Investigations of the effects of two triazine herbicides on periphytic algal communities in the Delta Marsh, Manitoba

Abstract

Triazine herbicides are used in aquatic management primarily to control macrophytes and undesirable phytoplankton populations. Triazines used for terrestrial weed control also enter aquatic systems through runoff, aerial drift or from spillage. This study assesses the impact of two of these triazines, simazine and terbutryn, on the structure, function and biomass of periphytic algae within in-situ littoral enclosures. Secondary effects of treatment on water chemistry were also monitored during an 87 days experimental period. The second half of this study describes an automated quantitative grain density microautoradiography procedure. The effects of Lugol's iodine on isotope leakage from cells preserved for autoradiography, was demonstrated using three haptobenthic diatom species. The applicability of using this technique to evaluate intra and interspecific variation in algal response to triazine exposure in-situ was also discussed.