Why scale matters? Life connections in the littoral of remote

In low nutrient alpine lakes, littoral surfaces are the most productive part of the ecosystem, and they are biodiversity 16 hotspots. It is not entirely known how the nature and properties of lake surrounding catchments, their ecological 17 structure and larger landscape factors work together at different scales to shape the structure and functioning of 18 littoral ecosystems. 19 A total of 114 high altitude lakes and ponds in the central Pyrenees were surveyed to assess the relative 20 control of catchment properties at a variety of scales on littoral zoobenthic communities. At each location benthic 21 invertebrate composition was recorded together with geolocation (altitude, latitude and longitude), composite factors 22 representing hydrodynamics, geo-morphology and topography, riparian vegetation composition, presence of 23 vertebrate predators (trout and frogs), and water pH and conductivity. 24 A two-step fuzzy set ordination (FSO)-multidimensional FSO (MFSO) model integrating benthic biota and 25 environmental variables revealed that at geographic scale, longitude gradient surpassed altitude in its influence on 26 littoral ecosystem, reflecting a transition between Atlantic and Mediteranean biogeographic regions. Within each 27 catchment, topography (through its control of catchment type, shore and catchment snow coverage, and connectivity 28 with other lakes) was the main driver of taxa composition, while hydrodynamics (waterbody size, type and 29 inflow/outflow volumes) was secondary, and strongly covaried with the former. Locally, riparian plant composition 30 was tightly connected with littoral invertebrate community structure, richness and morphotype diversity. These 31 variables work directly and indirectly by creating habitats (for both, aquatic and terrestrial invertebrate stages), 32