MUGNI Hernan Diego
capítulos de libros
Integrated approach for the assessment of biotech soybean pesticides impact on low order stream ecosystems of the Pampasic region.
Ecosystem Ecology Research Trends.
Nova Science Publishers.
Lugar: Hauppauge, NY 11788; Año: 2008; p. 209 - 239
Abstract In the last decade Argentine farmers have massively adopted the genetically modified glyphosate resistant soybean together with no tillage managerial practices. The area cultured with soybeans increased to 15 million ha with consequent higher pesticide consumption. Although recent publications deal with some detailed aspects of pesticide effects on organisms, the overall impact of such vast agricultural intensification remains unreported. The present contribution review and integrate results from laboratory and field studies within the frame of a major project oriented towards an integrated assessment of soybean agrochemicals impacts on aquatic ecosystems from low order streams of the region. Main conclusions of the different studies are: i) chemical analysis of water, sediments and soils indicate low impacts on nutrient levels; ii) all the biota components of the studied ecosystems (flora, insects, fish and amphibians) were affected in different extent after pesticide applications, representing an appreciable stress over the systems. Effects were sometimes low, without noticeable impact on resident populations, as observed in fishes, or being more drastic, populations tend to recover after the episodic toxicity pulses, as observed in the resident invertebrate fauna; iii) of the three most commonly used insecticides, endosulphan fumigation caused the most severe effects, followed by the terrestrial chlorpyriphos and cypermethrin applications; iv) regarding spatial extent of impacts, the herbicide glyphosate drift and runoff caused chlorophyll content reduction on adjacent riparian and, at least 250 meters downstream application, on aquatic macrophyte vegetation. Although effects were followed by later recovery, studied sites showed a rather poor ruderal composition, suggesting that reiterated applications, together with the history of land use eventually impoverished the regional community originally described for the area. The populations of non target invertebrates were the most sensitive ecosystem components, showing the strongest effects, with total disappearance of some groups of the resident fauna (ephemeroptera, odonata, amphipoda) as a response to pesticide runoff, eventually at long distance from spray areas, while fish and amphibian impacts were generally circumscribed to adjacent sectors, possibly reaching the water body from pesticide drifts of applications; v) in situ exposed experimental populations of insects, fish and amphibians showed good correspondence with observed responses of resident populations assessed within the same watercourses. The selection of the sites of study and the combined battery of sampling methods were of great significance for allowing the detection of effects with different degree of ecological significance; vi) finally, complementation between laboratory and field studies resulted of great significance for detecting erroneous predictions from the former and lighten observations from the latter. An integrated approach analysis seems to be a promising option towards the understanding of the overall impact of intense soybean farming on aquatic related environments. Improving managerial practices and riparian habitat restorations seems feasible goals for long term sustainable production.