Number of microplastic particles on periwinkle pedal mucus in experimental setups@en

The rapid dissemination of microplastics in many habitats of the oceans has raised concerns about the consequences for marine biota and ecosystems. Many adverse effects of microplastics on marine invertebrates are consequences of ingestion. Accordingly, the identification of mechanisms that facilitate the uptake of microplastics is essential for the evaluation of possible implications for marine organisms and food webs. Gastropods produce mucus for locomotion. Gastropod pedal mucus naturally retains formerly suspended micro-organisms, such as bacteria, microalgae, and seaweed spores. The retained organisms are consumed by gastropods that forage on pedal mucus. Here, we investigated the potential of gastropod pedal mucus to retain suspended microplastic particles and make them available for ingestion by periwinkles that forage on the contaminated mucus. In laboratory experiments, mucus of the periwinkles Littorina littorea and Littorina obtusata efficiently retained microplastics. Retention of microplastics varied between mucus from conspecifics of different size but not between mucus from either species. The density of microplastics in mucus trails increased concomitantly with the experimental particle concentration but was independent of incubation time. Aging of mucus and, particularly, desiccation affected the retention of microplastics. Periwinkles ingested microplastics when foraging on the contaminated mucus. Our results reveal a functional link between biogenic accumulation of microplastics and their trophic transfer by marine benthic herbivores into marine food webs.

微塑料在全球诸多海洋生境中的快速扩散，已引发学界对其给海洋生物群与海洋生态系统造成潜在影响的广泛担忧。微塑料对海洋无脊椎动物的诸多负面影响，均源于生物对其的摄食过程。因此，明确促进微塑料被生物摄取的相关机制，对评估其对海洋生物与食物网的潜在影响至关重要。腹足类（Gastropods）可分泌足黏液以完成运动，其足黏液能够自然吸附此前处于悬浮状态的微生物，包括细菌、微藻与海藻孢子；这些被吸附的微生物，会被在足黏液表面觅食的腹足类摄食。本研究探讨了腹足足黏液吸附悬浮微塑料颗粒的能力，以及该过程是否会使微塑料可被在受污染黏液表面觅食的滨螺（periwinkles）摄取。实验室实验结果显示，滨螺（Littorina littorea与Littorina obtusata）分泌的足黏液可高效吸附微塑料；不同体型同种滨螺分泌的黏液，其微塑料吸附能力存在差异，但不同滨螺物种间的黏液吸附能力并无显著区别。黏液轨迹中的微塑料密度，随实验设置的颗粒浓度升高而同步上升，但与孵育时长无关；黏液老化，尤其是脱水干燥过程，会对微塑料的吸附效果产生影响；当滨螺在受污染的足黏液表面觅食时，会摄入其中附着的微塑料。本研究结果揭示了微塑料的生物源性积累，与海洋底栖植食性动物介导的微塑料营养级传递进入海洋食物网之间的功能关联。