Finding signals in the noise of coral recruitment

Measurements of coral recruitment can improve understanding of coral population dynamics, but in short duration studies high variance impedes interpretation of this vital rate. Here, coral recruitment in Moorea, French Polynesia, was measured over 13 yr and tested for associations with environmental conditions. Recruitment of spawning pocilloporid corals was recorded using settlement tiles immersed for similar to 6 months at 10 m and 17 m depth, biannually, and the environment was quantified through seawater clarity (K-d490), surface and bottom flow speeds, coral cover, and temperature. Using GAMs, most of the variation (63-74%) in recruitment was explained using depth and three predictors. Recruitment was high in January/February following a year of low seawater clarity (high K-d490), and in August/September following a year of high clarity. Recruitment in January/February was elevated by high coral cover, and by high surface flow during larval dispersal; recruitment was low in August/September following high temperature during gametogenesis. These effects reveal the extent to which early life stages of corals are exposed to annually variable environmental conditions that have differential consequences depending on the phenology of reproduction and recruitment. The temporal mosaic defining interactions between reproduction, recruitment, and environmental conditions create opportunities for acclimatization to affect where and when coral recruitment is successful.

Automated summary

Research on coral recruitment in Moorea, French Polynesia, found that recruitment is influenced by seasonal variations and environmental factors such as seawater clarity, flow speeds, coral cover, and temperature. These effects highlight the importance of understanding how early life stages of corals are affected by annual environmental conditions, and the opportunities for acclimatization to impact successful coral recruitment.