A filamentous green alga Cladophora vadorum (Areschoug) Kützing, bloomed at Shangrok Beach, Buan, Republic of Korea, in September 2015. This alga is currently distributed worldwide. Concentrations of total nitrogen (TN), total phosphorus (TP), dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphorus (DIP) were analyzed in the bloom area and compared to those of other areas in the vicinity. DIN and DIP concentrations were similar to those of other areas. However, TN and TP were as much as six and ten times higher than in other areas, respectively. As in other Cladophora species, the bloom of C. vadorum at Shangrok Beach in 2015 appears to have depended on the TP concentration in the seawater. This suggests that blooms in the area can be controlled by reducing TP.Key words: Bloom, Cladophora vadorum, Total Phosphorus, Total Nitrogen This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

To determine whether the seaweed Saccharina japonica can effectively utilize dissolved nutrients from Sebastes schlegeli fish cultures, a laboratory experiment was conducted in a static system for 7 days at ESFRI, NFRDI in Korea. The experiment included an S. schlegeli monoculture system and an S. schlegeli-S. japonica IMTA system. Saccharina schlegeli density (415±24 g; mean±SE) remained the same in all treatments, whereas seaweed density varied across treatments of 0, 0.5, 1, 2, and 3 kg (control and T1-T4, respectively). During the experiment, nutrient (NH4 + and PO4 3-) concentrations were measured at 24-h intervals. NH4 + concentration of the control group increased from 0.117±0.021 mg/L at the start of experiment to 5.836±0.904 mg/L at the end of experiment. NH4 + concentrations of each treatment were 3.004±0.040, 2.086±0.133, 1.642±0.121 and 0.775±0.007 mg/L in T1, T2, T3, and T4, respectively, at the end of experiment. The concentration of PO4 3exhibited a similar trend to NH4 + concentration. NH4 + and PO4 3concentrations significantly decreased with increased S. japonica thallus density each day (P<0.05). The nutrient removal efficiency (NRE) and nutrient uptake rate (NUR) showed different relationships with changes in thallus density; NRE increased but NUR decreased as thallus density increased. Based on measured concentrations of NH4 + and S. japonica weight, regression analysis defined the relationship between as an exponential function, Y = 3.8165e -0.505X (R 2 = 0.9552). Our results demonstrated that S. japonica can function as an efficient component in IMTA with environmental and potentially economic benefits for fish hatcheries.