eco otaku

Late last year, a 10 tonne Japanese fishing trawler was hauling in a heavy catch when the weight of the net forced the boat to capsize, throwing the crew of three into the waters off Chiba, Japan. The crew were later rescued. This was not a giant octopus, it was rather a large haul of giant Nomura Jellyfish.

Nomura Jelly fish are a very large jellyfish that can grow to as large as 200 kilograms with a diametre of 2 metres. These large floating jellies have been increasing to large numbers in Japan to an estimated number of 500 million. According to an article in The Japan Times by Micheal Casey, a journalist for the Associated Press, comments that these large blobs made a mass appearance around once every 40 years, but as of 2002 that have been present in large numbers every year.

In a country where seafood is of the most importance to the culture, this issue has large implications for the society in Japan. Nomura Jellyfish are in such great numbers that they are destroying fish catches by overwhelming numbers. They are also stinging the captured fish, which can severely decrease the value of the fish price at market.

While a number of factors could be to blame, including overfishing of predatory fish that prey on the Jellyfish or changes to the habitat where Jellyfish breed, the change in climate could be a major influence.

Scientists from Hiroshima University have been studying the unusual movements of the Nomura Jellyfish which usually inhabits warmer waters off china. It has been established that the warming of the water around Japan from climate change has played a significant role in the Jellyfish invasion with the growth of perfect feeding grounds for phytoplankton. Much in the same way that the change in climate could benefit the dispersal of malaria via mosquitoes, these Jellyfish are moving into the Japanese waters on mass as the water temperature is warming, becoming more suitable as Jellyfish habitat.

This phenomenon is not limited to Japan, with many nations experiencing significant increases in Jellyfish. According to a paper from the journal of Fisheries Oceanography, “Evidence for a substantial increase in gelatinous plankton in the Bering Sea, with possible links to climate change”, indicates that the warming of the oceans from climate change correlates with the increase in numbers. Although, more recently, they have found numbers to have decreased which could point to other contributing factors. Climate conditions for increasing Jellyfish numbers is also reflected in the findings of Jenny Purcell, a leading scientist on Jellyfish. She claims that

There keeps coming up again and again examples of jellyfish populations being high when it’s warmer.

saying further that…

It’s hard to deny that there is an effect from warming.

Its clear that the climate change is already changing the worlds ecosystems. Even small changes in temperatures are proving lethal for our oceans, and amplifying problems that seemed minor in the past. The changing conditions to the oceans could see many species that inhabit the oceans disappear and other take over the ocean. Which would you prefer for dinner, fish or Jellyfish?

Sources;

http://search.japantimes.co.jp/cgi-bin/nn20091118f1.html

http://www.pmel.noaa.gov/np/pages/inter-agency/brodeur_jellyfish.pdf

http://www.pmel.noaa.gov/foci/publications/2008/brodS668.pdf