Dust, microscopic pieces of anything from skin tissue to microplastics, are carried by the wind and land on surfaces like a table, an Arctic fox’s fur, or the ocean’s surface. Humans may view dust as an irritation to be removed or pollution to avoid inhaling, but dust really benefits the world’s aquatic ecosystems.
Toby Westberry, an oceanographer at Oregon State University (OSU), has recently conducted a new study that examines dust’s role in maintaining marine life and controlling atmospheric carbon dioxide levels.
In the journal Science, the paper Atmospheric Nutrition of global ocean ecosystems was released.
According to a press release from OSU, scientists have long recognized that phytoplankton, plant-like organisms that live in the upper water and form the base of the marine food web, depend on dust from the land for vital nutrients.
The authors of the study concluded that whereas most essential nutrients for phytoplankton development in the sunlit surface layer are delivered through physical movement from deep waters, some nutrients are also provided via atmospheric deposition of desert dust.
It has been challenging for scientists to assess how much marine organisms depend on dust from soil and other sources carried to them by the wind and that also affects the climate of the globe.
In the news release, Westberry stated that this is actually the first time it has been demonstrated, using the contemporary observational record and at the global level, that the nutrients delivered by dust being deposited on the ocean are causing a response in the surface ocean life.
Through photosynthesis, phytoplankton contributes significantly to the carbon cycle by converting atmospheric carbon dioxide that dissolves in surface ocean waters into organic matter. Some of this organic material gets deposited at the planet’s largest carbon sink, the ocean, where it sinks to the bottom and is no longer able to contribute to global warming.
For the study, Westberry and other researchers calculated that the regional levels of dust are close to 20 to 40 percent of the worldwide annual amount of carbon absorbed by the ocean, which is 4.5 percent.
That is significant because, according to Westberry, it provides a route for carbon dioxide to travel from the atmosphere to the deep ocean. One of the main regulators of atmospheric carbon dioxide, a major contributor to both global warming and climate change, is the biological pump.
The process of upwelling, which brings the majority of essential nutrients for phytoplankton development to the surface of the ocean, also brings some nutrients from air dust.
Historically, major occurrences like volcanic eruptions, wildfires, and violent dust storms have been recognized as atmospheric input sources of nutrients into marine ecosystems.
However, for the latest study, the researchers broadened their investigation to cover phytoplankton reactions all across the world.
The study team examined how the addition of dust affected the ocean’s color using satellite data. Greener seas often represent regions with numerous and robust phytoplankton communities, while bluer waters denote regions with fewer and frequently malnourished populations.
It is challenging to estimate the amount of dust deposited into the ocean since a large portion of the deposition takes place during rainstorms when satellites cannot see the dust. That is why, according to Lorraine Remer, a research professor at the Goddard Earth Sciences Technology and Research Center II, a consortium led by UMBC, we resorted to [observations of] a [NASA global] model.
The research team discovered that the location affects how phytoplankton reacts to dust deposition. For instance, in low-latitude ocean regions, dust is typically seen as favorable to phytoplankton health but not abundance. But in waters at higher altitudes, the presence of dust frequently enhances the well-being and abundance of phytoplankton. This is because there are different interactions between phytoplankton and the marine organisms that eat them.
Due to the intimate association between phytoplankton development and predation in lower altitude marine habitats, which are more stable, phytoplankton that are made healthier and more plentiful by the presence of dust are swiftly eaten.
Higher elevations, however, have constantly shifting climatic circumstances that provide a weaker connection between phytoplankton and their predators, resulting in thriving and numerous phytoplankton populations.
According to Westberry, who was quoted by Earth.com, the latest investigation shows quantifiable ocean biological reactions to a wide dynamic range in air inputs. This connection between the atmosphere and oceans will likely shift as the globe continues to warm.