In order to understand the contribution of seaweed aquaculture to nutrients and carbon cycles in coastal environments, we measured the nutrients & carbon uptake rates of Porphyra yezoensis Ueda sampled at Nakdong-River Estuary using a chamber incubation method from November 2011 to April 2012. It was observed that the production rate of dissolved oxygen by P. yezoensis (n=30~40) was about 68.8±46.0 μmol gFW -1 h-1 and uptake rate of nitrate, phosphate and dissolved inorganic carbon (DIC) was found to be 2.5±1.8 μmol gFW -1 h-1, 0.18±0.11 μmol gFW -1 h-1 and 87.1±57.3 μmol gFW -1 h-1, respectively. There was a positive linear correlation existed between the production rate of dissolved oxygen and the consumption rates of nitrate, phosphate and DIC, respectively, suggesting that these factors may serve as good indicators of P. yezoensis photosynthesis. Further, there was a negative logarithmic relationship between fresh weight of thallus and uptake rates of nutrients and CO2, which suggested that younger specimens (0.1~0.3 g) were much more efficient at nutrients and CO2 uptake than old specimens. It means that the early culturing stage than harvesting season might have more possibilities to be developed chlorosis by high rates of nitrogen uptake. However, N & C demanding rates of Busan and Jeollabuk-do, calculated by monthly mass production and culturing area, were much higher than those of Jeollanam-do, the highest harvesting area in Korea. Chlorosis events at Jeollabuk-do recently might have developed by the reason that heavily culture in narrow area and insufficient nutrients in maximum yield season (Dec.~Jan.) due mostly to shortage of land discharge and weak water circulation. The annual DIC uptake by P. yezoensis in Nakdong-River Estuary was estimated about 5.6×103 CO2 ton, which was about 0.03% of annual carbon dioxide emission of Busan City. Taken together, we suggest more research would be helpful to gain deep insight to evaluate the roles of seaweed aquacul-ture to the coastal nutrients cycles and global carbon cycle.

As for the Jinhae bay in 2010, hypoxia under DO concentration 3 mg/L began to form from the station where thermocline formed in the early June, and hypoxia disappeared in the late October as thermocline did. DIP and DIN was much higher in the bottom water of the sea where hypoxia occurred, and pH showed its low distribution. IL, COD and AVS of the surface sediment were shown relatively high at the station which is affected by the inflow of land water from the bay Masan bay and at the station where hypoxia remains for a long time. As for benthos distribution, macrobenthos never appeared at the survey station 8 and 23 which are near the bay Hangam bay and Gohyeonseong bay and macrobenthos appeared most diversely at the survey station 11 where hypoxia did not occur. Density was also minimum at the survey station 19, 21, and 23 where hypoxia occurred, whereas density was relatively high at the survey station 11, 13 and 14 where oxygendeficient phenomenon did not occurred. Meanwhile, biomass was lowest at the survey station 23 which is affected by sewage coming from the bay Wonmun bay and shipbuilding industry, whereas biomass was highest at the survey station 14 and 11. As for benthos of the Jinhae bay, species richness and diversity was relatively high at the survey station 11, 12, 13 and 14 where hypoxia did not occur, and thus it showed relatively good benthic community structure. Like this, hypoxia appears in the bay Jinhae bay for about 5 to 6 months annually, and during that period, most of the marine environmental factors appear to be abnormal. Therefore, we need the fundamental measures to reduce hypoxia for the purpose of producing marine products continuously.