High Latitude Coral Larval Recruitment: Spatiotemporal Process Variability in the Gulf of California1

Abstract: The aim of this study is to explore if sexual reproduction is present in scleractinian corals at the northern limit of their distribution (28.980° N, 113.470° W) in a zone subject to upwelling and seasonal variations in sea surface temperature, and sampling was performed from August 2018 to October 2019. We placed 42 terracotta recruitment tiles in Bahía de los Ángeles, Baja California. Coral cover was estimated, and the height, major diameter, and minor diameter of coral colonies were measured. Astrangia haimei and Porites panamensis recruits were identified on the recruitment tiles, constituting the first quantitative record for the northeastern tropical Pacific. Recruitment of P. panamensis was higher (Llave: 63.09 ± 114 ind m–2 y–1, Rasito: 3.21 ± 7 ind m–2 y–1), while A. haimei recruitment at the same sites was 3.85 ± 8 and 1.93 ± 6 ind m–2 y–1, respectively. Recruitment differences between locations were attributed to coral cover (the abundance of Porites panamensis is 15-fold greater in Llave than in Rasito) and colony size (P. panamensis Llave: 10.53 ± 5.93 cm, Rasito: 4 ± 0.63 cm). Both SST and Chl-a concentrations were also highly correlated with coral recruitment, with higher recruitment rates observed in the warmer seasons when high nutrient concentrations were also present. In contrast to other sites in the eastern tropical Pacific, the highest rate of recruitment was reported at this study (high-latitude coral community), which, according with the positive high latitude trend reported by other studies, is likely due to climate change.