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Chronic Toxicity
Chronic toxicity, the development of adverse effects as a result of long term exposure to a contaminant or other stressor, is an important aspect of aquatic toxicology. Adverse effects associated with chronic toxicity can be directly lethal but are more commonly sublethal, including changes in growth, reproduction, or behavior. Chronic toxicity is in contrast to acute toxicity, which occurs over a shorter period of time to higher concentrations. Various toxicity tests can be performed to assess the chronic toxicity of different contaminants, and usually last at least 10% of an organism's lifespan. Results of aquatic chronic toxicity tests can be used to determine water quality guidelines and regulations for protection of aquatic organisms. Definition Chronic toxicity is the development of adverse effects as the result of long term exposure to a toxicant or other stressor. It can manifest as direct lethality but more commonly refers to sublethal endpoints such as decreased growth, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquatic Toxicology
Aquatic toxicology is the study of the effects of manufactured chemicals and other anthropogenic and natural materials and activities on aquatic organisms at various levels of organization, from subcellular through individual organisms to communities and ecosystems. Aquatic toxicology is a multidisciplinary field which integrates toxicology, aquatic ecology and aquatic chemistry. This field of study includes freshwater, marine water and sediment environments. Common tests include standardized acute and chronic toxicity tests lasting 24–96 hours (acute test) to 7 days or more (chronic tests). These tests measure endpoints such as survival, growth, reproduction, that are measured at each concentration in a gradient, along with a control test. Typically using selected organisms with ecologically relevant sensitivity to toxicants and a well-established literature background. These organisms can be easily acquired or cultured in lab and are easy to handle. History While basic re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acute Toxicity
Acute toxicity describes the adverse effects of a substance that result either from a single exposure or from multiple exposures in a short period of time (usually less than 24 hours). To be described as ''acute'' toxicity, the adverse effects should occur within 14 days of the administration of the substance. Acute toxicity is distinguished from chronic toxicity, which describes the adverse health effects from repeated exposures, often at lower levels, to a substance over a longer time period (months or years). It is widely considered unethical to use humans as test subjects for acute (or chronic) toxicity research. However, some information can be gained from investigating accidental human exposures (e.g., factory accidents). Otherwise, most acute toxicity data comes from animal testing or, more recently, ''in vitro'' testing methods and inference Inferences are steps in logical reasoning, moving from premises to logical consequences; etymologically, the word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pimephales Promelas
Fathead minnow (''Pimephales promelas''), also known as fathead or tuffy, is a species of freshwater ray-finned fish belonging to the family Leuciscidae, the shiners, daces and minnows. The natural geographic range extends throughout much of North America, from central Canada south along the Rockies to Texas, and east to Virginia and the Northeastern United States.Page, Lawrence M. and Brooks M. Burr (1991), ''Freshwater Fishes'', p. 129–130, Houghton Mifflin, New York, NY. This minnow has also been introduced to many other areas via bait bucket releases. Its golden, or xanthic, strain, known as the rosy-red minnow, is a very common feeder fish sold in the United States and Canada. This fish is also known for producing Schreckstoff (a distress signal). Physical description The fathead minnow in its wild form is generally dull olive-grey in appearance, with a dusky stripe extending along the back and side, and a lighter belly. There is a dusky blotch midway on the dorsal fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Magna
''Daphnia magna'' is a small planktonic crustacean (adult length 1.5–5.0 mm) that belongs to the subclass Phyllopoda. Description ''Daphnia magna'' is a typical water flea of the genus ''Daphnia''. The females reach up to 5 mm in size, the males about 2 mm, thus they are among the largest species in the genus. The body is protected by a translucent carapace made of chitin, a transparent polysaccharide. It has a ventral opening and five pairs of thoracic limbs, used to help the filtering process. Spike rows run along the back of the carapace. The intestine is hook-shaped and has two digestive ceca. The head has two antennae and a large compound eye. Adult females can be distinguished from those of otherwise similar species such as '' D. pulex'' by the absence of a comb on the abdominal claw and the presence of two distinct combs on the abdomen. The males are smaller than the females and have larger first antennas, a diagnostic feature that distinguishes them ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raphidocelis Subcapitata
''Raphidocelis subcapitata'', formerly known as ''Selenastrum capricornutum'' and ''Pseudokirchneriella subcapitata'' is a microalga. This microalga presents a curved and twisted appearance like a sickle. The cells are normally presented in a solitary form in culture, although it may also be present in small colonies. It has a length between 7 and 15 μm, and a width between 1.2 and 3 μm. A single chloroplast is present, filling nearly the entire cell; it lacks a pyrenoid. It is commonly used as a bioindicator species to assess the levels of nutrients or toxic substances in fresh water environments. This species is quite sensitive to the presence of toxic substances including metals and has a ubiquitous distribution, so is broadly used in ecotoxicology. This species has been found to be more competitive than ''Chlorella vulgaris ''Chlorella vulgaris'' is a species of green microalga in the division Chlorophyta. This unicellular alga was discovered in 1890 by Martin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyalella Azteca
''Hyalella azteca'' is a widespread and abundant species complex of amphipod crustacean in North America. It reaches long, and is found in a range of fresh and brackish waters. It feeds on algae and diatoms and is a major food of waterfowl. Description ''Hyalella azteca'' has body plan similar to most Amphipoda, amphipods and is a classic freshwater example of the order. They grow to a length of , with males being larger than females. Their color is variable, but the most frequent hues are white, green and brown. They are identified from other similar species by antenna 1 being equal or shorter than antenna 2, 1 spine on pleosome 1 and pleosome 2, Pereopod I and II are gnathopod with males having a visibly larger gnathopod. Distribution ''Hyalella azteca'' is found across Central America, the Caribbean and North America, as far north as the Arctic tree line. It lives among vegetation and sediments in permanent bodies of freshwater, including lakes and rivers, extending into tid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maximum Overdrive Toxicant Concentration
In mathematical analysis, the maximum and minimum of a function are, respectively, the greatest and least value taken by the function. Known generically as extremum, they may be defined either within a given range (the ''local'' or ''relative'' extrema) or on the entire domain (the ''global'' or ''absolute'' extrema) of a function. Pierre de Fermat was one of the first mathematicians to propose a general technique, adequality, for finding the maxima and minima of functions. As defined in set theory, the maximum and minimum of a set are the greatest and least elements in the set, respectively. Unbounded infinite sets, such as the set of real numbers, have no minimum or maximum. In statistics, the corresponding concept is the sample maximum and minimum. Definition A real-valued function ''f'' defined on a domain ''X'' has a global (or absolute) maximum point at ''x''∗, if for all ''x'' in ''X''. Similarly, the function has a global (or absolute) minimum point at ''x''∗, if ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predicted No-effect Concentration
The predicted no-effect concentration (PNEC) is the concentration of a chemical which marks the limit at which below no adverse effects of exposure in an ecosystem are measured. PNEC values are intended to be conservative and predict the concentration at which a chemical will likely have no toxic effect. They are not intended to predict the upper limit of concentration of a chemical that has a toxic effect.European Chemicals Bureau. (2003) Technical Guidance Document on Risk Assessment. European CommunitiesPredicted No Effect Concentration. 2015. Greenfacts. Available online at: http://www.greenfacts.org/glossary/pqrs/PNEC-predicted-no-effect-concentration.htm PNEC values are often used in environmental risk assessment as a tool in ecotoxicology.Manuilova, A. (2003)Methods and Tools Available for Assessment of Environmental Risk. Dantes. A PNEC for a chemical can be calculated with acute toxicity or chronic toxicity single-species data, Species Sensitivity Distribution (SSD) multi-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acute To Chronic Ratio
The acute to chronic ratio (ACR) uses acute toxicity data to gauge the chronic toxicity (MATC) of a chemical of interest to an organism. The science behind determining a safe concentration to the environment is imperfect, statistically limited, and resource intensive. There is an unfilled demand for the rapid assessment of different chemical toxicity to many different organisms. The ACR is a proposed solution to this demand. While empirical methods are crucial to making scientific conclusions and informed decisions, best personal judgement is often the best tool to the regulator in allowing or prohibiting potentially toxic chemicals from entering the environment. This means taking into consideration information about chemical structure, physical and chemical properties including fate and transport in the environment, and most importantly toxicological data. The ACR is mathematically the inverse of the application factor (AF), which was first proposed by Mount and Stephan (196 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotic Ligand Model
Biotics describe living or once living components of a community; for example organisms, such as animals and plants. Biotic may refer to: *Life, the condition of living organisms *Biology, the study of life *Biotic material, which is derived from living organisms *Biotic components in ecology * Biotic potential, an organism's reproductive capacity * Biotic community, all the interacting organisms living together in a specific habitat * Biotic energy, a vital force theorized by biochemist Benjamin Moore * Biotic Baking Brigade, an unofficial group of pie-throwing activists See also *Abiotic *Antibiotics are agents that either kill bacteria or inhibit their growth *Prebiotic (nutrition) are non-digestible food ingredients that stimulate the growth or activity of bacteria in the digestive system *Probiotic Probiotics are live microorganisms that provide health benefits when consumed, generally by improving or restoring the microbiota in the gut. Probiotics are considered ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquatic Toxicology
Aquatic toxicology is the study of the effects of manufactured chemicals and other anthropogenic and natural materials and activities on aquatic organisms at various levels of organization, from subcellular through individual organisms to communities and ecosystems. Aquatic toxicology is a multidisciplinary field which integrates toxicology, aquatic ecology and aquatic chemistry. This field of study includes freshwater, marine water and sediment environments. Common tests include standardized acute and chronic toxicity tests lasting 24–96 hours (acute test) to 7 days or more (chronic tests). These tests measure endpoints such as survival, growth, reproduction, that are measured at each concentration in a gradient, along with a control test. Typically using selected organisms with ecologically relevant sensitivity to toxicants and a well-established literature background. These organisms can be easily acquired or cultured in lab and are easy to handle. History While basic re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
