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09/25/2016 Interview > Faculty Important News

Title

Protecting Our Water Sources

Explaining the cause of unusual red tides in Korean waters

인터넷한양

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http://www.hanyang.ac.kr/surl/iuCB

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Professor Han Myung-soo of the Department of Life Science is a researcher whose interests lie in algal phenomena such as red and green tides. Recently, he revealed the reason behind the unusual red tide caused by a sudden growth of planktons, frequenting the Korean waters in his paper titled “A mutualistic interaction between the bacterium Pseudomonas asplenii and the harmful algal species Chattonella marina (Raphidophyceae),” which was selected as the paper of the week.

You may have heard that one of the side effects of global warming is red and green tides, or ‘algal bloom’ where algae suddenly flourish and cover vast areas of waters. The rise in ocean temperature, as well as in lakes, rivers and other types of freshwater causes the algae to flourish, threatening  organisms as well as to people who equate  freshwater as drinking water. Water pollution is another cause, with eutrophication creating excellent conditions for these photosynthetic unicellulates. 

▲Cochlodinium causes red tides, which have a detrimental effect on water biology as well as humans.
Photos courtesy of Shinhanilbo and CIMT

Not only does red and green tides affect physical health biology and people, the perishing of fish in fish farms impacts fisherman economically, adding to the fact that this is aesthetically displeasing. The unicellular algae have evolved to protect themselves from possible predators, by producing harmful toxins that may cause diarrhea, amnesia, or even paralysis. "There have actually been cases where people have died, tens at a time due to drinking water or consuming shellfish affected by harmful algae. The fact that these toxins cannot be destroyed in boiling water makes it an even bigger danger," mentioned Han.

However, the rise in water temperature and eutrophication alone cannot explain the cause of harmful algae suddenly 'blooming' in certain conditions. "Yes, these algae being plants, they thrive in warm, nutritious conditions with lots of light. It is usual for red and green tides to last for one or two weeks. However, in the last couple of decades, we have seen a single type of algae dominate all three adjacent waters of the Korean peninsula from late August into the end of November. This is the most unusual phenomenon, and have puzzled many scientists," commented Han. Thus, Han and his lab set up a theory that a third biological factor must be contributing to the abnormal blooming of algae.

Focusing on Cochlodinium, the algae that are affecting the Korean waters the most, Han looked into bacteria that may be interacting with the algae. “We came to recognize that a type of bacteria called pseudomonas asplenii may be the biological factor we were looking for. It has already been revealed by other researchers that this bacteria produces minerals, that allows algae to flourish even in adverse conditions,” Han said. He and his lab gathered field samples from nearby waters twice a week, monitoring how the algae was blooming, as well as the activity of the bacteria. “It was a long-term project. The monitoring process spans months, not to mention that algal bloom didn’t always occur where we wanted it to. If we couldn’t get field samples, we would have to wait until the next red tide, which could occur the next year for all we know,” Han explained.

Han applied the field of molecular biology to his research. “We used something called ‘next generation sequencing,’ which allowed us to conduct a quantitative and qualitative analysis on the bacteria. We found out that the bacteria grew in number and thrived at the same rate and time as the algae.” Now that a new mechanism has been revealed, this new development may lead to forecasting technologies that may prevent damages caused by algal tides. He added, “We think that there may be mutualistic interaction and coexistence between the algae and bacteria, but we haven’t figured out exactly what the algae provides for the bacteria. Our next goal is to reveal that part, as well as studying the cause of green tides which occur in fresh water. I’m glad that we have experts in diverse fields to conduct combined researches between fields.”

▲Han takes pride in his work, saying that the ability to collaborate with different fields is the strength and tradition of his lab.

Nam-Hyung Kim           lucipucy@hanyang.ac.kr

Photo by Younsoo Kim

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