Translating Regime Shifts in Shallow Lakes into Changes in Ecosystem Functions and Services

Hilt, Sabine; Jeppesen, Erik; Veraart, Annelies J.; Kosten, Sarian

doi:10.1093/biosci/bix106

Cited by 177 publications

(127 citation statements)

References 53 publications

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“…Shallow lakes can undergo transitions between macrophytedominated clear and phytoplankton-dominated turbid water states; a switch may occur when continued stress causes the system to surpass a breakpoint and propel it toward a new regime maintained by a different set of feedbacks (Moss et al, 2003;Scheffer et al, 2009;Scheffer, Carpenter, Foley, Folkes, & Walker, 2001;Scheffer, Hosper, Meiger, Moss, & Jeppesen, 1993). Nutrient loading is one source of such stress, leading to a switch from clear water to turbid conditions; the latter state is ecologically and economically detrimental, owing to the loss of freshwater biodiversity and reduction in water quality (Hilt, Brothers, Jeppesen, Veraart, & Kosten, 2017). Although the loss of macrophytes is a well-known consequence of eutrophication, the ecological mechanisms that precede macrophyte loss are not well known (see review by Phillips, Wilby, & Moss, 2016).…”

Section: Introductionmentioning

confidence: 99%

Macrophytes moderate the taxonomic and functional composition of phytoplankton assemblages during a nutrient loading experiment

et al. 2019

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Ponds and shallow lakes are sensitive to eutrophication, which often increases turbidity and produces toxic algal blooms. Previous research has found that the presence of macrophytes in shallow water bodies can mitigate the effects of nutrient loading by promoting water clarity and inhibiting phytoplankton growth. However, there is still little known about how macrophyte abundance modifies the response of phytoplankton taxonomic assemblages, particularly their functional composition, to nutrient loading. We investigated how macrophyte abundance altered phytoplankton assemblages using experimental ponds that were treated with a nutrient press. Natural communities of phytoplankton, zooplankton, and fish were seeded in ponds with one of three levels of macrophyte abundance that received weekly nutrient additions. A total of nine ponds (each treatment in triplicate) were monitored for 76 days. Analyses of Shannon's diversity and functional dispersion revealed significant variation in phytoplankton assemblage composition among macrophyte treatments and through time. Phytoplankton biovolume, community metrics, and the dominant traits were generally more stable in the high macrophyte treatment ponds. Although nutrient loading did not induce a regime change to a turbid, phytoplankton‐dominated state, phytoplankton assemblages did shift to a dominance of larger, inedible taxa and metaphyton became more abundant in ponds with macrophytes and zooplankton assemblages shifted to smaller species. Our study demonstrates how functional traits and functional diversity metrics can provide richer insights into the dynamics and causes of shifts in shallow freshwater ecosystems. Macrophyte densities clearly played a significant role in shaping phytoplankton assemblages. Based on the functional traits of phytoplankton distinguished among treatments, we inferred that competition for light, grazing, and, probably, allelochemicals were mechanisms through which macrophytes mediated changes in phytoplankton assemblages.

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Section: Introductionmentioning

confidence: 99%

Macrophytes moderate the taxonomic and functional composition of phytoplankton assemblages during a nutrient loading experiment

et al. 2019

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“…Turbid states are associated with reduced ecosystem functions and services compared to clear water ponds and shallow lakes, the extent of which is not yet fully understood (Hilt et al. ).…”

Section: Introductionmentioning

confidence: 99%

“…Once established, the turbid state tends to be maintained despite external nutrient load reductions because of new positive feedbacks including the resuspension of nutrient-rich sediments in the absence of macrophytes (Scheffer et al 1993). Turbid states are associated with reduced ecosystem functions and services compared to clear water ponds and shallow lakes, the extent of which is not yet fully understood (Hilt et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Shifts in algal dominance in freshwater experimental ponds across differing levels of macrophytes and nutrients

et al. 2018

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Abstract. Excess nutrient loading into ponds and shallow lakes can lead to undesirable algal growth and a shift to a turbid state. Previous work has suggested that such an ecosystem transition may be mediated by the biotic constituents of the habitat and food web; however, earlier experiments have been conducted at coarse temporal resolution and have typically used a single initial density of macrophytes, a key structural component of ponds and shallow lakes. To address these gaps, we tested the hypotheses that experimental ponds with lower macrophyte densities and more rapid increases in nutrient loading would shift to phytoplankton dominance, whereas higher macrophyte densities and slower, lower concentration nutrient inputs would maintain a clear state. Ponds containing plankton and juvenile fish were assigned to treatments with none, low, or high macrophyte densities, and weekly, high or biweekly (i.e., fortnightly), low nutrient inputs. Using additive mixed-effects models, we demonstrated that temporal trajectories of phytoplankton biomass were explained by macrophyte density in interaction with biomass of important zooplankton grazers (Bosminidae, Sididae, and Daphniidae), as well as with pH and time. Phytoplankton biomass followed a convex unimodal trajectory in ponds with no or low macrophytes (muted in the latter), and minimal increases in high macrophyte treatments. Declines in phytoplankton attributable to top-down control likely freed resources for periphyton and metaphyton, which subsequently became abundant in ponds without and with macrophytes, respectively. Our results demonstrate that high densities of macrophytes, combined with herbivory and competition for light between phytoplankton and metaphyton, enhance resilience of the clear water state to the undesirable effects associated with eutrophication.

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“…Small ponds also contribute substantially to the global carbon budget, despite their small size (Holgerson & Raymond, 2016). In small ponds, submerged macrophytes are an important structural component (Jeppesen, Sondergaard, Sondergaard, & Christofferson, 1998) and systems dominated by these aquatic plants have great potential for high carbon burial (Hilt, Brothers, Jeppesen, Veraart, & Kosten, 2017;Jeppesen et al, 2016). However, the efficiency of carbon burial can vary depending on environmental conditions such as oxygen availability (Sobek et al, 2009), latitude (Alin & Johnson, 2007), nutrient availability (Heathcote & Downing, 2012), and possibly temperature (e.g., Mendonça et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte‐dominated systems with zero net effect on carbon burial

Velthuis

Kosten

Aben

et al. 2018

Global Change Biology

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Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year-round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year-round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m yaer (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m year in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte-dominated systems, while not necessarily affecting net carbon burial on a system scale.

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Translating Regime Shifts in Shallow Lakes into Changes in Ecosystem Functions and Services

Cited by 177 publications

References 53 publications

Macrophytes moderate the taxonomic and functional composition of phytoplankton assemblages during a nutrient loading experiment

Macrophytes moderate the taxonomic and functional composition of phytoplankton assemblages during a nutrient loading experiment

Shifts in algal dominance in freshwater experimental ponds across differing levels of macrophytes and nutrients

Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte‐dominated systems with zero net effect on carbon burial

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