Happe Anika, Meijer Kasper J, Dajka Jan-Claas, Franken Oscar, Haslob Holger, Govers Laura L, Kleyer Michael, Kok Annebelle C M, Kuczynski Lucie, Lõhmus Kertu, van der Meij Sancia E T, Olff Han, Rönn Lena, Ryabov Alexey, Sell Anne F, Thieltges David W, Eriksson Britas Klemens, Hillebrand Helmut
Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany.
Groningen Institute for Evolutionary Life-Sciences, University of Groningen, Groningen, AG, the Netherlands.
Glob Chang Biol. 2025 Jun;31(6):e70298. doi: 10.1111/gcb.70298.
Many monitoring programs aim to understand regional biodiversity patterns in relation to global and regional conservation targets, using either community-wide biodiversity metrics to describe the community status or trends of pre-selected "key" species as biodiversity change indicators. However, the former often lacks information on which species are changing, and the latter is heavily skewed towards specific taxa, potentially overlooking changes in other, functionally important taxa. We gathered an extensive set of monitoring data with over 3000 population trends (ranging from 5 to 91 years in duration) for a wide range of taxa across the Wadden Sea. We combined a systematic and quantitative categorization of population trends (weighted vote count) with a meta-analysis on different taxonomic levels. This allowed the first cross-taxa synopsis of species declines and increases and determined their directionalities throughout time. Our meta-analysis showed an overall decrease in population size for fish, zooplankton, and plant species, while birds showed an overall increase. However, these increases mask recent negative trends within specific bird groups since the late 1990s. In contrast, fish populations exhibited declines over the entire monitoring period. Species with declining populations (losers) were phylogenetically related, whereas species with increasing populations (winners) represented various organismal groups. Directionality and onsets of change in population trends were temporally synchronized throughout several groups, such as bivalves, fish, and birds, and may provide warning signals for future local extinctions in these taxa. Our analysis moves beyond typical indicator species by including the entire species inventory of the system. Basal trophic levels of aquatic ecosystems, such as zooplankton and phytoplankton, are often missing from policy assessments but are among the most important organism groups for ecosystem functioning. Here, we show that without additional monitoring effort, a systematic analysis of population trends adds to our understanding of trophic and compositional restructuring of ecosystems.
许多监测项目旨在了解区域生物多样性模式与全球和区域保护目标的关系，要么使用全群落生物多样性指标来描述群落状况，要么将预先选定的“关键”物种的趋势作为生物多样性变化指标。然而，前者往往缺乏有关哪些物种正在发生变化的信息，而后者则严重偏向特定的分类群，可能会忽略其他功能重要分类群的变化。我们收集了大量监测数据，涵盖了瓦登海广泛分类群的3000多个种群趋势（持续时间从5年到91年不等）。我们将种群趋势的系统定量分类（加权投票计数）与不同分类水平的荟萃分析相结合。这使得首次能够对物种的减少和增加进行跨分类群概述，并确定它们随时间的变化方向。我们的荟萃分析表明，鱼类、浮游动物和植物物种的种群规模总体下降，而鸟类总体增加。然而，这些增加掩盖了自20世纪90年代末以来特定鸟类群体近期的负面趋势。相比之下，鱼类种群在整个监测期内都呈下降趋势。种群数量下降的物种（失败者）在系统发育上相关，而种群数量增加的物种（胜利者）代表了不同的生物群体。几个群体（如双壳类、鱼类和鸟类）的种群趋势变化方向和起始时间在时间上是同步的，这可能为这些分类群未来的局部灭绝提供预警信号。我们的分析超越了典型的指示物种，纳入了系统的整个物种清单。水生生态系统的基础营养级，如浮游动物和浮游植物，在政策评估中常常缺失，但它们是对生态系统功能最重要的生物群体之一。在这里，我们表明，无需额外的监测工作，对种群趋势的系统分析就能增进我们对生态系统营养和组成结构重组的理解。
