File(s) | Type | Description | Action |
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sea_urchin_density.csv (29.05 KB) | Comma Separated Values (.csv) | Primary data file for dataset ID 872905 | Add to Cart Download |
Sea urchin (E. galapagensis) densities showed high variability across twelve study sites in the Galápagos Islands in 2016-2017. Sea urchin densities ranged from a low of 0.17 individuals per 0.25 square meter quadrat at the Pinzon site to a maximum of 7.7 individuals per quadrat at the Champion site in January 2016.
Quadrat survey techniques were used at twelve sites in the Galápagos Islands in 2016-2017 to determine counts and species density of Eucidaris sea urchins. Quadrats were 0.25 square meter areas randomly established following the methods of Witman and Smith (2003). A ‘quadrapod’ camera framer holding an underwater camera was used to capture digital photo quadrat images (42 megapixel resolution) which were subsequently viewed on a computer. This was the same field sampling method described in Witman and Smith (2003) except this study used a Sony AR digital camera in a Nauticam underwater housing. The sampling was achieved by a diver swimming along the transect tape and taking photo quadrats at the random marks on the tape. The large thick spines of the Eucidaris galapagensis enable the sea urchins to be readily recognized and counted. Sea urchins were manually counted from digital images of the quadrats (photo quadrats) displayed on a computer screen. The counts were then entered by quadrat and site into an Excel spreadsheet.
Witman, J. D. (2022) Sea urchin (Eucidaris) quadrat counts at twelve sites in the Galápagos Islands in 2016-2017. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2022-04-11 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.872905.1 [access date]
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