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

Status and future of the research on Polar terrestrial biology

第2回極域科学シンポジウム/第33回極域生物シンポジウム 11月18日（金） 統計数理研究所 3階セミナー室

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

On the structures of moss colony in the Yukidori Valley, Langhovde, East Antarctica

The moss vegetation developing in the Yukidori Valley, Langhovde, East Antarctica, was investigated as based on the samples in the vertical cross-section housed as the herbarium specimens to categorize the structure of the moss colony and to determine the specific composition. The vegetation consists of pure colonies of one species, and mixed colonies composed of two or rarely three moss species. Each colony was classified by species composition and degree of unevenness. The active zone, decomposed zone which were seen in the vertical cross-section, and epiphytic condition on the surface such as cyanobacteria and imperfect lichens, and rhizoidal layers in the inside of colony were determined and measured. Furthermore, the relationship between epiphytic condition and the thickness of the pure and mixed colonies was discussed taking account of ecological significances of these structural features

Ecological studies of aquatic moss pillars in Antarctic lakes 2. Temperature and light environment at the moss habitat

To understand the environmental conditions, which control the growth of moss pillars in lake bottoms, water temperature and light in the moss pillar habitat in lake Kuwai Ike in Skarvsnes, Soya Coast, East Antarctica, were continuously measured for about one year, February 1999 to Jannuary 2000. Limnological characteristics of surface water of the lake were investigated in summer 2000, and compared with those in four neighboring lakes. Low contents of ions, neutral pH and dissolved oxygen in saturation level in the surface water in Kuwai-Ike lake were comparable to the values of the other oligotrophic freshwater lakes in Soya Coast and Schirmacher Oasis, located in Queen Maud Land, East Antarctica. The temperature at the lake bottom showed uni-modal seasonal change, in the range 0-12°C. Several sudden temperature drops of > 2°C within a few hours were recorded in the ice-free autumn season; they may have been correlated with the wind-induced vertical mixing events which occurred before complete ice cover development on the lake surface. Light reaching the lake bottom showed clear diel and seasonal fluctuations, and the flux density was strongly affected by the attenuations of water, ice and snow: the photosynthetically active radiation (PAR) measured at the lake bottom was s^ was recorded for nearly 2 months in winter; however, daily fluxes over 1 mol m^ day^ were recorded for the other ca. 8 months, with >100μmol m^ s^ of instantaneous peak fluxes around noon

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