Long‐term warming destabilizes aquatic ecosystems through weakening biodiversity‐mediated causal networks. (20th September 2020)

• Record Type: Journal Article
• Authors: Chang, Chun‐Wei; Ye, Hao; Miki, Takeshi; Deyle, Ethan R.; Souissi, Sami; Anneville, Orlane; Adrian, Rita; Chiang, Yin‐Ru; Ichise, Satoshi; Kumagai, Michio; Matsuzaki, Shin‐ichiro S.; Shiah, Fuh‐Kwo; Wu, Jiunn‐Tzong; Hsieh, Chih‐hao; Sugihara, George
• Is Part Of: Global change biology. Volume 26:Number 11(2020)
• Page Start: 6413
• Page End: 6423
• Publication Date: 2020-09-20
• Subjects: biodiversity–ecosystem functioning -- causal network -- phytoplankton -- stability -- warming; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.15323
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Understanding how ecosystems will respond to climate changes requires unravelling the network of functional responses and feedbacks among biodiversity, physicochemical environments, and productivity. These ecosystem components not only change over time but also interact with each other. Therefore, investigation of individual relationships may give limited insights into their interdependencies and limit ability to predict future ecosystem states. We address this problem by analyzing long‐term (16–39 years) time series data from 10 aquatic ecosystems and using convergent cross mapping (CCM) to quantify the causal networks linking phytoplankton species richness, biomass, and physicochemical factors. We determined that individual quantities (e.g., total species richness or nutrients) were not significant predictors of ecosystem stability (quantified as long‐term fluctuation of phytoplankton biomass); rather, the integrated causal pathway in the ecosystem network, composed of the interactions among species richness, nutrient cycling, and phytoplankton biomass, was the best predictor of stability. Furthermore, systems that experienced stronger warming over time had both weakened causal interactions and larger fluctuations. Thus, rather than thinking in terms of separate factors, a more holistic network view, that causally links species richness and the other ecosystem components, is required to understand and predict climate impacts on the temporal stability of aquatic ecosystems. Abstract : A cross‐system study analyzing long‐term time series data collected from 10 aquatic ecosystems revealed novel mechanisms explaining how warming destabilized the dynamics of ecosystem functioning (e.g., phytoplankton biomass). The core analysis centred on empirically quantifying causal relationships between the big‐picture ecosystem variables: diversity, nutrient cycling, phytoplankton biomass and others. Systems experiencing stronger long‐term warming had weakened diversity‐mediated regulatory pathways, and the weakened regulatory pathways made ecosystems less stable. The findings, for the first time, emphasize the importance of a holistic network view of ecosystems, indicating that integrated regulatory pathways, instead of individual variables or interactions, best predict ecosystem stability.