US EPA

2199665 

Technical Report 

Impact of pesticides on phytoplankton in Everglades estuaries 

Moore SA Jr 

1973 

PESTAB/76/0398 

Tech 

PESTAB. Six and 24-hour bioassays were conducted to determine in situ the effect of selected organochlorine compounds on natural communities of estuarine phytoplankton. The effect of organochlorine concentration observed was to reduce phytoplankton utilization of bicarbonate thereby also reducing photosynthetic production of organic material. Polychlorinated biphenyls (PCBs: Aroclor 1242 and Aroclor 1245) phytotoxicity occurred at PCB levels less than 5 mug PCB/1. P,P'-DDT phytotoxicity initiated at concentrations of 10 mug DDT/1. Phytotoxicity by dieldrin is inconclusive. No phytotoxicity was observed in one ecosystem. A typical dose-response toxicity was observed in a second ecosystem and indicated apparent dieldrin toxicity at 15 mug dieldrin/1. Nannoplankton and netplankton difference in Aroclor 1242 sensitivity was observed. 10 mug/l and 25 mug/l PCB did not inhibit nannoplankton which contributed approximately 73% of the phytoplankton production. Netplankton production was inhibited by more than 50% in both the 10 mug/l and 25 mug/l PCB concentrations. (Author abstract by permission)