Amphibians environment

Oberemm A, Becker J, Codd GA, Steinberg C (1999) Effects of cyanobacterial toxins and aqueous crude extracts of cyanobacteria on the development of fish and amphibians. Environ Toxicol 14 77-88... 

Bridges, C.M. Little, E.E. Gardiner, D.M. Petty, J.D. Huckins, J.N. 2004, Assessing the toxicity of teratogenicity of pond water in North-Central Minnesota to amphibians. Environ. Set Pollut. R. 11 233-239. 

A. Zaga, E.A. Little, C.F. Rabeni, M.R. Ellersieck (1998). Photoenhanced toxicity of a carbamate insecticide to early life stage anuran amphibians. Environ. Toxicol. Chem., 17, 2543-2553. 

Berrill, M., D. Coulson, L. McGillivray, and B. Pauli. 1998. Toxicity of endosulfan to aquatic stages of anuran amphibians. Environ. Toxicol. Chem. 17 1738-1744. 

Allran, J. Karasov, W. (2001) Effects of atrazine on embryos, larvae and adults of anuran amphibians. Environ. Toxicol. Chem. V. 20, Nq. 4, pp. 769-775. 

More controversially, endocrine disruption as a consequence of exposure to the herbicide atrazine (2-chloro-4-ethylamine-6-isopropylamine-s-triazine), one of the most widely used herbicides in the world, has also been hypothesized to explain various adverse biological effects in frog populations in the United States. Exposure to atrazine in the laboratory at high concentrations, far exceeding those found in the natural environment, has been reported to induce external deformities in the anuran species Rana pipiens, Rana sylvatica, and Bufo americanus (Allran and Karasov 2001). Studies by Hayes et al. have suggested that atrazine can induce hermaphroditism in amphibians at environmentally relevant concentrations (Hayes et al. 2002 Hayes et al. 2003). Laboratory studies with atrazine also indicated the herbicide... 

Gutleb, A.C., Appehnan, J., and Bronkhorst, M. et al. (2000). Effects of oral exposure to polychlorinated biphenyls (PCBs) on the development and metamorphosis of two amphibian species (Xenopus laevis and Rana temporaria). Science of the Total Environment 262, 147-157. 

Davis KR, Schultz TW, Dumont JN (1981) Toxic and teratogenic effects of selected aromatic amines on embryos of the amphibian Xenopus laevis. Arch Environ Contamin... 

Unsaturations of lipids play a key role in lipid homeostasis, where organisms adapt to temperature variations of the environment. Plants and animals maintain physiological functions by reversibly altering the composition and conformation of lipid molecules of the cell membrane. To achieve this, they extensively and elegantly use the unsaturations (double bonds) present in their side chains. This is the process by which cell membranes adjust their flexibility (fluidity) of the bilayer and adapt themselves to perturbations in temperature, pressure, and other variations in the natural environment [11-14]. They remain indispensable for the poikilothermism exhibited by fishes, invertebrates, and amphibians [15, 16]. Commercially,... 

Herkovits, J. and C.S. Perez-Coll. 1991. Antagonism and synergism between lead and zinc in amphibian larvae. Environ. Pollut. 69 217-221. 

Birge, W.J., J.A. Black, A.G. Westerman, and J.E. Hudson. 1979. The effect of mercury on reproduction of fish and amphibians. Pages 629-655 in J. 0. Nriagu (ed.). The Biogeochemistry of Mercury in the Environment. Elsevier/North-Holland Biomedical Press, NY. 

Howe, G.E., R. Gillis, and R.C. Mowbray. 1998. Effect of chemical synergy and larval stage on the toxicity of atrazine and alachlor to amphibian larvae. Environ. Toxicol. Chem. 17 519-525. 

Synthetic pyrethroids now account for at least 30% of the world insecticide market and are rapidly replacing other agricultural chemicals for control of insect pests. Fenvalerate is one of the more widely used synthetic pyrethroid insecticides. It is derived from a combination of a-cyano-3-phenoxybenzyl alcohol and a-isopropyl phenylacetate ester. Technical fenvalerate is a mixture of four optical isomers, each occurring in equal amounts but with different efficacies against insect pests. Fenvalerate does not usually persist in the environment for >10 weeks, and it does not accumulate readily in the biosphere. Time for 50% loss (Tb 1/2) in fenvalerate-exposed amphibians, birds, and mammals was 6 to 14 h for reptiles, terrestrial insects, aquatic snails, and fish it was >14 h to <2 days and for various species of crop plants, it was 2 to 28 days. Fenvalerate degradation in water is due primarily to photoactivity, and in soils to microbial activity. Half-time persistence in nonbiological materials is variable, but may range up to 6 days in freshwater, 34 days in seawater, 6 weeks in estuarine sediments, and 9 weeks in soils. 

Fenvalerate persists for <10 weeks in the environment and does not accumulate readily in the biosphere. Time for 50% loss (Tb 1/2) in fenvalerate-exposed amphibians, birds, and mammals is 6 to 14 h. For reptiles, terrestrial insects, aquatic snails, and fish, it is usually >14 h to <2 days and for crop plants, it is 2 to 28 days. In nonbiological compartments, Tb 1/2 is up to 6 days in freshwater, 34 days in seawater, 6 weeks in estuarine sediments, and 9 weeks in soils. 

Hatch, A.C. and G.A. Burton, Jr. 1998. Effects of photoinduced toxicity of fluoranthene on amphibian embryos and larvae. Environ. Toxicol. Chem. 17 1777-1785. 

Greulich, K., Hoque, E., and Pflugmacher, S., Uptake, metabolism, and effects on detoxication enzymes of isoproturon in spawn and tadpoles of amphibians, Ecotoxicol. Environ. Saf., 52, 256, 2002. 

Rollins-Smith, L.A., Hopkins, B.D., and Reinert, L.K. An amphibian model to test the effects of xenobiotic chemicals on development of the hematopoietic system, Environ. Toxicol. Chem., 23, 2863, 2004. 

Crump, M. L. (1983) Opportunistic cannibalism by amphibian larvae in temporary aquatic environments. Am. Nat. 121, 281-289. 

Tavera-Mendoza L, Ruby S, Brousseau P, Fournier M, Cyr D, Marcogliese, D (2002a) Response of the amphibian tadpole (Xenopus laevis) to atrazine during sexual differentiation of the testis. Environ Toxicol Chem 21 527-531... 

Laposata, M.M. and W.A. Dunson. 1998. Effects of boron and nitrate on hatching success of amphibian eggs. Arch. Environ. Contam. Toxicol. 35 615-619. 

Ammonia is not hazardous to humans and other mammals because the existence of a specific mechanism in their bodies leads to the conversion and excretion of ammonia. However, fish and amphibians lack this mechanism, and as a result ammonia is very toxic and dangerous to the aquatic environment. 

Ammonia is also the major nitrogenous end product in some of the simpler aquatic and marine animal forms, such as protozoa, nematodes, and even bony fishes, aquatic amphibia, and amphibian larvae. Such animals are called am-monotelic. But in many animals, NH3 is toxic, and its removal by simple diffusion is difficult. Thus, in terrestrial snails and amphibia, as well as in other animals living in environments in which water is limited, urea is the principal end product (fig. 22.6). Urea formation also helps to maintain osmotic balance with seawater in cartilagenous fishes. In such animals, most of the urea secreted by the kidney glomerulus is reabsorbed by the tubules. Indeed, the amount of nitrogen excreted by the kidneys of fishes is small com-... 

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