Sea Foam Parties - A Hotspot for Pathogenic Microbes?

Marine foams are highly underexplored microbial habitats at the air-sea interface, where their occurrence is patchy and generally short-lived. Rahlff et al. (2019) provides the first comparison of the bacterial community composition of foams, sea-surface microlayer (SML) and seawater collected from 1m depth via flow-cytometry and DNA-based amplicon sequencing. In conclusion, foams are highly compressed versions of the SML due to increased cell numbers and SAS concentration. Bacterial taxa found in the foam were also present in the SML; in one particular site, Vibrio, Salmonella, as well as faecal coliforms such as E. coli were found in high proportions within the foam, as well as in lower amounts in the remaining sites. A general awareness for the presence of pathogens in sea foams can benefit public health and the recreational value of coastal areas and beaches where foams frequently occur.

Studying the microbial composition at the air-sea interface aids our understanding of air-sea exchange and bacterial transport processes. One limitation of this study is that the primer set employed during analysis had limited coverage and did not include sequences assigned to chloroplasts, mitochondria, eukaryotes and Archaea which limits the accuracy of these results by excluding potentially important groups. This phenomena requires further exploration to understand their ecological implications for the functioning of the marine food web, biogeochemical cycles and human health. 

Rahlff, J., Herlemann, D., Giebel, H.A., Mustaffa, N.I.H., Wurl, O. and Stolle, C., 2019. Marine foams represent compressed sea-surface microlayer with distinctive bacterial communities. bioRxiv, p.820696. This article can be found at: https://www.biorxiv.org/content/10.1101/820696v1.full