Dataset: Benthic invertebrate abundances associated with octocoral forests in St. John, US Virgin Islands from July 2019 to Jan 2020

Final no updates expectedDOI: 10.26008/1912/bco-dmo.892248.1Version 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 benthic invertebrates counted in association with various octocoral canopies as well as the composition of individual octocorals and the physical parameters (mean height, mean closure, and density) of octocoral canopies. These data were used to test for the association of benthic invertebrate communities across a gradient of octocoral forest formation. Arborescent octocorals were excluded from invertebrate counts used to test for community association. Benthic survey...

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This research was conducted from the University of the Virgin Islands Marine Station in Lameshur Bay St. John, U.S. Virgin Islands at depth ≤ 13 m during July – August 2019 and January 2020.

Methods & Sampling:

Benthic surveys of invertebrates and octocoral forests were conducted using the same quadrats (1 m2) on SCUBA during July – August of 2019 and in January of 2020 placed at ≤ 13-m depth. Quadrats were randomly placed along 20 m, non-overlapping transects that were positioned haphazardly along fringing reefs.Unitary organisms were recorded as individuals, and encrusting modular organisms were counted by the number of autonomous patches of biomass, with both expressed as organisms quadrat-1. Organisms were identified in situ or with reference photos (18.2 megapixels) using field guides (Humann et al., 2013), expert opinion (mostly for sponges), and an electronic reference catalog (Zea et al., 2014). Surveys were conducted at the Cabritte Horn, Tektite, and White Point study sites. Arborescent octocorals with their holdfasts present in the quadrat were measured and contributed to mean height, and density of octocoral canopy measurements. Octocoral height was quantified by measuring the distance from hold fast to to the most distal branch perpendicular to the benthos.

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)
Transect tapes
Measuring ribbons with mm graduations
GoPro Hero 3+ camera
Sony Cybershot DSC-WX300/B


Related Datasets

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: Canopy Closure Data of the Octocoral Forests sampled for Light Intensity, 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) 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 doi:10.26008/1912/bco-dmo.892323.1
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