Interacting effects of habitat structure and seeding with oysters on the intertidal biodiversity of seawalls

the crest of ridges and the other half (26) were attached in clumps into the crevices. At each site, the tiles were deployed in a single horizontal row. The complex tiles were positioned so that the crevices and ridges were orientated horizontally. Sessile and mobile taxa In situ sampling. One, 6 and 12 months after the tiles were deployed, we assessed the number of live seeded S. glomerata, the percentage cover of oysters and other sessile taxa, and the abundances of mobile taxa on each tile, at low tide during the day. These time points were selected to ensure that sampling was conducted at the beginning, middle and end of the experi- ment, however month was considered a random factor in the analyses (see below) because we had no a priori expectations about the effects of the treatments at these sampling points and our goal was to assess the effects of the treatments over the entire duration of the experiment. The percentage cover of oysters included both live and dead, transplanted and colonising oys- ters summed together as it was not to distinguish between these categories in the photoqua- drats. For each tile, we sampled the percentage cover of S. glomerata and other sessile taxa with 0.25 × 0.25 m photoquadrats, taken at a distance of 0.5 m from the tiles, using an Olympus Tough style camera (TG-860, mode Automatic mode, 16 MP). Using Coral Point Count soft- ware (CPCe) [44], we overlaid 100 randomly generated points on the flat tiles, or 50 points in Fig 1. The four experimental treatments: a) flat unseeded tiles; b) complex unseeded tiles; c) flat seeded tiles; d)

complex seeded tiles. Complex tiles had ridges and crevices; seeding was with the Sydney rock oyster, Saccostrea glomerata. https://doi.org/10.1371/journal.pone.0230807.g001 PLOS ONE Effects of microhabitats and seeding with oysters on intertidal biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0230807 July 16, 2020 5 / 21