Toxicity of methyltins to microbial populations in estuarine sediments

The toxicities of three organotin compounds were examined on natural populations of microorganisms in sediments from Boston Harbor. Mono-, di-and trimethyltins were toxic to organisms from these sediments, and the di-and trimethyl compounds were more toxic than the monomethyl compound as measured by either viable counts or by [3H]thymidine uptake. Approximately three to eight times as much organotin was required to achieve the same effect measured by thymidine uptake as measured by viable counts. The results of replica plating experiments suggest that most estuarine organisms which are resistant to one methyltin will be resistant to other methyltins. LC-values suggest that at concentrations reported for methyltins in aquatic environments, methyltins alone are not likely to cause major alterations in the microbial flora. However, these compounds may combine with other stressors to alter the composition of natural populations.