Findings from a new study funded by the National Science Foundation point to a clear link between the emergence of marine dead zones in the North Pacific and past abrupt large-scale ocean warming events. Apparently, two major warming events that happened at the end of ice age thousands of years ago induced hypoxia and low-oxygen levels in water.
The researchers found out that the major ocean warming events that happened about 14,700 years and 11,500 years ago led to the sudden rise in the number of planktons in the ocean.
These diatoms thrive in warm water and tend to sink at the bottom of the sea. Researchers found out that planktons need nutrients to grow too. However, since they are found in the bottom of the ocean and most nutrients can be found there, it could lead to a sudden population explosion leading to lower oxygen levels in the water and eventually hypoxia.
"Our study reveals a strong link between ocean warming, loss of oxygen and an ecological shift to favor diatom production," said study researcher Summer Praetorius of the Carnegie Institution for Science.
"During each warming event, the transition to hypoxia occurred abruptly and persisted for about 1,000 years, suggesting a feedback that sustained or amplified hypoxia."
The researchers point out that many people might assume that the effects of climate change will be 'gradual and predictable'. However, the results of the study shows that 'ecological consequences' of global warming can greatly impact oceans and marine life.
Recently, abnormal warming in the Northeastern Pacific Ocean and Bering Sea occurred and if continues warming will occur; this might pose a risk of hypoxia in the waters that might affect marine life.
Aside from 'dead zones' see in North Pacific, algal bloom in the area was also recorded this year. A certain species of diatoms were observed and scientists believe that if this situation will continue, people should expect the same situation to happen again in the future. This might not happen in the next few years, but in the next decades or centuries.
The study was published in the journal Nature.