scholarly journals Anthropogenic-induced environmental changes in the Nile-delta and their consequences on molluscan biodiversity and community structure

2021 ◽  
Vol 126 ◽  
pp. 107654
Author(s):  
Ahmed Awad Abdelhady
Keyword(s):  
Community Structure ◽  
Environmental Changes ◽  
Nile Delta

scholarly journals Climate change negatively impacts dominant microbes in the sediments of a High Arctic lake

2019 ◽  
Author(s):  
Graham A. Colby ◽  
Matti O. Ruuskanen ◽  
Kyra A. St. Pierre ◽  
Vincent L. St. Louis ◽  
Alexandre J. Poulain ◽  
...  
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Environmental Changes ◽  
High Arctic ◽  
The Arctic ◽  
Large Lake ◽  
Spatial Gradients ◽  
Functional Potential ◽  
High Runoff ◽  
Sediment Microbes

AbstractTemperatures in the Arctic are expected to increase dramatically over the next century, yet little is known about how microbial communities and their underlying metabolic processes will be affected by these environmental changes in freshwater sedimentary systems. To address this knowledge gap, we analyzed sediments from Lake Hazen, NU Canada. Here, we exploit the spatial heterogeneity created by varying runoff regimes across the watershed of this uniquely large lake at these latitudes to test how a transition from low to high runoff, used as one proxy for climate change, affects the community structure and functional potential of dominant microbes. Based on metagenomic analyses of lake sediments along these spatial gradients, we show that increasing runoff leads to a decrease in taxonomic and functional diversity of sediment microbes. Our findings are likely to apply to other, smaller, glacierized watersheds typical of polar or high latitude / high altitudes ecosystems; we can predict that such changes will have far reaching consequences on these ecosystems by affecting nutrient biogeochemical cycling, the direction and magnitude of which are yet to be determined.

scholarly journals Effects of Elevation and Distance from Highway on the Abundance and Community Structure of Bacteria in Soil along Qinghai-Tibet Highway

2021 ◽  
Vol 18 (24) ◽  
pp. 13137
Author(s):  
Zhuocheng Liu ◽  
Yangang Yang ◽  
Shuangxuan Ji ◽  
Di Dong ◽  
Yinruizhi Li ◽  
...  
Keyword(s):  
Community Structure ◽  
Soil Bacteria ◽  
Environmental Changes ◽  
Chemical Properties ◽  
Soil Nutrient ◽  
Nutrient Content ◽  
Tibet Plateau ◽  
Nitrifying Bacteria ◽  
Ecological Environment ◽  
The Impact

In recent years, highway construction in the Qinghai-Tibet Plateau (QTP) has developed rapidly. When the highway passes through grassland, the soil, vegetation, and ecological environment along the line are disturbed. However, the impact on soil bacteria is still unclear. Soil bacteria play an important role in the ecological environment. The Qinghai-Tibet Highway (QTH) was selected as the research object to explore the changes in bacterial community structure, vegetation, soil, and other indicators. The results showed that the highway-related activities increased the degradation of vegetation along the road, significantly changed the physical and chemical properties of soil, and caused heavy metal pollution. These environmental factors affected the diversity and community structure of soil bacteria. This kind of disturbance shows a trend of gradually increasing from near to far from the highway. Gemmatimonas, Terrimonas, Nitrospira and Bacillus are more tolerant to environmental changes along the highway, while Barnesiella, and Blastococcus are more sensitive. The content of nitrate decreased and the content of ammonium nitrogen increased in the disturbed area, increasing the abundance of nitrifying bacteria. Therefore, the main factor of the disturbance of the QTH on the grassland is the decline of soil nutrient content, and the supplement of soil nutrients such as carbon and nitrogen should be taken into account in the process of ecological restoration of grassland along the line.

scholarly journals STUDI KEANEKARAGAMAN DAN STRUKTUR KOMUNITAS PERIFITON DI PERAIRAN SUNGAI COBAN RONDO MALANG

2020 ◽  
Vol 1 (2) ◽  
pp. 93-97
Author(s):  
Zainal Abidin
Keyword(s):  
Water Quality ◽  
Cluster Analysis ◽  
Community Structure ◽  
Environmental Changes ◽  
Aquatic Organisms ◽  
Dominance Index ◽  
Periphyton Community ◽  
Similarity Indices ◽  
And Cluster Analysis ◽  
Index Value

Periphyton is a community of microorganisms that live attached to or adjacent to a substrate sink. For aquatic organisms, periphyton habitats have a relatively fixed. With it is so, the changes of water quality and substrate greatly affects the composition of his life and abundance. Periphyton composition and abundance depends on the tolerance or sensitivity to environmental changes. This study aims to determine each periphyton community in responding to changes in habitat quality by way of adjustment in community structure. The methodology used in this prektikum involves taking data from four stations along the river Coban Rondo, in each station there are 3 replicates. And take measurements of factors such environments as supportive data turbidity, flow rate, pH, and depth. Analyzed using Simpson's Dominance Index to determine the type of periphyton dominance, as well as morisita similarity indices and cluster analysis. The results showed that the diversity in each station belonging to the category of high (H more than 3.32) because the obtained value of the index H' between 3.2 to 3.48. Species that dominate from the four stations is Pinularia with an average Index Value Important (IVI) 31,5.

scholarly journals Early-middle Holocene climatic and environmental changes in the Nile delta and implications for early agriculture

2018 ◽  
Vol 30 (3) ◽  
pp. 857-864
Author(s):  
HADEER Sheashaa ◽  
◽  
ZHAO Xiaoshuang ◽  
ALAA Salem ◽  
LIU Yan ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Nile Delta ◽  
Early Agriculture ◽  
Middle Holocene

scholarly journals Short Communication: Community structure and diversity of Odonata in Suranadi Natural Park, West Lombok Indonesia

2020 ◽  
Vol 21 (2) ◽  
Author(s):  
MOHAMMAD LIWA ILHAMDI ◽  
AGIL AL IDRUS ◽  
DIDIK SANTOSO ◽  
Gito Hadiprayitno
Keyword(s):  
Community Structure ◽  
Data Collection ◽  
Short Communication ◽  
Environmental Changes ◽  
Diversity Index ◽  
Scientific Information ◽  
Ecosystem Change ◽  
Survey Method ◽  
Transect Line ◽  
Natural Park

Abstract. Ilhamdi ML, Al Idrus A, Santoso D, Hadiprayitno G. 2020. Short Communication: Community structure and diversity of Odonata in Suranadi Natural Park, West Lombok Indonesia. Biodiversitas 21: 718-723. Odonata is an order of insects. The life cycle of this order is dependent on freshwater habitat. Sensitivity to environmental changes causes odonates to be important bioindicators of ecosystem change. The importance of the ecological role of odonates is not followed by adequate scientific information on Odonata communities, especially in the Suranadi Natural Park (SNP). The study aimed to monitor the existence and community structure of Odonata in the SNP area every six months in period. The data collection technique was using a survey method by following the transect line, namely the waterway transect line (WTL), plantation border transect (PT) and settlement border transect (ST). Data collection was done 4 times from April to May 2019, once every 2 weeks. The sampling was done twice in the morning from 08.00 to 11.00 AM and in the afternoon from 03.00 to 05.00 PM. Data were analyzed using the relative frequency equation and Diversity Index. The results showed that there were 16 species of odonates consisting of the family Libellulidae (11 species), Platycnemididae (1 species), Chlorocyphidae (1 species), and Coegrinidae (3 species). Orthetrum sabina, Neurothemis ramburii, Diplacodes trivialis, Gynacantha subinterrupta, Copera marginipes, and Pantala flavescens, are species that are present in all of each observation sites. The waterway transect has the highest diversity index (2.027), followed by settlement transect (1.367), and the lowest is plantation transect (1.131).

scholarly journals Diversity and distribution of heterotrophic flagellates in seawater of the Powell Basin, Antarctic Peninsula

2021 ◽  
Vol 40 ◽  
Author(s):  
Zhiyi Chen ◽  
Jianfeng He ◽  
Shunan Cao ◽  
Zhibo Lu ◽  
Musheng Lan ◽  
...  
Keyword(s):  
Community Structure ◽  
Environmental Factors ◽  
Antarctic Peninsula ◽  
Environmental Changes ◽  
Bacterial Biomass ◽  
Heterotrophic Nanoflagellates ◽  
Heterotrophic Flagellates ◽  
Polar Regions ◽  
Biological Interactions ◽  
Essential Components

Heterotrophic flagellates are essential components of the marine microbial food web. However, how the changes in flagellate populations reflect environmental changes in marine ecosystems is still unclear, especially in polar regions. In this study, we used pyrosequencing to examine the community structure of heterotrophic flagellates (HFs) in the Powell Basin’s surface waters of the northern Antarctic Peninsula. OTUs (operational taxonomic units) of different taxa and the correlations between community structure and environmental factors were analysed. Eight taxa of HFs were selected for the principal analysis: Telonemia, Picozoa, Rhizaria, Amoebozoa, Apusomonas, Centrohelida, Choanomonada and marine stramenopiles (MASTs). The HFs were defined as heterotrophic picoflagellates (HPFs; <3 μm) and heterotrophic nanoflagellates (HNFs; >3 μm, <20 μm), which had similar dominant phyla (MASTs and Telonemia). However, their taxonomic composition differed. Environmental factors exerted similar effects on the community structure of both HPFs and HNPs. Compared with the correlation between HPF and environmental factors, the correlation between HNF and environmental factors was stronger. Salinity, bacterial biomass and the biological interactions amongst dominant taxa were the main variables to influence the diversity and community structure of HFs.

scholarly journals Changes in Heterotrophic Picoplankton Community Structure after Induction of a Phytoplankton Bloom under Different Light Regimes

Diversity ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 195 ◽  
Author(s):  
Karayanni ◽  
Kormas ◽  
Moustaka-Gouni ◽  
Sommer
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Relative Abundance ◽  
Environmental Changes ◽  
Phytoplankton Bloom ◽  
Phytoplankton Growth ◽  
Light Regimes ◽  
Operational Taxonomic Units ◽  
Abundant Otus

Bacterial and archaeal diversity and succession were studied during a mesocosm experiment that investigated whether changing light regimes could affect the onset of phytoplankton blooms. For this, 454-pyrosequencing of the bacterial V1-V3 and archaeal V3-V9 16S rRNA regions was performed in samples collected from four mesocosms receiving different light irradiances at the beginning and the end of the experiment and during phytoplankton growth. In total, 46 bacterial operational taxonomic units (OTUs) with ≥1% relative abundance occurred (22–34 OTUs per mesocosm). OTUs were affiliated mainly with Rhodobacteraceae, Flavobacteriaceae and Alteromonadaceae. The four mesocosms shared 11 abundant OTUs. Dominance increased at the beginning of phytoplankton growth in all treatments and decreased thereafter. Maximum dominance was found in the mesocosms with high irradiances. Overall, specific bacterial OTUs had different responses in terms of relative abundance under in situ and high light intensities, and an early phytoplankton bloom resulted in different bacterial community structures both at high (family) and low (OTU) taxonomic levels. Thus, bacterial community structure and succession are affected by light regime, both directly and indirectly, which may have implications for an ecosystem’s response to environmental changes.

scholarly journals Evaluating environmental drivers of spatial variability in free-living nematode assemblages along the Portuguese margin

2017 ◽  
Vol 14 (3) ◽  
pp. 651-669 ◽  
Author(s):  
Lidia Lins ◽  
Frederik Leliaert ◽  
Torben Riehl ◽  
Sofia Pinto Ramalho ◽  
Eliana Alfaro Cordova ◽  
...  
Keyword(s):  
Community Structure ◽  
Environmental Factors ◽  
Food Availability ◽  
Environmental Changes ◽  
Shelf Break ◽  
Environmental Drivers ◽  
Continental Margins ◽  
Sediment Heterogeneity ◽  
Iberian Margin ◽  
Upper Slope

Abstract. Understanding processes responsible for shaping biodiversity patterns on continental margins is an important requirement for comprehending anthropogenic impacts in these environments and further management of biodiversity. Continental margins perform crucial functions linked to key ecological processes which are mainly structured by surface primary productivity and particulate organic matter flux to the seafloor, but also by heterogeneity in seafloor characteristics. However, to what extent these processes control local and regional biodiversity remains unclear. In this study, two isobathic parallel transects located at the shelf break (300–400 m) and upper slope (1000 m) of the western Iberian margin were used to test how food input and sediment heterogeneity affect nematode diversity independently from the spatial factors geographical distance and water depth. We also examined the potential role of connectedness between both depth transects through molecular phylogenetic analyses. Regional generic diversity and turnover were investigated at three levels: within a station, between stations from the same depth transect, and between transects. High variability in food availability and high sediment heterogeneity at the shelf-break transect were directly linked to high diversity within stations and higher variation in community structure across stations compared to the upper slope transect. Contrastingly, environmental factors (food availability and sediment) did not vary significantly between stations located at the upper slope, and this lack of differences were also reflected in a low community turnover between these deeper stations. Finally, differences in nematode communities between both transects were more pronounced than differences within each of the isobathic transects, but these changes were paralleled by the previously mentioned environmental changes. These results suggest that changes in community structure are mainly dictated by environmental factors rather than spatial differences at the western Iberian margin. Furthermore, phylogenetic relationships revealed no evidence for depth-endemic lineages, indicating regular species interchanges across different depths.

scholarly journals Empirically modelling the potential effects of changes in temperature and prey availability on the growth of cod larvae in UK shelf seas

2008 ◽  
Vol 65 (9) ◽  
pp. 1559-1572 ◽  
Author(s):  
Sophie G. Pitois ◽  
Clive J. Fox
Keyword(s):  
Community Structure ◽  
Environmental Changes ◽  
Atlantic Cod ◽  
Prey Availability ◽  
Life Stage ◽  
Larval Growth ◽  
Species Abundance ◽  
Zooplankton Community ◽  
Zooplankton Community Structure ◽  
Shelf Seas

Abstract Pitois, S. G., and Fox, C. J. 2008. Empirically modelling the potential effects of changes in temperature and prey availability on the growth of cod larvae in UK shelf seas. – ICES Journal of Marine Science, 65: 1559–1572. It has been hypothesized that changes in zooplankton community structure over the past four decades led to reduced growth and survival of prerecruit Atlantic cod (Gadus morhua) and that this was a key factor underlying poor year classes, contributing to stock collapse, and inhibiting the recovery of stocks around the UK. To evaluate whether observed changes in plankton abundance, species composition and temperature could have led to periods of poorer growth of cod larvae, we explored the effect of prey availability and temperature on early larval growth using an empirical trophodynamic model. Prey availability was parameterized using species abundance data from the Continuous Plankton Recorder. Our model suggests that the observed changes in plankton community structure in the North Sea may have had less impact on cod larval growth, at least for the first 40 days following hatching, than previously suggested. At least in the short term, environmental and prey conditions should be able to sustain growth of cod larvae and environmental changes acting on this early life stage should not limit stock recovery.

scholarly journals Modeling of the Coral Microbiome: the Influence of Temperature and Microbial Network

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Laís F. O. Lima ◽  
Maya Weissman ◽  
Micheal Reed ◽  
Bhavya Papudeshi ◽  
Amanda T. Alker ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Dynamic Model ◽  
Microbial Community Structure ◽  
Environmental Changes ◽  
Mucus Layer ◽  
Shotgun Metagenomics ◽  
Microbial Network ◽  
Coral Microbiome ◽  
Relative Abundances

ABSTRACT Host-associated microbial communities are shaped by extrinsic and intrinsic factors to the holobiont organism. Environmental factors and microbe-microbe interactions act simultaneously on the microbial community structure, making the microbiome dynamics challenging to predict. The coral microbiome is essential to the health of coral reefs and sensitive to environmental changes. Here, we develop a dynamic model to determine the microbial community structure associated with the surface mucus layer (SML) of corals using temperature as an extrinsic factor and microbial network as an intrinsic factor. The model was validated by comparing the predicted relative abundances of microbial taxa to the relative abundances of microbial taxa from the sample data. The SML microbiome from Pseudodiploria strigosa was collected across reef zones in Bermuda, where inner and outer reefs are exposed to distinct thermal profiles. A shotgun metagenomics approach was used to describe the taxonomic composition and the microbial network of the coral SML microbiome. By simulating the annual temperature fluctuations at each reef zone, the model output is statistically identical to the observed data. The model was further applied to six scenarios that combined different profiles of temperature and microbial network to investigate the influence of each of these two factors on the model accuracy. The SML microbiome was best predicted by model scenarios with the temperature profile that was closest to the local thermal environment, regardless of the microbial network profile. Our model shows that the SML microbiome of P. strigosa in Bermuda is primarily structured by seasonal fluctuations in temperature at a reef scale, while the microbial network is a secondary driver. IMPORTANCE Coral microbiome dysbiosis (i.e., shifts in the microbial community structure or complete loss of microbial symbionts) caused by environmental changes is a key player in the decline of coral health worldwide. Multiple factors in the water column and the surrounding biological community influence the dynamics of the coral microbiome. However, by including only temperature as an external factor, our model proved to be successful in describing the microbial community associated with the surface mucus layer (SML) of the coral P. strigosa. The dynamic model developed and validated in this study is a potential tool to predict the coral microbiome under different temperature conditions.

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