Settlement ecology of scleractinian corals of the Northeastern Tropical Pacific

Abstract

Reproduction and recruitment are essential processes for the continued success of coral communities. Islas Marias Archipelago is considered a connectivity node among coral communities distributed along the Northeastern Tropical Pacific (NTP); as such, sexual reproduction of scleractinian corals affects the maintenance of the local populations and the long-distance connectivity of reefs across the region. In this study, successful sexual reproduction in the species of the three most abundant scleractinian corals genera was demonstrated, in part by documenting gamete presence and maturation in tissues and spatio-temporal variability in juvenile coral settlement, which were quantified across substrate type, habitat quality, and environmental factors. Only 12 larvae recruited (ten Porites, two Pavona) to artificial substrates, and monthly recruitment density of 1.82 ± 0.23 recruits m−2 (n = 383) was recorded on natural substrates. There were significant differences between genera, with Porites producing the highest density of recruits (0.60 ± 0.45 recruits m−2, followed by Pavona (0.52 ± 0.24 recruits m−2) and Pocillopora (0.28 ± 0.06 recruits m−2). The highest coral recruitment was observed at Baby Reef (2.57 ± 0.46 recruits m−2), followed by Cleofas II (1.81 ± 0.21 recruits m−2) and Japanese Garden (1.24 ± 0.46 recruits m−2); the former site was characterized by the highest cover of crustose coralline algae. We found successful recruitment of the main reef-forming species in the Mexican Pacific and suggest that Islas Marias is a region of critical importance in terms of its function as a source of genetic variability, and, the generation of, new individuals that will be key to sustaining coral reef ecosystems in the NTP.