南极沿海伯尔顿盐湖双刺镰状水蚤种群生态及其与盐湖环境的关系

对南极沿海伯尔顿盐湖浮游桡足类双刺镰状水蚤(Drepanopus bispinosus)种群生态进行了全年连续观察和研究,结果表明,该水蚤为一年一代,其个体发育周期,雄性约为10～12个月,雌性约为12～18个月。种群密度随季节不同而差异较大,其成体高密度期约在6～9月份,幼体高密度期大约在11～12月份,主要为无节幼体,桡足幼体Ⅰ期的高密度期出现在1月份。该水蚤繁殖期大约从6月至翌年1月,期间出现两次生殖高峰,7～8月为前一高峰期,所出现的无节幼体受环境因子主要是湖中食物和含氧量不足的影响而不能继续发育至桡足幼体Ⅰ期以上的阶段,后一高峰大约在10～12月,所出期的无节幼体能继续发育至桡足幼体各期直至成体。伯尔顿湖双刺镰状水蚤种群生态特征及其出现两次生殖高峰的现象,可能与该湖环境的季节变化有关。

CHARACTERISTICS OF THE INITIAL DENSIFICATION PROCESSES OF SNOW / FIRN IN WILKES LAND, ANTARCTICA

14 shallow snow / firn cores were taken by drilling with the PICO lightweight hand coring auger on Law Dome and Wilkes Land along a line approximately 111 °E longitude between 66°S and 74°S latitude. 5 of these cores, BJ, LJ24, GC30, GC40 and GC46, 20-30 m deep, are studied in detail in this paper. The densities of snow / firn were measured in a cold room at temperature between -18℃ and-14℃ by taking consecutive core samples and weighing the mass of each sample whose volume was known. The characteristics of the initial densification (till a density of 550 kg / m3) including the variation of snow / firn density with increasing depth, densification rate of snow / firn and the com-pactive viscosity coefficient of snow / firn are studied, and the factors affecting this initial densification process are discussed. From the obtained measurements, a relationship between compactive viscosity coefficient of snow / firn and mean annual temperature is found in case ρ=550 kg / m3 . For snow / firm on Wilkes Land, the relationship we found at a mean annual temperature below -25ccccccccccccccccc (i.e. no melting features are present in stratigraphy) is very similar to that found by Nishimura and others (1983) on Mizuho Plateau, Antarctica.