Spatial identification of critical nutrient loads of large shallow lakes: Implications for Lake Taihu (China)

Janssen, Annette B.G.; Jager, Victor C. L. de; Janse, Jan H.; Kong, Xiangzhen; Liu, Sien; Ye, Qinghua; Mooij, Wolf M.

doi:10.1016/j.watres.2017.04.045

Cited by 116 publications

(96 citation statements)

References 38 publications

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“…In the present study in Meiliang Bay, N and P were determined as the limiting factors in different regions of the Bay, highlighting that both N and P loading reduction are essential for controlling the magnitude and duration of algal blooms in Meiliang Bay. This finding is supported by the results of previous studies (Janssen et al., ; Xu et al., , ).…”

Section: Resultssupporting

confidence: 91%

Nutrient limitation and enzymolysis of phosphorus in Meiliang Bay, Lake Taihu, during algal blooms

Jiang

Zhou

et al. 2019

Water Environment Research

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In this study, algal growth potential tests were performed in water samples collected from six sampling sites in Meiliang Bay, Lake Taihu. The potential release of soluble reactive phosphorus (SRP) by enzymatic hydrolysis of enzymatically hydrolyzable phosphorus (EHP) was simultaneously evaluated. Results show that all studied regions were in highly eutrophic states, with additional nitrogen (N) or phosphorus (P) inputs, inducing negligible further increase in algal growth. EHP in water could be rapidly transformed into SRP, further supporting the proliferation of algal blooms. The shortest EHP mineralization time was calculated as 69 minutes; therefore, limiting specific nutrient inputs alone in extremely eutrophic lakes can have a limited effect on suppressing the proliferation of algal blooms. Methods to establish a suitable environmental fate for excessive nitrogen and phosphorus nutrients may be more effective and provide more significant results. Practitioner points N and P were no longer serving as the limiting factors in Meiliang Bay. Enzymatically hydrolysable phosphorus could be hydrolyzed into soluble reactive phosphorus in a very short period during algal blooms. Both enzymatically hydrolysable phosphorus and soluble reactive phosphorus are required to be curbed in practical eutrophication control.

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Section: Resultssupporting

confidence: 91%

Nutrient limitation and enzymolysis of phosphorus in Meiliang Bay, Lake Taihu, during algal blooms

Jiang

Zhou

et al. 2019

Water Environment Research

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“…Multimodality of state variable distributions and dual relationships between state variables and control factors can be symptoms of alternative stable states, although they do not provide definitive evidence for their existence (Scheffer and Carpenter 2003). Laboratory or field experiments, especially those that fully demonstrate hysteresis, provide more convincing support for alternate attractors (Schr€ oder et al 2005), though the most tractable experiments are small-scale laboratory or mesocosm studies that may not reflect field conditions (Janssen et al 2017). Laboratory or field experiments, especially those that fully demonstrate hysteresis, provide more convincing support for alternate attractors (Schr€ oder et al 2005), though the most tractable experiments are small-scale laboratory or mesocosm studies that may not reflect field conditions (Janssen et al 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Statistical tests exist for diagnosing hysteresis in observational data but require extensive time series containing several transitions (Andersen et al 2009). Laboratory or field experiments, especially those that fully demonstrate hysteresis, provide more convincing support for alternate attractors (Schr€ oder et al 2005), though the most tractable experiments are small-scale laboratory or mesocosm studies that may not reflect field conditions (Janssen et al 2017). Finally, mechanistic models such as PCLake (Janse et al 2008) can be used to infer the existence of alternative stable states, but these models may be quite complex and require extensive parameterization.…”

Section: Discussionmentioning

confidence: 99%

Uncovering state‐dependent relationships in shallow lakes using Bayesian latent variable regression

Vitense

Hanson

Herwig

et al. 2018

Ecological Applications

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Ecosystems sometimes undergo dramatic shifts between contrasting regimes. Shallow lakes, for instance, can transition between two alternative stable states: a clear state dominated by submerged aquatic vegetation and a turbid state dominated by phytoplankton. Theoretical models suggest that critical nutrient thresholds differentiate three lake types: highly resilient clear lakes, lakes that may switch between clear and turbid states following perturbations, and highly resilient turbid lakes. For effective and efficient management of shallow lakes and other systems, managers need tools to identify critical thresholds and state-dependent relationships between driving variables and key system features. Using shallow lakes as a model system for which alternative stable states have been demonstrated, we developed an integrated framework using Bayesian latent variable regression (BLR) to classify lake states, identify critical total phosphorus (TP) thresholds, and estimate steady state relationships between TP and chlorophyll a (chl a) using cross-sectional data. We evaluated the method using data simulated from a stochastic differential equation model and compared its performance to k-means clustering with regression (KMR). We also applied the framework to data comprising 130 shallow lakes. For simulated data sets, BLR had high state classification rates (median/mean accuracy >97%) and accurately estimated TP thresholds and state-dependent TP-chl a relationships. Classification and estimation improved with increasing sample size and decreasing noise levels. Compared to KMR, BLR had higher classification rates and better approximated the TP-chl a steady state relationships and TP thresholds. We fit the BLR model to three different years of empirical shallow lake data, and managers can use the estimated bifurcation diagrams to prioritize lakes for management according to their proximity to thresholds and chance of successful rehabilitation. Our model improves upon previous methods for shallow lakes because it allows classification and regression to occur simultaneously and inform one another, directly estimates TP thresholds and the uncertainty associated with thresholds and state classifications, and enables meaningful constraints to be built into models. The BLR framework is broadly applicable to other ecosystems known to exhibit alternative stable states in which regression can be used to establish relationships between driving variables and state variables.

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“…However, instead, regime shift could be restricted to certain habitats or could occur at different paces, depending on habitats (Janssen et al, 2017;Scheffer & van Nes, 2007;van Nes & Scheffer, 2005). However, instead, regime shift could be restricted to certain habitats or could occur at different paces, depending on habitats (Janssen et al, 2017;Scheffer & van Nes, 2007;van Nes & Scheffer, 2005).…”

Section: Changes In the Littoral Communitymentioning

confidence: 99%

Seeking alternative stable states in a deep lake

et al. 2018

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Hysteresis linked to alternative stable states may explain delays in water quality recovery despite reduced nutrient loadings in shallow lakes. Because deep lakes are assumed to be less prone to critical transitions, similar delays are attributed to the confounding effects of additional environmental disturbances, such as climate warming. Herein, we hypothesised that the lack of evidence of nutrient‐driven alternative stable states in a deep lake arises from the fact that the nutrient threshold that causes the critical transition is lower than the nutrient threshold in shallow lakes. Thereby, it might have been crossed much earlier in the lake history. To test this hypothesis, we focused on the palaeo‐ecological trajectory of Lake Varese, which is a deep, hypereutrophicated peri‐alpine lake undergoing restoration. Proxies for drivers of ecological state (i.e. total phosphorus—TP—through diatoms and pigments) and ecological responses (Cladocera), as well as a repeatable analysis, were used to identify transitions and to distinguish hysteretic delays from those of the ecosystems responding to additional constraints over the past century. Our results suggest spatial heterogeneity in the ecological response. The littoral habitats changed abruptly and prematurely for a low TP threshold, causing a shift that met many criteria of a flickering‐type critical transition. Soon after the littoral shift, a striking increase in the lake phosphorous concentration was recorded and drove the pelagic assemblage towards a new state. This transition was abrupt, and the pelagic communities exhibited limited evidence of recovery; however, we found no evidence of hysteresis. Therefore, the modern ecological trajectory of the pelagic communities is currently driven by climate warming. This detailed analysis allowed us to go beyond the general pattern that links ecological responses to drivers and suggest that a nonlinear transition following eutrophication can take place in a deep lake synchronously with linear transitions. Instead of triggering a new regime shift, climate warming, to which pelagic habitats are more sensitive than littoral ones, has driven the lake further from its safe operating space.

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Spatial identification of critical nutrient loads of large shallow lakes: Implications for Lake Taihu (China)

Cited by 116 publications

References 38 publications

Nutrient limitation and enzymolysis of phosphorus in Meiliang Bay, Lake Taihu, during algal blooms

Nutrient limitation and enzymolysis of phosphorus in Meiliang Bay, Lake Taihu, during algal blooms

Uncovering state‐dependent relationships in shallow lakes using Bayesian latent variable regression

Seeking alternative stable states in a deep lake

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