Abstract

The first investigations of marine neuston (surface-dwelling organisms) were conducted in the 1950s and focused on the taxonomic diversity and abundance of organisms. Later investigators examined the physics, chemistry and exchange processes between the atmosphere and ocean. Today, we know the ocean–atmosphere interface is important for many biogeochemical processes essential for life.

Physical, chemical and biological conditions differ greatly between the uppermost 5 cm of the ocean and the water below. The marine pleuston includes the larger siphonophores, Physalia and Velella, which float on the surface. Neuston can be divided into epineuston and hyponeuston. The epineuston includes more than 40 species of water striders, Halobates, inhabiting the open ocean and coastal areas. The hyponeuston are organisms in the surface centilayer including hydrozoa, molluscs, copepods, isopods, decapod crustaceans, fishes, and the seaweed Sargassum.

The neuston connect the sea surface and water column as larvae develop and migrate downward, and adult animals visit the surface to feed and reproduce. The sea surface has become a site of significant enrichment of pollutants from terrestrial and atmospheric sources. The spatial coincidence of the maximum pollutant concentrations and the biological sensitivity of its inhabitants creates a critical situation in the marine environment.

High densities of neustonic organisms in the sea surface can influence air–sea exchange processes (as discussed in Chapter 10, this volume).