Dataset: Octocoral colony heights measured during transect surveys at six sites on the south shore of St. John, US Virgin Islands during July and August of 2024

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. 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 transects were randomly placed along a 50 m line that was arbitrarily placed on a constant depth contour. The transect identifier (transect_pos) for transects at Booby Rock refers to position along the 50 m line.

Yawzi and Deep Tektite surveys: 20 quadrats at each transect (3 transects). Yawzi transects were censused over two field trips, July/August and September.

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.

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 farthest branch from the base (i.e. not necessarily perpendicular to the substrate), regardless of whether the tips or base had living tissue. (Only colonies with some living tissue were measured). 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.

Notes about identifications/codes: 

Octocoral adults are defined as individuals >= 5 cm height.  With height determined to the nearest cm

LINES WITH NO SPECIES ENTRY IDENTIFY QUADRATS IN WHICH NO OCTOCORALS WERE PRESENT-  This is also noted in the comment columns as "No colonies present."

Field identifications of   Eunicea mammosa, E. laxispica and E. succinea  are sometimes difficult, thus, for analysis purposes the three species are lumped as a single group.

Field identifications of  Pseudoplexaura flagellosa and P. wagenaari  are difficult, thus, for analysis purposes the three species are lumped as a single group.

Species_Code aa2 is an undescribed Antillogorgia sp. that is very similar to A. americana and is lumped with A. american for analysis purposes.

Field identifications of   Muricea muricata and M. atlantica  are difficult, thus, for analysis purposes the three species are lumped as a single group.

Notes about Comments columns in this dataset:
  
Millepora present: Inicates millepora overgrowing naked axis
Cyanobacteria present: Indicates Cyanobacteria growing on the colony.
Spo or Sponge indicates sponge growing on the colony, most commonly on bare axis
"pale" or "bleached" indicates partial or complete bleaching of some branches on the colony
"ophio" or "Ophiothela" indicates the presence of Ophiothela mirabilis on the colony 
oyster indicates the presence of oyster(s) growing on the axis of the colony
"fallen" indicates the colony has fallen over but there is living tissue. Heights are based on the length of the living tissue on the substrate measured as if the colony were erect.
"Ophiothrix" indicates the presences of an "Ophiothrix sp." on the colony
"damselfish" indicates the colony was in a damselfish territory and some branches were being "farmed" by the damselfish

See "Parameters" section for more information about each column in this dataset.