Why the Ocean needs the Desert

What do you imagine when you think of the desert? I grew up in the desert and I think of dry hot days and clear cool nights. I think of my home town where mountains and a vast sky surround us.  I think of sand and dust which permeates all crevices and openings. I think of low-lying scrub bushes and an ecosystem that, while not as diverse as the Amazon rain forest or the oceans, is certainly unique.

Source: https://www.panoramio.com/photo/96124662

What do you imagine when you think of the ocean?  I think of the ocean as the exact opposite of the desert. I have seen the ocean maybe five times in my life so my personal experiences are limited, but my first impression of the ocean was that it was overwhelmingly vast and intimidating. However, when I look beyond my own fears, I think of the ocean as a biodiverse ecosystem that is dependent on its diversity.

Courtesy: National Science Foundation

It’s hard to imagine two more different places on earth in terms of environment and animals. So what is the connection between the two, between the desert and the oceans? Dust.

Around 450 million tons of dust enter  the world’s oceans every year, and two-thirds of this dust comes from the Sahara desert. The dust from deserts can stay in the air for weeks and travel thousands of miles. The dust from the Sahara desert travels across the Atlantic ocean and deposits into the Caribbean Sea or even in the Amazon rainforest. This dust carries vital nutrients such as phosphorus, nitrogen, and iron, which are especially important to ocean ecosystems.

Visualization of aerosols produced around the world from dust to sea spray. The tan and red colors are denoting dust aerosols that are traveling.

Source: NASA/Goddard Space Flight Center

 

The importance of dust deposits in the ocean are apparent  in marine phytoplankton. Marine phytoplankton are microscopic plant-like organisms that are at the bottom of the food chain in the ocean and are a critical part for the survival of other ocean creatures. These marine phytoplankton not only serve as a food source for larger creatures in the ocean but they also consume carbon dioxide and produce oxygen. In fact, over half of the world’s oxygen is actually produced by marine phytoplankton. The rate limiting step for marine phytoplankton growth in the ocean is iron availability, which for a majority of the ocean comes from the dust produced by the great deserts of the world.

However, as fantastic as I think dust carried on the wind and contributing to the world’s ecosystems is, there can be some downsides. For example, when a lot of dust enters the ocean in   a short amount time due to dust storms in the Sahara desert, phytoplankton can create  overgrown blooms. These overgrown blooms can actually deplete the oxygen in the surrounding water and cause a dead zone in the ocean.

Despite the previously stated downside to dust, the ocean needs the desert. We, as a species, need the desert. So the next time you are thinking of the desert, think of the dust and where it’s going.

Peer edited by Kaylee Helfrich.

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