Monitoring in Nuevo Gulf (Argentina): analysis of oceanographic data by geographic information systems (GIS)
Solis, Miriam Edith
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As a consequence of the human activities in coastal areas, the demand for goods and services from renewable and non-renewable marine resources is enlarged. However, generally, the production ofthese goods and services may affect and also be affected by the deterioration ofthe quality of marine waters. The Nuevo Gulf is a semi-enclosed basin located on the Patagonian coast of Argentina. This area is not heavily populated (about 50,000 inhabitants) but suffers from the common problems of coastal areas under the increasing pressure of human activities. A water quality assessment programme has become relevant to maintain the natural value ofthe place and to ensure the sustainability of growing economic activities, such as for example, tourism. Therefore, it is necessary toknow the characteristics ofthe waterbody and its seasonal and spatial variability, in order to set up future monitoring programmes for assessment. In this work, a seasonal and spatial analysis of an oceanographic data set (dissolved oxygen, nitrate, nitrite and phosphate, chlorophyll "a", temperature and salinity) collected in the Gulf during 1982-1983, has been carried out. The aim was to characterize the waterbody and to define spatial and seasonal partems to be applied to the se1ection of sites and frequencies of samplings, respectively. The analysis was mainly carried out by using a geographic information system (GIS). From the analysis, the system was characterized as temperate. Different vertical and horizontal partems were observed in each season. In the vertical dimension, winter is represented by homogeneous distribution of the variables, summer by stratified conditions and autumn and spring, by transitional stages towards vertical homogenization and build up of a thermocline, respectively. From the horizontal distributions, it was observed that in the westem and northwestem coast, lower nutrient levels are observed in most seasons. Sites and frequencies of samplings, are suggested for the design of a network for background monitoring or evaluation ofpresent and future eutrophication. It is recommended to set water quality standards for the Gulf, to use GIS and remote sensing images to leam more about the system and to improve the monitoring efforts. Finally, the monitoring should not be seen as an end in itselfbut as a dynamic and practical means to test and adjust management decisions.