Search results for "Brachionus calyciflorus"
showing 10 items of 18 documents
Diapause as escape strategy to exposure to toxicants: response of Brachionus calyciforus to arsenic
2016
Invertebrate organisms commonly respond to environmental fluctuation by entering diapause. Production of diapause in monogonont rotifers involves a previous switch from asexual to partial sexual reproduction. Although zooplankton have been used in ecotoxicological assays, often their true vulnerability to toxicants is underestimated by not incorporating the sexual phase. We experimentally analyzed traits involved in sexual reproduction and diapause in the cyclically parthenogenetic freshwater rotifer, Brachionus calyciflorus, exposed to arsenic, a metalloid naturally found in high concentrations in desert zones, focusing on the effectiveness of diapause as an escape response in the face of …
Effect of pentachlorophenol on predator-prey interaction of two rotifers
1997
Abstract The effect of pentachlorophenol (PCP) on the predator-prey relationship of two rotifers (Asplanchna girodi and Brachionus calyciflorus) was studied using Asplanchna predatory behavior as an endpoint. The experimental design included three treatments: prey and predator exposure, only prey exposure, and only predator exposure. This enabled us to distinguish toxic effects on the predator from those on the prey and to detect interactions. The main toxic effects observed were on the predator and involved the number of predator-prey encounters. Encounters decreased in a dose-dependent manner, with a no observed effect threshold at 0.11 mg PCP l−1. Decrease in encounter rate reduced the n…
Ecotoxicological studies with the freshwater rotifer Brachionus calyciflorus. Resource competition between rotifers and daphnids under toxic stress
1993
Abstract This study examined the ability of the freshwater rotifer Brachionus calyciflorus to coexist with the large cladoceran Daphnia magna, and the effect of sublethal concentrations of copper on the competition between both species. Preliminary laboratory experiments showed that large Daphnia (> 1.2 mm) can kill and rapidly exclude the rotifer B. calyciflorus in mixed-species cultures. Brachionus populations were suppressed by Daphnia both through exploitative competition for shared, limited food resources and through mechanical interference. At a food concentration of 1 X 105 cells/ml of Nannochloris oculata, competition caused high mortality rates and decreased fertility in the rotife…
Effect of the insecticide methylparathion on filtration and ingestion rates of Brachionus calyciflorus and Daphnia magna
1993
The freshwater rotifer Brachionus calyciflorus and the cladocera Daphnia magna were exposed to sublethal levels of methylparathion to determine the effect on filtration and ingestion rates. The experiments were performed using the unicellular algae, Nannochloris oculata in a density of 5 × 105 cell/ml. Prior to feeding experiments, preliminary acute toxicity tests were carried out to determine 24-h LC50 values for both species, these values indicated that Daphnia magna was more sensitive to methylparathion acute exposure than Brachionus calyciflorus was. Rates of filtration and ingestion declined with increasing methylparathion concentrations after an exposure of 5 h to this toxicant. The e…
Demographic parameters of Brachionus calyciflorus Pallas (Rotifers) exposed to sublethal endosulfan concentrations
1991
The effects of sublethal levels of endosulfan (0, 1, 1.5, 2.5 and 3.3 mg 1−1) on the demography of the rotifer Brachionus calyciorus were studied. Life expectancy at birth (e o), net reproductive rate (Ro), generation time (T) and intrinsic rate of natural increase (r) were significant differentes between blank controls and controls with acetone. The effective endosulfan concentration at which a given parameter value was reduced to 50% of the controls (EC50) was calculated for life expectancy.
Application of Toxkit microbiotests for toxicity assessment in soil and compost
2004
The potential of Toxkit microbiotests to detect and analyze pollution in agricultural soil and the quality of compost was studied. The toxicity tests used included seed germination biotests using cress salad (Lepidum sativum L.), tomato (Lycopersicum esculentum L.), and cucumber (Cucumis sativus L.), and the Toxkit microbiotests included those with microalgae (Selenastrum capricornutum), protozoa (Tetrahymena thermophila), crustaceans (Daphnia magna, Thamnocephalus platyurus, and Heterocypris incongruens), and rotifers (Brachionus calyciflorus). Experiments on compost were undertaken in a modified solid-state fermentation system (SSF) and under field conditions (in a windrow). To promote th…
Acute toxicity of toluene, hexane, xylene, and benzene to the rotifers Brachionus calyciflorus and Brachionus plicatilis.
1992
A large number of studies on the biological effects of oil pollution in the aquatic environment deal with the effects of whole crude or refined oils or their water-soluble fractions. However, low boiling, aromatic hydrocarbons, which are probably the most toxic constituents of oil, have until now not been examined in sufficient detail. Toluene, benzene and xylene, constitute a major component of various oils. They may be readily lost by weathering but are toxic in waters that are relatively stagnant and are chronically polluted. Korn et al. have stated that toluene is more toxic than many other hydrocarbons such as benzene, though the latter are more water-soluble. Report of the effects of …
Acute lethal toxicity of some pesticides toBrachionus calyciflorus andBrachionus plicatilis
1991
Due to their widespread distribution and toxic nattwe pesticides may have a serious impact on the aquatic environment and exert adverse effects on the associated organisms. Acute bioassay tests have been used to determine the actual impact of various pesticides on aquatic life. Static acute toxicity tests provide rapid and reproductible concentration-response curves for estimating toxic effects of chemicals on aquatic organisms. These tests provide a data base for determining relative toxicity to a variety of species.
Comparative toxicant sensitivity of sexual and asexual reproduction in the rotiferBrachionus calyciflorus
1995
Cyclically parthenogenetic zooplankters like rotifers are important tools for assessing toxicity in aquatic environments. Sexual reproduction is an essential component of rotifer life cycles, but current toxicity tests utilize only asexual reproduction. The authors compared the effects of four toxicants on asexual and sexual reproduction of the rotifer Brachionus calyciflorus. Toxicants had a differential effect on sexual and asexual reproduction, with sexual reproduction consistently the most sensitive. Concentrations of 0.2 {mu}g/ml PCP (sodium pentachlorophenate) had no effect on the asexual reproductive rate, but significantly reduced sexual reproduction. Likewise, chlorpyrifos concentr…
Chronic toxicity of fenitrothion to an algae (Nannochloris oculata), a rotifer (Brachionus calyciflorus), and the cladoceran (Daphnia magna).
1996
Chronic toxicity studies were conducted with an algae (Nannochloris oculata), a rotifer (Brachionus calyciflorus), and a cladoceran (Daphnia magna) to determine their relative sensitivities to the organophosphorus insecticide fenitrothion. The cladoceran D. magna was the most sensitive of the three species. The no observed effect concentrations (NOECs) for the study with the algae (1.0 mg/liter) and for the rotifer (1.0 mg/liter) were higher than the NOEC (0.009 microgram/liter) and the LC50 of 24 hr (0.067 microgram/liter) for D. magna. Most of the algal populations were not initially affected by exposure to fenitrothion. Pesticide concentrations higher than 1.0 mg/liter significantly redu…