Service Description: This map shows directional trends and the central tendency in zebra mussel sightings for each year.
Service ItemId: 535f6d601da94c94a46cad140c8fe730
Has Versioned Data: false
Max Record Count: 5000
Supported query Formats: JSON
Supports applyEdits with GlobalIds: False
Supports Shared Templates: False
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Description: Standard deviation ellipses allow you to see if the distribution of features is elongated and has a particular orientation. The ovals on this map indicate that there’s a directional trend, primarily toward the northeast and southwest, which was stronger in the earlier years. The ellipses for earlier time periods are smaller; for later time periods, larger ellipses were generated. This indicates that the spatial extent of zebra mussels is growing over time (i.e., their range is increasing).
The central tendency is useful for tracking changes in the distribution from year to year. The shift in the mean center indicates that the zebra mussels are spreading toward the southwest after having been primarily concentrated in the Great Lakes region for over a decade.
Copyright Text: Esri, USGS, U.S. National Atlas
Spatial Reference: 102100 (3857)
Initial Extent:
XMin: -16409409.3218897
YMin: 2708422.16919674
XMax: -5256270.69859609
YMax: 6967164.02001378
Spatial Reference: 102100 (3857)
Full Extent:
XMin: -13519466.0657517
YMin: 3407917.54115347
XMax: -7658338.8302002
YMax: 6182467.59324615
Spatial Reference: 102100 (3857)
Units: esriMeters
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