14 DAY TRIAL // According to a new scientific study, it would appear that even low-scale climate fluctuations can affect the habitability of marine ecosystems to a great extent. The researchers who led the work say that the size and harshness of oceanic dead zones is directly correlated to climate.
In the investigation, researchers at the University of California in Los Angeles (UCLA) kept a close eye on how low-oxygen zones in the ocean expanded and contracted over time, correlating this with climate variations detected through other sources.
Scientists used a state-of-the-art computer model to simulate how the size of low-oxygen (hypoxic) zones – which are created by respiring bacteria – is extremely sensitive to change caused by climate oscillations.
Generally, oceanic dead zones are known to either expand or contract depending on how deep they are. This also dictates the extent of damage they will cause among native species living in the area.
Hypoxia – the lack of oxygen – is caused by algae and other similar organisms, that thrive in waters rich in nutrients such as nitrogen and phosphorus. As they develop, the algae use up all of the oxygen in the waters around them, leaving insufficient amounts for other organisms.
As such, fish and more complex species are forced to move away from the dead zones, or be killed. Dead zones develop at a variety of locations around the world, and especially at the mouth of polluted rivers that flow into seas or oceans.
The UCLA research team was led by assistant professor of atmospheric and oceanic sciences Curtis Deutsch, who also coordinated the computer simulation.
“The growth of low-oxygen regions is cause for concern because of the detrimental effects on marine populations – entire ecosystems can die off when marine life cannot escape the low-oxygen water,” the investigator explains.
“There are widespread areas of the ocean where marine life has had to flee or develop very peculiar adaptations to survive in low-oxygen conditions,” he goes on to say.
“We found there is a mechanism that connects climate and its effect on oxygen to the removal of nitrogen from the ocean. Our climate acts to change the total amount of nutrients in the ocean over the timescale of decades,” Deutsch concludes.
Details of the new work appear in the June 9 online issue of the top journal Science