James Harvey

Environmental Seminars

Instructor Khan-Bureau

5/9/12

Dr. Jang K. Kim

            Dr. Jang K. Kim is an assistant research professor the University of Connecticut’s department of marine sciences. He received his Master’s degree in Marine Botany and PH.D in the same subject at the University of Connecticut and he is involved in several research projects involving nutrient bio extraction, is involved in academia, industry, research projects, and he has received several federal grants and published a number of papers.

            Kim spoke to us about seaweed aquaculture in the Long Island Sound and stated that captured fish has maxed out in the 1980s and at the same time, the aquaculture started to grow rapidly and has become more than 1/3 of the production of fish. As for seaweed it has also increased by 8% per year since 1970. We can use seaweed for food, feed, fertilizer, medicine, cosmetics, textile, paper, leather, major sources of phycocolloids (alginates, carrageenans, and agars, usually in ice cream and chocolate milk according to Kim), and biofuels. However, Kim then stated that humans have altered the global nitrogen cycle. We have created problems and nitrogen is in land, water, and air. Fortunately, research has been done to reduce a significant amount of nitrogen in the water and plants aren’t the only sources of nitrogen as there are other non-point sources like crops and livestock; when it rains, there’s also runoff.

            In addition, dissolved oxygen was in the Long Island Sound bottom waters in 2012 of August 14-16. Hypoxia occurred where the water has too many nutrients and phytoplankton consume those nutrients and in turn the oxygen. According to Daniel C. Esty in the 2012 Long Island Sound Hypoxia review, “hypoxia exists when DO drops below a concentration of 3 milligrams per liter (mg/L), although ongoing national research suggests that there may be adverse effects to organisms even above this level, depending upon the length of exposure.” Kim stated that this usually occurs once every year during the warmer periods. Fortunately, there’s a method of preventing this and Kim stated that it is nutrient bioextraction, which is the removal of nutrients from an aquatic ecosystem through the harvest of enhanced biological production (aquaculture of seaweed and/or shellfish). According to Kim, It is done by basically growing seaweed in the water using aquaculture techniques and as they grow, they take the nutrients from the water to reduce the amount of them and improve the water quality.

            To continue on, Kim stated that there are different sites and in a site in the Bronx, it has a higher concentration of nitrogen and phosphorus than the lower sites, which raise in the winter seasons. There are also two different species of seaweed that are grown. One is called gracilaria tikvahiae and is a native species.  It has a high value of $645 million annually and it likes to grow in the summer months when the temperature is above 15 degrees. According to Kim, the Gracilaria likes to grow in the warmer months and doesn’t grow equally everywhere as it seemed to grow higher in the Bronx site. Its productivity in the Bronx is 365g per month per 100 meter longline in July while in Long Island Sound it’s 73 g per month, which is pretty good for the Bronx compared to the Long Island Sound. However, as seen above, nitrogen removal is higher in the Bronx site than the Long Island Sound due to the pollution of the area.

            The second species is Saccharina or sugar kelp/brown seaweed. Kim informed us that it is a winter crop and its growing season is Nov – May below 15 degrees Celsius or 60 degrees Celsius. It is the most widely cultivated species and it has significant potential for the cultured sea vegetable industry in Long Island Sound and the northeast. Kim also mentioned that has two life stages and one is sporophyte, which reproduces. When these spores are released, they are put onto seed strings and they develop into male and female plants and go into a gametophyte stage and they are pretty microscopic. They go through maturity and fertilization and then develop. When the plant reaches the size of a pin head, it is then put into the seaweed farm and after five months, they grow significantly.

            To add on, the Saccharina’s productivity is quite impressive as it about 1,752 kg per meter with an estimate of about 120 metric tons, which is massive. Research was also conducted in three different sights in the Bronx, Western Long Island Sound, and Central Long Island Sound. According to Kim productivity is equal between the Bronx and Western LIS, but in the Bronx site, there is a higher nitrogen concentration that the plants can use for their tissues while the other two sites are suffering from nitrogen depletion. There are also other methods of nutrient bioextraction that appear to be more effective as mussels have a productivity of about 217kg and oysters 331kg, while sugar kelp is 180 kg in Nov-May and the Gracilaria is 140kg in July-Oct. The numbers for the kelp and Gracilaria appear to be quite low but could they be comparable if they were combined? This especially needs to be taken into account from the Nitrogen Trading program in CT that gives a town a goal to achieve for an amount of nitrogen they can remove in each year. If they reach or overachieve their goal, they get a nitrogen credit, but if they can’t, then they have to pay to have the nitrogen removed. According to the DEEP in the Nitrogen Control Program for Long Island Sound, “completed plans for nitrogen control that identifies the maximum amount, or the Total Maximum Daily Load (TMDL), of nitrogen that can be discharged to Long Island Sound without significantly impairing the health of the Sound.”

            To conclude, seaweed aquaculture has become a top research method in the EPA and it is even used for other methods. Liquid seaweed has even been used as a fertilizer and Kim stated that people are even using kelp to brew a kelp beer and in the fall, they are even thinking about putting it on a product line.  It also is being used for cosmetics. With the versatility of seaweed and how it is used for numerous things, I found it surprising that it’d be a top method because it appeared that from its versatility, it wouldn’t be as great as others. However, with the fact that kelp can make over $4,000 each year in nitrogen extraction, according to Kim, that itself prove its sufficiency.

Sources

Daniel C. Esty (2012). Long Island Sound Hypoxia Review. Retrieved from http://www.ct.gov/deep/lib/deep/water/lis_water_quality/hypoxia/2012_season_review_final_web.pdf

DEEP. Nitrogen Control Program for Long Island Sound. Retrieved from http://www.ct.gov/deep/cwp/view.asp?a=2719&q=325572&deepNav_GID=1635%20