南极菲尔德斯半岛潮间带南极帽贝的种群生态学研究——空间分布图式

STUDIES ON POPULATION ECOLOGY OF THE LIMPET NACELLA CONCINNA IN THE INTERTIDAL ZONE OF FILDES PENINSULA, ANTARCTIC——SPATIAL DISTRIBUTION PATTERNS

1994年 1 2月— 1 995年 3月在南极菲尔德斯半岛潮间带进行了定点南极帽贝种群空间分布的调查研究。结果表明 ,无论所在底质、样方大小如何 ,所有调查种群均呈聚集分布。对 6个小尺度样方样本进行种群水平下空间结构分析得知 :分布的基本成分是疏松的个体群 (colony) ,个体群的分布是聚集的且可能是由环境异质性所引起的 ;个体在个体群内的分布是随机的。帽贝在岩石滩的个体群较大 (面积为 0 0 4— 0 1 6m2 ) ,在卵石滩较小 ( 0 0 1—0 0 4m2 ) ,在垂直岩面亦较小 ( 0 0 1m2 )。随时间变化 ( 1 994年 1 2月— 1 995年 3月 ) ,帽贝的聚集度 (m )随种群密度的下降而有所降低。在排除密度因子以后 ,聚集指标m /m的数值大多稳定在 3 61— 4 77之间。

From December 1994 to March 1995, spatial distribution patterns of the limpet population, Nacella concinna were investigated in the intertidal zone of Fildes Peninsula, Antarcitic. The intertidal ecosystem was classified into pebble, rocky and vertical rocky shores according to their substrates and slopes. The data were classified into large and small sample size sets, for pebble shore and rocky shore. We recorded the limpet number in each grid. In order to identify the spatial distribution of the limpet population, we compared the observed frequency distribution with the theoretical by probable frequency by using Poisson, Neyman A and Negative Binomial Distributions. During the experiment, limpet population, regardless to its sample size and substrates, all showed an aggregated distribution pattern. All samples of small size (0.1×0.1m 2 or 0.2×0.2m 2) fitted to the Negative Binomial Distribution. Samples of large size (1×1m 2) fitted well to Iwao’s model. However, the improved Iwao’s model could fit better ( m *=12.996 5+0.177 1 m +0.250 8 m 2 ). Samples of small size fitted to Iwao's model ( m *=-0.052 5+5.010 8 m ),but α <0, and β >1 was not statistically significant. The populations were comprised of loose colonies. The distribution of the colonies showed an aggregated pattern, and individuals within the colonies distributed randomly. On rocky substrates, colony sizes were relatively big (0.04 to 0.16m 2), but smaller on pebble (0.01 to 0.04m 2) and vertical rock (0.01m 2) substrates. During the austral season, index of mean crowding ( m *) decreased with the population density. Excluding the density effect, m */m is generally stabilized between 3.61 and 4.77.