Over the past few years, there has been an invasion of jellyfish in Japanese waters. Scientists are still unclear as to why thousands upon thousands of jellyfish descend on this area but are desperately trying to develop ways in which to predict the next outbreak.
These jellyfish spawn between China and Japan and usually reside in the “Yellow Sea and East China Sea” (2) and reports from the 1900’s show that the “Echizen Kurage” (3) or ‘Nomura Jellyfish’ only appeared in Japanese waters every forty years or so, but recently they have descended on Japan almost every year between 2002 and 2007. (1) Especially on “Iwate Prefecture, Japan” (1) and “lake Fukui prefecture, Japan” (3) with a massive outbreak on Iwate Prefecture in 2005 (1) and Japan waits with baited breath as scientists predict another invasion sometime in 2009.
Fishermen are dealing with the effects of this problem the most; everyone knows a fisherman’s main income comes from his catch. But with each Jellyfish being approximately “6ft wide and weighing up to 200Kg”(4) the weight of these monsters are damaging expensive netting used to fish. On top of this is the issue with the catch after it has been with the jellyfish. Nomura are incredibly toxic and being enclosed in the nets cause them to sting the fish making them unsellable.
The pattern as to why the Nomura appear is unknown, as is why they appear in the first place. Thankfully scientists have a few theories, however none of these are proven its merely speculation and reasoning as yet.
With Chinas recent industrial revolution there has been a boom in building projects across the country, one such project is the “three Gorges Dam” (5) the dam is fed by the Yangtze river and the Xiangxi River. The Xiangxi river is “subject to severe phosphorus pollution by the dumping of industrial waste water in the river.” (6) This in turn increases the phosphorus concentration within the dam. “Average phosphorus concentrations are 635.17mg/kg” (6) the dam is “seriously polluted by pesticides, fertilizers, and sewage from passenger boats” (7) along the rivers connecting to the dam, this increases the levels of Nitrogen in the water. Since increased levels of Nitrogen and Phosphorus are precisely the kind of environment the Nomura Jellyfish look for in a breeding ground this could be one explanation for the frequency of appearances in Japan.
Also nutrient rich run off from farms triggers a process called eutrophication, this is where the nutrients create a boom in growth of plant life in the water, reducing the water quality and ultimately killing off the fish. Which would force the jellyfish to move from their normal habitat to a more favorable hunting ground. Another problem with this is that “the fish that are dying would normally eat the larvae of the jellyfish.” (8) But if the fish are dying there will be an increase in the survival of Nomura as less of them are being eliminated as larvae. Yet another problem is if the fish are dying due to a poor oxygen supply because of eutrophication, the jellyfish are more likely to survive the poor oxygen supply as they “absorb oxygen directly through their skin.” (8)
Another theory is that, “as more ports and harbors have been built along the Chinese coast, there is an increased area for the Nomura larvae to attach to.” (8) Meaning more of the larvae survive, migrating to Japan growing into the monsters that plague the fishermen of Japan.
Finally the old adage: global warming. Scientists think that global warming is heating up the water encouraging the jellyfish’s breeding. “Acidic conditions also make breeding even more favorable for the Nomura”, (8) this means the jellyfish can thrive where others perish.
The problem with the Nomura is so bad, that the “Japanese government has created a special board to try and deal with the problem,” (8) trying to kill the jellyfish before they can do anymore harm. Also “Students in Obama Fisheries High School” (9) in Fuiki, Japan have found a way of creating a “caramel made out of sugar, starch syrup, and jellyfish powder” (9) “they also managed to extract collagen, which is beneficial for the skin.” (10)
The only major problem with all these plans to rid Japan of their gelatinous little problem is the Nomura have one final trick up their sleeve. The Nomuras’ “defense mechanism when attacked, is to send millions of eggs/sperm into the water.” (10) Which would increase the amount of the monsters threatening the waters in the long run. So for now there appears to be no real long term solution to the problem. Watch this space.
(5) http://www.zmescience.com/ecology/climate/giant-files-nomura-and-lions-mane-jellyfish-000026/ : 07/10/09
(7) http://www.china.org.cn/english/environment/226114.htm : 07/10/09