黄河口水下三角洲海洋线虫空间分布的研究

A STUDY ON SPATIAL PATTERN OF MARINE NEMATODES IN THE SUBAQUEOUS DELTA OF THE HUANGHE RIVER

本文是1987年10月对黄河口水下三角洲一个取样站(E_2站)的调查结果。该站水深10m;底质为粘土质粉砂,其粉砂和粘土的含量分别为51%和48%。小型动物的密度为(1315±752)×10~3 ind/m^2;自由生活海洋线虫占小型动物总丰度的86.7%,平均密度为(1140±662)×10~3 ind/m^2。扩散卡方检验表明,海洋线虫主要种群的分布为集合分布。异质性卡方值表明,在所研究的样品分离尺度上可作出微生境的划分。结合优势种食性类型的分析探讨了控制小尺度空间分布的机制。

During the autumn of 1987, a study of the abundance of free-living marine nematoda populations was carried out on a series of sixteen core samples taken with a 4 × 4 core sampler from a Gray-O'Hara box corer at station E2 in the subaqeous delta of Huanghe River (water depth 13m). Mean meiofauna abundance amounted to 1315±752×103 ind/m2. Free-living marine nematodes comprised 86.7% of the total meiofauna, with the mean density of (1140 ± 660) × 103 ind/m2. Harpacticoid copepods were second, constituting 9.9% of the total num- bers with the mean density of (130±80) ×103 ind/m2. Both the abundance and the percentage composition of the nematoda and harpacticoid copepods were similar to those obtained from the similar habitat in the summer of 1986.Species composition and spatial pattern of marine nematodes were examined from six continuous core samples selected from a series of sixteen samples from the same box corer. A total of 42 species were found. Low diversity (H'), ranging between 0.88 and 1.07, was typical of the uneven distribution of individuals among the species throughout the samples. Dispersion chi-square analysis indicated that the eighteen species, with occurrence frequency= 50% and cumulating abundance more than 95% of total nematodes populations, were in aggregation. Values of heterogeneity chi-square showed that the habitat partitioning was observed on the sample seperation scale (3cm). Calculation of dispersion chi-square without the first dominant species Dorylaimopsis sp. 1 and the first six species (occurrence frequency= 100%) showed that the chi-square values were still significant and that the remaining twelve species were still of nonrandom distribution.The analysis of feeding pattern of dominant and common species shows that the food availability and reproductive adaptation are the most likely important factors controlling the distribution of the aggregated populations in the 'special sedimentary environment