Figure 1.
Location of study areas relative to areas of intensive corn production.
NS = the Neal Smith National Wildlife Refuge; UMR = the Upper Mississippi River National Wildlife and Fish Refuge; SCNSR = the St. Croix National Scenic Riverway; VNP = Voyageurs National Park. Gray tones across counties indicate total number of ha planted in corn in 2007 [41], rendered via classes representing natural breaks in the data distribution.
Figure 2.
Percent of the surrounding landscape planted in corn within successive buffers outwards from each study area during 2008.
NS = the Neal Smith National Wildlife Refuge; UMR = the Upper Mississippi River National Wildlife and Fish Refuge; SCNSR = the St. Croix National Scenic Riverway; VNP = Voyageurs National Park.
Table 1.
Naïve estimates (number of sites where we observed each species relative to the total number of sites we surveyed) from daytime surveys conducted during 2002 to 2005.
Table 2.
Naïve estimates (number of sites where we observed each species relative to the total number of sites we surveyed) from nighttime call surveys during 2002 to 2005.
Table 3.
Estimated values for parameters from site occupancy models of data collected via daytime surveys in the Neal Smith National Wildlife Refuge from 2004 to 2005.
Table 4.
Estimated values for parameters from site occupancy models of data collected via daytime surveys in the Upper Mississippi River National Wildlife and Fish Refuge from 2002 to 2005.
Table 5.
Estimated values for parameters from site occupancy models of data collected via daytime surveys in the St. Croix National Scenic Riverway from 2002 to 2005.
Table 6.
Estimated values for parameters from site occupancy models of data collected via daytime surveys in Voyageurs National Park from 2002 to 2005.
Figure 3.
Median triazine concentrations and the percent of male Lithobates pipiens metamorphs with echinostome infections at individual breeding sites.
Sites identified with a V, SC, or P were in Voyageurs National Park, the St. Croix National Scenic Riverway, and the Upper Mississippi River National Wildlife and Fish Refuge, respectively. Triazine concentrations at sites with no vertical bars were below the detection limit (0.050 ppb) of the enzyme-linked immunosorbent assay used to analyze water samples.
Figure 4.
Median triazine concentrations, the percent of male Lithobates pipiens metamorphs with echinostome infections, and the mean maximum number of echinostomes measured per metamorph kidney section.
Sites identified with a V, SC, or P were in Voyageurs National Park, the St. Croix National Scenic Riverway, and the Upper Mississippi River National Wildlife and Fish Refuge, respectively. Triazine concentrations at sites with no vertical bars were below the detection limit (0.050 ppb) of the enzyme-linked immunosorbent assay used to analyze water samples.
Figure 5.
Triazine concentrations measured in water samples from amphibian breeding sites across study areas via an enzyme-linked immunosorbent assay.
NS = the Neal Smith National Wildlife Refuge; UMR = the Upper Mississippi River National Wildlife and Fish Refuge; SCNSR = the St. Croix National Scenic Riverway; VNP = Voyageurs National Park. Values do not include samples from the main channel of the Mississippi River in the UMR. Horizontal lines within boxes indicate median values. The middle 50% of the data are contained within each box. Vertical lines attached to tops and bottoms of boxes extend to the highest and lowest values. Reference line at 0.05 ppb = the detection limit of the assay.
Figure 6.
Triazine concentrations measured in water samples collected from amphibian breeding sites and sites in the main channel of the Mississippi River in the Upper Mississippi River National Wildlife and Fish Refuge via an enzyme-linked immunosorbent assay.
Symbols represent individual sites sampled. Symbols used for individual sites are consistent across graphs. Solid line near the top of each graph is the hydrograph of the Mississippi River (http://www2.mvr.usace.army.mil/WaterControl/new/layout.cfm) averaged across pools in which we sampled.