of the zooplankton community which colonizes some temporary basins in the salt marshes of the Aiguamolls de l'Emporda (NE Spain) was studied. The structure of the zooplankton community depends mainly on natural and anthropogenic disturbances, which are irregular and highly variable both in their nature and intensity. Six environmental situations with a regular community structure have been identified by means of correspondence analysis (CA) (each dominated by a characteristic species or taxon). The temporal pattern is described by the temporal positioning sequence of each basin in the CA and is modelled as displacements between the six aforementioned situations. The first three CA axes relate to, respectively, the intensity of inundation (i.e. the entry of external energy), the complexity of the Zooplankton community, and special conditions of water confinement. As the natural hydric dynamics lead the system towards desiccation (situation of minimum external energy), the CA community representation tends to converge towards the origin of the coordinates. On the other hand, disturbances can be considered as supplies of external energy. By their effect on the zooplankton community structure, disturbances produce three main divergent displacements in the CA factor space depending on the nature and intensity of the disturbance (pulse, press or desiccation).