The intertidal rocky shore of Bahía Panama, within Bahía Culebra in the North Pacific coast of Costa Rica, was sampled to study the biodiversity and the spatial patterns (three sites with differences in wave exposure, and five strata, from low to high tide levels) and temporal variation (a single date in 2007 and 2013) in different microhabitats (over and under rock surface, and crevices). The epibenthic organisms were sampled with quadrats of 25 x 25 cm in each stratum, and cryptic fauna was accounted by both visual census and manual collecting. The general pattern of vertical zonation of organisms at each site showed an increase in variety toward the infralittoral level, as well as in the composition of assemblages or partially in identity of taxa in each stratum. The sheltered section of the rocky coast, with shallow sand bottom (< 1 m), low wave action and greater sedimentation rate, had lower diversity, cover and abundance that increased towards the wave-exposed section, with more abrupt slope in the edge of rocky platform, lower turbidity, and deeper sand bottom (2-3 m). The horizontal change was more evident in epibenthic organisms, followed by the under rock surface inhabitants and finally in crevices. For the epibenthic organisms, a temporal change in assemblages (cover and abundance) was found between the 2007 and 2013, at each site and level (possibly by seasonal upwelling influence), but the spatial structure (vertical and horizontal) of the rocky shore seems the main cause of change in the composition of species. The spatial pattern of change in the biota (sheltered to exposed gradient) could be expected in similar shores of the Central American Pacific. Finally, the 157 species found (16 autotrophic taxa, 22 fishes, and 119 invertebrates) indicate the high biodiversity of this habitat in the tropics, and the importance of their conservation. Rev. Biol. Trop. 62 (Suppl. 4): 85-97. Epub 2014 Diciembre 01.

Keywords: assemblage variability, invertebrates, microhabitats, marine biodiversity.