Prior to the 2017 hurricanes, six shallow (8-15 m depth) reef sites had been selected from the Virgin Islands Territorial Coral Reef Monitoring Program\u2019s (TCRMP) permanent monitoring sites to study variation in sponge communities in St. Thomas. These sites included Black Point (N18\u00b0\u00a020.665\u2019, W64\u00b0\u00a059.107\u2019), Coculus Rock (N18\u00b0\u00a018.734\u2019, W64\u00b0\u00a051.613\u2019), and Magens Bay (N18\u00b0 22.459\u2019, W64\u00b0 56.077\u2019), which are in embayments with heavily developed watersheds. Buck Island (N18\u00b0 16.717\u2019, W64\u00b0 53.925\u2019) and Savana Island (N18\u00b0\u00a020.437\u2019, W65\u00b0\u00a004.939\u2019) are located near undeveloped offshore cays. Botany Bay (N18\u00b0\u00a021.433\u2019, W65\u00b0\u00a002.071\u2019) is a nearshore site in a bay with a low level of watershed development. For this study, we used three randomly selected transects out of the six permanently established 10 m TCRMP transects at each site. The same three transects at each site were re-surveyed repeatedly in August 2015, August 2016 (pre-hurricanes) and December 2017 (10 weeks post-hurricanes).\u00a0
\n
At each site, sponge volume was calculated within permanent 1 m2\u00a0quadrats centered on the transect line within the initial and/or final meter of the transect. Sponge volume was calculated for 3-5 quadrats per site. As there were over 80 species of sponges within our survey areas, representing a wide diversity of morphologies, we chose to use a standardized measurement approach for all sponges, rather than calculating the true volumetric measurement for each sponge based on its actual morphology. Thus, sponges were essentially treated as cuboids. We used a flexible sewing tape to measure the longest dimension of the sponge, then one to several width measurements perpendicular to the initial length measurement, and one to several height measurements, as needed to represent the shape and dimensions of each sponge. Multiple measurements for each dimension were averaged and length x width x height was calculated. For large tubes, of which there were relatively few, we subtracted the dimensions of the interior cavity from the exterior dimensions of the sponge. Generated data were in cm3 of sponge/m2 (Gochfeld et al. 2020).
This dataset includes total sponge volume in\u00a0quadrats\u00a0at\u00a0six sites in Virgin Islands Territorial Coral Reef Monitoring Program,\u00a0pre- and post-hurricane, 2015-2017.
\n
These data were published in Gochfeld et al (2020).
To test for hurricane effects on various metrics of the sponge community, repeated measures analyses of variance (ANOVA) were performed on sponge volume, with site as a random factor, using the lmer function in the lme4 package in R (Bates et al. 2015). Square-root transformations were performed to meet the assumptions of parametric analysis. For significant effects, post-hoc comparisons were performed using the lumens function with the Tukey correction specified in R. To characterize hurricane effects on sponges with differing morphologies, a repeated measures ANOVA was also performed on arcsine transformed proportions to test for the main effect of year, using site as a random factor, followed by least square means post-hoc tests where warranted (Gochfeld et al. 2020).
\n
BCO-DMO Processing Notes:
\n- added conventional header with dataset name, PI names, version date
\n- modified parameter names to conform with BCO-DMO naming conventions
\n- added site_name, site_description, lat and lon columns (converted lat and lon to decimal degrees)