Toxicity to algae

Like daphnids, algae occur ubiquitously in aquatic ecosystems and they are an important link in aquatic foodwebs. The test species are generally fastgrowing strains of unicellular green algae, which are easy to culture in the laboratory for example, Selenastrum capricomutum, Scenedesmus subspica-tus and Chlorella vulgaris. 

Duration of the test sensitivity to chemicals may increase or decrease with changes in the test period due to alterations in the catabolic status and in the defence mechanisms of the cultures. 

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BASE SET Mutagenicity Toxicity to reproduction Toxicity to algae Acute daphnia and fish toxicity Abiotic and readily biotic degradability Additional physico-chemical properties 1 t/annum or 5 t cumulative... 

Hutchinson TC, Hellebust JA, Tam D et al. 1980. The correlation of the toxicity to algae of hydrocarbons and halogenated hydrocarbons with their physical-chemical properties. In Afghan BK, MacDay D, eds. Hydrocarbons and Halogenated Hydrocarbons in the Aquatic Environment. New York Plenum Press, 577-586. 

Wong, P.T.S. and J.T. Trevors. 1988. Chromium toxicity to algae and bacteria. Pages 305-315 in J.O. Nriagu and E. Nieboer (eds.). Chromium in Natural and Human Environments. John Wiley, NY. 

Gala, W.R. Giesy, J.P. Flow c3dometric techniques to assess toxicity to algae. In Aquatic Toxicology and Risk Assessment, Landis, W., Vander SchaUe, W.H., Eds. ASTM Philadelphia, PA, 1993 Vol. 13, 237-246. 

Trifluoroacetic acid has been shown to impact sensitive species of algae, such as Raphidocelis subcapitata, with a lowest observed effective dose of 360 xg/l [236]. Most plant species tested were impacted by trifluoroacetic acid at concentrations in the mg/1 range [236,240]. Although these toxic concentrations are 2 - 3 orders of magnitude higher than typical current environmental levels [237-239], there is concern that trifluoroacetic acid may accumulate over many years in terminal water bodies to the point that concentrations toxic to algae and some higher plants may be achieved. 

Formaldehyde is highly toxic to algae, protozoan, and other unicellular organisms. Fish show slight toxicity (guppies have TLm = 50-200 mg 1 ). 

Glycerol has low toxicity to algae and fish. The threshold toxicity is reported as greater than 3000mgl- ... 

Dibutyl adipate is readily biodegradable. Although it is considered to be moderately toxic to fish and daphnids and slightly toxic to algae, the environmental risk is considered to be low. Log Pow is 4.17 indicating that there is a moderate to low potential for bioaccumulation. 

Beflubutamid is a newly described carotenoid synthesis inhibitor, inhibiting phytoene desaturase. It has a very low toxicity to animals but is very toxic to algae and plants. It is not mutagenic or teratogenic in standard tests. 

An alternative or complimentary theory for the mode of action of simple phenolic compounds is that they are converted to much more toxic quinones. Pillinger et al. [69] found that various phenolic decomposition products of barley straw were most toxic under conditions favorable for oxidation of the compounds to quinones, and that quinones were up to one thousand-fold more toxic to algae than the parent compounds. The most likely route to conversion to a quinone is enzymatic. Peroxidases and polyphenol oxidases can perform such a reaction, depending on the substrate. However, polyphenol oxidase cannot be detected in most green algae [139] and has not been reported in cyanobacteria. 

The biocidal properties of nickel are modified by many variables. For example, nickel is most lethal at pH 8.3 and least lethal to freshwater crustaceans and fishes at pH 6.3 less toxic to algae when copper is reduced or absent and chelating agents, such as EDTA, are present most lethal to echinoderm embryos prior to gastmlation and more toxic to estuarine amphipods and clams under conditions of decreased salinity in the 0.5-3.5% range and increased temperature in the 5-15°C range. 

Environmental Environmentally hazardous EC50 (daphnia magna, 48 h) 7.4 mg/l, toxic LC50 (fathead minnow, 96 h) 4.2-30 mg/l, harmful to toxic toxic to algae marine pollutant Precaution Combustible vapor and liq. incompat. with strong oxidizing... 

Effects-related parameters toxicity to fish toxicity to Daphnia toxicity to algae toxicity to mammals mutagenicity. 

Table 5.8 Examples of QSAR models for estimating the toxicity to algae of non-specific toxicants log EC50 correlations with various parameters... 

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