Seasonal and spatial variability of macronutrients and Chlorophyll a based on GIS in the South American estuary (Bahia Blanca, Argentina)

ArGIS was used to obtain the knowledge of spatial variability of macronutrients and Chlorophyll a in different p arts of Bahia Blanca Estuary (BBE). Dissolved inorganic nitrogen, phosphorous and silicates associated with the seasonal pattern of Chlorophyll a, in the inner and the middle estuary of Bahia Blanca, are evaluated in this paper. During November 2008-September 2011, continuous samples of seawater were taken aboard the institutional boat, in the main Channel. Twenty-one stations in the inner and middle zone were studied. Physicochemical parameters were in situ measured. Surface water samples for nutrients, Chlorophyll a and phaeopigments analysis were collected. Phosphates levels increase during spring (3.24 mu mol L-1) in the outer station and minimum values were observed during winter in the inner stations (0.93 mu mol L-1). The maximum value of Chlorophyll a was observed in winter (13.17 mu g L-1) at middle stations, associated with minimum values of phosphates. Several changes have been observed in chemical and biological parameters found in the intermediate zone of BBE during the coldest months of the year. Keywords