ALBERT

Description: Tropical South America is one of the three main centres of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the 'Walker' circulation1). Although this area plays a key role in global climate cycles, little is known about South American climate history. Here we describe sediment cores and down-hole logging results of deep drilling in the Salar de Uyuni, on the Bolivian Altiplano, located in the tropical Andes. We demonstrate that during the past 50,000 years the Altiplano underwent important changes in effective moisture at both orbital (20,000-year) and millennial timescales. Long-duration wet periods, such as the Last Glacial Maximum—marked in the drill core by continuous deposition of lacustrine sediments—appear to have occurred in phase with summer insolation maxima produced by the Earth's precessional cycle. Short-duration, millennial events correlate well with North Atlantic cold events, including Heinrich events 1 and 2, as well as the Younger Dryas episode. At both millennial and orbital timescales, cold sea surface temperatures in the high-latitude North Atlantic were coeval with wet conditions in tropical South America, suggesting a common forcing.

Description: Long sediment cores recovered from the deep portions of Lake Titicaca are used to reconstruct the precipitation history of tropical South America for the past 25,000 years. Lake Titicaca was a deep, fresh, and continuously overflowing lake during the last glacial stage, from before 25,000 to 15,000 calibrated years before the present (cal yr B.P.), signifying that during the last glacial maximum (LGM), the Altiplano of Bolivia and Peru and much of the Amazon basin were wetter than today. The LGM in this part of the Andes is dated at 21,000 cal yr B.P., approximately coincident with the global LGM. Maximum aridity and lowest lake level occurred in the early and middle Holocene (8000 to 5500 cal yr B.P.) during a time of low summer insolation. Today, rising levels of Lake Titicaca and wet conditions in Amazonia are correlated with anomalously cold sea-surface temperatures in the northern equatorial Atlantic. Likewise, during the deglacial and Holocene periods, there were several millennial-scale wet phases on the Altiplano and in Amazonia that coincided with anomalously cold periods in the equatorial and high-latitude North Atlantic, such as the Younger Dryas.

Description: Modern competition research started with G.E. Hutchinson’s, Homage to Santa Rosalia, and his now-famous question “why are there so many species?” (Hutchinson 1959,1961). This confronted observed species richness with the competitive exclusion principle, a principle that had been derived from theory and from highly artificial experiments. It would always have been easy to point at the “artificial” character of the competitive exclusion principle. Indeed many researchers have refused to deal with Hutchinson’s question because they considered it a pseudo-problem, which arose from a contradiction between overly simplified theory and complicated reality. However, those who took Hutchinson’s challenge seriously have gained fundamental insights into how competition plays out in nature, how species coexist, and how communities function. In this final chapter we attempt to synthesize these insights as they have been presented in this book. We focus on six key topics: - Identification of major trade-off axes (Sect. 8.1) - Confirmation of the “intermediate disturbance hypothesis”, and detection of interactions among competition, resource supply, predation and disturbance in field experiments (Sect. 8.2) - The interplay of space colonization, dispersal and neighborhood competition in sessile communities (Sect. 8.3) - Potential for chaotic, self-generated heterogeneity in communities (Sect. 8.4) - Role of exclusive resources in competition among mobile animals (Sect. 8.5) - Coexistence by slow exclusion (Sect. 8.6)

Description: Markedly different cooling histories for the hanging- and footwall of theVari detachment on Syros and Tinos islands, Greece, are revealed by zircon and apatite fission-track data. The Vari/Akrotiri unit in the hangingwall cooled slowly at rates of 5–15 ◦CMyr−1 since Late Cretaceous times. Samples from the Cycladic blueschist unit in the footwall of the detachment on Tinos Island have a mean zircon fission-track age of 10.0±1.0 Ma, which together with a published mean apatite fission-track age of 9.4±0.5 Ma indicates rapid cooling at rates of at least ∼60 ◦CMyr−1. We derive a minimum slip rate of ∼6.5 kmMyr−1 and a displacement of 〉∼20 km and propose that the development of the detachment in the thermally softened magmatic arc aided fast displacement. Intra-arc extension accomplished the final ∼6–9 km of exhumation of the Cycladic blueschists from ∼60 km depth. The fast-slipping intra-arc detachments did not cause much exhumation, but were important for regionalscale extension and the formation of the Aegean Sea.

Description: The ocean accounts for over 90% of the active pools of carbon on the Earth’s surface, with over 95% of marine carbon in the form of dissolved inorganic carbon (DIC) (Hedges and Keil 1995). Organic carbon dissolved in the ocean, suspended as particles or cells, and accumulating in sediments together constitute the other significant fractions of marine carbon, with organic carbon in the water column similar in quantity to the current atmospheric inventory of carbon dioxide. Isotopic partitioning among various inorganic and organic carbon phases reflects biological, physical and chemical processes, and the resulting fractionations are important tools in the study of modern and ancient carbon cycling. The focus of this review is on the isotopic geochemistry of marine organic carbon. It will begin by setting the stage with the isotopic patterns of DIC in the modern oceans. As will be discussed below, the distribution of inorganic carbon and related nutrient concentrations as well as DIC isotopic compositions are important influences on the quantity and isotopic character of organic carbon produced in marine surface waters. The remainder of the review will discuss isotope fractionation associated with the production and preservation of marine organic carbon. The combination of organic matter composition and 13C content is a potentially powerful approach for addressing the nature and pace of ecological and environmental change both in the modern and ancient ocean. This work reviews biogeochemical processes that generate, transform and ultimately preserve such signatures in marine sediments.

Description: We use data from recently installed broad-band seismographs on the islands of Crete, Gavdos, Santorini, Naxos and Samos in the Hellenic subduction zone to construct receiver function images of the crust and upper mantle from south of Crete into the Aegean Sea. The stations are equipped with STS-2 seismometers and they are operated by GFZ Potsdam, University of Chania and ETH Zürich. Teleseismic earthquakes recorded by these stations at epicentral distances between 35° and 95° have been used to calculate receiver functions. The receiver function method is a routinely used tool to detect crustal and upper-mantle discontinuities beneath a seismic station by isolating the P–S converted waves from the coda of the P wave. Converted P–S energy from the oceanic Moho of the subducted African Plate is clearly observed beneath Gavdos and Crete at a depth ranging from 44 to 69 km. This boundary continues to the north to nearly 100 km depth beneath Santorini island. Because of a lack of data the correlation of this phase is uncertain north of Santorini beneath the Aegean Sea. Moho depths were calculated from primary converted waves and multiply reflected waves between the Moho and the Earth's surface. Beneath southern and eastern Crete the Moho lies between 31 and 34 km depth. Beneath western and northern Crete the Moho is located at 32 and 39 km depth, respectively, and behaves as a reversed crust–mantle velocity contrast, possibly caused by hydration and serpentinization of the forearc mantle peridotite. The Moho beneath Gavdos island located south of Crete in the Libyan Sea is at 26 km depth, indicating that the crust south of the Crete microcontinent is also thinning towards the Mediterranean ridge. This makes it unlikely that part of the crust in Crete consists of accreted sediments transported there during the present-day subduction process which began approximately 15 Ma because the backstop, i.e. the boundary between the current accretionary wedge of the Mediterranean ridge and the Crete microcontinent, is located approximately 100 km south of Gavdos. A seismic boundary at 32 km depth beneath Santorini island probably marks the crustal base of the Crete microcontinent. A shallower seismic interface beneath Santorini at 20–25 km depth may mark the depth of the detachment between the Crete microcontinent and the overlying Aegean subplate. The Moho in the central and northern Aegean, at Naxos and Samos, is observed at 25 and 28 km depth, respectively. Assuming a stretching factor of 1.2–1.3, crustal thickness in the Aegean was 30–35 km at the inception of the extensional regime in the Middle Miocene.

Description: (auf Grund eigener Messungen an Bord des Feuerschiffes "Fehmarnbelt" vom 9. August bis 5. September 1947 und vom 20. Februar bis 18. März 1948)

Description: Santorini, Greece is a major explosive volcano. The Santorini volcanic complex is composed of two active volcanoes—Nea Kameni and Mt. Columbo. Holocene eruptions have generated a variety of processes and deposits and eruption mechanisms pose significant hazards of various types. It has been recognized that, for major European volcanoes, few studies have focused on the social aspects of volcanic activity and little work has been conducted on public perceptions of hazard, risk and vulnerability. Such assessments are an important element of establishing public education programmes and developing volcano disaster management plans. We investigate perceptions of volcanic hazards on Santorini. We find that most residents know that Nea Kameni is active, but only 60% know that Mt. Columbo is active. Forty percent of residents fear that negative impacts on tourism will have the greatest effect on their community. In the event of an eruption, 43% of residents would try to evacuate the island by plane/ferry. Residents aged N50 have retained a memory of the effects of the last eruption at the island, whereas younger residents have no such knowledge. We find that dignitaries and municipal officers (those responsible for planning and managing disaster response) are informed about the history, hazards and effects of the volcanoes. However, there is no bemergency planQ for the island and there is confusion between various departments (Civil Defense, Fire, Police, etc.) about the emergency decision-making process. The resident population of Santorini is at high risk from the hazards associated with a future eruption.

Description: The morphology and structure of the submarine flanks of the Canary Islands were mapped using the GLORIA long-range side-scan sonar system, bathymetric multibeam systems, and sediment echosounders. Twelve young (〈2 Ma) giant landslides have been identified on the submarine flanks of the Canary Islands up to now. Older landslide events are long buried under a thick sediment cover due to high sedimentation rates around the Canary Islands. Most slides were found on the flanks of the youngest and most active islands of La Palma, El Hierro, and Tenerife, but young giant landslides were also identified on the flanks of the older (15–20 Ma) but still active eastern islands. Large-scale mass wasting is an important process during all periods of major magmatic activity. The long-lived volcanic constructive history of the islands of the Canary Archipelago is balanced by a correspondingly long history of destruction, resulting in a higher landslide frequency for the Canary Islands compared to the Hawaiian Islands, where giant landslides only occur late in the period of active shield growth. The lower stability of the flanks of the Canaries is probably due to the much steeper slopes of the islands, a result of the abundance of highly evolved intrusive and extrusive rocks. Another reason for the enhanced slope instability is the abundance of pyroclastic deposits on Canary Islands resulting from frequent explosive eruptions due to the elevated volatile contents in the highly alkalic magmas. Dike-induced rifting is most likely the main trigger mechanism for destabilization of the flanks. Flank collapses are a major geological hazard for the Canary Islands due to the sector collapses themselves as well as triggering of tsunamis. In at least one case, a giant lateral blast occurred when an active magmatic or hydrothermal system became unroofed during flank collapse.

Description: The morphological features associated with Co-rich manganese deposits, the size variations of nodules, and the occurrence of different substrates have been analyzed, to evaluate the influence of various seabed slope angles on the distribution of these features. The coverage and size of the crusts depend on their surface morphology and seabed topography, resulting in cobble-type, lineated, or step-like outcrops. Small nodules (1–4 cm in diameter) dominate all seabed slopes, with a few locations having nodules ranging from 1 to 8 or 1 to 10 cm. Sediments invariably occur as substrates for nodules and as cover for crusts, their coverage being inversely proportional to that of the nodules and crust outcrops.

Description: We investigated genetic differentiation among populations of the clonal grass Elymus athericus, a common salt-marsh species occurring along the Wadden Sea coast of Europe. While E. athericus traditionally occurs in the high salt marsh, it recently also invaded lower parts of the marsh. In one of the first analyses of the genetic population structure in salt-marsh species, we were interested in population differentiation through isolation-by-distance, and among strongly divergent habitats (low and high marsh) in this wind- and water-dispersed species. High and low marsh habitats were sampled at six sites throughout the Wadden Sea. Based on reciprocal transplantation experiments conducted earlier revealing lower survival of foreign genotypes we predicted reduced gene flow among habitats. Accordingly, an analysis with polymorphic cross-species microsatellite primers revealed significant genetic differentiation between high and low marsh habitats already on a very small scale (〈 100 m), while isolation-by-distance was present only on larger scales (60–443 km). In an analysis of molecular variance we found that 14% of the genetic variance could be explained by the differentiation between habitats, as compared to only 8.9% to geographical (isolation-by-distance) effects among six sites 2.5–443 km distant from each other. This suggests that markedly different selection regimes between these habitats, in particular intraspecific competition and herbivory, result in habitat adaptation and restricted gene flow over distances as small as 80 m. Hence, the genetic population structure of plant species can only be understood when considering geographical and selection-mediated restrictions to gene flow simultaneously.

Description: High concentrations of free C32 bis-homohopanoic acids (up to 433 μg/g dry wt) occur in microbial mats at methane seeps in anoxic Black Sea waters. These compounds show a strong preference for the ‘geological’ 17α(H),21β(H)- over the ‘biological’ 17β(H),21β(H)-configuration (αβ/ββ ratios up to 30.7) and indicate the potential formation of αβ-hopanoids in modern environments. Strong 13C-depletions (δ13C as low as −78.4‰ PDB) indicate an in situ generation of these hopanoids by biota involved in the anaerobic cycling of methane carbon. The inferred presence of hopanoids indigenous to a permanently anoxic marine environment is significant because these lipids are not known to occur in strictly anaerobic bacteria.

Description: Late glacial to post glacial sea-level changes provide direct evidence of the progress of melting of large ice sheets during the last deglaciation but, although the correlation between ice and ocean volumes is incontrovertible, the causal link is commonly obscured. Local effects including tectonics, isostatic and hydroisostatic responses and equatorial ocean-syphoning impose additional signals that hide the true picture. A detailed regional study of the Western Indian Ocean based on the analysis of drill cores carried out through modern reefs, in combination with observations and sampling of reef foreslopes, and investigations of outcrops provides a comprehensive data base. Sites from a range of tectonic settings include the microcontinental margins of Madagascar, the granitic Seychelles, and the isolated volcanic islands of Réunion, Mauritius and the Comoros in which the effects of subsidence can be shown to be small. These cover a range of latitudes, and comparisons with adjacent sites on continental margins allow the construction of sea-level curves that closely reflect the eustatic response and disengage this from the effects of other mechanisms. The Mayotte foreslope in the Comoro Islands provides the first coral reef record of sea-level change during the early deglaciation in the Indian Ocean (110–115 m below present sea level between 18,000 and 17,000 yr BP). Two distinctive reef terraces, at 90 and 60 m water depth are dated at 13,600 yr BP and partly attributed to the Younger Dryas period (12,700–11,600 cal yr BP). Reef drowning at around 13,500 yr BP may correspond to Meltwater Pulse 1A, and although there were surges in the rate of sea-level rise, most notably between 11,950 and 11,350 yr BP, there is little evidence to support a well-defined Meltwater Pulse 1B. Reconstructed Holocene sea-level curves are in good agreement and reflect a rapid sea-level rise of about 6 mm yr−1 between 10,000 and 7500 yr BP, followed by a clear inflection around 7500 yr BP when the rate fell to 1.1 mm yr−1. Modern reefs started to grow 8000–9000 years ago. In the post-glacial period the rate of sea-level rise was 1–1.5 mm yr−1 before stabilization at its present level 3000–2500 years ago. Curves for the 10,000–6000 yr−1 BP interval correspond closely with those predicted by theoretical models but lie below these in the subsequent period. In particular, and with the exception of the margins of the Madagascar microcontinent influenced by hydroisostatic processes, they do not reflect predicted higher sea-level stands during the late Holocene.

Description: The 14C-dating of microbial carbonate structures growing at methane seeps in anoxic waters of the Black Sea has shown a gradual increase with depth of the age of carbonates of these buildups. Comparing the radiocarbon age of the base and middle parts of the microbial structures gives an approximate time of origin of the deepest and shallowest microbial buildups as about 5300 and 2900 years before present, respectively. These dates correspond to the first appearance of hydrogen sulfide in the deepest Black Sea waters and to the stabilization of the upper boundary of the anoxic zone around the present-day level.

Description: According to small subunit ribosomal RNA (ss rRNA) sequence comparisons all known Archaea belong to the phyla Crenarchaeota, Euryarchaeota, and—indicated only by environmental DNA sequences—to the 'Korarchaeota'1, 2. Here we report the cultivation of a new nanosized hyperthermophilic archaeon from a submarine hot vent. This archaeon cannot be attached to one of these groups and therefore must represent an unknown phylum which we name 'Nanoarchaeota' and species, which we name 'Nanoarchaeum equitans'. Cells of 'N. equitans' are spherical, and only about 400 nm in diameter. They grow attached to the surface of a specific archaeal host, a new member of the genus Ignicoccus3. The distribution of the 'Nanoarchaeota' is so far unknown. Owing to their unusual ss rRNA sequence, members remained undetectable by commonly used ecological studies based on the polymerase chain reaction4. 'N. equitans' harbours the smallest archaeal genome; it is only 0.5 megabases in size. This organism will provide insight into the evolution of thermophily, of tiny genomes and of interspecies communication.

Description: Understanding how complex, highly variable sedimentary systems interact in time and space to release, transport and concentrate diamonds is the basis for successful exploration strategies for placer diamond deposits. De Beers’ and Namdeb's West Coast operations are widely involved in a variety of applied scientific research to unravel the complex interactions of Cainozoic fluvial, marine and aeolian systems that have contributed to the formation of the most spectacular gem diamond placer in the world. Geological models produced not only provide the basis for exploration target selection but also high-resolution orebody characterisation, a prerequisite for high confidence geostatistical evaluation, mining system design and mine planning. This paper draws on some of the many applied research projects that have contributed to De Beers’ and Namdeb's placer exploration success that continues to deliver new mineral resources on the West Coast. The history of the Orange River has, and continues to be intensively studied both on- and offshore as the principal conduit for diamond introduction to the continental margin. Use of the “Jago” submersible has introduced a new dimension to offshore sedimentological studies on the continental shelf through direct seafloor observation, which helped us to identify the latest deep-water offshore development—the late Pliocene/early Pleistocene Orange River fan-delta.

Description: Massive microbial mats covering up to 4-meter-high carbonate buildups prosper at methane seeps in anoxic waters of the northwestern Black Sea shelf. Strong 13C depletions indicate an incorporation of methane carbon into carbonates, bulk biomass, and specific lipids. The mats mainly consist of densely aggregated archaea (phylogenetic ANME-1 cluster) and sulfate-reducing bacteria (Desulfosarcina/Desulfococcusgroup). If incubated in vitro, these mats perform anaerobic oxidation of methane coupled to sulfate reduction. Obviously, anaerobic microbial consortia can generate both carbonate precipitation and substantial biomass accumulation, which has implications for our understanding of carbon cycling during earlier periods of Earth's history.

Description: One concept of evolutionary ecology holds that a living fossil is the result of past evolutionary events, and is adapted to recent selective forces only if they are similar to the selective forces in the past. We describe the present environment of the living coelacanth Latimeria chalumnae Smith, 1939 at Grande Comore, western Indian Ocean and report depth-dependent cave distribution, temperature, salinity and oxygen values which are compared to the fish's distribution and its physiological demands. We studied the activity pattern, feeding behaviour, prey abundance and hunting success to evaluate possible links between environmental conditions, feeding ecology and evolutionary success of this ancient fish. Transmitter tracking experiments indicate nocturnal activity of the piscivorous predator which hunts between approximately 200 m below the surface to 500 m depth. Fish and prey density were measured between 200 and 400 m, both increase with depth. Feeding tracks and feeding strikes of the coelacanth at various depths were simulated with the help of video and laser techniques. Along a 9447 m video transect a total of 31 potential feeding strikes occurred. Assuming 100% hunting success, medium-sized individuals would obtain 122 g and large females 299 g of prey. Estimates of metabolic rates revealed for females 3.7 ml O2 kg−1 h−1 and for males 4.5 ml O2 kg−1 h−1. Today coelacanths are considered to be a specialist deep-water form and to inhabit, with their ancient morphology, a contemporary environment where they compete with advanced, modern fish.

Description: The living coelacanth Latimeria chalumnae has a unique position in world biodiversity which raises important questions about conservation and ethics. Some relevant details of coelacanth biology are summarized, including those obtained by direct observation from submersibles. The importance of the coelacanth for evolutionary theory and palaeontology is shown to be paralleled in cultural, literary and artistic areas of human heritage. Threats to the Comoran coelacanths from artisanal fishing are described and conservation measures discussed in relation to local customs and economies as well as the promotion of tourism to spread a new awareness and concern for coelacanths worldwide.

Description: A fine-resolution MOM code is used to study the South China Sea basin-scale circulation and its relation to the mass transport through the Luzon Strait. The model domain includes the South China Sea, part of the East China Sea, and part of the Philippine Sea so that the currents in the vicinity of the Luzon Strait are free to evolve. In addition, all channels between the South China Sea and the Indonesian seas are closed so that the focus is on the Luzon Strait transport. The model is driven by specified Philippine Sea currents and by surface heat and salt flux conditions. For simplicity, no windstress is applied at the surface. The simulated Luzon Strait transport and the South China Sea circulation feature a sandwich vertical structure from the surface to the bottom. The Philippine Sea water is simulated to enter the South China Sea at the surface and in the deep ocean and is carried to the southern basin by western boundary currents. At the intermediate depth, the net Luzon Strait transport is out of the South China Sea and is fed by a western boundary current flowing to the north at the base of the thermocline. Corresponding to the western boundary currents, the basin circulation of the South China Sea is cyclonic gyres at the surface and in the abyss but an anti-cyclonic gyre at the intermediate depth. The vorticity balance of the gyre circulation is between the vortex stretching and the meridional change of the planetary vorticity. Based on these facts, it is hypothesized that the Luwn Strait transports are detennined by the diapycnal mixing inside the entire South China Sea. The South China Sea plays the role of a "mixing mill" that mixes the surface and deep waters to return them to the Luzon Strait at the intermediate depth. The gyre structures are consistent with the Stommel and Arons theory (1960), which suggests that the mixing- induced circulation inside the South China Sea should be cyclonic gyres at the surface and at the bottom but an anti-cyclonic gyre at the intermediate depth. The simulated gyre circulation at the intermediate depth has been confirmed by the dynamic height calculation based on the Levitus hydrography data. The sandwich transports in the Luzon Strait are consistent with recent hydrographical observations. Model results suggest that the Kuroshio tends to form a loop current in the northeastern South China Sea. The simulated Kuroshio Loop Current is generated by the pressure head at the Pacific side of the Luwn Strait and is enhanced by the ß-plane effects. The ß-plane appears to be of paramount importance to the South China Sea circulation and to the Luwn Strait transports. Without the ß-plane, the Luzon Strait transports would be greatly reduced and the South China Sea circulation would be complete- ly different.

Description: The deep ocean floor between the Clarion and Clipperton fracture zones (NE equatorial Pacific) has the highest known manganese nodule abundance in the world oceans. A detailed analysis of MR1 (Mapping Researcher 1, 11–12 kHz) sonar images and free-fall grab data in the Korean manganese nodule field areas reveals a close relationship between side-scan sonar characteristics of the seafloor and manganese nodule abundance. Eight sonar facies are identified based on back-scattering intensity and distribution patterns. These sonar facies can be interpreted as (1) volcanic seamounts (facies I-1), (2) bounding faults of abyssal hills (facies I-2 and II-1), (3) lava flows or volcanoclastic mass-flow deposits around the volcanic seamounts (facies I-3 and II-2), (4) crests of abyssal hills (facies II-1), (5) abyssal troughs between abyssal hills (facies III-1), (6) relatively flat areas (facies II-3 and III-2). In the areas where facies II-1 (abyssal hill crests with thin sediment cover) and II-3 (relatively flat areas draped by thin sediments) are dominant, manganese nodules occur abundantly. In contrast, zones comprising facies III-1 (abyssal troughs with thick sediment cover) and III-2 (relatively flat areas covered by thick sediments) are characterized by low abundance of manganese nodules. This relationship between distribution of sonar facies and manganese nodule abundance implies that (1) the qualitative difference in acoustic reflectivity of long-range sidescan sonar with some ground truth data is useful for regional assessment of manganese nodule occurrence over wide areas in a reasonable time, and (2) seafloor topography and sediment thickness are important controlling factors for regional occurrences of manganese nodules.

Description: A semi-quantitative assessment is made of the animals observed in archived videotapes taken from the research submersible Jago, during diamond mining and exploratory surveys off the mouth of the Orange River on the west coast of southern Africa (28°15′S, 29°11′S) in November 1996. The seabed environment is described and nekton associations with substratum features are identified. The area is characterized by heterogeneity to its physical and biological struture. The variety of observed nekton is low, and communities are dominated by goby Sufflogobius bibarbatus, juvenile hake Merluccius spp. and cuttlefish Sepia spp. (on soft substrata), as well as false jacopever Sebastes capensis and kingklip Genypterus capensis (on rocky substrata).

Description: A new species of terebellid polychaete, Lanice arakani sp. nov., is described from two specimens collected in deep water at seamounts of the west Pacific by the submersible `JAGO', and comparisons are made with the established species of the genus. Special reference is given to the morphology of the worm's sediment tube and in situ observations.

Description: Marine GeoSolutions (Pty) Ltd was contracted by the National Research Foundation (NRF) of South Africa to undertake a multibeam bathymetric survey of the northern KwaZulu-Natal submarine canyon system to define potential coelacanth habitats for the SA Coelacanth Conservation and Genome Resource Programme. Five survey blocks were defined to include all the known submarine canyons in the area. The survey blocks were systematically surveyed to develop a series of colour-draped bathymetric maps and three-dimensional models of the canyons. These maps were then used to provide information for potential submersible dive sites and produce the basal layer of a marine GIS (Geographical Information System).

Description: One kinds of glycolipid (SBI) have been isolated from the marine brown alga Sargassum hemiphyllum (Turn.) Ag. The structures of SBI have been determined as the sodium salt of 1-0-acyl-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol (acyl: tetradecanoyl, pentadecanoyl, 11-hexadecenoyl, hexadecanoyl, 10,13-octadecadienoyl, 9-octade cenoyl, 15-metylheptadecanoyl and 11-eicosenoyl 17:1.5:19:153:1:19:1:2) on the basis of chemical and spectral evidence and GC-MS analysis, respectively. Four constituents of the SBI were new compounds [the sodium salt of 1-0-(11″-hexadecenoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol, the sodium salt of 1-0-(10″,13″-octadecadienoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol, and the sodium salt of 1-0-(15″-metylhexadecenoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol, and the sodium salt of 1-0-(11″-eicosenoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol]. All compounds were isolated from marine brown alga for the first time.

Description: Sediment transport processes in the northern North Atlantic have been investigated on the basis of various numerical models. A general circulation model has been used to investigate large-scale particle transport, a reduced gravity plume model has been used to investigate particle transport by cascading from the shelves into the deep basins, an ocean slice model has been used to investigate particle exchange processes between a bottom current and the ambient water mass, and a Bottom Boundary Layer model has been used to investigate particle interactions influencing the settling behavior of suspended particles. In this paper, the various processes investigated in these models are described (i) schematically, (ii) on the basis of field data, if available, and (iii) by employing results from numerical simulations. In a first attempt the northern North Atlantic will be divided into separate process defined areas, which can be used in carbon budgeting, for example.

Description: Denitrification was investigated in the Baltic proper at two stations with different conditions in the deep water. The Gotland Deep was examined as an example of a basin with anoxic, H2S‐containing deep water and station T was taken as an example of low‐oxygen (〈0.2 ml liter−1), sulfide‐free deep water. Denitrification was measured by the acetylene blockage method; in addition, N2O reduction was followed in samples without acetylene. To shed light on the factors limiting denitrification, we compared in situ rates to denitrification after adding nitrate or electron donors. Denitrification was restricted to the layer of the oxic‐anoxic interface in the Gotland Deep and to the water layer near the sediment of station T. For both stations it could be shown that denitrification was not limited by nitrate availability. A lack of available organic C seemed to limit denitrification rates and growth of denitrifiers. As a result of C limitation in the water column, denitrification was restricted to energy‐rich interfaces. In the low‐oxygen water away from energy‐rich interfaces, the less C‐demanding nitrification‐denitrification coupling (NH4+ → N2O → N2) seemed to be favored. Denitrification in the water of the central Baltic seems to be subjected to strong variability due to changing C supply during the course of the year. However, limitation by C availability can be assumed for most of the year and should be taken into account in calculating the N budget of the Baltic.

Description: Localisation of deformation in narrow shear bands is a fundamental phenomenon of granular material behaviour. When modelling granular materials, shear localisation has therefore to be considered. The model must include an adequate constitutive law with an intrinsic length determining the thickness of the localised shear zones, and a representation of microscopic inhomogeneities triggering shear localisation. In the framework of a Cosserat continuum the behaviour of non-cemented granular material can be described by a hypoplastic law including the evolution of non-symmetric stresses and couple stresses. Void ratio fluctuations are introduced by a physically justified probability density function. The assumption is that fluctuations are minimal in the densest state, and maximal in the critical state. It is shown that shear bands can evolve spontaneously in the interior of a granular body even under homogeneous stress or displacement boundary conditions. Experimental verifications are given. Numerical results are compared with laboratory tests performed with a Cornforth and a Hamblytype biaxial apparatus. Shear localisation in the experiment is visualised by means of an optical method called particle image velocimetry. Further numerical results are compared with experimental results taken from publications.

Description: A series of true triaxial tests have been performed on rectangular prismatic specimens of Santa Monica Beach sand at three different relative densities to study the occurrence of failure, mechanisms that create failure, and soil behavior in the vicinity of failure. One mechanism is smooth peak failure, in which the soil continues to behave as a continuum with uniform strains, and smooth peak failure is followed by strain softening. Another mechanism is shear banding, whose occurrence in the plastic hardening regime limits the strength of the soil. Presented here are analyses based on theoretical conditions for localization and subsequent shear banding and on the results of the true triaxial tests. Thus, the strength increases as b [=(sigma (2) - sigma (3))/(sigma (1) - sigma (3))] increases from 0 to about 0.18, remains almost constant until b reaches 0.85, and then decreases slightly at b = 1.0. Shear banding initiates in the hardening regime for b-values of 0.18-0.85. Thus, peak failure is caused by shear banding in this middle range of b-values, and a smooth, continuous 3D failure surface is therefore not generally obtained for soils. The experimental results agree with the theoretical conditions for the occurrence of shear banding and its consequent effect on the 3D failure stress states for soil.

Description: Previous multivariate statistical analyses identified at least seven associations of sporomorphs within a major vegetational group of late Triassic-earliest Jurassic times identified as corresponding to arctic or cool-temperate climatic conditions. Detailed examination of how these associations responded to the climatic changes near the Triassic-Jurassic boundary allows them to be classified in terms of their thermophily and drought tolerance. These deductions also give rise to a fairly detailed reconstruction of climatic changes at the time. Consideration of the presumed family affinities of the various sporomorphs gives some support to the climatic interpretations; and allows tentative reconstructions of some of the vegetation.

Description: Cheng and co-workers showed how to make numerical simulations of crushable soils by the discrete element method (DEM). Stress-path tests on triaxial elements comprising crushable agglomerates have now been simulated. The plastic behaviour of this numerically generated soil closely resembles that of real sand. Crushing in the aggregate begins at stresses less than one tenth of the characteristic strength of single grains. The yield surfaces of isotropic ‘lightly overconsolidated’ DEM simulations are also contours of breakage, and are elliptical on Cambridge-style (q, p′) plots and symmetrical about the p′ axis. The points of maximum deviator stress at yield lie along lines of stress ratio My = ±0·8, but the plastic strain increments at yield are non-associated, giving more contraction than normality would allow. Significantly, therefore, the stress ratio My was found not to coincide with critical states. All stress-path simulations yielding with q/p′ 〉 My were found to satisfy the requirements of stress–dilatancy theory. In particular, their yielding was best described using a unique Mohr–Coulomb angle of internal friction ϕ, correlated with dilatancy rate. Points of zero dilation were found within this regime, providing a critical-state friction angle ϕcrit = 42° for these very ‘rough’ agglomerates. They also coincided with the location of a critical-state line on an e–log p′ plot. The peak angle (ϕpeak) developed in a variety of tests showed a unique correlation, reducing by progressive grain crushing as log σ′1 increased. As macroscopic stress levels approached the characteristic crushing strength of grains, it was impossible even to mobilise ϕ = ϕcrit, owing to large strains and high degress of breakage.

Description: Two modes of decrease in load bearing capacity of granular materials are discussed in view of experimental results. Both relate to the fact that frictional materials exhibit nonassociated plastic flow and they undergo considerable volume changes, either contraction or dilation. One mode consists of the instability that may occur in certain regions of stress space and potentially result in liquefaction of the granular material. It is the fact that loading of contracting soil (resulting in large plastic strains) can occur under decreasing stresses that may lead to unstable behavior under undrained conditions. As long as the soil remains drained, it will remain stable in the region of potential instability. The other mode is initiated by localization of plastic strains and subsequent development of shear bands, which in granular materials is followed by a decrease in load bearing capacity. These two modes are mutually exclusive and they occur for different loading and material conditions as discussed here on the basis of experimental observations.

Description: The Emlichheim oilfield is located in North-West-Germany on the Dutch-German border being the Southern downdip part of the Schoonebeek anticline. The field was discovered in 1943 and came on production in 1944. Since production startup, Wintershall operates the field as owner of the concession (90% share of interest) in a joint venture with Mobil Erdgas-Erdoel GmbH (10%). For more than 50 years an average crude oil production of 150.000 t/year has been maintained. Starting with huff "n" puff and hot water flooding in the late 60's, the first steam flood project was implemented in 1981. Further steamflood projects started in 1989, 1992, 1993, 1994 and 1998 in different areas of the field. Until 1997, only vertical production wells were drilled in the field. Wellbore stability seemed to be a major problem for drilling horizontal wells in the unconsolidated sandstone reservoir at that time. In 1999 an innovative steamflood project was started with three newly drilled horizontal producers surrounding a vertical steam injector. First results are showing a significant improvement in the performance as compared to the earlier projects and offer new chances for further development of the field. Today, the field could no longer be operated without the steam projects as roughly 95% of the field production is coming from thermal EOR. This paper gives a brief overview of the field and its production history, the planning and realization of a current steamflood project using horizontal well technology as well as its performance compared to the earlier projects. It also describes the experience of drilling horizontal wells in the unconsolidated sandstone. A brief outlook to the future field development is given.

Description: In vertebrates, genes of the major histocompatibility complex (MHC), with their pronounced polymorphism, potentially represent outstanding examples for the selective advantages of genetic diversity (1). Theoretical models predicted that, within an individual, MHC alleles can be subjected to two opposing selective forces, resulting in an optimal number of genes at intermediate individual MHC diversity (2, 3). Diversifying selection increases heterozygosity and enables wider recognition of pathogens (4). This process is opposed by the need to delete T cells that react with self peptide–MHC combinations (5) from the repertoire, which has been proposed as a possible mechanism constraining expansion of MHC genes. Because too high MHC diversity might delimit T cell diversity, it might also impose limitations on the efficiency of pathogen recognition. However, empirical evidence demonstrating fitness benefits in terms of parasite resistance caused by this type of optimal MHC diversity has been lacking. Therefore, we tested whether three-spined sticklebacks (Gasterosteus aculeatus L.) carrying an intermediate level of individual MHC diversity also displayed the strongest level of resistance against parasite infection. Sticklebacks are particularly suited to test MHC optimality, because MHC class II genotypes can differ markedly in the number of MHC class IIB alleles (6). We caught fish from an outbred population and used these to breed six sibships of immunologically naïve fish (i.e., they had no previous contact to parasites). Immunogenetic diversity ranged from three to nine MHC class IIB alleles found in reverse-transcribed messenger RNA (mRNA) [see (6) for details on genotyping]. The MHC genotypes within these sibships segregated above and below the hypothesized optimal number of ∼5 MHC class IIB alleles, which had previously been estimated in an epidemiological field survey (7). In individual infection treatments, fish from all sibships were simultaneously exposed to three of the most abundant parasite species identified in the field (Fig. 1A) (8). After two rounds of infection, separated by an interval of 8 weeks, we found a significant minimal mean infection rate at an intermediate number of individual MHC class IIB variants [i.e., 5.82 expressed alleles (Fig. 1B)]. This result was also confirmed when sibships were considered separately [i.e., 4.96 alleles (Fig. 1C)] (9). The strong pattern only appeared when infection with all three parasites was accounted for simultaneously. This may not be surprising, because single alleles are expected to correlate with single diseases and multiple alleles can contribute to resistance against several infectious agents (2).

Description: In vertebrates, genes of the major histocompatibility complex (MHC), with their pronounced polymorphism, potentially represent outstanding examples for the selective advantages of genetic diversity (1). Theoretical models predicted that, within an individual, MHC alleles can be subjected to two opposing selective forces, resulting in an optimal number of genes at intermediate individual MHC diversity (2, 3). Diversifying selection increases heterozygosity and enables wider recognition of pathogens (4). This process is opposed by the need to delete T cells that react with self peptide–MHC combinations (5) from the repertoire, which has been proposed as a possible mechanism constraining expansion of MHC genes. Because too high MHC diversity might delimit T cell diversity, it might also impose limitations on the efficiency of pathogen recognition. However, empirical evidence demonstrating fitness benefits in terms of parasite resistance caused by this type of optimal MHC diversity has been lacking. Therefore, we tested whether three-spined sticklebacks (Gasterosteus aculeatus L.) carrying an intermediate level of individual MHC diversity also displayed the strongest level of resistance against parasite infection. Sticklebacks are particularly suited to test MHC optimality, because MHC class II genotypes can differ markedly in the number of MHC class IIB alleles (6). We caught fish from an outbred population and used these to breed six sibships of immunologically naïve fish (i.e., they had no previous contact to parasites). Immunogenetic diversity ranged from three to nine MHC class IIB alleles found in reverse-transcribed messenger RNA (mRNA) [see (6) for details on genotyping]. The MHC genotypes within these sibships segregated above and below the hypothesized optimal number of ∼5 MHC class IIB alleles, which had previously been estimated in an epidemiological field survey (7). In individual infection treatments, fish from all sibships were simultaneously exposed to three of the most abundant parasite species identified in the field (Fig. 1A) (8). After two rounds of infection, separated by an interval of 8 weeks, we found a significant minimal mean infection rate at an intermediate number of individual MHC class IIB variants [i.e., 5.82 expressed alleles (Fig. 1B)]. This result was also confirmed when sibships were considered separately [i.e., 4.96 alleles (Fig. 1C)] (9). The strong pattern only appeared when infection with all three parasites was accounted for simultaneously. This may not be surprising, because single alleles are expected to correlate with single diseases and multiple alleles can contribute to resistance against several infectious agents (2).

Description: Das Laptevmeer stand in den letzten Jahren im Mittelpunkt vieler interdisziplinärer Studien. Seine Hydrographie wird wesentlich charakterisiert durch den saisonalen Einstrom gewaltiger Wassennassen aus den sibirischen Flüssen, besonders der Lena, welcher nicht nur Süßwasser, sondern auch große Mengen Seston und Nährstoffe ins Laptevrneer einträgt (z.B. Timokhov 1994, Alabyan et al. 1995, Pivovarov et al. 1999). Ein weiteres Merkmal ist die lang andauernde Eisbedeckung, mit nur wenigen eisfreien Sommermonaten. So wird eine extrem variable Umwelt für die Planktonorganismen des Laptevmeeres bezogen auf Wassertemperatur und Salinität, Wassertrübung und Nährstoffe(Lischka et al. 200 l) geschaffen.

Description: Analysis of 12,000 electronic still camera images collected with the ARGO II vehicle near the Trans-Atlantic Geotraverse (TAG) active hydrothermal mound, 26°N on the Mid-Atlantic Ridge, has made possible the first quantitative in situ assessment of both fissure orientation and width within the median valley of a slow-spreading ridge. Fissures near the TAG mound are partially rubble-filled extensional fractures that cut lightly sedimented seafloor and in ∼1% of our observations host pillow lavas. Fissure widths range from 0.15 to 3.5 m, with a mean of 0.7 m, and do not vary systematically within the survey area. First-order estimates of crack depth, based on these width measurements and reasonable elastic moduli, indicate that fissures are restricted to depths 〈500 m, with a mean depth of ∼70 m. Fissure-associated eruptives were therefore probably fed by shallow propagating dikes. TAG fissures exhibit a wide range of orientations, with ∼40% deviating by 〉45° from the strike of the ridge axis. The formation of obliquely oriented fissures requires that the local least compressive stress direction varies (at least temporarily) from that predicted by the regional tectonic stress field associated with plate separation. This stress field reorientation may be facilitated by variations in the style of magma emplacement within the rift. The close spatial association of long-term hydrothermal activity, fissure-hosted lava flows, and faults and fissures trending oblique to the spreading axis suggests a causal relationship between the impact of dike intrusion and the maintenance of localized hydrothermal flow.

Description: Im Nordpolarmeer gehört die Aufsammlung benthischer Organismen zu den ältesten wissenschaftlichen Aktivitäten. Die in erster Linie taxonomischen und zoogeographischen Fragestellungen beschränkten sich allerdings auf die flachen, im Sommer Eis freien Sehelfbereiche.

Description: While all modern crinoids are benthic filter feeders, some fossil species found in low-oxygen Konservat-Lagerstätten probably were pelagic. Pseudoplanktonic forms were mostly attached to driftwood (Seirocrinus, Traumatocrinus, Melocrinus); they had long, rope-like stems and enlarged, permanently splayed filter fans, as required for a passive tow-net function. However, the short and heavily cirrated stem of another driftwood-dweller (Pentacrinites) suggests active filter feeding. If the buoyant lobolith of Scyphocrinites acted as a swim bladder, this crinoid, by the same tow-net principle, could have made use of velocity gradients near a boundary layer. Paradigms are different for stemless forms, whether they floated passively over the bottom (Uintacrinus) or filtrated actively in the water column (Roveacrinids and Saccocoma). Some of the proposed models could not function with the muscular and ligamentary system of modern forms. Nevertheless, they represent distinctive peaks in the adaptive landscape that can be tested using taphonomic, morphological, and evolutionary evidence.

Description: Siliceous and calcareous sponges commonly are treated with acid to remove the spicules prior to embedding and cutting for histological investigations. Histology of spiculated sponge tissue represents a challenging problem in sponge histotechnology. Furthermore, fluorescence in situ hybridization (FISH), a key method for studying sponge-associated microbes, is not possible after acid treatment. For a broad range of siliceous sponge species, we developed and evaluated methods for embedding in paraffin, methylmethacrylate resins, LR White resin and cryomatrix. Different methods for cutting tissue blocks as well as mounting and staining sections also were tested. Our aim was to enable histological investigations and FISH without prior removal of the spicules. To obtain an overview of tissue and skeleton arrangement, we recommend embedding tissue blocks with LR White resin combined with en bloc staining techniques for large specimens with thick and numerous spicules, but paraffin embedding and subsequent staining for whole small specimens. For FISH on siliceous sponges, we recommend Histocryl embedding if the spicule content is high, but paraffin embedding if it is low. Classical histological techniques are used for detailed tissue examinations.

Description: The chief host of cadmium in zinc deposits is sphalerite, the cadmium content of which depends on the type of deposit. Sphalerite from Mississippi Valley-type (MVT) deposits has high cadmium concentrations whereas sphalerite from exhalative deposits has low cadmium concentrations. The Cd content of sphalerite depends on the Cd/Zn ratio, ligand activities, and temperature of the ore-forming fluids. The combined effect of variation of temperature, pH, total activity of reduced sulfur, and activity of Cl- cannot by itself account for either Cd depletion (exhalative deposits) or Cd enrichment (MVT deposits). Variations in the Cd/Zn ratio of the fluid have a significant effect in determining that of sphalerite. Basinal brines, which can considered to be the recent equivalents of MVT fluids, have high Cd/Zn ratios, and active exhalative systems are characterized by low Cd/Zn ratios. Probably the differences in sphalerite composition between the different deposit types are less a function of temperature and ligand activities than Cd/Zn ratio of the ore-forming fluids. In the hydrothermal environment, the Cd/Zn ratio is generally not high enough to allow crystallization of cadmium sulfides (greenockite or hawleyite). The abundance of greenockite in the supergene alteration zone of hydrothermal zinc deposits can be explained on the basis of Zn scavenging by crystallizing smithsonite.

Description: Ulva ohnoi Hiraoka et Shimada sp. nov. (Ulvales, Ulvophyceae) is described from southern and western Japan and is characterized by the following combination of features: (i) the large, fragile, easily torn thalli, which are 30–55 μm thick in the upper and middle regions and often have microscopic marginal teeth; (ii) the production of zoids in the upper marginal region; (iii) a regular alternation of dioecious gametophytes and a sporophyte; (iv) the production of free-floating thalli from torn-off attached thalli, which reproduce vegetatively by fragmentation and form green tides in summer to autumn; (v) disorderly arranged cells that are polygonal or quadrangular in the upper and middle regions; and (vi) the chloroplast covering the outer face of cell, with 1–3 pyrenoids. Ulva ohnoi differs from U. armohcana Dion et al., U. fasciata Delile, U. reticulata Forsskal, U. scandinavica Eliding and U. spiulosaOkamura et Segawa, which all possess microscopic marginal serrations, in thallus shape, cell shape or life history pattern. It is also distinguished from morphologically similar species by sequences of the nuclear encoded internal transcribed spacers and the 5.8S ribosomal RNA gene and the plastid encoded large subunit of ribulose-l,5-bisphosphate carboxylase/oxgenase gene. Furthermore, crossing tests demonstrate that there is a reproductive boundary between U. ohnoi and the most closely related species, U. fasciata and U. reticulata.

Description: Zeolites have been known since the mid-1750s, but prior to the early 1950s, most reported occurrences of zeolites were in fracture fillings and amygdules in igneous rocks, particularly basaltic lava flows. Indeed, most of the large attractive zeolite specimens in museum collections were obtained from lavas. In recent years, zeolites have been recognized as important rock-forming constituents in low-grade metamorphic rocks and in a variety of sedimentary rocks. Most zeolites in sedimentary rocks are finely crystalline, that is they occur as microscopic or submicroscopic crystals, and they are therefore of little appeal to mineral collectors; however, deposits of this type are voluminous and have great geologic significance and economic potential.

Description: Aromatic/heterocyclic sulfonamides act as strong inhibitors of the zinc enzyme carbonic anhydrase (CA; EC 4.2.1.1), but the presently available compounds do not generally discriminate between the 14 isozymes isolated in higher vertebrates. Thus, clinically used drugs from this class of pharmacological agents show many undesired side effects due to unselective inhibition of all CA isozymes present in a tissue/organ. Here we propose a new approach for the selective in vivo inhibition of membrane-bound versus cytosolic CA isozymes with a new class of positively charged, membrane-impermeant sulfonamides. This approach is based on the attachment of trisubstituted-pyridinium-methylcarboxy moieties (obtained from 2,4,6-trisubstituted-pyrylium salts and glycine) to the molecules of classical aromatic/heterocyclic sulfonamides possessing free amino, imino, hydrazino, or hydroxyl groups in their molecules. Efficient in vitro inhibition (in the nanomolar range) was observed with some of the new derivatives against three investigated CA isozymes:  i.e., hCA I, hCA II (cytosolic forms), and bCA IV (membrane-bound isozyme) (h = human isozyme; b = bovine isozyme). Due to their salt-like character, the new type of inhibitors reported here, unlike the classical, clinically used compounds (such as acetazolamide, methazolamide, and ethoxzolamide), are unable to penetrate through biological membranes, as shown by ex vivo and in vivo perfusion experiments in rats. The level of bicarbonate excreted into the urine of the experimental animals perfused with solutions of the new and classical inhibitors undoubtedly proved that:  (i) when using the new type of positively charged sulfonamides, only the membrane-bound enzyme (CA IV) was inhibited, whereas the cytosolic isozymes (CA I and II) were not affected; (ii) in the experiments in which the classical compounds (acetazolamide, benzolamide, etc.) were used, unselective inhibition of all CA isozymes (I, II, and IV) has been evidenced.

Description: Abstract: Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260–287 K and confining pressures of 50–100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation — whether arranged structurally between and (or) cementing sediment grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

Description: Although generally considered a poor cousin of Au-rich deposits such as orogenic or epithermal deposits, a significant number of volcanic-hosted massive sulfide (VHMS) deposits are significant repositories of Au. Several of these deposits had original Au resources exceeding 8 Moz and in some recently discovered deposits Au, not base metals, is the primary economic metal. Although most Au in volcanic-hosted massive sulfide districts is hosted by massive sulfide lenses, recent discoveries, both on land and on the ocean floor, indicate that significant Au occurs outside of these lenses. In most deposits, Au has a metallogenic association with either Cu or Zn. When associated with Cu, Au is concentrated toward the base of the massive sulfide lens. Gold-rich deposits of this metallogenic assemblage commonly are associated with (metamorphosed) advanced argillic assemblages and are inferred to have formed from acidic, high-temperature (〉300°C), oxidized fluids. These deposits have been equated to high-sulfidation epithermal deposits and may be detected using recently developed spectral techniques such as PIMA (Portable Infrared Mineral Analyzer) and airborne hyperspectral scanners. When associated with Zn, Au is concentrated near the top of massive sulfide lenses, in some cases in baritic zones. Gold-rich deposits of this metallogenic assemblage tend to be formed from low-temperature (200° ± 50°C) and/ or near-neutral fluids as indicated by fluid inclusion studies or by alteration assemblages (e.g., Kfeldspar or carbonate). A small number of deposits cannot be classified into the Au-Zn or Au-Cu association. In these deposits, Au is concentrated in pyritic zones that contain relatively low amounts of base metals. Moreover, a consistent relationship with Zn or Cu is not present. Although this group is small, it includes deposits such as Horne. Mineralogically Au can occur in electrum or native gold, Au tellurides, or auriferous pyrite or arsenopyrite. In deposits of the Au-Cu association, Au tends to occur as native gold or tellurides, whereas electrum and auriferous pyrite and/ or arsenopyrite is more common in the Au-Zn association. Metamorphic recrystallization tends to liberate Au held in auriferous pyrite or arsenopyrite, potentially enhancing metallurgical recoveries.

Description: Fault tolerance is an important aspect in the development of control systems for multi-legged robots since a failure in a leg may lead to a severe loss of static stability of a gait. In this paper, an algorithm for tolerating a locked joint failure is described in gait planning for a quadruped robot with crab walking. A locked joint failure is one for which a joint cannot move and is locked in place. If a failed joint is locked, the workspace of the resulting leg is constrained, but legged robots have fault tolerance capability to continue walking maintaining static stability. A strategy for fault-tolerant gaits is described and, especially, a periodic gait is presented for crab walking of a quadruped. The leg sequence and the formula of the stride length are analytically driven based on gait study and robot kinematics. The adjustment procedure from a normal gait to the proposed fault-tolerant crab gait is shown to demonstrate the applicability of the proposed scheme.

Description: The torque generated by a rotating joint comprises the useful force exerted by the joint on the external environment, and both the magnitude and distribution of torque through the step cycle during walking are important variables in understanding the mechanics of walking. The mechanics of the American lobster (Homarus americanus) and snow crab (Chionoecetes opilio) during walking were modelled to examine the relative roles of flexor versus extensor apodeme–muscle complexes, investigate which legs of these decapods likely contribute the greatest to locomotion, determine scaling effects of torque generation, and assess the relative roles of various model variables on torque production. Force generated along the length of the apodeme by the muscle was modelled based on apodeme surface area, muscle stress, and muscle fibre pinnation angle. Torque was then calculated from this estimated force and the corresponding moment arm. The flexor apodeme–muscle complex is calculated to generate consistently greater forces than the extensor, and generally this results in flexor torque being larger than extensor, though the snow crab does illustrate the opposite in two of its legs. This greater torque generation in flexion suggests that, in addition to the pushing of the trailing legs, the pulling action of the leading legs may play a significant role, at least during lateral walking. Leg 4 of both species appears to generate greater torques and thus provide the greatest forces for locomotion. Torque generation as a function of body size shows a second order response due to the increase in apodeme surface area. The pinnation angle of the muscle fibre is found to be insignificant in force generation, apodeme surface area (representing muscle cross sectional area) likely plays the most influential role in total force production, and moment arm controls the distribution of this force through the step cycle. Muscle stress remain a largely unknown quantity however, and may significantly affect both magnitude and distribution through step cycle of forces, and thus torque. Despite the uncertainty associated with the muscle stress parameter, the modelled results fit well with previously published force measurements.

Description: New data obtained during re-mapping of the northern part of Syros (Cyclades, Greece) allow the refinement of existing concepts about the structural evolution of this island. A metabasite belt and its metasedimentary envelope near Kampos and San Michali were mapped at a 1:5000 scale, with special emphasis on the structural inventory. The HP/LT rocks (P , 1.5 GPa; T , 500 8C at ,50 Ma) exposed are intensely deformed by at least two isoclinal folding events. Relative age relations between deformation and peak metamorphism indicate that isoclinal folding took place before or during peak metamorphism. Later deformation stages include Miocene non-penetrative upright kink folding and crenulation, transpressional strike-slip faulting, and open upright cylindrical folding, followed by the development of steep normal faults. Taking into account recent zircon U–Pb geochronological constraints, lithostratigraphic observations, and published data on the Neogene structural evolution of the Aegean, we present a history for the rocks of Syros, beginning with the formation of the oceanic crust(represented by the metabasites) to the present.

Description: Elevated concentrations of certain large ion lithophile elements (LILE; e.g., Ba, K, Rb, Cs, Ca, Sr), U, and Pb in arc magmas relative to high field strength elements (HFSE; e.g., Ti, Th, Hf, Nb, Zr) are considered key indicators of fluid addition to arc magma source regions worldwide, but the fluid sources and processes of mass transfer are controversial. Dehydration of downgoing slabs releases fluids that can flow through and react with metamorphosed ultramafic-mafic rock packages in me´lange zones near slab-mantle interfaces. New geochemical data from Syros, Greece, reveal that these fluids preferentially leach LILEs, U, and Pb when they infiltrate and react with subducted metasedimentary rocks. Transfer of these LILE-, U-, and Pb-enriched fluids to the mantle wedge at subarc depths could directly trigger partial melting and generate magmas with elevated Ba/Th, Sr/Th, Pb/Th, and U/Th, as well as radiogenic Sr. Alternatively, if fluid transfer occurs at shallower depths (e.g., Syros), the metasomatized mantle could be carried deeper by wedge corner flow to ultimately undergo partial melting in subarc regions.

Description: Volcanology has been in the past and in many respects remains a subject dominated by pure research grounded in the earth sciences. Over the past 30 years a paradigm shift has occurred in hazard assessment which has been aided by significant changes in the social theory of natural hazards and the first-hand experience gained in the 1990s by volcanologists working on projects conceived during the International Decade for Natural Disaster Reduction (IDNDR). Today much greater stress is placed on human vulnerability, the potential for marginalisation of disadvantaged individuals and social groups, and the requirement to make applied volcanology sensitive to the characteristics of local demography, economy, culture and politics. During the IDNDR a methodology, broadly similar to environmental impact analysis, has emerged as the preferred method for studying human vulnerability and risk assessment in volcanically active regions. The characteristics of this new methodology are discussed and the progress which has been made in innovating it on the European Union laboratory volcanoes located in western Europe is reviewed. Furnas (São Miguel, Azores) and Vesuvius in Italy are used as detailed case studies.

Description: In order to explain biological zonation, shore height above the ordnance level is frequently used as an indicator of the abiotic gradient in intertidal ecosystems. This is based on the implicit assumption that shore height is directly correlated with inundation frequency and/or duration. Despite the importance of inundation for tidal ecosystems, measurements have rarely been taken directly by measuring inundation at the site of investigation. We measured mean high tide (MHT) and flooding frequency at three sites on the Dutch Barrier Island of Schiermonnikoog. To assess the scale dependence, we compared local measurements with the estimated inundation frequencies based on the official tide gauge (OTG) farther away. Locally measured MHT water levels differed among sites and were consistently higher than estimated MHT water levels. With this data, we subsequently estimated the inundation frequency of vegetation plots from our measurements and correlated it with species distribution. In a logistic regression inundation frequency accounted for twice the variance in explaining the dominance of three salt marsh species than shore height. The discrepancy in annual inundation frequency of the vegetation between sites was ≦300% for a given shore height. Within each site replicated estimates of inundation frequency proved to be consistent (scale 10–50 m). Estimated and measured inundation frequencies thus reliably correlated at a small-scale (tens of metres), but not at a larger scale (hundreds of metres to kilometres). If inundation frequency is used as an explanatory variable, it will therefore be advisable to consider the spatial heterogeneity of the measurements, in particular if different sites are to be compared. We give mean inundation frequencies of three dominant salt marsh species (Elymus athericus, Festuca rubra, Artemisia maritima) measured over 1 year.

Description: A submersible dive undertaken over seabed outcrop situated on the middle shelf off the Namaqualand coast, at a depth of 136 to 140 mbsl, about 32km offshore, revealed an abundance of in-situ fossil tree trunks in exposed Late Cretaceous (Late Coniacian) seafloor outcrop. Based on regional Side Scan Sonar interpretations, it would appear that this outcrop is unique to the dive location, covering an approximate 2km2 area of seabed. Integration of these observations with a regional seismic stratigraphic and biostratigraphic framework has enabled more accurate constraints to be placed on the ages of the wood than was previously possible. Two species of fossil wood belonging to the Podocarpaceae were identified from samples collected by the submersible: Podocarpoxylon jago Bamford and Stevenson and P. umzambense Schultze-Motel. Palaeoenvironmental analysis shows that the proximal Coniacian succession for the Orange Basin was typified by a well-vegetated coastal plain, which was periodically waterlogged. The coastal plain experienced repeated periods of progressive drowning of the incised valley systems cutting through the coastal plain and the subsequent development of wave-dominated estuarine incised valley fill systems. The fossil wood recovered from the dive-site is typified by a lack of distinct growth ring development. This implies either a lack of seasonality or sufficient available water all year round, with no low temperatures to stop plant growth. This observation, together with complementary sedimentological and micropalaeontological analysis suggests a temperate palaeo-climate for the area.

Description: The presence of Solidobalanus auricoma (Cirripedia; Balanoidea) in the Red Sea at a depth of 112 m is reported, and its morphology is described. S. auricoma is a relatively deep water barnacle known from the Persian Gulf through Malaysia, southeastern Australia, and northeastern New Zealand at depths of 27 to 320 m. This is its first record from the Red Sea. The present finding of S. auricoma in the Gulf of Elat (Aqaba) extends the boundaries of its geographic distribution farther west and north.

Description: During mini-submersible dives in De Beers offshore concessions on the middle shelf of Namaqualand, on the west coast of South Africa, a fossil forest was located and sampled. Over an area of 2 km2 there are numerous in situ and prostrate trunks on a gentle slope, 136-140 m below sea level and about 32 km offshore. Micro-palaeontological dating shows that the sediments are of Coniacian age. The silicified woods have been identified as members of the Podocarpaceae and one new species is described, Podocarpoxylon jago Bamford & Stevenson sp. nov. The second species identified is P. umzambense Schultze-Motel. These woods are compared with other west coast woods, both onshore and offshore, and the Upper Cretaceous coastal environment is postulated.

Description: Videotapes collected by the research submersible Jago in the Benguela ecosystem during spring 1997 were analyzed to determine demersal nekton assemblage composition, fish behavior, and microscale habitat association, and habitat selection. Demersal fish assemblage diversity was generally low, and their composition was a function of substratum type. Individual species showed an often marked association with either rocky or soft substrata (or both), and a strong or weak selection for the associated biota. Soles and dragonets actively selected areas of bioactive soft substrata, to which they are behaviorally and morphologically adapted. False jacopever were associated with crevices in areas of high-relief rocky substrata. Kingklip are piscivorous and were largely confined to holes at the base of rocks and favored areas without a conspicuous epifauna. Juvenile hake and gobies avoided extremely rocky areas and were largely indifferent to the presence of benthic invertebrates—behavior that is consistent with their planktonic diets. These results represent the first direct observations of demersal nekton in the region and are important because they allow better interpretations of the results of trawl studies.

Description: Indices of β-diversity are of two major types, (1) those that measure among-plot variability in species composition independently of the position of individual plots on spatial or environmental gradients, and (2) those that measure the extent of change in species composition along predefined gradients, i.e. species turnover. Failure to recognize this distinction can lead to the inappropriate use of some β-diversity indices to measure species turnover. Several commonly-used indices of β-diversity are based on Whittaker's βW (βW = γ/α, where γ is the number of species in an entire study area and α is the number of species per plot within the study area). It is demonstrated that these indices do not take into account the distribution of species on spatial or environmental gradients, and should therefore not be used to measure species turnover. The terms ‘β-diversity’ and ‘species turnover’ should not be used interchangeably. Species turnover can be measured using matrices of compositional similarity and physical or environmental distances among pairs of study plots. The use of indices of β-diversity and similarity-distance curves is demonstrated using simulated data sets.

Description: Five large marine ecosystems are compared in respect to the signatures created by plots of number and average size of species by trophic level. Preliminary results suggest that these signatures are similar for similar ecosystems (here: Baltic Sea and Black Sea as examples of brackish, temperate ecosystems, and Caribbean and South China Sea as examples of tropical ecosystems), and different for different ecosystems (here: temperate vs tropical systems). Also, the shape and the position of the signatures appear to be predictable, as shown for the North Sea, which has a similar shape but intermediate position between the species-poor Baltic and Black Sea, and the species-rich tropical systems. Individual signatures can be interpreted and reveal special characteristics, as shown by the lower part of the Caribbean signature, which has a different trend then the other signatures, indicating that the Caribbean has relatively more herbivorous fishes. Fish data were extracted from www.fishbase.org. Preliminary signatures for cephalopods, marine mammals, and marine birds indicate the different roles of these groups in ecosystems. In the North Sea, vertebrates (fish, birds, marine mammals) and cephalopods are restricted to trophic levels above 3, with the exception of very few fish and bird species). Invertebrates are restricted to trophic levels below 3, again with very few exceptions.

Description: The distribution of early life stages of cephalopods was studied during a cruise of the German research vessel RV Poseidon to the Sargasso Sea in March 1993, covering an area south-east of Bermuda from 24°N to 31°N and 61°W to 65°W. Hydrographic measurements were conducted by CTD and/ or XBT. The subtropical convergence zone was detected at a latitude of approximately 27°20’N and divided the Sargasso Sea into a northern and a southern area. Zooplankton sampling with a 6m² Isaac Kidd midwater trawl and Bongo nets yielded a total catch of 909 early life stages of cephalopods representing at least 14 families and 23 mainly oceanic species. Multivariate statistical analyses were performed in order to compare the species composition and abundance of cephalopods. Two different assemblages were clearly identified, north and south of the front. According to the position of the front an analysis of similarity (ANOSIM) was applied which confirmed the observed differences in species composition on a highly significant level. The Cranchiidae, mainly represented by the endemic species Leachia lemur, was the most abundant family especially in the northern part of the Sargasso Sea and was mainly responsible for the distinction between the cephalopod assemblages. In general, higher abundances of early life stages and a higher diversity was observed north of the subtropical convergence zone, which is assumed to form a faunal boundary