Nutrients and carbon in some Mediterranean dune ponds

Abstract

Nutrients and carbon were studied in the temporary and permanent dune ponds of one of the few restored Mediterranean dune systems. The results indicate that small, low nutrient dune ponds can have a relevant role for carbon storage and processing, especially in the limestone areas. Despite the low percentage of organic matter in the sediment and water nutrient concentrations, most of the ponds had supersaturated carbon dioxide partial pressure levels with concentrations in half of them greater than the mean global value for lakes. Concentrations gradually decreased from old to newly restored ponds and with the presence of submerged plants. Carbon content was greater in temporary ponds. DOC was half of the mean global value for lakes. Particulate forms of nutrients and dissolved inorganic carbon predominated. Organic matter was a key variable for storage of nutrients and carbon in the sediment. Flooding of the ponds significantly reduced total organic carbon in the sediment by about 60%, but did not change significantly the concentrations of nitrogen and phosphorus. However, about 25% of organic matter and 37% of nitrogen accumulated in the sediment during consecutive summer droughts. Benthic algae incorporated part of the sediment nutrient pool after flooding.