Dataset: Sea urchin (Eucidaris) quadrat counts at twelve sites in the Galápagos Islands in 2016-2017

ValidatedFinal no updates expectedDOI: 10.26008/1912/bco-dmo.872905.1Version 1 (2022-04-11)Dataset Type:Other Field Results

Principal Investigator: Jon D. Witman (Brown University)

BCO-DMO Data Manager: Dana Stuart Gerlach (Woods Hole Oceanographic Institution)


Project: RAPID: Testing the ability of the 2015-2017 El Nino Southern Oscillation (ENSO) to drive a community-level regime shift in the Galapagos marine ecosystem (SPONGERAPDGALPGS)


Abstract

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.  

 


Related Datasets

IsSupplementedBy

Dataset: Measurement Sites
Relationship Description: Measurement site locations for current dataset
Witman, J. D. (2017) Measurement site locations from RAPDGALPGS project in the Eastern Tropical Pacific, Galapagos Islands, Ecuador in 2015 and the SPONGERAPDGALPGS project in 2016 and 2017. Biological and Chemical Oceanography Data Management Office (BCO-DMO). Version Date 2017-03-03 http://lod.bco-dmo.org/id/dataset/628159

Related Publications

Methods, Results

Witman, J. D., & Smith, F. (2003). Rapid community change at a tropical upwelling site in the Galapagos Marine Reserve. Biodiversity and Conservation, 12(1), 25–45. https://doi.org/10.1023/a:1021200831770
Methods

Lamb, R. W., Smith, F., Aued, A. W., Salinas-de-León, P., Suarez, J., Gomez-Chiarri, M., Smolowitz, R., Giray, C., & Witman, J. D. (2018). El Niño drives a widespread ulcerative skin disease outbreak in Galapagos marine fishes. In Scientific Reports (Vol. 8, Issue 1). Springer Science and Business Media LLC. https://doi.org/10.1038/s41598-018-34929-z