Characterising the role of the sea-surface microlayer in regulating microbial dispersal, human exposure, and pollutant transformation

The sea-surface microlayer (SML) is the topmost 10mm of a marine body of water. It mediates all the gaseous, particulate and chemical exchanges between the seawater and the atmosphere. As a transitional ecosystem, it is uniquely characterised by the accumulation of hydrophobic chemicals, oil slicks and extreme physical parameters (e.g. high UV irradiation, large temperature fluctuations) and has been shown to support unique assemblages of microbes that can be either beneficial or harmful for humans, plants and animals. Understanding the SML is therefore essential for identifying and quantifying ecosystem threats in any coastal marine community. This proposal aims to fill a critical knowledge gap and employ a multidisciplinary approach, ranging from molecular taxonomy to ecological modelling, to understand, for the first time, the fundamental role of the SML in the tropics. The project will leverage the complementary expertise of the two PI’s in the ecology of the atmosphere and the hydrosphere and will employ the latest advancements in sampling methodology and genomic sequencing. Using a recently developed method for single cell viral characterisation we aim to enumerate the virally infected cells in the SML and will use laboratory microcosms for manipulative experiments of air-sea exchanges under future climate scenarios. All the results will be mapped back to specific anthropogenic impacts and integrated into ecological models that will help quantifying the risk that the SML might have on the health of humans, plants and animals on the Singapore coastline. In doing so, this research will not only answer fundamental questions in microbial physiology, adaptation to extreme environments and evolution, but also the way for effective global strategy of a sustained, multidisciplinary and integrated observation of the SML in tropical waters.