Sediment characteristics and microbiological contamination of beach sand – A case–study in the archipelago of Madeira

Abstract

Beach sand can harbour pathogenic and opportunistic microorganisms, as well as faecal indicator bacteria that influence directly the bathing water quality. Pathogenic and opportunistic microorganisms often raise concern of exposure during beach related recreational activities. In this work, three different types of sandy beaches (natural basaltic, natural calcareous and artificial calcareous) of the Archipelago of Madeira (Portugal) were sampled for bacterial and fungal contaminants and grain size distribution, during four years (2010-2013). Following an extreme weather event in 2010, the faecal indicator bacteria levels spiked, returning to base levels shortly thereafter. The same phenomenon occurred with fungi, where potentially pathogenic fungi were the dominant group. Yeast-like fungi and dermatophytes were, however, mainly associated to months of higher usage by recreational users. Statistical analysis showed higher contamination of sediment in artificial beaches compared to natural beaches and granulometry and chemical composition of sand did not influence in the microbial loads. Instead, bather density and the influence of coastal protection structures needed to maintain the volume of artificial beach sand regarding the removal potential of wave induced currents are obvious influencing factors.

Fungi in sands of Mediterranean Sea beaches of Israel—Potential relevance to human health and well‐being

“…30,31 We could not detect the presence of dermatophytes in the Israeli beach sands, which possibly might be due to the high temperature of the sands. The presence of dermatophytes was reported rather scarcely in the literature, 32,33 and might be associated with specific ecological conditions, such as those found on the Madeira archipelago. 32 Sabino et al 33 faster, more accurate and can be performed by non-experts in the field of fungal morphology.…”

Impacts of a Changing Earth on Microbial Dynamics and Human Health Risks in the Continuum between Beach Water and Sand

“…Similarly, at a beach that underwent renovation, replacing calcium carbonate dominated sand with quartz sand (Hernandez et al 2014), substantial decreases were observed in FIB levels in both the sand and adjacent surface water, suggesting that calcium carbonate particles retain EPS and FIB more readily in comparison to quartz. However, other cases have reported that mineralogy may not influence FIB releases from sand, such as is the case reported by Abreu et al (2016) for beaches in Madeira, Portugal.…”

“…Similarly, Yamahara et al (2007) found that sheltered beaches in California had higher FIB than open ocean beaches with higher wave energy. Abreu et al (2016) observed higher microbial loading at beaches with artificial infrastructure designed to embay and protect them in the Madeira Archipelago. The amount of biofilm on sand particles, as measured by EPS levels, appears to be related to wave energy (Piggot et al 2012).…”

“…Both human and non-human contamination sources can cause health risks. FIB can also reach the beach sand-water continuum from extra-intestinal reservoirs, such as deposition and growth on algae or macrophytes, or via soil and sediment erosion from stormwater runoff (e.g., soil (Abreu et al 2016, O'Mullan et al 2017). Beaches with denser amounts of seaweed and filamentous green algae, can have higher levels of FIB (Anderson et al 1997, Quilliam et al 2014.…”

“…Factors such as beach morphology, orientation, sand granulometry and chemistry, land use, and infrastructure can have substantial impacts on both the amount of contamination in the water that can be exchanged at the sand-water continuum and beach microbial community structure. Microbial dynamics at beaches are also affected by hydrometeorological trends (Gronewold et al 2016), changes to the trophic state and turbidity of water (Binding et al 2015, Weiskerger andWhitman 2018), and by short-and long-term climate changes (Abreu et al 2016, Whitehead et al 2009).…”