Microbiological Pollution of Ria Formosa (South of Portugal) LIDIA PO CATALAO DIONISIO , G. RHEINHEIMERà and JUAN J. BORREGO§*  U.C.T.A., University of Algarve, Faro, Portugal àInstitute of Oceanography, University of Kiel, Kiel, Germany §Department of Microbiology, Faculty of Sciences, Campus Universitario Teatinos, University of Malaga, 29071 Malaga, Spain A 24-month survey on the microbiological quality of rec- reational shore marine waters in three sampling stations located at Ria Formosa (South of Portugal) was con- ducted. The classical indicators of faecal pollution, such as total coliforms (TC), faecal (thermotolerant) coliforms (FC), faecal streptococci (FS) and somatic coliphages, as well as several physico-chemical parameters (temperature, salinity, dissolved oxygen (DO) and transparency) were determined in the sampling stations, which exhibited dierent degrees of faecal pollution. The relationships between faecal indicators and several pathogenic micro- organisms (Salmonella, Pseudomonas aeruginosa and Candida albicans) were also established in these recre- ational marine zones. The results obtained indicate that none of the indicators tested may be considered as a uni- versal index of the presence of pathogens in water; how- ever, faecal streptococci showed a higher and signi®cant relationship with sewage discharges. Ó 2000 Elsevier Science Ltd. All rights reserved. Keywords: pollution; marine environment; faecal indica- tors; pathogenic microorganisms; water quality criteria; lagoon system. Introduction Telluric microorganisms are introduced into aquatic environments mainly by discharges of non-treated wastewater and sewage, that are the main sources of faecal pollution in natural aquatic environments (Wallis, 1977; Borrego and Figueras, 1997; Figueras et al., 1997). The discharged microorganisms are not able to grow in natural waters, and they die o after a short time period, due to the in¯uence of several biotic and abiotic factors which vary depending on the kind of water and the prevailing conditions (Borrego et al., 1983; Rheinhei- mer, 1992). Although several studies have been per- formed, the mechanisms aecting microbial die-o in aquatic environments are not well established yet (Fattal et al., 1983; Borrego and Romero, 1985; de Vicente et al., 1988; Mori ~ nigo et al., 1989; 1990; Cornax et al., 1990; Pereira and Alcantara, 1993). Faecal pollution of recreational waters may be a health hazard for bathers due to the presence of several microbial pathogens, including bacteria, viruses, fungi and protozoa (Moe, 1997). Routine analyses for these pathogenic microorganisms are very dicult to perform because of the diversity and complexity of their speci®c methodologies (Borrego, 1994). The presence of these microbial pathogens in natural waters are currently monitored using microbial indicators of faecal pollu- tion, such as total coliforms (TC), faecal coliforms (FC) and faecal streptococci (FS) (Dufour, 1984; Geldreich, 1997). However, a direct and consistent relationship between indicators and microbial pathogens has not been established yet (Cabelli et al., 1982; Ferley et al., 1989; Kay et al., 1994). Thus, the use of classical bac- terial indicators of water quality has been questioned (Borrego et al., 1983, Saliba and Helmer, 1990; Fewtrel and Jones, 1992; Borrego and Figueras, 1997). The main objective of the present work was to mon- itor Ria Formosa waters microbiologically to determine the relation among dierent groups of microorganisms in waters with dierent levels of faecal pollution. In addition, the in¯uence of several physico-chemical pa- rameters on the evolution of the microbial numbers in these waters was also studied. Materials and Methods Description of the study area and sampling The investigations were carried out in Ria Formosa, near Faro (South of Portugal) over a two-year period. Ria Formosa extends about 55 km from Ancao (37°1 0 30 00 N±8°2 0 30 00 W), and has a variable width that reaches 6 km from Faro to Santa Maria Cape. The submerged area is calculated to be about 11 800 Ha (Monteiro, 1989), and the area includes the towns of Faro, Olhao, Loule, Tavira and Vila Real de San Antonio. Marine Pollution Bulletin Vol. 40, No. 2, pp. 186±193, 2000 Ó 2000 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0025-326X/00 $ - see front matter PII: S0025-326X(99)00206-4 *Corresponding author. Tel.: +34-5-2131893; fax: +34-5-2132000. 186