, 2012a, Brodie and Waterhouse, 2012 and Lewis et al., 2009). Satellite imagery effectively captures these events and their associated flood plumes migrating up to 50 km offshore as far as the midshelf coral reefs (Bainbridge et al., 2012). A wide spectrum of pesticides this website have been detected in waters of the GBR, but herbicides are often more water soluble and mobile than contemporary insecticides and fungicides, and as a consequence, are more frequently detected in the river mouths and GBR lagoon (Brodie et al., 2012b, Davis et al., 2011 and Lewis et al., 2009). The photosystem II herbicides have
been the primary group detected in GBR waters; however, glyphosate (CAS number 1071-83-6) is the most widely used herbicide in Australia, in the GBR catchments and elsewhere, with approximately 15,000 tonnes applied annually to control agricultural, urban and roadside weeds (Beeton et al., 2006 and Radcliffe, 2002). The popularity of glyphosate has increased steadily since its introduction in the mid 1970s as it exhibits: (i) relatively low toxicity to non-target organisms (Borggaard and Gimsing, 2008 and Duke and Powles, 2008); (ii) apparent rapid microbial
degradation to a major metabolite aminophosphonic selleck kinase inhibitor acid (AMPA) (Giesy et al., 2000) and (iii) strong adsorption to soils and sediments potentially limiting runoff in surface water (Duke and Powles, 2008, Pérez et al., 2012 and Solomon and Thompson, 2003). Glyphosate has not often been included in regular monitoring programs as the stand-alone analytical methods are often cost-prohibitive, resulting in a long term deficiency in global datasets (Barceló and Hennion, 2003). However, glyphosate has been regularly detected in a diversity of waterbodies when samples were analysed (see Table 1). For example, glyphosate and AMPA were detected in 36% and 69% of water samples respectively, following extensive sampling of aquatic ecosystems
in the Midwestern United States (Battaglin et al., 2005 and Scribner et al., 2003). Concentrations measured in field studies in Australia have Cyclin-dependent kinase 3 been reported as high as 54 μg L−1 (Davis et al., 2011). A similar concentration (40.8 μg L−1) was measured in Canada (Struger et al., 2008), while field dissipation studies found concentrations as high as 1700 μg L−1 (Mensink and Janssen, 1994 and NHMRC, 2011). Glyphosate exhibits a relatively low toxicity to non-target marine organisms, with the LC50s of glyphosate (lethal concentration which affects half of the sample population) in the 10–1000 mg L−1 range. However, recent research suggests that low μg L−1 concentrations can affect natural coastal microbial communities (Stachowski-Haberkorn et al., 2008).