Swash Zone Interstitial Water is a reservoir of fungal microorganisms in a Mediterranean beach (Genoa city, Italy)

The swash zone interstitial water (SZIW) which occupies interstices, or spaces between the sand grains at the shoreline is suspected of accumulating microbes and thus of posing a health risk for beach users. In this study we examined the presence and concentrations of filamentous fungi and yeasts in SZIW and compared the results to the fungal densities found in the beach sand at three sampling locations along a Mediterranean beach (Sturla Beach, Genoa City, Italy). Unexpectedly SZIW had the highest counts of total filamentous fungi and yeasts while sand samples always displayed lower counts. SZIW also harboured a high fungal diversity with 10 genera and 74 different strains isolated from this matrix while only 8 genera and 47 different strains were isolated from the beach sand samples. Overall data from this study suggest that SZIW may constitute an important reservoir of fungal microorganisms in the beach environment.