These data represent the determination of canopy closure values from photographs taken within octocoral forests along the south shore of St. John, U.S. Virgin Islands. Sampling was performed during March 2019 in quadrats (1m2) placed at ~8–9-m depth. These data were recorded in conjunction with light intensity measurements and used to investigate the relationship between octocoral canopy metrics and evidence of sunflecking in the understory environment. These data were collected as part of an...
Show moreLocation:
Yawzi Point and East Cabritte sites along the south shore of St. John, U.S. Virgin Islands at ~8–9-m depth
Research conducted from the University of the Virgin Islands Marine Station in Lameshur Bay during March 2019.
Methods & Sampling:
Canopy closure was quantified using a modified method from (Jennings et. al. 1999) whereby a GoPro Hero 3+ camera with a 130° field of view (manufacturer’s specification, Go-Pro., Inc. San Mateo, CA) was used to record still images in the center, and at each of the four corners, of quadrats, with all five images quadrat-1 recorded within < 5 minutes. To avoid biases in estimating canopy closure caused by adjacent non-living substrata (e.g., boulders and rock walls), images were excluded when they included these features. Images were analyzed using ImageJ software (v1.52a, Schneider et al., 2012), in which 300 randomly located dots (~ 0.5 pixel in diameter) were superimposed on each image. The number of dots on the octocoral canopy were counted and expressed as a percentage of the dot population. This metric was used to quantify canopy closure, and the results from the five images quadrat-1 were averaged to characterize each quadrat.
Instruments:
PVC Quadrats (1 m2)
GoPro Hero 3+ camera
Girard, J., Edmunds, P. J. (2023) Canopy closure values from photographs taken within octocoral forestsalong the south shore of St. John, U.S. Virgin Islands in March of 2019. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2023-03-21 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.892323.1 [access date]
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This dataset is licensed under Creative Commons Attribution 4.0.
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