In this volume John Murray investigates the ecological processes that control the distribution, abundance, and species diversity of benthic foraminifera in environments ranging from marsh to the deepest ocean. To interpret the fossil record it is necessary to have an understanding of the ecology of modern foraminifera and the processes operating after death leading to burial and fossilisation. This book presents the ecological background required to explain how fossil forms are used in dating rocks and reconstructing past environmental features including changes of sea level. It demonstrates how living foraminifera can be used to monitor modern-day environmental change. Ecology and Applications of Benthic Foraminifera presents a comprehensive and global coverage of the subject using all the available literature. It is supported by a website hosting a large database of additional ecological information (www.cambridge.org/0521828392) and will form an important reference for academic researchers and graduate students in Earth and Environmental Sciences.

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Ecology and Applications of Benthic Foraminifera

Trabajo presentado en el 39th CIESM Congress, celebrado en Venecia, Italia, del 10 al 14 de mayo de 2010

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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.

This abstract has been translated to other languages (File S1).

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

Studies of deeply buried, sedimentary microbial communities and associated biogeochemical processes during Ocean Drilling Program Leg 201 showed elevated prokaryotic cell numbers in sediment layers where methane is consumed anaerobically at the expense of sulfate. Here, we show that extractable archaeal rRNA, selecting only for active community members in these ecosystems, is dominated by sequences of uncultivated Archaea affiliated with the Marine Benthic Group B and the Miscellaneous Crenarchaeotal Group, whereas known methanotrophic Archaea are not detectable. Carbon flow reconstructions based on stable isotopic compositions of whole archaeal cells, intact archaeal membrane lipids, and other sedimentary carbon pools indicate that these Archaea assimilate sedimentary organic compounds other than methane even though methanotrophy accounts for a major fraction of carbon cycled in these ecosystems. Oxidation of methane by members of Marine Benthic Group B and the Miscellaneous Crenarchaeotal Group without assimilation of methane–carbon provides a plausible explanation. Maintenance energies of these subsurface communities appear to be orders of magnitude lower than minimum values known from laboratory observations, and ecosystem-level carbon budgets suggest that community turnover times are on the order of 100–2,000 years. Our study provides clues about the metabolic functionality of two cosmopolitan groups of uncultured Archaea.

https://www.pnas.org/content/pnas/103/10/3846.full.pdf

Heterotrophic Archaea dominate sedimentary subsurface ecosystems off Peru

Microbial communities in hydrothermally active sediments of the Guaymas Basin (Gulf of California, Mexico) were studied by using 16S rRNA sequencing and carbon isotopic analysis of archaeal and bacterial lipids The Guaymas sediments harbored uncultured euryarchaeota of two distinct phylogenetic lineages within the anaerobic methane oxidation 1 (ANME-1) group, ANME-1a and ANME-1b, and of the ANME-2c lineage within the Methanosarcinales, both previously assigned to the methanotrophic archaea The archaeal lipids in the Guaymas Basin sediments included archaeol, diagnostic for nonthermophilic euryarchaeota, and sn-2-hydroxyarchaeol, with the latter compound being particularly abundant in cultured members of the Methanosarcinales The concentrations of these compounds were among the highest observed so far in studies of methane seep environments The delta-(13)C values of these lipids (delta-(13)C = -89 to -58 per thousand) indicate an origin from anaerobic methanotrophic archaea This molecular-isotopic signature was found not only in samples that yielded predominantly ANME-2 clones but also in samples that yielded exclusively ANME-1 clones ANME-1 archaea therefore remain strong candidates for mediation of the anaerobic oxidation of methane Based on 16S rRNA data, the Guaymas sediments harbor phylogenetically diverse bacterial populations, which show considerable overlap with bacterial populations of geothermal habitats and natural or anthropogenic hydrocarbon-rich sites Consistent with earlier observations, our combined evidence from bacterial phylogeny and molecular-isotopic data indicates an important role of some novel deeply branching bacteria in anaerobic methanotrophy Anaerobic methane oxidation likely represents a significant and widely occurring process in the trophic ecology of methane-rich hydrothermal vents This study stresses a high diversity among communities capable of anaerobic oxidation of methane

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Microbial diversity of hydrothermal sediments in the Guaymas Basin: evidence for anaerobic methanotrophic communities.

Introductory Paper.- Sedimentary Settings on Continental Margins - an Overview.- Continental Margins - Review of Geochemical Settings.- Imaging the Subsurface with 2-D and 3-D Seismic Data.- State of the Art and Future Prospect of Scientific Coring and Drilling of Marine Sediments.- New Technologies for Ocean Margin Studies - Autonomous Instrument Carrier Systems.- Autonomous Underwater Vehicles: Are they the Ideal Sensor Platforms for Ocean Margin Science?.- Margin Building - Regulating Processes.- Physical Processes and Modelling at Ocean Margins.- Seabed Classification at Ocean Margins.- The Benthic Boundary Layer.- Ocean Margin Early Diagenetic Processes and Models.- Slope Instability of Continental Margins.- Margin Building - Regulating Processes.- Fluid Flow and Subsurface Material Transport.- Fluid Flow in Continental Margin Sediments.- Macrobenthic Activity and its Effects on Biogeochemical Reactions and Fluxes.- Cold Seep Communities on Continental Margins: Structure and Quantitative Distribution Relative to Geological and Fluid Venting Patterns.- The Importance of Mineralization Processes in Surface Sediments of Continental Margins.- Numerical Modelling of Transport Processes in the Subsurface.- Subsurface Fluid Flow and Material Transport.- Benthic Population Dynamics and Relationship to Sedimentary Settings.- Benthic Biodiversity Across and Along the Continental Margin: Patterns, Ecological and Historical Determinants, and Anthropogenic Threats.- Molecular Ecology and Evolution of Slope Species.- Larval and Reproductive Strategies on European Continental Margins.- Factors Controlling Soft Bottom Macrofauna Along and Across European Continental Margins.- Reef-Forming Cold-Water Corals.- Life at the Edge: Achieving Prediction from Environmental Variability and Biological Variety.- Microbial Systems in Sedimentary Environments.- Processes driven by the Small Sized Organisms at the Water-Sediment Interface.- Nucleic Acid-Based Techniques for Analyzing the Diversity, Structure, and Function of Microbial Communities in Marine Waters and Sediments.- Carbonate Mounds as a Possible Example for Microbial Activity in Geological Processes.- S. Guidard and the ODP "Proposal 573" Team.- The Anaerobic Oxidation of Methane: New Insights in Microbial Ecology and Biogeochemistry.- Microbial Systems in Sedimentary Environments of Continental Margins.

M. Schlueter

Papers

Ocean Margin Systems