Journal articles on the topic 'Abiotic and biotic variables'
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McNab, W. Henry, and Tara L. Keyser. "A vegetative index of stand productivity based on tree inventory for predicting oak site index in the Central Hardwood Region." Canadian Journal of Forest Research 50, no. 8 (August 2020): 760–73. http://dx.doi.org/10.1139/cjfr-2019-0412.
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Models for prediction of site index (SI) typically include only abiotic causal variables (e.g., soil) and lack biotic response variables (e.g., vegetation), which could exhibit greater sensitivity to important environmental factors affecting tree height growth. Our study objective was to evaluate Whittaker’s moisture condition index (MCI) (R.H. Whittaker. 1956. Ecol. Monogr. 26: 1–80) as a potential biotic variable for inclusion with conventional abiotic variables in oak (Quercus L.) SI prediction models. The MCI is the sum of relative abundances of inventoried plot tree species weighted by their moisture affinity classification. We compared regression parameters of conventional base models including only abiotic variables with exploratory models configured with abiotic variables and MCI for explaining variation of SI. The best abiotic model included only aspect. When MCI was included in the abiotic model, aspect became insignificant, resulting in a single-variable biotic model that accounted for increased SI variation. The MCI biotic model remained significant when tested with independent data from a distant location. The MCI is easily calculated using plot inventory data, and with further evaluation, it may be confirmed as a useful biotic variable in combination with abiotic soil and topographic variables for prediction of oak SI.
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Aryanti, Nirmala Ayu, Febri Arif Cahyo Wibowo, Mahidi Mahidi, Frita Kusuma Wardhani, and I. Komang Tri Wijaya Kusuma. "Hubungan Faktor Biotik dan Abiotik Terhadap Keanekaragaman Makrobentos di Hutan Mangrove Kabupaten Lombok Barat." Jurnal Kelautan Tropis 24, no. 2 (May 19, 2021): 185–94. http://dx.doi.org/10.14710/jkt.v24i2.10044.
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High human activity around the coastal area will affect the mangrove ecosystem and the biota such as macrobenthos. Benthic diversity can reflect conditions of mangrove ecosystem, that slow growth and sensitive to environmental changes. This study aims to determine the influence of biotic and abiotic environments on the macrobenthos in Cendi Manik Village, Sekotong District, West Lombok Regency, West Nusa Tenggara. Data collection of macrobenthos, biotic and abiotic environments in natural and rehabilitation mangrove, then the diversity species of macrobenthos with biotic and abiotic environmental variables were analyzed multiple regression. The most dominant vegetations are Rhizophora mucronata Lam and Avicennia marina Forssk. The diversity index for macrobenthos is low (H’ 1,207) in natural and rehabilitation mangrove. Macrobenthos between two location have high similarity with 84,6%. The result of multiple regression test showed that most influencing of macrobenthos were mud thickness and brightness. Aktivitas manusia yang tinggi sekitar kawasan pesisir akan mempengaruhi ekosistem mangrove dan biota di dalamnya seperti makrobentos. Keanekaragaman bentos dapat mampu mencerminkan kondisi ekosistem mangrove, pertumbuhan yang lambat dan sensitif terhadap perubahan lingkungan. Penelitian ini bertujuan untuk mengetahui hubungan lingkungan biotik dan abiotik terhadap makrobentos yang ada di Desa Cendi Manik Kecamatan Sekotong Kabupaten Lombok Barat Nusa Tenggara Barat. Pengumpulan data makrobentos, biotik dan abiotik lingkungan pada hutan mangrove alam dan rehabilitasi, kemudian keanekaragaman jenis makrobentos dengan variabel lingkungan biotik dan abiotik dianalisis regresi berganda. Jenis vegetasi yang paling mendominasi adalah jenis Rhizophora mucronata Lam dan Avicennia marina Forssk. Keanekaragaman jenis makrobentos termasuk dalam kategori rendah (H’ 1,207) di hutan mangrove alam dan rehabilitasi. Jenis makrobentos antara dua lokasi tersebut memiliki kemiripan yang tinggi yaitu 84,6 %. Uji regresi berganda diperoleh variabel lingkungan yang paling berpengaruh pada keanekaragaman jenis makrobentos adalah ketebalan lumpur dan kedalaman kecerahan air.
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De Araújo Lira, André Felipe, Stênio Ítalo Araújo Foerster, Adriano Medeiros DeSouza, and Luis F. De Armas. "Disentangling diversity patterns in Cuban scorpions (Arachnida: Scorpiones)." Novitates Caribaea, no. 19 (January 17, 2022): 72–91. http://dx.doi.org/10.33800/nc.vi19.290.
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The assembly of communities is often viewed as a process involving the dispersal of species from a regional pool. An oceanic island provides a unique opportunity to test such a hypothesis and many others related to the patterns and processes behind biodiversity. Our aim was to investigate the patterns of scorpion diversity in the Cuban archipelago, using biotic and abiotic variables and their interactions as explanatory features. We use biotic and abiotic variables related to vegetation, climate and topography characterize the landscape of the Cuban archipelago. In this way, we analyze the patterns of beta diversity of the scorpions, verifying the effects of the variables alone and together. Scorpion fauna of the Cuban archipelago comprises 61 species, grouped into nine genera and two families: Buthidae and Diplocentridae. The interplay between biotic and abiotic variables explained scorpion species composition, especially when spatial predictors were considered. Climatic and spatial predictors affected scorpion beta diversity in terms of richness difference. These patterns are discussed emphasizing the role of biotic and abiotic environmental features and their interactions on the mechanisms of scorpion biodiversity generation and maintenance in Cuban archipelago.
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Bennington, S., W. Rayment, and S. Dawson. "Putting prey into the picture: improvements to species distribution models for bottlenose dolphins in Doubtful Sound, New Zealand." Marine Ecology Progress Series 653 (October 29, 2020): 191–204. http://dx.doi.org/10.3354/meps13492.
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Species distribution models (SDMs) often rely on abiotic variables as proxies for biotic relationships. This means that important biotic relationships may be missed, creating ambiguity in our understanding of the drivers of habitat use. These problems are especially relevant for populations of predators, as their habitat use is likely to be strongly influenced by the distribution of their prey. We investigated habitat use of a population of a top predator, bottlenose dolphins Tursiops truncatus, in Doubtful Sound, New Zealand, using generalised additive models, and compared the results of models with and without biotic predictor variables. We found that although habitat use by bottlenose dolphins was significantly correlated with abiotic variables that likely describe foraging areas, introduction of biotic variables describing potential prey almost doubled the deviance explained, from 19.8 to 39.1%. Biotic variables were the most important of the predictors used, and indicated that the dolphins showed a preference for areas with a high abundance of a reef fish, girdled wrasse Notolabrus cinctus. For the dolphins of Doubtful Sound, these results show the importance of prey distribution in driving habitat use. On a broader scale, our results indicate that making an effort to include true biotic descriptors in SDMs can improve model performance, resulting in better understanding of the drivers of distribution of marine predators.
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Ghini, Raquel, and Marcelo Augusto Boechat Morandi. "Biotic and abiotic factors associated with soil suppressiveness to Rhizoctonia solani." Scientia Agricola 63, no. 2 (April 2006): 153–60. http://dx.doi.org/10.1590/s0103-90162006000200007.
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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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Piana, Pitágoras Augusto, Luiz Carlos Gomes, and Elimaida Mayo Cortez. "Factors influencing Serrapinnus notomelas (Characiformes: Characidae) populations in upper Paraná river floodplain lagoons." Neotropical Ichthyology 4, no. 1 (March 2006): 81–86. http://dx.doi.org/10.1590/s1679-62252006000100008.
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Identification of variables that influence fish populations is one of the main challenges in ecology. To explore this, data were collected quarterly from February 2000 to November 2001 using seines, along the shore of four isolated lagoons of the upper Paraná River floodplain. Serrapinnus notomelas was selected to assess the effect of abiotic and biotic variables using indirect gradient analysis. Abiotic variables were summarized by principal components analysis (PCA) and then the scores of the axis retained for interpretation were correlated with abundances of S. notomelas. Variables that best explained S. notomelas abundance were surface area of the lagoon, total suspended solids and Secchi depth (these last two, indirectly linked to predation). The most relevant biotic variable that determined population size of S. notomelas was predation.
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ANDERSON, T. K., and M. V. K. SUKHDEO. "Abiotic versus biotic hierarchies in the assembly of parasite populations." Parasitology 137, no. 4 (December 22, 2009): 743–54. http://dx.doi.org/10.1017/s0031182009991430.
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SUMMARYThe presence or absence of parasites within host populations is the result of a complex of factors, both biotic and abiotic. This study uses a non-parametric classification tree approach to evaluate the relative importance of key abiotic and biotic drivers controlling the presence/absence of parasites with complex life cycles in a sentinel, the common killifish Fundulus heteroclitus. Parasite communities were classified from 480 individuals representing 15 fish from 4 distinct marsh sites in each of 4 consecutive seasons between 2006 and 2007. Abiotic parameters were recorded at continuous water monitoring stations located at each of the 4 sites. Classification trees identified the presence of benthic invertebrate species (Gammarus sp. and Littorina sp.) as the most important variables in determining parasite presence: secondary splitters were dominated by abiotic variables including conductance, pH and temperature. Seventy percent of hosts were successfully classified into the correct category (infected/uninfected) based on only these criteria. The presence of competent definitive hosts was not considered to be an important explanatory variable. These data suggest that the most important determinant of the presence of these parasite populations in the common killifish is the availability of diverse communities of benthic invertebrates.
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Simões, Marianna V. P., and A. Townsend Peterson. "Importance of biotic predictors in estimation of potential invasive areas: the example of the tortoise beetleEurypedus nigrosignatus, in Hispaniola." PeerJ 6 (December 5, 2018): e6052. http://dx.doi.org/10.7717/peerj.6052.
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Climatic variables have been the main predictors employed in ecological niche modeling and species distribution modeling, although biotic interactions are known to affect species’ spatial distributions via mechanisms such as predation, competition, and mutualism. Biotic interactions can affect species’ responses to abiotic environmental changes differently along environmental gradients, and abiotic environmental changes can likewise influence the nature of biotic interactions. Understanding whether and how to integrate variables at different scales in ecological niche models is essential to better estimate spatial distributions of species on macroecological scales and their responses to change. We report the leaf beetleEurypedus nigrosignatusas an alien species in the Dominican Republic and investigate whether biotic factors played a meaningful role in the distributional expansion of the species into the Caribbean. We evaluate ecological niche models built with an additive gradient of unlinked biotic predictors—host plants, using likelihood-based model evaluation criteria (Akaike information criterion and Bayesian information criterion) within a range of regularization multiplier parameter values. Our results support the argument that ecological niche models should be more inclusive, as selected biotic predictors can improve the performance of models, despite the increased model complexity, and show that biotic interactions matter at macroecological scales. Moreover, we provide an alternative approach to select optimal combination of relevant variables, to improve estimation of potential invasive areas using global minimum model likelihood scores.
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Meier, Eliane S., Felix Kienast, Peter B. Pearman, Jens-Christian Svenning, Wilfried Thuiller, Miguel B. Araújo, Antoine Guisan, and Niklaus E. Zimmermann. "Biotic and abiotic variables show little redundancy in explaining tree species distributions." Ecography 33, no. 6 (November 12, 2010): 1038–48. http://dx.doi.org/10.1111/j.1600-0587.2010.06229.x.
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Borzée, Amaël, Ye Inn Kim, Zoljargal Purevdorj, Irina Maslova, Natalya Schepina, and Yikweon Jang. "Relationship between anuran larvae occurrence and aquatic environment in septentrional east Palearctic landscapes." Herpetozoa 34 (December 14, 2021): 265–70. http://dx.doi.org/10.3897/herpetozoa.34.e68577.
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The presence of amphibian larvae is restricted by both biotic and abiotic variables of the environment. Some of these variables are still undetermined in the septentrional eastern Palearctic where Rana amurensis, Strauchbufo raddei and Dryophytes japonicus are found in large numbers. In this study, we sampled 92 sites across Mongolia, Russia and the Democratic People’s Republic of Korea and measured biotic and abiotic water variables, as well as the height of flooded terrestrial and emergent aquatic vegetation at the breeding site. We determined that the presence of anuran larvae is generally, but not always, linked to pH and temperature. Rana amurensis was not significantly affected by any of the variables measured, while S. raddei was impacted by water conductivity and D. japonicus by pH, temperature and vegetation. Our results highlight a potential risk for these species due to the changes in aquatic variables in response to desertification.
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Sgarzi, Serena, Anna Badosa, Àngels Leiva-Presa, Lluís Benejam, Rocío López-Flores, and Sandra Brucet. "Plankton Taxonomic and Size Diversity of Mediterranean Brackish Ponds in Spring: Influence of Abiotic and Biotic Factors." Water 11, no. 1 (January 9, 2019): 106. http://dx.doi.org/10.3390/w11010106.
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In this study, performed in Mediterranean brackish ponds during spring season, we assessed the effects of biotic interactions and abiotic factors on the size and taxonomic structure of the phytoplankton and zooplankton. We used a taxonomic and a size diversity index as a descriptor of the community structure. We predicted that the size diversity of each trophic level would be mainly related to biotic interactions, such as size-based fish predation (in the case of zooplankton) and food resource availability (in the case of phytoplankton), whereas taxonomic diversity would be more affected by abiotic variables (e.g., conductivity, pond morphology). Our results showed a negative relationship between phytoplankton size diversity and food resource availability leading to low size diversities under food scarcity due to dominance of small species. Conductivity also negatively affected the phytoplankton size diversity, although slightly. Regarding zooplankton size diversity, none of predictors tested seemed to influence this index. Similar fish size diversities among ponds may prevent a significant effect of fish predation on size diversity of zooplankton. As expected, taxonomic diversity of phytoplankton and zooplankton was related to abiotic variables (specifically pond morphometry) rather than biotic interactions, which are usually body size dependent, especially in these species-poor brackish environments.
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Michailidou, Danai-Eleni, Maria Lazarina, and Stefanos P. Sgardelis. "Temperature and Prey Species Richness Drive the Broad-Scale Distribution of a Generalist Predator." Diversity 13, no. 4 (April 15, 2021): 169. http://dx.doi.org/10.3390/d13040169.
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The ongoing climate change and the unprecedented rate of biodiversity loss render the need to accurately project future species distributional patterns more critical than ever. Mounting evidence suggests that not only abiotic factors, but also biotic interactions drive broad-scale distributional patterns. Here, we explored the effect of predator-prey interaction on the predator distribution, using as target species the widespread and generalist grass snake (Natrix natrix). We used ensemble Species Distribution Modeling (SDM) to build a model only with abiotic variables (abiotic model) and a biotic one including prey species richness. Then we projected the future grass snake distribution using a modest emission scenario assuming an unhindered and no dispersal scenario. The two models performed equally well, with temperature and prey species richness emerging as the top drivers of species distribution in the abiotic and biotic models, respectively. In the future, a severe range contraction is anticipated in the case of no dispersal, a likely possibility as reptiles are poor dispersers. If the species can disperse freely, an improbable scenario due to habitat loss and fragmentation, it will lose part of its contemporary distribution, but it will expand northwards.
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Kollars, Thomas M. "Factors Affecting the Distribution of Bot Flies (Diptera: Oestridae) on Islands in Lake Barkley Kentucky and Tennessee." Journal of Entomological Science 30, no. 4 (October 1, 1995): 513–18. http://dx.doi.org/10.18474/0749-8004-30.4.513.
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The present study analyzes the effect of six abiotic and eight biotic variables on the presence of Cuterebra on islands in Lake Barkley in Kentucky and Tennessee. Abiotic factors were: area, length, distance to mainland, distance to nearest island, elevation, and last inundation. Biotic factors were: tree species diversity (sd), shrub sd, vine sd, and herbaceous sd, percent herbaceous cover, percent tree cover, mammal species, and small mammal sd. A Cuterebra, presumably C. fontinella fontinella (Clark), infested white-footed mice on two islands and house mice on one island. Six other small mammal species were not infested. There was no significant difference between prevalence and sex of host. No correlation between the presence of Cuterebra and biotic or abiotic factors was found (P > 0.05). The presence of house mice did not determine the presence of Cuterebra on islands. Factors associated with island biogeography did not appear to play a role in determining the presence of Cuterebra. Only the presence of white-footed mice was related functionally to the presence of Cuterebra on islands (R2 = 0.85; P < 0.05). Although other small mammals may be found on islands, the occurrence and prevalence of C. fontinella on islands was primarily limited by the presence of white-footed mice regardless of other abiotic or biotic factors.
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Boyero, Luz, Richard G. Pearson, Cang Hui, Mark O. Gessner, Javier Pérez, Markos A. Alexandrou, Manuel A. S. Graça, et al. "Biotic and abiotic variables influencing plant litter breakdown in streams: a global study." Proceedings of the Royal Society B: Biological Sciences 283, no. 1829 (April 27, 2016): 20152664. http://dx.doi.org/10.1098/rspb.2015.2664.
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Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder ( Alnus glutinosa ) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons.
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Cunnington, Glenn M., James Schaefer, Joseph E. Cebek, and Dennis Murray. "Correlations of biotic and abiotic variables with ground surface temperature: An ectothermic perspective." Écoscience 15, no. 4 (December 2008): 472–77. http://dx.doi.org/10.2980/15-4-3140.
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Hattum, B. van. "Trace Metals in Populations of Freshwater Isopods: Influence of Biotic and Abiotic Variables." Archives of Environmental Contamination and Toxicology 31, no. 3 (September 1, 1996): 303–18. http://dx.doi.org/10.1007/s002449900114.
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van Hattum, B., N. M. van Straalen, and H. A. J. Govers. "Trace metals in populations of freshwater isopods: Influence of biotic and abiotic variables." Archives of Environmental Contamination and Toxicology 31, no. 3 (October 1996): 303–18. http://dx.doi.org/10.1007/bf00212669.
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Lundqvist, Henrik, Lennart Norell, and Öje Danell. "Relationships between biotic and abiotic range characteristics and productivity of reindeer husbandry in Sweden." Rangifer 29, no. 1 (December 1, 2009): 1–24. http://dx.doi.org/10.7557/2.29.1.198.
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Reindeer husbandry is a form of pastoralism where vast areas are used as forage ranges throughout the year. The productivity of the reindeer industry in Sweden is affected by a multitude of factors on different geographical and temporal scales. Our aim was to find combinations of factors characterizing the environmental conditions for reindeer husbandry in the 51 herding districts in Sweden, which correlate strongly with variations in productivity both between herding districts in general and between years within districts. Productivities were described by estimated herd growth rates and carcass condition of slaughtered females and calves. These dependent variables were related to the environmental independent variables using linear regression models and structural equation modelling. The independent variables were either considered as stable (e.g. topography, vegetation and infrastructure) or temporally changing (e.g. season lengths, weather events, disturbances and animal slaughter strategies). The most relevant independent variables were included in a cluster analysis to suggest a grouping of herding districts based on similarities in environmental conditions. Considerably larger variation in productivity was found between herding districts than between years. Different variables were found to be important for between-district and within-district variations, respectively. Season lengths and animal densities were found significant at both levels of variation. Other variables found to be relevant were ruggedness, snow condition, harassing insect activity, supplementary feeding, calf slaughter ratio and previousyear animal condition. Snow precipitation, ice-crust formation and forage quality were presumed to be relevant for reindeer productivity, but were not found to have a large impact on productivity. These factors, however, may have been counteracted by husbandry measures, statistically incorporated in animal density variables, or by being strongly correlated with other, more significant variables. Several of the variables that were found to be important for productivity are correlated with climate and weather and therefore foreseen to be altered in a climatic change perspective.
Abstract in Swedish / Sammanfattning:
Kopplingar mellan biotiska och geografiska karaktäristika av renskötselområden och renproduktivitet i Sverige
Renskötseln i Sverige är en form av pastoralism som använder stora ytor till betesmark. Produktiviteten inom rennäringen i Sverige beror på ett stort antal faktorer som varierar geografiskt och över tid. Undersökningens mål var att hitta kombinationer av faktorer som karaktäriserar förutsättningarna för renskötsel inom de 51 samebyarna i Sverige. Detta genomfördes genom att koppla variationen i renproduktivitet med kombinationer av omgivningsvariabler på sameby- och årsbasis. Produktiviteten definierades genom beräknad hjordtillväxt, slaktkroppskvalitet och vikter på slaktkroppar. Produktivitetsvariablerna relaterades till omgivningsvariablerna genom multipel linjär regression och strukturerad ekvationsmodellering (SEM). Omgivningsvariablerna ansågs för denna undersöknings tidsperspektiv vara antingen stabila (t.ex. topografi, vegetation och infrastrukturer) eller varierande över tid (t.ex. säsongslängder, väderhändelser, störningar och slaktstrategier). De mest relevanta omgivningsvariablerna användes i en klusteranalys för att gruppera samebyarna enligt deras likheter i förutsättningar för renskötsel. Variationen i produktivitet var större mellan samebyar än mellan år inom samebyar. Olika omgivningsvariabler visade sig vara relevanta mellan samebyar och mellan år. Säsongslängd och djurtäthet var relevanta i båda skalorna (mellan samebyar och mellan år), medan faktorer såsom topografisk brutenhet, snöförhållanden, aktivitet av störande insekter, stödutfodring, kalvslaktsandel och kondition på föregående års slaktkroppar var relevanta i en av dem. Snöfall, skarebildning och beteskvalitet antogs vara relevanta men visade sig inte vara signifikant korrelerade med produktiviteten. Dessa faktorer kan dock ha motverkats genom renskötselåtgärder, blivit statistisk inkorporerade i rentäthetsvariabler eller varit korrelerade med andra mer relevanta variabler. Flera av de signifikanta omgivningsvariablerna är väder- och klimatrelaterade, vilka därför antas förändras i den pågående klimatförändringen.
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von Müller, A. R., D. Renison, and A. M. Cingolani. "Cattle landscape selectivity is influenced by ecological and management factors in a heterogeneous mountain rangeland." Rangeland Journal 39, no. 1 (2017): 1. http://dx.doi.org/10.1071/rj15114.
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Few studies addressing drivers of cattle selectivity focus on the combination of ecological (biotic and abiotic) and management factors such as rotational systems, paddock sizes and paddock shapes. As a consequence, it is difficult to prioritise management practices integrating information of different driving factors. In a heterogeneous mountain rangeland in Central Argentina we established a total of 419 square study plots of 1 ha located in 18 paddocks with differing sizes, shapes and cattle grazing management. Plots were small samples of landscapes, covering all existing variability in vegetation and physiography. For each plot we estimated the annual cattle use, average seasonal cattle density, forage types and abiotic characteristics. We used general linear models to show that selectivity was mainly driven by biotic variables. Cattle selected landscapes dominated by short palatable plants, but the strength of this influence differed among paddocks. Selectivity was strongest in paddocks with low abundance of lawns dominated by short palatable plants and low annual stocking rate. As stocking rate and the availability of lawns increased, selectivity strength decreased. Abiotic variables had far less influence than biotic variables, showing that cattle tended to avoid rough landscapes with steep terrain in the wet-warm season; and to be attracted by permanent water sources during the dry-cold season. Seasonal stocking density and paddock size had no detectable influence on cattle selectivity and distribution. Paddock shape influenced distribution but not the strength of forage selectivity. We conclude that in our system, cattle selectivity is mainly driven by biotic factors, and the most effective methods of changing the consequent distribution pattern is by manipulating forage types and paddock shape. The role of stocking rate remains controversial as it was correlated with the proportion of lawns in the paddock.
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Cardinale, M., and F. Arrhenius. "The influence of stock structure and environmental conditions on the recruitment process of Baltic cod estimated using a generalized additive model." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 12 (December 1, 2000): 2402–9. http://dx.doi.org/10.1139/f00-221.
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The recruitment process and its underlying mechanisms are among the most studied phenomena in fisheries ecology. Traditional models estimate fish recruitment assuming a direct relationship with spawning stock size. However, highly variable environmental conditions, feeding conditions, and other factors can influence and complicate the results of a simple linear regression analysis between stock and recruitment. We used generalized additive models (GAMs) to investigate the influence of environmental conditions and stock structure on the recruitment processes of Baltic cod. The interaction between abiotic factors and old spawners (>5+ years) and eggs produced by old spawners were the most significant explanatory variables. Eggs produced by young spawners have a positive impact on cod recruitment only at high levels of reproductive volume, while old spawners' eggs have the highest positive effect at low levels of reproductive volume. Here we show: (i) that the number of Baltic cod recruits is strictly dependent on the age structure of the population; (ii) that interactions between biotic and abiotic factors are crucial in explaining recruitment variability; and (iii) that GAMs are a powerful technique for defining and quantifying the intricate multidimensional relationship between biotic and abiotic variables involved in recruitment processes.
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Büyüksönmez, Fatïh, Thomas F. Hess, Ronald L. Crawford, and Richard J. Watts. "Toxic Effects of Modified Fenton Reactions on Xanthobacter flavus FB71." Applied and Environmental Microbiology 64, no. 10 (October 1, 1998): 3759–64. http://dx.doi.org/10.1128/aem.64.10.3759-3764.1998.
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ABSTRACT The toxic effects of modified Fenton reactions onXanthobacter flavus FB71, measured as microbial survival rates, were determined as part of an investigation of simultaneous abiotic and biotic oxidations of xenobiotic chemicals. A central composite, rotatable experimental design was developed to study the survival rates of X. flavus under various concentrations of hydrogen peroxide and iron(II) and at different initial cell populations. A model based on the experimental results, relating microorganism survival to the variables of peroxide, iron, and cellular concentrations was formulated and fit the data reasonably well, with a coefficient of determination of 0.76. The results of this study indicate that the use of simultaneous abiotic and biotic processes for the treatment of xenobiotic compounds may be possible.
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Takahashi, Érica M., Fábio A. Lansac-Tôha, Juliana D. Dias, and Claudia C. Bonecker. "Daily variation of zooplankton abundance and evenness in the Rosana reservoir, Brazil: biotic and abiotic inferences." Iheringia. Série Zoologia 104, no. 1 (March 2014): 21–31. http://dx.doi.org/10.1590/1678-4766201410412131.
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The zooplankton community presents stochastic temporal fluctuation and heterogeneous spatial variation determined by the relationships among the organisms and environmental conditions. We predicted that the temporal and spatial zooplankton distribution is heterogeneous and discrete, respectively, and that the daily variation of most abundant species is related to environmental conditions, specifically the availability of resources. Zooplankton samples were collected daily at three sampling stations in a lateral arm of the Rosana Reservoir (SP/PR). The zooplankton did not present significant differences in abundance and evenness among sampling stations, but the temporal variation of these attributes was significant. Abiotic variables and algal resource availability have significantly explained the daily variation of the most abundant species (p<0.001), however, the species distribution makes inferences on biotic relationships between them. Thus, not only the food resource availability is influential on the abundance of principal zooplankton species, but rather a set of factors (abiotic variables and biotic relationships).
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Sipaúba-Tavares, L. H., P. A. Durigan, F. A. Berchielli-Morais, and R. N. Millan. "Influence of inlet water on the biotic and abiotic variables in a fish pond." Brazilian Journal of Biology 77, no. 2 (August 15, 2016): 277–83. http://dx.doi.org/10.1590/1519-6984.12315.
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Abstract The effects of treated and untreated water inlets with macrophytes on the improvement of water quality and zooplankton community were evaluated in a fish pond with continuous water flow. Water and zooplankton samples were retrieved at four sites during nine months. There were differences (p<0.01) between inlet water from fish pond and inlet water from canal with macrophytes, featuring higher concentrations of nutrient load, mainly TAN and TP in the former. The inlet water from fish pond contained a higher number of abundant species (9 species), whilst the water supply from the canal with macrophytes had a greater richness (31 species) of zooplankton species. Results showed that inlet water without macrophytes directly affected the characteristics of the water column and the dominance of zooplankton species such as Thermocyclops decipiens, and greater abundance of Rotifera species. Since aquatic plants in the inlet water of fish pond analyzed showed lower allochthonous material loads from the previous fish pond, the management adopted with macrophytes may be applied to avoid eutrophication risks, common in farm ponds.
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Abdel-Monem, Ahmed, and Adel Kanswa. "SOME BIOTIC AND ABIOTIC VARIABLES CONTROLLING PRIMARY PRODUCTIVITY IN HYPERTROPHIC LAKE (LAKE QARUN-EGYPT)." Egyptian Journal of Aquatic Biology and Fisheries 5, no. 3 (July 1, 2001): 1–16. http://dx.doi.org/10.21608/ejabf.2001.1686.
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Luiz, Osmar J., Thiago C. Mendes, Diego R. Barneche, Carlos G. W. Ferreira, Ramon Noguchi, Roberto C. Villaça, Carlos A. Rangel, João L. Gasparini, and Carlos E. L. Ferreira. "Community structure of reef fishes on a remote oceanic island (St Peter and St Paul’s Archipelago, equatorial Atlantic): the relative influence of abiotic and biotic variables." Marine and Freshwater Research 66, no. 8 (2015): 739. http://dx.doi.org/10.1071/mf14150.
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This study investigates the reef fish community structure of the world’s smallest remote tropical island, the St Peter and St Paul’s Archipelago, in the equatorial Atlantic. The interplay between isolation, high endemism and low species richness makes the St Peter and St Paul’s Archipelago ecologically simpler than larger and highly connected shelf reef systems, making it an important natural laboratory for ecology and biogeography, particularly with respect to the effects of abiotic and biotic factors, and the functional organisation of such a depauperate community. Boosted regression trees were used to associate density, biomass and diversity of reef fishes with six abiotic and biotic variables, considering the community both as a whole and segregated into seven trophic groups. Depth was the most important explanatory variable across all models, although the direction of its effect varied with the type of response variable. Fish density peaked at intermediate depths, whereas biomass and biodiversity were respectively positively and negatively correlated with depth. Topographic complexity and wave exposure were less important in explaining variance within the fish community than depth. No effects of the predictor biotic variables were detected. Finally, we notice that most functional groups are represented by very few species, highlighting potential vulnerability to disturbances.
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Clarke, Peter J. "Seeking global generality: a critique for mangrove modellers." Marine and Freshwater Research 65, no. 10 (2014): 930. http://dx.doi.org/10.1071/mf13326.
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Large datasets have allowed more generality in ecology than ever before but this may come at a cost of precision and realism. Modelling the dominance of mangrove species on the basis of observational data of few abiotic variables is an example of where this comes at a cost of realism. This is because the multi-factorial and inter-correlated nature of abiotic and biotic variables that limit the distribution of mangroves cannot be accounted for in statistical models on the basis of few observational data. The solution to the seemingly intractable problem of achieving general explanations is to better coordinate comparative and experimental research across a global range of mangrove environments.
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WIRYANTO, WIRYANTO, SUNARTO SUNARTO, and SLAMET MARDIYANTO RAHAYU. "Biodiversity of mangrove aquatic fauna in Purworejo, Central Java, Indonesia." Biodiversitas Journal of Biological Diversity 18, no. 4 (October 4, 2017): 1344–52. http://dx.doi.org/10.13057/biodiv/d180409.
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Wiryanto, Sunarto, Rahayu SM. 2017. Biodiversity of mangrove aquatic fauna in Purworejo, Central Java, Indonesia. Biodiversitas 18: 1344-1352. Mangrove areas have important roles of ecologic, socio-economic, and socio-culture in ecosystem. Mangrove areas in Purworejo go into degradation as an impact of illegal logging, fishpond area expansion, settlements expansion and extension of agriculture area. All of the activities will influence the communities’ structure of mangroves vegetation and aquatic fauna. The purposes of research are to observe (i) biodiversity of mangroves aquatic fauna; (ii) correlation between mangrove vegetation and aquatic fauna; and (iii) the influence of abiotic factors towards biotic condition in research sites. This research was conducted in June-September 2016 at 3 stations and was determined with purposive sampling method. The research stations are Gedangan (Station 1), Jatikontal (Station 2) and Ngentak (Station 3). Vegetation of mangrove and aquatic fauna were observed with method of line transect and sampling removal. Association between variables (vegetation and aquatic fauna) is analyzed with Pearson Correlation Test. Influence of abiotic factors (physics and chemicals) on biotic (vegetation and aquatic fauna) is analyzed with t-test and regression test. According to the research, 34 species of aquatic fauna are from mangroves area of Purworejo. Highest value of aquatic fauna is found in Station 3 (ID 2.50). Pearson correlation test between vegetation and aquatic fauna obtains r value of 0,104. The t-test results a significant difference (sig 0.000) between abiotic factors and biotic condition and shows the impact of changes on both. Further test with regression method also indicates a weak impact on changes on abiotic factors towards biotic condition (r2 0.032).
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France, R. L. "Test of Biotic and Abiotic Environmental Determinants of Amphipod (Hyalella azteca) Preamplexus." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 2 (February 1, 1987): 478–82. http://dx.doi.org/10.1139/f87-058.
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Variation in reproductive behavior (preamplexus) of the amphipod Hyalella azteca among 10 Canadian Shield lakes in Ontario was positively correlated with water temperature, possibly through its influence on either activity patterns or diapausal endocrinology. Intensity of preamplexus was not correlated with other abiotic variables including lake pH, alkalinity, total phosphorus, or chlorophyll a concentration. Similarly, the complicated evolutionary "strategies" suggested by Strong involving alterations in optimal mating tactics in response to differences in intensity offish predation, amphipod density, or habitat heterogeneity did not occur in these lakes.
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Brown, Kathryn, and Andrew Hansen. "A Landscape Approach to Aspen Restoration: Understanding the Role of Biophysical Setting in Aspen Community Dynamics." UW National Parks Service Research Station Annual Reports 25 (January 1, 2001): 135–39. http://dx.doi.org/10.13001/uwnpsrc.2001.3479.
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The aim of this study is to better understand the relationship of biotic and abiotic variables to the distribution, performance, and rates of loss of aspen in the Greater Yellowstone Ecosystem. Aspen commumtles, though critically important for maintaining biodiversity, soil quality, and nutrient cycling, are declining rapidly in the Northern Rockies. Fire suppression, elk browsing, and climatic change are the most widely advanced explanations for this widespread loss of aspen. The role of biophysical factors (e.g. topography, climate, soils, and competing vegetation) in determining aspen performance, however, is poorly understood. Knowledge of these relationships may provide a basis for tailoring aspen restoration efforts to specific landscape settings. To better understand the influence of biophysical variables on aspen dynamics, this study addresses three hypotheses: 1. The aerial distribution of aspen is not random across the landscape and varies as a function of biophysical setting. 2. Within its distribution, growth rates and productivity of aspen stands differ relative to biotic and abiotic variables. 3. Rates of aspen loss in the landscape differ relative to biophysical setting. Here we report progress on the first year of the two-year study.
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Harbicht, Andrew B., Theodore Castro-Santos, Dimitry Gorsky, David M. Hand, Dylan J. Fraser, and William R. Ardren. "Environmental, anthropogenic, and dietary influences on fine-scale movement patterns of Atlantic salmon through challenging waters." Canadian Journal of Fisheries and Aquatic Sciences 75, no. 12 (December 2018): 2198–210. http://dx.doi.org/10.1139/cjfas-2017-0476.
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Partial barriers to migration can affect migratory fish population dynamics and be influenced by many biotic, abiotic, and anthropogenic factors, including nutritional deficiencies. We investigated how such variables (including a thiamine deficiency) impact fine-scale movement of landlocked Atlantic salmon (Salmo salar) by treating returning spawners with thiamine and observing their attempts to climb a human-altered, high velocity stretch of river using fine-scale radio telemetry. Multiple re-entries into a river section, along with water temperature, strongly influenced movement rates. High or increasing discharge encouraged downstream movement; males abandoned migratory attempts at a higher rate than females. Although thiamine-injected salmon exhibited greater migratory duration, this did not produce a measurable improvement in passage performance, possibly due to the difficulty associated with this section of river — among 24 tagged salmon staging 10.9 attempts each and lasting 1.5 days per attempt on average, only three traversed the entire reach. This study provides new insights into how biotic and abiotic variables affect fish movement, while suggesting limits to the potential for human intervention (thiamine injections) to assist passage through partial migratory barriers.
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Orlando-Bonaca, Martina, Domen Trkov, Katja Klun, and Valentina Pitacco. "Diversity of Molluscan Assemblage in Relation to Biotic and Abiotic Variables in Brown Algal Forests." Plants 11, no. 16 (August 16, 2022): 2131. http://dx.doi.org/10.3390/plants11162131.
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Canopy-forming macroalgae, mainly those belonging to the order Fucales, form the so-called brown algal forests, which are among the most productive assemblages in shallow coastal zones. Their vertical, branching canopies increase nearshore primary production, provide nursery areas for juvenile fish, and sustain understory assemblages of smaller algae and both sessile and vagile fauna. The majority of benthic invertebrates inhabiting these forests have larval stages that spend some time floating freely or swimming in the plankton. Therefore, canopy-forming macroalgae play an important role as species collectors related to larval supply and hydrodynamic processes. During the past several decades, brown algal forests have significantly reduced their extension and coverage in the Mediterranean basin, due to multiple interacting natural and anthropogenic pressures, with negative consequences also for the related fauna. The aim of this research was to examine how differences in macrophyte abundance and structure, as well as environmental variables, affect the associated molluscan communities in the shallow northern Adriatic Sea. Sampling sites with well-developed vegetation cover dominated by different canopy-forming species were selected in the shallow infralittoral belt of the northern Adriatic Sea in the spring–summer period of the years 2019 and 2020. Our results confirm the importance of algal forests for molluscan assemblage, with a total of 68 taxa of molluscs found associated with macrophytes. Gastropods showed the highest richness and abundance, followed by bivalves. Mollusc richness and diversity (in terms of biotic indices) were not related with the degree of development of canopy-forming species (in terms of total cover and total volume), nor with the ecological status of benthic macroalgae at different depths. On the contrary, the variability in molluscan taxa abundances was explained by some environmental variables, such as temperature, pH, light, and nitrates concentration.
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Castilla, Anderson Leonardo, Jairo Mora-Delgado, Miguel Rodríguez-Márquez, and Jaime Lopez. "Cattle movement as a function of some biotic and abiotic factors in a tropical pasture." Revista de Ciencias Agrícolas 39, no. 2 (June 16, 2022): 69–88. http://dx.doi.org/10.22267/rcia.223902.184.
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The research question is how do some biotic and abiotic variables, under a silvopastoral system exert influence on the animal movement? These studies have been carried out through different approaches and have included analyses from empirical to statistical. The aim of this study was to relate cattle grazing sites with some biotic and abiotic factors under a silvopastoral system. The fieldwork was carried out in a paddock of the farm La Reforma located in the upper part of the Magdalena River basin (Tolima, Colombia). Through global positioning devices (GPS), movement, grazing route, and resting data that cattle perform in these habitats during daytime hours were obtained. Six cows (460 kg live weight, not pregnant) were monitored during two periods of the year at one-minute time intervals. Data were processed in a geographic information systems (GIS) environment, and mechanisms and algorithms were used to establish an association of moving animals with some biotic (pasture productivity and cover, trees, and floristic composition) and abiotic factors (climatological season, access to drinking and salt troughs). The results suggest an association between animal movement concerning the different attractants for which the drinking and salt troughs in the paddocks were relevant. In conclusion, the analysis of animal behavior at the landscape level is useful for decision-making in the design of livestock landscapes.
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Civantos-Gómez, Icíar, Javier García-Algarra, David García-Callejas, Javier Galeano, Oscar Godoy, and Ignasi Bartomeus. "Fine scale prediction of ecological community composition using a two-step sequential Machine Learning ensemble." PLOS Computational Biology 17, no. 12 (December 6, 2021): e1008906. http://dx.doi.org/10.1371/journal.pcbi.1008906.
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Prediction is one of the last frontiers in ecology. Indeed, predicting fine-scale species composition in natural systems is a complex challenge as multiple abiotic and biotic processes operate simultaneously to determine local species abundances. On the one hand, species intrinsic performance and their tolerance limits to different abiotic pressures modulate species abundances. On the other hand, there is growing recognition that species interactions play an equally important role in limiting or promoting such abundances within ecological communities. Here, we present a joint effort between ecologists and data scientists to use data-driven models to predict species abundances using reasonably easy to obtain data. We propose a sequential data-driven modeling approach that in a first step predicts the potential species abundances based on abiotic variables, and in a second step uses these predictions to model the realized abundances once accounting for species competition. Using a curated data set over five years we predict fine-scale species abundances in a highly diverse annual plant community. Our models show a remarkable spatial predictive accuracy using only easy-to-measure variables in the field, yet such predictive power is lost when temporal dynamics are taken into account. This result suggests that predicting future abundances requires longer time series analysis to capture enough variability. In addition, we show that these data-driven models can also suggest how to improve mechanistic models by adding missing variables that affect species performance such as particular soil conditions (e.g. carbonate availability in our case). Robust models for predicting fine-scale species composition informed by the mechanistic understanding of the underlying abiotic and biotic processes can be a pivotal tool for conservation, especially given the human-induced rapid environmental changes we are experiencing. This objective can be achieved by promoting the knowledge gained with classic modelling approaches in ecology and recently developed data-driven models.
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OLIVEIRA, FÁBIO H. P. C. DE, ANDRÉ L. S. CAPELA E. ARA, CESAR H. P. MOREIRA, OSMAN O. LIRA, MARIA DO ROSÁRIO F. PADILHA, and NEIDE K. S. SHINOHARA. "Seasonal changes of water quality in a tropical shallow and eutrophic reservoir in the metropolitan region of Recife (Pernambuco-Brazil)." Anais da Academia Brasileira de Ciências 86, no. 4 (December 2014): 1863–72. http://dx.doi.org/10.1590/0001-3765201420140128.
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This study investigated the water quality in an urban eutrophic reservoir in Northeastern Brazil, considering the influence of seasonality. Monthly, samples were collected in the sub-surface reservoir. The following abiotic variables were analyzed: temperature, pH, dissolved oxygen, apparent color, turbidity, conductivity, fluoride, total nitrogen, chlorides, total dissolved solids, total hardness, iron, copper, manganese, aluminum, chlorophyll-a and phaeophytin. Total and thermotolerant coliforms were analyzed according to APHA (2012). Cyanobacteria density was quantified through its biomass. The data were analyzed using one- way ANOVA and Pearson correlation test. Higher values mean phytoplankton biomass (26.3mm3.L–1) occurred in the dry season, especially Planktothrix agardhii and Geiterinema amphibium, which occurred in 100% of samples. High trophic state index was detected throughout the year. Seasonality exerted some influence on both biotic and abiotc variables, leading to changes in water quality of the reservoir.
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Bayat, Mahmoud, Harold Burkhart, Manouchehr Namiranian, Seyedeh Kosar Hamidi, Sahar Heidari, and Majid Hassani. "Assessing Biotic and Abiotic Effects on Biodiversity Index Using Machine Learning." Forests 12, no. 4 (April 10, 2021): 461. http://dx.doi.org/10.3390/f12040461.
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Forest ecosystems play multiple important roles in meeting the habitat needs of different organisms and providing a variety of services to humans. Biodiversity is one of the structural features in dynamic and complex forest ecosystems. One of the most challenging issues in assessing forest ecosystems is understanding the relationship between biodiversity and environmental factors. The aim of this study was to investigate the effect of biotic and abiotic factors on tree diversity of Hyrcanian forests in northern Iran. For this purpose, we analyzed tree diversity in 8 forest sites in different locations from east to west of the Caspian Sea. 15,988 trees were measured in 655 circular permanent sample plots (0.1 ha). A combination of machine learning methods was used for modeling and investigating the relationship between tree diversity and biotic and abiotic factors. Machine learning models included generalized additive models (GAMs), support vector machine (SVM), random forest (RF) and K-nearest–neighbor (KNN). To determine the most important factors related to tree diversity we used from variables such as the average diameter at breast height (DBH) in the plot, basal area in largest trees (BAL), basal area (BA), number of trees per hectare, tree species, slope, aspect and elevation. A comparison of RMSEs, relative RMSEs, and the coefficients of determination of the different methods, showed that the random forest (RF) method resulted in the best models among all those tested. Based on the results of the RF method, elevation, BA and BAL were recognized as the most influential factors defining variation of tree diversity.
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MONELLO, R. J., and M. E. GOMPPER. "Biotic and abiotic predictors of tick (Dermacentor variabilis) abundance and engorgement on free-ranging raccoons (Procyon lotor)." Parasitology 134, no. 14 (August 23, 2007): 2053–62. http://dx.doi.org/10.1017/s0031182007003423.
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SUMMARYWe examined the relative importance of abiotic and biotic factors on the ability of adultDermacentor variabilisticks to attach and engorge with blood across 10 populations of free-ranging raccoons (Procyon lotor). We developeda priorimodels that represented explicit hypotheses based on the literature and tested the ability of these models to explain non-replete and replete (fully engorged with blood) tick infestation using generalized linear models and Akaike's Information Criterion. Abiotic models that included month and site of collection clearly provided a better fit for non-replete tick abundance data, while biotic models with host age and sex covariates best fit the replete tick data. Abiotic models of non-replete abundance were superior to biotic models because of large seasonal and site fluctuations in non-replete abundance that masked differences due to host characteristics. Conversely, best-fitting models of replete tick abundance included only age and sex and suggest that once a tick has reached a host, host-parasite interactions are the primary determinant of engorgement by female ticks. Host population structure may have a large influence on potential cohort size of ticks by reducing or increasing the total number and proportion that can become engorged and moult or lay eggs.
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Wang, Yanrong, Zheng Miao, Yuanshuo Hao, Lihu Dong, and Fengri Li. "Effects of Biotic and Abiotic Factors on Biomass Conversion and Expansion Factors of Natural White Birch Forest (Betula platyphylla Suk.) in Northeast China." Forests 14, no. 2 (February 11, 2023): 362. http://dx.doi.org/10.3390/f14020362.
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Biomass conversion and expansion factors (BCEFs) are widely utilized in national and regional biomass estimates and greenhouse gas reporting, as they can be used to directly transform the stocking volume into biomass. In this study, the power function was used as the basic model form with biotic variables, and abiotic variables were considered to improve the fitting results. Then, the random effects parameters were also introduced into the models to describe the variation of BCEFs among different forest management units. Random sampling strategies were applied to calibrate the random effects. The results showed that the stocking volume exhibited a negative proportional relationship in the stem BCEF (BCEFst), the root BCEF (BCEFro) and the total tree BCEF (BCEFto) models, and the quadratic mean diameter exhibited a positive proportional relationship in the branch BCEF (BCEFbr) and the foliage BCEF (BCEFfol) models. In addition, the fitting effect of generalized models with abiotic predictors was superior to that of the basic models. Considering the effects of abiotic variables on the BCEFs of each component, the results showed that BCEFst and BCEFto decreased as the mean annual precipitation increased; BCEFbr increased as the annual temperature increased; BCEFfol gradually decreased as the elevation increased; and BCEFro first increased with increasing mean annual temperature and then declined. In conclusion, abiotic factors explained the variation in BCEFs for the biomass components of the natural white birch forest. Although the fitting effect of generalized models with abiotic predictors was superior to that of the basic models, the mixed-effects model was preferable for modeling the BCEFs of each component. In addition, the prediction precision of the mixed-effects models enhanced gradually with increasing sample size, and the selection of eight plots for calibration and prediction based on the mixed-effects model was the best sampling strategy in this study of a natural white birch forest.
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Chao, Min, Yun-rong Shi, Wei-min Quan, and Xin-qiang Shen. "Distribution of Macrocrustaceans in Relation to Abiotic and Biotic Variables across the Yangtze River Estuary, China." Journal of Coastal Research 314 (July 14, 2015): 946–56. http://dx.doi.org/10.2112/jcoastres-d-13-00207.1.
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Hegeman, Ericka E., Scott W. Miller, and Karen E. Mock. "Modeling freshwater mussel distribution in relation to biotic and abiotic habitat variables at multiple spatial scales." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 10 (October 2014): 1483–97. http://dx.doi.org/10.1139/cjfas-2014-0110.
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The habitat requirements of many native freshwater mussels remain unclear despite their imperiled status and ecological importance. To explore scale-specific habitat associations in the three genera of mussels found in the western United States (Anodonta, Gonidea, and Margaritifera) we used a multiscale random forest modeling approach to assess functional habitat parameters throughout a 55 km segment of the upper Middle Fork John Day River in northeastern Oregon. We characterized mussel occurrence and density with respect to the hierarchical, hydrogeomorphic structure by sampling reaches of varying valley confinement and channel units nested within individual reaches. Each genus exhibited unique longitudinal trends and channel unit-use patterns. In particular, the large-scale longitudinal trends in Margaritifera occurrence were associated with hydrogeomorphic characteristics at the reach and channel unit scale, with Margaritifera densities peaking in narrow valley segments and in riffles and runs. At the scale of the channel unit, all mussel genera responded to variation in physical habitat characteristics, particularly those that indicated more stable parts of the channel. Our results suggest that spatial patterns in freshwater mussels are associated with the hierarchical structuring of the lotic ecosystem and may provide guidance to restoration efforts.
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Souto, Cintia P., and Peter E. Smouse. "Correlated morphological and genetic patterns in Embothrium coccineum (Proteaceae) across climate and geography: can Embothrium survive patagonian climate change?" Australian Journal of Botany 61, no. 7 (2013): 516. http://dx.doi.org/10.1071/bt13214.
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Adaptive radiation and reproductive isolation can determine the biogeographic structure of any species. We examine patterns of biotic variation in Embothrium coccineum, a Proteaceae tree that spans 20° of latitude and is both morphologically and genetically highly variable. We aim to (1) explore the correspondence between these biotic patterns and current geographic and climatic gradients, and (2) determine whether and how those patterns are likely to respond to changing climate. We conducted separate principal component analyses on biotic and abiotic sets of variables for 34 populations of Embothrium coccineum, accounting for a large fraction of the total variation in each. We then used canonical correlation analyses to optimise the match of those gradients onto each other. Smaller, rounder leaves and particular alleles typify the colder and drier parts of the range, whereas larger, lanceolate leaves and other alleles typify warmer and moister areas. Finally, we mapped biotic profiles onto a predicted climatic landscape, on the basis of doubling of CO2 projections. The climatic regime is predicted to shift geographically, but this lineage has successfully responded to repeated and dramatic climatic shifts since the Oligocene, and it should also be able to move and adapt quickly enough to meet the present challenge. More generally, our analytic approach can be extended to analysis of biotic and abiotic patterns in other species facing climatic challenges. Where there is enough biogeographic variation to provide adaptively relevant substrate, and where propagule dispersal is sufficiently extensive to keep up with the pace of spatial climatic shift, such taxa should be able to cope with shifting climate.
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Magnan, Pierre, Marco A. Rodríguez, Pierre Legendre, and Sylvain Lacasse. "Dietary Variation in a Freshwater Fish Species: Relative Contributions of Biotic Interactions, Abiotic Factors, and Spatial Structure." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 12 (December 1, 1994): 2856–65. http://dx.doi.org/10.1139/f94-284.
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We used multivariate analyses to examine which variables among the environmental and spatial components can best account for dietary variation in a freshwater fish, brook trout, Salvelinus fontinalis. The diet composition of brook trout was quantified in 37 lakes of the Laurentian Shield, Québec, Canada. Among the 25 measured environmental variables, fish species composition, sampling date, macrophyte abundance, and trout body length were the best predictors of diet composition. The total variation in diet composition was partitioned into four components: pure environmental 21.6%, pure spatial 23.2%, shared 19.9%, and unexplained 35.3%. A significant spatial trend in diet composition existed even after accounting for the main effects measured by the environmental variables. The two sets of spatial variables, when combined with the environmental descriptors, extracted different components of the dietary variation. The study allowed us to (1) highlight the role of spatial structure in diet variation of brook trout, (2) determine the relative contribution of both environmental and spatial components, and (3) generate testable hypotheses concerning mechanisms underlying the observed structure. Dependent variables other than diet composition, such as the density of different species at different sampling sites, can be used within the same statistical framework in studies of community ecology.
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Stelmakh, Liudmila, and Tatiana Gorbunova. "Emiliania huxleyi blooms in the Black Sea: influence of abiotic and biotic factors." Botanica 24, no. 2 (December 1, 2018): 172–84. http://dx.doi.org/10.2478/botlit-2018-0017.
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Abstract Stelmakh L.V., Gorbunova T.I., 2018: Emiliania huxleyi blooms in the Black Sea: influence of abiotic and biotic factors. - Botanica, 24(2): 172-184. The studies were conducted in the Black Sea in deep and shallow water areas in October 2010 and May 2013. The main abiotic and biotic factors, which control spring and autumn coccolithophorid Emiliania huxleyi blooms, were identified. During late May this phenomenon was observed under optimal light and temperature conditions, and also optimal ratio between mineral forms of nitrogen and phosphorus (N/P) in the water. Biotic variables (the net growth rate of phytoplankton and relative dinoflagellates share in its total biomass) determined the uneven distribution of E. huxleyi within a bloom. In October, water temperature was almost 4ºС lower compared to that in May, and solar radiation intensity decreased approximately by 2-3 times. However, as a result of seasonal adaptation to light and temperature, E. huxleyi abundance reached blooming level. In that period, the variability of N/P ratio in the water and the relative share of diatoms in total biomass of phytoplankton played a major role in the uneven distribution of this coccolithophorid within the studied area. In the areas with low water salinity, a bloom was not developing. Within the main part of the studied water area, the major source of nitrogen was ammonium, which was favourable for the growth of E. huxleyi and dinoflagellates, but limited the growth of diatoms.
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Neff, Margaret R., and Donald A. Jackson. "Regional-scale patterns in community concordance: testing the roles of historical biogeography versus contemporary abiotic controls in determining stream community composition." Canadian Journal of Fisheries and Aquatic Sciences 70, no. 8 (August 2013): 1141–50. http://dx.doi.org/10.1139/cjfas-2012-0497.
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The determinants of a local-scale biological community can include both abiotic and biotic factors acting at a variety of spatial and temporal scales. Previous studies have shown that the Precambrian Shield, a broad-scale geological feature, has distinct abiotic conditions and aquatic communities in lotic systems as compared with systems off-Shield. The relative importance of historical biogeography and postglacial colonization in Ontario versus the role of contemporary abiotic conditions has been debated in determining fish community composition. In this study, we sampled fish and macroinvertebrate community data from south-central Ontario streams to examine the degree of community concordance between fishes and macroinvertebrates and to determine the main abiotic drivers for this biological distinction between Shield and off-Shield areas. This study shows that low-order lotic systems on the Shield differ both abiotically and biotically from adjacent off-Shield systems and that similar abiotic drivers are responsible for structuring both groups of taxa. However, water chemistry and land-use variables are the most important in structuring macroinvertebrate communities, whereas physical habitat plays a larger role for fish communities.
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Paes, J. V. K., E. D. Carvalho, and R. J. da Silva. "Infection levels of Austrodiplostomum compactum (Digenea, Diplostomidae) metacercariae in Plagioscion squamosissimus (Teleostei, Sciaenidae) from the Nova Avanhandava reservoir, São Paulo State, Brazil." Journal of Helminthology 84, no. 3 (November 5, 2009): 284–91. http://dx.doi.org/10.1017/s0022149x09990617.
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AbstractThis study was aimed at evaluating the infection levels of Austrodiplostomum compactum metacercariae in 378 specimens of Plagioscion squamosissimus (‘corvina’ or ‘pescada branca’) from the Nova Avanhandava reservoir, low Tietê River, São Paulo State, Brazil. High prevalence, mean intensity of infection and abundance were observed in P. squamosissimus during most of the study, with the exception of March 2004. The relative condition factor (Kn) did not differ between parasitized and non-parasitized fish. A statistically significant positive correlation was observed between host standard length and intensity of infection. The analysis of biotic and abiotic variables showed that no abiotic variable correlated with parasitic infection levels. Moreover, P. squamosissimus status was demonstrated to be unaffected by A. compactum metacercariae infection.
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Pan, Junxiao, Jinsong Wang, Dashuan Tian, Ruiyang Zhang, Yang Li, Lei Song, Jiaming Yang, Chunxue Wei, and Shuli Niu. "Biotic factors dominantly determine soil inorganic carbon stock across Tibetan alpine grasslands." SOIL 8, no. 2 (October 28, 2022): 687–98. http://dx.doi.org/10.5194/soil-8-687-2022.
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Abstract. The soil inorganic carbon (SIC) pool is a major component of soil carbon (C) pools, and clarifying the predictors of SIC stock is urgent for decreasing soil C losses and maintaining soil health and ecosystem functions. However, the drivers and their relative effects on the SIC stock at different soil depths remain largely unexplored. Here, we conducted a large-scale sampling to investigate the effects and relative contributions of abiotic (climate and soil) and biotic (plant and microbe) drivers on the SIC stock between topsoils (0–10 cm) and subsoils (20–30 cm) across Tibetan alpine grasslands. Results showed that the SIC stock had no significant differences between the topsoil and subsoil. The SIC stock showed a significant increase with altitude, pH and sand proportion, but declined with mean annual precipitation (MAP), plant aboveground biomass (PAB), plant coverage (PC), root biomass (RB), available nitrogen (AN), microbial biomass carbon (MBC), and bacterial abundance (BA) and fungal gene abundance (FA). For both soil layers, biotic factors had larger effects on the SIC stock than abiotic factors did. However, the relative importance of these determinants varied with soil depth, with the effects of plant and microbial variables on SIC stock weakening with soil depth, whereas the importance of climatic and edaphic variables increased with soil depth. Specifically, BA, FA and PC played dominant roles in regulating SIC stock in the topsoil, while soil pH contributed largely to the variation of SIC stock in the subsoil. Our findings highlight differential drivers over SIC stock with soil depth, which should be considered in biogeochemical models for better simulating and predicting SIC dynamics and its feedbacks to environmental changes.
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Niño-de-Guzman Tito, Michael, and Jesús Manuel Vásquez-Ramos. "Construction of an integral index based on macroinvertebrates to determine the quality of water with agro-industrial influence." Scientia Agropecuaria 13, no. 2 (May 18, 2022): 117–23. http://dx.doi.org/10.17268/sci.agropecu.2022.010.
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The physicochemical and biological indices have been used in isolation; if the parameters of these indices were applied in an integrated manner, they would bring together in a single measure the functional and structural variability of the biotic and abiotic components of water quality. The aim of this study was to build a comprehensive water quality index. Eleven sampling points were selected considering different degrees of agro-industrial intervention. 21 abiotic variables and 27 biological metrics were measured. Macroinvertebrates were quantitatively collected and identified to family taxonomic level. Using Principal Component Analysis, after standardization and exclusion of uncorrelated variables (VIF ≤ 10), the abiotic gradient was determined, which represented the abiotic variables that explained the disturbances in the water; with the abiotic gradient and the biological metrics, a Pearson correlation was performed, and those biological metrics that presented a high and non-redundant correlation were selected (Pearson 0.6 ≤ r ≤ 0.8); with the selected biological metrics, we proceeded to formulate and categorize the index; finally, by means of simple linear regression, the proposed index was compared with five other indexes (ICA, ICOMO, EPT, BMWP/col. and ASPT). The results showed that the abiotic gradient was defined by CP 1 which explained 65.5% of the accumulated variance, represented by altitude (r = 0.411), iron (r = 0.345) and dissolved oxygen (r = 0.329). The biological metrics used for the index design were: % scrapers, % swimmers, NEF of order 2, Ephemeroptera and Trichoptera tolerance. It was concluded that the integral index presents a higher predictive level (R2 = 0.87) of water quality, compared to the other indices: ASPT (R2 = 0.79), BMWP/col. (R2 = 0.68), EPT (R2 = 0.61), ICOMO (R2 = 0.35) and ICA (R2 = 0.27).
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Niño-de-Guzman Tito, Michael, and Jesús Manuel Vásquez-Ramos. "Construction of an integral index based on macroinvertebrates to determine the quality of water with agro-industrial influence." Scientia Agropecuaria 13, no. 2 (May 18, 2022): 117–23. http://dx.doi.org/10.17268/sci.agropecu.2022.010.
Full textAbstract:
The physicochemical and biological indices have been used in isolation; if the parameters of these indices were applied in an integrated manner, they would bring together in a single measure the functional and structural variability of the biotic and abiotic components of water quality. The aim of this study was to build a comprehensive water quality index. Eleven sampling points were selected considering different degrees of agro-industrial intervention. 21 abiotic variables and 27 biological metrics were measured. Macroinvertebrates were quantitatively collected and identified to family taxonomic level. Using Principal Component Analysis, after standardization and exclusion of uncorrelated variables (VIF ≤ 10), the abiotic gradient was determined, which represented the abiotic variables that explained the disturbances in the water; with the abiotic gradient and the biological metrics, a Pearson correlation was performed, and those biological metrics that presented a high and non-redundant correlation were selected (Pearson 0.6 ≤ r ≤ 0.8); with the selected biological metrics, we proceeded to formulate and categorize the index; finally, by means of simple linear regression, the proposed index was compared with five other indexes (ICA, ICOMO, EPT, BMWP/col. and ASPT). The results showed that the abiotic gradient was defined by CP 1 which explained 65.5% of the accumulated variance, represented by altitude (r = 0.411), iron (r = 0.345) and dissolved oxygen (r = 0.329). The biological metrics used for the index design were: % scrapers, % swimmers, NEF of order 2, Ephemeroptera and Trichoptera tolerance. It was concluded that the integral index presents a higher predictive level (R2 = 0.87) of water quality, compared to the other indices: ASPT (R2 = 0.79), BMWP/col. (R2 = 0.68), EPT (R2 = 0.61), ICOMO (R2 = 0.35) and ICA (R2 = 0.27).
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Hassan, A. N., M. A. Kenawy, H. Kamal, A. A. Abdel Sattar, and M. M. Sowilem. "GIS-based prediction of malaria risk in Egypt." Eastern Mediterranean Health Journal 9, no. 4 (September 21, 2003): 548–58. http://dx.doi.org/10.26719/2003.9.4.548.
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Environmental variables in a malaria geographic information system [GIS] database were analysed to discriminate between governorates at high and low risk of malaria. Only Fayoum governorate was categorized as a high risk area for malaria during the last 2 decades. Discriminant models correctly classified 96.3% of the risk categories and indicated that the most important predictor of risk is hydrogeology. Further GIS spatial analysis indicated that the high malaria risk in Fayoum is associated with a unique environmental envelope of biotic [presence of both efficient malaria vectors] and abiotic [hydrogeology and soil] variables. Recommendations for surveillance and control are discussed.
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Oliveira, Fábio Henrique Portella Corrêa de, Indira Maria Estolano Macedo, Marcelo Francisco dos Santos, Patrícia Karla Batista de Andrade, and Neide Kazue Sakugawa Shinohara. "Assessment of biotic and abiotic variables in water samples from the Metropolitan region of Recife (Pernambuco, Brazil)." Research, Society and Development 11, no. 5 (April 4, 2022): e21511528038. http://dx.doi.org/10.33448/rsd-v11i5.28038.
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The monitoring of water resources is essential to meet the vital needs of human beings in addition to being a resource that feeds lines of agro-industrial production and domestic use. The care of this natural resource is subject to several abiotic and biotic changes in reaction to anthropic stimuli. In this study, physical-chemical and microbiological tests were carried out on water samples from homes in the Metropolitan Region of Recife, evaluating the influences of pH, turbidity, alkalinity and chlorides on the presence and density of the microbiota present. The presence of total coliforms, Escherichia coli, Pseudomonas aeruginosa and heterotrophic bacteria were detected. Clostridium perfringens was absent in all samples. The results indicate that the presence of P. aeruginosa showed a negative relationship with turbidity values and a direct relationship with pH, chlorides and alkalinity. Higher chloride concentrations positively and negatively influence the density of coliform bacteria and heterotrophic bacteria, respectively. On the other hand, alkalinity negatively influenced the development of coliforms. The results indicate that the presence of P. aeruginosa showed a negative relationship with turbidity values and a direct relationship with pH, chlorides and alkalinity. Higher chloride concentrations positively and negatively influence the density of coliform bacteria and heterotrophic bacteria, respectively. On the other hand, alkalinity negatively influenced the development of coliforms. Results indicate that the analyzed waters are unsuitable due to the presence of P. aeruginosa, which in turn indicates lack of sanitation in the reservoirs and insufficient chlorination.
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Azouzi, L., E. Bourget, and D. Borcard. "Spatial variation in the intertidal bivalve Macoma balthica: biotic variables in relation to density and abiotic factors." Marine Ecology Progress Series 234 (2002): 159–70. http://dx.doi.org/10.3354/meps234159.
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