The environmental framework of temporary ponds: A tropical-mediterranean comparison

Temporary ponds are distributed worldwide, providing significant ecological services. Their limnological features are influenced by a set of regional (mainly climate) and local (natural or anthropogenic) factors. To evaluate the differences in their ecological functioning in distant geographic regions, we analysed the main features of 90 temporary ponds located in three distinct areas: two mediterranean-climate regions (Eastern Iberian Peninsula and Central Chile) and a tropical setting in Costa Rica. Each pond was surveyed thrice during the hydrological cycle of 2017-2018, and five sets of parameters were obtained: limnological, hydrogeomorphological, biotic, landscape and climatic variables. Through multivariate analyses, we determined the environmental heterogeneity of each region and the main environmental differences among them. As expected, hydrogeomorphological factors did not differ between regions, but climate variables showed marked differences between the tropical and the two mediterranean regions. We also detected clear differences between mediterranean and tropical ponds in terms of their mineralization patterns (mainly conductivity and alkalinity), natural vegetation cover and land use. Despite the regional similarities between mediterranean regions, some strong differences were found concerning vegetation cover, nutrient concentration and trophic state, probably associated to human activities (agriculture and extensive stockbreeding).