Environmental drivers - spatial and temporal variation of macroinvertebrate communities in island streams: the case of the Azores Archipelago

Freshwater systems on the volcanic oceanic islands of Macaronesia and the macroinvertebrate communities that occupy them differ strongly from European mainland systems. This is a result of their geological origin, relatively small size, catchment morphology and distance from potential sources of colonization. The spatial and temporal distribution patterns of benthic macroinvertebrate assemblages were assessed over two seasons at 23 sites in 13 streams across the Azores Archipelago. ANOSIM results indicated significant spatiotemporal differences in macroinvertebrate assemblages between islands. Links between environmental factors distributed over different spatial scales and macroinvertebrate assemblages were assessed using DISTLM, a linear model for distance-based multivariate analysis and partial redundancy analysis (pRDA). Latitude and island age complex largely explained macroinvertebrate composition at the regional scale, while drivers of change at the local scale were land use, temperature, conductivity and nutrient levels. Flow variation was identified as the principal factor driving temporal change in macroinvertebrate community patterns. The results of this study provide support for current and future stream ecosystem research and baseline information for developing integrated freshwater management strategies for streams on the Azorean archipelago.