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The Impacts of climate change on Antarctic nearshore mega-epifaunal benthic assemblages in a glacial fjord on King George Island: Responses and implications

Thu, 01 Jan 2015 00:00:00 GMT

Title: The Impacts of climate change on Antarctic nearshore mega-epifaunal benthic assemblages in a glacial fjord on King George Island: Responses and implications Authors: Ahn, In-Young; WMR Wan Hussin; Moon, Hye-Won; Kim, Hyun-cheol Abstract: We examined the impacts of climate change on Antarctic nearshore marine benthic communities on the West Antarctic Peninsula, one of the most rapidly warming regions on earth. We surveyed the epibenthic megafaunal assemblages of Marian Cove, a representative fjord on King George Island. We collected specimens by SCUBA diving at varying distances from the retreating glacier front during the 2013/2014 austral summer. Based on presence/absence data from the collected taxa, we determined species richness (S), taxonomic distinctness (TD) and functional diversity (FD) and further analyzed differences in assemblages in relation to environmental characteristics. Faunal assemblages in the inner cove (ice-proximal zone) were compositionally distinct from those in the outer cove. Species number and FD were also lower in the inner cove and tended to increase toward the outer cove. Nonetheless, TD values were similar among sites, indicating that all sites were distinct taxonomically. This may be because glacier retreat affected organisms of lower taxonomic levels the most. Multivariate and univariate analyses demonstrated that these differences were significantly related to distance from the glacier, substrate grain size, and organic content. The high correlation (r = 0.909, P < 0.01) of assemblages with distance from the glacier front suggests that physical disturbance by ice is a major process shaping benthic communities. Thus, we provide evidence that glacier retreat and its consequent processes impact the structure and function of communities. With their spatial pattern significantly associated with environmental suites, nearshore megabenthic communities respond sensitively and measurably to climate-induced impacts, suggesting their utility as long-term biomonitors. As a small but confined glacial cove with very distinct environmental gradients related to climate-induced processes, Marian Cove could serve as a model ecosystem for assessing climate impacts on Antarctic nearshore benthic communities.

Transcriptome information of the Arctic green sea urchin and its use in environmental monitoring

Wed, 01 Jan 2014 00:00:00 GMT

Title: Transcriptome information of the Arctic green sea urchin and its use in environmental monitoring Authors: Lee, Jae-Seong; Lee, Jae-Seong; Ahn, In-Young; Park, Hyun; Choi, Ik-Young; Choi, Beom-Soon; Kim, Bo-Mi Abstract: The Arctic sea urchin Strongylocentrotus droebachiensis is considered to be a potential indicator species for assessing aquatic environmental conditions in the polar region. To develop a gene resource for the Arctic sea urchin, we sequenced S. droebachiensis cDNAs using a GS-20 sequencer and obtained expressed sequence tags information. In the assembly stage, 31,526 transcripts were obtained and showed a 32 % hit rate in the GenBank nonredundant database with 9,995 unigenes. Of the transcripts obtained in this species, we found several stress- and cellular defense-related genes (antioxidant-related genes and genes from the heat shock protein family) that are useful for the monitoring of pollutant-triggered stress responses at the molecular level. To validate the usefulness of these potential biomarker genes, we analyzed the transcript profiles of selected genes in response to polychlorinated biphenyls (PCB) mixtures (Aroclor 1254) for 48 h. PCB contamination is a present-day threat to the health of individual organisms and ecosystems in the polar region. We showed that 11 of 14 genes responded to PCB treatment at transcriptional levels, with the most dramatic upregulation observed in the hsp70.5 gene. In this paper, we summarize the expressed cDNA information and discuss its potential use in ecotoxicological genomic studies on PCB exposure.

Effect of ultraviolet irradiation on the production and composition of fatty acids in plankton in a sub-Antarctic environment

Wed, 01 Jan 2014 00:00:00 GMT

Title: Effect of ultraviolet irradiation on the production and composition of fatty acids in plankton in a sub-Antarctic environment Authors: Ha, Sun-Yong; Shin, Kyung-Hoon; Ahn, In-Young; Kang, Sung-Ho; Joo, Hyong-Min Abstract: We investigated the effects of ultraviolet-B (UV-B) radiation on the natural phytoplankton assemblage in Marine Cove on King George Island, Antarctica, in December 2005. The amount of newly synthesized phytoplankton polyunsaturated fatty acids (PUFAs) was lower with exposure to full irradiation (PAR?UV-A?UV-B) than without such exposure (exposed instead to PAR?UVA radiation) in an in situ incubation under the light conditions in two different types of incubation bottles: quartz bottles transmitting all light wavelengths including UV-B and polycarbonate bottles with no UV-B transmission and 20 % reduced PAR compared to the quartz bottle. However, the amount of newly synthesized saturated fatty acids was greater with than without UV-B radiation. Thus, UV-B radiation may have a significant influence on fatty acid synthesis in phytoplankton. In particular, the production of eicosapentaenoic acid [20:5(n-3)] and docosahexaenoic acid [22:6(n-3)] was reduced during incubation under the natural solar radiation including UV-B. To understand the indirect influence of UV-B on herbivores (the secondary producer), we conducted feeding experiments with amphipods fed in situ on the natural phytoplankton assemblage. The amphipods fed on the phytoplankton with the low PUFA values also exhibited a low PUFA accumulation rate, which could negatively affect their growth, development, and reproduction. Consequently, the diminished rate of essential fatty acid synthesis [especially 20:5(n-3) and 22:6(n-3)] in primary producers caused by UV-B exposure could affect the structure and function of the Antarctic marine ecosystem.

Spatial Distribution Patterns of the Antarctic Hair Grass Deschampsia antarctica in Relation to Environmental Variables on Barton Peninsula, King George Island

Tue, 01 Jan 2013 00:00:00 GMT

Title: Spatial Distribution Patterns of the Antarctic Hair Grass Deschampsia antarctica in Relation to Environmental Variables on Barton Peninsula, King George Island Authors: Ahn, In-Young; Park, Jeong Soo; Lee, Eun Ju Abstract: Understanding the patterns in species distribution and abundance along environmental gradients is a keystone in field ecological study. Because the Antarctic terrestrial communi-ties are simple, they provide a suitable opportunity for studying species distribution patterns in relation to environmental gradients. We applied diverse geostatistic methods and classi- cal statistic descriptors to analyze the spatial patterns of several variables, such as Descham- Korea psia antarctica abundance, moss cover, topography, and soil physical and chemical proper- ties. Directional semivariograms and kriged maps showed that strong anisotropy in a topographic variable was reflected in the soil variables. Especially, soil texture and moss cover were correlated with elevation, and electric conductivity and Na were influenced by the distance from the shoreline. Furthermore, the heavy snowfall in 2009 evidently affected the survival of the grass. A short growing period and waterlogging induced by heavy snowfall may limit survival of D. antarctica and the amount of snowfall can be a important factor limiting the grass expansion.ying species distribution patterns in relation to environmental gradients. We applied diverse geostatistic methods and classi- cal statistic descriptors to analyze the spatial patterns of several variables, such as Descham- Korea psia antarctica abundance, moss cover, topography, and soil physical and chemical proper- ties. Directional semivariograms and kriged maps showed that strong anisotropy in a topographic variable was reflected in the soil variables. Especially, soil texture and moss cover were correlated with elevation, and electric conductivity and Na were influenced by the distance from the shoreline. Furthermore, the heavy snowfall in 2009 evidently affected the survival of the grass. A short growing period and waterlogging induced by heavy snowfall may limit survival of D. antarctica and the amount of snowfall can be a important factor limiting the grass expansion.