| Supplemental information |
This data was revised on 09-29-09. The revisions resulted in the removal of polygon overlap which increased overall kelp area 1.40 sq. mi. The overlap involved the following administrative beds: (a) South coast bed 2 (0.068464 sq. mi.), bed 3 (1.308990 sq. mi.), bed 6 ( 0.002546 sq. mi.), bed 8 (0.001297 sq. mi.), bed 19 ( 0.000346 sq. mi.), bed 103 (0.000135 sq. mi.), bed 104 (0.000002 sq. mi.), bed 105 (0.000185 sq. mi.), bed 106 (0.000123 sq. mi.), bed 107 (0.001479 sq. mi.), bed 108 (0.000099 sq. mi.), bed 109 (0.000004 sq. mi.), bed 110 (0.001054 sq. mi.), bed 113 (0.000315 sq. mi.), bed 114 (0.000010 sq. mi.), bed 115 ( 0.004250 sq. mi.), bed 116 (0.000002 sq. mi.), bed 117 (0.000016 sq. mi.), bed 118 ( 0.000410 sq. mi.) (b) Central coast bed 34 (0.000005 sq. mi.), bed 204 (0.001309 sq. mi.), bed 205 (0.000034 sq. mi.), bed 207 (0.000711 sq. mi.), bed 209 (0.000086 sq. mi.), bed 212 (0.000008 sq. mi.), bed 214 ( 0.000023 sq. mi.) (c) North central coast bed 303 (0.000739 sq. mi.) and bed 304 (0.002404 sq. mi.) In addition, the data was intersected with the administrative kelp beds Dennis Bedford updated 4/21/2005 to correct for missing area. The south west side of Santa Cruz Island, between Morse Pt. and Fraser Pt. was not photographed, due to persistent cloud cover. The south west corner of San Clemente Island, between China Pt. and 32 degrees, 50 minute N, or approximately 2 miles was not photographed due to persistent clould cover. This image file was created from Digital Multi-Spectral Video image files. The original .IMG files created by the DMSV were converted to .FXD files to assure spectral resolution and integrity by a batchfix MS-DOS program. The images were then imported into TNTMips software and georeferenced using DOQs from the United States Geological Survey. After the images had been georeferenced they were re sampled to a 2 meter cell size using a nearest neighbor method designed by Microimages Inc. Areas with a high glint factor (reflection from the sun on choppy water) were extracted to enhance the classification process. All of the images were then mosaiced based on an affine feathering method. The images were subsequently feature mapped and automatically classified to display areas of kelp. The resampled and classified image was then exported into a Arcview TIF file. The TIF file was converted into and Arcview Grid to calculate area. The GRID data was then converted to ESRI shapefile format for display purposes using a weed tolerance of 1.35. DISCLAIMER The user is cautioned against making direct comparisons between the various kelp surveys for the following reasons: 1) Timing of the survey is important, particularly with respect to growing season conditions in the ocean, and storms and harvest levels preceding the dates of survey photography. Seasonal variability may account for differences in surveys, which may not reflect a change in the bed's extent, productivity, or harvest level. 2) Statistical significance in change of area should be evaluated. To do this, a variance parameter is needed, which is obtained by repeated measurements. Most of the coastline, however, has been surveyed only on five occasions (1967, 1989, 1999, 2002, 2003). 3) Survey methods have not been/may not be consistent. Some method of calibration between the methods needs to be performed in order to insure a change of area is not due to survey instrumentation, and not misinterpreted as a biological change. 4) An area where apparently no kelp data are present may truly represent an area devoid of kelp, or may represent an area where kelp was not detected due to poor photo quality, missing photo coverage, or other issues with data collection and processing. Photo coverage is extensive for the state, but the user is advised to consult the photo index for each year to determine whether photographs were acquired for an area of interest.
|
