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Especially for early incoming data (Version 1.0 and 2.0) records typically came to us lacking latitude and longitude, and even when present they were unreliable. In order to assure consistent high quality of spatial placement of records, we manually assigned latitude and longitude coordinates and error estimates to collection localities. Since that an initial effort on our data tracks 1 and 2, it has become common place commonplace for collections to include coordinates in their databases and their quality has greatly improved. Collectors now routinely submit coordinates with specimens since GPS has become ubiquitous and many collections have georeferenced their own older collection records as well. Newer data imported as part of our Version 3.0 of the project often included what we determined to be accurate coordinates and often with spatial error, indicated as a radius from the set of coordinates. Due to this change, we’ve accepted, at least on a preliminary basis, many more georeferences provided by donors. Thus, at the time we released Version 3 of the database and website, our data includes a combination of records georeferenced manually by our team and those that have come from donor sources directly.
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- Georeferences received with new records were preliminarily accepted. Our intent is to review the donor georeferences and edit as needed.
- Many records that were previously not georeferenced have now been georeferenced at their donor institutions and we were able to extract those coordinates and apply them to those records. This especially effects those records that are in our neighbor states and in shared basins.
- Many of our oldest records in tracks 1 and 2 were collected during Texas boundary and rail road surveys in the early to mid-1800's and lacked specific locality details (no/little text and no coordinates). In version 3 of the database we updated most of the oldest records by reviewing the original survey reports and maps to extrapolate their locations. Delving into the literature also also allowed us to improve collection dates and collector names.
- Since many of the newer records in track 3 lacked spatial error, and our spatial algorithms require our georeferences to have a spatial errorit, we usually applied a default error radius of 45 meters or used the number of digits provided after the decimal to derive an error.
- When we could unambiguously match a textual locality description to that of a previously georeferenced location, we copied its georeference data to the ungeoreferenced locality.
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- Georeferences include coordinates (latitude and longitude) in decimal degrees (WGS84 datum) and an error radius (or spatial extent) measured in meters that together define a circle. All All serious users should understand that the true location of the occurrence may occur anywhere within the circle.
- We edited locality descriptions to correct and normalize spelling (using standard place names), and improved syntax of locality descriptions.
- Our notes indicate why locations could not be georeferenced and describe any decisions made about coordinates and error.
- Generally, georeferences were determined without consideration of taxa in order to ensure biases did not come into play. However, some georeferences were adjusted later based on distributional or habitat information when consensus could be made between at least two staff.
- Once the data were georeferenced, we were able to use a Geographic Information System to populate our database with categorical variables such as county, river drainage, USGS hydrologic unit codes, and more. Records that could not, or were not georeferenced, lack this step. These data were extracted from the coordinates, regardless of error, so it is possible for categorical variables to be incorrectly assigned. Since our query interface allows for querying among these categorical spatial parameters there can be some confusion. For example, a location with coordinates in county A and an error that extends into county B will only be pulled when county A is designated in the query. Even though the overlapping georeferenced error estimate means that this occurrence could likely occur in county B, it cannot be found by querying for county B.
- Some records could not be georeferenced. This usually happens when there is an internal conflict in a locality description or a named place cannot be found.
- Fish obviously are limited to water, but not all coordinates in our database fall on water features. Users should remember that some locality descriptions are vague and do not allow precise placement of points.
- Georeferences are continually refined based on new information and comments from FoTX users are important for improving our georeferences.
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