启东市潮间带软体动物和腕足动物分布及其影响因子分析

Distribution of Mollusks and Brachiopods in Intertidal Zone,Qidong City and Their Influence Factors

大型底栖动物是重要的滨海渔业资源和迁徙水鸟的食物来源,研究大型底栖动物群落的多样性、分布及其影响因子,是保护和修复滨海湿地的迫切需求。2019年4月16日至18日,对江苏省启东市长江入海口北侧的潮间带的大型底栖动物进行了采样调查,研究了软体动物和腕足动物群落的组成、分布和它们生存的潮间带的环境差异;采用冗余分析方法,分析了环境因子对软体动物和腕足动物群落分布的影响。研究结果表明,在启东市潮间带共分布着16种软体动物和1种腕足动物,优势物种为四角蛤蜊(Mactra veneriformis)、托氏昌螺(Umbonium thomasi)和文蛤(Meretrix meretrix),其中,四角蛤蜊的密度最大,为95.90 ind./m^(2);在空间分布上,距离海堤500 m的断面的软体动物的物种数量最多,其显著多于距离海堤1000 m和1250 m的断面的物种数量;距离海堤750 m的断面的物种密度最大,其显著大于距离海堤1250 m的断面的物种密度;距离海堤500 m的断面的软体动物群落的Shannon-Weiner多样性指数和Pielou均匀度指数都最大,距离海堤750 m的断面的软体动物群落的Simpon多样性指数最大;研究区潮间带沉积物主要由粒径125-250 mm的细砂[占总砂砾量的(38±16)%]和粒径250-500 mm的中砂组成[占总砂砾量的(36±23)%],除了距离海堤1000 m的断面的黏土含量显著高于距离海堤500 m的断面外,其余各断面间沙砾的组成都无显著差异;粒径50-125 mm的特细砂含量和与海堤的距离是显著影响启东市潮间带软体动物和腕足动物群落密度的主要因素;优势物种四角蛤蜊的密度与其距海堤的距离显著正相关,托氏昌螺的密度与其距海堤的距离显著负相关。

Macrobenthos is an important coastal fishery resource and food source for migratory waterfowls,and it is an urgent demand of protection of coastal wetlands and restoration to study the diversity and distribution of macrobenthos communities and their influencing factors. From April 16-18, 2019, a sampling survey on mollusks and brachiopods in the intertidal flat on the north side of the estuary of the Yangtze River was conducted in Qidong city, Jiangsu province. The composition and distribution of mollusks and brachiopods community and the environmental differences of the intertidal flat where they live were studied;and the influence of environmental factors on the distribution of mollusks and brachiopods was analyzed by means of redundancy analysis. The results showed that there were 16 species of mollusks and 1 species of brachiopod in the intertidal flat of Qidong city, and the dominant species were Mactra veneriformis, Umbonium thomasi and Meretrix meretrix, and the density of Mactra veneriformis was 95.90 ind./m^(2), the highest among the dominant species. In terms of spatial distribution, the number of species was the highest at the cross section of 500 m from the seawall, which was significantly higher than those at the cross section of 1000 m and cross section of 1250 m;the species density of mollusks was the greatest at the cross section of 750 m from the seawall, which was significantly higher than that at the cross section of 1250 m. Both the Shannon-Weiner diversity index and Pielou evenness index of mollusks community were the highest at the cross section of 500 m away from the seawall, while the Simpon diversity index of mollusks community was the highest at the section of 750 m from the seawall. The sediment of the intertidal flat in the study area was mainly composed of fine sand with particle diameter of 125-250 mm(accounting for(38±16)% of the total sand) and medium sand with particle diameter of 250-500 mm(accounting for(36±23)% of the total sand). There were no notable differences in the gravel composition among the other sections, except that the clay content at the cross section of 1000 m from the seawall was significantly higher than the clay content of the cross section of 500 m from the seawall. The results showed that the content of fine sand with particle diameter of 50-125 mm and the distance from the seawall were the major factors significantly affecting the density of mollusks and brachiopods in intertidal flat,Qidong city;the density of the dominant species Mactra veneriformis was significantly positively correlated with its distance from the seawall, and the density of Umbonium thomasi was negatively correlated with and its distance from the seawall.