Biochemical Trade-Offs: Evidence for Ecologically Linked Secondary Metabolism of the Sponge Oscarella balibaloi

Secondary metabolite production is assumed to be costly and therefore the resource allocation to their production should be optimized with respect to primary biological functions such as growth or reproduction. Sponges are known to produce a great diversity of secondary metabolites with powerful biological activities that may explain their domination in some hard substrate communities both in terms of diversity and biomass. Oscarella balibaloi (Homoscleromorpha) is a recently described, highly dynamic species, which often overgrows other sessile marine invertebrates. Bioactivity measurements (standardized Microtox assay) and metabolic fingerprints were used as indicators of the baseline variations of the O. balibaloi secondary metabolism, and related to the sponge reproductive effort over two years. The bioactivity showed a significant seasonal variation with the lowest values at the end of spring and in early summer followed by the highest bioactivity in the late summer and autumn. An effect of the seawater temperature was detected, with a significantly higher bioactivity in warm conditions. There was also a tendency of a higher bioactivity when O. balibaloi was found overgrowing other sponge species. Metabolic fingerprints revealed the existence of three principal metabolic phenotypes: phenotype 1 exhibited by a majority of low bioactive, female individuals, whereas phenotypes 2 and 3 correspond to a majority of highly bioactive, non-reproductive individuals. The bioactivity was negatively correlated to the reproductive effort, minimal bioactivities coinciding with the period of embryogenesis and larval development. Our results fit the Optimal Defense Theory with an investment in the reproduction mainly shaping the secondary metabolism variability, and a less pronounced influence of other biotic (species interaction) and abiotic (temperature) factors

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

LATE AND POSTGLACIAL PALEOENVIRONMENTS OF THE GULF OF ST-LAWRENCE - MARINE AND TERRESTRIAL PALYNOLOGICAL EVIDENCE

International audienceCored sediments from Anticosti and Esquiman channels and from Cabot Strait have been analyzed for their palynological content, which includes pollen and spores and dinoflagellate cysts. The dinoflagellate cyst assemblages led to the establishment of a regional ecostratigraphy and to quantitative reconstruction of changes in sea-surface conditions using transfer function (best analogue method). Prior to about 10,000 BP, assemblages dominated by Brigantedinium are associated with relatively cold (4-10-degrees-C in August) surface water and extensive seasonal sea-ice cover (up to 8 months/yr.); in Cabot Strait low salinity conditions (25-27 parts-per-thousand) were recorded from about 11,800 to 1 0.000 BP as the result of outflow of meltwater discharge from the Laurentide Ice Sheet. Between ca. 11,000 and 10,500 BP a cooling phase in surface water probably corresponds to the Younger Dryas event. At about 1 0,000 BP, a sharp transition marked by the occurrence of abundant Gonyaulacales, corresponds to the establishment of conditions similar to the present with summer temperatures up to 16-degrees-C, salinity of approximately 31 parts-per-thousand and a seasonal extent of sea-ice of about 2 months/yr. During the Holocene, slight fluctuations of sea-surface temperature are reconstructed, and a thermal optimum is recorded at about 6000 BP. The pollen and spore assemblages led to direct correlations with the onshore palynostratigraphy. In the northern Gulf region, Picea migration apparently rapidly followed the early Holocene surface water warming although the development of dosed coniferous forests occurred much later. In the southern part of the Gulf, the Picea forest expansion coincides with the early Holocene increase of temperature, and the significant occurrence of Tsuga followed the middle Holocene thermal optimum as recorded in sea-surface water

DINOFLAGELLATE CYST DISTRIBUTION IN HIGH-LATITUDE MARINE ENVIRONMENTS AND QUANTITATIVE RECONSTRUCTION OF SEA-SURFACE SALINITY, TEMPERATURE, AND SEASONALITY

International audienceA data base of 179 reference sites documents the relations between the assemblages of organic-walled dinoflagellate cysts and sea-surface temperature, salinity, and seasonality throughout the North Atlantic, adjacent subpolar basins (Labrador Sea, Baffin Bay, Irminger and Iceland basins) and epicontinental environments off eastern Canada (estuary and Gulf of St. Lawrence, Hudson Bay). Principal-component analyses show close relationships between dinoflagellate cyst data and sea-surface conditions: the first component (71.1 % of the variance) correlates with the winter temperature, salinity, and seasonal duration of sea-ice cover, whereas the second component (11.3 % of the variance) appears mainly related to summer temperature. Transfer functions using the best analogue method were tested by reconstructing modern sea-surface conditions on the basis of the reference dinoflagellate cyst assemblages. The correlation coefficient between instrumental averages and reconstructed values ranges from 0.87 (August temperature) to 0.97 (annual duration of sea-ice cover). These transfer functions appear most accurate for the reconstruction of sea-surface conditions in marginal marine environments of high-latitude basins. The only reservation concerns the validity of reconstruction in offshore regions characterized by low productivity where sparse cyst fluxes may result from long-distance transport through currents. The transfer functions that were applied in, as an example, a late Quaternary sequence of the Davis Strait in the northern Labrador Sea, notably suggest seasonal sea-ice cover extent of 6 - 10 months/year and August temperature and salinity of 1-4-degrees-C and 31 - 33 parts per thousand, respectively, during the last glacial optimum (isotopic stage 2)

LATE AND POSTGLACIAL PALEOENVIRONMENTS OF THE GULF OF ST-LAWRENCE - MARINE AND TERRESTRIAL PALYNOLOGICAL EVIDENCE

International audienceCored sediments from Anticosti and Esquiman channels and from Cabot Strait have been analyzed for their palynological content, which includes pollen and spores and dinoflagellate cysts. The dinoflagellate cyst assemblages led to the establishment of a regional ecostratigraphy and to quantitative reconstruction of changes in sea-surface conditions using transfer function (best analogue method). Prior to about 10,000 BP, assemblages dominated by Brigantedinium are associated with relatively cold (4-10-degrees-C in August) surface water and extensive seasonal sea-ice cover (up to 8 months/yr.); in Cabot Strait low salinity conditions (25-27 parts-per-thousand) were recorded from about 11,800 to 1 0.000 BP as the result of outflow of meltwater discharge from the Laurentide Ice Sheet. Between ca. 11,000 and 10,500 BP a cooling phase in surface water probably corresponds to the Younger Dryas event. At about 1 0,000 BP, a sharp transition marked by the occurrence of abundant Gonyaulacales, corresponds to the establishment of conditions similar to the present with summer temperatures up to 16-degrees-C, salinity of approximately 31 parts-per-thousand and a seasonal extent of sea-ice of about 2 months/yr. During the Holocene, slight fluctuations of sea-surface temperature are reconstructed, and a thermal optimum is recorded at about 6000 BP. The pollen and spore assemblages led to direct correlations with the onshore palynostratigraphy. In the northern Gulf region, Picea migration apparently rapidly followed the early Holocene surface water warming although the development of dosed coniferous forests occurred much later. In the southern part of the Gulf, the Picea forest expansion coincides with the early Holocene increase of temperature, and the significant occurrence of Tsuga followed the middle Holocene thermal optimum as recorded in sea-surface water

Synchroneity between marine and terrestrial responses to millennial scale climatic variability during the last glacial period in the Mediterranean region

International audienceLand-sea climatic proxies have been obtained from the Last Glacial section of IMAGES core MD95-2043 (western Mediterranean Sea). Vegetation and alkenone derived SST curves indicate rapid (similar to150 years) and synchronous terrestrial and marine climatic changes, paralleling the Dansgaard-Oeschger (D-O) climatic variability over Greenland. This frequency of climate change can be related to shifts between the two modes of operation of the North Atlantic Oscillation (NAO). Transfer functions applied to the pollen data indicate that there was an amplification of the climatic signal during Heinrich events (HEs) in comparison with other D-O stadials. The development and persistence of both Scandinavian and Atlantic Mobile Polar Highs over southwestern Europe may explain the extreme cooling (similar to10 degreesC) and dryness (400 mm) during Heinrich events 5 and 4 in the Mediterranean region. Comparison of the results of core MD95-2043 with similar climatic data from IMAGES core MD95-2042, located off Portugal, indicates that thermal and precipitation gradients occurred between the Mediterranean and the Atlantic sides of Iberia within HEs. HEs 4 and 5 are associated with more humid conditions in the Atlantic (by 200 mm) than in the Mediterranean site, as is the case at the present time. This comparison also illustrates the different behaviour of these areas during the D-O stadials. In contrast with the Mediterranean site, the Atlantic site shows similar precipitation and temperature drops for all the D-O stadials, including those related to the HEs. Here we propose the operation of different Mobile Polar Highs (MPH) as the driving mechanism for this difference in behaviour between the Atlantic and Mediterranean sides of Iberia. HEs are related to a stronger influence of the Scandinavian MPH, forcing a severe aridification and cooling of the full Iberian Peninsula. The Atlantic MPH may have been dominant during the other stadials, which would preferentially affect Southwestern Iberia