大鹏澳水域秋季浮游植物优势种的演替及其与春季的比较

根据2002年11月在亚大湾大鹏澳进行的连续30d(每日采样一次)观测资料，运用主成分分析和多元回归分析相结合方法，分析大鹏澳非养殖区中各浮游植物优势种之间的关系及影响其生长与演替的主要理化因子．建立秋季浮游植物优势种演替模型，并与春季的大鹏澳现场调查建立的浮游植物优势种演替模型进行比较，分析生境变化(降雨)对浮游植物优势种演替过程的影响。结果表明，春，秋季浮游植物优势种发生不同的演替过程。春季浮游植物对资源的竞争较为激烈，大量降雨引起海水中营养盐浓度升高，促进并维持中肋骨条藻(Skeletonema costatum)高密度生长，待营养盐被大量消耗后，中肋骨条藻数量下降，减轻了对柔弱菱形藻(Nitzschia delicatissima)的生长压力而使其成为优势种；而秋季水温较低，浮游植物细胞数量较春季大为减少，中肋骨条藻和柔弱菱形藻对资源的竞争较为缓和，使外界环境变化成为影响优势种变化的主要原因；降雨期间虽然营养盐增加，但环境变化使浮游植物的生长受到限制，雨后柔弱菱形藻数量不能恢复，水体中高营养盐浓度促使中肋骨条藻出现生长峰值。

SUCCESSION OF DOMINANT PHYTOPLANKTON SPECIES IN AUTUMN AND SPRING IN WATERS OF DAPENG'AO COVE, DAYA BAY, GUANGDONG PROVINCE

Two 30-day in situ observations were carried out in May and November 2002 respectively at the Dapeng'ao Cove, a semi-enclosed cove in the southwest of the Daya Bay, Guangdong Province. Analyses of the relationships among the dominant species and the major physical-chemical factors were performed with the methods of principal component analysis and multiple regression analysis, and a dominant species succession model was established. The comparison between the succession models for spring and autumn revealed that rainfall had a significant impact on the succession process. In spring, phytoplankton density was high and their competition for resource was strong. When it rained, a great deal of nutrients was brought into the cove and accelerated the growth of Skeletonema costatum. After nutrients were exhausted, S. costatum could not maintain a high density, which reduced its growth stress on Nitzschia delicatissima and made it become dominant. In autumn, although nutrient concentrations in the waters were high, phytoplankton density was much lower than that in spring and their competition for resource was mitigated, and the succession of the dominant phytoplankton species was mainly influenced by environmental factors. After rain, the growth of N. delicatissima was limited, while the growth of S. costatum was promoted by high nutrient concentrations.