Search results for "freshwater"
showing 10 items of 285 documents
Effect of multiple agricultural stressors on freshwater ecosystems: The role of community structure, trophic status, and biodiversity-functioning rel…
2022
Abstract The toxicity and widespread use of agricultural pesticides threaten freshwater biodiversity, but their long-term effects under different nutrient concentrations are poorly understood. We evaluated the single or combined effects of two pesticides (chlorpyrifos and diuron) under different nutrient regimes (mesotrophic and eutrophic) on community structure and ecosystem functions in replicated pond mesocosms. The individual application of nutrients and pesticides affected community composition and species richness. Ecosystem functioning was generally less sensitive to chemical stress than community structure, while eutrophication fostered the dominance of species that are more resilie…
Ecological risk assessment of pesticides in urban streams of the Brazilian Amazon
2022
Abstract The use of pesticides in households and peri-urban areas of the Amazon has increased notably during the last years. Yet, the presence of these contaminants in Amazonian freshwater ecosystems remains unexplored. Here, we assessed the exposure to 18 pesticides and 5 transformation products in the Amazon River and in the urban streams of Manaus, Santarem, Macapa, and Belem (Brazil). Pesticide concentrations were analyzed by liquid and gas chromatography methods. Ecological risks were assessed following a two-tiered approach. First, hazard quotients and an overall hazard index were calculated using toxicity data for standard test species of primary producers, invertebrates, and fish. S…
Patterns of presence and concentration of pesticides in fish and waters of the Júcar River (Eastern Spain).
2013
The Jucar River, in a typical Mediterranean Basin, is expected to suffer a decline in water quality and quantity as a consequence of the climate change. This study is focused on the presence and distribution of pesticides in water and fish, using the first extensive optimization and application of the QuEChERS method to determine pesticides in freshwater fish. Majority pesticides in water - in terms of presence and concentration - were dichlofenthion, chlorfenvinphos, imazalil, pyriproxyfen and prochloraz (associated with a frequent use in farming activities), as well as buprofezin, chlorpyriphos and hexythiazox. In fish, the main compounds were azinphos-ethyl, chlorpyriphos, diazinon, dime…
Subsecond pore‐scale displacement processes and relaxation dynamics in multiphase flow
2014
With recent advances at X‐ray microcomputed tomography (μCT) synchrotron beam lines, it is now possible to study pore‐scale flow in porous rock under dynamic flow conditions. The collection of four‐dimensional data allows for the direct 3‐D visualization of fluid‐fluid displacement in porous rock as a function of time. However, even state‐of‐the‐art fast‐μCT scans require between one and a few seconds to complete and the much faster fluid movement occurring during that time interval is manifested as imaging artifacts in the reconstructed 3‐D volume. We present an approach to analyze the 2‐D radiograph data collected during fast‐μCT to study the pore‐scale displacement dynamics on the time s…
The impact of various cations on the sorption of manganese in the thallus of freshwater algae spirogyra sp. and sea algae palmaria palmata
2014
Abstract Due to their occurrence in very different conditions and high resistance to physical and chemical factors, algae are pioneers colonising new environments and their sorption properties are used in biomonitoring and water remediation. The efficiency of the process of heavy metal sorption in algae used for in situ tests depends on abiotic factors, such as the chemical composition of water. Freshwater algae Spirogyra sp. were used in tests. Algae were exposed in the laboratory in manganese chloride solutions with various contents of other cations, including heavy metals and macronutrients. It has been shown that some heavy metals may desorb manganese bound to the surface of algae as a …
Characterization of the contamination fingerprint of wastewater treatment plant effluents in the Henares River Basin (central Spain) based on target …
2022
The interest in contaminants of emerging concern (CECs) has increased lately due to their continued emission and potential ecotoxicological hazards. Wastewater treatment plants (WWTPs) are generally not capable of eliminating them and are considered the main pathway for CECs to the aquatic environment. The number of CECs in WWTPs effluents is often so large that complementary approaches to the conventional target analysis need to be implemented. Within this context, multitarget quantitative analysis (162 compounds) and a suspect screening (>40,000 suspects) approaches were applied to characterize the CEC fingerprint in effluents of five WWTPs in the Henares River basin (central Spain) durin…
Saprophytism of a fish pathogen as a transmission strategy
2009
Fish farming creates conditions where disease transmission is enhanced and antibiotic treatments are commonly used to cure bacterial diseases to prevent severe losses due to infections. Ability to persist in such an environment has been suggested to lead to the evolution of high virulence. Columnaris disease caused by Flavobacterium columnare is a growing problem in freshwater fish farming. Transmission of the disease is poorly known, and survival of F. columnare in the rearing environment has not been studied. This paper addresses both transmission of columnaris disease and survival strategy of F. columnare. Saprophytic activity of F. columnare was studied by infecting rainbow trout finger…
Fascioliasis transmission by Lymnaea neotropica confirmed by nuclear rDNA and mtDNA sequencing in Argentina
2009
Fascioliasis is widespread in livestock in Argentina. Among activities included in a long-term initiative to ascertain which are the fascioliasis areas of most concern, studies were performed in a recreational farm, including liver fluke infection in different domestic animal species, classification of the lymnaeid vector and verification of natural transmission of fascioliasis by identification of the intramolluscan trematode larval stages found in naturally infected snails. The high prevalences in the domestic animals appeared related to only one lymnaeid species present. Lymnaeid and trematode classification was verified by means of nuclear ribosomal DNA and mitochondrial DNA marker sequ…
Sogdatawa ǝtumǝciusu
1934
Apskats par zivīm un zvejniecību nanaju (goldu) valodā.
Genetic-based evaluation of management units for sustainable vendace (Coregonus albula) fisheries in a large lake system
2022
Abstract The goal of the processing industry, trade and consumers is to get eco-labelled freshwater fish products from sustainable fisheries into the market as soon as possible. The fourth largest natural lake system in Europe, the Saimaa lake system supports a fishery for vendace (Coregonus albula). Certification of the fishery requires an understanding of population structure to help determine the number and spatial extent of management units. In this study, we analysed the genetic diversity of local vendace populations in the Saimaa lake system and aimed to identify the conservation and management units of vendace. Within the Saimaa, the genetic divergence between local populations of ve…