The temporal and spatial relationship between stenotopic dwarf spiders (Erigoninae: Araneae) and their prey (Isotomidae: Collembola) in coastal grey dunes:: A numerical aggregative response or common microhabitat preference?

During 1999-2001, we investigated the spatial and temporal relationship between stenotopic dwarf spiders and their springtail prey in coastal grey dunes. This habitat is characterised by severe microclimatological fluctuations that influence the spatial and temporal distribution of epigeic invertebrates. In three types of grey dune vegetation, where spring-tails showed different temporal abundance patterns, a positive relationship was observed between the phenology of the palatable springtails and stenotopic dwarf spiders. In particular, the relationship with female spiders, which depend highly on prey for reproduction, was very significant. A similar spatial aggregation exists for both prey and predator. Their presence was influenced by the same soil and vegetation characteristics. Two mechanisms are assumed to be responsible for this similar distribution; a common, independently developed habitat preference or a numerical response from the spiders in the presence of prey. After correction for intra-correlations, the relationship between prey and predator was nonsignificant and hence more likely to be the result of common microhabitat preferences.