Huang Hailong, Chen Sentao, Xu Zhihui, Wu Yanhua, Mei Limin, Pan Yuanbo, Yan Xiaojun, Zhou Chengxu
School of Marine Science, Ningbo University, Ningbo, Zhejiang 315211, China.
College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang 315211, China.
Mar Pollut Bull. 2023 Feb;187:114556. doi: 10.1016/j.marpolbul.2022.114556. Epub 2023 Jan 12.
Filter-feeder bivalves and phytoplankton are interdependent. Their interaction plays important role in estuarine and coastal ecosystem. The correlation between bivalve feeding and phytoplankton is highly species specificity and environment dependent. In the background of miniature and nondiatom trend of phytoplankton in coastal seawaters, how bivalve respond and how the response play roles in the phytoplankton community are poorly known. In the present study, by applying DNA metabarcoding approach based on plastid 23S rDNA, this question was addressed by comparing the phytoplankton composition in the seston and the stomach content of blood clam Tegillarca granosa sampled during the growth period from March to November 2020 in an experimental farm on tidal flat in Xiangshan Bay, East China Sea. The result showed that, a total of seven phyla, 55 genera and 73 species of phytoplankton were identified for all samples. Chlorophyta, Bacillariophyta, and Cyanobacteria were found to be three dominant phyla both in the stomach contents and seston. High diversity of pico-sized phytoplankton, which was easy overlooked by microscopy, was revealed both in seston and stomach contents. This result indicated that the clam was able to feed on the pico-sized algae. At the genus level, the most abundant genera were the pico-sized green alga Ostreococcus (6.12 %-67.88 %) in seston and Picochlorum (4.07 %-35.33 %) in the stomach contents. In addition, microalgae of high nutritional value showed trend of higher proportion in stomach contents than that in seston, especially in July and September when significant growth of T. granosa was observed during this period (the body size increased 155 %). Biodiversity of phytoplankton in the seston was totally higher than that in stomach content, however, the changes among the months showed respective trend. Especially in July when the biodiversity was the lowest in seston, that in the stomach content showed the highest. The results indicated that blood clam farming might influence the phytoplankton composition, including those of pico-sized level, although the particular species in seston were mainly correlating with the dominant environmental factors such as temperature, salinity, pH respectively. These results extend the understanding of roles that bivalve aquaculture may play in the changing of coastal phytoplankton community.
滤食性双壳贝类与浮游植物相互依存。它们的相互作用在河口和沿海生态系统中起着重要作用。双壳贝类摄食与浮游植物之间的相关性具有高度的物种特异性且依赖于环境。在沿海水域浮游植物呈现小型化和非硅藻化趋势的背景下，双壳贝类如何做出反应以及这种反应如何在浮游植物群落中发挥作用尚不清楚。在本研究中，通过应用基于质体23S rDNA的DNA宏条形码方法，对2020年3月至11月生长期间在中国东海象山湾潮间带实验养殖场采集的缢蛏的悬浮颗粒和胃含物中的浮游植物组成进行比较，从而解决了这个问题。结果表明，所有样本共鉴定出7个门、55个属和73种浮游植物。绿藻门、硅藻门和蓝细菌门在胃含物和悬浮颗粒中均为三个优势门类。在悬浮颗粒和胃含物中均发现了容易被显微镜忽视的微型浮游植物的高多样性。这一结果表明缢蛏能够摄食微型藻类。在属水平上, 悬浮颗粒中最丰富的属是微型绿藻奥氏藻 (6.12% - 67.88%)，胃含物中是皮果藻属 (4.07% - 35.33%)。此外，营养值高的微藻在胃含物中的比例呈现出高于悬浮颗粒中的趋势，尤其是在7月和9月，在此期间观察到缢蛏显著生长 (体长增加了155%)。悬浮颗粒中浮游植物的生物多样性总体上高于胃含物中的，但各月份间的变化呈现出各自的趋势。特别是在7月，悬浮颗粒中的生物多样性最低，而胃含物中的生物多样性最高。结果表明，缢蛏养殖可能会影响浮游植物的组成，包括微型水平的浮游植物，尽管悬浮颗粒中的特定物种主要分别与温度、盐度、pH等主要环境因素相关。这些结果扩展了对双壳贝类养殖在沿海浮游植物群落变化中可能发挥的作用的认识。
