Animal metacommunities of temporary ponds in a flat grassland landscape of Uruguay

In October 2008, ponds were sampled with a dipnet (15 x 20 cm, 1 mm mesh) through a standardised routine in which five equidistant samples were taken along the two main orthogonal axes of most of the ponds. To account for the range of pond areas, which exhibits differences in several orders of magnitude (from 6.6 m2 to 24,673 m2) when the quadrants were closer than two meters, the number of sampled units was reduced, and if the quadrants were more than 10 meters apart, then the number of sampled units was increased. The samples were washed, coarse separated, and preserved in 95% alcohol for identification. Individuals were classified with the highest possible taxonomic resolution. In cases where it was not possible to achieve a higher taxonomic resolution, individuals were assigned to taxa easily separable by morphological differences (i.e. morphospecies or the lowest possible hierarchy category). Each individual was measured with a digital caliper (to the nearest 0.01 mm). Environmental data Depth was measured at least 10 times in major and minor axes. The volume of the pond was estimated as the volume of an oval using the length of the major and minor axes of the ponds and the mean depth. Heterogeneity was estimated as the number of 'islands', emergent mounds above water level, per meter of the main and minor axes of the ponds. Vegetation biomass corresponds to standing biomass per unit sample—400 cm2 (20 x 20 cm). Vegetation species richness is the total richness of plants in a pond. The shape was approximated as the major/minor axis ratio. Geographical coordinates, latitude, and longitude of each pond were recorded.