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- Angeler, David, et al.
(författare)
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Assessing and managing freshwater ecosystems vulnerable to environmental change
- 2014
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Ingår i: AMBIO: A Journal of the Human Environment. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 43, s. 113-129
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Tidskriftsartikel (refereegranskat)abstract
- Freshwater ecosystems are important for global biodiversity and provide essential ecosystem services. There is consensus in the scientific literature that freshwater ecosystems are vulnerable to the impacts of environmental change, which may trigger irreversible regime shifts upon which biodiversity and ecosystem services may be lost. There are profound uncertainties regarding the management and assessment of the vulnerability of freshwater ecosystems to environmental change. Quantitative approaches are needed to reduce this uncertainty. We describe available statistical and modeling approaches along with case studies that demonstrate how resilience theory can be applied to aid decision-making in natural resources management. We highlight especially how long-term monitoring efforts combined with ecological theory can provide a novel nexus between ecological impact assessment and management, and the quantification of systemic vulnerability and thus the resilience of ecosystems to environmental change.
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- Angeler, David, et al.
(författare)
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Effects of nutrient and water level changes on the composition and size structure of zooplankton communities in shallow lakes under different climatic conditions: a pan-European mesocosm experiment
- 2017
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Ingår i: Aquatic Ecology. - : Springer Science and Business Media LLC. - 1386-2588 .- 1573-5125. ; 51, s. 257-273
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Tidskriftsartikel (refereegranskat)abstract
- Lentic ecosystems act as sentinels of climate change, and evidence exists that their sensitivity to warming varies along a latitudinal gradient. We assessed the effects of nutrient and water level variability on zooplankton community composition, taxonomic diversity and size structure in different climate zones by running a standardised controlled 6-months (May to November) experiment in six countries along a European north-south latitudinal temperature gradient. The mesocosms were established with two different depths and nutrient levels. We took monthly zooplankton samples during the study period and pooled a subsample from each sampling to obtain one composite sample per mesocosm. We found a significant effect of temperature on the community composition and size structure of the zooplankton, whereas no effects of water depth or nutrient availability could be traced. The normalised size spectrum became flatter with increasing temperature reflecting higher zooplankton size diversity due to higher abundance of calanoid copepods, but did not differ among depths or nutrient levels. Large-bodied cladocerans such as Daphnia decreased with temperature. Taxonomic diversity was positively related to size diversity, but neither of the two diversity measures demonstrated a clear pattern along the temperature gradient nor with nutrient and water levels. However, genus richness decreased at the warm side of the temperature gradient. Our experiment generally supports recent empirically based findings that a continuing temperature increase may result in lower genus richness and lower abundance of large-sized zooplankton grazers, the latter likely resulting in reduced control of phytoplankton.
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- Angeler, David, et al.
(författare)
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Effects of trophic status, water level, and temperature on shallow lake metabolism and metabolic balance: A standardized pan-European mesocosm experiment
- 2019
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 64, s. 616-631
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Tidskriftsartikel (refereegranskat)abstract
- Important drivers of gross primary production (GPP) and ecosystem respiration (ER) in lakes are temperature, nutrients, and light availability, which are predicted to be affected by climate change. Little is known about how these three factors jointly influence shallow lakes metabolism and metabolic status as net heterotrophic or autotrophic. We conducted a pan-European standardized mesocosm experiment covering a temperature gradient from Sweden to Greece to test the differential temperature sensitivity of GPP and ER at two nutrient levels (mesotrophic or eutrophic) crossed with two water levels (1 m and 2 m) to simulate different light regimes. The findings from our experiment were compared with predictions made according the metabolic theory of ecology (MTE). GPP and ER were significantly higher in eutrophic mesocosms than in mesotrophic ones, and in shallow mesocosms compared to deep ones, while nutrient status and depth did not interact. The estimated temperature gains for ER of similar to 0.62 eV were comparable with those predicted by MTE. Temperature sensitivity for GPP was slightly higher than expected similar to 0.54 eV, but when corrected for daylight length, it was more consistent with predictions from MTE similar to 0.31 eV. The threshold temperature for the switch from autotrophy to heterotrophy was lower under mesotrophic (similar to 11 degrees C) than eutrophic conditions (similar to 20 degrees C). Therefore, despite a lack of significant temperature-treatment interactions in driving metabolism, the mesocosm's nutrient level proved to be crucial for how much warming a system can tolerate before it switches from net autotrophy to net heterotrophy.
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- Angeler, David, et al.
(författare)
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Identifying resilience mechanisms to recurrent ecosystem perturbations
- 2010
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 164, s. 231-241
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Tidskriftsartikel (refereegranskat)abstract
- The complex nature of ecological systems limits the unambiguous determination of mechanisms that drive resilience to natural disturbance or anthropogenic stress. Using eight-year time series data from boreal lakes with and without bloom formation of an invasive alga (Gonyostomum semen, Raphidophyceae), we studied resilience of phytoplankton communities in relation to recurring bloom impacts. We first characterized phytoplankton community dynamics in both lake types using univariate metrics of community structure (evenness, species richness, biovolume and Simpson diversity). All metrics, except species richness, were substantially altered and showed an inherent stronger variability in bloom lakes relative to reference lakes. We assessed resilience mechanisms using a multivariate time series modelling technique. The models captured clear successional dynamics of the phytoplankton communities in all lakes, whereby different groups of species were substituted sequentially over the ice-free period. The models also identified that G. semen impacts in bloom lakes were only manifested within a single species group, not across species groups, highlighting the rapid renewal of the phytoplankton communities upon bloom collapse. These results provide empirical support of the cross-scale resilience model. Cross-scale resilience could provide an explanation for the paradox that similar species richnesses are seen in bloom-forming lakes and reference lakes despite the clear difference between the community features of the two different sets of lakes investigated.
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- Angeler, David, et al.
(författare)
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Managing ecosystems without prior knowledge: pathological outcomes of lake liming
- 2017
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Ingår i: Ecology and Society. - 1708-3087. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Management actions often need to be taken in the absence of ecological information to mitigate the impact of pressing environmental problems. Managers counteracted the detrimental effects of cultural acidification on aquatic ecosystems during the industrial era using liming to salvage biodiversity and ecosystem services. However, historical contingencies, i.e., whether lakes were naturally acidic or degraded because of acidification, were largely unknown and therefore not accounted for in management. It is uncertain whether liming outcomes had a potentially detrimental effect on naturally acidic lakes. Evidence from paleolimnological reconstructions allowed us to analyze community structure in limed acidified and naturally acidic lakes, and acidified and circumneutral references. We analyzed community structure of phytoplankton, zooplankton, macroinvertebrates (littoral, sublittoral, profundal), and fish between 2000 and 2004. Naturally acidic limed lakes formed communities that were not representative of the other lake types. The occurrence of fish species relevant for ecosystem service provisioning (fisheries potential) in naturally acidic limed lakes were confounded by biogeographical factors. In addition, sustained changes in water quality were conducive to harmful algal blooms. This highlights a pathological outcome of liming lakes when their naturally acidic conditions are not accounted for. Because liming is an important social-ecological system, sustained ecological change of lakes might incur undesired costs for societies in the long term.
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- Angeler, David, et al.
(författare)
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Revealing the organization of complex adaptive systems through multivarate time series modeling
- 2011
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Ingår i: Ecology and Society. - 1708-3087. ; 16, s. 5-
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Tidskriftsartikel (refereegranskat)abstract
- Revealing the adaptive responses of ecological, social, and economic systems to a transforming biosphere is crucial for understanding system resilience and preventing collapse. However, testing the theory that underpins complex adaptive system organization (e.g., panarchy theory) is challenging. We used multivariate time series modeling to identify scale-specific system organization and, by extension, apparent resilience mechanisms. We used a 20-year time series of invertebrates and phytoplankton from 26 Swedish lakes to test the proposition that a few key-structuring environmental variables at specific scales create discontinuities in community dynamics. Cross-scale structure was manifested in two independent species groups within both communities across lakes. The first species group showed patterns of directional temporal change, which was related to environmental variables that acted at broad spatiotemporal scales (reduced sulfate deposition, North Atlantic Oscillation). The second species group showed fluctuation patterns, which often could not be explained by environmental variables. However, when significant relationships were found, species–group trends were predicted by variables (total organic carbon, nutrients) that acted at narrower spatial scales (i.e., catchment and lake). Although the sets of environmental variables that predicted the species groups differed between phytoplankton and invertebrates, the scale-specific imprints of keystone environmental variables for creating cross-scale structure were clear for both communities. Temporal trends of functional groups did not track the observed structural changes, suggesting functional stability despite structural change. Our approach allows for identifying scale-specific patterns and processes, thus providing opportunities for better characterization of complex adaptive systems organization and dynamics. This, in turn, holds potential for more accurate evaluation of resilience in disparate system types (ecological, social, economic)
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