Biological soil crusts (hereafter, biocrusts) are communities of microorganisms that regulate key ecosystem processes such as water distribution, soil erosion, and nutrient cycling in drylands worldwide. The nature of biocrust function can be influenced by multiple environmental factors, including climatic conditions (for example, precipitation), interactions with plants, and anthropogenic disturbances. Animal regulation of biocrust function has received less research attention, focusing primarily on livestock trampling and to a much lesser extent on biocrust consumption by mesofauna. Deposition of animal waste products, carcasses, and other body secretions such as mucus may also affect biocrust function. Yet, this novel regulatory pathway, to our knowledge, has never been empirically tested. Our goal was to begin bridging this knowledge gap by exploring how snail mucus affects biocrust CO₂ efflux—using two distinct biocrust communities and three snail species. We found that snail mucus increased the CO₂ efflux of both cyanobacteria-dominated and lichen/moss-dominated biocrusts. However, the magnitude of snail mucus effects on biocrust CO₂ efflux varied between snail species—possibly due to species-level differences in snail diet. Our study highlights a novel interaction between animals and biocrusts and suggests that even small quantities of animal-derived nutrients can have important consequences for biocrust carbon dynamics.

生物土壤结皮（以下简称生物结皮）是调节关键生态系统过程的微生物群落，例如全球旱地的水分布、土壤侵蚀和养分循环。生物地壳功能的性质可能受到多种环境因素的影响，包括气候条件（例如降水）、与植物的相互作用和人为干扰。动物对生物地壳功能的调节受到的研究较少，主要集中在牲畜践踏上，在较小程度上关注中型动物对生物地壳的消耗。动物排泄物、尸体和其他身体分泌物（如粘液）的沉积也可能影响生物外壳的功能。然而，据我们所知，这种新的监管途径从未经过实证检验。₂流出——使用两个不同的生物外壳群落和三个蜗牛物种。我们发现蜗牛粘液增加了以蓝藻为主的和以地衣/苔藓为主的生物结皮的 CO ₂流出。然而，蜗牛粘液对生物外壳 CO ₂流出的影响程度因蜗牛物种而异——可能是由于蜗牛饮食的物种水平差异。我们的研究强调了动物和生物结皮之间的一种新的相互作用，并表明即使是少量的动物源性营养素也会对生物结皮碳动力学产生重要影响。