Abstract：
Although evidence suggests the ubiquity of meso- and microplastics (MMPs) in mangrove forests, our knowledge of their bioavailability and risk on mangrove leaves is scarce. Here, we investigated MMP contamination concerning submerged mangrove leaves and herbivorous snails that mainly feed on them from the four mangrove forests located in Beibu Gulf, Guangxi Province, China. Results showed that the MMP abundance on the mangrove leaves ranged from 0.01 ± 0.00 to 0.42 ± 0.15 items cm-2, while it ranged from 0.33 ± 0.21 to 6.20 ± 2.91 items individual-1 in the snails. There were significant positive correlations between snails and leaves regarding the abundance of total MMPs and the proportions of MMPs with the same characteristics. Expanded polystyrene (EPS) that mainly derived from aquaculture rafts, accounted for a major component both on the leaves and in the snails in Shi Jiao (SJ). Both the detection frequency and percentage of larger EPS (2.00-17.50 mm) on the leaves in SJ were higher than other sites. Meanwhile, the detection frequency, abundance and percentage of larger EPS on the leaves had significant positive correlations with those of micro-EPS in the snails. These findings suggested that mangrove leaves may represent a viable pathway for MMPs to enter the herbivorous snails. Larger EPS with higher frequency of occurrence on mangrove leaves were more likely to be encountered and ingested by snail considering its opportunistic feeding behavior. In addition, 11 sensitive genes involved in the processes of metabolism, intestinal mucosal immune systems, and cellular transduction in the snails were significantly suppressed by MMP exposure, which may be potentially used as early biomarkers to indicate the biological effects of MMPs under realistic environmental conditions. Overall, this study provides novel insights into the fate, sources, and biological effects of MMPs on mangrove leaves.
摘要：
尽管有证据表明，在红树林中普遍存在中观塑料和微塑料（MMPs），我们对它们在红树林叶上的生物利用度和风险的了解很少。这里,我们调查了与淹没的红树林叶和草食蜗牛有关的MMP污染，这些蜗牛主要以位于北部湾的四个红树林为食，广西,中国。结果表明，红树林叶片上的MMP丰度范围为0.01±0.00至0.42±0.15项cm-2，而蜗牛中的MMP丰度范围为0.33±0.21至6.20±2.91项。蜗牛和叶子之间在总MMPs的丰度和具有相同特征的MMPs的比例方面存在显着正相关。发泡聚苯乙烯（EPS），主要来自水产养殖筏，在石角（SJ）的叶子和蜗牛中都占主要成分。SJ叶片上较大EPS（2.00-17.50mm）的检测频率和百分比均高于其他部位。同时,检测频率,叶片上较大EPS的丰度和百分比与蜗牛中微小EPS的含量呈显着正相关。这些发现表明，红树林的叶子可能是MMPs进入草食蜗牛的可行途径。考虑到蜗牛的机会摄食行为，红树林叶片上发生频率较高的较大EPS更容易遇到和摄入。此外,涉及代谢过程的11个敏感基因，肠道粘膜免疫系统，MMP暴露显著抑制了蜗牛的细胞转导，这可能是潜在的早期生物标志物，以指示MMPs在现实环境条件下的生物学效应。总的来说,这项研究提供了对命运的新颖见解，来源,MMPs对红树林叶片的生物学效应。
