scholarly journals Assessing the relationship between multivariate community structure and environmental variables

1996 ◽  
Vol 143 ◽  
pp. 303-306 ◽  
Author(s):  
JAF Diniz-Filho ◽  
LM Bini
Keyword(s):  
Community Structure ◽  
Environmental Variables ◽  
The Relationship

scholarly journals Planktonic Microcrustacean Community Structure Varies with Trophic Status and Environmental Variables in Tropical Shallow Lakes in Malaysia

Diversity ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 322
Author(s):  
Wahidah Ahmad Dini Umi ◽  
Fatimah Md Yusoff ◽  
Ahmad Zaharin Aris ◽  
Zati Sharip ◽  
Artem Y. Sinev
Keyword(s):  
Community Structure ◽  
Shallow Lakes ◽  
Environmental Variables ◽  
Trophic Status ◽  
Tropical Lakes ◽  
Lake Trophic Status ◽  
Community Restructuring ◽  
Main Factors ◽  
Abundance And Diversity ◽  
The Relationship

A study was conducted to evaluate planktonic microcrustacean species composition, abundance, and diversity in lakes with different trophic status and to determine the relationship between microcrustacean community structure and lake environmental conditions. This study hypothesized that there are correlations between eutrophication levels and microcrustacean community structures in a lake. Three shallow lakes of different trophic status (Sembrong, Putrajaya and Subang lakes) were selected for this study. Two-Way Analysis of similarities (ANOSIM) revealed differences in microcrustacean diversity and density amongst lakes, where the hypereutrophic condition in Sembrong lake resulted in the lowest diversity but the highest density of microcrustaceans. Similarity percentage (SIMPER) analysis identified the discriminator species among lakes where the domination of small-sized microcrustaceans was observed in lakes with high levels of eutrophication; the hypereutrophic Sembrong lake (Ceriodaphnia cornuta, 74.0%); the meso-eutrophic Putrajaya lake (Bosmina longirostris, 46.9%; C. cornuta, 19.4%). Chlorophyll a, total phosphorus and water transparency showed significant roles in the distribution of microcrustaceans. The canonical correspondence analysis (CCA) scores indicated that small-sized C. cornuta and B. longirostris were related to the eutrophic conditions of lakes. This study elucidated that the lake trophic status could be one of the main factors contributing to the community restructuring of microcrustaceans in tropical lakes.

scholarly journals A revision of daily egg production estimation methods, with application to Atlanto-Iberian sardine. 2. Spatially and environmentally explicit estimates of egg production

2011 ◽  
Vol 68 (3) ◽  
pp. 528-536 ◽  
Author(s):  
Miguel Bernal ◽  
Yorgos Stratoudakis ◽  
Simon Wood ◽  
Leire Ibaibarriaga ◽  
Luis Valdés ◽  
...  
Keyword(s):  
Temporal Variability ◽  
Environmental Variables ◽  
Egg Production ◽  
Stock Assessment ◽  
Production Model ◽  
Estimation Methods ◽  
Statistical Framework ◽  
Spatio Temporal ◽  
The Relationship ◽  
Made In

Abstract Bernal, M., Stratoudakis, Y., Wood, S., Ibaibarriaga, L., Uriarte, A., Valdés, L., and Borchers, D. 2011. A revision of daily egg production estimation methods, with application to Atlanto-Iberian sardine. 2. Spatially and environmentally explicit estimates of egg production. – ICES Journal of Marine Science, 68: . A spatially and environmentally explicit egg production model is developed to accommodate a number of assumptions about the relationship between egg production and mortality and associated environmental variables. The general model was tested under different assumptions for Atlanto-Iberian sardine. It provides a flexible estimator of egg production, in which a range of assumptions and hypotheses can be tested in a structured manner within a well-defined statistical framework. Application of the model to Atlanto-Iberian sardine increased the precision of the egg production time-series, and allowed improvements to be made in understanding the spatio-temporal variability in egg production, as well as implications for ecology and stock assessment.

Consistency of patterns between laboratory experiments and field collected fish in otolith chemistry: an example and applications for salinity reconstructions

2005 ◽  
Vol 56 (5) ◽  
pp. 609 ◽  
Author(s):  
T. S. Elsdon ◽  
B. M. Gillanders
Keyword(s):  
Environmental Variables ◽  
Laboratory Experiments ◽  
Juvenile Fish ◽  
Otolith Chemistry ◽  
Ambient Water ◽  
Elemental Concentrations ◽  
Adequate Knowledge ◽  
Black Bream ◽  
Environmental Histories ◽  
The Relationship

Elemental concentrations within fish otoliths can track movements and migrations of fish through gradients of environmental variables. Tracking the movements of fish relies on establishing links between environmental variables and otolith chemistry, with links commonly made using laboratory experiments that rear juvenile fish. However, laboratory experiments done on juvenile fish may not accurately reflect changes in wild fish, particularly adults. We tested the hypotheses that: (1) the relationship between ambient (water) and otolith chemistry is similar between laboratory-reared black bream (Acanthopagrus butcheri) and wild black bream; and (2) ontogeny does not influence otolith chemistry. Field-collected and laboratory-reared fish showed similar effects of ambient strontium : calcium (Sr : Ca) on otolith Sr : Ca concentrations. However, ambient and otolith barium : calcium concentrations (Ba : Ca) differed slightly between laboratory-reared and field-collected fish. Importantly, fish reared in stable environmental variables showed no influence of ontogeny on Sr : Ca or Ba : Ca concentrations. Natural distributions of ambient Sr : Ca showed no clear relationship to salinity, yet, ambient Ba : Ca was inversely related to salinity. The distribution of ambient Sr : Ca and Ba : Ca in estuaries inhabited by black bream, suggest that these elements can answer different questions regarding environmental histories of fish. Reconstructing salinity histories of black bream using otolith Ba : Ca concentrations seems plausible, if adequate knowledge of Ba : Ca gradients within estuaries is obtained.

scholarly journals Monitoring studies should consider temporal variability to reveal relations between cyanobacterial abundance and environmental variables

2015 ◽  
Vol 87 (3) ◽  
pp. 1717-1726 ◽  
Author(s):  
JULIANA WOJCIECHOWSKI ◽  
ANDRÉ A. PADIAL
Keyword(s):  
Temporal Variability ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Environmental Variability ◽  
Time Lag ◽  
Cyanobacteria Blooms ◽  
Environment Variables ◽  
Sampling Points ◽  
The Relationship

One of the main goals of monitoring cyanobacteria blooms in aquatic environments is to reveal the relationship between cyanobacterial abundance and environmental variables. Studies typically correlate data that were simultaneously sampled. However, samplings occur sparsely over time and may not reveal the short-term responses of cyanobacterial abundance to environmental changes. In this study, we tested the hypothesis that stronger cyanobacteria x environment relationships in monitoring are found when the temporal variability of sampling points is incorporated in the statistical analyses. To this end, we investigated relationships between cyanobacteria and seven environmental variables that were sampled twice yearly for three years across 11 reservoirs, and data from an intensive monitoring in one of these reservoirs. Poor correlations were obtained when correlating data simultaneously sampled. In fact, the 'highly recurrent' role of phosphorus in cyanobacteria blooms is not properly observed in all sampling periods. On the other hand, the strongest correlation values for the total phosphorus x cyanobacteria relationship were observed when we used the variation of sampling points. We have also shown that environment variables better explain cyanobacteria when a time lag is considered. We conclude that, in cyanobacteria monitoring, the best approach to reveal determinants of cyanobacteria blooms is to consider environmental variability.

scholarly journals Community Structure of Benthic Algae in a Lotic Ecosystem, Karbala Province-Iraq

2017 ◽  
Vol 14 (4) ◽  
pp. 692-706 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Community Structure ◽  
Chlorophyll A ◽  
Total Nitrogen ◽  
Environmental Variables ◽  
Nitrogen Limitation ◽  
Benthic Algae ◽  
Concrete Lining ◽  
Qualitative And Quantitative ◽  
Quantitative Studies ◽  
Lotic Ecosystem

This study focused on benthic algae (epipelic and attached algae on concrete lining stream) in Bani-Hassan stream in Holly Karbala, Iraq. The qualitative and quantitative studies of benthic algae were done by collecting 240 samples from five sites in the study area for the period from December 2012 to November 2013. Also, the environmental variables of the stream were examined in term of temporary and spatial. The results showed that the stream was alkaline, hard, oligohaline and a well aerated. The total nitrogen to the total phosphorus (TN: TP) ratio indicates nitrogen limitation. 129 species of benthic algae belonging to 57 genera were identified. Bacillariophyceae (diatoms) was the predominant taxon (95 species) followed by Chlorophyceae (16 species), Cyanophyceae (14 species), Euglenophyceae (3 species) and Pyrophyceae (one species). Some genera were found throughout the study period: Nitzschia, Navicula, Cymbella, Gomphonema, Surirella, Cocconeis, Aulacoseira, Oscillatoria, Lyngbya, Spirulina, and ? Scenedesmus. Site 3 recorded the highest total number of algae in spring 2013, and the lowest total number was at site 5 in Autumn 2013. The chlorophyll-a concentration did not match the total number of algae.

scholarly journals Rare microbes from diverse Earth biomes dominate community activity

2019 ◽  
Author(s):  
Rohan Sachdeva ◽  
Barbara J. Campbell ◽  
John F. Heidelberg
Keyword(s):  
Community Structure ◽  
Microbial Activity ◽  
Ecosystem Function ◽  
Total Activity ◽  
Reaction Rates ◽  
Community Activity ◽  
Crucial Component ◽  
Tightly Coupled ◽  
The Relationship

AbstractMicrobes are the Earth’s most numerous organisms and are instrumental in driving major global biological and chemical processes. Microbial activity is a crucial component of all ecosystems, as microbes have the potential to control any major biochemical process. In recent years, considerable strides have been made in describing the community structure,i.e. diversity and abundance, of microbes from the Earth’s major biomes. In virtually all environments studied, a few highly abundant taxa dominate the structure of microbial communities. Still, microbial diversity is high and is concentrated in the less abundant, or rare, fractions of the community,i.e. the “long tail” of the abundance distribution. The relationship between microbial community structure and activity, specifically the role of rare microbes, and its connection to ecosystem function, is not fully understood. We analyzed 12.3 million metagenomic and metatranscriptomic sequence assemblies and their genes from environmental, human, and engineered microbiomes, and show that microbial activity is dominated by rare microbes (96% of total activity) across all measured biomes. Further, rare microbial activity was comprised of traits that are fundamental to ecosystem and organismal health,e.g. biogeochemical cycling and infectious disease. The activity of rare microbes was also tightly coupled to temperature, revealing a link between basic biological processes,e.g. reaction rates, and community activity. Our study provides a broadly applicable and predictable paradigm that implicates rare microbes as the main microbial drivers of ecosystem function and organismal health.

scholarly journals Rediscovery of the endemic gastropod Dianella schlickumi (Gastropoda, Hydrobiidae) and its discrimination from Dianella thiesseana: environmental correlates and implications for their conservation

2018 ◽  
Vol 27 ◽  
pp. 35-58
Author(s):  
Chrysoula Ntislidou ◽  
Canella Radea ◽  
Sinos Giokas ◽  
Martin T. Pusch ◽  
Maria Lazaridou ◽  
...  
Keyword(s):  
Community Structure ◽  
Environmental Variables ◽  
Redundancy Analysis ◽  
Habitat Degradation ◽  
Effective Management ◽  
Environmental Correlates ◽  
Narrow Endemic ◽  
Morphometric Analyses ◽  
Management Plans ◽  
Anatomical Characters

The aquatic snail genus Dianella (Gastropoda: Hydrobiidae) has only two representatives in Greece: Dianellaschlickumi Schütt, 1962 and Dianellathiesseana (Kobelt, 1878). D.schlickumi, a narrow endemic species to Lake Amvrakia (in Aitoloakarnania, western-central Greece), is considered as Critically Endangered (Possibly Extinct, sensu IUCN 2017). Our study confirmed its presence in Lake Amvrakia, where it had not been detected for more than 30 years. We document the unknown anatomical characters based on the D.schlickumi specimens. Moreover, the presence of D.thiesseana in the nearby lakes Trichonis and Lysimachia was also confirmed, while morphometric analyses enabled the discrimination between the two species. Redundancy Analysis revealed conductivity, dissolved oxygen and pH as the main environmental variables related to the above species’ distribution, shaping their community structure. Both Dianella species require urgent conservation measures to be enforced, due to their habitat degradation from human activities, which are limiting and fragmenting their range. For that purpose, effective management plans have to be elaborated and implemented at the mentioned lakes, focusing on the reduction of human pressures and on the improvement of their habitats.

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