Browsing by Subject "vesiekologia"

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  • Laske, Sarah M.; Amundsen, Per‐Arne; Christoffersen, Kirsten S.; Erkinaro, Jaakko; Guðbergsson, Guðni; Hayden, Brian; Heino, Jani; Holmgren, Kerstin; Kahilainen, Kimmo K.; Lento, Jennifer; Orell, Panu; Östergren, Johan; Power, Michael; Rafikov, Ruslan; Romakkaniemi, Atso; Svenning, Martin‐A.; Swanson, Heidi; Whitman, Matthew; Zimmerman, Christian E. (Blackwell Scientific, 2022)
    Freshwater biology
    1. Climate change, biological invasions, and anthropogenic disturbance pose a threat to the biodiversity and function of Arctic freshwater ecosystems. Understanding potential changes in fish species distribution and richness is necessary, given the great importance of fish to the function of freshwater ecosystems and as a resource to humans. However, information gaps limit large-scale studies and our ability to determine patterns and trends in space and time. This study takes the first step in determining circumpolar patterns of fish species richness and composition, which provides a baseline to improve both monitoring and conservation of Arctic freshwater biodiversity. 2. Information on species presence/absence was gathered from the Circumpolar Biodiversity Monitoring Program's Freshwater Database and used to examine patterns of freshwater fish γ-, α-, and β-diversity across 234° of longitude in the Arctic. The metrics of diversity provided information on species richness and composition across hydrobasins, ecoregions, and Arctic zones. 3. Circumpolar patterns of fish species biodiversity varied with latitude, isolation, and coarse ecoregion characteristics; patterns were consistent with historic and contemporary barriers to colonisation and environmental characteristics. Gamma-diversity was lower in the high Arctic compared to lower latitude zones, but α-diversity did not decrease with increasing latitude below 71°N, reflecting glacial history. Alpha-diversity was reduced to a single species, Arctic charr Salvelinus alpinus, in ecoregions above 71°N, where γ-diversity was the lowest. Beta-diversity indicated little variation in the composition and richness of species across the High Arctic; at lower latitudes, ecoregions contained more species, although species composition turned over across large spatial extents. 4. In an analysis of five ecoregions in the circumpolar Arctic, physical isolation, and ecoregion area and topography were identified as strong drivers of γ-, α-, and β-diversity. Physical isolation reduced the γ- and α-diversity, and changes in β-diversity between adjacent locations were due mainly to losses in species richness, rather than due to differences in species composition. Heterogeneity of habitats, environmental gradients, and geographic distance probably contributed to patterns of fish dissimilarity within and across ecoregions. 5. This study presents the first analysis of large-scale patterns of freshwater fish biodiversity in the circumpolar Arctic. However, information gaps in space, time, and among taxonomic groups remain. Future inclusion of extensive archive and new data will allow future studies to test for changes and drivers of the observed patterns of biodiversity. This is important given the potential impacts of ongoing and accelerating climate change, land use, and biotic exchange on Arctic fish biodiversity.
  • Häggman, Alf (University of Helsinki, 1959)
  • Jyväsjärvi, Jussi; Lehosmaa, Kaisa; Aroviita, Jukka; Turunen, Jarno; Rajakallio, Maria; Marttila, Hannu; Tolkkinen, Mikko; Mykrä, Heikki; Muotka, Timo (Elsevier, 2021)
    Ecological Indicators 121 (2021), 106986
    Degradation of freshwater ecosystems requires efficient tools for assessing the ecological status of freshwater biota and identifying potential cause(s) for their biological degradation. While diatoms and macroinvertebrates are widely used in stream bioassessment, the potential utility of microbial communities has not been fully harnessed. Using data from 113 Finnish streams, we assessed the performance of aquatic leaf-associated fungal decomposers, relative to benthic macroinvertebrates and diatoms, in modelling-based bioassessment. We built multi-taxon niche -type predictive models for fungal assemblages by using genus-based and sequence-based identification levels. We then compared the models’ precision and accuracy in the prediction of reference conditions (number of native taxa) to corresponding models for macroinvertebrates and diatoms. Genus-based fungal model nearly equalled the accuracy and precision of our best model (macroinvertebrates), whereas the sequence-based model was less accurate and tended to overestimate the number of taxa. However, when the models were applied to streams disturbed by anthropogenic stressors (nutrient enrichment, sedimentation and acidification), alone or in combination, the sequence-based fungal assemblages were more sensitive than other taxonomic groups, especially when multiple stressors were present. Microbial leaf decomposition rates were elevated in sediment-stressed streams whereas decomposition attributable to leaf-shredding macroinvertebrates was accelerated by nutrients and decelerated by sedimentation. Comparison of leaf decomposition results to model output suggested that leaf decomposition rates do not detect effectively the presence of multiple simultaneous disturbances. The rapid development of global microbial database may soon enable species-level identification of leaf-associated fungi, facilitating a more precise and accurate modelling of reference conditions in streams using fungal communities. This development, combined with the sensitivity of aquatic fungi in detecting the presence of multiple human disturbances, makes leaf-associated fungal assemblages an indispensable addition in a stream ecologist’s toolbox.
  • Luotamo, Ilkka (University of Helsinki, 1971)
  • Koli, Lauri A. (University of Helsinki, 1953)
  • Salonen, Kalevi (University of Helsinki, 1972)
  • Panelius, O. Samuel (University of Helsinki, 1957)
  • Majala-Penttilä, Raili (University of Helsinki, 1982)
  • Hirvenoja, Mauri (University of Helsinki, 1954)
  • Laakso, Juho K. (University of Helsinki, 1953)
  • Tamminen, Timo (Vesihallitus. National Board of Waters, 1984)
    Vesientutkimuslaitoksen julkaisuja 56, 11-20
    Michaelis-Menten -kinetiikan lineaarimuunnokset luonnon mikrobiyhteisöjen tutkimuksessa
  • Kotilainen, Mauno J. (University of Helsinki, 1929)
  • Metsikkö, Eino (University of Helsinki, 1929)
  • Hanninen, Eeva (University of Helsinki, 1976)
  • Leinonen, Erkki (University of Helsinki, 1949)
  • Hämäläinen, Juha (University of Helsinki, 1988)
  • Tolvanen, Anja (University of Helsinki, 1975)
  • Ge, Yihao; Meng, Xingliang; Heino, Jani; García‐Girón, Jorge; Liu, Yang; Li, Zhengfei; Xie, Zhicai (Ecological Society of America, 2021)
    Ecosphere 12 (7), e03675
    Deterministic and stochastic processes are two major factors shaping community dynamics, but their relative importance remains unknown for many aquatic systems, including those in the high-elevation Qinghai–Tibet Plateau. Here, we explored the causes of multidimensional beta diversity patterns (i.e., taxonomic, functional, and phylogenetic) of a macroinvertebrate metacommunity in this large aquatic system by using multiple approaches (i.e., null models, phylogenetic signal testing, and ordination-based approaches). To obtain insights into community assembly mechanisms, we also analyzed beta diversity in two deconstructed sub-metacommunities (e.g., different tributaries and the main lake body). We found that most functional traits showed significant phylogenetic signals, indicating that the functional traits were profoundly influenced by evolutionary history. The null models showed randomness of functional and phylogenetic beta diversities for the whole basin and its tributaries, confirming the importance of stochasticity over deterministic processes in controlling community structure. However, both phylogenetic and functional community structures were clustered in the Qinghai Lake, probably reflecting the importance of environmental filtering. Ordination-based approaches also revealed that both environmental factors and spatial processes accounted for variation in taxonomic, functional, and phylogenetic beta diversity. More specifically, environmental filtering was more important than spatial processes for the functional dimension, but the opposite was true for the taxonomic and phylogenetic dimensions. The paleogeographic history of the Qinghai Lake basin may have contributed substantially to the prevalence of stochastic processes. Overall, this study provides a better understanding of ecological patterns and assembly mechanisms of macroinvertebrate communities across this poorly known high-elevation aquatic system that is highly sensitive to climate warming.