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To evaluate the effects of temperature and pC[O.sub.2] on coral larvae, brooded larvae of Pocillopora damicornis from Nanwan Bay, Taiwan (21[degrees]56.179'N, 120[degrees]44.85'E), were exposed to ambient (419-470 [micro]atm) and high (604-742 [micro]atm) pC[O.sub.2] at ~25 and ~29[degrees]C in two experiments conducted in March 2010 and March 2012. Larvae were sampled from four consecutive lunar days (LD) synchronized with spawning following the new moon, incubated in treatments for 24 h, and measured for respiration, maximum photochemical efficiency of PSII ([F.sub.v]/[F.sub.m]), and mortality. The most striking outcome was a strong effect of time (i.e., LD) on larvae performance: respiration was affected by an LD x temperature interaction in 2010 and 2012, as well as an LD x pC[O.sub.2] x temperature interaction in 2012; [F.sub.v]/[F.sub.m] was affected by LD in 2010 (but not 2012); and mortality was affected by an LD x pC[O.sub.2] interaction in 2010, and an LD x temperature interaction in 2012. There were no main effects of pC[O.sub.2] in 2010, but in 2012, high pC[O.sub.2] depressed metabolic rate and reduced mortality. Therefore, differences in larval performance depended on day of release and resulted in varying susceptibility to future predicted environmental conditions. These results underscore the importance of considering larval brood variation across days when designing experiments. Subtle differences in experimental outcomes between years suggest that transgenerational plasticity in combination with unique histories of exposure to physical conditions can modulate the response of brooded coral larvae to climate change and ocean acidification., Introduction Tropical coral reefs are threatened by global climate change (GCC) and ocean acidification (OA), with large numbers of corals killed by bleaching since the 1980s (Hoegh-Guldberg 1999), and the [...]

The role of habitat‐forming species in promoting biodiversity is widely acknowledged to vary across environmental gradients according to the extent to which they modify resources and environmental conditions. Population‐ and individual‐level traits of habitat‐forming species that influence species interactions may vary across gradients, but the importance of this indirect effect of environmental context is seldom considered. Here, we conducted surveys and field experiments to partition the effects of wave exposure on habitat‐provisioning for invertebrates by oysters into direct and indirect effects, arising from morphological variation of the oysters. A survey of nine sites with varying degrees of wave exposure in Port Jackson, Australia revealed a decline in oyster densities and surface area as wave energy increased. Correlated to declining oyster surface area was a decrease in the richness and abundance of associated invertebrates. By contrast, taxon diversity increased with increasing wave energy. Experimental deployments of oysters at high and low wave energy sites confirmed that variations in oyster morphology was a phenotypically plastic response to environmental conditions. Oyster recruitment was also lower at high as compared to low wave energy sites, further contributing to the variation in oyster habitat among sites. A colonisation experiment in which exposed and sheltered morphologies of oysters were deployed under high and low wave energy conditions in a fully orthogonal design found that invertebrate communities were influenced by both the wave energy of sites and by habitat structure. Our study suggests that in some instances the indirect effects of environment on habitat availability, arising from changes in habitat‐forming species density and morphology, may be as, or even more, important than the direct effects. Understanding how traits of habitat‐forming species respond to environmental conditions, and how intraspecific trait‐variation cascades to influence associated communities is critical to predicting when and where positive species interactions will be greatest. [ABSTRACT FROM AUTHOR]

We tested the effects of pCO2 on Seriatopora caliendrum recruits over the first 5.3d of post-settlement existence. In March 2011, 11–20 larvae were settled in glass vials (3.2mL) and incubated at 24.0°C and ~250μmolquantam−2 s−1 while supplied with seawater (at 1.4mLs−1) equilibrated with 51.6Pa pCO2 (ambient) or 86.4Pa pCO2. At 51.6Pa pCO2, mean respiration 7h post-settlement was 0.056±0.007nmolO2 recruit−1 min−1, but rose quickly to 0.095±0.007nmolO2 recruit−1 min−1 at 3.3d post-settlement, and thereafter declined to 0.075±0.002nmolO2 recruit−1 min−1 at 5.3d post-settlement (all±SE). Elevated pCO2 depressed respiration of recruits by 19% after 3.3d and 12% overall (i.e., integrated over 5.3d), and while it had no effect on corallite area, elevated pCO2 was associated with weaker adhesion to the glass settlement surface and lower protein biomass. The unique costs of settlement and metamorphosis for S. caliendrum over 5.3d are estimated to be 257mJrecruit−1 at 51.6Pa pCO2, which is less than the energy content of the larvae and recruits. [ABSTRACT FROM AUTHOR]

Manipulative studies have demonstrated that ocean acidification (OA) is a threat to coral reefs, yet no experiments have employed diurnal variations in pCO(2) that are ecologically relevant to many shallow reefs. Two experiments were conducted to test the response of coral recruits (less than 6 days old) to diurnally oscillating pCO(2); one exposing recruits for 3 days to ambient (440 µatm), high (663 µatm) and diurnally oscillating pCO(2) on a natural phase (420-596 µatm), and another exposing recruits for 6 days to ambient (456 µatm), high (837 µatm) and diurnally oscillating pCO(2) on either a natural or a reverse phase (448-845 µatm). In experiment I, recruits exposed to natural-phased diurnally oscillating pCO(2) grew 6-19% larger than those in ambient or high pCO(2). In experiment II, recruits in both high and natural-phased diurnally oscillating pCO(2) grew 16 per cent larger than those at ambient pCO(2), and this was accompanied by 13-18% higher survivorship; the stimulatory effect on growth of oscillatory pCO(2) was diminished by administering high pCO(2) during the day (i.e. reverse-phased). These results demonstrate that coral recruits can benefit from ecologically relevant fluctuations in pCO(2) and we hypothesize that the mechanism underlying this response is highly pCO(2)-mediated, night-time storage of dissolved inorganic carbon that fuels daytime calcification.