Acute impact of an organophosphorus insecticide on microbes and small invertebrates of a mangrove estuary.

The effects of 24 to 72-hr exposure to fenthion (10(1)-10(3) ppb) were determined for a fungal community, nitrogen-fixing microbes, and representative meiofaunal and zooplankton invertebrates of a mangrove ecosystem. Also tested were the abilities of a benthic diatom and of fungi to grow in the presence of fenthion. Acute lethal, growth-inhibiting, or process-disrupting effects were not detected for exposures to less than 500 ppb fenthion. Results are compared with the findings of several other investigations of the impact of fenthion and other organophosphorus insecticides on non-target organisms.