Data from: Daphniid zooplankton assemblage shifts in response to eutrophication and metal contamination during the Anthropocene

Human activities during the Anthropocene result in habitat degradation that has been associated with biodiversity loss and taxonomic homogenization of ecological communities. Here we estimated effects of eutrophication and heavy metal contamination, separately and in combination, in explaining zooplankton species composition during the past 125–145 years using analysis of daphniid diapausing egg banks from four lakes in the northeastern USA. We then examined how these community shifts influenced patterns of diversity and homogenization. Analysis of past lake production (via subfossil pigments) and metal contamination (via sedimentary metals) demonstrated that eutrophication alone (19–39%) and in combination with metal pollution (17–54%) explained 36–79% of historical variation in daphniid species relative abundances in heavily fertilized lakes. In contrast, metal pollution alone explained the majority (72%) of historical variation in daphniid assemblages at the oligotrophic site. Several species colonization events in eutrophying lakes resulted in increased species richness and gamma diversity through time. At the same time, daphniid assemblages in three eutrophied lakes became more similar to each other (homogenized), but this pattern was only seen when accounting for species presence/absence. We did not observe consistent patterns of divergence between the assemblages in the eutrophying lakes and the low-nutrient reference site. Given the pervasive nature of fertilization and metal pollution, and the sensitivity of cladocerans to these factors, we suggest that many inhabited lake districts may already exhibit similar patterns of daphniid assemblage shifts.人类世（Anthropocene）时期的人类活动会引发生境退化，而生境退化与生物多样性丧失以及生态群落的分类学同质化密切相关。本研究通过对美国东北部四座湖泊的溞类（daphniid）滞育卵库进行分析，估算了过去125至145年间，富营养化、重金属污染单独及联合作用对浮游动物（zooplankton）物种组成的影响。随后，我们探究了这些群落转变如何作用于多样性格局与同质化过程。针对湖泊古生产力（通过亚化石色素检测）与重金属污染（通过沉积金属检测）的分析结果显示：在重度施肥的湖泊中，单独的富营养化（解释贡献率为19%–39%）以及其与金属污染的联合作用（解释贡献率为17%–54%），共同解释了溞类物种相对丰度历史变异的36%–79%。与之形成对照的是，在贫营养参考位点，仅金属污染便解释了溞类群落历史变异的绝大多数（72%）。富营养化湖泊中发生的多次物种定居事件，随时间推移提升了物种丰富度与伽马多样性（gamma diversity）。与此同时，三座富营养化湖泊内的溞类群落彼此间相似度显著提升（即出现分类学同质化），但该模式仅在纳入物种存在/缺失数据时才会显现。我们并未观测到富营养化湖泊与低营养参考位点的群落间存在一致的分化格局。鉴于施肥与金属污染的普遍存在，以及枝角类（cladocerans）对上述扰动因素的敏感性，我们认为，全球诸多已开发湖区或许已呈现出类似的溞类群落转变模式。