Octocoral species abundance during transect surveys at four sites on the south shore of St. John, US Virgin Islands from November to December 2017 (NCEI Accession 0278394)

Acquisition Description:
Survey design:
All sites were located at 6 to 9 meters depth.

Censuses at East Cabritte, Europa and Tektite were based on 50x10m areas that were arbitrarily selected and permanently marked with stainless steel eyebolts at the corners of the sites. A total of six transect lines, also marked with eyebolts, were laid out at 10 m intervals. All octocorals present in 1 x 1 m quadrats along the 10-meter long transects were scored. In 2014 ten quadrats were surveyed along each line. In 2015 and 2016 ten quadrats were scored along each transect line at Europa and Tektite and five randomly chosen quadrats were surveyed at East Cabritte. The transect identifier "transect_pos" has values 0, 10, 20, 30, 40 or 50 which represent position in meters within the 50x10 survey area corresponding to each of the 6 transects (e.g. 20 = 20m).

The census at Booby Rock was conducted in a single day in which 2 transects were randomly placed along a 50 m line that was arbitrarily placed on a constant depth contour. Only 4 1x1 m quadrats were surveyed along each transect. The transect identifier (transect_pos) for transects at Booby Rock refers to position along the 50 m line.

Sampling methods:
Identifications were based on traits visible in the field, and samples of representative colonies were collected for further analysis in cases in which field identification was uncertain. Sclerites from those samples were examined for species identification.

Colony heights were measured as the maximum distance from the base of the octocoral colony until the farthest tips of the branch (i.e. not necessarily perpendicular to the substrate). All measures rounded to the nearest cm with the exception of 5 cm which only includes colonies >= 5 cm. Starting in 2016, measures less than 5 cm reflect colonies with thick branches which could only have <5 cm heights due to partial mortality.

Two height measures are present, height of living tissue, which only includes that part of the axis with living tissue and total height which is the distance from the base to the tip of the tallest branch regardless of whether the tips or base had living tissue. (Only colonies with some living tissue were measured).

Species names for field_codes in this dataset can be found in the related dataset: https://www.bco-dmo.org/dataset/733063

These data are a continuation of BCO-DMO project "Ecology and functional biology of octocoral communities" (http://www.bco-dmo.org/project/562086)