Water mites (Acari, Hydrachnidia) in tropical springs — diversity, specificity, monitoring possibilities

Springs connecting groundwater with surface water systems show characteristic physico-chemical stability. They accommodate a distinctive fauna and flora, that significantly contributes to diversity. The habitat specificity, high diversity and indicative potential of spring dwelling water mites has been shown in many investigations from temperate regions (WILLIAMS & WILLIAMS 1996, CANTONATI et al. 2006). Corresponding data on the crenobiosis of aquatic invertebrates until recently were missing from tropica1 regions, GoLDSCHMIDT (2004) presented the first data on specific water mite assemblages in tropical springs. In a Canonical Correspondence Analysis (CCA) faunistic differentiation of Costa Rican water mite assemblages and the significance of particular parameters were analysed (GowscHMIDT 2004). Multivariate analysis of this data identified habitat type (especially springs), temperature, elevation and velocity as major factors determining water mite assemblages in Costa Rica and showed a distinct spring fauna (GOLDSCHMIDT 2004, submitted). Constant low temperature has long been regarded as crucial factor for the habitat binding of crenobionts, however recent authors have emphasized the general stabi1ity of their physicochemistry (FISCHER 1996, CANTONATI et al. 2006). Due to their specific temperature regime, tropical springs supply essential data for the understanding of crenobiosis in general. Furthermore they are of specific interest because of their stability over very Iong periods of time. The current study on Costa Rican water mites showed the importance oftropical springs, the specificity oftheir water mite assemblages and their suitability for the monitoring ofbiological integrity of spring habitats. These data provide a baseline for 1ong-term monitoring and demonstrate a need for further research.