Health of tropical coral reefs depends largely on the balance between constructive (calcification and cementation) and destructive forces (mechanical-chemical degradation). Gradual increase in dissolved CO 2 and the resulting decrease in carbonate ion concentration ("ocean acidification") in ocean surface water may tip the balance toward net mass loss for many reefs. Enhanced nutrients and organic loading in surface waters ("eutrophication"), may increase the susceptibility of coral reef and near shore environments to ocean acidification. The impacts of these processes on coral calcification have been repeatedly reported, however the synergetic effects on bioerosion rates by sponges are poorly studied. Erosion by excavating sponges is achieved by a combination of chemical dissolution and mechanical chip removal. In this study, Cliona caribbaea, a photosymbiont-bearing excavating sponge widely distributed in Caribbean reef habitats, was exposed to a range of CO 2 concentrations, as well as different eutrophication levels. Total bioerosion rates, estimated from changes in buoyant weights over 1 week, increased significantly with pCO 2 but not with eutrophication. Observed chemical bioerosion rates were positively affected by both pCO 2 and eutrophication but no interaction was revealed. Net photosynthetic activity was enhanced with rising pCO 2 but not with increasing eutrophication levels. These results indicate that an increase in organic matter and nutrient renders sponge bioerosion less dependent on autotrophic products. At low and ambient pCO 2 , day-time chemical rates were ∼50% higher than those observed at night-time. A switch was observed in bioerosion under higher pCO 2 levels, with night-time chemical bioerosion rates becoming comparable or even higher than day-time rates. We suggest that the difference in rates between day and night at low and ambient pCO 2 indicates that the benefit of acquired energy from photosynthetic activity surpasses the positive effect of increased pCO 2 levels at night due to holobiont respiration. This implies that excavation must cost cellular energy, by processes, such as ATP usage for active Ca 2+ and/or active proton pumping. Additionally, competition for dissolved inorganic carbon species may occur between bioerosion and photosynthetic activity by the symbionts. Either way, the observed changing role of symbionts in bioerosion can be attributed to enhanced photosynthetic activity at high pCO 2 levels.

Excavating sponges are among the most important macro-eroders of carbonate substrates in marine systems. Their capacity to remove substantial amounts of limestone makes these animals significant players that can unbalance the reef carbonate budget of tropical coral reefs. Nevertheless, excavating sponges are currently rarely incorporated in standardized surveys and experimental work is often restricted to a few species. Here were provide chemical and mechanical bioerosion rates for the six excavating sponge species most commonly found on the shallow reef of Curaçao (southern Caribbean): Cliona caribbaea, C. aprica, C. delitrix, C. amplicavata, Siphonodictyon brevitubulatum and Suberea flavolivescens. Chemical, mechanical and total bioerosion rates were estimated based on various experimental approaches applied to sponge infested limestone cores. Conventional standing incubation techniques were shown to strongly influence the chemical dissolution signal. Final rates, based on the change in alkalinity of the incubation water, declined significantly as a function of incubation time. This effect was mitigated by the use of a flow-through incubation system. Additionally, we found that mechanically removed carbonate fragments collected in the flow-through chamber (1 h) as well as a long-term collection method (1 wk) generally yielded comparable estimates for the capacity of these sponges to mechanically remove substratum. Observed interspecific variation could evidently be linked to the adopted boring strategy (i.e. gallery-forming, cavity-forming or network-working) and presence or absence of symbiotic zooxanthellae. Notably, a clear diurnal pattern was found only in species that harbour a dense photosymbiotic community. In these species chemical erosion was substantially higher during the day. Overall, the sum of individually acquired chemical and mechanical erosion using flow-through incubations was comparable to rates obtained gravimetrically. Such consistency is a first in this field of research. These findings support the much needed confirmation that, depending on the scientific demand, the different approaches presented here can be implemented concurrently as standardized methods.

Pregnant women should receive information about what they might expect to experience during their delivery. Despite this, research shows many women are inadequately prepared for anaesthetic interventions during labour. We surveyed 903 postnatal women across 28 Greater London hospitals about: the analgesic and anaesthetic information that they recalled receiving during pregnancy and delivery; their confidence to make decisions on analgesia; and their satisfaction with the analgesia used. Wide variation was observed between hospitals. Overall, 67 of 749 (9.0%) women recalled receiving antenatal information covering all aspects of labour analgesia, and 108 of 889 (12.1%) covering anaesthesia for caesarean section. Regarding intrapartum information, 256 of 415 (61.7%) respondents recalled receiving thorough information before epidural insertion for labour analgesia, and 102 of 370 (27.6%) before anaesthesia for caesarean section. We found that 620 of 903 (68.7%) women felt well enough informed to be confident in their analgesic choices, and 675 of 903 (74.8%) stated that their analgesia was as expected or better. Receiving information verbally, regardless of provider, was the factor most strongly associated with respondents recalling receiving full information: odds ratio (95%CI) for labour analgesia 20. 66 (8.98-47.53; p < 0.0001); epidural top-up for caesarean section 5. 93 (1.57-22.35; p = 0.01); and general anaesthesia for caesarean section 12. 39 (2.18-70.42; p = 0.01). A large proportion of respondents did not recall being fully informed before an anaesthetic intervention. Collaboration with current antenatal service providers, both in promoting information delivery and providing resources to assist with delivery, could improve the quality of information offered and women's retention of that information.