Disentangling natural and anthropogenic influences on Patagonian pond water quality.

EPELE LUIS; MANZO LUZ; GRECH MARTA; MACCHI PABLO A; CLAVERIE ALFREDO; LAGOMARSINO L; MISERENDINO MARIA LAURA

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 p. 866 - 876

0048-9697

Patagonia is a vast sparsely-populated region which is located at the southern end of the South American continent. Patagonian ponds are a key component of urban and rural landscapes because they provide several ecosystem services such as habitat for wildlife and watering for livestock. Integrating field-based and geospatial data of 109 ponds sampled across the region, we identified spatial trends and assessed the effects of anthropogenic and natural factors in pond water quality. We tested the hypothesis that the effects of widespread human activities can override the effect of climate (natural variability) as driver of pond water quality. Ponds were classified among different natural (e.g. hydroperiod and hydrology) and anthropogenic (e.g. land use) classifications. Landscape and pond water data were included and simplified in two PCA analyses. The cut-off value that separate two different levels within main categories (e.g. reference vs. impacted) was estimate using receiver operating characteristic (ROC) curves. The studied ponds were generally shallow, well oxygenated, with maximum nutrient values reported in sites used for livestock breeding. TN:TP ratio values were lower than 14 in more than 90% of the ponds, indicating nitrogen limitation. To assess 35 Patagonian ponds water status we recommend the measure of total suspended solids and total nitrogen in the water, and evaluate the wetgrasses coverage in a 100 m radius from the pond, since those features were significantly influenced by human land use. Our findings pointed the importance of theforest and steppe biomes as the main responsible for the natural variability of thePatagonian ponds water status.