ALBERT

Description: Micro-Raman spectroscopy has been used on adult bivalve shells to investigate organic and inorganic shell components but has not yet been applied to bivalve larvae. It is known that the organic matrix of larval shells contains pigments, but less is known about the presence or source of these molecules in larvae. We investigated Raman spectra of seven species of bivalve larvae to assess the types of pigments present in shells of each species and how the ratio of inorganic : organic material changes in a dorso-ventral direction. In laboratory experiments, we reared larvae of three clam species in waters containing different organic signatures to determine if larvae incorporated compounds from source waters into their shells. We found differences in spectra and pigments between most species but found less intraspecific differences. A neural network classifier for Raman spectra classified five out of seven species with greater than 85% accuracy. There were slight differences between the amount and type of pigment present along the shell, with the prodissoconch I and shell margin areas being the most variable. Raman spectra of 1-day-old larvae were found to be differentiable when larvae were reared in waters with different organic signatures. With micro-Raman spectroscopy, it may be possible to identify some unknown species in the wild and trace their natal origins, which could enhance identification accuracy of bivalve larvae and ultimately aid management and restoration efforts.

Description: Tephra provides regional chronostratigraphical marker horizons that can link different climate archives with highly needed accuracy and precision. The results presented in this work exemplify, however, that the intermittent storage of tephra in ice sheets and during its subsequent iceberg transport, especially during glacial stages, constitutes a potential source of serious error for the application of tephrochronology to Nordic Seas and North Atlantic sediment archives. The peak shard concentration of the rhyolitic component of the North Atlantic Ash Zone II (NAAZ-II) tephra complex, often used to correlate marine and ice core records in Marine Isotope Stage (MIS) 3, is shown to lag the eruption event by ca. 100–400 years in some North Atlantic and Norwegian Sea cores. While still allowing for a correlation of archives on millennial timescales, this time delay in deposition is a major obstacle when addressing the lead–lag relationship on short timescales (years to centuries). A precise and accurate determination of lead–lag relationships between archives recording different parts of the climate system is crucial in order to test hypotheses about the processes leading to abrupt climate change and to evaluate results from climate models. Copyright # 2011 John Wiley & Sons, Ltd.

Description: Growth rates of the cold-water corals (CWC) Madrepora oculata, Lophelia pertusa, Desmophyllum dianthus and Dendrophyllia cornigera were measured over 8 mo under controlled conditions (12°C in the dark, fed 5 times a week) by means of the buoyant weight technique. Additionally, linear growth rates were measured in M. oculata and L. pertusa for 2 and 1 yr, respectively. The weight measurements revealed growth rates, expressed as percent growth per day (mean ± SD), of 0.11 ± 0.04 for M. oculata, 0.02 ± 0.01 for L. pertusa, 0.06 ± 0.03 for D. dianthus and 0.04 ± 0.02 % d–1 for D. cornigera. Growth in M. oculata was significantly higher (p 〈 0.0001) than in the other 3 CWC species. For M. oculata and L. pertusa, also linear growth was recorded. These values (mean ± SD) were 0.014 ± 0.007 and 0.024 ± 0.018 mm d–1 for M. oculata and L. pertusa, respectively. This is the first study that compares the growth rates of 4 different CWC species under the same experimental conditions of water flow, temperature, salinity and food supply. These corals have different growth rates, both in terms of total weight increase and linear increase, and these growth rates can be related to interspecific physiological differences. Data on growth rates are essential to understand the population dynamics of CWC as well as the recovery capacity of these communities after disturbance.

Description: A total of 96 species of sponge were recorded in a bathymetric survey conducted within the iSimangaliso Wetland Park. Non-random processes are hypothesised to account for the decline in species richness with increasing depth, and the data add support to Rapoport’s rule. Morphological and colour diversity were strongly correlated and decreased with depth. Five communities could be identified at the 30% level of similarity using cluster analysis, and these correspond to intertidal and shallow subtidal (to 10 m), deep sub-photic zone (coral reefs: 10–30 m), deep reefs (40–90 m), canyon margin (100–140 m) and canyon (140–360 m). The data add support to recently hypothesised bathymetric zones around South Africa.

Description: Mucus, a complex composed primarily of carbohydrates, is released in similar quantities by scleractinian warm- and cold-water reef corals, and can function as an important carrier of organic material from corals to a range of consumers, microbes in particular. However, information about mucus chemical composition is rare for warm-water corals and non-existent for cold-water corals. This study therefore presents comparative carbohydrate composition analyses of mucus released by the dominant and cosmopolitan warm- and cold-water coral genera. Arabinose was the major mucus carbohydrate component for the genus Acropora, but was not found in cold-water coral mucus. Mucus derived from corals of the genus Fungia contained significantly more fucose than the mucus of all other coral genera. However, comparison of mucus carbohydrate composition for the warm- and cold-water corals in the present study and in the literature revealed no significant differences. This indicates use of similar carbohydrate components (with the exception of arabinose) during mucus synthesis by scleractinian corals, largely irrespective of zooxanthellate or azooxanthellate carbon supply mechanisms.

Description: Cold-water coral (CWC) reefs constitute one of the most complex deep-sea habitats harboring a vast diversity of associated species. Like other tropical or temperate framework builders, these systems are facing an uncertain future due to several threats, such as global warming and ocean acidification. In the case of Mediterranean CWC communities, the effect may be exacerbated due to the greater capacity of these waters to absorb atmospheric CO2 compared to the global ocean. Calcification in these organisms is an energy-demanding process, and it is expected that energy requirements will be greater as seawater pH and the availability of carbonate ions decrease. Therefore, studies assessing the effect of a pH decrease in skeletal growth, and metabolic balance are critical to fully understand the potential responses of these organisms under a changing scenario. In this context, the present work aims to investigate the medium- to long-term effect of a low pH scenario on calcification and the biochemical composition of two CWCs from the Mediterranean, Dendrophyllia cornigera and Desmophyllum dianthus. After 314 d of exposure to acidified conditions, a significant decrease of 70 % was observed in Desmophyllum dianthus skeletal growth rate, while Dendrophyllia cornigera showed no differences between treatments. Instead, only subtle differences between treatments were observed in the organic matter amount, lipid content, skeletal microdensity, or porosity in both species, although due to the high variability of the results, these differences were not statistically significant. Our results also confirmed a heterogeneous effect of low pH on the skeletal growth rate of the organisms depending on their initial weight, suggesting that those specimens with high calcification rates may be the most susceptible to the negative effects of acidification.

Description: In the Mediterranean deep-sea, scleractinian cold-water corals (CWC) are observed to survive at the uppermost end of their presumed thermal distribution range (4–13 °C). Here, we show that 2 common CWC species (i.e. Dendrophyllia cornigera and Desmophyllum dianthus) maintained in aquaria can indeed tolerate considerably elevated seawater temperatures (17.5 ± 0.1 °C), while growing at similar (D. dianthus) or significantly higher (D. cornigera) rates than conspecifics cultured in parallel for 87 days at ambient Mediterranean deep-sea temperature (12.5 ± 0.1 °C). Neither differences in coral appearance nor mortality were evident for both species at either temperature. D. dianthus grew significantly faster (0.23 ± 0.08 % day−1) than D. cornigera (0.05 ± 0.01 % day−1) under ambient thermal conditions. Growth of D. cornigera increased significantly (0.14 ± 0.07 % day−1) at elevated temperature, while Desmophyllum dianthus growth showed no significant difference under both conditions. These findings suggest that D. dianthus and D. cornigera may be capable of surviving in warmer environments than previously reported, and thus challenge temperature as the paramount limiting environmental factor for the occurrence of some CWC species.

Description: INTRODUCTION: Lichens are self-sustaining partnerships comprising fungi as shape-forming partners for their enclosed symbiotic algae. They produce a tremendous diversity of metabolites (1050 metabolites described so far). OBJECTIVES: A comparison of metabolic profiles in nine lichen species belonging to three genera (Lichina, Collema and Roccella) by using an optimised extraction protocol, determination of the fragmentation pathway and the in situ localisation for major compounds in Roccella species. METHODS: Chemical analysis was performed using a complementary study combining a Taguchi experimental design with qualitative analysis by high-performance liquid chromatography coupled with mass spectrometry techniques. RESULTS: Optimal conditions to obtain the best total extraction yield were determined as follows: mortar grinding to a fine powder, two successive extractions, solid:liquid ratio (2:60) and 700 rpm stirring. Qualitative analysis of the metabolite profiling of these nine species extracted with the optimised method was corroborated using MS and MS/MS approaches. Nine main compounds were identified: 1 β-orcinol, 2 orsellinic acid, 3 putative choline sulphate, 4 roccellic acid, 5 montagnetol, 6 lecanoric acid, 7 erythrin, 8 lepraric acid and 9 acetylportentol, and several other compounds were reported. Identification was performed using the m/z ratio, fragmentation pathway and/or after isolation by NMR analysis. The variation of the metabolite profile in differently organised parts of two Roccella species suggests a specific role of major compounds in developmental stages of this symbiotic association. CONCLUSION: Metabolic profiles represent specific chemical species and depend on the extraction conditions, the kind of the photobiont partner and the in situ localisation of major compounds.

Description: Uraninite solubility in 0.001–2.0 m HCl solutions was experimentally studied at 500°C, 1000 bar, and hydrogen fugacity corresponding to the Ni/NiO buffer. It was shown that the following U(IV) species dominate in the aqueous solution: U(OH)40, U(OH)2Cl20, and UOH Cl30 Using the results of uraninite solubility measurement, the Gibbs free energies of U(IV) species at 500°C and 1000 bar were calculated (kJ/mol): −9865.55 for UO2(aq), −1374.57 for U(OH)2 Cl20, and −1265.49 for UOH Cl30, and the equilibrium constants of uraninite dissolution in water and aqueous HCl solutions were estimated: UO2(cr) = UO2(aq), pK0 = 6.64; UO2(cr) + 2HCl0 = U(OH)2 Cl20, pK2 = 3.56; and UO2(cr) + 3HCl0 = UOHcl30 + H2O, pK3 = 3.05. The value pK1 ≈ 5.0 was obtained as a first approximation for the equilibrium UO2(cr) + H2O + HCl0 = U(OH)3Cl0. The constant of the reaction UO2(cr) + 4HCl0 = UCl40 + 2H2O (pK4 = 7.02) was calculated taking into account the ionization constants of U Cl40 and U(OH)40, obtained by extrapolation from 25 to 500°C at 1000 bar using the BR model. Intense dissolution and redeposition of gold (material of experimental capsules) was observed in our experiments. The analysis and modeling of this phenomenon suggested that the UO2 + x/UO2 redox pair oxidized Au(cr) to Au+(aq), which was then reduced under the influence of stronger reducers.

Description: Uncertainty over the identity and age of Toba tephras across peninsular India persists, with radiometric age dates contradicting earlier compositional data, which have been used to identify this important Stratigraphie marker as the Youngest Toba Tuff (YTT). To address this issue, new single glass shard analyses have been performed for samples from Morgaon and Bori (north-western India), which have recently been dated at c. 800 ka. These, and indeed all Toba tephra samples thus far analysed from India, show the presence of four populations of glass shards (defined by their Ba/Y ratio), which uniquely identifies them as products of the c. 75-ka Youngest Toba eruption. Confirmation that the YTT fingerprint is characteristic comes from new analyses of Oldest Toba Tuff (OTT) glass shards from five sites in the Indian Ocean. These are compositionally identical to Layer D from the ODP site 758 Sediment core (c. 800 ka), and belong to a single, low-Ba population, clearly different from YTT. These analyses show that there is essentially no reworked OTT material in the YTT eruption, and indicate unequivocally that all known Toba tephra occurrences in India belong to the c. 75-ka Youngest Toba eruption.