The toxic cyanobacteria that clog ponds with thick, green muck may cause deformities in frogs, according to Czech scientists. Since the 1970s, more and more frogs around the world have been born with missing legs or deformed eyes. Scientists have suspected that the deformities may come from the frogs’ exposure as tadpoles to retinoic acids, a class of chemicals produced by toxic water bacteria. Using samples from Europe and the United States, the Czech scientists have identified three common types of cyanobacteria that secrete retinoic acids into water. Disturbingly, the scientists found that these bacteria-made retinoic acids caused laboratory fish to develop birth defects similar to those increasingly experienced by frogs in the natural environment.
Jonas A, Buranova V, Scholz S, Fetter E, Novakova K, Kohoutek J, & Hilscherova K (2014). Retinoid-like activity and teratogenic effects of cyanobacterial exudates. Aquatic toxicology (Amsterdam, Netherlands), 155, 283-90 PMID: 25103898