title: Effects of a herbicide mixture on primary and bacterial productivity in four prairie wetlands with varying salinities: an enclosure approach.
abstract: Wetlands in the Prairie pothole region of Saskatchewan and Manitoba serve an important role in providing wildlife habitat, water storage and water filtration. They display a wide range of water quality parameters such as salinity, nutrients and major ions with sulfate as the dominant ion for the most saline wetlands. The differences in these water quality parameters among wetlands are reflected in the composition of aquatic plant communities and their productivity. Interspersed within an intensely managed agricultural landscape where pesticides are commonly used, mixtures of herbicides are often detected in these wetlands as well as in rivers, and drinking water reservoirs. One freshwater and three wetlands of varying salinity in the St. Denis National Wildlife Area, Saskatchewan, Canada were selected to study the effects of a mixture of eight herbicides (2,4-D, MCPA, dicamba, clopyralid, bromoxynil, mecoprop, dichlorprop, and glyphosate) on wetland microbial communities using an outdoor enclosure approach. Six enclosures (three controls and three treatments) were installed in each wetland and the herbicide mixture added to the treatment enclosures. The concentration of each herbicide in the enclosure water was that which would have resulted from a direct overspray of a 0.5-m deep wetland at its recommended field application rate. After herbicide addition, primary and bacterial productivity, and algal biomass were measured in both planktonic and benthic communities over 28 days. The herbicide mixture had a stimulatory effect on primary productivity in the nutrient-sufficient freshwater wetland while no stimulatory effect was observed in the nutrient-deficient saline wetlands. The differences observed in the effects of the herbicide mixture appear to be related to the nutrient bioavailability in these wetlands.
authors: Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5A8, Canada. Electronic address: srinivas.sura@ec.gc.ca.
authors: Srinivas
authors: S
authors: Sura
authors: Environment Canada, Saskatoon, Saskatchewan S7N 3H5, Canada. Electronic address: Mjwaiser@shaw.ca.
authors: Marley J
authors: MJ
authors: Waiser
authors: Environment Canada, Saskatoon, Saskatchewan S7N 3H5, Canada. Electronic address: Vijay.tumber@eg.gc.ca.
authors: Vijay
authors: V
authors: Tumber
authors: Department of Chemistry and Biochemistry, and Trace Analysis Facility, University of Regina, Regina, Saskatchewan S4S 0A2, Canada. Electronic address: Renata.raina@uregina.ca.
authors: Renata
authors: R
authors: Raina-Fulton
authors: Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan S7N 0X2, Canada. Electronic address: Allan.cessna@ec.gc.ca.
authors: Allan J
authors: AJ
authors: Cessna
mesh_terms: D004784:Environmental Monitoring; D065948:Grassland; D006540:Herbicides / Q000633:toxicity*; D008350:Manitoba; D054712:Salinity; D012525:Saskatchewan; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D053833:Wetlands
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical
keywords: Herbicide mixtures; Microbial communities; Primary productivity; Salinity; Wetlands