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- Kovacs, Csilla, et al.
(författare)
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Benthic diatom communities along pH and TP gradients in Hungarian and Swedish streams
- 2006
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 18:2, s. 105-117
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Tidskriftsartikel (refereegranskat)abstract
- Benthic diatoms are widely used in Europe to assess ecological status of running waters. The aim of this study was to develop models to predict average pH and total phosphorus (TP) for European stream monitoring using combined diatom data-sets from Hungary and Sweden. As first step, the relationship between the measured environmental variables and the distribution of the taxa was checked by classification by using cluster-analysis and CCA. Diatom data separated clearly along the main hydrogeochemical parameters (e.g. alkalinity, pH). Concerning nutrients, TP was the most determinant factor. Predictive value of the TP model (r = 0.96) is high only for the Hungarian data and the pH model (r = 0.97) can be used in both phycogeographical regions.
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| 4. |
- Szabo, Beata, et al.
(författare)
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Structuring forces and -diversity of benthic diatom metacommunities in soda pans of the Carpathian Basin
- 2018
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Ingår i: European journal of phycology. - : Informa UK Limited. - 0967-0262 .- 1469-4433. ; 53:2, s. 219-229
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Tidskriftsartikel (refereegranskat)abstract
- Small soda lakes represent one of the most vulnerable ecosystem types due to their high hydrological sensitivity to climate change and anthropogenic interventions. Since diatoms are excellent bioindicators, determining the -diversity and the structuring dynamics of diatom metacommunities can provide valuable information for conservation planning for soda pans. In this study, two diatom metacommunities were surveyed monthly during a one-year period from distinct regions of the Carpathian basin: the Fert-Hansag National Park (FH) between 2013 and 2014, and the Danube-Tisza Interfluve (DT) between 2014 and 2015. We explored whether -diversity of diatom assemblages in the two regions is enhanced by species turnover or nestedness (related to richness differences) and investigated the role of deterministic and stochastic processes in shaping -diversity patterns. Furthermore, we evaluated the contribution of environmental variables, geographic distance and temporal variation to community structure. High -diversity (>90%) was revealed for both metacommunities, and was maintained primarily by species turnover. Within the metacommunity of the DT where the natural hydrological cycle of soda pans is not disturbed, diatom communities assembled mainly due to the selection force of environment at a spatiotemporal scale. In the soda pans located in the habitat reconstruction area of the FH, besides species-sorting, significant temporal variation in community structure appeared as a result of water management and periodic water supply. Our results point to the need for a conservation management strategy which maintains the natural hydrological regime of small saline lakes, and therefore their habitat heterogeneity which is of high conservation value.
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| 7. |
- Yang, Yang, et al.
(författare)
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Effects of winter severity on spring phytoplankton development in a temperate lake (Lake Erken, Sweden)
- 2016
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 780:1, s. 47-57
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Tidskriftsartikel (refereegranskat)abstract
- Phytoplankton seasonal succession has been linked to a variety of serial environmental changes, especially weather- and climate-induced physical forcing. This study compared spring phytoplankton dynamics after winters of different severity (cold, normal, and warm) in Lake Erken, Sweden. The spring diatom bloom was dominated by different functional groups: group A (centric diatoms 5-10 mu m) after cold winters, B (centric diatoms > 15 mu m) after normal winters, and P (Aulacoseira granulata, Fragilaria crotonensis) after warm winters. Our results suggest that weather-related processes were the primary external drivers accounting for differences in spring phytoplankton dynamics in Lake Erken. Spring phytoplankton are influenced by overwintering species from the last autumn that can initiate the following spring bloom. Average taxonomic distinctness of the spring community was assessed using a new biodiversity measurement that incorporates taxonomic relatedness information. This value was lower than expected after warm and cold winters, which had winter air temperature 1A degrees C deviation from an average value calculated over 21 years. Such winters increased the level of disturbance or stress to the lake, resulting in a spring with less diverse phytoplankton by narrowing the niche for species with various ecological requirements.
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| 8. |
- Yang, Yang, 1985-, et al.
(författare)
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Repetitive baselines of phytoplankton succession in an unstably stratified temperate lake (Lake Erken, Sweden) : a long-term analysis
- 2016
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 764:1, s. 211-227
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Tidskriftsartikel (refereegranskat)abstract
- The seasonal development of phytoplankton is a sequence of consecutive events with waxes and wanes of biomass and compositional shifts. This study analyzed 16 years data in Lake Erken, Sweden and revealed four baselines of phytoplankton succession with their underlying drivers. Results showed that there were two diatom-dominated phases annually. The vernal community was dominated by centric diatoms larger than 15 A mu m (functional groups B and C) which were fast-growing diatoms being highly efficient in the use of nutrients. The autumn community was comprised mainly meroplanktonic mixing-dependent Aulacoseira granulata and Fragilaria sp. (MP and P) or/and large centric diatoms (B). Between the two mixing-phases with diatoms, a Gloeotrichia echinulata (H 2) bloom occurred due to its preference for a stratified water column with elevated water temperatures and high light availability. The summer stratification in Lake Erken was weak and short, thus, favoring meroplanktonic diatoms to peak once the lake turned over in early autumn. Lake Erken represents an intermediate case between a highly mixed polymictic lake and a lake with strong summer stratification, where the observed stratification patterns allowed the development of an autumn diatom phase similar, by extent, to the vernal one and mainly dominated by meroplanktonic diatoms.
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