Causal feedback loops modify lake chlorophyll a–nutrient relationships over two decades of nutrient reductions and climate warming

IF 3.8 1区 地球科学 Q1 LIMNOLOGY
Hui Fu, Korhan Özkan, Liselotte Sander Johansson, Martin Søndergaard, Torben Linding Lauridsen, Guixiang Yuan, Erik Jeppesen
{"title":"Causal feedback loops modify lake chlorophyll a–nutrient relationships over two decades of nutrient reductions and climate warming","authors":"Hui Fu,&nbsp;Korhan Özkan,&nbsp;Liselotte Sander Johansson,&nbsp;Martin Søndergaard,&nbsp;Torben Linding Lauridsen,&nbsp;Guixiang Yuan,&nbsp;Erik Jeppesen","doi":"10.1002/lno.12667","DOIUrl":null,"url":null,"abstract":"<p>Understanding how the causal feedback between phytoplankton and environmental drivers controlling the chlorophyll <i>a</i> (Chl <i>a</i>, as a proxy of phytoplankton biomass)–nutrient relationships are modulated under different ecosystem conditions is a major challenge in aquatic ecology. Using an empirical dynamic model (convergent cross mapping) on a 20-yr dataset on 20 Danish lakes, we quantified hypothesized causal feedback networks for each lake and related them to lake system properties (e.g., mean water depth, nutrient concentrations and extent of reduction, climate warming) vs. the Chl <i>a</i>–nutrient relationship (estimated from generalized least square models). The results showed prevalent causal feedback across the studied lakes, which demonstrated clear patterns for the tested ecosystem variations. Weaker causal feedbacks were found in deeper lakes and lakes with larger warming trends, while stronger causal feedbacks appeared in lakes experiencing greater reductions of TP (total phosphorus) and TN (total nitrogen). Moreover, these causal feedbacks showed a strong and positive coupled pattern. Most of the causal feedbacks worked as enhancement loops, which promote the sensitivity of phytoplankton to TP, not least in shallow lakes with a high TP reduction, and as regulatory loops, which force a shift in the Chl <i>a</i>–TN relationship from a more negative slope in lakes experiencing a high nutrient reduction and weak warming to a positive slope in lakes with low nutrient reduction and stronger warming. Our findings suggest a mechanistic explanation of how internal feedbacks regulate the Chl <i>a</i>–nutrient relationships across a broad gradient of nutrient reductions, climate warming, and lake morphologies.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":null,"pages":null},"PeriodicalIF":3.8000,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Limnology and Oceanography","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/lno.12667","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"LIMNOLOGY","Score":null,"Total":0}
引用次数: 0

Abstract

Understanding how the causal feedback between phytoplankton and environmental drivers controlling the chlorophyll a (Chl a, as a proxy of phytoplankton biomass)–nutrient relationships are modulated under different ecosystem conditions is a major challenge in aquatic ecology. Using an empirical dynamic model (convergent cross mapping) on a 20-yr dataset on 20 Danish lakes, we quantified hypothesized causal feedback networks for each lake and related them to lake system properties (e.g., mean water depth, nutrient concentrations and extent of reduction, climate warming) vs. the Chl a–nutrient relationship (estimated from generalized least square models). The results showed prevalent causal feedback across the studied lakes, which demonstrated clear patterns for the tested ecosystem variations. Weaker causal feedbacks were found in deeper lakes and lakes with larger warming trends, while stronger causal feedbacks appeared in lakes experiencing greater reductions of TP (total phosphorus) and TN (total nitrogen). Moreover, these causal feedbacks showed a strong and positive coupled pattern. Most of the causal feedbacks worked as enhancement loops, which promote the sensitivity of phytoplankton to TP, not least in shallow lakes with a high TP reduction, and as regulatory loops, which force a shift in the Chl a–TN relationship from a more negative slope in lakes experiencing a high nutrient reduction and weak warming to a positive slope in lakes with low nutrient reduction and stronger warming. Our findings suggest a mechanistic explanation of how internal feedbacks regulate the Chl a–nutrient relationships across a broad gradient of nutrient reductions, climate warming, and lake morphologies.

因果反馈回路改变了二十年来营养物质减少和气候变暖与湖泊叶绿素 a-营养物质之间的关系
在不同的生态系统条件下,浮游植物与控制叶绿素 a(Chl a,浮游植物生物量的代表)- 营养物质关系的环境驱动因素之间的因果反馈如何调节,这是水生生态学面临的一大挑战。我们在 20 个丹麦湖泊的 20 年数据集上使用经验动态模型(会聚交叉映射),量化了每个湖泊的假设因果反馈网络,并将其与湖泊系统属性(如平均水深、营养物浓度和减少程度、气候变暖)以及 Chl a 营养物关系(通过广义最小二乘法模型估算)联系起来。研究结果表明,在所研究的湖泊中普遍存在因果反馈,这表明所测试的生态系统变化具有清晰的模式。在较深的湖泊和变暖趋势较大的湖泊中,因果反馈较弱,而在 TP(总磷)和 TN(总氮)减少较多的湖泊中,因果反馈较强。此外,这些因果反馈呈现出强烈的正耦合模式。大多数因果反馈是作为增强环路和调节环路起作用的,前者促进了浮游植物对 TP 的敏感性,尤其是在 TP 减少较多的浅水湖泊中;后者迫使 Chl a-TN 关系从营养物质减少较多、气候变暖较弱的湖泊中的负斜率转变为营养物质减少较少、气候变暖较强的湖泊中的正斜率。我们的研究结果从机理上解释了内部反馈是如何调节营养盐减少、气候变暖和湖泊形态的广泛梯度上的 Chl a 营养盐关系的。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
Limnology and Oceanography
Limnology and Oceanography 地学-海洋学
CiteScore
8.80
自引率
6.70%
发文量
254
审稿时长
3 months
期刊介绍: Limnology and Oceanography (L&O; print ISSN 0024-3590, online ISSN 1939-5590) publishes original articles, including scholarly reviews, about all aspects of limnology and oceanography. The journal''s unifying theme is the understanding of aquatic systems. Submissions are judged on the originality of their data, interpretations, and ideas, and on the degree to which they can be generalized beyond the particular aquatic system examined. Laboratory and modeling studies must demonstrate relevance to field environments; typically this means that they are bolstered by substantial "real-world" data. Few purely theoretical or purely empirical papers are accepted for review.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信