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: 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: 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: 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: 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: 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.