scholarly journals Geographic pattern of phytoplankton community and their drivers in lakes of middle and lower reaches of Yangtze River floodplain, ChinaGeographic pattern of phytoplankton community and their drivers in lakes of middle and lower reaches of Yangtze River floodplain, China

2021 ◽  
Author(s):  
Zhe Xiao ◽  
Hua Li ◽  
Xiaochuang Li ◽  
Renhui Li ◽  
Shouliang Huo ◽  
...  
Keyword(s):  
Stochastic Processes ◽  
Yangtze River ◽  
Phytoplankton Community ◽  
Species Turnover ◽  
Mantel Test ◽  
Cyanobacterial Blooms ◽  
Geographic Pattern ◽  
River Floodplain ◽  
Spatial Factors ◽  
Biogeographic Patterns

Abstract Disentangling the relative contributions of deterministic and stochastic processes were critical to compressive understanding of underlying mechanism governing geographic pattern and assembly of phytoplankton community, while it was seldom performed in connected lakes under human pressure. Here, we investigated phytoplankton community pattern in relation to environmental and spatial factors over 81 lakes located in middle and lower reaches of Yangtze River (MLYR) floodplain, where many lakes suffered eutrophication and cyanobacterial blooms. A majority of MLYR lakes had higher phytoplankton abundance surpassing 107 cells/L, and were dominated by common bloom-forming cyanobacterial genera, including Pseudanabaena, Microcystis, Merismopedia, Dolichospermum, Limnothrix, and Raphidiopsis. Phytoplankton community exhibited a striking geographical pattern both for taxonomic and functional compositions, while functional groups were less sensitive and disimmilarity in communities displayed no significant increases with increasing geographical distance. Further, species richness explained much higher percentage of community variations than species turnover, indicating a reduced effect of environmental filtering of phytoplankton species with tolerance to similar environments in connected MLYR lakes. Both deterministic and stochastic processes governed assembly and biogeographic of phytoplankton community. Variation partition analysis showed spatial factors exhibited greater influence on phytoplankton community compared to environmental variables. The stronger influence of spatial factors was further demonstrated by Mantel test and neutral community model. These findings indicate deterministic and stochastic processes exhibited similar biogeographic patterns for phytoplankton community in MLYR lakes, but stochastic process was overwhelmingly dominated. Moreover, a large proportion of unexplained variation implies complex interactions exist to shape assembly mechanism of phytoplankton community in MLYR lakes.

scholarly journals Priority sites and conservation gaps of wintering waterbirds in the Yangtze River floodplain

2020 ◽  
Vol 30 (10) ◽  
pp. 1617-1632
Author(s):  
Shaoxia Xia ◽  
Xiubo Yu ◽  
Jinyu Lei ◽  
Richard Hearn ◽  
Bena Smith ◽  
...  
Keyword(s):  
Yangtze River ◽  
The Yangtze River ◽  
River Floodplain

scholarly journals Phylogenetic and Functional Traits Verify the Combined Effect of Deterministic and Stochastic Processes in the Community Assembly of Temperate Forests along an Elevational Gradient

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 591
Author(s):  
Wensong Zhou ◽  
Yuxin Zhang ◽  
Shuang Zhang ◽  
Basil N. Yakimov ◽  
Keming Ma
Keyword(s):  
Stochastic Processes ◽  
Functional Traits ◽  
Community Assembly ◽  
Woody Plants ◽  
Elevational Gradient ◽  
Combined Effect ◽  
Abiotic Environment ◽  
Spatial Factors ◽  
Assembly Mechanism ◽  
Deterministic Processes

Explaining community assembly mechanisms along elevational gradients dominated by deterministic processes or stochastic processes is a pressing challenge. Many studies suggest that phylogenetic and functional diversity are significant indicators of the process. In this study, we analyzed the structure and beta diversity of phylogenetic and functional traits along an elevational gradient and discussed the effects of environmental and spatial factors. We found that the phylogenetic and functional traits showed inconsistent changes, and their variations were closely related to the abiotic environment. The results suggested that the community assembly of woody plants was obviously affected by the combined effect of deterministic processes and the stochastic hypothesis (primarily by the latter). Phylogenetic and functional traits had a certain relationship but changed according to different rules. These results enhance our understanding of the assembly mechanism of forest communities by considering both phylogenetic and functional traits.

scholarly journals Aboveground and belowground arthropod communities experience different relative influences of stochastic and deterministic assembly processes following disturbance

2016 ◽  
Author(s):  
Scott Ferrenberg ◽  
Alexander S. Martinez ◽  
Akasha M. Faist
Keyword(s):  
Community Structure ◽  
Stochastic Processes ◽  
Community Assembly ◽  
Tree Mortality ◽  
Species Turnover ◽  
Mineral Soil ◽  
Relative Influence ◽  
Subalpine Forest ◽  
Arthropod Community ◽  
Arthropod Communities

Background. Understanding patterns of biodiversity is a longstanding challenge in ecology. Similar to other biotic groups, arthropod community structure can be shaped by deterministic and stochastic processes, with limited understanding of what moderates the relative influence of these processes. Disturbances have been noted to alter the relative influence of deterministic and stochastic processes on community assembly in various study systems, implicating ecological disturbances as a potential moderator of these forces. Methods. Using a disturbance gradient along a 5-year chronosequence of insect-induced tree mortality in a subalpine forest of the southern Rocky Mountains, Colorado, USA, we examined changes in community structure and relative influences of deterministic and stochastic processes in the assembly of aboveground (surface and litter-active species) and belowground (species active in organic and mineral soil layers) arthropod communities. Arthropods were sampled for all years of the chronosequence via pitfall traps (aboveground community) and modified Winkler funnels (belowground community) and sorted to morphospecies. Community structure of both communities were assessed via comparisons of morphospecies diversity and assemblages. Assembly processes were inferred from a mixture of linear models and matrix correlations testing for community associations with environmental properties, and from null-deviation models calculated from observed vs. expected levels of species turnover (Beta diversity) among samples. Results. Tree mortality altered community structure in both aboveground and belowground arthropod communities, but null models suggested that aboveground communities experienced greater relative influences of deterministic processes, while the relative influence of stochastic processes increased for belowground communities. Additionally, Mantel tests and linear regression models revealed significant associations between the aboveground arthropod communities and vegetation and soil properties, but no significant association among belowground arthropod communities and environmental factors. Discussion. Our results suggest context-dependent influences of stochastic and deterministic community assembly processes across different fractions of a ground-dwelling arthropod community following a disturbance. This variation in assembly may be linked to contrasting ecological strategies and dispersal rates within above- and below-ground communities. Our findings add to a growing body of evidence indicating concurrent influences of different processes in community assembly, and highlight the need to consider potential variation across different fractions of biotic communities when testing community ecology theory.

Experimental culling of minnows suppresses cyanobacterial bloom under low-nutrient conditions

2019 ◽  
Vol 76 (11) ◽  
pp. 2102-2109 ◽  
Author(s):  
Blake R. Stuparyk ◽  
Mark Graham ◽  
Jenna Cook ◽  
Mitchell A. Johnsen ◽  
Karen K. Christensen-Dalsgaard ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Trophic Cascade ◽  
Phytoplankton Biomass ◽  
Management Practices ◽  
Phytoplankton Community ◽  
Cyanobacterial Bloom ◽  
Nutrient Status ◽  
Cyanobacterial Blooms ◽  
Phytoplankton Blooms ◽  
Cascade Effect

Cyanobacterial blooms in lakes of low nutrient status are recent ecological surprises. Culling of planktivorous fish may help suppress phytoplankton blooms via a trophic cascade effect. To test this hypothesis, we conducted a 90-day experiment adjacent to a shallow oligomesotrophic lake increasingly beset by midsummer cyanobacterial blooms in the presence of high abundances of minnows and sparse herbivorous zooplankton. The single-factor (± three spottail shiners, Notropis hudsonius) experimental design was replicated 10 times for a total of twenty 1200 L capacity mesocosms. Contrary to the trophic cascade hypothesis, minnow removal decreased the abundance of bosminids capable of grazing cyanobacteria. Nevertheless, removal of the minnows significantly both suppressed phytoplankton biomass and offset the development of cyanobacteria, such as Gloeotrichia echinulata. Lower concentrations of phosphorus and nitrogen in the fishless relative to stocked mesocosms best explained these differences in the phytoplankton community. Our findings highlight how fisheries management practices that enhance minnow populations in lakes of low productivity may inadvertently contribute to cyanobacterial blooms through increased nutrient cycling.

scholarly journals Global pattern of phytoplankton diversity driven by temperature and environmental variability

2019 ◽  
Vol 5 (5) ◽  
pp. eaau6253 ◽  
Author(s):  
Damiano Righetti ◽  
Meike Vogt ◽  
Nicolas Gruber ◽  
Achilleas Psomas ◽  
Niklaus E. Zimmermann
Keyword(s):  
Species Richness ◽  
Environmental Variability ◽  
Species Turnover ◽  
Marine Phytoplankton ◽  
Marine Biodiversity ◽  
Phytoplankton Species ◽  
Global Pattern ◽  
Phytoplankton Diversity ◽  
Biogeographic Patterns ◽  
Theoretical Predictions

Despite their importance to ocean productivity, global patterns of marine phytoplankton diversity remain poorly characterized. Although temperature is considered a key driver of general marine biodiversity, its specific role in phytoplankton diversity has remained unclear. We determined monthly phytoplankton species richness by using niche modeling and >540,000 global phytoplankton observations to predict biogeographic patterns of 536 phytoplankton species. Consistent with metabolic theory, phytoplankton richness in the tropics is about three times that in higher latitudes, with temperature being the most important driver. However, below 19°C, richness is lower than expected, with ~8°– 14°C waters (~35° to 60° latitude) showing the greatest divergence from theoretical predictions. Regions of reduced richness are characterized by maximal species turnover and environmental variability, suggesting that the latter reduces species richness directly, or through enhancing competitive exclusion. The nonmonotonic relationship between phytoplankton richness and temperature suggests unanticipated complexity in responses of marine biodiversity to ocean warming.

Stochastic processes dominate marine free-living Vibrio community assembly in a subtropical gulf

2020 ◽  
Vol 96 (11) ◽  
Author(s):  
Nan Li ◽  
Ke Dong ◽  
Gonglingxia Jiang ◽  
Jinli Tang ◽  
Qiangsheng Xu ◽  
...  
Keyword(s):  
Stochastic Processes ◽  
Trophic State ◽  
Heterotrophic Bacteria ◽  
Variation Partitioning ◽  
Geographic Distance ◽  
Alpha Diversity ◽  
Mantel Test ◽  
Beibu Gulf ◽  
Assembly Features ◽  
Marine Environmental

ABSTRACT Understanding the effects of eutrophication on heterotrophic bacteria, a primary responder to eutrophication, is critical for predicting the responses of ecosystems to marine environmental pollution. Vibrio are indigenous in coastal water and of significance to geochemical cycling and public health. In this study, we investigated the diversity and assembly features of Vibrio, as well as their relationship with the environmental factors in the subtropical Beibu Gulf. We found that the alpha diversity of Vibrio increased in parallel with the trophic state they occupy. A Mantel test indicated that the trophic state was correlated to Vibrio beta diversity and the correlation gradually strengthened at higher trophic states. Variation partitioning analysis suggested that the geographic distance was an important factor impacting the variables of Vibrio communities in all the samples, but nutrients exerted more influence in the more highly eutrophic samples. Our results demonstrated that stochastic processes govern the turnover of marine Vibrio communities in the Beibu Gulf and that ecological drift was the most important process for assembly of the Vibrio communities.

scholarly journals Multiscale effects of habitat and surrounding matrices on waterbird diversity in the Yangtze River Floodplain

2020 ◽  
Author(s):  
Boyu Gao ◽  
Peng Gong ◽  
Wenyuan Zhang ◽  
Jun Yang ◽  
Yali Si
Keyword(s):  
Yangtze River ◽  
Structural Features ◽  
Ordinary Least Squares ◽  
Habitat Connectivity ◽  
The Yangtze River ◽  
Least Squares Regression ◽  
Spatial Error ◽  
River Floodplain ◽  
Surrounding Landscape ◽  
Shape Complexity

Abstract Context With the expansion in urbanization, understanding how biodiversity responds to the altered landscape becomes a major concern. Most studies focus on habitat effects on biodiversity, yet much less attention has been paid to surrounding landscape matrices and their joint effects. Objective We investigated how habitat and landscape matrices affect waterbird diversity across scales in the Yangtze River Floodplain, a typical area with high biodiversity and severe human-wildlife conflict. Methods The compositional and structural features of the landscape were calculated at fine and coarse scales. The ordinary least squares regression model was adopted, following a test showing no significant spatial autocorrelation in the spatial lag and spatial error models, to estimate the relationship between landscape metrics and waterbird diversity. Results Well-connected grassland and shrub surrounded by isolated and regular-shaped developed area maintained higher waterbird diversity at fine scales. Regular-shaped developed area and cropland, irregular-shaped forest, and aggregated distribution of wetland and shrub positively affected waterbird diversity at coarse scales. Conclusions Habitat and landscape matrices jointly affected waterbird diversity. Regular-shaped developed area facilitated higher waterbird diversity and showed the most pronounced effect at coarse scales. The conservation efforts should not only focus on habitat quality and capacity, but also habitat connectivity and complexity when formulating development plans. We suggest planners minimize the expansion of the developed area into critical habitats and leave buffers to maintain habitat connectivity and shape complexity to reduce the disturbance to birds. Our findings provide important insights and practical measures to protect biodiversity in human-dominated landscapes.

scholarly journals Marine Cyanophages Demonstrate Biogeographic Patterns throughout the Global Ocean

2014 ◽  
Vol 81 (1) ◽  
pp. 441-452 ◽  
Author(s):  
Sijun Huang ◽  
Si Zhang ◽  
Nianzhi Jiao ◽  
Feng Chen
Keyword(s):  
Strong Correlation ◽  
Multivariate Analyses ◽  
Distribution Patterns ◽  
Mantel Test ◽  
Global Ocean ◽  
Broad Host Range ◽  
Content Type ◽  
Biogeographic Patterns ◽  
Phylogenetic Lineages ◽  
Distinct Distribution

ABSTRACTMyoviruses and podoviruses that infect cyanobacteria are the two major groups of marine cyanophages, but little is known of how their phylogenetic lineages are distributed in different habitats. In this study, we analyzed the phylogenetic relationships of cyanopodoviruses and cyanomyoviruses based on the existing genomes. The 28 cyanomyoviruses were classified into four clusters (I to IV), and 19 of the 20 cyanopodoviruses were classified into two clusters, MPP-A and MPP-B, with four subclusters within cluster MPP-B. These genomes were used to recruit cyanophage-like fragments from microbial and viral metagenomes to estimate the relative abundances of these cyanophage lineages. Our results showed that cyanopodoviruses and cyanomyoviruses are both abundant in various marine environments and that clusters MPP-B, II and III appear to be the most dominant lineages. Cyanopodoviruses and cluster I and IV cyanomyoviruses exhibited habitat-related variability in their relative levels of abundance, while cluster II and III cyanomyoviruses appeared to be consistently dominant in various habitats. Multivariate analyses showed that reads that mapped toSynechococcusphages andProchlorococcusphages had distinct distribution patterns that were significantly correlated to those ofSynechococcusandProchlorococcus, respectively. The Mantel test also revealed a strong correlation between the community compositions of cyanophages and picocyanobacteria. Given that cyanomyoviruses tend to have a broad host range and some can cross-infectSynechococcusandProchlorococcus, while cyanopodoviruses are commonly host specific, the observation that their community compositions both correlated significantly with that of picocyanobacteria was unexpected. Although cyanomyoviruses and cyanopodoviruses differ in host specificity, their biogeographic distributions are likely both constrained by the picocyanobacterial community.

Integrated biogeography and assembly process of planktonic and sedimentary bacterial communities in the Yangtze River

2020 ◽  
Author(s):  
Tang Liu ◽  
Jiawen Wang ◽  
Shufeng Liu ◽  
Qian Chen ◽  
Chunmiao Zheng ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Yangtze River ◽  
Selection Process ◽  
Anthropogenic Impacts ◽  
Spatiotemporal Pattern ◽  
Assembly Process ◽  
The Yangtze River ◽  
Species Sorting ◽  
Biogeographic Patterns ◽  
Water And Sediment

<p>Bacterial communities are essential to the biogeochemical cycle in riverine ecosystems. However, the integrated biogeography and assembly process of planktonic and sedimentary bacterial communities in large rivers is still poorly understood. Here, the study provided the spatiotemporal pattern of bacterial communities in the Yangtze River of 4300 km continuum, which is the largest river in Asia. We found that the taxa in sediments are the main contributors to the bacterial diversity of the river ecosystem since sediments sub-group took 98.8% of the total 38, 904 Operational Taxonomic Units (OTUs) observed in 280 samples. Seasonal differences in bacterial communities were statistically significant in water, whereas bacterial communities in both water and sediment were geographically clustered according to five types of landforms: mountain, foothill, basin, foothill-mountain, and plain. Interestingly, the presence of two huge dams resulted in a drastic fall of bacterial taxa in sediment immediately downstream due to severe riverbed scouring. The integrity of the biogeography was satisfactorily interpreted by the combination of neutral and species sorting perspectives in meta-community theory for bacterial communities in flowing water and sediment. Although deterministic process had dominant influence on assembly processes in water and sediment communities, homogeneous selection was the main contributor in water, while combination of homogeneous selection and variable selection contributed selection process in sediment. In addition, homogenizing dispersal played more important role in community assembly process in sediment than water. Our study fills a gap in understanding of biogeography and assembly process of bacterial communities in one of the world’s largest river and highlights the importance of both planktonic and sedimentary communities to the integrity of bacterial biogeographic patterns in a river subject to varying natural and anthropogenic impacts.</p>

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