초록 ▼

∘ 쇄빙연구선 아라온호를 이용한 아문젠해 종합해양연구 (연구목표: 서남극 온난화 원인과 경향, 온난화에 따른 생태계와 생지화학순환 변화 연구) - 2013/2014 제 3차 및 2015/2016 제 4차 현장조사에서 획득한 시료와 자료 처리 및 분석, 논문화작업 연중 실시.
∘ 아문젠해역 수괴 분포와 해류 순환 패턴, 빙해역, 폴리니아, 대륙사면 등 다양한 남극 해양환경의 식물플랑크톤 종류, 분포, 생산력, 규산염, 아질산염+질산염, 암모니아, 인산염 등 기초자료 분석.
∘ 광대역 식물플랑크톤 생리활성(FIRe: Fluo

∘ 쇄빙연구선 아라온호를 이용한 아문젠해 종합해양연구 (연구목표: 서남극 온난화 원인과 경향, 온난화에 따른 생태계와 생지화학순환 변화 연구) - 2013/2014 제 3차 및 2015/2016 제 4차 현장조사에서 획득한 시료와 자료 처리 및 분석, 논문화작업 연중 실시.
∘ 아문젠해역 수괴 분포와 해류 순환 패턴, 빙해역, 폴리니아, 대륙사면 등 다양한 남극 해양환경의 식물플랑크톤 종류, 분포, 생산력, 규산염, 아질산염+질산염, 암모니아, 인산염 등 기초자료 분석.
∘ 광대역 식물플랑크톤 생리활성(FIRe: Fluorescence Induction and Relaxation), 부유 원생동물 생태적 분포 특성, 중형 동물플랑크톤 분포와 우점종 섭식율 등 자료 분석.
∘ 아문젠해 온난화에 따른 생태계 환경변화 및 반응, 탄소순환/생지화학순환 경로 연구.

(출처:보고서 초록)

Abstract ▼

IV. Results
1. Physical Oceanography in the Amundsen Sea.
In order to monitor the temporal and spatial variation of circumpolar deep water (CDW) and its effect on the rapid melting of glaciers in the Amundsen Sea, an extensive oceanographic survey was conducted on the 2016 expedition (ANA06B)

IV. Results
1. Physical Oceanography in the Amundsen Sea.
In order to monitor the temporal and spatial variation of circumpolar deep water (CDW) and its effect on the rapid melting of glaciers in the Amundsen Sea, an extensive oceanographic survey was conducted on the 2016 expedition (ANA06B). During the 2016 Amundsen Sea cruise (ANA06B) by IBRV Araon, a total of 81 CTD stations were visited, 9 moorings were successfully recovered and 6 moorings were newly deployed on the shelf troughs and near the ice shelf fronts. The thickness of CDW (defined by 0℃ isotherm) along the Dotson trough was much thinner in 2014 than in 2012 (Figure 1.2). However, the thickness of CDW layer at continental shelf break had rebounded back in 2016 and the CDW layer thickness was large compared to 2012. Two transects across the Dotson Trough show the intrusion of warm CDW, tilting toward the eastern side of the trough. A strong southward flow greater than 20cm s^-1 was measured near the bottom at eastern side of Dotson Ice Shelf from the two years mooring. At the western side of Dotson Ice Shelf, the northward flow was measured at 400 m depth.

2. Chemical Oceanography in the Amundsen Sea.
To understand biogeochemical cycles and quantify basal melting rate and its temporal variation, distributions of (1) nutrients, (2) dissolved organic carbon (DOC), (3) particulate organic carbon (POC) and nitrogen (PON), (4) noble gases and (5) dimethyl sulfide (DMS) were investigated in the Amundsen Sea. Two distinctive disappearance ratios of NO3:PO4 were observed, suggesting that Phaeocystis antarctica and diatom were dominant phytoplankton species. This result also reflected that different carbon uptake ratio by different phytoplankton taxa, which should be considered to estimate carbon flux in the Amundsen Sea. In 2013-14, high DOC concentrations (40-140 μM C) were observed between surface and 700 m, suggesting that remineralization of particulate organic matters by microbial activities was significant. In contrast, DOC concentrations observed in 2015-2016 ranged from 25-60 μM C, suggesting that marine environment was significantly different between two periods. POC and PON concentrations were high in the Amundsen polynya, and decreased with increasing depth. The results for noble gases exploited the fact that when glacier melts under high hydraulic pressure, it produces significant supersaturation (DHe~1000%) of helium in the water column. Helium supersaturation was highest near the ice shelf (> 24%) and it gradually decreased as it went far away from the ice shelf, reflecting the glacial meltwater input from the base of the ice shelf and subsequent advection and mixing by overturning circumpolar deep water (CDW). The temporal variation of the meltwater fraction appeared to be significant. Near the Doton and Getz ice shelves the meltwater fraction of 2012 was 30-40% lower than that of 2011.
These results imply that glacial meltwater influences the physical and biogeochemical processes at places as far as 300 km away from ice shelves and the rate of basal melting varies in a time scale as short as less than a year. The surface water concentrations of DMS varied from <1 to 400 nM. The highest DMS (up to 300 nM) were observed in sea ice–polynya transition zones and near the Getz ice shelf, where both the first local ice melting and high plankton productions were observed. In other regions, high DMS concentration was generally accompanied by higher chlorophyll and ΔO₂/Ar.The large spatial variability of DMS and primary productivity in the surface water of the Amundsen Sea seems to be attributed to melting conditions of sea ice, relative dominance of Phaeocystis antarctica as a DMS producer, and timing differences between bloom and subsequent DMS productions. The depth profiles of DMS and ΔO₂/Ar were consistent with the horizontal surface data, showing noticeable spatial variability. However, despite the large spatial variability, in contrast to the previous results from 2009, DMS concentrations and ΔO₂/Ar in the surface water were indistinct between between the two major domains: the sea ice zone and polynya region. The discrepancy may be associated with inter-annual variations of phytoplankton assemblages superimposed on differences in sea-ice conditions, blooming period, and spatial coverage along the vast surface area of the Amundsen Sea.

3. Characteristics of phytoplankton ecology and biological environment in the Amundsen Sea.
Two cruises were conducted in the Amundsen Sea of the Southern Ocean in austral summer (January 2014 and January-February 2016) on board R/V icebreaker ARAON. The total stations for phytoplankton physiological study were 26 and 52, respectively where seasonally sea ice covered zone, Amundsen & Pine Island polynyas, and open sea were included. During the cruise, we mainly observed maximul photosynthetic quantum efficiencies (Fv/Fm) using Fluorescence Induction and Relaxation system (FIRe) for understanding the characteristics of phytoplankton ecology and biological environment. Moreover, to demonstrate that iron limited responses of natural phytoplankton assemblages, we carried out iron assimilation experiments at four stations (open sea, outer shelf, polynya center, front of ice shelf) during more than seven days. Satellite data of daily solar irradiance were also used for analysis light regimes of study area.
Both observed and analysed data cleary showed that light availability rather than Fe controls the magnitude of massive phytoplankton bloom in this most productive system in the Southern Ocean.

4. Environmental factor controlling phytoplankton community structure in the Amundsen Sea Polynya.
The Amundsen Sea, Antarctica, is one of the vulnerable area, where increased basal melting and upwelling have occurred. Phytoplankton community dominated by Phaeocystis antarctica (Prymnesiophytes) and/or diatoms during the bloom periods, and they play different roles in the biogeochemical cycle of the Amundsen Sea polynya (ASP). To understand the distribution of phytoplankton community and the influential environmental factors in the ASP, the field surveys were conducted in January 2014 and 2016. The mean open water area of the ASP was largely extended during both austral summer of 2014 and 2016. However, the average insolation was dramatically lower in January 2016 with a lower phytoplankton biomass (chl-a) than January 2014. Phytoplankton community dominated by P. antarctica in January 2014, while diatoms, Dictyocha speculum (Chrysophytes), and P. antarctica were co-dominated in the ASP in January 2016. These results indicated that the light availability could be one of the important influential factors for phytoplankton biomass and community structure in the habitat conditions of rapidly thinning ice shelves and sea ice loss in the ASP.

5. Bioacoustics.
The DIS and GIS, two representative ice shelves in the Amundsen Sea coastal polynya, have dramatically thinned during the past two decades: the elevation have been changed 36 ±2 cm year-1and –17±6 cm year-1 from 1992 to2001 (Shepherd et al., 2004). During the last Amundsen Sea expeditions, we found that ice shelf is one of main habitats for ice krill and high density of ice krill was distributed within coastal polynya. Interestingly, two closed ice shelves showed different environmental condition, as well as ice krill density was highly different that the higher density was represented around GIS than that around DIS. In this report, we observed the meso- and macrozooplankton compositions and the vertical and horizontal distribution of sound scattering layer (SSL) around Dotson ice shelf. The SSL was classified with fish, mesozooplantkon, and macrozooplankton using dB difference method. These three groups represent the different pattern in the vertical habitat and regional location within study region.
This result could support to understand the variation of zooplankton compositions and the role of zooplankton in the Amundsen Sea marine ecosystem.

6. Microbial ecology in the Amundsen Sea
Marine microbes including bacteria and viruses are the most abundant organisms on the planet and play vital roles in the biogeochemical cycle in marine environments. Marine viruses influence the production of dissolved organ matters (DOM) and increase regeneration of nutrients by destruction of their hosts formed in particulate. Bacteria are important members of microbial foodweb which transform DOM into bacterial biomass in particulate form. Bacterial community structure is susceptible to the change of environmental conditions. To understand ecological characteristics of marine microbes in the Amundsen polynya and its vicinity, we investigated (1) spatial distribution of viruses, (2) the occurrence of lysogenized bacteria, and (3) isolation and identification of bacteria associated with phytoplankton during the ARAON cruise in January 2014. In interim results, viruses (8.1×10⁶-1.6×10⁷ viruses/ml) exceeded bacteria by ca. 14-fold in numbers. The occurrence of lysogenized bacteria was not detected in 4 out of 5 samples assessed so far, indicative of a minor contribution of lysogeny virus production to viral assemblages in the study area. Based on the 16S rRNA gene sequences, bacterial strains isolated from phytoplankton concentrates turned out to be closely related to those from plant-associated samples or those from Antarctic seas. In-depth analysis of microbial data is undergoing for better understanding the microbial interactions in the Amundsen polynya.

(출처:SUMMARY)

목차 Contents

• 표지 ... 1제 출 문 ... 2보고서 초록 ... 4요 약 문 ... 5SUMMARY ... 12CONTENTS ... 18목차 ... 19제 1 장 서 론 ... 21제 2 장 국내·외 기술개발 현황 ... 22 제 1 절 국내기술개발현황 ... 22 제 2 절 국외기술개발현황 ... 22제 3 장 연구개발수행 내용 및 결과 ... 34 제 1 절 수층 구조 특성 (김태완, 조경호, 박태욱) ... 34 제 2 절 화학환경 (정진영, 박기홍, 함도식) ... 45 제 3 절 식물플랑크톤 광합성 생리활성 (박지수) ... 70 제 4 절 식물플랑크톤 군집에 영향을 미치는 환경특성 (이영주, 양은진) ... 80 제 5 절 생물음향 (나형술) ... 88 제 6 절 미생물 생태 특성 (황청연) ... 97 제 7 절 위탁연구 수행성과 ... 106제 4 장 연구개발목표 달성도 및 대외기여도 ... 108 제 1 절 단계 및 연도별 연구목표 ... 108 제 2 절 연구개발목표 달성도 (정성적 성과) ... 108 제 3 절 주요 정성적 성과 (국제협력분야) ... 111제 5 장 연구개발결과의 활용계획 ... 114제 6 장 연구개발과정에서 수집한 해외과학기술정보 ... 115끝페이지 ... 120