| 1. |
- Göthe, Emma, et al.
(författare)
-
Flow restoration and the impacts of multiple stressors on fish communities in regulated rivers
- 2019
-
Ingår i: Journal of Applied Ecology. - : John Wiley & Sons. - 0021-8901 .- 1365-2664. ; 56:7, s. 1687-1702
-
Tidskriftsartikel (refereegranskat)abstract
- River regulation for hydropower is undertaken worldwide, causing profound alterations to hydrological regimes and running water habitats. Regulated catchments are often subjected to additional stressors, arising inter alia from agriculture, forestry and industry, which are likely to interact with impacts of river regulation on fish and other biota. Such interactions are poorly understood, hindering planning of effective mitigation and restoration. We investigated fish responses to increased discharge (as a restoration measure) in regulated rivers in Sweden. We compiled electrofishing data from river channels downstream of hydropower dams, each of which either has or lacks a mandated minimum discharge corresponding to c. 5% of pre-regulation discharge. We further analysed interactions between flow restoration and co-occurring local and regional stressors. River channels without a mandated minimum discharge were characterized by a low diversity of fish species with traits favouring persistence under unpredictable environmental conditions, including omnivory, short life cycles and small size. Additional stressors further reduced diversity and increased dominance by broad-niched, opportunistic species. Both the presence and magnitude of a mandated minimum discharge were positively related to fish diversity and density, and the relative density of three economically and recreationally valuable species. However, the size of these relationships frequently varied with the presence of additional stressors. Increasing levels of hydrological degradation and reduced connectivity at the catchment scale reduced positive flow-ecology relationships and hindered the restoration of fish communities towards reference conditions. However, application of a mandated minimum discharge also assisted in mitigating impacts of some co-occurring stressors, especially reduced riparian integrity. Synthesis and applications. Additional stressors can strongly influence the outcomes of flow restoration for fish community diversity and composition. Our approach combining fish species and trait data from multiple flow restoration projects with information on additional stressors yielded valuable insights into factors affecting flow restoration success, useful for (a) identifying the systems most likely to benefit from mandated minimum flows, (b) modelling influences of multiple stressors on flow-ecology relationships, (c) prioritizing additional measures to manage co-occurring stressors and enhance outcomes from flow restoration.
|
|
| 2. |
- Truchy, Amélie, et al.
(författare)
-
Partitioning spatial, environmental, and community drivers of ecosystem functioning
- 2019
-
Ingår i: Landscape Ecology. - : Springer. - 0921-2973 .- 1572-9761. ; 34:10, s. 2371-2384
-
Tidskriftsartikel (refereegranskat)abstract
- Context: Community composition, environmental variation, and spatial structuring can influence ecosystem functioning, and ecosystem service delivery. While the role of space in regulating ecosystem functioning is well recognised in theory, it is rarely considered explicitly in empirical studies.Objectives: We evaluated the role of spatial structuring within and between regions in explaining the functioning of 36 reference and human-impacted streams.Methods: We gathered information on regional and local environmental variables, communities (taxonomy and traits), and used variance partitioning analysis to explain seven indicators of ecosystem functioning.Results: Variation in functional indicators was explained not only by environmental variables and community composition, but also by geographic position, with sometimes high joint variation among the explanatory factors. This suggests spatial structuring in ecosystem functioning beyond that attributable to species sorting along environmental gradients. Spatial structuring at the within-region scale potentially arose from movements of species and materials among habitat patches. Spatial structuring at the between-region scale was more pervasive, occurring both in analyses of individual ecosystem processes and of the full functional matrix, and is likely to partly reflect phenotypic variation in the traits of functionally important species. Characterising communities by their traits rather than taxonomy did not increase the total variation explained, but did allow for a better discrimination of the role of space.Conclusions: These results demonstrate the value of accounting for the role of spatial structuring to increase explanatory power in studies of ecosystem processes, and underpin more robust management of the ecosystem services supported by those processes.
|
|
