南极乔治王岛雪藻的分布及其相关的雪物理和化学特征

DISTRIBUTION OF SNOW ALGAE AT KING GEORGE ISLAND, ANTARCTICA WITH REFERENCE TO PHYSICAL AND CHEMICAL CHARACTERS OF SNOW

研究了南极乔治王岛地区雪藻的分布和种类组成，以及相关的有色雪的物理和化学特征，如积雪性状、雪融水的ｐＨ、电导率和营养盐浓度，以便了解影响雪藻分布的环境因子。乔治王岛地区的大多数雪藻是属绿藻门的种类，与其他淡水生境相比，兰藻和硅藻数量稀少。利用菲尔德斯半岛和阿德雷岛沿岸的三种主要雪型研究雪藻群落的生态学：由绿藻的红色休眠细胞占优势的红色雪，由一种丝状绿藻（Ｋｌｅｂｓｏｒｍｉｄｉｕｍｓｐ．）占优势的绿色雪和由一种小球状的金藻占优势的褐色雪。红色雪和褐色雪趋向于以粗糙粒状雪的性状出现，而绿色雪则趋向于以渍水性雪的性状出现。所有有色雪的ｐＨ值处于同一水平（ｐＨ为５～６），但绿色雪融水的电导率和氨氮（ＮＨ４－Ｎ）浓度高于红色和褐色雪，且绿色雪的叶绿素ａ含量比红色雪高得多。有色雪的叶绿素ａ含量与ＮＨ４－Ｎ和ＰＯ４－Ｐ浓度的相关性不明显，但在所研究的环境因子中，雪的性状、雪融水的电导率和ＮＨ４－Ｎ浓度对雪藻的分布有影响。

Species composition and distribution of snow algae were studied at King George Island,Antarctica with reference to physical and chemical characters of colored snow such as snow condition,pH,conductivity and nutrient concentration of meltwater to assess the environmental factors influencing the distribution of snow algae. Most snow algae were members of Chlorophyta. Cyanophyceae and Bacillariophyceae were poorly represented compared with other freshwater habitats. Ecological studies were carried out on coastal communities of Fildes Peninsula and Ardley Island using three types of snow:red snow dominated by red resting cells of green alga,green snow dominated by a filamentous green alga, Klebsormidium sp. and brown snow dominated by a coccoid chrysophycean alga. Red and brown snow tended to occur on coarsely granulated,while,green snow tended to occur on waterlogged snow. Although pH was the same in all colored snow ( 5-6) , both conductivity and NH 4 N concentration in meltwater of green snow were higher than those of red and brown snow. Chlorophyll a contents of green snow were much higher than those of red snow. Relationship between Chlorophyll a content and nutrient concentrations of NH 4 N,PO 4 P were not clear in both red and green snow. Among studied environmental factors,snow condition,and both conductivity and NH 4J N in snow meltwater were considered to influence the distribution of snow algae.