Assessing the impact of agricultural activities on the Lagoon of Varano (South Italy) through remote sensing approach

Coastal lagoons and ponds are areas where sea water and fresh water mix, forming brackish water. They represent 13% of coastal environments worldwide and one of the most productive ecosystems in the biosphere. Lagoons are support a diversity of wildlife by providing habitat for shelter, food and reproduction. However, the delicate balance of these environments is easily threatened by anthropogenic impacts because characteristics such as weak hydrodynamism and limited turnover make lagoons sensitive to such impacts placing severe stress on the entire ecosystem. Varano Lagoon is located along the southern Adriatic coast (Italy) near the Gargano promontory (41.88Nord;15.75East). The lagoon has an average depth of 4 m, with maximum of 5 m in the central zone. The aim of this paper is to analyze the spatial and temporal variability of limnological, physical and chemical parameters (pH, temperature, dissolved oxygen, salinity, nutrients and chlorophyll a) of the lagoon using a remote sensing approach. Chemical and physical measurements were performed in summer and spring in 2004 and 2005 and correlated with Landsat 7 TM data. The distribution of the chlorophyll a and main nutrients were made at high spectral resolution. Reflectance data from the lagoon as well as surrounding catchment were analysed and compared to estimate concentrations (chlorophyll a, nutrients, suspended solids, temperature and chlorophyll a) and the variation of the lagoon water level in order to understand all the chemical dynamic inside.