Coral Settlement and Post-Settlement Mortality on Artificial Substrata in South Mexican Pacific Reefs

Abstract

Coral settlement and post-settlement processes occurring from the time the corals settle to their recruitment determines much of coral population demographics, reef structure, and function. However, the settlement and the survival rate of corals after settling in the Eastern Tropical Pacific (ETP) area are scarcely known. With the aid of a fluorescent lamp, we evaluated the spatial and temporal settlement and post-settlement coral mortality in coral communities and reefs located in the South Mexican Pacific (SMP), using settlement tiles evaluated approximately monthly over a two-year period. No Pocillopora spp. or Pavona spp. were recruited to the tiles, while Porites panamensis settled at lower rates as compared to previous studies in the SMP, which is likely related to the strong El Nino Southern Oscillation anomaly recorded during 2010–2011. During September 2010 and January 2011, P. panamensis settled on the tiles at the highest rate in some locations, suggesting that larval supply and/or environmental conditions affecting settlement in the area varies considerably across space and time. Overall, P. panamensis recruits died at variable rate, ranging from 20% to 100% (∼1.64% per day) during the first 50 days after settling to a substrate. The sizes of the coral spats as well as recruit survival increased significantly throughout time in the area. The null settlement rate of Pocillopora spp. and Pavona spp. compared to P. panamensis is consistent with life history trade-offs, whereas P. panamensis is a better colonizing species and Pocillopora spp. is a better competitor. These factors may allow Pocillopora spp. to outlast P. panamensis, thus becoming the dominant frame-building coral in the SMP and elsewhere in the ETP.