中国涠洲岛不同类型海岸现生微型腹足贝类群落研究

Study on the Community of Extant Microgastropod Mollusks among Different Types of the Coast of Weizhou Island, China

摘要: 为了探讨中国涠洲岛不同底质沿岸现生微型腹足贝类群落现况，依地貌类型特征，选择涠洲岛北边的贝壳沙滩、东海岸横岭沙滩和南湾沙滩等三样区进行微贝类物种调查。在各样区潮上带的壳积线上实施等距定点采集表层砂样，分别采得样沙6、5和6袋(约1公斤/袋)；经筛砂，分离出微型贝类遗壳；在总体中选择遗壳数量位居前十名的微型贝类物种，进行各区间群落組成比較分析。结果表明：三样区共获得遗壳标本2704个，其中蟹守螺科Cerithiidae微型贝类最多(37.1%)；物种丰富度为贝壳沙滩区 > 横岭沙滩 > 南湾沙滩区；特别是锥弯螺Pandalosia subulata与齿拟桂螺Pseudodaphnella caelata两物种广泛分布于贝壳沙滩区和东海岸沙滩区，而南湾区无采获。采得样砂依粒径大小分组比较，占各样区比例居多者，分别在贝壳沙滩区为砂样粒径大于0.43 mm粗砂組(42%)、横岭沙滩区为粒径介于0.126~0.25 mm细砂组(48%)和南湾海滩区则为粒径介于0.067~0.125 mm特细砂組(52%)；样砂粒径组成数据符合不同海积沙滩反映不同底质沿岸的假设。推测涠洲岛三样区的微型腹足贝类物种丰富度差异与海岸底质环境因素有关系；提出保护海岸底栖环境，是保护涠洲岛微型贝类物种多样性首要之务。

Abstract: In order to explore the current status of the communities of extant microgastropod mollusks among different types of the coast of Weizhou Island, China, three search areas i.e., the North Shell Beach, East Hengling Beach and Nanwan Beach were selected for micro shellfish species investigation based on the geomorphologic types. Six, five and six bags (about 1000 grams each) of sediment samples were collected, respectively, at the same interval along the supratidal zone. After sieving, micromollusks were taken and the ten most representative species were analyzed. The results showed that all 2704 empty shells of micromollusks were collected from the three study areas and the Cerithiidae fauna (37.1%) was the most abundant. The species richness is in the Shell Beach area > Hengling Beach area > Nanwan Beach area. Especially the two species of Pandalosia subulata and Pseudodaphnella caelata, which are widely distributed in the Shell Beach area and the east coast beach area, have not been harvested in Nanwan Beach area. From the distribution of substrate texture, the particle size is larger in the Shell Beach, about 0.43 mm (42%), than in the Hengling Beach 0.126~0.25 mm (48%) and Nanwan Beach 0.067~0.125 mm (52%). The data supports the hypothesis that different beach deposits reflect different coastal sediments. It is speculated that species distribution is related to coastal sedimentary factors among areas, and the protection of the benthic environment is beneficial to the protection of micromol-lusks species diversity in Weizhou Island.