MICROBIOLOGICAL INDICATORS OF FECAL POLLUTION IN THE MOUTH OF OLHO D’ÁGUA TIDAL CREEK, PARANA: A SUBSIDY FOR MONITORING BALNEABILITY IN BRAZIL

Abstract

Contamination studies, through analyses of total and thermotolerant coliforms in recreation waters, are important for human health as for the environmental quality. The aim of this study was to analyze the abundance of the enterobacteria in the mouth of the Olho d'Água tidal creek and adjacent beach, in different tidal heights (high tide and low tide), correlating them with environmental parameters (salinity, temperature, potential hidrogenionic, dissolved oxygen and rainfall). Five samples of surface water in three points (one in the tidal creek and two in the adjacent beach), in high tide and low tide were collected between December 2003 and January 2005. The total coliforms and thermotolerants were determined by the multiple tubes method. Rainfall data and tidal heights were obtained from the Laboratory of Marine Physics of the Centro de Estudos do Mar/UFPR. In the studied period the smallest values of salinity, pH, dissolved oxygen and higher values of total coliforms and thermotolerants were recorded in the tidal creek. In the other points great reductions of these microorganisms were observed by the miscegenation of the tidal creek water with the water of the adjacent sea. Comparing all points, great differences were not verified in the coliforms variability among the tides. However, comparing the contamination of the beach only, fecal contamination was significantly higher (p = 0,039) during the low tide, mainly in the periods of high rainfall. It is suggested, therefore, that from now on sampling for monitoring balneability should consider the height of the tide and rainfall indexes.