泉州湾蟳埔潮间带大型底栖动物群落的时空分布

为了比较泉州湾蟳埔潮间带沙滩、互花米草滩和牡蛎石泥滩3种生境(3个潮层)的大型底栖动物群落,2011年4月至2012年1月对3种生境的大型底栖动物进行了季度定量取样。在3种生境共获得85种大型底栖动物,其中环节动物39种,软体动物20种,节肢动物21种,刺胞动物、扁形动物、纽虫动物、星虫动物和脊索动物各1种。多维标度排序(MDS)分析表明,春季和冬季泉州湾蟳埔潮间带3种生境的大型底栖动物群落相似性较低;夏季和秋季互花米草滩与牡蛎石泥滩的大型底栖动物群落相似性较高,而与沙滩的大型底栖动物群落相似性较低。沙滩大型底栖动物群落的季节变化较明显,其次是牡蛎石泥滩,而互花米草滩大型底栖动物群落的季节变化较不明显。大型底栖动物栖息密度和生物量随着潮层降低而增加。单变量双因素方差分析(Two-way ANOVA)表明,不同生境之间的大型底栖动物物种数、栖息密度、多样性指数、均匀度指数和丰度指数有显著差异,但生物量无显著差异,这是因为沙滩的物种数较少,栖息密度较低,但优势种弧边招潮蟹(Uca arcuata)个体较大,互花米草滩和牡蛎石泥滩的优势种为加州中蚓虫(Mediomastus californiensis),个体相对弧边招潮蟹小。不同季节之间大型底栖动物物种数、栖息密度、生物量和丰度指数有显著差异,但多样性指数和均匀度指数元显著差异,这是因为沙滩物种数少,但个体分布比较均匀,而互花米草滩和牡蛎石泥滩物种数较多,个体分布较不均匀。以上结果表明,潮汐、沉积物粒径和生境是影响潮间带大型底栖动物群落的主要因素。潮汐导致潮间带的空间异质性,空间异质性导致大型底栖动物群落的差异。

Temporal and spatial variation of macrobenthic communities in the intertidal zone of Xunpu, Quanzhou Bay

This study was conducted in three different tidal levels within the intertidal zone of Xunpu, Quanzhou Bay, namely a sandy flat (on high-tide level), a Spartina alterniflora-dominated flat (on middle-tide flat) and an oyster-dominated flat (on middle-tide flat). Investigations were repeated four times between 2011 and 2012. We aimed to understand the spatial and temporal variation of macrobenthic community structure and to evaluate differences among three habitats in the study area. A total of 85 macrobenthic species were recorded, including 39 annelida (38 polychaeta and 1 oligochaeta), 21 crustacea, 20 mollusca (6 gastropoda and 14 bivalvia), 1 cnidaria, platyhelminthes, nemertea, sipuncula and chordata. The results of MDS analysis showed different macrobenthic communities among the three sites in spring and winter, while communities at the S. alterniflora-dominated and oyster-dominated flats were similar in summer and autumn. Within each season, the species number in the S. alterniflora-dominated flat was higher than that at the other two sites, probably due to a mixed sediment type and the shadowing of S. alterniflora acting as a shelter to animals. Instead, density and biomass of macrobenthos were higher at the two middle-tide flats than at the high-tidal flat. The temporal variation of macrobenthos was largest in the high-tidal flat and least in the S. alterniflora-dominated flat. With reduced tidal layer, density and biomass increased.Analysis of two-way ANOVA showed that in the three different habitats the species number, density, biodiversity, evenness and richness of macrobenthos were significantly different, while biomass was not. This because the species number and density were lower at the high-tide flat, dominated by the crab Uca arcuata, than at the other two sites, dominated by the polychaete Mediomastus californiensis. A comparison between different seasons showed that there were significant differences in species number, density, biomass and richness index, while diversity index and evenness index were not. This because the species number on the high-tide sandflat was low, but distribution was more even. The results indicate that larger tidal ranges and longer submerged time in summer and autumn cause more similarity of macrobenthic communities in the S. alterniflora-dominated and oyster-dominated flats. Overall, tidal level, sediment particle size and habitat type were the main factors affecting the temporal and spatial distribution of macrobenthos in Xunpu intertidal zone, Quanzhou Bay.