https://repository.kopri.re.kr/handle/201206/5265 2026-04-21T12:30:52Z https://repository.kopri.re.kr/handle/201206/13037 Title: Patterns, drivers and implications of ascidian distributions in a rapidly deglaciating fjord, King George Island, West Antarctic Peninsula Authors: Kim, Dong-U; Khim, Jong Seong; Ahn, In-Young Abstract: We report strong evidence for the utility of ascidian communities as sentinel organisms for monitoring nearshore Antarctic marine ecosystem response to climate-induced warming and glacial melting. Ascidians are one of the most common Antarctic epibenthic megafauna, but information on their distribution and the determinants is still scarce. In this study we investigated spatial patterns of ascidians in Marian Cove (MC), a rapidly deglaciating fjord in the West Antarctic Peninsula, one of the most rapidly warming regions on earth. We also analyzed key drivers structuring the communities and assessed their relevance to glacial retreat and following processes. The first applied ROV survey in MC discovered that ascidians were the most diverse (14 out of 64 taxa) taxa with the greatest abundance (~264 inds·m-2). Ascidian abundance and diversity greatly varied in space, by distance from glacier and/or depths, explaining ~64% of total megafaunal variations. Notably, in deep seabed (50？90 m) they shifted distinctly from early colonization communities near glacier (0.2 km to glacier) with predominance of two opportunistic species, Molgula pedunculata and Cnemidocarpa verrucosa, to mature communities at the most remote site (3.5 km). A set of analyses revealed that such shifts were related mostly to changes in sediment properties that develop in association with glacial retreat and consequent processes. Sediment composition, grain size and sorting collectively explained outward increasing physical stability apparently with decreased influence of glacial retreat, supporting ascidian community maturing at the deep and distant site. BIOENV analysis indicated that “distance” to glacier is one key factor influencing ascidian community structure in the deep seabed. Overall, the results of the analyses strongly indicated that physical disturbances (mainly sedimentation and ice scouring) accompanying glacial retreat are an important force shaping ascidian assemblages in the cove, and that these forces are altered by the distance from the glacier and water depth. Notably, in this fjord, the period of sea bed deglaciation was roughly proportional to the distance to glacier over the last six decades. This suggested that the ascidian shift identified in this study reflects a long-term successional process associated with glacial retreat in the past in MC, which in turn warrants to project future changes in this glacial fjord and possibly other similar environments. 2021-06-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10868 Title: Tight trophic association between benthic diatom blooms and shallow-water megabenthic communities in a rapidly deglaciated Antarctic fjord Authors: Ha, Sun-Yong; Ahn, In-Young; Moon, Hye-Won; Choi, Bohyung; Shin, Kyung-Hoon Abstract: This study reports isotopic evidence of a unique and highly efficient trophic structure based on a rarely reported benthic diatom species in a rapidly warming Antarctic fjord (Marian Cove; MC). Recent surveys of MC revealed a very conspicuous feature, an intense, persistent benthic diatom bloom ('benthic diatom bush') overgrowing a variety of common megabenthic fauna, primarily filter feeders (bivalves, ascidians, and demosponges), which occurred widely at shallow depths. To ascertain if the benthic diatom bloom is consumed as a primary food source, δ13C and δ15N were analyzed in the associated filter feeders and other herbivores, as well as in the diatom bush and other potential food sources (microphytobenthos, sedimentary organic matter and macroalgae). The analysis showed that the δ13C values of all filter feeders (？23.5 to ？25.2‰) were very similar to those of the diatom bush (？23.1 to ？23.6‰), strongly suggesting that these benthic diatoms are the principal diet of the associated filter feeders. The isotopic signatures of the other food sources were very close to those of the diatom bush, indicating that the organic matter had the same origin, namely benthic diatoms. Given its quality, quantity and availability, the diatom bush could be regarded as the primary food source. The benthic diatom bush was predominated by the chain-forming centric diatom Paralia sp., which occurs in shallow coastal waters with a wide range of salinity in various geographic localities. Thus, the Paralia sp. bloom in this rapidly warming fjord also indicates its potential utility as an indicator of climate-induced environmental changes. Additional isotopic analysis of other common fauna showed that the benthic food web in this fjord comprised up to four trophic levels of consumers, with starfish and isopods at the apex. Given that filter feeders comprise the largest trophic group in the cove and many other Antarctic coastal waters, the results of this study strongly suggest that benthic diatoms are of prime importance in supporting the benthic food web in MC, and possibly other nearshore Antarctic waters. Further studies on the mechanism underlying benthic diatom blooms and their relevance to climate-induced processes would provide better project future scenarios for rapidly warming fjord ecosystems. 2019-03-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10538 Title: Physiological Characteristics and Related Biochemical Parameters of Snow Algae from King George Island, Antarctica Authors: Kim, Bo Kyung; Joo, Hyong-Min; Lee, BoYeon; Lee, Dong-Hun; Ahn, In-Young; Ha, Sun-Yong Abstract: Red and green snow caused by snow algal blooms is common on glaciers and snowfields worldwide. Reddish and greenish snow samples containing algae were collected at the vicinity of penguin rockeries on King George Island (62°13'S, 58°47'W, near the King Sejong Station), Antarctica in February 2017 to investigate their physiology. Eight pigments and six fatty acids were detected from the samples. No difference in pigment and fatty acid (FA) composition was found between reddish and greenish snow samples. In contrast, spectral profiling and mycosporine-like amino acids (MAAs) were different between reddish and greenish snow. Particularly in greenish snow, a high absorbance between 450？600 nm was observed. The average MAA concentration was 316.0 μg g-1 in greenish snow, which was higher than that of reddish snow (278.2 μg g-1). The MAA to Particulate organic carbon (POC) ratio (mg (g C)-1) for reddish snow (6.2 mg (g C)-1) was higher than that of greenish snow (2.6 mg (g C)-1). These results suggest that reddish and greenish snow are considered to be the same species based on pigment and FA composition. Compared with photoprotective pigments, MAAs offer snow algae a more effective photoprotection strategy to promote tolerance of natural levels of ultraviolet radiation (UVR). 2018-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/12598 Title: Monitoring glacier retreat using time-series remote sensing imagery in Marian Cove, King George Island, Antarctica Authors: Hyun, Chang-Uk; Kim, Hyun-cheol Abstract: Antarctic Peninsula is known as the area experiencing prominent global warming than other places in Antarctica. An effective way to investigate environmental changes from warming is long-term monitoring using remote sensing technique. We chose Marian Cove, King George Island, Antarctica as a monitoring site located in Antarctic Peninsula. To investigate glacier retreat trend in the target area, multiple commercial and publicly available remote sensing datasets including aerial photography, mid-resolution, i.e., a spatial resolution of about 15 m, satellite imagery and high-resolution, i.e., a spatial resolution of about or less than 1 m, satellite imagery acquired in austral summer were collected from 1956 to 2017, over sixty years. The remote sensing datasets were carefully registered to compensate spatial displacement between datasets and then glacier terminus in each dataset was mapped. From the retreat velocity of the terminus lines, acceleration trend of glacier retreat in recent years was figured out, and this approach will be applied to other monitoring sites such as Potter Cove and Collins Harbor in the coast of King George Island in further study. 2018-01-01T00:00:00Z