How will the Antarctic terrestrial invertebrates respond to the change in the ambient temperature?

第6回極域科学シンポジウム[OB] 極域生物圏11月16日（月）　国立極地研究所１階交流アトリウ

Tardigrades in the lakes in Skarvsnes, Dronning Maud Land, Antarctica

第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月27日（火） 国立極地研究所 ３階ラウン

南極コケ植物相の起源

第6回極域科学シンポジウム分野横断セッション：[IB2] 地球環境変動の解析と地球生命システム学の構築11月19日（木）　統計数理研究所 セミナー室1（D305

Micro-relief distribution of major mosses in ice-free areas along the Soya Coast, the Syowa Station area, East Antarctica

Micro-relief distribution of five major mosses, Pottia heimii, Ceratodon purpureus, Bryum pseudotriquetrum, Grimmia lawiana and Bryum argenteum, in the ice-free areas along the Soya Coast, continental part of East Antarctica have been compared. Those five mosses showed three different types of micro-relief distribution, at three different types of sites: mounds, slopes and hollows. Pottia heimii and Ceratodon purpureus prevailed on mound sites mixed with cyanobacteria. In dryer mound environments cyanobacteria was supposed to play an important role in nitrogen fixation. Bryum pseudotriquetrum and Grimmia lawiana dominated on hollow sites covered with sand. A more moisture rich condition of the hollow may promote their abundance associated with their high photosynthetic ability at moist sites. Bryum argenteum showed a rather unclear micro-relief distribution pattern. It appeared chiefly on mounds, but on hollows also. Rich nutrient input by sea birds into its habitats may allow various site selection under environments favorable to distribution

Structure and dynamics of the Ceratodon purpureus-Bryum pseudotriquetrum community in the Yukidori Valley, Langhovde, continental Antarctica

The structure and dynamics of the Ceratodon purpureus-Bryum pseudotriquetrum community along the Yukidori Valley, Langhovde near Syowa Station, continental Antarctica have been documented. This moss community showed a clear vegetation structure with a micro-relief distribution, consisting of three different sites; a mound, a slope and a hollow. On the hollow site a sand-covered Bryum pseudotriquetrum patch dominated. On the slope site a pure Ceratodon purpureus patch, a Bryum pseudotriquetrum patch, and a Ceratodon purpureus-Bryum pseudotriquetrum mixed patch abundantly occurred. On the mound site a cyanobacteria-mixed Ceratodon purpureus patch prevailed. The dynamics of this community was basically unclear. However, some change patterns were infered from the results. The sand-covered Bryum pseudotriquetrum patch and the cyanobacteria-mixed Ceratodon purpureus patch generally showed no clear change. It is also speculated that some of the patches of this community undergo cyclic changes. A suggested cyclic pattern is as follows; some of the sand-covered Bryum pseudotriquetrum patches turned on Ceratodon purpureus-Bryum pseudotriquetrum mixed patches, and finally those patches became a cyanobacteria-mixed Ceratodon purpureus patch. Some of them, on the other hand, degraded into sand-covered Bryum pseudotriquetrum patches, probably because of strong wind or water flow. However, more detailed studies will be needed to confirm these inferences

Xanthophyll-cycle of ice algae on the sea ice bottom in Saroma Ko lagoon, Hokkaido, Japan

Using the ice algal community prevailing on the sea ice bottom in Saroma Ko lagoon, Hokkaido, Japan, the response of a photosynthetic system to exposure to light was investigated, focusing on xanthophylls-cycle features, diel changes of the pool size of xanthophylls-cycle pigments and the effective quantum yield of PS II in early February, 1998. By pigment analysis, β-carotene, chlorophylls a and c, diadinoxanthin, diatoxanthin and fucoxanthin were detected as major pigments, which suggests that diatoms dominated as ice algae during this study. When such ice algae were exposed to irradiance nearly 4 times higher than the daily maximum level at the ice bottom, the interconversion between diadinoxanthin and diatoxanthin continued for ca. 20 min immediately after the onset of irradiation in spite of the sub-zero Celsius ambient temperature. Although the pool size of this xanthophylls-cycle (relative amount of diadinoxanthin plus diatoxanthin per chlorophyll a) was not so large compared to that of mesophilic diatoms, it showed a circadian change increasing during the daytime and decreasing at night. This change correlated well with the effective quantum yield of PS II. These results suggest that ice algae at the sea ice bottom possess a relatively effective xanthophylls-cycle to regulate light energy usage. However, the xanthophylls-cycle in ice algae may be poor compared to that of algae living in intermediate irradiance, which can be interpreted from the point of view of bioenergetic aspects of shade adapted ice algae

Diatoms composing benthic microbial mats in freshwater lakes of Skarvsnes ice-free area, East Antarctica

Diatoms composing benthic microbial mats in Skarvsnes lakes, East Antarctica, were studied in terms of their taxonomy and relationship to environmental factors. Samples were collected from 13 freshwater lakes in the area. Amphora sp. (cf. veneta) was dominant in 11 of the 13 samples, while Craticula sp. (cf. molesta) and Diadesmis sp. (cf. perpusilla) were respectively dominant in the remaining 2 samples. Navicula ectoris Van de Vijver was also reported here for the first time in continental Antarctica. Mosses in the microbial mats did not have a significant effect on the diatom species composition. Redundancy analysis revealed that the main environmental gradient for diatoms was electric conductivity, despite its relatively narrow range (18-390 mS m^(-1)). Our results suggest that Diadesmis sp. and Psammothidium metakryophilum are halophobes, whereas Amphora sp. is a halophile