Evaluation of the quality of coastal bathing waters in Spain through fecal bacteria Escherichia coli and Enterococcus

Abstract

Sun. and beach tourism is very important to the economy of Spain, so the control of the quality of the environment on the beaches is essential. Therefore, the analysis and control of the quality of bathing water is necessary, which is defined by the European Directive 2006/7/EC as excellent, good or sufficient depending on the presence of microbiological contamination or other organisms or waste presenting a risk to bathers' health. For that, 1392 beaches of the Iberian Peninsula and its islands were analysed, taking into account: fecal bacteria (Escherichia coli and Enterococcus), physical characteristics of sediment, level of urbanization, climatic and anthropogenic factors, and maritime climate. Thus, it was observed that urban sand beaches located in seas with fewer hours of sunshine and important tide have higher concentrations of E. coli and Enterococcus. There is also an indirect relationship between these microorganisms with salinity (R2 0.746 for E. coli and 0.606 for Enterococcus), temperature (R2 0.743 for E. coli and 0.604 for Enterococcus) and hours of sunshine (R2 0.781 for E. coli and 0.706 for Enterococcus), while this relationship is direct with rainfall (R2 0.640 for E. coli and 0.607 for Enterococcus) or wave height (R2 0.769 for E. coli and 0.601 for Enterococcus). From all this, it follows that the Directive 2006/7/EC should define more specific criteria as to the place and time of sampling, and take into account the different environment variables that influence the survival of bacteria, so that the results may reflect reality, and avoid staff responsible for sampling freely choose the place and time of sampling.