冬季大连砂质潮间带自由生活海洋线虫群落结构及多样性的比较

本研究于2015年12月在濒临渤海的大连夏家河子沙滩和濒临黄海的大连金沙滩采集海洋线虫样品，对两处砂质潮间带海洋线虫群落结构及多样性特征进行了研究。研究结果表明，两处砂质潮间带海洋线虫丰度、优势种、摄食结构及多样性差异显著。夏家河子海洋线虫平均丰度为(592.0±318.9) ind./(10 cm2)，金沙滩海洋线虫平均丰度为(54.6±53.8) ind./(10 cm2)，显著低于夏家河子。共鉴定海洋线虫43种，共有种13个。夏家河子沙滩海洋线虫优势种为Daptonema sp.1、Daptonema sp.2、Theristus sp.1、Setosabatieria sp.1、Prochromadorella sp.1、Daptonema sp.3、Paracyatholaimus sp.1、Sabatieria breviseta，以非选择性沉积食性线虫为主；金沙滩海洋线虫优势种为Oncholaimus sp.1、Chromadorita sp.1、Theristus sp.2, Neochromadora sp.1、Enoplus sp.1、Prochromadorella sp.1，以杂食性或捕食性线虫为主。两处砂质潮间带海洋线虫种数S、丰富度指数d和香农?威纳多样性指数H'存在极显著的差异，其值均表现为夏家河子显著高于金沙滩。相似性分析结果显示，两处沙滩的海洋线虫群落结构存在显著差异。间隙水pH、沉积物有机质含量及中值粒径是引起海洋线虫群落结构及多样性差异的主要因子，其中，沉积物中值粒径对线虫群落特征的影响最为突出。就两处沙滩潮区差异而言，受沉积物粒径特征及pH的影响，夏家河子海洋线虫群落特征在不同潮区之间也存在差异，其低潮带海洋线虫多样性高于高、中潮带，杂食者和捕食者丰度高，反映其海洋线虫群落结构较复杂。金沙滩不同潮区的环境因子无显著差异，线虫群落结构及多样性潮区差异不显著，较为均一。此外，水动力对海洋线虫群落结构沙滩差异和潮区差异也产生重要影响。一方面，水动力通过影响不同粒径沉积物的沉积影响海洋线虫群落特征；另一方面，水动力可影响线虫的分散性，进而对其潮区分布产生影响。

Comparison of community structure and diversity of free-living marine nematodes in the sandy intertidal zone of Dalian in winter

In this study, marine nematode samples were collected from Dalian Xiajiahezi Beach near the Bohai Sea and Dalian Golden Beach near the Yellow Sea in December 2015, and the community structure and diversity characteristics of marine nematodes in two sandy intertidal zones were studied. The results showed that there were significant differences in the abundance, dominant species, trophic structure and diversity of marine nematodes at the two beaches. The average abundance of marine nematodes were (592.0±318.9) ind./(10 cm2) in the Xiajiahezi Beach, and (54.6±53.8) ind./(10 cm2 ) in the Golden Beach, which was significantly lower than that in the Xiajiahezi Beach. A total of 43 species of marine nematodes were identified, and 13 common species. The dominant species of marine nematodes in the Xiajiahezi Beach were Daptonema sp.1, Daptonema sp.2, Theristus sp.1, Setosabatieria sp.1, Prochromadorella sp.1, Daptonema sp.3, Paracyatholaimus sp.1, Sabatieria breviseta, which were mainly non-selective sedimenous nematodes. The dominant species in the Golden Beach were Oncholaimus sp.1 Chromadorita sp.1, Theristus sp.2, Neochromadora sp.1, Enoplus sp.1, Prochromadorella sp.1, which were mainly omnivorous or predatory nematodes. There were significant differences in species number (S), Margalef’s species richness (d) and Shannon–Wiener index(H′) between the two sandy beaches, and the values were significantly higher in the Xijiahezi Beach than the Golden Beach. The Analysis of Similarity tests (ANOSIM) results showed that there were significant differences in marine nematodes community structure between the two beaches. Interstitial water temperature and median diameter (MD_Φ) were the main environmental factors that cause differences in marine nematode community structure and diversity. The characteristics of the marine nematodes community in the Xijiahezi Beach were also different among different tidal zones due to the variations of sediment granularity and pH. The diversity of marine nematodes in low tidal zone was higher than that in high and mid tidal zones, and the abundance of omnivores and predators was higher, which reflected the complex structure of the marine nematodes community. In the Golden Beach, there was no significant difference in environmental factors in different tidal zones, and the difference in nematodes community structure and diversity of tidal areas was not significant and relatively uniform. In addition, hydrodynamic force function was also an important factor that causes differences in marine nematode community structures at the studied beaches. On the one hand, hydrodynamic force affected the community characteristics of marine nematodes by influencing the deposition of sediments with different particle sizes. On the other hand, hydrodynamic force could affect the dispersity of nematodes which in turn affects their tidal distribution.