ALBERT

Description: The well-known caldera of Thira (Santorini), Greece, was not formed during a single eruption but is composed of two overlapping calderas superimposed upon a complex volcanic field that developed along a NE trending line of vents. Before the Minoan eruption of 1400 B.C., Thira consisted of three Java shields in the northern half of the island and a flooded depression surrounded by tuff deposits in the southern half. Andesitic lavas formed the overlapping shields of the north and were contemporaneous with and, in many places, interbedded with the southern tuff deposits. Although there appears to be little difference between the composition of magmas erupted, differences in eruption style indicate that most of the activity in the northern half of the volcanic field was subaerial, producing lava flows, whereas in the south, eruptions within a flooded depression produced a sequence of mostly phreatomagmatic tuffs. Many of these tuffs are plastered onto the walls of what appears to have been an older caldera, most probably associated with an eruption of rhyodacitic tephra 100,000 years ago. The Minoan eruption of about 1400 B.C. had four distinct phases, each reflecting a different vent geometry and eruption mechanism. The Minoan activity was preceded by minor eruptions of fine ash. (1) The eruption began with a Plinian phase, from subaerial vent(s) located on the easternmost of the lava shields. (2) Vent(s) grew toward the SW into the flooded depression. Subsequent activity deposited large-scale base surge deposits during vent widening by phreatomagmatic activity. (3) The third eruptive phase was also phreatomagmatic and produced 60% of the volume of the Minoan Tuff. This activity was nearly continuous and formed a large featureless tuff ring with poorly defined bedding. This deposit contains 5–40% lithic fragments that are typical of the westernmost lava shield and appears to have been erupted when caldera collapse began. (4) The last phase consisted of eruption of ignimbrites from vent(s) on the eastern shield, not yet involved in collapse. Collapse continued after eruption of the ignimbrites with foundering of the eastern half of the caldera. Total volume of the collapse was about 19 km3, overlapping the older caldera to form the caldera complex visible today. Intracaldera eruptions have formed the Kameni Islands along linear vents concomitant with vents that may have been sources for the Minoan Tuff.

Description: Broadband receiver functions developed from teleseismic P waveforms recorded on the midperiod passband of Regional Seismic Test Network station RSCP are inverted for vertical velocity structure beneath the Cumberland Plateau, Tennessee. The detailed broadband receiver functions are obtained by stacking source‐equalized horizontal components of teleseismic P waveforms. The resulting receiver functions are most sensitive to the shear velocity structure near the station. A time domain inversion routine utilizes the radial receiver function to determine this structure assuming a crustal model parameterized by many thin, flat‐lying, homogeneous layers. Lateral changes in structure are identified by examining azimuthal variations in the vertical structure. The results reveal significant rapid lateral changes in the midcrustal structure beneath the station that are interpreted in relation to the origin of the East Continent Gravity High located northeast of RSCP. The results from events arriving from the northeast show a high‐velocity midcrustal layer not present in results from the southeast azimuth. This velocity structure can be shown to support the idea that this feature is part of a Keweenawan rift system. Another interesting feature of the derived velocity models is the indication that the crust‐mantle boundary beneath the Cumberland Plateau is a thick, probably laminated transition zone between the depths of 40 and 55 km, a result consistent with interpretations of early refraction work in the area.

Description: We have compiled both laboratory and worldwide field data on electrical conductivity to help understand the physical implications of deep crustal electrical profiles. Regional heat flow was used to assign temperatures to each layer in regional electrical conductivity models; we avoided those data where purely conductive heat flow suggested temperatures more than about 1000°C, substantially higher than solidus temperatures and outside the range of validity of heat flow models. The resulting plots of log conductivity σ versus 1/T demonstrate that even low-conductivity layers (LCL) have conductivities several orders of magnitude higher than dry laboratory samples and that the data can be represented by straight line fits. In addition, technically active regions show systematically higher conductivities than do shield areas. Because volatiles are usually lost in laboratory measurements and their absence is a principal difference between laboratory and field conditions, these materials probably account for the relatively higher conductivities of rocks in situ in the crust; free water in amounts of 0.01–0.1% in fracture porosity could explain crustal conductivities. Other possibilities are graphite, hydrated minerals in rare instances, and sulfur in combination with other volatiles. As most of the temperatures are less than 700°C, partial melting seems likely only in regions of highest heat flow where the conductive temperature profiles are inappropriate. Another result is that at a given temperature, crustal high-conductivity layers (HCL) are more conductive by another order of magnitude and show more scatter than do LCL's. Because the differences between HCL's and LCL's are independent of temperature, we must invoke more than temperature increases as a cause for large conductivity increases; increased fluid concentration in situ seems a probable cause for enhanced conductivities in HCL's. From the point of view of these observations, it does not matter whether the fluids are in communication with the surface or trapped at lithostatic pressures.

Description: The existence of a southward‐flowing current beneath the northern part of the seasonally reversing Somali Current is documented in a 2½‐year‐long time series of currents obtained at moored stations near 5°N about 30 km off the Somali coast. Its mean annual transport in the layer 150–600 m amounts to about 5×106 m3/s. The undercurrent has a pronounced seasonal cycle in phase with the near surface flow, suggesting a close coupling to the monsoonal wind forcing. With the spin‐up of the deepreaching northern Somali gyre after the onset of the southwest monsoon, the undercurrent is temporarily destroyed in the northern Somali Basin during June/July but is re‐established in August. The undercurrent does not reach 3°N but turns offshore north of that latitude.

Description: The titanium to aluminum ratio in core V19–29 is correlated with aluminosilicate accumulation rates. This correlation may be due to Pleistocene eolian transport fluctuations which alter the mean grain size of sedimented eolian material. The relation between aluminum accumulation rate and Ti/Al, established from accumulation rates integrated over 11,000–50,000 year intervals, can be inverted to compute a high‐resolution record of aluminosilicate and calcium carbonate accumulation rates over the past 130,000 years. Carbonate accumulation rates are closely related to the oxygen isotope record in the core, with a phase lag and damping constant that is compatible with the response time (shown to be only 6000 years) of calcium carbonate in the ocean. Carbonate sedimentation at this site responds to several processes independently correlated with climatic change. The relative importance of these processes for carbonate sedimentation at this site can be constrained by the record in this core and other lines of evidence: 15% of the increased carbonate deposition at this site during glacial periods may be due to diminished NADW (North Atlantic deep water) formation; 10% is due to carbonate productivity decreases in the North Atlantic; 25% may be due to a diminished shallow‐sea carbonate sink; and the residual 50% must be due to a local productivity increase. These assignments are consistent with observations on carbonate paleoceanography in the North Atlantic. Aluminosilicate accumulation rate variations correlate with the record of eolian quartz deposition near northwest Africa and, in a general way, with the climatic record. But in detail the record differs substantially from the oxygen isotope record and may provide independent evidence on the nature of climate dynamics.

Description: Basalts from the Reykjanes Ridge contain noble gases delivered from the non-degassed lower mantle by the Iceland plume. These lower mantle gases are thought to be a mixture of planetary and solar components, as would be expected if the Earth accreted from fine silicate particles.

Description: The eastern boundary of the Caroline plate, in the western equatorial Pacific, is composed of three structural provinces distinguished primarily on the basis of morphology. Each province shows evidence for convergence between the Caroline and Pacific plates though the structural style varies considerably between each province. Most notably, the sense of underthrusting appears to change along the boundary at about 3°N. To the south, at the Mussau System, Caroline lithosphere underthrusts beneath the Mussau Ridge (which is part of the Pacific plate), while to the north the Caroline plate appears to overthrust the Pacific plate. Recently collected seismic reflection profiles across each province documents the structural changes along and across strike of the Caroline-Pacific plate boundary. With this information, we estimate that a minimum of approximately 4 km of crustal shortening has occurred at about 5°N due to convergence of the two plates. Further to the south (about 2°N), simple gravity models suggest that about 10 km of Caroline lithosphere lies beneath the present-day Pacific plate. Using a previously determined pole of rotation describing Caroline-Pacific relative motion (Weissel and Anderson, 1978), we grossly estimate the duration of the convergence between these two plates at about one million years. It is suggested that variation in the convergence rate along the plate boundary provides the primary control on the variation of structural deformation observed between provinces; however, favorable thermal conditions are factors that are considered. If the eastern boundary of the Caroline plate is a region of incipient though perhaps transient subduction, as we postulate, then the geophysical and geological evidence presented can constrain models on the initiation of subduction.

Description: Strain accumulation and release at a subduction zone are attributed to stick slip on the main thrust zone and steady aseismic slip on the remainder of the plate interface. This process can be described as a superposition of steady state subduction and a repetitive cycle of slip on the main thrust zone, consisting of steady normal slip at the plate convergence rate plus occasional thrust events that recover the accumulated normal slip. Because steady state subduction does not contribute to the deformation at the free surface, deformation observed there is completely equivalent to that produced by the slip cycle alone. The response to that slip is simply the response of a particular earth model to embedded dislocations. For a purely elastic earth model, the deformation cycle consists of a coseismic offset followed by a linear‐in‐time recovery to the initial value during the interval between earthquakes. For an elastic‐viscoelastic earth model (elastic lithosphere over a viscoelastic asthenosphere), the postearthquake recovery is not linear in time. Records of local uplift as a function of time indicate that the long‐term postseismic recovery is approximately linear, suggesting that elastic earth models are adequate to describe the deformation cycle. However, the deformation predicted for a simple elastic half‐space earth model does not reproduce the deformation observed along the subduction zones in Japan at all well if stick slip is restricted to the main thrust zone. As recognized earlier by Shimazaki, Seno, and Kato, the uplift profiles could be explained if stick slip were postulated to extend along the plate interface beyond the main thrust zone to a depth of perhaps 100 km, but independent evidence suggests that stick slip at such depths is unlikely.

Description: Strandings of the giant squid, Architeuthis monachus (Steen-strup), have always stirred attention because of the rarity and enormous size of these cephalopods. These animals have never been observed in their natural habitat and little is known about their physiology and ecology. Stranding of giant squids in Newfoundland waters has been correlated with the inflow of warm water, suggesting that increased temperature may be causing their death1. Squids have also been carried to the Norwegian coast with the warm North Atlantic current2 and on 23 August 1982 a live specimen was caught off Radöy near Bergen, Norway (Fig. 1). This catch gave an unprecedented opportunity to study the effects of temperature on the oxygen binding properties of blood from the giant squid. The present finding of an excess of a fourfold decrease in O2 affinity when temperature is increased from 6.4 to 15°C strongly suggests that giant squids may suffocate from arterial desaturation when increased ambient temperatures are experierced.

Description: Samples collected at hourly intervals on May 18–19, 1980, at three sites 200 km downwind from Mount St. Helens, have made possible a detailed reconstruction of the conditions that contribute to the compositional heterogeneity of mineral and glass components observed in distal tephra layers. The air fall tephra deposited at the sites during the first 7 hours of the May 18 eruption is mostly coarse grained, microlite-rich, nonjuvenile glass and feldspar. Grain-size maxima in this initial tephra can be related to the cataclysmic blast at 0832 and a subsequent pulse of the eruption at 1200. Juvenile, microlite-free glass increases in relative abundance at the sampling sites beginning at about 1900. Such a change between nonjuvenile and juvenile tephra can be related to a 5-km increase in column height associated with the last major pulse of the eruption which occurred at 1700 at the volcano. Electron microprobe study of both microlite-rich and microlite-free pumice in the time series samples reveals significant compositional differences. Interstitial glass in nonjuvenile pumice deposited during the first few hours at the sampling sites is enriched in SiO2 and K2O and depleted in TiO2, FeO*, and MgO relative to juvenile glass. By comparison, major element composition of the least evolved juvenile glass sampled during the last several hours of the eruption displays a slight trend toward less evolved composition. Least squares calculations suggest that the more evolved character of the nonjuvenile glass can be explained by greater fractional crystallization brought about by enhanced cooling in a cryptodome prior to eruption, whereas the temporal changes observed in juvenile glass composition during the last several hours of the eruption suggest the presence of a small, slightly zoned magma chamber at depth. Electron microprobe study of glass-coated ilmenites, magnetites, and plagioclases provides the following estimates of the physical conditions in this reservoir: 865°±50°C, PH2O = 2.2 kbar and -log ƒO2 = 11.7. Analyses of bulk pumice, glass and selected mineral phases from May 25, June 12, July 22, and October 16–18 pumices erupted from Mount St. Helens indicate that the bulk pumice (magma) compositions have become slightly more andesitic with time, while mineral and co-existing glass compositions have changed significantly in post-May 18 eruptions with both being more highly evolved than those associated with the May 18 eruption. An application of the magnetite-ilmenite geothermometer to June 12 and July 22 samples indicates temperatures of 919°±30°C and 930°±50°C, respectively. Least squares calculations suggest that such evolved post-May 18 glass and mineral phases can be derived by fractional crystallization of a magma composition like bulk May 18 pumice into approximately 50% crystals and 50% residual liquid. Such partitioning between crystals and residual liquid appears to have occurred on the scale of centimeters and is interpreted as a consequence of accelerated crystallization under reduced water pressure.

Description: Sedimentation rates (corrected for compaction) from along the passive continental margin of Africa between the Equatorial Fracture Zone and Somalia are used to compare the rates of subsidence of the continental crust since early Mesozoic time. Three distinctive subsidence histories can be identified which correspond with basinal areas that have different structural styles: rifted (west coast), sheared (Equatorial and Agulhas fracture zones) and sunk (zones of vertical tectonics in eastern Africa). A comparison of subsidence rates with other tensional margins (NE USA and the North Sea) and a consideration of the plate tectonic history of the African margins leads to the proposal of a geo and thermodynamic model that takes cognizance of the worldwide mid-Cretaceous rheological discontinuity between taphrogenic and epeirogenic basin formation recognized by Kent, and the more generally accepted, purely plate tectonic driven model of margin subsidence. The new suggestion involves a lower Mesozoic worldwide rise in the geothermal gradient in the lithosphere which produces metamorphism of the base of the continental crust and initiates taphrogenesis along lineaments throughout Gondwanaland. A lowering of the geothermal gradient in the lower Cretaceous produces a switch to epeirogenic subsidence, driven solely by sediment loading and thermal contraction, by Aptian/Albian times. The thermal event facilitated continental separation, and sea floor spreading commenced locally at various times along the active taphrogenic belts. Local thermal and tectonic aberrations associated with this phenomenon over print onto the worldwide pattern of marginal basin subsidence. A further rise in the geothermal gradient may have been responsible for renewed taphrogenesis in eastern Africa in Tertiary times.

Description: The basement morphology and sediment thickness of the Hess Rise, an oceanic plateau in the central North Pacific, have been mapped on the basis of seismic reflection profiles. The acoustic stratigraphy on and around the rise is correlated with the lithostratigraphy at Deep Sea Drilling Project sites 464, 310, 465, and 466. A total sediment isopach chart of the rise reveals small-scale departures from the expected sedimentary pattern (thick sediment in shallow areas; thin sediment in deep areas). Sediment-filled basement depressions result from mass transport; thin sediment (〈50 m) occurs on steep scarps, basement ridges, and areas affected by bottom currents. A pre-Senonian sediment isopach chart shows a thickening from less than 50 m to more than 250 m of sediment from the northeast to the southwest. This trend seems explainable only in terms of the time-transgressive nature of seafloor formed at a mid-ocean ridge. The axial trend of the rise (N30°W) parallels nearby Mesozoic magnetic lineations and seems to be isochronous as deduced from the Deep Sea Drilling Project data. The Hess Rise began developing in late Aptian time along a segment of the Pacific-Farallon Ridge. Important events in the history of the rise are late-stage volcanism on the southern margin of the rise along the Mendocino Fracture Zone, tectonism and volcanism about 85 Ma that resulted in a major regional unconformity (reflector C), and another period of tectonism and volcanism between 65 and 43 Ma that coincided with the formation of the Emperor Seamounts and created structural benches on the western side of the rise. A significant change in the paleoenvironment that apparently occurred around the Paleogene-Neogene boundary (∼25–20 Ma) caused pronounced changes in the depositional environment and resulted in another major regional unconformity (reflector A).

Description: ALs Ergänzung zum IfM-Bericht Nr. 108 wird in dem vorliegenden Bericht für den Benutzer eine Anleitung zu dem Dialogprogramm STASIP (Statistics of Single-Point Moorings) gegeben. Ein vereinfachter Programmlauf stellt die Funktionsweise des Programms dar und vermittelt die wichtigsten Grundlagen. Durch einen weiteren umfassenderen Rechenlauf wird dann die Anwendungsvielfalt des Programms erläutert. Im Anhang befindet sich neben wichtigen Tabellen ein vollständiger Programmausdruck. (AUT)

Description: A subtropical front was observed in the area south and southeast of the Azores during cruises of FS Meteor and FS Poseidon in early 1982. The front has a basically west–east extension, with considerable meandering observed. Meso-scale eddies are found on both sides. The overall flow pattern corresponds to earlier results on geopotential differences in the upper northeast Atlantic, but the baroclinic transport of the order of 107 m3 s−1 is found to be concentrated in a 60-km wide jet. We suggest here that the current band is part of the gyre circulation, resulting from a branching of the North Atlantic Current.

Description: In dieser Arbeit wird das Bewegungsverhalten von Einpunktverankerungen mit Hilfe eines Rechenprogramms untersucht, das zunächst von D. A. Moller an der Woods Hole Oceanographic Institution entwickelt worden war und hier auf Verankerungen des Instituts für Meereskunde Kiel angepaßt wurde. Zunächst werden fünf Messanordnungen in der Ruhelage beschrieben, wobei Stromlosigkeit vorausgesetzt wird. Anschließend wird für sechs vereinfachte Stromprofile die Form dieser Verankerungen berechnet. Mit einfachen Stromprofilen ist es möglich, je nach Stabilität der Verankerung Abtauchtiefen von mehr als 350 m zu erzeugen. Bei diesen hypothetischen Stromprofilen treten Horizontalauslenkungen der oberen Komponente von 1600 m und mehr bei einer Länge der Verankerung von etwa 5000 m auf. Nach Abschätzung des grundsätzlichen Verhaltens werden aktuelle gemessene Daten der Stromgeschwindigkeit gemittelt. Hiermit wird die Form der Verankerung berechnet, um die Wirkung wahrer Stromprofile auf diese Einpunktverankerungen beurteilen zu können. Das Verhalten der NEADS-Verankerungen wird bei allen Stromlagen gut reproduziert, jedoch mussten wegen mangelnder Überdeckung des Tiefenbereichs durch Messgeräte einige Stromprofile durch Interpolation bzw Extrapolation ergänzt werden. Die JASIN-Verankerung lasst sich nur bei geringen Stromgeschwindigkeiten hinreichend gut berechnen, während in Phasen mit starkem Strom der Fehler groß ist. Dies ist unter anderem auf eine zusätzliche Markierungsboje an der Oberfläche zurückzuführen. Zum Abschluß werden einige Hinweise zur Sensitivität des Simulationsprogramms auf bestimmte Verankerungsparameter gegeben, wobei der Reckberechnung von Perlonseil, der Genauigkeit des Stromprofils und der Bestimmung der verwendeten Auftriebe und Gewichte erhöhte Bedeutung zukommen. (AUT)

Description: Circumpolar surface waters dominate the circulation of the Southern Ocean and sustain one of the ocean's largest standing stocks of biomass thereby producing a significant output of biogenic components, mainly diatoms, to the bottom sediments. Generally transit of biogenic matter from the sea surface to the sea floor affects nutrient regeneration fuels benthic life and transfers signals to the sediment record1–5. Reliable quantification of the relationship between biological production, fractionation of skeletal and tissue components and bottom sediment accumulation depends on direct vertical flux measurements from sediment trap deployments6–9, which have proved to be most scientifically productive10–13. We now present data on vertical mass fluxes from the Southern Ocean and evidence for strong biogeochemical fractionation between organic carbon-, nitrogen- and phosphorus-containing compounds, siliceous and calcareous skeletal remains, and refractory aluminosilicates.

Description: The distribution of 234Th, 230Th, and 228Th between dissolved and particulate forms was determined in 17 seawater samples from the Guatemala and Panama basins. Sampling was carried out in situ with battery-powered, submersible pumping systems in which the seawater first passed through a Nuclepore filter (1.0-μm pore size) and then through a cartridge packed with Nitex netting that was impregnated with MnO2 to scavenge the dissolved Th isotopes. Natural 234Th was used as the tracer for monitoring the efficiency of scavenging. For all three isotopes, most of the activity was found in the dissolved form. On the average 4% of the 234Th, 15% of the 228Th, and 17% of the 230Th occurred in the particulate form, though the percentages were found to be strongly dependent on particle concentration. These distributions are not consistent with chemical scavenging models that assume irreversible uptake of Th on particle surfaces. The results can be explained, however, if continuous exchange of Th isotopes between seawater and the particle surfaces is assumed. Vertical profiles of both particulate and dissolved 230Th show increasing concentrations with depth, as required by the assumption of reversible exchange. Some of the dissolved 230Th profiles, however, show a reversal of this trend near the bottom, indicating accelerated scavenging near the water/sediment interface. Kinetics of both adsorption and desorption can be examined if at least two Th isotopes are measured in the same samples. Results show that reaction times are short (a few months) compared to the residence time of suspended matter in the deep ocean (several years), indicating that particles suspended in the deep sea are close to equilibrium with respect to exchange of metals at their surfaces.

Description: During a 10-year study more than 2,000 phytoplankton samples were collected from the entire coast of Peru and analyzed. In general, diatoms were the most abundant group of organisms in all seasons. Predominant species were Rhizosolenia delicatula, Skeletonema costatum Thalassiosira subtilis, Thalassionema nitzschioides and several species of the genus Chaetooeros. Dinoflagellates and flagellates were observed frequently during summer. The mean distribution of the phytoplankton concentration during the 10 years shows the existence of several centers with higher cell densities along the coast, coinciding with the areas of more intense and persistent upwelling. Four major centers have been identified: Pimentel (˜6°S), Chimbote (˜9°S), Callao (˜12°S), and Tambo de Mora-Pisco (˜15°S); and two minor centers, Talara (˜4°S) and Ilo (˜17°S). The relative importance of each center seems to change according to the season. The highest phytoplankton concentration tended to be in the northern part of the coast during fall and winter and in the south through spring and summer.

Description: There has been concern about recent temperature trends and the future effects of CO2 concentrations in the atmosphere1,2; but instrumental records only cover a few decades to a few centuries and it is essential that proxy data sources, such as pollen spectra from peats and lake sediments, be carefully interpreted as climate records. Several workers have shown statistically significant associations between the modern pollen rain and climatic parameters, an approach that by-passes the recognition of pollen/vegetation units. Statistically defined equations that associate abiotic and biotic elements are called transfer functions. We report here on the application of transfer function equations to nine middle and late Holocene peat and lake sediment sequences from northern Canada (Fig. 1).

Description: Die 72. Reise der FS Poseidon fand zwischen dem 9. und 13. März 1981 im Skagerrak statt.

Description: OceanRep OceanRep Home Contact Quick Search Simple Search Advanced Search Browse Author Research division Document type Year Course of Study Latest Peer-reviewed Articles All About us GEOMAR Library Open Access Policies Statements Help FAQs Statistics Directions | Contact | Sitemap | Imprint Zur Kinematik eines stochastischen Feldes interner Wellen in einer Scherströmung. Logged in as Barbara Schmidt Manage depositsManage recordsManage shelvesProfileSaved searchesReviewAdminLogout - Tools Peters, Hartmut (1981) Zur Kinematik eines stochastischen Feldes interner Wellen in einer Scherströmung. (Doctoral thesis/PhD), Christian-Albrechts-Universität Kiel, Kiel, Germany, 118 pp. [img] Text Diss. 1981 Peters, H.pdf - Published Version Restricted to Registered users only Download (7Mb) Abstract Für die im Atlantik im Bereich des Äquatorialen Gegenstroms während GATE beobachtete mittlere Schichtung und Scherströmung werden vertikale Eigenschwingungen (Moden) und Dispersionskurven hochfrequenter (0.3 bis 15 cph) interner Wellen berechnet. Ein spektrales Modell der Kinematik freier, linearer interner Wellen wird durch die stochastische Überlagerung so gewonnener Moden erzeugt. Modellrechnungen werden zu Vergleichs- und Testzwecken für einfache Grundzustände (N 2 = const.; u = const.) durchgeführt. Die den Verhältnissen während GATE entsprechenden Rechnungen ergeben folgende Resultate: In den Energiespektren wird eine Schulter bei Frequenzen zwischen 1.5 und 4 cph beobachtet, die einen nicht unbeträchtlichen Teil der Gesamtenergie des Wellenfeldes repräsentiert. Diese Schulter kann im wesentlichen nicht durch kinematische Effekte erklärt werden, sie muß dynamische Ursachen haben. Im Frequenzbereich 1.5 bis 4 cph wird das Wellenfeld praktisch ausschließlich von der ersten Mode beherrscht. Nach den Beobachtungen sind die Wellen überwiegend gegen die mittlere Strömung gerichtet. Zur Erklärung dessen müssen sowohl dynamische als auch kinematische Effekte herangezogen werden. Das beobachtete Maximum der Kohärenz zwischen Strömung in der Deckschicht und Temperatur in der Sprungschicht zwischen 1. 5 und 4 cph ist prinzipiell der Kinematik des Systems zuzuschreiben. Die Skalen des Wellenzahlspektrums, die sich aus der Anpassung des Modells an die Daten ergeben, sind derart, daß nur ein Teil der Anisotropie des Systems von Moden und Dispersionskurven wirksam wird. Die Vertikalstruktur der beobachteten Strömungsfluktuationen kann mit dem Modell nicht vollständig beschrieben werden. Das Modell wird kritisch diskutiert.

Description: Analysis of aeolo-marine dust deposits in the subtropical eastern Atlantic enables the strength of the major wind patterns during the late Quaternary to be evaluated and gives an insight into the climate of North Africa.

Description: Three arrays of ocean bottom seismographs have been deployed to study the seismicity at the northern end of the Juan de Fuca ridge system off western Canada. Nearly 100 events were located with estimated accuracies generally better than ±10 km, all lying on or near the en echalon ridge-transform fault plate boundaries as defined in this area by the magnetic anomalies, the seafloor morphology and by other geophysical data. The depths of 12 events were determined to lie between 2 and 6 km below the top of the crust. The seismograms exhibit clear P and S wave arrivals along with phases that involve P to S and sometimes S to P conversion probably at the base of the sediments beneath the instruments. The event magnitudes have been estimated from signal duration using four calibration events that were well recorded by a land station. The magnitude estimates permit the determination of rough magnitude-frequency of occurrence relations over the magnitude range of 1 to 3 that are in surprisingly good agreement with the recurrence relations for the area at larger magnitudes from 75 years of land station data. The mean P wave velocity in the uppermost mantle from the earthquake data recorded by the sea floor arrays is 7.6 km s-1 and the mean Vp/Vs ratio is 1.71 or a Poisson's ratio of 0.24.

Description: Frequent collections were made of the marine planktonic copepod Temora longicornis and a series of measurements made to determine the level of nitrogen excretion in this copepod. An algal diet consisting of the marine diatoms Skeletonema and Thalassiosira labelled with 14C was provided in the laboratory. Both excreted ammonia nitrogen and amino nitrogen were measured, as was the total nitrogen in the copepods. The copepods were kept for a maximum of one day and excretion measured one hour after feeding. Oxygen consumption was measured as an indicator of metabolic rate and as a basis for calculations of the O:N ratio and estimations of the efficiency of nitrogen utilisation.

Description: Uptake data of seven sugars (mono- and disaccharides) were used to calculate DOC-turnover and microbial biomass production. The sugars investigated in this study represent 1-2% of the DOC and up to30 % of the free dissolved carbohydrates. The uptake measurements were not based on a kinetic approach. Uniformly labelled 14C-carbohydrates were added to the samples, the concentrations reaching maximally 10% of the corresponding natural substrate concentration. Taking the natural substrate concentration into account, it is possible to calculate the actual uptake rates, turnover times and microbial C-production. An investigation in the Kiel Fjord during 1978/79 shows turnover times for glucose between 1.7 and 600 hours. The microbial biomass production varies between 0.01 and 10 μg C l-1 h-1, i.e. 0.2 - 83% of the primary production. The ratio between incorporation and gross uptake is between 0.62 and 0.95, which supports the assumption that free dissolved carbohydrates are biochemically wellutilized substrates. The relation to exudates is discussed.

Description: In vitro and in situ several macrobenthic species were found to show highest uptake rates of amino acids at low temperatures of 0°-10° C. The rates decreased at a higher temperature of 15° C which favoured the activity and the development of microorganisms. However, the significance of competitive microorganisms was less striking in the in situ experiments than under laboratory conditions. Phenylalanine was most readily taken up although "aufwuchs" of Fucus serratus and Gammarus sp. was found to show primary uptake of aspartic acid. Arthropods were also able to take up dissolved amino acids but in much lower quantities than molluscs and polychaetes. Dissolved amino acids in the water column hardly penetrated the sediment if this was covered by a layer of detritus.

Description: The primary production, quantity and molecular weight distribution of DOC released by phytoplankton, and the subsequent utilization and transformation of these compounds by bacteria in an estuary was studied. High primary production rate and DOC release was observed. The amount and composition of DOC released by phytoplankton aried with time and changing algal population. Low molecular weight products with MW less than 500, fraction with MW 10000 - 30000, and high molecular weightcompounds greater than 300000 dominated in the algal DOC. Bacteria utilized a significant portion of released DOC. The role of bacteria in the transformation of released DOC by algae is discussed.

Description: Field manipulative cage experiments were performed on an unvegetated shallow water mudflat in the eutrophicated inner Oslo fjord. Exclosure and enclosure cages each covering an area of 0.6 m2, were maintained on the mudflat to protect infauna from epibenthic macropredators in general and for exposing the infauna to different densities of the common goby, Pomatoschistus microps, a common predator in the area. Predation effects were determined by comparing faunal composition and abundance inside and outside the cages after 2 1/2 months. Irrespective of the number of gobies in the cages only minor differences in faunal composition and abundance were found between cage and control. lt is therefore concluded that epibenthic macropredators in general and P. microps in particular do not crop infauna to an extent sufficient to alter faunal composition and to reduce abundance discernibly.

Description: During the Second German Antarctic Expedition 24 stations were visited from Januarv to February 1978 between Bellinghausen Sea and South Georgia. Samples were taken for the determination of phytoplankton composition and biomass as well as for protozooplankton biomass. Primary productivity was measured as 14C-uptake for different size classes of the phytoplankton population (〈 20, 20-100 and 100-300 μm). Remarkable was the distribution of biomass and primary production within the different phytoplankton size classes. At nearly all stations the major part of the, biomass consisted of nanoplankton forms smaller than 20 μm which were responsible for about 90 % of the production. These tiny organisms were either diatoms (centric or pennate forms), μ-flagellates or dinoflagellates, thus representing the main phytoplankton groups. Protozooplankton cells were found at all stations, their biomass averaged about 16% of the phytoplanktion biomass. The obvious importance of nanoplankton forms as a food supplier for the krill (Euphausia superba) as well as the importance of protozooplankton as a food source and a food competitor for the krill during the Australian autumn are discussed.

Description: A study on the macroplankton community in Kosterfjorden, Western Sweden, is used to introduce a term called Index of population energy-flow, lpef. This term is defined as the ratio between the energy flow (consumption) through a specific population and the flow through the whole trophic level to which the species belongs. For simplicity, the study is restricted to 6 herbivorous and omnivorous species and 7 carnivorous species. Values for the production, respiration, and excretion are calculated from published data and are presented as means for each of the four seasons. On an annual basis between 8 and 52 % of the assimilated energy is bound in production, between 30 and 85% is used in respiration, and between 6 and 32% is excreted. the estimated grazing pressure of the 6 herbivorous/omnivorous species is relatively low compared with the estimated primary production, especially during spring and summer, indicating that most of the primary production goes directly to the benthic community. The copepod Calanus finmarchicus has the highest index of population energy-flow among herbivorous/omnivorous species with an annual mean of 87% and seasonal maximum in autumn (lpef = 96%). The copepod Metridia longa is most important in spring (lpef = 16%) and the three euphausiid species in summer (lpef = 4-5%). Among carnivores the copepod Chiridius armatus has the highest annual mean value (lpef = 43%) with seasonal maximum in spring (lpef = 65%). Small chaetognaths are most important in autumn (lpef = 18%) and the polychaete Tomopteris helgolandica and the trachymedusa Aglantha digitale in winter (lpef = 33 % and 17%, respectively).

Description: Results obtained from short-term (8 h to 24 h intervals) measurements of physical, chemical and biological properties of the 70 m water column from an anchor station in the Bornholm Sea over a 10-day period are presented and discussed. Phytoplankton biomass concentration and production rates indicated that the spring bloom was in progress in this period. The onset of the spring bloom occurred prior to the advent of thermal stratification. Peak growth rates, accompanied by nutrient depletion and biomass accumulation in surface layers, were concomitant with calm weather and a cloudless sky after which a part of the population was observed to sink out of the water column unimpeded by the permanent halocline. Maximum sinking rates of the dominant species, Skeletonema costatum, ranged between 30 to 50 m per day during this event. The development of the spring bloom apparently takes place in a series of events during which periods of low production alternate with periods of high production and rapid sedimentation of parts of the population.

Description: Every fourth hour in 24 h periods measurements were made of temperature, salinity, plant nutrients, incident radiation at three m depth, sub-surface light extinction, chlorophyll a, phaeophytin, particulate carbon and nitrogen, cell counts, zooplankton dry weight biomass, in situ primary production (14C), incubator carbon assimilation (14C), heterotrophic activity (14C glucose assimilation), and horizontal variation in chlorophyll a over one nautical mile. The marked variations in all parameters were probably generated by the combined effects of wind-driven circulation of water masses in the fjord and phytoplankton patches. This study stresses the presence of spatial and temporal changes in fjords, and that data conducted from one or few stations should be interpreted with care.

Description: Aspects of the inter-relationship of krill Sound Scattering Layers (SSLs) and fish were examined in Ullsfjorden and Øksfjorden, northern Norway from 2 - 8 February 1980. Diel changes in the depth distribution and biomass of krill (Euphausiacea) were compared with the depth distribution and abundance of gadoid fish using a pelagic capelin trawl, 38 and 120 kHz echosounders, and a digital echointegrator. Krill underwent vertical migrations from the surface at night to the fjord bottom at mid-day. A significant power curve relationship was found when catches of krill in the pelagic trawl (l·trawl h-1) were compared with volume backscattering (dB m-3) at 120 kHz, indicating that krill biomass can be reliably estimated using acoustic techniques. Krill were the dominant food item of fish caught with the pelagic trawl in the SSLs. Fish were nevertheless rare in these krill SSLs; the majority congregated under them, probably feeding extensively at their periphery. Interactions between krill and pelagic feeding gadoids in north Norwegian fjords are examined.

Description: The early summer dynamics of major zooplankton populations in Helgoland Bight are discussed on the basis of the GILLBRICHT extension of LIEBIG's law of the minimum. On the basis of monofactorial control of population dynamics, copepod decline in June is caused by predation of Pleurobrachia pileus, phytoplankton never being at levels which would starve copepods. Copepod recovery is correlated with the control of Pleurobrachia pileus by Beroe gracilis, an exclusive predator on this tentaculate ctenophore. By controlling copepods before they can seriously deteriorate the phytoplankton standing stock, high phytoplankton summer levels are possible which characterize the rich ecosystem of Helgoland Bight.

Description: The behaviour and distribution of Palaemon debilis Dana was studied in mangrove lagoons along the east coast of Sinai. Food intake and growth of this prawn were measured in the laboratory and compared with the related Atlantic species Palaemon elegans Rathke, occuring in a saltwater fishpond at Elat. Daily food intake was similar in both species and correlated with their metabolic weight. By feeding groups of prawns different rations of prawnmeat during fourteen days the daily maintenance ration was estimated as approximately 14 percent of the metabolic dry weight while the net food conversion was estimated as 0.4. The role of Palaemon debilis in the mangrove toodweb is discussed.

Description: In situ enrichment bioassays were performed during the summers of 1978 and 1979 in the Falsterbo Channel, south Baltic Sea. Phosphorus and/or nitrogen was added daily for up to two weeks to 200 l polyethylene bags with unfiltered surface water. Additions of nitrogen or nitrogen plus phosphorus invariably increased the biomass and 14C fixation of phytoplankton. Phosphorus additions had no such effects. Phytoplankton species which reacted most strongly to the enrichment were Aphanothece sp., Nodularia spumigena, Skeletonema costatum, Nitzschia closterium, Chaetoceros wighami and Oocystis sp. The mean C/Chl a quotient was around 70 for chlorophyll a values below 6 mg· m-3 but decreased to about 30 for chlorophyll a values above 10.

Description: Energy flow and material cycling in aquatic environments can be conceptualized in terms of food webs, linking various taxonomic or functional biological compartments and their physical environment. Interpretation of empirical data and finally a functional understanding of the system studied requires a high degree of abstraction and aggregation. The complexity and variability of environmental systems, the scarcity of appropriate observations and experiments, and the lack of a weil established theoretical background make it difficult to test any possible conceptualization, or hypothesis, describing a given system. A formal approach to hypothesis testing, based on numerical simulation, which explicitly considers the above constraints, is proposed. Based on a data set from the North Sea, a series of hypotheses on the structural relations and the dynamic function of the pelagic food web is formulated in terms of numerical models. Hypotheses of various degrees of aggregation and abstraction are tested by comparing singular statements (predictions) deduced from the proposed hypotheses (the models) with the observations. The basic processes of primary production, consumption, and remineralization, driven by light, temperature, and advection/diffusion, are described in systems models ranging in complexity from two compartments to many compartments and species groups. With each of the proposed models, a yearly cycle of the systems behavior is si mulated. The comparative analysis of the response of each of the models allows conclusions to be drawn on the adequacy of the alternative hypotheses. This analysis also allows one to reject inadequate constructs, and provides some guidance on how to improve a certain hypothesis, even in the presence of a high degree of uncertainty.

Description: Phagocytosis as a means of heterotrophic nutrition in dinoflagellates, mainly in nonthecate forms devoid of photosynthetic pigments, is described on the basis of a year of observations at two fixed stations and other records from the natural habitat. The phagocytosed inclusions in the cell cytoplasm may show the remnants of the prey organisms in various stages of digestion as distinct from food vacuoles which are normal products of cell metabolism. Most of the larger phagotrophic dinoflagellates, such as Noctiluca miliaris, Polykrikos kofoidii and Gyrodinium spp., were recorded chiefly at the Secchi disk depth in the preserved samples. Among the more fragile nonthecates which were recorded and observed, mainly in live samples, many specimens showed phagotrophic inclusions. The role of these holozoic dinoflagellates in the pelagic ecosystem is discussed.

Description: The kinetics of phytoplankton extracellular release and the compositlon of these photoassimilated products that are excreted are not weil understood, especially in natural populations in which algal excretion and bacterial utilization occur simultaneously. Photoassimilated extracellular products represent an important input of DOC in aquatic ecosystems, a considerable fraction of which is taken up by heterotrophic bacteria. Experiments have shown that extracellular products are assimilated and respired with high efficiency in marine environments. Heterotrophie bacteria seem to play an active role in the regulation and transformation of phytoplankton extracellular products into particulate matter in the marine photic zone.

Description: The ISIS in situ incubator was used to evaluate the dynamics of a phytoplankton bloom in the Kattegat in late October 1979. The nutrient status of the water column indicated a typical fall regenerative situation with relatively high concentrations of ammonium and phosphate and only low concentrations of nitrate. The photic zone was well mixed during the bloom due to preceding rough weather. Clear, sunny and calm conditions prevailed the day prior to and during the bloom. Primary production was measured at four depths and amounted to 90.4 mg C m-2 h-1 integrated from the surface to 12 m. The highest fixation rate occurred at 1 m depth and was 16.4 mg C m-3 h-1. The productivity index was 3.7 mg C (mg chlorophyll a)-1 h-1 at 1 m and 5.3 mg C (mg chlorophyll a)-1 h-1 at 4 m depth. The light response relationship showed light saturation at about 3.8·1023 quanta m-2 h-1. It is concluded that primary production during this experiment was controlled by a combination of excess light energy and temperature but not by nutrient limitation.

Description: Three large plastic enclosures (3-4 m3) were anchored in the outer harbour of Helgoland (German Bight) and filled with natural seawater which was filtered free of algae. The enclosed water bodies were enriched with inorganic nutrients and inoculated with the diatom Thalassiosira rotula. During the growth of the algae diurnal changes in concentration of dissolved free amino acids (DFAA) occurred. The periodic concentration changes of individual amino acids with a low carbon to nitrogen ratio showed significant interrelationships with the partly synchronous devisions of the diatoms. From the exponential to the stationary phase the carbon to nitrogen ratio of DFAA shifted to higher values pointing at an adaptation of the organisms to the decreasing inorganic nitrogen source. During the bloom amino acids relatively rich in nitrogen were mainly excreted but by the end of the growth amino acids with a higher carbon content predominated. At phases of high photosynthetic activity the organisms probably reduced the high osmotic pressure by exudation of DFAA.

Description: Phenotypes, distribution and behaviour of Mesodinium rubrum (Lohmann) were studied in the stagnant basin lnre Verkviken (salinity about 6‰) on Åland, SW Finland. The organism varied in lenght from 15 to about 50 μm. The number of cirri varied greatly (33-85) and so did the number of chloroplasts (a few to more than 50). Surface maxima (red water) coinciding with chlorophyll a and productivity maxima were observed in October. Living specimens rich in starch were, however, also found down at 17 m in almost oxygen-free water. The swimming speed of Mesodinium rubrum can momentarily exceed 5000 μm s-1. Thus the organism has the potential to migrate vertically and take up nutrients from appreciable depths. The organism is highly phototactic and it is easily concentrated in a light gradient. The photosynthetic rate of enriched samples (artificial red water) was much higher than that of the original water samples. The role of Mesodinium rubrum in the food web is discussed.

Description: The micro-organisms which colonise kelp debris incubated in seawater show a clear succession. The media are first colonised by bacterial cocci and rods which are subsequently replaced by grazing flagellates and ciliates, as weil as amoebae and choanoflagellates in the later stages of the microheterotrophic succession. The biomass of grazing protozoa is generally 10% of that of the bacteria and estimates of consumption of bacteria by microflagellates of 10 μm3 body volume suggest that a mean value of 39 x the body weight may be consumed per day. lt is suggested that filter- and deposit-feeding organisms utilising degrading plant material are likely to use bacteria rather than protozoa as a principal food resource. Estimates of the rate of turnover of sediments and of the water column near to kelp beds support the belief that for optimal utilisation by consumer organisms detritus is recycled at a rate which is slow enough to promote the development of a bacterial population but which is too fast for protzoa to reduce the bacterial population by grazing.

Description: During spring and in summer the digestive enzymes trypsin and amylase of copepodids and adults of Calanus finmarchicus and C. helgolandicus were studied in a Swedish fjord in relation to various parameters of particulate matter. Regulation mechanisms of digestive enzymes varied with stage of development and physiological condition. In the stages studied three types of regulation were found: In copepodid stages Cl/II trypsin remained constant at a rather high activity irrespective of variations in amylase activity; in CIII-CV and males trypsin and amylase were strongly correlated; in females both enzymes varied independently of each other. Digestive enzymes of CV, females and males of the overwintering generation, were generally very low and did not correlate with any of the food parameters. The digestive enzyme activities were compared with concentrations of chlorophyll a, particulate carbon, nitrogen and carbohydrates at different depths. Amylase of stages CI-CV and adult males and trypsin of CIII-CV and males correlated significantly with carbohydrate concentrations. On the other hand amylase of adult females gave significant correlations with chlorophyll a and carbon. It is suggested that this difference between females and the other stages indicates different food selection.

Description: Copepods are an important link in the marine food web, and, in particular, serve as food for fish larvae. Schizopera elatensis, a marine harpacticoid copepod, was reared in the laboratory, and the effect of various environmental factors, i.e., diet, temperature, salinity and height of water column on its growth was determined. Schizopera elatensis multiplies at a wide range of salinities, 10‰ to 70‰, and temperatures, from at least 18° C to an upper limit of 36° C, with an optimum of 25° C, and grows in high densities (300-400 individuals per ml): the lower the water column, the higher the density. The prospective use of S. elatensis as a live food organism in mariculture is discussed.

Description: 14C and 3H methylamine, ammonium analogues, were used to study the competitive NH4+ uptake by cultured and natural phytoplankton and bacteria populations. The tracer experiments, performed by liquid scintillation techniques and microautoradiography, give evidence of competitive NH4+ uptake by bacteria and phytoplankton in oligotrophic and mesotrophic waters of the Baltic Sea. In eutrophic waters the uptake of the ammonium analogue was low especially for bacteria. Decreasing light intensity increased the methylamine uptake by bacteria compared to phytoplankton. Bacteria, competing with phytoplankton for dissolved ammonia in oligotrophic Baltic water, apparently do not play an important role in nitrogen remineralization. The significance of other decomposers is discussed.

Description: The main studies on phytoplankton ecology carried out in Kiel Bight during the last decades are briefly reviewed. Special emphasis is laid on the hydrographical structure of this transitional area between the Baltic Sea and the North Sea, as it strongly affects the seasonal cycle of phytoplankton standing stock and species succession through vertical stratification and advection processes. Both these hydrographical features prevail during the growth period of phytoplankton and are responsible for large variations in population density and nutrient supply. The seasonal species succession is also influenced by advection. The annual primary production figure of about 150 g C·m-2 approaches the upper limit of values recorded for other parts of the western and southern Baltic. Total irradiation appears to exert the strongest influence on the seasonal cycle of primary production as long as water temperatures are low, giving way in summer to temperature as the determining factor for the production rate.

Description: The fucoid/barnacle system on a moderately exposed shore on the Isle of Man is briefly defined and described. Patella were either continually removed or excluded by fences in various parts of the mosaics on this shore. This tested the influence of their grazing on the different communities. The sequences and rates of algal colonization of the different experimental areas are compared. Diatoms and/or small filamentous algae, followed by larger greens and then Fucus sporelings formed the usual pattern of colonization. Patella grazing has greatest effect in the mid-region of this shore; but it decreases higher and lower down, and on verticals and amongst dense old barnacles.

Description: The population density and standing stock (wet-, dry-, and organic biomass) of copepods, euphausiids, chaetognaths, and total zooplankton were studied from March 1976 to February 1977. Seasonal changes in population density and standing stock were examined with regard to hydrography and phytoplankton standing crop (chlorophyll a) and primary production (14C). The data have been further analysed with respect to the trophic position of the component zooplankters and to the production cycle in Norwegian arctic fjords.

Description: Thioploca constitutes a great portion of the benthic biomass off the Chile-Peru coast. This organism is eaten by the higher organisms and constitutes a major input of organic carbon in the food chain in this region. Thioploca has been an enigma ever since its discovery in 1907 and the prefix "thio" in the genus name has led investigators to believe that hydrogen sulfide is the energy source necessary to synthesize Thioploca biomass. The results of this investigation indicate that methane is the energy and carbon source for the organism. The organism does not use radioactive labeled acetate, glucose, mixture of amino acids, thymine or bicarbonate as demontrated by autoradiography. Since the energy and carbon source is methane, it indicates that Thioploca is a methylotroph. Methane in this area is generated by microbial activity in reduced sediments and from seepage from coal seams that run under the seafloor. Methane, through Thioploca, represents a major new mechanism, other than photosynthesis, to add cellular carbon to the ecosystem oft the Chile-Peru area. Because methane is the energy and carbon source, Thioploca's taxonomic position as weil as its evolutionary position should be re-assessed.

Description: Microbial biomass, concentrations and enzymatic decomposition rates of proteins and carbohydrates were analysed during spring 1980 from a 10 m sediment station in the Kiel Bight. During March, a considerable increase in total organic matter, proteins and carbohydrates was observed, followed by a decrease during April. The accumulation of organic matter in the sediment could be traced back to the breakdown of the algal spring bloom. Activity rates of (α-amylase, ß-D-glucosidase and proteolytic enzymes paralleled the variation pattern in concentrations of carbohydrates and proteins. During the decomposition processes, a drastic shift in the protein to carbohydrate ratio was observed. The dominating part of the enzymes involved in the decomposition of organic material obviously arose from autolysis of the algae cells themselves. After an initial depression, microbial biomass increased, obviously due to the availability of suitable substrates for microbial growth following the decomposition processes.

Description: Data from a series of laboratory and field predation experiments using fish and decapod predators from seagrass beds in the Indian River, Florida, USA, indicated that the density of many of the taxonomic groups of seagrass-associated macrobenthos were related in a negative exponential manner to the total density of decapod crustaceans present. Significant regressions were observed in the laboratory and the field experiments for the Amphipoda, Gastropoda, Bivalvia, Polychaeta, Sipunculida, and Tanaidacea, whereas the lsopoda and Nemertinea showed no such relationships. These data emphasize the fact that simplification of intermediate trophic levels in trophic models is unwarranted and may result in failure to recognize important regulatory pathways for seagrass community structure.