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Functional diversity of phytoplankton highlights long‐term gradual regime shift in the middle section of the Danube River due to global warming,human impacts and oligotrophication 
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下载免费PDF全文 András Abonyi Éva Ács András Hidas István Grigorszky Gábor Várbíró Gábor Borics Keve Tihamér Kiss 《Freshwater Biology》2018,63(5):456-472
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《Ecology letters》2017,20(1):98-111
Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer ‘growing seasons’. We executed the first global quantitative synthesis on under‐ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter‐summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake‐specific, species‐specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass. 相似文献
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Hao Wang Hui Fu Zihao Wen Changbo Yuan Xiaolin Zhang Leyi Ni Te Cao 《Ecology and evolution》2021,11(14):9827
Spatiotemporal variation in community composition is of considerable interest in ecology. However, few studies have focused on seasonal variation patterns in taxonomic and functional community composition at the fine scale. As such, we conducted seasonal high‐density sampling of the submerged macrophyte community in Hongshan Bay of Erhai Lake in China and used the generalized dissimilarity model (GDM) to evaluate the effects of environmental factors and geographic distance on taxonomic and functional beta diversity as well as corresponding turnover and nestedness components. At the fine scale, taxonomic turnover and nestedness as well as functional turnover and nestedness showed comparable contributions to corresponding taxonomic and functional beta diversity, with different importance across seasons. All taxonomic and functional dissimilarity metrics showed seasonal variation. Of note, taxonomic beta diversity was highest in summer and lowest in winter, while functional beta diversity showed the opposite pattern. Taxonomic and functional turnover showed similar change patterns as taxonomic and functional beta diversity. Taxonomic nestedness was low in summer and high in winter. Functional nestedness was also lower in summer. These results suggest that under extreme environmental conditions, both turnover and nestedness can exist at the fine scale and seasonal community composition patterns in submerged macrophytes should be considered. Future investigations on community assembly mechanisms should pay greater attention to long‐term dynamic characteristics and functional information. 相似文献
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Volker H. W. Rudolf 《Freshwater Biology》2020,65(4):745-756
- Shifts in the fundamental and realised niche of individuals during their ontogeny are ubiquitous in nature, but we know little about what aspects of the niche change and how these changes vary across species within communities. However, this knowledge is essential to predict the dynamics of populations and communities and how they respond to environmental change.
- Here I introduce a range of metrics to describe different aspects of shifts in the realised trophic niche of individuals based on stable isotopes. Applying this multi-variate approach to 2,272 individuals from 13 taxonomic and functional distinct species (Amphibia, Hemiptera, Coleoptera, Odonata) sampled in natural pond communities allowed me to: (1) describe and quantify the diversity of trophic niche shift patterns over ontogeny in multi-dimensional space, and (2) identify what aspects of ontogenetic shifts vary across taxa, and functional groups.
- Results revealed that species can differ substantially in which aspects of the trophic niche change and how they change over ontogeny. Interestingly, patterns of ontogenetic niche shifts grouped in distinct taxonomic clusters in multi-variate space, including two distinct groups of predators (Hemiptera versus Odonata). Given the differences in traits (especially feeding mode) across groups, this suggests that differences in ontogenetic niche shifts across species could at least partially be explained by variation in traits and functional roles of species.
- These results emphasise the importance of a multivariate approach to capture the large diversity of trophic niche shifts patterns possible in natural communities and suggest that differences in ontogenetic niche shifts follow general patterns.
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Top predator foraging strategy and prey base community composition can influence food web structure and function. To investigate the role of functional trait diversity and taxonomic richness in determining food chain length and energy flow in high elevation desert streams, we examined aquatic invertebrate community data along with carbon and nitrogen stable isotope analysis of a top predator, Abedus herberti (giant water bug). We also examined isotopic niche differences across different levels of population structure and seasons. We hypothesized that communities with higher richness would have longer food chains. We found food chain length did not vary substantially across a wide taxonomic and functional richness gradient, which contradicts theoretical mechanisms stating that more resources or higher functional diversity should lead to longer food chains. The isotopic niche of A. herberti was conserved across seasons and sites, and the majority of carbon in tissues came from allochthonous materials. Stable isotopes suggested that A. herberti occupy similar feeding niches in spring and autumn, despite seasonal changes in stream conditions, leaf litter inputs, and invertebrate community structure. Due to the strong aquatic–terrestrial linkages we identified, human activities and climate-driven alterations to the adjacent terrestrial environment may affect the dynamics and integrity of the within-stream ecosystem.
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Sandra Gran‐Stadniczeko Elianne Egge Vladyslava Hostyeva Ramiro Logares Wenche Eikrem Bente Edvardsen 《The Journal of eukaryotic microbiology》2019,66(3):494-513
Protist community composition and seasonal dynamics are of major importance for the production of higher trophic levels, such as zooplankton and fish. Our aim was to reveal how the protist community in the Skagerrak changes through the seasons by combining high‐throughput sequencing and microscopy of plankton collected monthly over two years. The V4 region of the 18S rRNA gene was amplified by eukaryote universal primers from the total RNA/cDNA. We found a strong seasonal variation in protist composition and proportional abundances, and a difference between two depths within the euphotic zone. Highest protist richness was found in late summer‐early autumn, and lowest in winter. Temperature was the abiotic factor explaining most of the variation in diversity. Dinoflagellates was the most abundant and diverse group followed by ciliates and diatoms. We found about 70 new taxa recorded for the first time in the Skagerrak. The seasonal pattern in relative read abundance of major phytoplankton groups was well in accordance with microscopical biovolumes. This is the first metabarcoding study of the protist plankton community of all taxonomic groups and through seasons in the Skagerrak, which may serve as a baseline for future surveys to reveal effects of climate and environmental changes. 相似文献
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Trait-based approaches have become increasingly important and valuable in understanding phytoplankton community assembly and composition. These approaches allow for comparisons between water bodies with different species composition. We hypothesize that similar changes in environmental conditions lead to similar responses with regard to functional traits of phytoplankton communities, regardless of trophic state or species composition. We studied the phytoplankton (species composition, community trait mean and diversity) of five reservoirs in Brazil along a trophic gradient from ultra-oligotrophic to meso-eutrophic. Samples at two seasons (summer/rainy and winter/dry) with a horizontal and vertical resolution were taken. Using multivariate analysis, the five reservoirs separated, despite some overlap, according to their environmental variables (mainly total phosphorus, conductivity, pH, chlorophyll a). However, between the seasonal periods, the reservoirs shifted in a similar direction in the multi-dimensional space. The seasonal response of the overall phytoplankton community trait mean differed between the ultra-oligotrophic and the other reservoirs, with three reservoirs exhibiting a very similar community trait mean despite considerable differences in species composition. Within-season differences between different water layers were low. The functional diversity was also unrelated to the trophic state of the reservoirs. Thus, seasonal environmental changes had strong influence on the functional characteristics of the phytoplankton community in reservoirs with distinct trophic condition and species composition. These results demonstrate that an ataxonomic trait-based approach is a relevant tool for comparative studies in phytoplankton ecology. 相似文献
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Huimin Xu Dayong Zhao Jin Zeng Congcong Jiao Zhongbo Yu Qinglong L. Wu 《Freshwater Biology》2020,65(8):1363-1375
- Understanding the successional patterns of microbial communities during a phytoplankton bloom is crucial for predicting the compositional and functional stability of lake ecosystems in response to the disturbance of a bloom. Previous studies on bacterial communities associated with blooms have rarely studied the dynamics of these communities. The successional patterns of bacterial communities within different micro-habitats (i.e. water column versus particles) and mechanisms that shape these communities that differ in composition and structure remain unclear.
- We selected a eutrophic urban lake to investigate the succession of bacterial communities during a bloom. We divided the bacterial communities into free-living (FL) and particle-attached (PA) groups based on their different lifestyles. The amplicon-based 16S rRNA gene high-throughput sequencing technology was used to obtain bacterial community composition and phylogenetic structure.
- Our study showed distinct successional patterns between FL and PA bacterial communities, and the two bacterial lifestyles showed different responses and resilience to the bloom, in terms of diversity and relative abundance of bacterial taxa. Alpha-diversity of the PA bacterial community decreased during the bloom, whereas that of the FL bacterial community increased. More taxa in the FL bacterial community showed resilience after the disturbance than in the PA bacterial community.
- The influence of phytoplankton blooms on the assembly of the bacterial community can be viewed as niche selection that led to the decrease in the relative importance of stochastic processes in shaping both FL and PA bacterial communities. This study shows the ecological significance of the bacterial community response to bloom events in lakes. It also shows that assembly processes differ for bacterial communities that have different lifestyles in lake ecosystems disturbed by phytoplankton blooms.