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2D - Mechanisms of toxic action (MOP/92) Threats to freshwater ecosystems from glyphosate-based herbicide applications on land. PECHLANER, Roland1, PFISTER, Peter 2, PIPP, Eveline1, ROTT, Eugen1, 1 University of Innsbruck, Innsbruck, TIROL, AUSTRIA2 ARGE Limnologie - Angewandte Gewässerökologie GesmbH, Innsbruck, TIROL, AUSTRIA ABSTRACT- Macrophytes and periphyton algae in rivers and lakes as well as the majority of heterotrophic microorganisms plus animal food chains relying on bacterial or fungal production processes in both surface and ground waters must suffer from "collateral damage" due to glyphosate use on land. The book "Glyphosate: A Unique Global Herbicide"by Franz et al.(1997;ACS Monograph 189:1-653) is offering many mosaic stones to compose a detailed picture concerning non-target effects of weed control with this particular herbicide. The paper concentrates on obvious (but not yet adequately assessed) risks resulting from glyphosate use for macrophytes, algae and most functional types of microorganisms in many aquatic habitats where a specific complex of microbial diversity and functioning is essential for sustainability. This presentation provides information for achieving 3 goals: (1) To falsify the frequently reported opinion that biological degradability of glyphosate is well documented and generally high, and that environmental impact has been shown by adequate risk-assessment to be low.(2) To understand interrelations between abiotic conditions and the structure and functioning of the biota of aquatic habitats, where glyphosate molecules originating from terrestrial applications may be neither adequately diluted nor present in a biologically inert form as to justify the acceptance of further invasions by spray, inflow or on clay minerals or organic particles transported by runoff or wind. (3) To indicate serious disadvantages for successful work in response to the EU Water Framework Directive, if "silent killing" of important water quality indicator species as a consequence of inadequate control of glyphosate applications is neither understood nor reduced. All four authors of this paper are limnologists rather than ecotoxicologists. It is their fourth goal to adress specialists within and outside SETAC for accepting their responsibility after decades of blindness and obscuration concerning glyphosatogenic impacts on aquatic systems, on microbial life in soils and on animal nutrition, wherever digestion of plant material depends on enzymes of microbial symbionts. Key words: non-target effects on microorganisms, glyphosate-based herbicides, freshwater algae and macrophytes, remobilization of herbicides |
