خيارات البحث
النتائج 1 - 10 من 22
The successions of plankton communities in Grosanica [water] reservoirs [Serbia, Yugoslavia]
1998
Comic, Lj. (Prirodno-matematicki fakultet, Novi Sad (Yugoslavia). Institut za biologiju) | Ostojic, A. | Milosevic, S. | Rankovic, B. | Simic, V. | Timotijevic, V. | Brdar, A.
Within the comprehensive hydrobiological investigation of Grosnica water reservoir (Serbia, Yugoslavia) composition and dynamics of bacterioplankton, phytoplankton and zooplankton, as well as their seasonal successions were studied. The composition of plankton communities varies during the vegetation period in the function of the physicochemical features. Grosnica water reservoir with its microbial features belongs to the 1st-2nd class of bonity according to Kohl. The highest values pf bacterio- and zooplankton were recorded in August, while bruto primary production in September.
اظهر المزيد [+] اقل [-]Water quality modeling and controlled successions of ichthyofauna
1998
Djordjevic, B. | Milanovic, T. (Univerzitet u Beogradu, Beograd (Yugoslavia). Gradjevinski fakultet)
Mathematical modles and adequate investigation works enables successful water quality modeling. These models includes all relevant abiotic components (concentration of dissolved oxygen, temperature regimes and temperature stratification, concentration of organic and inorganic components of physical-chemical water conditions), while the biotic components are present only with phyto- and zooplankton. In new water reservoir, ichthyofauna mostly undergo mancontrolled successions, starting with planned stocking a water reservoir with fish. The paper presents analytical approach for mathematical modeling of ichthyofauna and application of Lotka - Volterr's equations.
اظهر المزيد [+] اقل [-]The importance of some members of biocenosis in protecting the ecological balance on the preserved ecosystem Obedska bara [Serbia, Yugoslavia]
1997
Ratajac, R. (Poljoprivredni fakultet, Novi Sad (Yugoslavia)) | Rajkovic, D. | Stojkovic, S. | Bobic, M. | Cokic, S.
The investigations have been done in Krstonosica shaft at 3 points, in February, May and October 1995, and in January and April 1996. They included algae, Rotatoria, Copepoda, Cladocera, and Hydracarina. The species from divisio Bacillariophyta were presented most among the algal species, with 56 species, then from divisio Chlorophyta, with 26 taxons, Euglenophyta 11, Cyanobacteria 9, Pyrrophyta 3, Xanthophyta 2 and Chrysophyta 1. Among animal groups the highest number belonged to the Rotatoria group, 111 taxons have been determined. The highest number was found during autumn season (86), then in spring (73), and only 14 species in winter. The species that mostly prevailed were phytophyl species. The Cladocera group was present with 18 taxons. The phytophyl species from overgrown plants again prevailed. The Copepoda group was present with 10 species and the phytophyl species were prevailed. According to saprobiological characteristics the greatest number belongs to beta-mezosaprobionts, then oligosaprobionts. A small number of species indicates to the eutrophication process and organic pollution of water.
اظهر المزيد [+] اقل [-]Elevated cadmium pollution since 1890s recorded by forest chronosequence in deglaciated region of Gongga, China
2020
Wang, Xun | Luo, Ji | Lin, Che-Jen | Wang, Dingyong | Yuan, Wei
Ice and sediment cores, peat bogs and tree rings are useful proxy records for reconstructing historical air pollution events. However, these indirect measurements are subject to interferences caused by environmental perturbations including global climate change. Therefore, using multiple proxy records has advantages in constraining the analytical findings. In this study, we utilized the chronological record of atmospheric deposition preserved in vegetation succession ecosystems in the deglaciated region for reconstructing historical pollution events. The rate of Cd accumulation in the forest chronosequence zone was investigated in a deglaciated area of the Tibetan Plateau. The results obtained through this novel approach are consistent with the variations of Cd concentration recorded in tree-ring, showing a 4–7 times increase of atmospheric Cd deposition from the 1890s to the early 1970s followed by a decrease from the mid-1970s–2000s. The Cd pollution record indicates that elevated atmospheric Cd release occurred in regions of Southwest China and South Asia due to the rapid industrial development until 1970 followed by coordinated efforts in controlling air emissions after mid-1970s.
اظهر المزيد [+] اقل [-]Surface coatings select their micro and macrofouling communities differently on steel
2019
Agostini, Vanessa Ochi | Macedo, Alexandre José | Muxagata, Erik | Pinho, Grasiela Lopes Leães
Previous studies have shown the effect of surface coatings on biofouling; however, they did not take into account the interaction of the micro and macrofouling communities, the effect of substrate orientation and the zooplankton-zoobenthic coupling together. Therefore, the aim of this study was to evaluate the effect of Zn- and Cu₂O-based coatings on micro and macrofouling on steel surfaces, while also observing the role of substrate orientation and zooplankton supply. An experiment was carried out in the Patos Lagoon Estuary in southern Brazil for three months between spring and summer, where ASTM-36 steel plates represented different coatings (Zn- and/or Cu₂O-based) and orientations (vertical and horizontal). To assess the zooplankton supply, sampling was carried out weekly using a 200 μm plankton net. Zn-based coating positively affected microfouling density compared to uncoated surfaces. The same pattern was observed with macrofouling, associated with vagile fauna preference, which represented 70% of the settled macrofoulers. Cu₂O-based antifouling painted surfaces showed the highest microfouling density inhibition, while Zn + Cu₂O-based coating did not affect the bacteria adhesion but showed lower density compared to Zn-based coating alone. The coatings combination showed the highest invertebrate inhibition. In this way, the macrofouling community was more sensitive than microfouling was to the antifouling coatings tested. The substrate orientation only affected macrofouling, horizontal surfaces being more attractive than vertical. Meroplankton, tychoplankton and holoplankton were recorded on the surfaces, although their representation in plankton was not proportional to the recruits recorded on the substrates. This was probably due to fast dispersion, the interactions of other factors and/or ecological succession stage. Surface coating, substrate orientation, and zooplankton supply interacted with the biofouling process on steel in different ways depending on the organism evaluated. Therefore, copper oxide- and zinc-based coatings were not suitable as coatings to avoid the total biofouling establishment.
اظهر المزيد [+] اقل [-]The importance of edaphic niches and pioneer plant species succession for the phytomanagement of mine tailings
2013
Parraga-Aguado, Isabel | Gonzalez-Alcaraz, Maria Nazaret | Alvarez-Rogel, Jose | Jimenez-Carceles, Francisco J. | Conesa, Hector M.
Phytomanagement in terms of phytostabilisation is considered a suitable method to decrease environmental risks of metal(loid) enriched mine tailings. The goal of this study was to identify plant-favourable edaphic niches in mine tailings from a semiarid area, in order to obtain relevant information for further phytostabilisation procedures. For this purpose, a transect-designed sampling from non-disturbed soils to two mine tailings was performed, including the description of soil and plant ecology gradients. Plant ecological indicators showed several stages in plant succession: from weeds to stable patches of late successional plant species. PCA results revealed that plant distribution at the tailings was driven mainly by salinity while metal(loid) concentrations played a minor role. The presence of soil desiccation cracks generated low salinity patches which facilitated favourable niches for plant establishment. Edaphic-patch distribution may condition phytostabilisation since ploughing or the employment of certain amendments should take into account favourable niches for plant growth.
اظهر المزيد [+] اقل [-]Effects of organic pollution on biological communities of marine biofilm on hard substrata
2015
Sanz-Lázaro, C. | Fodelianakis, S. | Guerrero-Meseguer, L. | Marin, A. | Karakassis, I.
We examined the effect of organic enrichment on diatom and bacterial assemblages of marine epilithic biofilms on two locations in the Mediterranean, one situated in Spain and the other in Greece. Total organic carbon, total organic nitrogen, stable isotopes (δ13C and δ15N) and chlorophyll a indicated significant incorporation of organic wastes, increased primary production and trophic niche modifications on the biofilms close to the organic enrichment source. In Spain, where the organic load was higher than in Greece, diatom and, to some extent, bacterial assemblages varied following the organic enrichment gradient. The taxonomic richness of diatom and bacterial communities was not influenced by organic enrichment. Classical community parameters showed consistent patterns to organic pollution in both locations, whereas community assemblages were only influenced when organic pollution was greatest. The successional patterns of these communities were similar to other epilithic communities. The modification of community assemblages induced by organic pollution may affect ecological functions.
اظهر المزيد [+] اقل [-]A succession of marine bacterial communities in batch reactor experiments during the degradation of five different petroleum types
2020
Cerqueda-García, Daniel | García-Maldonado, José Q. | Aguirre-Macedo, Leopoldina | García-Cruz, Ulises
Marine microbial communities might be subjected to accidental petroleum spills; however, some bacteria can degrade it, making these specific bacteria valuable for bioremediation from petroleum contamination. Thus, characterizing the microbial communities exposed to varying types of petroleum is essential. We evaluated five enriched microbial communities from the northwest Gulf of Mexico (four from the water column and one from sediments). Enrichments were performed using five types of petroleum (extra light, light, medium, heavy and extra heavy), to reveal the microbial succession using a 16S rDNA amplicon approach. Four communities were capable of degrading from extra light to heavy petroleum. However, only the community from sediment was able to degrade the extra heavy petroleum. Successional changes in the microbial communities' structures were specific for each type of petroleum where genus Dietzia, Gordonia, Microvirga, Rhizobium, Paracoccus, Thalassobaculum, Sphingomonas, Moheibacter, Acinetobacter, Pseudohongiella, Porticoccus, Pseudoalteromonas, Pseudomonas, Shewanella, and Planctomyces presented differential abundance between the treatments.
اظهر المزيد [+] اقل [-]Anaerobic degradation of high-concentration polycyclic aromatic hydrocarbons (PAHs) in seawater sediments
2021
Mu, Jun | Leng, Qingxue | Yang, Guangfeng | Zhu, Baikang
Recurring oil spill accidents have been a global challenge and contribute to PAHs' heavy accumulation in marine sediments. The rapid bioremediation of PAHs with high concentrations in marine sediments has rarely been studied. In this study, four representative PAHs in crude oil were tested for fast anaerobic biodegradation. An efficient system for the anaerobic degradation of high-concentration PAHs was obtained using petroleum-acclimated marine sediments as inoculants in the treatment system. The degradation efficiencies of benzo[b]fluoranthene, benzo[a]pyrene, pyrene, and phenanthrene reached 0.21, 1.71, 3.89, and 4.10 mg/(L·d), respectively, which are 16, 2.8, 1.8, and 1.0 times higher than the reported values. Nitrate was preferred to sulfate as an electron acceptor. The acclimated sediment contains a high abundance of hydrocarbon-degrading bacteria. The number and diversity of species in the treatment system supplemented with PAHs decreased, but the abundance of some hydrocarbon-degrading bacteria and hydrocarbon-intermediate utilising bacteria increased, and ecological succession was observed.
اظهر المزيد [+] اقل [-]Comparison of photosynthetic responses to manganese toxicity of deciduous broad-leaved trees in northern Japan
1997
Kitao, M. | Lei, T.T. | Koike, T. (Forestry and Forest Products Research Institute, Hokkaido Research Center, Sapporo 062 (Japan))