Seok Jin Oh

Distribution of Water Masses and Distribution Characteristics of Dissolved Inorganic and Organic Nutrients in the Southern Part of the East Sea of Korea: Focus on the Observed Data in September, 2011

2011년 9월에 동해의 수괴 분포와 용존 무기 및 유기 영양염의 분포 특성을 파악하였다. 수온, 염분, 용존산소의 분포를통하여 연구해역의 수괴 기원은 WM(water mass)-I, WM-II, WM-III, WM-IV 등 4개의 대표적인 수괴로 구분되었으며, 그 성격은 각각 대마난류표층수, 대마난류중층수, 북한한류수, 동해고유수와 유사하였다. 용존 영양염의 경우, 용존무기 질소(DIN; dissolved inorganic nitrogen)와 용존 무기 인(DIP; dissolved inorganic phosphorus)은 WM-IV에서 가장 높았으며, WM-III, WM-II, WM-I 순으로 나타났다. 반면에 용존 유기 질소(DON; dissolved organic nitrogen)와 용존 유기 인(DOP; dissolved organic phosphorus)은 무기 영양염과 상반되는 분포를 보였다. 연구해역에서 수괴 전체에대한 DIN : DIP 비는 약 15.8로 Redfield ratio(16)에 근접한 수치를 보이고 있으나, 혼합층의 경우 5.3으로 무기질소가식물플랑크톤 성장의 제한 요인으로 작용할 수 있는 것으로 보였다. 하지만 무기 질소가 제한된 혼합층에서 DON은 용존 총 질소(DTN; dissolved total nitrogen) 중 약 70%를 구성하였다. 따라서 풍부한 DON은 동해에서 식물플랑크톤의성장을 위한 중요한 영양염 공급원으로 판단된다.Abstract − Distribution characteristics of water masses, dissolved inorganic and organic nutrients were investi-gated in the southern part of the East Sea of Korea in September, 2011. On the basis of the vertical profiles of tem-perature, salinity and dissolved oxygen, water masses in the study area were divided into 4 major groups, such asWM (water mass)-I, WM-II, WM-III, WM-IV. Their characteristics were similar to Tsushima Surface Water (TSW),Tsushima Middle Water (TMW), North Korea Cold Water (NKCW) and East Sea Proper Water (ESPW), respec-tively. In the vertical profiles of dissolved nutrients, dissolved inorganic nitrogen (DIN) and dissolved inorganicphosphorus (DIP) concentrations were highest in the WM-IV, followed by WM-III, WM-II, WM-I. On the con-trary, distribution of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) were highest inthe WM-I, followed by WM-II, WM-III, WM-IV. Although the DIN : DIP ratio in all of the water masses was sim-ilar to Redfield ratio(16), the DIN : DIP ratio in mixed layer was about 5.3, indicating that inorganic nitrogen is thelimiting factor for the growth of phytoplankton. However, the DON proportion in dissolved total nitrogen (DTN)was about 70% in the mixed layer where inorganic nitrogen is limiting factor. Thus, enriched DON may play animportant source of the nutrient for the growth of phytoplankon in the East Sea.Keywords: East Sea(동해), Water mass(수괴), Dissolved inorganic nitrogen(용존 무기 질소), Dissolved inorganicphosphorus(용존 무기 인), Dissolved organic nitrogen(용존 유기 질소), Dissolved organic phosphorus(용존 유기 인)

Dominance and Survival Strategy of Toxic Dinoflagellate Alexandrium tamarense and Alexandium catenella Under Dissolved Inorganic Nitrogen-limited Conditions

Abstract − Dominance and survival strategy of toxic dinoflagellate Alexandrium tamarense and A. catenellaunder the dissolved inorganic nitrogen (DIN) limited conditions were examined in the laboratory and fieldobservations. In Masan Bay, DIN was limiting factor for growth of phytoplankton during spring to early summerwhen Alexandrium spp. have been observed. They have a disadvantageous position compared with diatomsbecause Ks of nitrate calculated from growth kinetics experiment of A. tamarense and A. catenella was higherthan diatoms. However, A. tamarense and A. catenella were able to grow using dissolved organic nitrogen (DON)compounds such as urea and amino acids as well as DIN. Therefore, DON utilization of A. tamarense, A.catenella might contribute to not only their population growth but also dominance and interspecific competitionin the DIN-limited conditions in Masan Bay.Keywords: Alexandrium tamarense, Alexandrium catenella, dissolved inorganic nitrogen (DIN; 용존무기질소),dissolved organic nitrogen (DON; 용존유기질소 )

Effects of Temperature and Salinity on the Growth of Marine Benthic Microalgae for Phytoremediation

Abstract − To improve sediment quality in eutrophic coastal areas using benthic microalgae, we examined theeffects of temperature and salinity on the growth of benthic microalgae Achnanthes sp., Amphora sp., Naviculasp. and Nitzschia sp. isolated from Sujeong Bay, Korea, using batch cultures. The maximum growth rates wereobtained under the combined temperature and salinity conditions of 25 o C and 25 psu for Achnanthes sp. (0.60/day), 15 o C and 25 psu for Amphora sp. (0.56 /day), 20 and 30 psu for Navicula sp. (0.53 /day), 20 o C and25 psu for Nitzschia sp. (0.48 /day). Considering these results of temperature and salinity conditions requiredfor optimum growth (≥ 70% of maximum specific growth rate), Amphora sp. Navicula sp. and Nitzschia sp.were characterized as eurythermal and euryhaline species, while Achnanthes sp., which exhibited extremely lowsurvival at low temperature. In conclusion, Amphora sp., Navicula sp. and Nitzschia sp. may be useful speciesfor phytoremediation, to control eutrophication and hypoxic water and thus improve environmental conditionsof polluted coastal areas.Keywords: Benthic microalgae(저서미세조류), Achnanthes sp., Amphora sp., Navicula sp., Nitzschia sp.,Growth(성장), Temperature(수온), Salinity(염분), Phytoremediation(식물환경복원 )

Effects of Irradiance on the Growth of the Toxic Dinoflagellates Alexandrium tamarense and Alexandrium catenella

Abstract The effects of irradiance on the growth of toxic dinoflagellates Alexandrium tamarense (Masan Bay strain) and Alexandrium catenella (Jinhae Bay strain) were investigated in the laboratory. At 15℃ and 30 psu for A. tamarense and 25℃and 30 psu for A. catenella , the irradiance-growth curve showed the maximum growth rate (μ max ) of 0.31 day -1 with half-saturation photon flux density (PFD) (K I ) of 44.53 μmol m -2 s -1 , and a compensation PFD (I c ) was 20.67 μmol m -2 s -1 for A. tamarense , and μ max of 0.38 day -1 with K I of 59.53 μmol m -2 s -1 , and I c was 40.80 μmol m -2 s -1 for A. catenella . The I c equated to a depth of 8~9 m from March to June for A. tamarense and 6~7 m from March to June for A. catenella . These responses suggested that irradiance at the depth near the middle layer in Masan Bay would provide favorable conditions fortwo species. Key words : Alexandrium tamarense , Alexandrium catenella , Irradiance, Growth, Masan Bay 1. 서 론 1) 하천으로부터 대량으로 유입되는 점토입자와 같은 육원성기원 물질은 연안해역에서 강한 조석현상으로 인해 오랫동안 재부유하며, 영양염과 식물플랑크톤 등을 흡착 침강시켜 일차생산자의 대량성장을 억제시키는 역할을 한다. 또한 연안해역에서 부유물질의 농도 증가는 빛의 공급을 제한시켜, 식물플랑크톤의 현존량 및 성장속도를 조절하는 주요요인으로 작용한다(Cloern, 1987). 우리나라 연안해역에서도 대형 임해단지조성 및 육상기원의 현탁물 유입으로 인해 다량의 부유물질이 해양으로 유입되고 있어, 하천과 하구역 같은 곳은 소산계수가 2이상의 매우 높은 값을 나타내며, 영양염의 제한보다 부유물질에 따른 조도의 제한이 식물플랑크톤의 성장을 억제하기도 한다 (Yoon, 2000; Oh 등, 2008). 반대로, 일본 Ariake 해는 부유물질 농도의 감소에 따른 투명도의 증가로 퇴적물에 있는 규조류의 휴면기 세포(resting spore)가 발아되어 규조류에 의한 적조 발생 빈도가 증가되었다는 보고도 있다(Kiyomoto 등, 2008).

Effects of Substrate Size on the Growth of 4 Microphytobenthos Species (Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp.)

The effects of substrate size on the growth of microphytobenthos Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp. were examined using glass beads in order for phytoremediation in the benthic layer of coastal waters. The glass beads used in this study were 0.09~0.15 mm (G.B 1), 0.25~0.50 mm (G.B 2), 0.75~1.00 mm (G.B 3) and 1.25~1.65 mm (G.B 4). No addition of glass bead used as control. The specific growth rate and maximum cell density of four microphytobenthos species were increasing with decreasing size of glass beads. Moreover, the control experiment without added attachment substrates showed the lowest specific growth rate and maximum cell density. Therefore, the suitable attachment substrates for mass culture of microphytobenthos seems to be important in order for phytoremediation using microphytobenthos.