Staphylococcus aureus is a pathogenic bacteria known to be a human health threat present in coastal recreational waters. Sewage effluent can contain and encourage the growth of of S. aureus. Abundance of S. aureus in coastal waters worldwide, as well as their association with known sewage indicators are not well documented. The aim of this study was to quantify abundance of S. aureus in coastal waters and examine its associations with sewage indicators. To do this, shoreline water samples were collected at low tide once a month at five stations along the coast of Puakō, Hawaiʻi over nine months, and analyzed for S. aureus and fecal indicators: Clostridium perfringens and Enterococcus, δ15N in macroalgal tissue, and nutrients.
Results/Conclusions
S. aureus was present in coastal waters at Puakō, Hawaiʻi, with counts ranging from 5 – 290 CFU/100 mL. Counts were not similar among stations and no station had average counts exceed 100 CFU/100mL, the level associated with increased infection rates among recreational water users. However, there were two instances where counts were above this threshold.
Additionally, counts of S. aureus were not associated with C. perfringens, Enterococcus, δ15N, or nutrients suggesting that sewage is not a source of S. aureus at Puakō. While shedding from S. aureus from swimmers is thought to be a source at crowded beaches, few people were observed at our stations. Our results suggest that S. aureus is present in coastal waters at Puakō and that more work is needed to determine its source(s) and ecological role.