Experts are well aware that many of our oceans are running out of oxygen. Sometimes it's a consequence of pollution. Other times we can blame climate change, both man- and nature-driven. However, what is certain is that it's not good for us or the fish and crustaceans that many industries have learned to rely on. Now researchers believe they have found a way to put the oxygen back where it is needed.

A study recently published in The ISME Journal: Multidisciplinary Journal of Microbial Ecology details how researchers tested a new strategy for returning oxygen to the ocean in a Swedish fjord.

A fjord is a long, narrow, deep inlet of the sea between high cliffs, most commonly seen in places like Norway or Iceland. Their isolation from the rest of the sea makes them particularly vulnerable to the factors that cause hypoxia (loss of oxygen), but also makes them ideal places to run an experiment without fear of impacting a larger body of water.

"Our Swedish colleagues got the idea to use a pump to mix oxygen-rich surface water into the deeper parts of the water column in the fjord which was lacking oxygen," researchers Michael Forth and Alexander Treusch from the Nordic Center for Earth Evolution, Institute of Biology at the University of Southern Denmark, explained in a recent statement.

The idea is simple enough. Using specialized pumps, the researchers were able to enhance natural venting events occurring in a fjord called the Byfjord, not far from the town of Uddevalla. This brought oxygen into deeper portions of the region, which was otherwise being ignored by changing oxygen-rich water currents, much like what occurs in the Baltic Sea - a region infamous for its hypoxia.

Several decades ago, the sea was radically changed after large-scale dumping of agricultural fertilizers and sewage encouraged mass blooms of algae. When these blooms eventually died and sank to the Baltic Sea's bottom, microorganisms there began consuming oxygen at an unsustainable rate to do their job of decomposition. Unfortunately, venting along the seafloor was not enough, and the anoxic water (zero oxyegen) was trapped. Now, huge swaths of the sea are "dead zones" where fish and smaller oxygen-breathing life dare not go.

But now there's hope. In the fjord experiment, pumps were used for set periods between 2010 and 2013, but after only two months of pumping, the experts started seeing results. (Scroll to read on...)

"Already while the pumps were working we could see how some oxygen requiring bacteria returned into the deeper water of the fjord and some that don't like oxygen disappeared," Forth explained.

This was good news because past research has indicated that many microbes that thrive in anoxic conditions may actually be contributing to greenhouse gas production.

And while this may seem a little like the researchers are tampering with natural processes, they found that the fjord actually "wants" to maintain oxygen balance between all its layers.

"It seems that the fjord only needs help from time to time to restore the oxygen levels and then can maintain them for a longer period of time on its own," the team explained.

Forth and Treusch added that if fishing industries wish to see oxygen-breathing life return to the Baltic Sea, a similar strategy could be employed.

"Communities in the Baltic Sea are very similar to those in Byfjord before the fjord was aerated. So it is fair to imagine that the same change in the bacterial community will take place in the Baltic Sea if we start to pump oxygen-rich water down to the bottom waters of the Baltic Sea. This is an idea our Swedish colleagues are investigating further," they said.

Still, it remains to be seen what this could mean for ecologies as a whole, as some ecosystems may have already learned to adapt or even prosper near suffocating waters. This is why the researchers are treading very carefully as they explore this new and novel strategy for breathing life back into a sea.

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