scholarly journals Bottom Communities and Abiotic Factors: Analysis of Statistical Relationship Using the Instability Index and Virtual Species Distribution

2021 ◽  
pp. 119-132
Author(s):  
Tatiana D. Zinchenko ◽  
Vladimir K. Shitikov ◽  
Larisa V. Golovatyuk
Keyword(s):  
Environmental Factors ◽  
Information Gain ◽  
Abiotic Factors ◽  
Multidimensional Data ◽  
Species Structure ◽  
Instability Index ◽  
Aquatic Communities ◽  
Abiotic Variables ◽  
Virtual Species ◽  
Instability Indices

Statistical procedures for quantifying the relationships between the community structure and abiotic variables start with selecting a minimum set of uncorrelated environmental factors that determine the ecological conditions essential for each of the species. This is especially important when constructing models of spatial distribution of species which are key to ecology of communities and conservation of nature. The aim of the study is to explore whether some applications of information theory can be used to rank environmental factors with respect to their contribution to the formation of the ecological structure of aquatic communities. We consider the applicability of the instability index, which is a special case of the Kullback-Leibler entropy divergence and reflects the information gain from the displacement of a particular realization of a random variable relative to its mean value. Using of instability indices allows to reduce multidimensional data sets on species structure of communities and abiotic factors to lower dimension sets of commensurate standardized variables and to explore the relationships between the latter. The initial data we used were the results of the long-term (1990–2019) hydrobiological survey of benthic communities in small and medium-sized rivers in the Middle and Lower Volga regions. We consider the indices of instability calculated for each of 147 taxa of macrozoobenthos and 8 geophysical and hydrochemical indicators. Based on these data, we constructed random forest regression models and calculated potential weights of environmental factors that determine ecological preferences of species. The most significant explanatory variables were used to construct distribution maps of «virtual species», which were compared with the corresponding empirical data. A habitat suitability map of chironomids (Diptera, Chironomidae), the Prodiamesinae subfamily, is presented. Instability indices can be effectively used for exploratory analysis of various ecosystems, e. g. ranking habitats according to the degree of environmental instability and / or species associations, selecting the most informative abiotic variables that determine the population density of the taxa, etc.

scholarly journals Effect of Environmental Factors on the Germination and Emergence of Drunken Horse Grass (Achnatherum inebrians)

Weed Science ◽  
2020 ◽  
pp. 1-29
Author(s):  
Yonghuan Yue ◽  
Guili Jin ◽  
Weihua Lu ◽  
Ke Gong ◽  
Wanqiang Han ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Abiotic Factors ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Germination Percentage ◽  
Western China ◽  
Burial Depth ◽  
Achnatherum Inebrians ◽  
Water Ph

Abstract Drunken horse grass [Achnatherum inebrians (Hance) Keng] is a perennial poisonous weed in western China. A comprehensive understanding of the ecological response of A. inebrians germination to environmental factors would facilitate the formulation of better management strategies for this weed. Experiments were conducted under laboratory conditions to assess the effects of various abiotic factors, including temperature, light, water, pH and burial depth, on the seed germination and seedling emergence of A. inebrians. The seeds germinated at constant temperatures of 15, 20, 25, 30, 35°C and in alternating-temperature regimes of 15/5, 20/10, 25/15, 30/20, 35/25, 40/30°C, and the seed germination percentages under constant and alternating temperatures ranged from 51% to 94% and 15% to 93%, respectively. Maximum germination occurred at a constant temperature of 25°C, and germination was prevented at 45/35°C. Light did not appear to affect seed germination. The germination percentage of seeds was more than 75% in the pH range of 5 to 10, with the highest germination percentage at pH 6. The seeds germinated at osmotic potentials of 0 MPa to -1.0 MPa, but decreasing osmotic potential inhibited germination, with no germination at -1.2MPa. After 21 d of low osmotic stress, the seeds that did not germinate after rehydration had not lost their vitality. The seedling emergence percentage was highest (90%) when seeds were buried at 1 cm but declined with increasing burial depth and no emergence at 9 cm. Deep tillage may be effective in limiting the seed germination and emergence of this species. The results of this study provide useful information on the conditions necessary for A. inebrians germination and provide a theoretical basis for science-based prediction, prevention and control of this species.

scholarly journals Longitudinal sampling of external mucosae in farmed European seabass reveals the impact of water temperature on bacterial dynamics

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Daniela Rosado ◽  
Raquel Xavier ◽  
Jo Cable ◽  
Ricardo Severino ◽  
Pedro Tarroso ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Microbial Diversity ◽  
Water Temperature ◽  
Abiotic Factors ◽  
Seasonal Effect ◽  
Microbial Composition ◽  
Surrounding Water ◽  
European Seabass ◽  
And Function ◽  
The Impact

AbstractFish microbiota are intrinsically linked to health and fitness, but they are highly variable and influenced by both biotic and abiotic factors. Water temperature particularly limits bacterial adhesion and growth, impacting microbial diversity and bacterial infections on the skin and gills. Aquaculture is heavily affected by infectious diseases, especially in warmer months, and industry practices often promote stress and microbial dysbiosis, leading to an increased abundance of potentially pathogenic bacteria. In this regard, fish mucosa health is extremely important because it provides a primary barrier against pathogens. We used 16 rRNA V4 metataxonomics to characterize the skin and gill microbiota of the European seabass, Dicentrarchus labrax, and the surrounding water over 12 months, assessing the impact of water temperature on microbial diversity and function. We show that the microbiota of external mucosae are highly dynamic with consistent longitudinal trends in taxon diversity. Several potentially pathogenic genera (Aliivibrio, Photobacterium, Pseudomonas, and Vibrio) were highly abundant, showing complex interactions with other bacterial genera, some of which with recognized probiotic activity, and were also significantly impacted by changes in temperature. The surrounding water temperature influenced fish microbial composition, structure and function over time (days and months). Additionally, dysbiosis was more frequent in warmer months and during transitions between cold/warm months. We also detected a strong seasonal effect in the fish microbiota, which is likely to result from the compound action of several unmeasured environmental factors (e.g., pH, nutrient availability) beyond temperature. Our results highlight the importance of performing longitudinal studies to assess the impact of environmental factors on fish microbiotas.

scholarly journals Temporal variation of the phytoplankton community at short sampling intervals in the Mundaú reservoir, Northeastern Brazil

2008 ◽  
Vol 22 (4) ◽  
pp. 970-982 ◽  
Author(s):  
Ênio Wocyli Dantas ◽  
Ariadne do Nascimento Moura ◽  
Maria do Carmo Bittencourt-Oliveira ◽  
João Dias de Toledo Arruda Neto ◽  
Airlton de Deus C. Cavalcanti
Keyword(s):  
Phytoplankton Community ◽  
Abiotic Factors ◽  
Distribution Patterns ◽  
Northeastern Brazil ◽  
Cylindrospermopsis Raciborskii ◽  
Algae Biomass ◽  
Dissolved Phosphorus ◽  
Sampling Intervals ◽  
Abiotic Variables ◽  
Dry And Rainy Seasons

The aim of this study was to determine how abiotic factors drive the phytoplankton community in a water supply reservoir within short sampling intervals. Samples were collected at the subsurface (0.1 m) and bottom of limnetic (8 m) and littoral (2 m) zones in both the dry and rainy seasons. The following abiotic variables were analyzed: water temperature, dissolved oxygen, electrical conductivity, total dissolved solids, turbidity, pH, total nitrogen, nitrite, nitrate, total phosphorus, total dissolved phosphorus and orthophosphate. Phytoplankton biomass was determined from biovolume values. The role abiotic variables play in the dynamics of phytoplankton species was determined by means of Canonical Correspondence Analysis. Algae biomass ranged from 1.17×10(4) to 9.21×10(4) µg.L-1; cyanobacteria had biomass values ranging from 1.07×10(4) to 8.21×10(4) µg.L-1. High availability of phosphorous, nitrogen limitation, alkaline pH and thermal stability all favored cyanobacteria blooms, particularly during the dry season. Temperature, pH, total phosphorous and turbidity were key factors in characterizing the phytoplankton community between sampling times and stations. Of the species studied, Cylindrospermopsis raciborskii populations were dominant in the phytoplankton in both the dry and rainy seasons. We conclude that the phytoplankton was strongly influenced by abiotic variables, particularly in relation to seasonal distribution patterns.

scholarly journals Ecology of China's pilot cities for creating healthy aquatic communities: heterogeneity, niches and environmental factors

2019 ◽  
Vol 70 (5) ◽  
pp. 611
Author(s):  
Changsen Zhao ◽  
Shengtian Yang
Keyword(s):  
Environmental Factors ◽  
Critical Issue ◽  
Research Front ◽  
Ecological Communities ◽  
Aquatic Communities ◽  
Resources Management ◽  
Ecological Resources ◽  
Developing Cities ◽  
Stress Changes ◽  
Theoretical Evidence

Globally, climate change and human activities have greatly stressed the health of water ecological communities (WECs) in cities, and WEC restoration is therefore a critical issue, especially for developing cities. To restore healthy WECs and support humans into the future, the Ministry of Water Resources, China, proposed a project to build cities with healthy WECs. Jinan was designated the first pilot city for this project. The exploration of methodologies on WEC restoration in pilot cities is important because it can provide reliable theoretical evidence and methodological references for researchers and managers, and serve as an important decision-making basis for ecological resources management and remediation of fresh waters. In this Research Front, we have brought together studies on aquatic ecosystems of the first pilot cities project to build healthy WECs in China, including studies on the health, temporospatial heterogeneity and niches of WECs, as well as environmental factors. These studies can significantly increase our understanding of the ecology of the aquatic systems in China’s pilot cities. It is anticipated that this ecosystem knowledge will help assess the effects of climate- and human-induced stress changes, and form the basis for making aquatic ecosystem protection and restoration decisions across the globe.

scholarly journals Biology, not environment, drives major patterns in maximum tetrapod body size through time

2012 ◽  
Vol 8 (4) ◽  
pp. 674-677 ◽  
Author(s):  
Roland B. Sookias ◽  
Roger B. J. Benson ◽  
Richard J. Butler
Keyword(s):  
Body Size ◽  
Environmental Factors ◽  
Abiotic Factors ◽  
Logistic Models ◽  
Growth Curves ◽  
Maximum Size ◽  
Generalized Least Squares ◽  
Least Squares Regression ◽  
Geological Time ◽  
Cenozoic Mammals

Abiotic and biological factors have been hypothesized as controlling maximum body size of tetrapods and other animals through geological time. We analyse the effects of three abiotic factors—oxygen, temperature and land area—on maximum size of Permian–Jurassic archosauromorphs and therapsids, and Cenozoic mammals, using time series generalized least-squares regression models. We also examine maximum size growth curves for the Permian–Jurassic data by comparing fits of Gompertz and logistic models. When serial correlation is removed, we find no robust correlations, indicating that these environmental factors did not consistently control tetrapod maximum size. Gompertz models—i.e. exponentially decreasing rate of size increase at larger sizes—fit maximum size curves far better than logistic models. This suggests that biological limits such as reduced fecundity and niche space availability become increasingly limiting as larger sizes are reached. Environmental factors analysed may still have imposed an upper limit on tetrapod body size, but any environmentally imposed limit did not vary substantially during the intervals examined despite variation in these environmental factors.

scholarly journals Congregating behavior and response to resource distribution of the Green House Millipede, Oxidus gracilis

2016 ◽  
Author(s):  
Gregory Bulpitt
Keyword(s):  
Environmental Factors ◽  
Abiotic Factors ◽  
Environmental Parameters ◽  
Field Recording ◽  
Litter Cover ◽  
Rock Cover ◽  
Oxidus Gracilis ◽  
Experimental Trials ◽  
And Behavior ◽  
Number Of Individuals

Background. Congregating behaviors, though common among many animal species, are little studied among millipedes. It is also unclear to what extent abiotic factors influence the distribution and behavior of millipedes. The species Oxidus gracilis was surveyed around several streams on the island of Mo’orea along with soil moisture, leaf litter cover, and rock cover. Experiments were designed in order to determine how an innate congregating behavior may affect their distributions. Methods. Fifteen transects were performed in the field, recording O. gracilis abundances and the three environmental factors every 1 m. Forty trials were performed using covered bins filled with soil and five fruits of the Tahitian chestnut tree (Inocarpus fagifer). Ten millipedes were placed in the box and left for an hour, after which the number of individuals per fruit was recorded. Results. It was found that while none of the three environmental factors were strong indicators of the distribution of O. gracilis , individuals did in fact demonstrate a tendency to congregate in the experimental trials. Discussion. The lack of significant relationships with the three environmental parameters suggests a generalist behavior of this millipede species, potentially benefitting its invasive nature. The congregating behavior could potentially be for the purposes of mating or defense. Although not studied in this paper, it is possible that conspecific chemical cues are responsible.

scholarly journals Terpenoid indole alkaloid biosynthesis in Catharanthus roseus: effects and prospects of environmental factors in metabolic engineering

2021 ◽  
Vol 43 (11) ◽  
pp. 2085-2103
Author(s):  
Yongliang Liu ◽  
Barunava Patra ◽  
Sanjay Kumar Singh ◽  
Priyanka Paul ◽  
Yan Zhou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Metabolic Engineering ◽  
Environmental Factors ◽  
Catharanthus Roseus ◽  
Abiotic Factors ◽  
Indole Alkaloids ◽  
Indole Alkaloid ◽  
Terpenoid Indole Alkaloids ◽  
Madagascar Periwinkle ◽  
Specialized Metabolites

Abstract Plants synthesize a vast array of specialized metabolites that primarily contribute to their defense and survival under adverse conditions. Many of the specialized metabolites have therapeutic values as drugs. Biosynthesis of specialized metabolites is affected by environmental factors including light, temperature, drought, salinity, and nutrients, as well as pathogens and insects. These environmental factors trigger a myriad of changes in gene expression at the transcriptional and posttranscriptional levels. The dynamic changes in gene expression are mediated by several regulatory proteins that perceive and transduce the signals, leading to up- or down-regulation of the metabolic pathways. Exploring the environmental effects and related signal cascades is a strategy in metabolic engineering to produce valuable specialized metabolites. However, mechanistic studies on environmental factors affecting specialized metabolism are limited. The medicinal plant Catharanthus roseus (Madagascar periwinkle) is an important source of bioactive terpenoid indole alkaloids (TIAs), including the anticancer therapeutics vinblastine and vincristine. The emerging picture shows that various environmental factors significantly alter TIA accumulation by affecting the expression of regulatory and enzyme-encoding genes in the pathway. Compared to our understanding of the TIA pathway in response to the phytohormone jasmonate, the impacts of environmental factors on TIA biosynthesis are insufficiently studied and discussed. This review thus focuses on these aspects and discusses possible strategies for metabolic engineering of TIA biosynthesis. Purpose of work Catharanthus roseus is a rich source of bioactive terpenoid indole alkaloids (TIAs). The objective of this work is to present a comprehensive account of the influence of various biotic and abiotic factors on TIA biosynthesis and to discuss possible strategies to enhance TIA production through metabolic engineering.

scholarly journals Biodiversity of Gut Microbiota: Impact of Various Host and Environmental Factors

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Haseeb Anwar ◽  
Arslan Iftikhar ◽  
Humaira Muzaffar ◽  
Ahmad Almatroudi ◽  
Khaled S. Allemailem ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Gut Microbiota ◽  
Significant Role ◽  
Abiotic Factors ◽  
Physiological Mechanisms ◽  
Microbial Species ◽  
Factors Influencing ◽  
Bacteria And Fungi ◽  
Over Time

Human bodies encompass very important symbiotic and mutualistic relationships with tiny creatures known as microbiota. Trillions of these tiny creatures including protozoa, viruses, bacteria, and fungi are present in and on our bodies. They play important roles in various physiological mechanisms of our bodies. In return, our bodies provide them with the habitat and food necessary for their survival. In this review, we comprehend the gut microbial species present in various regions of the gut. We can get benefits from microbiota only if they are present in appropriate concentrations, as if their concentration is altered, it will lead to dysbiosis of microbiota which further contributes to various health ailments. The composition, diversity, and functionality of gut microbiota do not remain static throughout life as they keep on changing over time. In this review, we also reviewed the various biotic and abiotic factors influencing the quantity and quality of these microbiota. These factors serve a significant role in shaping the gut microbiota population.

scholarly journals Spatial and temporal distribution of Pseudis minuta (Anura, Hylidae, Hylinae) and environmental variables related to its reproductive activity in Reserva Biológica do Lami, southern Brazil

2010 ◽  
Vol 100 (2) ◽  
pp. 145-150 ◽  
Author(s):  
Caroline Zank ◽  
Marcos Di-Bernardo ◽  
Raúl Maneyro ◽  
Patrick Colombo ◽  
Luciana A. Fusinatto ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Abiotic Factors ◽  
Temporal Distribution ◽  
Reproductive Activity ◽  
Spatial And Temporal Distribution ◽  
Southern Brazil ◽  
Porto Alegre ◽  
Abiotic Variables ◽  
Temperature Water ◽  
Pseudis Minuta

We studied the reproductive biology of a population of Pseudis minuta Günther, 1858 from Reserva Biológica do Lami (30º 15' S; 51º 05' W), Porto Alegre, southern Brazil. We assessed the spatial and temporal distribution of individuals (males, females, juveniles) and explored potential relationships with environmental variables. Field activities encompassed bimonthly surveys in three semi-permanent ponds, each one during approximately two days and two nights, from August 2004 to July 2005. We recorded differences in the sites used by males, females and juveniles, with males occupying deeper and more distant places from the border. The temporal distributions of individuals, calling sites and amplectant pairs indicated that the reproductive activity of P. minuta is related to some of the studied abiotic factors. Calling males presented statistical differences in relation to non-calling males for all daily abiotic variables analyzed (air temperature, water temperature, relative humidity and rainfall), as well as to monthly temperature and rainfall. The number of active males, females and juveniles was influenced by at least one of the daily or monthly environmental variables analyzed. We conclude that the reproduction in this species is seasonal and may be partially determined by abiotic factors.

scholarly journals Biotic and abiotic factors associated with soil suppressiveness to Rhizoctonia solani

2006 ◽  
Vol 63 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Raquel Ghini ◽  
Marcelo Augusto Boechat Morandi
Keyword(s):  
Abiotic Factors ◽  
Organic Matter Content ◽  
Exchange Capacity ◽  
Matter Content ◽  
Soil Samples ◽  
Fluorescein Diacetate ◽  
Soil Suppressiveness ◽  
Fluorescent Pseudomonas ◽  
Undisturbed Forest ◽  
Abiotic Variables

Crop management may modify soil characteristics, and as a consequence, alter incidence of diseases caused by soilborne pathogens. This study evaluated the suppressiveness to R. solani in 59 soil samples from a microbasin. Soil sampling areas included undisturbed forest, pasture and fallow ground areas, annual crops, perennial crops, and ploughed soil. The soil samples were characterized according to abiotic variables (pH; electrical conductivity; organic matter content; N total; P; K; Ca; Mg; Al; H; S; Na; Fe; Mn; Cu; Zn; B; cation exchange capacity; sum of bases and base saturation) and biotic variables (total microbial activity evaluated by the CO2 evolution and fluorescein diacetate hydrolysis; culturable bacterial, fungal, actinomycetes, protozoa, fluorescent Pseudomonas and Fusarium spp. communities). The contribution and relationships of these variables to suppression to R. solani were assessed by path analysis. When all samples were analyzed together, only abiotic variables correlated with suppression of R. solani, but the entire set of variables explained only 51% of the total variation. However, when samples were grouped and analyzed by vegetation cover, the set of evaluated variables in all cases accounted for more than 90% of the variation in suppression of the pathogen. In highly suppressive soils of forest and pasture/fallow ground areas, several abiotic variables and fluorescein diacetate hydrolysis correlated with suppression of R. solani and the set of variables explained more than 98% of suppressiveness.

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