The Biodiverse Surface

Anna Rees

When you think of life in the ocean, coral reefs and tidepools might be what comes to mind. The ocean’s surface, though, may be the key to understanding the ocean’s diversity and what it can tell us about climate change.

While it may appear that nothing is living on the surface, in reality it is amazingly biodiverse. The habitat that is the surface of the ocean is rich in sunlight and reaches about 1 meter deep. Free living organisms on the surface of the ocean are called “Neuston”, and include many organisms crucial to the marine ecosystem, such as floating barnacles, snails, and seaweed species. Other organisms rely on these neuston to survive; the Loggerhead turtle’s diet, for example, is 80% neuston. There is organism variability across different regions of the ocean, and the species are not uniformly distributed. For example, the Sargasso sea is one of the more well-researched areas, and many organisms live only on the surface in this region, specifically adapted to live on the neustonic seaweed.

The surface of the ocean is not only a place of rich biodiversity, it is also at the front lines of the effects of climate change. Pollution, oil spills, and plastic litter all impact the surface’s ecosystem first, so changes here can help predict changes below the surface. Industries on land also play a part in altering the surface’s ecosystem. Logging, which has reduced the amount of wood floating out to the open ocean, has reduced the amount of shelter available for these organisms. Understanding the changes that are happening to the surface’s ecosystem is essential to understanding the extent of our impacts on the ocean as a whole.

Despite the ocean’s surface having wonderful richness in diversity and being of critical importance to the ocean’s health, it is an understudied part of marine biology, and there is still so much to learn about it. It’s likely already significantly different than what it was a few hundred years ago due to climate change and other human effects.

Helm RR. The mysterious ecosystem at the ocean's surface. Plos Biology. 2021 Apr;19(4):e3001046. DOI: 10.1371/journal.pbio.3001046. PMID: 33909611; PMCID: PMC8081451.