Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, SE-750-07 Uppsala, Sweden.
Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, SE-750-07 Uppsala, Sweden.
Sci Total Environ. 2020 Dec 1;746:141110. doi: 10.1016/j.scitotenv.2020.141110. Epub 2020 Jul 22.
The use of discontinuity analysis to assess resilience and alternative regimes of ecosystems has mostly been based on animal size. We so far lack systematic comparisons of size-based and abundance-based approaches necessary for assessing the performance and suitability of the discontinuity analysis across a broader range of organism groups. We used an outdoor mesocosm setup to mimic shallow lake ecosystems with different depths (1.2 m deep, "shallow"; 2.2 m deep, "deep") and trophic status (i.e. low and high nutrient status characteristic of mesotrophic and hypertrophic lakes, respectively). We compared resilience assessments, based on four indicators (cross-scale structure, within-scale structure, aggregation length and gap size) inferred from the size and abundance (biovolume) structure of phytoplankton communities. Our results indicate that resilience assessments based on size and biovolume were largely comparable, which is likely related to similar variability in the size and abundance of phytoplankton as a function of nutrient concentrations. Also, nutrient enrichment rather than water depth influenced resilience, manifested in decreased cross-scale structure and increased aggregation lengths and gap sizes in the high-nutrient treatment. These resilience patterns coupled with decreased phytoplankton diversity and dominance of cyanobacteria in the high nutrient treatment support the use of discontinuity analysis for testing alternative regimes theory. Concordance of size-based and abundance-based results highlights the approach as being potentially robust to infer resilience in organism groups that lack discrete size structures.
利用不连续性分析来评估生态系统的弹性和替代状态，主要基于动物的体型。我们目前缺乏系统的比较，无法评估在更广泛的生物群体中，基于体型和基于丰度的方法的性能和适用性。我们使用户外中观模型设置来模拟具有不同水深（1.2 米深，“浅”；2.2 米深，“深”）和营养状态（即中营养和富营养湖泊特征的低和高营养状态）的浅水湖泊生态系统。我们比较了基于浮游植物群落大小和丰度（生物量）结构推断出的四个指标（跨尺度结构、尺度内结构、聚集长度和间隙大小）的弹性评估。我们的结果表明，基于大小和生物量的弹性评估在很大程度上是可比的，这可能与浮游植物大小和丰度随营养浓度的变化具有相似的可变性有关。此外，富营养化而不是水深影响了弹性，表现在高营养处理中跨尺度结构减少和聚集长度增加以及间隙大小增加。这些弹性模式伴随着浮游植物多样性的减少和高营养处理中蓝藻的优势地位，支持了不连续性分析在测试替代状态理论中的应用。基于体型和基于丰度的结果的一致性突出了该方法在缺乏离散体型结构的生物群体中推断弹性的潜在稳健性。
