• Ocean and Polar Research
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• 제44권1호
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• pp.69-82
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• 2022

The Ross Sea, Antarctica plays an important role in the formation of Antarctic Bottom Water (AABW) which is the densest water mass in global thermohaline circulation. Of the AABW, 25% is formed in the Ross Sea, and sea ice formation at the polynya (ice-free area) developed in front of ice shelves of the Ross Sea is considered as a pivotal mechanism for AABW production. For this reason, monitoring the Ross Sea variations is very important to understand changes of global thermohaline circulation influenced by climate change. In addition, the Ross Sea is also regarded as a natural laboratory in investigating ice-ocean interactions owing to the development of the polynya. In this article, I introduce characteristics of the Ross Sea described in previous observational studies, and investigate variations that have occurred in the Ross Sea in the past and those taking place in the present. Furthermore, based on these observational results, I outline variations or changes that can be anticipated in the Ross Sea in the future, and make an appeal to researchers regarding the importance and necessity of continuous observations in the Ross Sea.

• 수산해양기술연구
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• 제59권2호
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• pp.117-124
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• 2023

This study used hydroacoustic method to identify the vertical and horizontal distribution of Antarctic silverfish in the Ross Sea, Antarctica. In February and December 2018, Antarctic silverfish was detected up to 250 meters, and was mainly distributed in water depths of 20 to 30 meters. The horizontal distribution of Antarctic silverfish was mostly undetected in February, and December showed a relatively stronger distribution than that of February. Antarctic silverfish is characterized by their distribution near sea ice.

• 한국해양생명과학회지
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• 제4권1호
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• pp.22-28
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• 2019

The bacterial diversity of an Antarctic hard coral, Errina fissurata, was examined by isolating bacterial colonies from crushed coral tissue and by sequencing their 16S rRNA gene. From the analyzed results, the bacteria were classified as Actinobacteria (56%), Firmicutes (35%) and Proteobacteria (9%). The thirty-four isolates were cultured in liquid media at different temperatures and their growth was assessed over time. The majority of the isolates displayed their highest growth rate at 25℃ during the first three days of cultivation, even though the coral was from a cold environment. Nevertheless, strains showing their highest growth rate at low temperatures (15℃ and 4℃) were also found. This study reports the composition of an Antarctic hard coral-associated culturable bacterial community and their growth behavior at different temperatures.

• Ocean and Polar Research
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• 제27권3호
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• pp.277-288
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• 2005

Spatial distribution and vertical structures of water masses around the Antarctic continental margin are described using synthesized hydrographic data. Antarctic Surface Water (AASW) over the shelf regime is distinguished from underlying other water masses by the cut-off salinity, varying from approximately 34.35 to 34.45 around Antarctica. Shelf water, characterized by salinity greater than the cut-off salinity and potential temperature less than $-17^{\circ}C$, is observed on the Ross Sea, off George V Land, off Wilkes Land, the Amery Basin, and the Weddell Sea, but in some shelves AASW occupies the entire shelf. Lower Circumpolar Deep Water is present everywhere around the Antarctic oceanic regime and in some places it mixes with Shelf Water, producing Antarctic Slope Front Water (ASFW). ASFW, characterized by potential temperature less than about $0^{\circ}C$ and greater than $-17^{\circ}C$, and salinity greater than the cut-off salinity, is found everywhere around Antarctica except in the Bellingshausen-Amundsen sector. The presence of different water masses over the Antarctic shelves and shelf edges produces mainly three types of water mass stratifications: no significant meridional property gradient in the Bellingshausen and Amundsen Seas, single property gradient where ASFW presents, and a V-shaped front where Shelf Water exists.

• 한국미생물·생명공학회지
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• 제46권3호
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• pp.234-243
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• 2018

남극해에는 산업적으로 유용한 신규 효소촉매를 생산하는 미생물들이 들어 있다. 우리는 로스해(Ross Sea)로부터 분리한 여러 저온성 박테리아를 조사하였으며, 그 중에서 지방분해 능력이 뛰어난 Croceibacter atlanticus (No. 40-F12)를 찾았다. Shotgun 클로닝 방법으로 리파아제 유전자(lipCA)를 찾았으며 Escherichia coli 균에서 LipCA 효소를 발현하였다. Spain Arreo metagenome alpha/beta hydrolase를 기준으로 LipCA 상동구조모델을 만들어서 분석한 결과, ${\alpha}/{\beta}$ hydrolase fold, Gly-X-Ser-X-Gly motif, 그리고 lid 구조를 갖고 있기 때문에 전형적인 리파아제 효소임이 밝혀졌다. Ammonium sulfate 침전법과 겔여과 크로마토그래피를 통해서 세포추출액으로부터 LipCA 효소를 순수하게 분리한 후, 최적 온도, pH, 안정성, 기질특이성, 유기용매 안정성 등의 효소특성을 규명하였다. LipCA를 cross-linked enzyme aggregate (CLEA) 방법으로 고정화하고 효소특성을 조사, 비교하였다. 고정화를 통해 온도, pH, 유기용매에 대한 안정성이 증가하였고 기질특이성의 변화는 관찰되지 않았다. $LipCA^{CLEA}$는 원심분리 방법으로 쉽게 회수되었고 4번의 재사용 후에 40% 이상의 활성이 잔재하였다. 이 논문은 C. atlanticus 리파아제의 발현, 특성규명, Cross-linked Enzyme Aggregated 고정화를 바탕으로 안정성을 높여 산업적 활용 가능성을 제시한 최초의 보고이다.

• Ocean and Polar Research
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• 제41권4호
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• pp.265-274
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• 2019

To trace the provenance of fine-grained sediments in response to the growth and retreat of glaciers (i.e., Ross Ice Sheet) that affects the depositional process, various kinds of analyses including magnetic susceptibility, granulometry, and clay mineral composition with AMS ¹⁴C age dating were carried out using a gravity core KI-13-GC2 obtained from the Central Basin of the Ross Sea continental margin. The sediments mostly consist of silty mud to sand with ice-rafted debris, the sediment colors alternate repeatedly between light brown and gray, and the sedimentary structures are almost bioturbated with some faint laminations. Among the fine-grained clay mineral compositions, illite is highest (59.1-76.2%), followed by chlorite (12.4-21.4%), kaolinite (4.1-11.6%), and smectite (1.2-22.6%). Illite and chlorite originated from the Transantarctic mountains (metamorphic rocks and granitic rocks) situated to the south of the Ross Sea. Kaolinite might be supplied from the sedimentary rocks of Antarctic continent underneath the ice sheet. The provenance of smectite was considered as McMurdo volcanic group around the Victoria Land in the western part of the Ross Sea. Chlorite content was higher and smectite content was lower during the glacial periods, although illite and kaolinite contents are almost consistent between the glacial and interglacial periods. The glacial increase of chlorite content may be due to more supply of the reworked continental shelf sediments deposited during the interglacial periods to the Central Basin. On the contrary, the glacial decrease of smectite content may be attributed to less transport from the McMurdo volcanic group to the Central Basin due to the advanced ice sheet. Although the source areas of the clay minerals in the Central Basin have not changed significantly between the interglacial and glacial periods, the transport pathways and delivery mechanism of the clay minerals were different between the glacial and interglacial periods in response to the growth and retreat of Ross Ice Sheet in the Ross Sea.

• 한국수산과학회지
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• 제45권6호
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• pp.579-585
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• 2012

The proximate compositions and fatty acid profiles of Antarctic toothfish Dissostichus mawsoni that was caught in the southern Ross Sea (J, L) of the Antarctic Ocean were studied. The lipid contents of samples from J and L were 18.2 and 21.1%, respectively. The protein and ash contents were similar for samples J and L. The prominent fatty acids in the total lipids of the fish muscle were 18:1n-9, 16:1n-7, 16:0, 14:0, 18:1n-7, 20:5n-3 (eicosapentaenoic acid, EPA), and 22:6n-3 (docosahexaenoic acid, DHA). In addition, the total fatty acids of bycatch products in the toothfish stomachs (Pleuragramma antarcticum, Gerlachea australis, Pasiphaea sp., Trematomus eulepidotus, Chionodraco hamatus, Chionodraco myersi, and Neopagetopsis ionah) were determined. The prominent fatty acids in those species were 18:1n-9, 16:0, 14:0, DHA, EPA, and 18:1n-7.

• Journal of Microbiology and Biotechnology
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• 제34권5호
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• pp.1135-1145
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• 2024

When cells are exposed to freezing temperatures, high concentrations of cryoprotective agents (CPA) prevent ice crystal formation, thus enhancing cell survival. However, high concentrations of CPAs can also cause cell toxicity. Exopolysaccharides (EPSs) from polar marine environments exhibit lower toxicity and display effects similar to traditional CPA. In this study, we sought to address these issues by i) selecting strains that produce EPS with novel cryoprotective activity, and ii) optimizing culture conditions for EPS production. Sixty-six bacteria producing mucous substances were isolated from the Ross Sea (Antarctic Ocean) using solid marine agar plates. Among them, Pseudoalteromonas sp. RosPo-2 was ultimately selected based on the rheological properties of the produced EPS (p-CY02). Cryoprotective activity experiments demonstrated that p-CY02 exhibited significantly cryoprotective activity at a concentration of 0.8% (w/v) on mammalian cells (HaCaT). This activity was further improved when combined with various concentrations of dimethyl sulfoxide (DMSO) compared to using DMSO alone. Moreover, the survival rate of HaCaT cells treated with 5% (v/v) DMSO and 0.8% (w/v) p-CY02 was measured at 87.9 ± 2.8% after freezing treatment. This suggests that p-CY02 may be developed as a more effective, less toxic, and novel non-permeating CPA. To enhance the production of EPS with cryoprotective activity, Response Surface Methodology (RSM) was implemented, resulting in a 1.64-fold increase in production of EPS with cryoprotective activity.

• 대한원격탐사학회지
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• 제34권6_2호
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• pp.1179-1192
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• 2018

이 연구는 남빙양(Southern Ocean)에서 나타나는 주된 전선(Front)들 중에 남극 극 전선(Antarctic Polar Front; PF)을 탐지하기 위하여 위성 기반 해수면 온도(sea surface temperature)와 해수면 고도(sea surface height) 자료를 복합적으로 사용하였다. 정확한 PF 탐지를 위하여 일별 SST와 SSH 자료를 각각 기반으로 하여 베이지안 결정 이론(Bayesian decision theory)을 적용하였으며, 이를 근거로 전선/비전선의 신호를 격자 별로 분류하였다. 이후, 시공간적인 합성을 통하여 일차적인 노이즈(noise) 제거 및 지리학적 연결성을 보완하였다. 그러나 이들 과정을 수행하고도 여전히 잔존하는 일부 노이즈를 제거하기 위하여 해빙 및 연안 마스킹(masking)을 수행하였다. 또한 모폴로지 연산(morphology operation)을 통하여 지류 성분을 최대한으로 배제하고 주된 전선 성분만을 추출하였다. 최종적으로 선택된 전선 격자 들에서 PF의 특징을 나타낼 수 있도록 가장 최남단의 전선만을 선택하여 평활 스플라인(smoothing spline) 최적화 방식을 통해 선 형태의 월별 PF를 산출하였다. 산출된 PF는 기존의 연구에서 제시한 PF의 위치와 상당히 유사한 것으로 나타났으며, 특히 바닥 지형에 따라 상당 부분 결정되는 PF의 변화를 잘 모사하는 것으로 보인다. 로스해 주변(${\sim}180^{\circ}W$)과 호주 이남의 해역($120^{\circ}E-140^{\circ}E$)은 PF의 위치에 대한 계절적 변동이 높게 나타나며, 그러한 변동이 기존에 제시된 결과와 상당히 유사한 경향을 지닌다. 그러므로 이 연구에서 산출된 PF의 위치에 대한 탐지 결과가 향후 장기적 관점에서 수행될 연구에 사용될 수 있는 가치를 지닐 것으로 기대한다.

• 한국해양생명과학회지
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• 제8권1호
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• pp.43-49
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• 2023

본 연구에서는 남극 로스해 연안에 서식하는 아델리펭귄(Pygoscelis adeliae)과 황제펭귄(Aptenodytes forsteri)의 분변 시료를 기반으로 펭귄 장내 미생물 메타지놈 연구를 수행하였다. Taxonomy 분석 결과, 아델리펭귄과 황제펭귄의 장내 미생물에는 주로 7개의 문(phylum), 18개의 과(family)가 존재하는 것으로 나타났다. 또한 미생물 다양성을 평가하기 위해 Alpha diversity 및 OTU abundance 분석을 수행한 결과, 전반적으로 아델리펭귄의 장내 미생물 다양성이 황제펭귄보다 높은 것을 확인하였고, PCoA를 기반으로 한 Beta diversity 분석을 통해 두 개체군 간 장내 미생물 군집에 차이가 존재함을 확인하였다. PICRUSt를 활용한 기능적인 차원의 KEGG pathway 분석을 통해서는 아델리펭귄과 황제펭귄 시료에서 nucleoside and nucleotide biosynthesis pathway가 가장 많이 존재하는 것을 확인하였다. 본 연구를 통해 남극 아델리펭귄과 황제펭귄의 장내미생물 구성과 다양성을 비교분석 할 수 있었다. 본 연구 결과는 향후 펭귄의 먹이 섭식 관련 연구에 활용될 수 있으며, 더 나아가 다양한 남극 생물의 장내미생물 메타지놈 분석에 대한 기초가 될 수 있을 것이다.