Peyssonnelia abundance along the south shore of St. John, US Virgin Islands from surveys during 2015

<p>The abundance of the peyssonnelid algal crust was measured using 50 m video transects (recorded with a GoPro Hero 3) at 3, 5, and 7 m depth at five sites, haphazardly selected between Cabritte Horn and White Point on the south shore of St. John. Still images (n = 20 transect-1, each ~ 250 cm2) were randomly extracted and analyzed for percentage cover of peyssonnelids using a grid of 25 squares that were scored for dominance by this alga (i.e., 4% resolution).</p>