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Corals exert a strong biological control over their calcification processes, but there is a lack of knowledge on their capability of long-term acclimatization to ocean acidification (OA). We used a dual geochemical proxy approach to estimate the calcifying fluid pH (pHcf) and carbonate chemistry of a Mediterranean coral (Balanophyllia europaea) naturally growing along a pH gradient (range: pHTS 8.07–7.74). The pHcf derived from skeletal boron isotopic composition (δ11B) was 0.3–0.6 units above seawater values and homogeneous along the gradient (mean ± SEM: Site 1 = 8.39 ± 0.03, Site 2 = 8.34 ± 0.03, Site 3 = 8.34 ± 0.02). Also carbonate ion concentration derived from B/Ca was homogeneous [mean ± SEM (μmol kg–1): Site 1 = 579 ± 34, Site 2 = 541 ± 27, Site 3 = 568 ± 30] regardless of seawater pH. Furthermore, gross calcification rate (GCR, mass of CaCO3 deposited on the skeletal unit area per unit of time), estimated by a “bio-inorganic model” (IpHRAC), was homogeneous with decreasing pH. The homogeneous GCR, internal pH and carbonate chemistry confirm that the features of the “building blocks” – the fundamental structural components – produced by the biomineralization process were substantially unaffected by increased acidification. Furthermore, the pH up-regulation observed in this study could potentially explain the previous hypothesis that less “building blocks” are produced with increasing acidification ultimately leading to increased skeletal porosity and to reduced net calcification rate computed by including the total volume of the pore space. In fact, assuming that the available energy at the three sites is the same, this energy at the low pH sites could be partitioned among fewer calicoblastic cells that consume more energy given the larger difference between external and internal pH compared to the control, leading to the production of less building blocks (i.e., formation of pores inside the skeleton structure, determining increased porosity). However, we cannot exclude that also dissolution may play a role in increasing porosity. Thus, the ability of scleractinian corals to maintain elevated pHcf relative to ambient seawater might not always be sufficient to counteract declines in net calcification under OA scenarios.

The impacts of artificial light at night (ALAN) on marine ecosystems have emerged as a focus for ecological light pollution research in recent years, yet the global prevalence of ALAN in underwater marine ecosystems is unknown. We have derived a global atlas of ALAN throughout the marine water column that will accelerate our understanding of its sources and environmental impacts. At a depth of 1 m, 1.9 million km2 of the world’s coastal seas are exposed to biologically important ALAN, which equates to around 3.1% of the global exclusive economic zones. This area decreases to 1.6 million km2 (2.7%) at a depth of 10 m, and to 840,000 km2 (1.4%) at 20 m. The most heavily exposed regions are those that experience intensive offshore development in addition to coastal urbanization. The atlas highlights that ALAN as a global change issue is not exclusive to land but is also widespread in the world’s underwater habitats at irradiances that elicit biological responses in marine organisms.

Corals exert a strong biological control over their calcification processes, but there is a lack of knowledgeon their capability of long-term acclimatization to ocean acidification (OA). We used a dual geochemicalproxy approach to estimate the calcifying fluid pH (pHcf) and carbonate chemistry of a Mediterranean coral(Balanophyllia europaea) naturally growing along a pH gradient. The pHcf derived from skeletal boronisotopic composition (11B) was homogeneous along the gradient, exhibiting an increased up-regulationcapability with increasing acidification. Also, carbonate ion concentration derived from B/Ca washomogeneous regardless of seawater pH. Furthermore, gross calcification rate (GCR), estimated by a “bio-inorganic model” (IpHRAC), was homogeneous with decreasing pH. This determined an apparentlyunresolved puzzle with the previously observed decrease in net calcification rates on the same specimensalong this gradient. However, on the contrary, the homogeneous GCR was in agreement with the previousresults in which the ‘building blocks’ produced by the biomineralization process were substantiallyunaffected by increased acidification. Furthermore, the pH up-regulation observed in this study provides asubstantial contribution in solving the puzzle. In fact, it confirms the previous hypothesis that less buildingblocks are produced with increasing acidification by showing thatB. europaea likely produces less buildingblocks because part of its energy is used to maintain elevated calcifying fluid pH with increasing acidity.Thus, the ability of scleractinian corals to maintain elevated pHcf relative to ambient seawater might notalways be sufficient to counteract declines in net calcification under ocean acidification scenarios.

This volume presents a broad panorama of the current status of research of invertebrate animals considered belonging to the phylum Cnidaria, such as hydra, jellyfish, sea anemone, and coral. In this book the Cnidarians are traced from the Earth's primordial oceans, to their response to the warming and acidifying oceans. Due to the role of corals in the carbon and calcium cycles, various aspects of cnidarian calcification are discussed. The relation of the Cnidaria with Mankind is approached, in accordance with the Editors' philosophy of bridging the artificial schism between science, arts and Humanities. Cnidarians' encounters with humans result in a broad spectrum of medical emergencies that are reviewed. The final section of the volume is devoted to the role of Hydra and Medusa in mythology and art.

OCEAN WARMING AND ACIDIFICATION SYNERGISTICALLY INCREASE CORAL MORTALITY CO2-driven ocean warming (OW) and acidification (OA) has prompted urgent research to assess their potential effects on the marine environment, with strong emphasis on calcifying organisms. To correctly predict how these stressors will affect marine organisms, their synergistic effects must be assessed. Here we investigate the interactive effects of OW and OA on the mortality and growth of three Mediterranean coral species: the solitary zooxanthellate Balanophyllia europaea, the solitary non-zooxanthellate Leptopsammia pruvoti and the colonial non-zooxanthellate Astroides calycularis. Corals were transplanted, in different seasons, in proximity to a volcanic CO2 vent where water is naturally acidified to levels matching future IPCC scenarios. We show a strong synergistic adverse effect on mortality rates of the three species. Net calcification rates of the zooxanthellate species were not affected by reduced pH, while those of the two non-zooxanthellate species were negatively affected, indicating that different levels of resilience/resistance to OW and OA among species in symbiosis with photosynthetic algae or asymbiotic ones may be related to different modes of nutrition and/or biomineralization processes. Natural CO2-leaking marine sites can provide essential information on the combined effects of OA and OW on Mediterranean scleractinian corals, which may help understand to which extent different corals will be threatened by increasing atmospheric CO2 pollution.

Ocean acidification is expected to significantly affect calcifying marine organisms, such as corals. While ocean acidification effects on coral calcification have been widely investigated, the effects on coral gametogenesis are almost unknown. A volcanic vent at Panarea Island (Mediterranean Sea, Italy) characterized by continuous and localized CO2 emission, generates a stable pCO2 gradient from the centre to its periphery, providing a unique natural laboratory for ocean acidification studies. Here we assessed the effects of ocean acidification on gametogenesis and embryogenesis of the Mediterranean non-zooxanthellate coral Leptopsammia pruvoti transplanted along this natural pCO2 gradient. After 3 months under experimental conditions, increasing pCO2 seemed to negatively influence spermary production and development. In the control Site, all spermaries showed the latest (most advanced) maturation stage while in the most acidic Sites they also displayed earlier stages, indicating a delay in spermatogenesis and consequently of fertilization and planulation processes. Considering the negative response showed by this species after a short-term exposure, an even stronger negative effect on sexual reproduction is hypothesized under a long-term exposure.

Increasing research effort on marine calcifying organisms is important and urgent, given the projected CO2-driven ocean acidification for the coming century. Here we assess the growth and population dynamics of the Mediterranean endemic zooxanthellate solitary coral B. europaea at three sites along a natural pCO2 gradient of the volcanic vents off Panarea Island (Italy), in the Mediterranean Sea. B. europaea was the only scleractinian found along the gradient and its abundance decreased with increasing pCO2. The age-length relationships, obtained for each site by sclerochronology through computerized tomography, resulted homogeneous and then data were pooled to obtain a general age-length relationship. Skeletal linear extension rate and bulk skeletal density were measured and net calcification rate was calculated for each sample at each site. While linear extension rate did not vary with pCO2, bulk skeletal density and net calcification rate decreased with increasing pCO2. The population age structure was obtained by analyzing photoquadrats and several observed and theoretical demographic parameters were derived (age structure stability, instantaneous rate of mortality, average age, % of immature individuals, age at maximum biomass, average age of biomass) and compared among sites. Populations showed a deficiency of young individuals with increasing pCO2. The species seems sensitive to ocean acidification even if the photosynthetic efficiency of its symbionts increases with pCO2, suggesting an even higher sensitivity for shallow water non-zooxanthellate scleractinians.

In the present volume, we exhibit a broad panorama of the current status of cnidarian research. On the timescale, the cnidarians are traced from the earliest geological records of their place at the very cradle of the evolution of multicellular organisms in the Earth’s primordial oceans, to their response to present climate change effects in the warming and acidifying oceans. The latter aspects are described on the molecular and physiological responses followed by resulting population level effects. Their evolution is accompanied by their taxonomic diversification and geographic expansion, including their present role among invasive species. Their acquisition of neural networks and development of skeletal elements are described on the background of the evolutionary history of these systems covering both evolutionary and ontogenetic analyses. The uniquely widespread and intimate mutualistic symbiotic associations with algae is described in taxa, such as jellyfishes and corals, revealing the roots of the dependence of so many cnidarian species on photosynthesis. That allows their symbiotic algae – the zooxanthel- lae – to provide most of the metabolic energy needs of the animal algae holobiont. Due to the dominant role of corals in the biogeochemical carbon and calcium cycles, the various aspects of cnidarian calcification are discussed in terms of accepted theories while exposing their difficulties. The relation of the Cnidaria with mankind is approached on several levels, in accordance with the editors’ philosophy of bridging the artificial schism between science, arts and humani- ties. On the direct level, the various encounters with humans result in a broad spectrum of medical emergencies of varying seriousness are reviewed. On a more detached level, humans from the very emergence of our species were fascinated by corals, and various coralline orna- mental objects are found in burial sites in coastal regions in all continents. Chapters are dedi- cated to the history of coral harvesting down to current sustainable culture practices. To the role of “Hydra” and “Medusa” in mythology, art and culture is devoted in the final section of the volume. That section closes the unique, topical, multi-level, interdisciplinary coverage of the wide- spread, predominantly marine taxon, the Cnidaria. The present volume takes the reader through the earliest evolution of the taxon and the ramification of its diversity. It proceeds to the group’s molecular and genomic make-up, through its ecology and physiology, all the way to its use in jewellery and invasion of human imagination in art and myth. Bologna, Italy Stefano Goffredo Ramat-Gan, Israel Zvy Dubinsky

Environmental change relations in the Mediterranean Sea since its formation and all aspects of life in it and around its shores Looks at ways the geology, currents and chemistry of the Sea have affected plant life, fauna and mankind from the distant past, through present patterns, towards likely future scenarios Essential to researchers and advanced students focusing on the Mediterranean environment, biota, past, heritage and challenges laying ahead for its diverse dependents​ This volume is an indispensable addition to the multidisciplinary coverage of the science of the Mediterranean Sea. The editors have gathered leading authorities from the fields of Marine Biology, Ecology, paleoclimatology, Chemical and Physical Oceanography, Zoology, Botany, Aquatic Photosynthesis, Socioeconomics, Mariculture, Mediterranean History and Science of Humanity. Beginning with the birth of the Mediterranean Sea and its myths. From coral to fish, an introduction is given to its major inhabitants of plants and animals past and present. The chapters illustrate how organisms interact as part of the structure and function of the Sea's main ecosystems. The rise of the Mediterranean as the cradle of the Western Civilization leads to a discourse on the status of human interaction with the sea. Accelerating global climate change, water warming, ocean acidification and sea level rise, and analyses of their effects on key organisms, entire ecosystems and human socioeconomics are given. Forecasting and predictions are presented taking into account different future scenarios from the IPCC (International Panel on Climate Change). The volume is richly illustrated in color, with an extensive bibliography. A valuable addition to the limited literature in the field, offering up-to-date broad coverage merging science and humanities. Content Level » Research Related subjects » Aquatic Sciences - Ecology - Environmental / Development / Agricultural Economics

Oceanic uptake of anthropogenic CO2 is causing significant changes in ocean chemistry, reducing pH and increasing sea surface temperature. A decline of 0.3–0.5 pH units and 2.0-4.5 °C of temperature are expected by 2100. Few information are available regarding the effects of ocean acidification on sexual reproduction in corals and none on temperate corals. This study assessed the effects of ocean acidification on sexual reproduction in three Mediterranean scleractinian corals: Balanophyllia europaea (solitary, zooxanthellate), Leptopsammia pruvoti (solitary, azooxanthellate), and Astroides calycularis (colonial, azooxanthellate). The relationship between reproductive parameters (fecundity rate, spermary abundance, gonadal index, reproductive element size) and pCO2 were assessed at an underwater volcanic crater characterized by continuous emissions of CO2 which create a natural pH gradient, located near the island of Panarea (Tyrrhenian Sea, Italy). Samples of the three species were transplanted along the pH gradient in four sites from the center of crater (pH 7.4) to its periphery (control). The biological responses were analyzed according to different reproductive (gonochoric vs hermaphrodite) and metabolic (zooxanthellate vs non zooxanthellate) strategies of each species.

ncreasing research effort on marine calcifying organisms is important and urgent, given the projected CO2-driven ocean acidification for the coming century. Here we assess the growth and population dynamics of the Mediterranean endemic zooxanthellate solitary coral Balanophyllia europaea at three sites along a natural pCO2 gradient of the volcanic vents off Panarea Island (Italy). B. europaea was the only scleractinian found along the gradient. The age-length relationships obtained for each site by dating corals by means of computerized tomography resulted homogeneous, then a general age-length relationship was calculated. Growth parameters (linear extension rate, bulk skeletal density, and net calcification rate) were obtained for each site. While linear extension rate did not vary with pCO2, bulk skeletal density and net calcification rate decreased with increasing pCO2. At each site, the age structure was obtained, and several observed and theoretical demographic parameters were derived (age structure stability, istantaneous rate of mortality, average age, % of immature individuals, age at maximum biomass, average age of biomass) and compared among sites. The results are discussed in relation to the envisaged ocean acidification scenarios

Correlations between solar radiation, sea surface temperature (SST), biometry, and population density were assessed along a wide latitudinal gradient in the non-zooxanthellate solitary coral Caryophyllia inornata. Biometric parameters were more strongly correlated with temperature than with solar radiation as in previous studies on Mediterranean solitary corals. With increasing SST, populations were characterized by bigger polyps, and consequently by a higher percent area coverage and mass per square meter. Population abundance was not correlated with SST, similarly to the non-zooxanthellate solitary Leptopsammia pruvoti. Instead, the population density of the zooxanthellate solitary Balanophyllia europaea decreases with increasing SST. When extrapolating the relationships between biological parameters of the three species and SST, according to the projected seawater temperature increase, a higher tolerance to temperature for non-zooxanthellate species seems to be confirmed

Global climate change is predicted to affect marine organisms and ecosystems reliant on the accumulation of calcium carbonate structures, as coral reefs, potentially reducing the socioeconomic benefits these habitats provide. In the marine realm, two of the main stressors causing significant changes are ocean warming and ocean acidification. Projections of future climatic change estimate a 0.6-2.0°C average increase in surface ocean temperature by the end of 2100, posing a major threat for marine organisms. In temperate areas, the effect of warming is expected to be even greater. The Mediterranean Sea is already showing warming rates three times higher than the global ocean. Increased seawater temperature in the Mediterranean Sea has determined longer stratification periods associated with mass mortality events. The first well-documented Mediterranean multispecies mass mortality events were during the summers 1999 and 2003. In both years, a positive correlation was observed between mortality rates and exposure to heat stress, indicating that shallow water corals are living, at least in the North Mediterranean, near their upper thermal limits during summer. Since the frequency of abnormally warm summers is expected to increase in the next century, as a result of climate change, such mortality events in summer may also become more frequent as a direct response to elevated temperatures. Also ocean acidification is a global phenomenon which impact varies locally. The Mediterranean Sea has experienced a pH decrease of up to 0.14 units since the pre-industrial era, larger than the global average surface ocean pH decrease. Hence, understanding how enhanced acidity has already affected and how it will likely affect Mediterranean Sea ecosystems and their key taxa is urgent and crucial. Given the projected decrease of seawater pH, the mass mortality events could be exacerbated by the combination of high temperatures and low pH. Studies like this one, assessing the synergistic interaction between low pH and elevated temperatures, are essential to detect possible interactions between multiple stressors and establish to which extent corals inhabiting shallower ranges will be threatened by climate change. Here we assessed the combined effects of in situ exposure to different acidity and seasonal temperatures on the mortality and growth rates of three Mediterranean scleractinian corals; the solitary zooxanthellate Balanophyllia europaea, the solitary azooxanthellate Leptopsammia pruvoti and the colonial azooxanthellate Astroides calycularis. The corals were transplanted and observed in different seasonal conditions in proximity to a volcanic vent where water is naturally acidified to levels matching different future Intergovernmental Panel on Climate Change scenarios. The results suggest differential synergistic adverse effects of increased sea temperature and acidity and different levels of resilience/resistance to climate change among temperate coral species, probably related to different modes of nutrition and/or biomineralization processes, making symbiotic species relatively less sensitive due to the increased photosynthesis at high CO2. Acknowledgements: The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (F P7/2007-2013)/ERC grant agreement n° 249930 – CoralWarm: Corals and global warming: the Mediterranean versus the Red Sea.

In the framework of the European Project CoralWarm [1,2], the pore-volume structure of the skeletons of scleractinian corals from Mediterranean Sea have been analyzed with the aim to determine parameters from NMR Relaxometry useful to relate porosity and pore-size distribution to environmental conditions. The final goal is to relate structure variations to climate change. Mercury intrusion porosimetry shows wide ranges of pore radius, but the high Hg pressure could cause particle compression and rupture. The definition of a method to determine porosity and pore-size distribution in a non-invasive, non-destructive way can be of great interest. In a recent paper [3] we have demonstrated that NMR Relaxometry of clean coral skeletons, saturated with water, is an efficient tool for pore-volume structure characterization. The data obtained from CPMG sequence were inverted by UpenWin software [4] to get T2 distributions. Parametric and non-parametric statistical test have been performed on two parameters extracted from T2 distributions: the cut-off time (relaxation time in between two peaks, or the tail and the peak) and the micro-porosity (fraction of signal with relaxation times below the cut-off). Also, a multivariate analysis has been performed to check the sensitivity of microporosity to variations of mass and growing temperature. The results demonstrate that the NMR parameters so determined are good tools to check the sensitivity of the corals to the environmental changes. Acknowledgements: the research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement n° 249930 –CoralWarm: Corals and global warming: the Mediterranean versus the Red Sea; the authors wish to thank the CoralWarm team members for corals sampling and cleaning. [1] ERC, IDEAS Project CoralWarm - Corals and global warming: the Mediterranean versus the Red Sea, http://www. coralwarm.eu.; [2] E. Caroselli et al., Zoology, 114, 255-264 (2011); [3] P. Fantazzini et al., Environmental Science & Technology, in press, DOI:10.1021/es402521b; [4] UpenWin, a software to invert multi-exponential data, commercialized by the University of Bologna, www.unibo.it/Portale/Servizi+ImpreseUpenWin.htm.

The predicted CO2-driven ocean acidification (OA) of the coming century has prompted urgent research to assess its potential effects on the marine environment, with strong emphasis on calcifying organisms. Here we assessed the effects of in situ exposure to different pH conditions on the mortality and growth of three Mediterranean scleractinian corals: the solitary zooxanthellate Balanophyllia europaea, the solitary non-zooxanthellate Leptopsammia pruvoti and the colonial non-zooxanthellate Astroides calycularis. The corals were transplanted in proximity to a volcanic CO2 vent where water is naturally acidified to levels matching future IPCC scenarios. In all three species, mortality at reduced pH was exacerbated when seawater temperatures peaked in summer. Growth rates of the zooxanthellate species did not react to reduced pH, while those of the two non-zooxanthellate species were negatively affected, indicating that zooxanthellate species may be more resistant in a high CO2 world. Natural CO2-leaking marine sites can provide essential information on the combined effects of OA and global warming on Mediterranean scleractinian corals, which may help understand to which extent different corals will be threatened by increasing atmospheric CO2 pollution.

Calcification can be viewed as an emergent behavior resulting from a complex system in which several sub-processes on very different temporal and spatial scales (ranging from nanometer and nanoseconds to meters and years) are connected in a multiscale system. Sub-processes like gene regulation, organic molecules influencing the mineral deposition process, cellular and physiological processes and environment are all linked. Although different calcification mechanisms and pathways have been proposed, there is still no conclusive and comprehensive model of the process. In recent years, many efforts have been made to individually elucidate the regulatory subprocesses. It is important to integrate this knowledge into a multiscale model and analysis that will increase fundamental understanding, guide coral preservation efforts and find potentially important applications in material sciences. Computational models can effectively aid in this integration, by providing structure and serving as a tool for inferring and interpreting interactions and hypotheses. The multiple data that have been collected and the computational models that have been and could be developed will be reviewed, starting with the coral transcriptome, followed by the skeletal proteome, tissue physiology, and skeletal micro- and macromorphology.