Oregon
The dead zone off the coast of Oregon made its first appearance in the summer of 2002. It was discovered by the large numbers of dying bottom fish and crabs. Extremely low levels of oxygen had been found in an area of water where it was impossible for marine life to survive. Since then, the dead zone kept forming every Summer. Scientists that have been studying the area claim that they seem to be linked to a persistent northerly wind that is present every summer. The hypoxic zone still holds many mysteries in regards to how it was formed and not much information is gathered, only expanding evidence and statistics.
The Dalles Chronicle.
(2013). Ocean dead zone a mystery in Oregon.Available: http://www.thedalleschronicle.com/news/2013/aug/31/ocean-dead-zone-mystery-oregon/. Last accessed 24th March 2014.
The Dalles Chronicle.
(2013). Ocean dead zone a mystery in Oregon.Available: http://www.thedalleschronicle.com/news/2013/aug/31/ocean-dead-zone-mystery-oregon/. Last accessed 24th March 2014.
http://www.youtube.com/watch?v=IalyBLmJbtQ
In this video, Jack Barth, who is an Oregon State University Oceanographer measures the temperature, salinity and dissolved oxygen in the waters off the coast of Oregon analysing how dead zones are formed and the causes. It also shows the future investigation plans and technology involved.
Causes
The causes of the dead zone off the coast of Oregon are still being investigated. Usually, hypoxic zones are caused heavy run-off or agriculture, because of the huge amounts of phosphorus are deposited from fertilizers. However, the Oregon dead zone was not influenced by any of these factors, so it was included that it was caused by a natural phenomenon. Natural shifting cycles and some element of human element were the most likely theories. Climate change is likely responsible for the formation, because the dead zone occurs every season and climate change is a seasonal change.
The influence of climate change causes coastal upwelling. When summer arrives, it brings along strong north winds which synergizes with the Earth's rotation in order to push the warmer surface water offshore and becomes replaced by the cold deep water off the continental shelf. Algal bloom becomes amplified by this process, because the cold water is rich in nutrients, which fuel it more and is also less in oxygen. The damage this causes usually becomes restored when the north winds switch to the South, combining the oxygen-rich water with the cold-upwelled water, creating a life-nourishing ecosystem that is rich with oxygen. However, this pattern has been disrupted by an unknown cause, making periods of South Winds shorter and weaker in recent years, gradually increasing the size of the dead zone every year.Environment News Service.
(2009). Oregon Dead Zone Blamed On Climate Change. Available: http://www.ens-newswire.com/ens/oct2009/2009-10-08-092.asp. Last accessed 23 March 2014.
The influence of climate change causes coastal upwelling. When summer arrives, it brings along strong north winds which synergizes with the Earth's rotation in order to push the warmer surface water offshore and becomes replaced by the cold deep water off the continental shelf. Algal bloom becomes amplified by this process, because the cold water is rich in nutrients, which fuel it more and is also less in oxygen. The damage this causes usually becomes restored when the north winds switch to the South, combining the oxygen-rich water with the cold-upwelled water, creating a life-nourishing ecosystem that is rich with oxygen. However, this pattern has been disrupted by an unknown cause, making periods of South Winds shorter and weaker in recent years, gradually increasing the size of the dead zone every year.Environment News Service.
(2009). Oregon Dead Zone Blamed On Climate Change. Available: http://www.ens-newswire.com/ens/oct2009/2009-10-08-092.asp. Last accessed 23 March 2014.
Figure 12:
This image is a map depicting a dead zone off the coast of Oregon that was recorded during October 2009 from the Los Angeles Times. From the figure, we can interpret that the dead zone is over 200 kilometers in length and approximately 40 kilometers in width. It shows the near anoxic zone in the Pacific Ocean in the northwest. It provides information about the level of oxygen in the affected area, the majority of it being low-oxygen conditions and the minority being extremely-low oxygen. The hypoxic area is an important issue regarding to the huge risks and hazards it has towards the marine life that live there. As of recent discoveries, only areas of the deeper water are too oxygen depleted to support most ocean life. The Los Angeles Times indicates that these low oxygen zones that had lurked well offshore before are starting to expand upwards, killing more fish and marine life along the Pacific Northwest.
Charlie Petit. (2009). Watery woes. Is it Climate Change? Nat'l Geographic on the Med's mucus; LA Times and the growing Oregon-Washington Dead Zone. Available: https://ksj.mit.edu/tracker/2009/10/watery-woes-it-climate-change-natl-geogr. Last accessed 13th March 2014.
This image is a map depicting a dead zone off the coast of Oregon that was recorded during October 2009 from the Los Angeles Times. From the figure, we can interpret that the dead zone is over 200 kilometers in length and approximately 40 kilometers in width. It shows the near anoxic zone in the Pacific Ocean in the northwest. It provides information about the level of oxygen in the affected area, the majority of it being low-oxygen conditions and the minority being extremely-low oxygen. The hypoxic area is an important issue regarding to the huge risks and hazards it has towards the marine life that live there. As of recent discoveries, only areas of the deeper water are too oxygen depleted to support most ocean life. The Los Angeles Times indicates that these low oxygen zones that had lurked well offshore before are starting to expand upwards, killing more fish and marine life along the Pacific Northwest.
Charlie Petit. (2009). Watery woes. Is it Climate Change? Nat'l Geographic on the Med's mucus; LA Times and the growing Oregon-Washington Dead Zone. Available: https://ksj.mit.edu/tracker/2009/10/watery-woes-it-climate-change-natl-geogr. Last accessed 13th March 2014.
Effects
The dead zone off the coast of Oregon mainly damages its seafood industry. Every year, when the south winds return and bring back oxygen rich waters and nourish the ecosystem, the seafood industry flourishes. However, the industry became severely damaged when the north winds occurred more frequently than the south winds, creating an expanding dead zone that decimated the populations of fish, crabs and shrimps. There have been several discoveries of large numbers of dead crabs on the shores of Oregon and recent research have also proved that there have been reproductive problems for fish, creating lack of spawning and low egg counts. The dead zone is a significant threat to Oregon's economical health.Robert Simmon. (2012). What Causes Ocean Dead Zones?. Available: http://www.scientificamerican.com/article/ocean-dead-zones/. Last accessed 23th March 2014.