Dataset: Canopy closure values from photographs taken within octocoral forestsalong the south shore of St. John, U.S. Virgin Islands in March of 2019

Final no updates expectedDOI: 10.26008/1912/bco-dmo.892323.1Version 1 (2023-03-21)Dataset Type:Other Field Results

Principal Investigator: Peter J. Edmunds (California State University Northridge)

Student: John Girard (California State University Northridge)

BCO-DMO Data Manager: Amber D. York (Woods Hole Oceanographic Institution)


Project: Collaborative Research: Pattern and process in the abundance and recruitment of Caribbean octocorals (Octocoral Community Dynamics)

Project: RUI: Pattern and process in four decades of change on Caribbean reefs (St John Coral Reefs)


Abstract

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...

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Location:
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


Related Datasets

IsRelatedTo

Dataset: Benthic Invertebrate Abundances associated with Octocoral Forests of St. John, US Virgin Islands
Relationship Description: Octocoral measurements and invertebrate counts were done in the same quadrats. Therefore, the quadrat IDs correspond to each other across community & canopy data sets.
Girard, J., Edmunds, P. J. (2023) Benthic invertebrate abundances associated with octocoral forests in St. John, US Virgin Islands from July 2019 to Jan 2020. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2023-03-21 doi:10.26008/1912/bco-dmo.892248.1
IsRelatedTo

Dataset: St. John Octocoral Forest Closure Photo Analysis for Community Quadrats
Relationship Description: Octocoral measurements and invertebrate counts were done in the same quadrats. Therefore, the quadrat IDs correspond to each other across community & canopy data sets.
Girard, J., Edmunds, P. J. (2023) Canopy closure values from photographs taken within octocoral forests in Lameshur Bay St. John, U.S. Virgin Islands from July 2019 to Jan 2020. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2023-03-21 doi:10.26008/1912/bco-dmo.892258.1
IsRelatedTo

Dataset: Light intensity measurements associated with Octocoral Canopies from East Cabritte, St. John, U.S. Virgin Islands
Relationship Description: Octocoral measurements and invertebrate counts were done in the same quadrats. Therefore, the quadrat IDs correspond to each other across community & canopy data sets.
Girard, J., Edmunds, P. J. (2023) Light intensity (lux) of downwelling light upon the benthos along differing conditions of octocoral canopy formation in East Cabritte, in Grootpan Bay, 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 doi:10.26008/1912/bco-dmo.892300.1
IsRelatedTo

Dataset: Light intensity measurements associated with Octocoral Canopies from Yawzi Point, St. John, U.S. Virgin Islands
Relationship Description: Octocoral measurements and invertebrate counts were done in the same quadrats. Therefore, the quadrat IDs correspond to each other across community & canopy data sets.
Girard, J., Edmunds, P. J. (2023) Light intensity (lux) of downwelling light upon the benthos along differing conditions of octocoral canopy formation in Lameshur Bay 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 doi:10.26008/1912/bco-dmo.892272.1
IsRelatedTo

Dataset: Octocoral Sensus Data for Light Quadrats at Yawzi Point and East Cabritte sites in St. John, U.S. Virgin Islands
Relationship Description: Octocoral measurements and invertebrate counts were done in the same quadrats. Therefore, the quadrat IDs correspond to each other across community & canopy data sets.
Girard, J., Edmunds, P. J. (2023) Octocoral canopy metrics (mean height, density, and closure) in St. John, US Virgin Islands in March of 2019. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2023-03-21 doi:10.26008/1912/bco-dmo.892293.1

Related Publications

Results

Girard, J. F., & Edmunds, P. J. (2023). Effects of arborescent octocoral assemblages on the understory benthic communities of shallow Caribbean reefs. Journal of Experimental Marine Biology and Ecology, 561, 151870. https://doi.org/10.1016/j.jembe.2023.151870
Methods

GoPro (2013). Hero 3 silver edition: user manual. 1–62. https://gopro.com/content/dam/help/hero3-silver-edition/manuals/HERO3_Silver_UM_ENG_RevC_web.pdf. Accessed: 21/Dec/2022
Methods

Jennings, S. (1999). Assessing forest canopies and understorey illumination: canopy closure, canopy cover and other measures. Forestry, 72(1), 59–74. https://doi.org/10.1093/forestry/72.1.59
Software

Schneider, C. A., Rasband, W. S., & Eliceiri, K. W. (2012). NIH Image to ImageJ: 25 years of image analysis. Nature Methods, 9(7), 671–675. https://doi.org/10.1038/nmeth.2089