U.S. Geological Survey, Fort Collins, Colorado 80523, USA; 2 Texas

Transcription

1 1 2 Linking the Agricultural Landscape of the Midwest to Stream Health with Structural Equation Modeling. 3 4 AUTHORS Travis S. Schmidt 1*, Peter C. Van Metre 2, Daren M. Carlisle tschmidt@usgs.gov, U.S. Geological Survey, Fort Collins, Colorado 80523, USA; 2 Texas Water Science Center, Austin, Texas 78754, USA; 3 U.S. Geological Survey Earth Systems Processes Division, Lawrence, Kansas KEYWORDS multiple stressors, pesticides, algae, invertebrates, fish, streams, land use Number of pages: 15 Number of figures: 2 Number of tables: S1

2 16 Supplemental Information for Publication Figure S1. Portrayed in a meta-model generalizing how landscape structure and landuse change transmit effects through a hierarchical network culminating in alterations to ecological health. Figures 1-4 expand in detail results from the Midwest Steam Quality Assessment. Boxes depict types of variables important to midwestern streams and arrows show the spatial- temporal relationships among variables. Glacial history is indicated by the variable Sand Content in Soil in subsequent models. S2

3 Figure S2. Map of the 100 sites sampled in the Midwestern Stream Quality Assessment (MSQA) in 2013 and corresponding land uses. Two of the 100 streams sampled for water quality were dropped from this analysis: the ecological survey was not done at one stream because of excessive depth (all streams were sampled using wading protocols), and the other stream was considered an outlier on the basis of basin size (>6,000 km 2 ) and its location on the far western edge of the region. Source: S3

4 31 Table S1. Variable definitions and why they were selected to be included in the structural equation models. Note: other variables were also considered for the model, see text for a discussion on why variables were not included in the models. Variable Type of Predicted effects Transformation Why used variable on ecology Land use a Agricultural Land Predictor A study design element to assess the effects of agricultural and urban land uses on stream ecosystems. 4 Indirect (-) NT Urban Land Predictor A study design element to assess the effects of agricultural and urban land uses on stream ecosystems. 4 Indirect (-) NT Natural landscape a Indirect NT Sand Content in Soil Covariate b glacial history, which has been shown to be an important landscape factor in previous assessments of ecological Identified as an important variable in a previous investigation. 11 Also, this quality of soil was correlated with integrity in the Midwest.. 17, 56, 58 Indirect (-) Log (X+1) Basin Area Covariate b Posteriori variable added to scale the influence of other variables that can be influenced by the size of river or stream or the location within the stream network of the sample location. Indirect Log 10 (X) Upland a A metric that determines the proportion of stream sediment comprised of either surface soil from the upland or in Channel Erosion Stressor channel deposits of sediment. This metric has been modified from Gellis et al. 16 in that percent surface derived sediment is subtracted from 1 to describe the proportion of sediment that was derived from the channel Many variables related with riparian condition were identified as important predictors of stream condition. This Direct (+) and Area Stressor predictor was selected to represent riparian factors that could affect water quality and ecological integrity and to mediator of landas Forest simplify the number of predictors considered in the model use effects NT Habitat a Canopy Cover Relative Bed Maximum Temperature Stressor Stressor Many variables related with riparian condition were identified as important predictors of stream condition. This predictor was selected to represent riparian factors that could affect water quality and ecological integrity and to simplify the number of predictors considered in the model Direct (+) Arcsin(sqrt(X/100) d84 and percent fines were used by other investigators. We chose to use Relative Bed as descriptive of both these other predictors to reduce the number of predictors in the model. Related to fish, invertebrates, and Direct (+) X (1/4) algal communities Stressor Found to limit algal communities. 10 Direct (-) NT Synthetic chemicals a Bifenthrin in Sediment Stressor Found to limit invertebrate communities. 21, 22 Direct (-) Log 10 (X+1) Imidacloprid Stressor Detected broadly in the ecoregion at levels thought to cause effects to invertebrate communities. 15 Direct (-) Log 10 (X+1) Pyrethroid Degradates Stressor Found to limit invertebrate communities. 11 Direct (-) Log 10 (X+1) in Water Sum of Triazine Herbicides Stressor Found to limit algal communities. 10 Direct (-) Log 10 (X+1) Nutrients a Ammonia Stressor Found to limit invertebrate communities. 11 Direct (-) Log 10 (X+1) Total Nitrogen Stressor Found to affect fish, invertebrate, and algal communities Total Phosphorus Stressor Found to affect fish and algal communities. 10, 12 dependent direct Log 10 (X) Context effects dependent direct Log 10 (X) Context effects a- Class within which variables are nested for developing total effects. b- Indicates variables not included in the total effects class for which it is listed, rather it is treated as a covariate. NT-Not transformed. S4

5 Table S2. Estimates of regression coefficients (standardized path coefficients) and covariances for the structural equation model of the relationships between stressors in streams of the Midwestern United States. Standardized Standard Response Predictor Z-score p-value 33 R Path Coefficient Error 2 Regressions Agricultural Land Sand Content in Soil Basin Area Urban Land Sand Content in Soil Total Phosphorus Sand Content in Soil Agricultural Land Urban Land Area as Forest Relative Bed Total Nitrogen Agricultural Land Urban Land Relative Bed Ammonia Basin Area Area as Forest Area as Forest Agricultural Land Urban Land Canopy Cover Basin Area Area as Forest Maximum Temperature Sand Content in Soil Basin Area Percent Canopy Relative Bed Urban Land Area as Forest Channel Erosion Channel Erosion Sand Content in Soil Urban Land Sum of Triazine Herbicides Sand Content in Soil Agricultural Land Imidacloprid Sand Content in Soil Agricultural Land Urban Land Pyrethroid Degradates in Water Agricultural Land Urban Land Bifenthrin in Sediment Bifenthrin in Sediment Agricultural Land Urban Land Relative Bed Covariances 1 Agricultural Land Urban Land Total Phosphorus Total Nitrogen Imidacloprid Pyrethroid Degradates in Water Variables with covariances are not response or predictor variables, they are covariates. Fit statistics: Model converged normally after 43 interactions. Robust chi-square = , p-value = 0.328, df = 61, n = 90, Satorra-Bentler correction factor =0.986, Comparative Fit Index = 0.994, Relative Noncentrality Index = 0.994, Robust Root Mean Square Error of Approximation =0.028 (90% confidence interval ( ), Standardized Root Mean Square Residual = 0.070, Incremental Fit Index = S5

6 Table S3. Estimates of regression coefficients (standardized path coefficients), covariances, and latent construct and variables for the structural equation model of the relationships between stressors and algal communities in streams of the Midwestern United States. Response Predictor Standardized Path Standard Coefficient Error Z-score p-value R 2 Regressions Agriculture Land Sand Content in Soil Basin Area Urban Land Sand Content in Soil Total Phosphorus Sand Content in Soil Agriculture Land Urban Land Area as Forest Relative Bed Area as Forest Canopy Cover Maximum Temperature Relative Bed Agriculture Land Urban Land Basin Area Area as Forest Sand Content in Soil Basin Area Canopy Cover Urban Land Area as Forest Channel Erosion Channel Erosion Sand Content in Soil Urban Land Sum of Triazine Herbicides Sand Content in Soil Algae Latent Variable Agriculture Land Total Phosphorus Sum of Triazine Herbicides Maximum Temperature Canopy Cover Covariances 1 Agriculture Land Urban Land Total Phosphorus Sum of Triazine Herbicides Algae Community Health (Latent Variable) 2 Biological Condition Grp Biological Condition Grp Biological Condition Grp Variables with covariances are not response or predictor variables, they are covariates. 2 Latent variables are described by indicator variables which are listed below the named construct above. The latent construct and individual indicators are predicted by the structural equation model; thus, both the construct and the indicators have R 2. 3 Relative Abundance of Biological Condition Gradient Group. The model converged normally after 32 interactions. Robust chi-square = , p-value = 0.330, df = 59, n = 93, Satorra-Bentler correction factor = 1.018, Comparative Fit Index = 0.988, Relative Noncentrality Index = 0.988, Robust Root Mean Square Error of Approximation = (90% confidence interval = ), Standardized Root Mean Square Residual = 0.073, Incremental Fit Index = S6

7 37 Table S4. Estimates of regression coefficients (standardized path coefficients) and covariances for the structural equation model of the relationships between stressors and invertebrate communities in streams of the Midwestern United States. Response Predictor Standardized Path Standard Coefficient Error Z-score p-value R 2 Regressions Agricultural Land Sand Content in Soil Basin Area Urban Land Sand Content in Soil Total Nitrogen Agricultural Land Urban Land Relative Bed Ammonia Basin Area Area as Forest Area Agricultural Land as Forest Urban Land Relative Bed Urban Land Area as Forest Channel Erosion Channel Erosion Sand Content in Soil Urban Land Pyrethroid Degradates Agricultural Land in Water Urban Land Bifenthrin in Sediment Bifenthrin in Sediment Agricultural Land Multi-metric Index of Macroinvertebrate Community Urban Land Relative Bed Area as Forest Total Nitrogen Ammonia Channel Erosion Pyrethroid Degradates in Water Covariances 1 Agricultural Land Urban Land Variables with covariances are not response or predictor variables, they are covariates. The model converged normally after 28 interactions. Robust chi-square = , p-value = 0.566, df = 38, n = 90, Satorra-Bentler correction factor = 0.980, Comparative Fit Index = 1.000, Relative Noncentrality Index = 1.008, Robust Root Mean Square Error of Approximation = (90% confidence interval ( ), Standardized Root Mean Square Residual = 0.052, Incremental Fit Index = S7

8 Table S5. Estimates of regression coefficients (standardized path coefficients) and covariances for the structural equation model of the relationships between stressors and fish communities in streams of the Midwestern United States. Response Predictor Standardized Path Coefficient Standard Error Z-score p-value R 2 Regressions Agricultural Land Sand Content in Soil Basin Area Urban Land Sand Content in Soil Area as Forest Agricultural Land Urban Land Relative Bed Agricultural Land Urban Land Area as Forest Channel Erosion Channel Erosion Sand Content in Soil Multi-metric Index of Fish Community Urban Land Sand Content in Soil Relative Bed Area as Forest Covariances Agricultural Land Urban Land Variables with covariances are not response or predictor variables, they are covariates. The model converged normally after 30 interactions. Robust chi-square = 6.615, p-value = 0.882, df = 12, n = 91, Satorra-Bentler correction factor = 0.950, Comparative Fit Index = 1.000, Relative Noncentrality Index = 1.023, Robust Root Mean Square Error of Approximation = (90% confidence interval ( ), Standardized Root Mean Square Residual = 0.036, Incremental Fit Index = S8

9 Table S6. Direct, indirect, and total effects (standardized path coefficients) of each predictor of algal, invertebrate, or fish communities observed in streams of the Midwestern United States. Response variables Predictor Macroinvertebrate Multimetric Algae Latent Variable Variable Fish Multi-metric Direct Indirect Total Direct Indirect Total Direct Indirect Total Agricultural Land Urban Land Sand Content in Soil Basin Area Area as Forest Channel Erosion Relative Bed Canopy Cover Maximum Temperature Total Phosphorus Sum of Triazine Herbicides Total Nitrogen Ammonia Pyrethroid Degradates in Water Bifenthrin in Sediment

10 Table S7. Covariance matrix and means used to estimate the structural equation model relations among variables of stream condition in the Midwestern United States. Ag Land Urb Land Total P Ag Land Urb Land Total P Total N NH 4 % Rip. as Forest % Canopy Temp. RBS Erosion Herbicides Imidacloprid Pyrethroid Degradates Bifenthrin Sand Content Basin Area Total N NH % Rip. as Forest % Canopy Temp RBS Erosion Herbicides Imidacloprid Pyrethroid Degradates Bifenthrin Sand Content Basin Area Means Ag Land =Agricultural Land, Urb Land =Urban Land, Total P=Total Phosphorous, Total N=Total Nitrogen, NH4=Ammonia, % Rip. as Forest= Area as Forest, % Canopy=Percent Riparian Canopy Cover, Temp.=Maximum Temperature, RBS=Relative Bed, Erosion=Channel Erosion, Herbicides=Sum of Triazine Herbicides, Pyrethroid Degradates=Pyrethroid Degradates in water, Bifenthrin=Bifenthrin in Sediment, Sand Content=Sand Content in Soil

11 Table S8. Covariance matrix and means used to estimate the structural equation model of stressor effects to algal communities in streams of the Midwestern United States. BCG Grp 2 BCG Grp BCG Grp 3 BCG Grp BCG Grp 4 BCG Grp Agriculture Land Urban Land Total Phosphorus Riparian Forest Area Percent Riparian Canopy Agriculture Land Urban Land Total Phosphorus Riparian Forest Area Percent Riparian Canopy Maximum Temperature Relative Bed Channel Erosion Sum of Triazine Herbicides Sand Content Basin Area Maximum Temperature Relative Bed Channel Erosion Sum of Triazine Herbicides Sand Content Basin Area Means BCG Grp= Relative Abundance of algae in a Biological Condition Gradient Group, Riparian Forest Area= Area as Forest, Canopy= Canopy Cover, Sand Content=Sand Content in Soil

12 Table S9. Covariance matrix and means used to estimate the structural equation model of stressor effects to invertebrate communities in streams of the Midwestern United States. Agricultural Land Urban Land Total Nitrogen Ammonia % Rip. as Forest RBS Channel Erosion Pyrethroid Degradates in Water Bifenthrin in Sediment Macroinvertebrate Multi-metric Sand Content in Soil Basin Area Agricultural Land Urban Land Total Nitrogen Ammonia Area as Forest Relative Bed Channel Erosions Pyrethroid Degradates in Water Bifenthrin in Sediment Macroinvertebrate Multi-metric Sand Content in Soil Basin Area Means % Rip. As Forest= Area as Forest, RBS=Relative Bed 44 12

13 45 Table S10. Covariance matrix and means used to estimate the structural equation model of stressor effects to fish communities in streams of the Midwestern United States. Agricultural Land Urban Land Percent Riparian Area as Forest Agricultural Land Urban Land Area as Forest Relative Bed Channel Erosion Multi-metric Index of Fish Community Sand Content in Soil Relative Bed Channel Erosion Multi-metric Index of Fish Community Sand Content in Soil Basin Area Means Basin Area 13

14 Table S11. Median variable values for sites classified on glacial history. Variable Pre-Wisconsin Late-Wisconsin Channel Erosion Surface Erosion Canopy Cover Imidacloprid Sum of Triazine Herbicides Pyrethroid Degredates Bifenthrin in Sediment Maximum Temperature Total Phosphorus Total Nitrogen Ammonia Relative Bed MMI_FISH MMI_INSECTS BC_2.RelAbun BC_3.RelAbun BC_4.RelAbun Urban Land Agriculture Land Sand Content in Soil Area as Forest Basin Area Base Flow Index Basin Slope Row Crops BC= Biological Condition Group, RelAbun=Relative abundance. 14

15 Table S12. Summary statistics based on raw data values of each variable used in the structural equation modeling. Variable Median Range Channel Erosion (%) Surface Erosion (%) Canopy Cover (%) Imidacloprid (ng/pocis) Sum of Triazine Herbicides (ng/l) Pyrethroid Degredates (ng/pocis) Bifenthrin in Sediment (% of likely effects benchmark) Maximum Temperature ( C) Total Phosphorus (mg/l) Total Nitrogen (mg/l) Ammonia (mg/l) Relative Bed MMI_FISH (score) MMI_INSECTS (score) BC_2.RelAbun (%) BC_3.RelAbun (%) BC_4.RelAbun (%) Urban land use (%) Agriculture land use (%) Sand Content in Soil (%) Riparian Area as Forest (%) Basin Area (km 2 ) Base Flow Index (% of base flow to total streamflow) Basin Slope (%) Row Crops (%) See more details in Moran et al. (2011) 21 and Nowell et al. (2018) 13. MMI=Multimetric Index, BC=Biological Condition Group, RelAbund=Relative abundance. 15