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）时期的人类活动引发生境退化，该过程与生物多样性丧失及生态群落的分类学同质化紧密相关。本研究通过分析美国东北部四座湖泊的溞科（Daphniidae）滞育卵库，估算了富营养化与重金属污染各自及联合作用对过去125至145年间浮游动物（zooplankton）物种组成的解释效力。随后我们探究了这些群落转变如何影响生物多样性与同质化格局。通过亚化石色素分析重建湖泊历史初级生产力，结合沉积金属分析重金属污染程度，研究结果显示：在施肥严重的湖泊中，仅富营养化（解释力19%–39%）以及富营养化与重金属污染联合作用（解释力17%–54%）共可解释溞科物种相对丰度历史变异的36%–79%。与之相对，在贫营养样点中，仅重金属污染便可解释溞科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殖事件，随时间推移提升了物种丰富度与γ多样性（gamma diversity）。与此同时，三座富营养化湖泊的溞科群落彼此间相似度显著提升（即发生同质化），但该模式仅在纳入物种存在/缺失数据后方可被观测到。我们未观测到富营养化湖泊与低营养参考样点的群落间存在一致的分化模式。鉴于施肥与重金属污染的普遍分布性，以及枝角类（Cladocera）对这些环境因子的敏感性，我们推测全球诸多已开发湖区或许已出现类似的溞科群落变化模式。