Grupo de Ecologia Bentônica, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil.
Marítima Estudos Bênticos, Laguna, Santa Catarina, Brazil.
PeerJ. 2024 Jul 12;12:e17727. doi: 10.7717/peerj.17727. eCollection 2024.
Sandy beaches are dynamic environments housing a large diversity of organisms and providing important environmental services. Meiofaunal metazoan are small organisms that play a key role in the sediment. Their diversity, distribution and composition are driven by sedimentary and oceanographic parameters. Understanding the diversity patterns of marine meiofauna is critical in a changing world.
In this study, we investigate if there is seasonal difference in meiofaunal assemblage composition and diversity along 1 year and if the marine seascapes dynamics (water masses with particular biogeochemical features, characterized by temperature, salinity, absolute dynamic topography, chromophoric dissolved organic material, chlorophyll-a, and normalized fluorescent line height), rainfall, and sediment parameters (total organic matter, carbonate, carbohydrate, protein, lipids, protein-to-carbohydrate, carbohydrate-to-lipids, and biopolymeric carbon) affect significatively meiofaunal diversity at a tropical sandy beach. We tested two hypotheses here: (i) meiofaunal diversity is higher during warmer months and its composition changes significatively among seasons along a year at a tropical sandy beach, and (ii) meiofaunal diversity metrics are significantly explained by marine seascapes characteristics and sediment parameters. We used metabarcoding (V9 hypervariable region from 18S gene) from sediment samples to assess the meiofaunal assemblage composition and diversity (phylogenetic diversity and Shannon's diversity) over a period of 1 year.
Meiofauna was dominated by Crustacea (46% of sequence reads), Annelida (28% of sequence reads) and Nematoda (12% of sequence reads) in periods of the year with high temperatures (>25 °C), high salinity (>31.5 ppt), and calm waters. Our data support our initial hypotheses revealing a higher meiofaunal diversity (phylogenetic and Shannon's Diversity) and different composition during warmer periods of the year. Meiofaunal diversity was driven by a set of multiple variables, including biological variables (biopolymeric carbon) and organic matter quality (protein content, lipid content, and carbohydrate-to-lipid ratio).
沙滩是动态环境，拥有丰富多样的生物，提供重要的环境服务。小型后生动物是在沉积物中起关键作用的小型生物。它们的多样性、分布和组成受沉积物和海洋学参数的驱动。了解海洋小型后生动物的多样性模式在变化的世界中至关重要。
在这项研究中，我们调查了在一年中，小型后生动物组合组成和多样性是否存在季节性差异，以及海洋景观动态（具有特定生物地球化学特征的水团，其特征为温度、盐度、绝对动态地形、色素溶解有机物、叶绿素-a 和归一化荧光线高）、降雨量和沉积物参数（总有机物质、碳酸盐、碳水化合物、蛋白质、脂质、蛋白质-碳水化合物、碳水化合物-脂质和生物聚合碳）是否显著影响热带沙滩上的小型后生动物多样性。我们在这里检验了两个假设：（i）在温暖的月份，小型后生动物的多样性更高，并且在一年中的不同季节中，其组成会发生显著变化；（ii）小型后生动物多样性指标由海洋景观特征和沉积物参数显著解释。我们使用沉积物样本中的 metabarcoding（18S 基因的 V9 高变区）来评估一年中不同时期的小型后生动物组合组成和多样性（系统发育多样性和香农多样性）。
在一年中温度较高（>25°C）、盐度较高（>31.5 ppt）和水流平静的时期，小型后生动物主要由甲壳类动物（46%的序列读数）、环节动物（28%的序列读数）和线虫（12%的序列读数）组成。我们的数据支持我们的初始假设，即揭示了在一年中温暖时期更高的小型后生动物多样性（系统发育和香农多样性）和不同的组成。小型后生动物多样性由一组多个变量驱动，包括生物变量（生物聚合碳）和有机质质量（蛋白质含量、脂质含量和碳水化合物-脂质比）。
