Search results for "Fresh Water"
showing 10 items of 190 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…
The toxicity and concentrations of PAHs in creosote-contaminated lake sediment
1999
Sediment samplers, divided into three layers (0 – 10, 10 – 20 and 20 – 30 cm), were collected from 16 sites in Lake Jamsanvesi, Central Finland. The acute toxicity of pore waters and elutriates (sediment + water 1:4 v/v) were studied by bioluminescence inhibition test and by immobilisation of water fleas (Daphnia magna Straus). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediments and elutriates were measured by gas chromatography using flame ionization detection (GC/FID). The highest total PAH concentration was 3.3 mg/g dry weight in the sediment and up to 1.7 mg/l in the elutriate of the uppermost (0 – 10 cm) layer, also being the most toxic to photoluminencent bacteria, …
Energy reserves mobilization in the yellow eel as herbicide exposure effect.
2015
Abstract Thiobencarb and propanil are two of the most extensive used herbicides worldwide in rice cultivation. Especially scanty is the available information regarding the effect of herbicides on fish energy resources. In the present study, the effect of sublethal exposure to these herbicides on the energy reserves of juvenile eel Anguilla anguilla was compared. Eels were exposed to 72 h to the herbicide thiobencarb (0.22 mg L −1 ) or Propanil (0.63 mg L −1 ), and allowed to recover in clean water (144 h). Caloric content was determined in liver and skeletal muscle. Fish exposed to thiobencarb rapidly mobilized energy. Reserves from liver were depleted (21%) compared to control values (2.50…
A parsimonious dynamic model for river water quality assessment
2010
Water quality modelling is of crucial importance for the assessment of physical, chemical, and biological changes in water bodies. Mathematical approaches to water modelling have become more prevalent over recent years. Different model types ranging from detailed physical models to simplified conceptual models are available. Actually, a possible middle ground between detailed and simplified models may be parsimonious models that represent the simplest approach that fits the application. The appropriate modelling approach depends on the research goal as well as on data available for correct model application. When there is inadequate data, it is mandatory to focus on a simple river water qua…
Superoxide-driven autocatalytic dark production of hydroxyl radicals in the presence of complexes of natural dissolved organic matter and iron.
2019
Abstract We introduced superoxide as potassium superoxide (KO2) to artificial lake water containing dissolved organic matter (DOM) without or with introduced ferric iron complexes (DOM-Fe(III)), and monitored the production rate of hydroxyl radicals as well as changes in the absorption and fluorescence properties of DOM. The introduction of KO2 decreased the absorption by DOM but increased the spectral slope coefficient of DOM more with complexed ferric Fe than without it. The introduction of KO2 increased the fluorescence of humic-like components in DOM without introduced ferric Fe but resulted in the loss of fluorescence in DOM with introduced ferric Fe. A single introduction of 13 μmol L…
Quantifying submarine groundwater discharge in the coastal zone via multiple methods
2006
Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. As such, this flow may contribute to the biogeochemical and other marine budgets of near-shore waters. These discharges typically display significant spatial and temporal variability making assessments difficult. Groundwater seepage is patchy, diffuse, temporally variable, and may involve multiple aquifers. Thus, the measurement of its magnitude and associated chemical fluxes is a challenging enterprise. A joint project of UNESCO and the International Atomic Energy Agency (IAEA) has examined several methods of SGD assessment and carried out a series of five intercomparison experiments in di…
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…
The valid genus name of the European freshwater blennies, Ichthyocoris or Salariopsis (Teleostei: Blenniidae)?
2022
Vecchioni, Luca, Arculeo, Marco, Hundt, Peter J., Marrone, Federico (2022): The valid genus name of the European freshwater blennies, Ichthyocoris or Salariopsis (Teleostei: Blenniidae)? Zootaxa 5162 (1): 99-100, DOI: https://doi.org/10.11646/zootaxa.5162.1.8
Lethal toxicity of Lindane on a teleost fish,Anguilla anguillafrom albufera lake (Spain): Hardness and temperature effects
1988
This paper reports the results of toxicity tests conducted using Anguilla anguilla under three different water temperature (15, 22 and 29 degrees C) and two hardness regimes (250 and greater than 600 ppm CaCO3). The 96-h LC50 increased in the experimental medium (p less than 0.05) by an order of magnitude from 0.32 to 0.45 mg/L between 15 and 29 degrees C. However in the natural medium it is similar (p greater than 0.05) (0.54 to 0.55 mg/L) for these same temperatures. The toxicity of Lindane on eels increased when the water hardness decreased. The 24, 48, 72 and 96-h LC50 for this fish in both media is less at 15 degrees C (96-h LC50 = 0.32 and 0.55 mg/L) than at 29 degrees C (96-h LC50 = …
Outside-host growth of pathogens attenuates epidemiological outbreaks.
2012
Opportunist saprotrophic pathogens differ from obligatory pathogens due to their capability in host-independent growth in environmental reservoirs. Thus, the outside-host environment potentially influences host-pathogen dynamics. Despite the socio-economical importance of these pathogens, theory on their dynamics is practically missing. We analyzed a novel epidemiological model that couples outside-host density-dependent growth to host-pathogen dynamics. Parameterization was based on columnaris disease, a major hazard in fresh water fish farms caused by saprotrophic Flavobacterium columnare. Stability analysis and numerical simulations revealed that the outside-host growth maintains high pr…