03005nas a2200397   4500008004100000020001400041245008700055210006900142260004600211300001400257490000700271520175100278653001802029653003102047653001502078653001902093653002602112653001902138653001602157653003102173653001902204653001802223653001002241653002202251653001002273653001202283653001502295653001602310100002302326700003302349700003302382700002102415700002602436700001702462856012802479       2013                        eng d  a1354-101300aSponge biomass and bioerosion rates increase under ocean warming and acidification0 aSponge biomass and bioerosion rates increase under ocean warming  aEnglandbWiley Subscription Services, Inc  a3581-35910 v193 aThe combination of ocean warming and acidification as a result of increasing atmospheric carbon dioxide ( CO 2 ) is considered to be a significant threat to calcifying organisms and their activities on coral reefs. How these global changes impact the important roles of decalcifying organisms (bioeroders) in the regulation of carbonate budgets, however, is less understood. To address this important question, the effects of a range of past, present and future CO 2 emission scenarios (temperature + acidification) on the excavating sponge Cliona orientalis Thiele, 1900 were explored over 12 weeks in early summer on the southern Great Barrier Reef. C. orientalis is a widely distributed bioeroder on many reefs, and hosts symbiotic dinoflagellates of the genus Symbiodinium . Our results showed that biomass production and bioerosion rates of C. orientalis were similar under a pre‐industrial scenario and a present day (control) scenario. S ymbiodinium population density in the sponge tissue was the highest under the pre‐industrial scenario, and decreased towards the two future scenarios with sponge replicates under the ‘business‐as‐usual’ CO 2 emission scenario exhibiting strong bleaching. Despite these changes, biomass production and the ability of the sponge to erode coral carbonate materials both increased under the future scenarios. Our study suggests that C. orientalis will likely grow faster and have higher bioerosion rates in a high CO 2 future than at present, even with significant bleaching. Assuming that our findings hold for excavating sponges in general, increased sponge biomass coupled with accelerated bioerosion may push coral reefs towards net erosion and negative carbonate budgets in the future.10aAcidification10aAtmospheric carbon dioxide10abioerosion10acarbon dioxide10aChemical oceanography10aClimate change10acoral reefs10aGlobal temperature changes10aGlobal warming10ainvertebrates10aOcean10aOcean temperature10aReefs10aSponges10aStatistics10atemperature1 aFang, James, K. H.1 aMello‐Athayde, Matheus, A.1 aSchönberg, Christine, H. L.1 aKline, David, I.1 aHoegh‐Guldberg, Ove1 aDove, Sophie  uhttps://reefichno.myspecies.info/content/sponge-biomass-and-bioerosion-rates-increase-under-ocean-warming-and-acidification03074nas a2200325   4500008004100000020001400041245009200055210006900147260004600216300001400262490000700276520205900283653001802342653001502360653001902375653000902394653001102403653000902414653002202423653001902445653001102464653001202475653001602487100002302503700003302526700003102559700002402590700001702614856011702631       2014                        eng d  a1354-101300aEffects of ocean warming and acidification on the energy budget of an excavating sponge0 aEffects of ocean warming and acidification on the energy budget   aEnglandbWiley Subscription Services, Inc  a1043-10540 v203 aRecent research efforts have demonstrated increased bioerosion rates under experimentally elevated partial pressures of seawater carbon dioxide (pCO2 ) with or without increased temperatures, which may lead to net erosion on coral reefs in the future. However, this conclusion clearly depends on the ability of the investigated bioeroding organisms to survive and grow in the warmer and more acidic future environments, which remains unexplored. The excavating sponge Cliona orientalis Thiele, is a widely distributed bioeroding organism and symbiotic with dinoflagellates of the genus Symbiodinium. Using C. orientalis, an energy budget model was developed to calculate amounts of carbon directed into metabolic maintenance and growth. This model was tested under a range of CO2 emission scenarios (temperature + pCO2 ) appropriate to an Austral early summer. Under a pre-industrial scenario, present day (control) scenario, or B1 future scenario (associated with reducing the rate of CO2 emissions over the next few decades), C. orientalis maintained a positive energy budget, where metabolic demand was likely satisfied by autotrophic carbon provided by Symbiodinium and heterotrophic carbon via filter-feeding, suggesting sustainability. Under B1, C. orientalis likely benefited by a greater supply of photosynthetic products from its symbionts, which increased by up to 56% per unit area, and displayed an improved condition with up to 52% increased surplus carbon available for growth. Under an A1FI future scenario (associated with 'business-as-usual' CO2 emissions) bleached C. orientalis experienced the highest metabolic demand, but carbon acquired was insufficient to maintain the sponge, as indicated by a negative energy budget. These metabolic considerations suggest that previous observations of increased bioerosion under A1FI by C. orientalis may not last through the height of future A1FI summers, and survival of individual sponges may be dependent on the energy reserves (biomass) they have accumulated through the rest of the year.10aAcidification10abioerosion10acarbon balance10aCHAR10aCorals10aCZAR10aEnergy efficiency10aGlobal warming10aOceans10aSponges10atemperature1 aFang, James, K. H.1 aSchönberg, Christine, H. L.1 aMello-Athayde, Matheus, A.1 aHoegh-Guldberg, Ove1 aDove, Sophie  uhttps://reefichno.myspecies.info/content/effects-ocean-warming-and-acidification-energy-budget-excavating-sponge