| 1. |
- Haase, Peter, et al.
(författare)
-
Moderate warming over the past 25 years has already reorganized stream invertebrate communities
- 2019
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 658, s. 1531-1538
-
Tidskriftsartikel (refereegranskat)abstract
- Climate warming often results in species range shifts, biodiversity loss and accumulated climatic debts of biota (i.e. slower changes in biota than in temperature). Here, we analyzed the changes in community composition and temperature signature of stream invertebrate communities over 25 years (1990-€“2014), based on a large set of samples (n = 3782) over large elevation, latitudinal and longitudinal gradients in central Europe. Although warming was moderate (average 0.5°C), we found a strong reorganization of stream invertebrate communities. Total abundance (+35.9%) and richness (+39.2%) significantly increased. The share of abundance (TA) and taxonomic richness (TR) of warm-dwelling taxa (TA: +73.2%; TR: +60.2%) and medium-temperature-dwelling taxa (TA: +0.4%; TR: +5.8%) increased too, while cold-dwelling taxa declined (TA: -61.5%; TR: -ˆ’47.3%). The community temperature index, representing the temperature signature of stream invertebrate communities, increased at a similar pace to physical temperature, indicating a thermophilization of the communities and, for the first time, no climatic debt. The strongest changes occurred along the altitudinal gradient, suggesting that stream invertebrates use the spatial configuration of river networks to track their temperature niche uphill. Yet, this may soon come to an end due to the summit trap effect. Our results indicate an ongoing process of replacement of cold-adapted species by thermophilic species at only 0.5 °C warming, which is particularly alarming in the light of the more drastic climate warming projected for coming decades.
|
|
| 2. |
- Jourdan, Jonas, et al.
(författare)
-
Effects of changing climate on European stream invertebrate communities : A long-term data analysis
- 2018
-
Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 621, s. 588-599
-
Tidskriftsartikel (refereegranskat)abstract
- Long-term observations on riverine benthic invertebrate communities enable assessments of the potential impacts of global change on stream ecosystems. Besides increasing average temperatures, many studies predict greater temperature extremes and intense precipitation events as a consequence of climate change. In this study we examined long-term observation data (10–32years) of 26 streams and rivers from four ecoregions in the European Long-Term Ecological Research (LTER) network, to investigate invertebrate community responses to changing climatic conditions. We used functional trait and multi-taxonomic analyses and combined examinations of general long-term changes in communities with detailed analyses of the impact of different climatic drivers (i.e., various temperature and precipitation variables) by focusing on the response of communities to climatic conditions of the previous year. Taxa and ecoregions differed substantially in their response to climate change conditions. We did not observe any trend of changes in total taxonomic richness or overall abundance over time or with increasing temperatures, which reflects a compensatory turnover in the composition of communities; sensitive Plecoptera decreased in response to warmer years and Ephemeroptera increased in northern regions. Invasive species increased with an increasing number of extreme days which also caused an apparent upstream community movement. The observed changes in functional feeding group diversity indicate that climate change may be associated with changes in trophic interactions within aquatic food webs. These findings highlight the vulnerability of riverine ecosystems to climate change and emphasize the need to further explore the interactive effects of climate change variables with other local stressors to develop appropriate conservation measures.
|
|
| 3. |
- Pilotto, Francesca, et al.
(författare)
-
Decline in niche specialization and trait β-diversity in benthic invertebrate communities of Central European low-mountain streams over 25 years
- 2022
-
Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 810
-
Tidskriftsartikel (refereegranskat)abstract
- Biotic homogenization is one of the key aspects of the current biodiversity crisis. Here we analyzed the trends of three facets of niche homogenization, i.e. niche specialization, trait α-diversity and spatial β-diversity, over a period of 25 years (1990–2014) using a large dataset of 3782 stream benthic invertebrate samples collected from central European low-mountain streams. We studied a set of traits describing the ecological niche of species and their functions: body size, feeding groups, substrate preferences, flow preferences, stream zonation preferences and saprobity. Trait composition changed significantly during the study period, and we identified an overall increase in niche homogenization. Specifically, community niche specialization significantly decreased by 20.3% over the 25-year period, with declines ranging from −16.0 to −40.9% for zonation-, flow-, substrate-preferences, body size and feeding traits. Trait diversity did not change significantly, although we recorded significant decreases by −14.2% and −10.2% for flow- and substrate-preference and increases by 5.8% and 22.6% for feeding traits and zonation preference over the study period. Trait spatial β-diversity significantly decreased by −53.0%, with substrate-preference, feeding groups and flow-preference traits declining from −61.9% to −75.3% over the study period. This increased niche homogenization is likely driven by the increase of down-stream typical taxa, which are favored by warming temperatures. Further, it is in apparent contradiction with the recorded increase in abundance (+35.9%) and taxonomic richness (+39.2%) over the same period. Even such increases do not safeguard communities from undergoing niche homogenization, indicating that recovery processes may differ with regard to community taxonomic composition and traits. Our results emphasize the complexity of community responses to global change and warrant caution when founding conclusions based solely on single community metrics.
|
|
| 4. |
- Pilotto, Francesca, et al.
(författare)
-
Diverging response patterns of terrestrial and aquatic species to hydromorphological restoration
- 2019
-
Ingår i: Conservation Biology. - : John Wiley & Sons. - 0888-8892 .- 1523-1739. ; 33:1, s. 132-141
-
Tidskriftsartikel (refereegranskat)abstract
- Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodplain vegetation) biotic groups to 43 hydromorphological river restoration projects in Germany. All taxonomic groups responded positively to restoration, as shown by increased taxonomic richness (10–164%) and trait diversity (habitat, dispersal and mobility, size, form, life history, and feeding groups) (15–120%). Responses, however, were stronger for terrestrial than aquatic biota, and, contrary to our expectation, taxonomic responses were stronger than those of traits. Nevertheless, trait analysis provided mechanistic insights into the drivers of community change following restoration. Trait analysis for terrestrial biota indicated restoration success was likely enhanced by lateral connectivity and reestablishment of dynamic processes in the floodplain. The weaker response of aquatic biota suggests recovery was hindered by the persistence of stressors in the aquatic environment, such as degraded water quality, dispersal constraints, and insufficient hydromorphological change. Therefore, river restoration requires combined local- and regional-scale approaches to maximize the response of both aquatic and terrestrial organisms. Due to the contrasting responses of aquatic and terrestrial biota, the planning and assessment of river restoration outcomes should consider effects on both components of riverine landscapes.
|
|
