Landscape-scale variation in coral recruitment in Moorea, French Polynesia

Abstract

In this study, we describe spatio-temporal variation in coral recruitment in the back reef of Moorea, French Polynesia, and explore the extent to which it is associated with community structure, seawater temperature, and wave regimes. Recruitment was assessed with settlement tiles deployed at 10 sites on the north, southeast, and southwest shores and sampled every 5 to 7 mo from 2005 to 2007. Temperature and waves were measured using thermistors and pressure sensors, and community structure was assessed using in situ surveys. Mean recruitment varied from 0 to 6 recruits tile -1 (510 cm 2 ) and was generally greater in the second compared to the first year of the study. Recruitment varied among sites, and this variation was similar between years but differed among sampling periods: acroporids were common on the southwest shore between January and September, but rare from September to January; poritids were common on the north shore between September and January, but rare on the southwest shore from January to September; and pocilloporids were found all year, but at slightly elevated densities between January and September. The mean daily seawater temperature, and the daily range, varied among sites, but neither was closely related to coral recruitment, and both were of biologically small magnitudes. The coral community structure also varied among sites, but likewise, was not associated with coral recruitment. In contrast, outer reef wave energy exposure, which likely played an important role in driving cross-reef transport of seawater into the lagoon, differed between shores and seasons in a pattern consistent with the variation in coral recruitment in the back reef. We hypothesize that coral recruitment in the back reef of Moorea is influenced by the interaction of seasonal variation in wave exposure, family-level differences in coral reproductive timing, and the spatial distribution of adult corals.

Size-dependent physiological responses of the branching coralPocillopora verrucosato elevated temperature andPCO2

“…The temperatures represented the seasonal range for seawater in Moorea (Edmunds et al, 2010) and the elevated P CO2 represented a pessimistic projection for atmospheric P CO2 by the end of the present century (Representative Concentration Pathway, RCP 8.5) (Riahi et al, 2007;van Vuuren et al, 2011). Seawater in each tank was independently chilled, heated, and circulated with a water pump, and tanks were illuminated (with SOL White LED, 6500 K, Aqua-Illumination) at a target PAR of ∼650 µmol photons m −2 s −1 (measured with a LiCor 4-π quantum sensor .…”

Diel pCO2 oscillations modulate the response of the coral Acropora hyacinthus to ocean acidification

“…This outcome was likely due to the small diel variation in pCO 2 that we detected (69 versus 85 µatm at upstream and downstream habitats), which is much lower than the very large daily variation in pCO 2 recently recorded in reef waters at Lady Elliot Island, Australia (Shaw et al 2012). While it is currently unknown why upstream−downstream variation in pCO 2 in reef waters in Moorea was so small at the time of measurement, it is possible that contempo-rary values reflect the low coral cover in the back reef of Moorea (Edmunds et al 2010, Trapon et al 2011), the strong cross reef transport of seawater in Moorea that lessens residence time of water over the reef (e.g. Rosman & Hench 2011), and the greater depth of water (~2 m) compared to Lady Elliot Island (~0.4 m) where diel pCO 2 variation is strongly developed (Shaw et al 2012).…”

“…Temperature was kept at 27°C, which is close to the seawater temperature in the lagoon of Moorea in August (Edmunds et al 2010). Seawater was supplied from 12 m depth in Cook's Bay, filtered (pore size ~100 µm), and delivered to the tanks at ~150 ml min −1…”

Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification

“…B 281: 20141339 resources to reproduction, P. damicornis releases larvae year round [47,48] and massive Porites spp. were likely to be at a similar stage of their reproductive cycle [47,48]. Therefore, reproduction is unlikely to have an interactive effect with the timing of our experiments.…”