The Oceans’ Floating Life: Charming Tiny Sea Creatures Inhabit Clean Waters and Garbage Patches Alike
Roberta Attanasio, Georgia State University
The oceans’ surface thrives with life. Myriad fascinating little animals gang together to form enigmatic ecosystems immersed in water and sunlight. The marine biologist Alister Hardy called them “The Blue Fleet,” to indicate the common blue color of the many swimming and floating organisms that make up these complex communities, now called the neuston. Wind, waves and water currents propel the diverse creatures around, which are a food source for seabirds, turtles and fish migrating from the deep layers.
There are cnidarians of the Velella velella species, also known as By-the-Wind Sailor. These jellyfish-like creatures are seasonally abundant and commonly wash up on beaches during the spring and summer. They’re disc-shaped hydrozoans with tentacles that hang down from the body. Thanks to a sort of clear sail centrally located, By-the-Wind Sailor are transported by the wind. Equally captivating is the Portuguese man-of-war (Physalia physalis), so-called because it resembles an 18th-century Portuguese warship under full sail. It can be recognized by a blue, violet or pink balloon-like float, which rises up to six inches above the waterline. The float hides long strands of tentacles containing microscopic capsules loaded with coiled, barbed tubes that deliver venom to paralyze and kill prey. Then, there are the five species of the ocean spider skater Halobates, peppercorn-sized insects that manage to walk on the surface of the water by exploiting its artificial tension. They can be found on almost half the ocean surface around the globe, making them one of the most widely distributed insects in the world.
There are many more neuston species—their variety is astonishing. For those not acquainted with this ecosystem, the best place to find out more is the 2021 article “The Mysterious Ecosystem at the Ocean’s Surface” by Rebecca Helm. She explains that the ocean’s surface acts like a skin between the atmosphere above and the water below. As ocean’s surface inhabitants, neuston are key ecological links connecting ecosystems as far ranging as coral reefs, islands, the deep sea and even freshwater habitats. In an article published in The Atlantic, Helm says, “I once stumbled upon a raft of neuston when a storm blew it ashore in California. Many neustonic animals are vibrant highlighter colors, and the sand was saturated in bright blues and pale pinks. Together, these small creatures may function like upside-down coral reefs: an oasis of shelter and life far out to sea.”
In a recent interview with the SETAC Globe, Helm recalled that when she ran into these animals for the first time in California, she was collecting plastic debris on the beach. One of the pieces had an odd shape—it resembled a little egg with three protruding fins and rings all over. After careful observation, she realized it was the skeleton of a By-the-Wind Sailor. She picked up several of them, noticing that their texture is similar to those of old Coca-Cola plastic bottles. The resemblance of plastic debris to these creatures may explain why animals such as sea turtles end up ingesting so much of it. Indeed, sea turtles are at significant risk of ingesting plastic at all stages of their lifecycle, resulting in potentially lethal consequences.
Even today, relatively little is known about neuston organisms. Helm says: “We see them washing up on the coast, and we have a community science project running up, gathering all the people that see them. On the water surface the tiny neuston creatures blend in, it’s like chasing bubbles. On the beach, they stand up with their bright blues and pinks and are very easy to see.” The project is NASA-funded, and combines community scientists with professional biologists and oceanographers to locate hotspots of ocean surface life. It’s called Global Ocean Surface Ecosystem Alliance (GO-SEA). It relies on passionate ocean-lovers to visit the sea and look for marine life, especially floating surface life.
But neuston are also found far beyond the shore, in the massive ocean gyres. Gyres are large systems of circular ocean current formed by Earth’s wind patterns, along with forces created by the rotation of the planet. Their movement helps drive the ocean conveyor belt, which circulates ocean water around the Earth and is essential for regulating temperature, salinity and nutrient flow. The circular currents constantly drag debris into their centers—large areas of stationary, calm water. Due to the area’s lack of movement, debris such as floating wood, seaweed, plastic and waste dumped from ocean vessels accumulate in them for years, creating the so-called garbage patches.
The removal of floating plastic debris from the garbage patches can minimize potentially adverse effects on neuston and other marine life. However, looking at it from another point of view, it’s also possible to envision benefits that plastic debris can provide, such as increased surface area for oviposition and structure for habitat. As of now, there are large uncertainties in our understanding of how plastic impacts the dynamics of the neustonic ecosystem. For example, plastic debris may also act as a vector that distributes non-native and potentially harmful organisms in this ecosystem. Such organisms could harm the neuston either through direct predation on native species or by increased competition for food.
Although everyone agrees that we need to stop the flow of plastic into the ocean, there is considerable ongoing debate on how to minimize the considerable amounts that collect into the garbage patches, especially as it relates to the Ocean Cleanup project. The circulating currents in the garbage patch move the plastic around, creating natural ever-shifting hotspots of higher concentration. The Ocean Cleanup project relies on a huge net to passively collect plastic debris as the currents push water through it. Computational modeling helps to predict where these hotspots are located so that cleanup systems can be placed in these areas. Helm is largely critical of these net systems for their potential to harm neuston, an expected bycatch. She emphasizes the need to study and acquire a better understanding of the open ocean before manipulating it.
By using a different approach, the Ocean Voyages Institute completed in 2020 the largest single open ocean cleanup in history, recovering 103 tons of trash made up of fishing nets and consumer plastics from the Great Pacific Garbage Patch. More recently, it recovered 96 additional tons of plastic waste, again from the Great Pacific Garbage Patch. Rather than using large nets that trap bycatch, this organization minimizes neuston damage through a wide range of methods, including drones, GPS trackers attached to debris and satellite imagery, in order to efficiently recover the debris.
Meanwhile, Helm continues to unveil the mysteries of the open oceans and is a steward of high seas biodiversity. And she wants you to go to the beach, go sailing and surfing, and be an enthusiastic participant of the GO-SEA project by reporting on the neuston you see.
Author’s contact: [email protected]
