Macroalgae and zoanthids require physical contact to harm corals in Southwestern Atlantic

Background (extract from related publication): In coral reefs, sessile competitors can use several mechanisms to outcompete hard corals, most requiring physical contact. Turf algae, macroalgae and zoanthids dominate Southwestern Atlantic (SWA) reefs, however, species-specific responses of corals to competition with these dominant groups are not fully understood, particularly in the Brazilian Province. Here, we assessed the competitive interactions of two coral species, the reef builder S. stellata and the branching M. alcicornis, with two abundant competitors, the macroalga Dictyopteris delicatula and the zoanthid P. caribaeorum.
Methods: We conducted a 26-day laboratory experiment to investigate coral response to two competitive mechanisms: I) physical contact with competitors and II) proximity to competitors. We monitored coral recovery after ceasing the competitive interaction. Coral response to the competitor and coral recovery were evaluated by measuring coral color and photosynthetic efficiency. We tested whether the two competitive mechanisms negatively impacted corals and whether the coral species responded distinctly to the competitors.
Dataset: Data used to run the analyzes reported at the research and published paper are included in an Excel file, with two worksheets containing data on photosynthetic efficiency and tissue damage of corals (Siderastrea sp., here "Sid", and Millepora alcicornis, here "Mil") interacting with competitors: macroalgae (here, "Dict" - Dictyopteris delicatula) and zoanthids (here "Paly" - Palythoa caribaeorum).
PAM readings: photosynthetic efficiency values recorded on corals (C1: corals in physical contact with competitors, C1_contact: contacted area by the competitor, C1_overall: area not contacted by the competitor; C2_overall: corals in proximity with competitors) throughout the experiment (days)
Tissue damage: percent damaged area on corals (C1_contact: corals physically contacting the competitors; C2_prox: corals in proximity with competitors)