Glaciers support diverse ecosystems that are largely comprised of microbial life. However, at larger, macroscopic scales, glacier moss balls (sometimes called “glacier mice”) can develop from impurities on ice surfaces and represent a relatively rare biological phenomenon. These ovoid-shaped conglomerations of dirt and moss are only found on some glacier surfaces and provide key habitats for invertebrate colonization. Yet, despite their development and presence being widely reported, no studies of their movement and persistence across years have been conducted. This knowledge gap is particularly important when considering the degree to which glacier moss balls may represent viable, long-term biotic habitats on glaciers, perhaps complete with their own ecological succession dynamics. Here, we describe the movement and persistence of glacier moss balls on the Root Glacier in southcentral Alaska, USA. We show that glacier moss balls move an average of 2.5 cm per day in herd-like fashion initially to the south and later towards the southwest, and their movements are positively correlated with glacier ablation. Surprisingly, the dominant moss ball movement direction does not align with the prevailing wind or downslope directions, nor with the dominant direction of solar radiation. After attaining a mature size, glacier moss balls persist for many years, likely in excess of 6 years. Finally, we observed moss ball formation on the Root Glacier to occur within a narrow, low albedo stripe downwind of a nunatak, a potential key source of moss spores and/or fine-grained sediment that interact to promote their formation.

中文翻译：

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滚石聚集苔藓：阿拉斯加冰川上苔藓球的运动和寿命

冰川支持着主要由微生物生命组成的多样化生态系统。然而，在更大的宏观尺度上，冰川苔藓球（有时称为“冰川老鼠”）可以从冰面上的杂质中发育出来，代表一种相对罕见的生物现象。这些由泥土和苔藓组成的卵形聚集体仅存在于某些冰川表面，为无脊椎动物定居提供了重要的栖息地。然而，尽管它们的发展和存在被广泛报道，但没有对其多年来的运动和持久性进行研究。在考虑冰川苔藓球可能代表冰川上可行的长期生物栖息地的程度时，这种知识差距尤为重要，可能还具有它们自己的生态演替动态。这里，我们描述了美国阿拉斯加中南部根冰川上冰川苔藓球的运动和持久性。我们表明，冰川苔藓球每天平均以成群的方式向南移动 2.5 厘米，然后向西南移动，它们的移动与冰川消融呈正相关。令人惊讶的是，主要的苔藓球运动方向与盛行风或下坡方向不一致，也不与太阳辐射的主要方向一致。在达到成熟的大小后，冰川苔藓球会持续多年，可能超过 6 年。最后，我们观察到根冰川上的苔藓球形成发生在 nunatak 下风处的狭窄、低反照率条纹内，这是苔藓孢子和/或细粒沉积物的潜在关键来源，它们相互作用以促进它们的形成。