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: From 27 Janua1y to 23 June 1979 R. V. "Meteor" surveyed the central equatorial Atlantic on a section along 22° W from 3° N to 2° S. During the observation period, a hydrographic section down to 600 m was repeated ten times with a continuous "Howaldt-Bathysonde" CTD and a rosette sampler. The station distance was 10 to 15 nm. The water samples were used to recalibrate salinity and to determine oxygen, nutrients and chlorophyll a. An undulating CTD system ("Delphin") was towed on 11 sections. A profiling distance of one to two nautical miles and a profile depth of 90 m was obtained. Five current meter arrays were moored along 22° W between 3° N and 1° S from January to March 1979. In May and June two moorings were installed at 2° N and at the equator. On the buoys measurements of wind speed and direction were obtained. At 43 stations a wire-guided Aanderaa profiling current meter was successfully lowered. Drifting buoy experiments were repeated three times with clusters of 5 to 10 buoys. A fourth experiment took place in 1978 in the Gulf of Guinea. On the way from and to port XBT sections were carried out. The data sets obtained by these instruments are presented in this data report.

Description: Along the Sierra Leone continental shelf edge, bedded rocks, presumably mostly calcareous sandstone, calcarenites and siltstones form exposures up to 10 km long in water depths ranging from 80 to 110 m. These outcrops are found in a 6 km broad zone along the shelf edge; landward they get covered by recent shelf sands. Their apparent strike direction parallds the shelf edge indicating nearly horizontal bedding which locally is interrupted by faulting. On the middle shelf, a terrace is well developed at a water depth of 56 m. Ripples, megaripples, pockmarks 1-5 m in diameter, and canyon-heads form other significant features of the shelf.

Description: The sediments of a 10.67 m long piston core recovered from the Sierra Leone Rise ("Meteor" Core 13519) have been analysed for their paleomagnetic properties. Using detailed demagnetization techniques, the geomagnetic Brunhes/Matuyama boundary could be identified between 9.81 and 9.89 m sub-bottom. This is in excellent agreement with the oxygen isotope stratigraphy by SARNTHEIN et al., this volume. Down to this level, therefore, the average apparent accumulation rate amounts to 13.5 m/m.y. assuming an age of 0.73 m.y. for the reversal boundary (BERGGREN et al. 1983). A second transition in magnetization polarity was recognized between 10.51 and 10.54 m sub-bottom. According to its magnetic signature it was tentatively correlated to the beginning of the Jaramillo event (0.98 m.y.). This would imply that in the lowermost part of the core the apparent accumulation rate decreases to less than 20% of that found in the upper sequences. However, as obviously only a small portion of the Jaramillo event is recorded in the sediment column, a more plausible solution is to keep the overall sedimentation rate about constant by introducing a hiatus of some 2·105 years shortly after the lower Jaramillo/Matuyama reversal boundary. Alternative interpretations are also discussed.

Description: From a 10.7 m long gravity core from the Sierra Leone Rise (5° 39,5' N, 19° 51'W) a detailed oxygen and carbon isotope record of both planktonic and benthonic foraminifera species was obtained extending from the Recent to the Jaramillo event. The analysis yielded six major results. 1. Benthos oxygen isotopes varied by 1.8-2.2‰ from interglacial to glacial times and may indicate a synglacial cooling of North Atlantic Deep Water at 2800 m depth by 1-3° C. 2. Variable anomalies between the benthos and plankton δ18 O record indicate a cooling of sea-surface temperatures (SST) by up to 6° C during some glacial stages. 3. Southerly trade winds and equatorial upwelling may exert the primary control of SST variations, in particular of extreme values of cold and warm stages and of the abrupt character of climate transitions and their leads and lags, and finally, of variable sedimentation rates. 4. The benthos δ13C record correlates well with the flux and preservation of organic matter. 5. A new time scale, CARPOR, was established from the assumption that terrigenous sediment supply was ± constant but CaC03 varied considerably. When applied to the δ18O record, three major and numerous short-term variations of sedimentation rates (0.8 to 4.0 cm/kyr) can be distinguished. 6. The climatic record was modified by bioturbation much more strongly during cold than during warm stages.

Description: Planktonic foraminiferal tests of the spinose species Orbulina universa, of the non-spinose Globorotalia tumida-menardii complex, and of a mixed species assemblage (grain size fraction 200-400 μm) were isolated from Sierra Leone Rise core 13 519-2 and analyzed for free, total, and bound (by difference) amino acids to study the isoleucine epimerization mechanism in fossil foraminiferal tests and to define empirical calibration curves for dating deep-sea sediments over the past 900,000 years. Total isoleucine epimerization curves typically separate into three "linear" segments of decreasing apparent rates with increasing time and exhibit a pronounced "species effect". The degree of epimerization attained at time is considerably lower in 0. universa than in G. tumida-menardii while the mixed species results scatter between the limits delineated by the two monospecific curves. Total allo/iso ratios are closely related to the proportion of free to total isoleucine accumulating in the tests indicating that the rate of hydrolysis of matrix proteins and peptides controls the overall epimerization reaction. The results are consistent with experimental evidence (KRIAUSAKUL & M1TTERER 1978, 1980 a, b) whereupon isoleucine epimerizes at a rapid rate in terminal positions but at slow rates in interior positions as well as in the free state. Notwithstanding free isoleucine exhibits the highest degree of epimerization due to preferential hydrolysis of extensively epimerized terminal isoleucine. Species-specific hydrolysis and epimerization rates are maintained until about 50% of bound isoleucine have been hydrolyzed to the free state corresponding to a total allo/iso ratio of about 0.5. Remaining peptide units appear to be more resistent against hydrolysis and separate species then show the same apparent epimerization rate dominantly controlled by the slow conversion rate in the free state until equilibrium is achieved in Miocene samples under deep-ocean temperature conditions (KING & HARE 1972 a). The degree of epimerization attained at comparable time in separate species will, however, remain different due to different initial rates of hydrolysis. Selective leaching of free isoleucine from the tests results in a lowering of total allo/iso ratios and apparent rate constants when significant amounts have been generated by diagenetic hydrolysis. Comparison with results based on Pacific core V 28-238 (KING & NEVILLE 1977) indicates an inverse relationship between the intensity of surficial carbonate dissolution and post-depositional leaching. Tests deposited under less corrosive conditions (Atlantic core 13519-2) will more significantly deviate from a closed system during diagenesis than those deposited in more corrosive bottom waters (Pacific core V 28-238). Carbonate dissolution removes proteinaceous lamellae from more external shell structures, which otherwise - if preserved during deposition - will preferentially be subject to leaching of free amino acids during diagenesis. This effect may qualify the applicability of empirical epimerization calibration curves to different depositional environments although the general agreement of the epimerization curves obtained for both sites is promising for future research. Identical apparent epimerization rates in G. tumidamenardii tests younger than 120,000 years (when leaching is stiH insignificant) at both Atlantic and Pacific sites are not consistent with the presently different bottom water temperatures in these regions. It is concluded that glacial North Atlantic Deep Water was cooler than at the present at the Sierra Leone Rise.

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: 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: Measurements by CTDs (Multisonde, Bathysonde) and current profilers were carried out onboard the research vessels "Meteor" and "Planet" during the Joint Air-Sea Interaction Project (JASIN) in 1978. Data from these observations are presented in the form of mean distributions with their standard deviations, as time series and as profiles during the "multiship experiments". Selected time series of terms derived from the data are added: current shear, Vaisala frequency and Richardson Number. The text also contains information concerning instrument calibration and data processing.

Description: The three Federal German research vessels "Planet", "Meteor" and "Poseidon" participated in the Second Multiship Experiment during JASIN 1978 as stationary ships with CTD yo-yo profiling. The analysis is concerned mainly with the weakly stratified layer between the seasonal thermocline and the turbulent mixed layer. The thermoclinic structure of a front in that layer and its tidal/inertial displacement is described and is shown to be in accordance with current meter data from the H2 mooring. It is shown that the CTD yo-yos cannot be treated as pure time-series but that the movement of the ships relative to the seabed and relative to the front has to be taken into account. The method of isopycnic analysis was used to eliminate the effect of internal waves. Temporal coordinates can be converted to spatial coordinates allowing for the tidal/inertial movements. Thus high resolution sections through the front can be given. The thermohaline structure is described on density levels in the seasonal thermocline and in the weakly stratified layer above it.

Description: We present field measurements of air-sea gas exchange by the radon deficit method that were carried out during JASIN 1978 (NE Atlantic) and FGGE 1979 (Equatorial Atlantic). Both experiments comprised repeated deficit measurements at mixed position over periods of days or longer, using a previously described precise and fast-acquisition, automatic radon measuring system. The deficit time series exhibit variations that only partly reflect the expected changes in gas transfer. By evaluating averages over each time series we deduce the following average gas transfer velocities (average wind velocity and water temperature in parentheses): JASIN phase 1: 1.6 ± 0.8 mid (at -6 mis, 13 °C) JASIN phase 2: 4.3 ± 1.2 mid (at -8 mis, 13 °C) FGGE: 1.2 ± 0.4 mid (at -5 mis, 28 °C) 0.9 ± 0.4 mid (at -7 mis, 28 °C) 1.5 ± 0.4 mid (at -7 mis, 28 °C) The large difference between the JASIN phase 2 and FGGE values despite quite similar average wind velocity becomes even larger when the values are corrected to a common temperature. Both values are, however, fully compatible with the range of gas transfer velocities observed in laboratory experiments and the conclusion is suggested that their difference is caused by the highly different wind variability in JASIN and FGGE. We conclude that in gas exchange parameterization it is not sufficient to consider wind velocity only. A comparison of our observations with laboratory results outlines the range of variation of air-sea gas transfer velocities with wind velocity and sea state. We also reformulate the radon deficit method, in the light of our observed deficit variations, to account explicitely for non-stationarity and horizontal inhomogeneity in the near-surface radon deficit layer (i.e., mixed-layer and upper thermocline). We show that neglection of non-stationarity and horizontal inhomogeneity in previous radon work introduces considerable uncertainty in deduced gas transfer velocities. We furthermore discuss the observational requirements that have to be met for an adequate exploitation of the radon deficit method, of which an observation area of minimum horizontal inhomogeneity and monitoring of the remaining inhomogeneities are thought to be the most stringent ones.

Description: Data from two current meter moorings and thermosa�linograph records from the Scotia Sea are presented. Results from the first mooring site demonstrate the ex�change of Antarctic Bottom Water between the northern Scotia Sea and the Argentine Basin. The sec�ond current data set illustrates the permanent deep counter current on the continental rise of the southern Drake Passage. Surface temperature and salinity rec�ords describe the position of the Polar Front and the Weddell-Scotia-Confluence during early austral sum�mer 1980/81.

Description: Seven cores from the West-African continental margin in 12-18° N have been investigated by means of a coarse fraction analysis. Four of the seven cores contain allochthonous material: turbidites and debris flow deposits. The source of the allochthonous material is in about 300-600 m water depth. The age of the slide induced debris flow deposits is at the end of oxygen isotope stage 2. One debris flow deposit is covered by a turbidite (core 13211). The turbidites in the deep-sea core 13207 originate from river-influenced sediments from the West-African continental margin, whereas the autochthonous sequences are influenced by volcanic material from the Cape Verde Islands. Particle by particle supply from upper slope areas has been found in all four cores from the continental slope. Current sorting occurs on the submarine diapir (core 89), whereas core 91 on the NW-flanc, 200 m below core 89, has no current sorting, except for stage 1 and parts of stage 5. The current sorting is reflected by parallel variations of median diameters of whole tests and of fragments of planktonic foraminifers, by higher median diameters of foraminifers on top of the diapir, by reduced accumulation rates and increased sand fraction percentages in core 89 compared to core 91. The Late Quarternary climatic history of the West-African near coastal area (12-18° N) has been redrawn (Fig. 10): - in oxygen isotope stage 1 a humid climate is found in 12-18° N (This "humid impression" in 18° N, which is actually an arid area, is due to the poleward directed undercurrent, which transports Senegal river material to the north). - in oxygen isotope stage 2 an arid climate existed in 14-18° N, whereas in 12° N river discharge persisted. But within stage 2 dune formation occurred in 12° N on the (dry) shelf, additionally to fluviatile sediment input. - Older periods are preserved in autochthonous sediments of core 89 and 91, where oxygen stages 3, 5 and 7 (the latter only in core 89 present) show a humid climate (as well as in stage 5 of core 55), interrupted by short arid intervals in core 89, and stage 4 and 6 show an arid climate, interrupted by short humid periods (s. Fig. 10). The allochthonous stage 5 sediment in core 11 also reflects a humid climate. The dissolution of planktonic foraminifers is strongest in the Late Holocene and shows a minimum in the Early Holocene, where also pteropods are preserved. The degree of carbonate dissolution is related mainly to the fine matter content (〈 63 μm) (Fig. 11) whereas water depth is a less decisive factor.

Description: Foraminifera shells from modern sediments document the hydrography of the coastal upwelling region off Northwest-Africa (12-35° N) through the stable isotopic composition of their shells. Oxygen isotopes in planktonic foraminifers reflect sea-surface temperatures (SST) during the main growing season of the different species: Globigerinoides ruber (pink and white) and G. sacculifer delineate the temperatures of the summer, Globorotalia inflata and Pulleniatina obliquiloculata those of the winter. Oxygen isotopes in Globigerina bitlloides document temperature ranges of the upwelling seasons. δ18O values in planktonic foraminifera from plankton hauls resemble those from surface sediment samples, if the time of the plankton collection is identical with that of the main growing season of the species. The combined isotopic record of G. ruber (white) and G. inflata clearly reveals the latitudinal variations of the annual mean SST. The deviation of the δ18O values from both species from their common mean is a scale for the seasonality, i.e. the maximum temperature range within one year. Thus in the summer upwelling region (north of 25° N) seasonality is relatively low, while it becomes high in the winter upwelling region south of 20° N. Furthermore, the winter upwelling region is characterized by relatively high δ18O values - indicating low temperatures - in G. bulloides, the region of summer upwelling by relatively low δ18O values compared with the constructed annual mean SST. Generally, carbon isotopes from plankton hauls coincide with those from sediment surface samples. The encrichment of 13C isotopes in foraminifers from areas with high primary production can be caused by the removal of 12C from the total dissolved inorganic carbon during phytoplankton blooms. It is found thatcarbon isotopes from plankton hauls off Northwest-Africa are relatively enriched in 13C compared with samples from the western Atlantic Ocean. Also shells of G. ruber (pink and white) from upwelling regions are enriched in the heavy isotope compared with regions without upwelling. In the sediment, the enrichment of 13C due to high primary production can only be seen in G. bulloides from the high fertile upwelling region south of 20° N. North of this latitude values are relatively low. An enrichment of 12C is observed in shells of G. rnber (pink), G. inflata and P. obliquiloculata from summer-, winter- and perennial upwelling regions respectively. Northern water masses can be distinguished from their southern counterparts by relatively high oxygen and carbon values in the "living" (= stained) benthic foraminifera Uvigerina sp. and Hoeglundina elegans. A tongue of Mediterranean Outflow Water can be identified far to the south (20° N) by 13C-enriched shells of these benthic foraminifera. A zone of erosion (15-25° N, 300-600 m) with a subrecent sediment surface can be mapped with the help of oxygen isotopes in "dead" benthic specimens. Comparison of δ18O values in aragonitic and calcitic benthic foraminifers does not show a differential influence of temperature on the isotopic composition in the carbonate. However, carbon isotopes reflect slight differences under the influence of temperature.

Description: In samples from the Iberian Basin and off Cape Blanc, dredged from below 2000 m, 10 species of ophiuroids were found, viz. Ophioscolex sp., Ophiambix meteoris, Amphioplus verrilli, Amphilepis sp., Ophiochiton ternispinus, Amphiophiura convexa, Ophiocten latens, Ophiura ljungmani, Ophiomusium lymani, and Ophiosphalma armigerum. The distribution of the species found is summarized. The descriptions of Amphioplus verrilli, Ophiochiton ternispinus, Ophiomusium lymani, and Ophiosphalma armigerum are extended. Silax pulvinus is supposed to be synonymous with Amphioplus verrilli. The genus Silax is withdrawn. Most of the genera and many of the species are cosrnopolitans. The ophiuroids found have no morphological characteristics distinguishing them as deep-sea forms.

Description: A general study of structure, biomass, and dynamic estimates on meiofauna was carried out during PREFLEX (1975) and FLEX (1976), in 117-141 m water depth. On the basis of these data an attempt was made to estimate meiofauna production, and this is discussed in relation to the energy input from the spring phytoplankton bloom. Sampling was performed at five stations, but only the stations 1, 4, and 5 were covered by a complete series from August 1975 to July 1976. At each station, from four replicate box core samples, two were withdrawn to study the abundance, distribution, and biomass of meiofauna, the content of chloroplastic pigment equivalents (CPE), and chemical and grain size analyses. At all stations grain size feil in the range of fine sand having median diameters (MD) of 〈125 μm. From Station 1 to 5 an increase in MD was observed. Highest values of CPE (7.81 μg ml-1) and organic matter (4.7%) were obtained in June and July (1976)/August (1975), respectively. Meiofauna abundance was fairly uniform at all stations examined. Station 1 displayed maximal numbers during the whole investigation period. The abundance per 100 cm2 varied between 15,550 and 34,900 organisms. All meiofauna studied both in total and as separate taxa showed annual cycles of abundance. Low abundance values were recorded during early summer, and maximum values during winter. High numbers of Foraminifera were obtained for August 1975 (9,460 per 100 cm2) and July 1976 (9,710 per 100 cm2). From December to June the values decreased from 3,280 to 1,030 per 100 cm2. At station 1 maximum values of meiofauna biomass were recorded ranging from 1.5 to 2.7 g DWT m-2. The mean meiofauna dry weight amounted to 2.1 g DWT m-2. Based on minimum production, the P/B ratio for the area of Station 1 might have a mean of 1.4. Taking into consideration generation times we believe that a turnover ratio of 2 is a conservative value for the Fladen Ground meiofauna. The annual production would amount to 4.2 g DWT m-2 yr-1. This is 27.5% of the energy supply during the spring phytoplankton bloom, which is channelled into the meiofauna. The hypothesis is put forward that the energetic strategy of deep offshore meiofauna differs distinctively from that of shallow inshore meiofauna. While the shallow inshore meiofauna show a relatively fast response to organic matter input, the deep offshore meiofauna reacts much more slowly, the food energy consumption seems to be spread out over a longer period.

Description: A general study of structure, biomass estimates and dynamics on the macrofauna was carried out in August 1975 and March 1976 during PREFLEX (1975) and FLEX (1976), the Fladen Ground Experiment. On the basis of these data an attempt was made to estimate macrobenthic production expressed as minimum production (MP). The macrobenthic production is discussed together with meiobenthic annual production (FAUBEL, HARTWIG & THIEL 1983) and with indirectly estimated microbenthic production in relation to an energy input from the water column of about 25g C m-2 year-1 (STEELE 1974). From the production estimates of the three benthic components a rough energy budget is proposed. Sampling was performed at five Stations for endofauna twice during the time of investigation and for epifauna once. At each station two replicate box core samples (30 X 20 cm) were taken for endofauna. Epifauna was sampled with an Agassiz trawl once at each Station. The total numbers of endofauna increased from station l to 5. This was valid as well for August 1975 (4,233-12,166 individuals per m2 and 10 cm sediment depth) as for March 1976 (1,008-2,925 individuals). The polychaetes were the dominant organisms with a share of 33 to 62%. The densities for the endofauna decreased from August 1975 to March 1976 by a mean factor of 2.8. Abundances of epifauna amounted to values between 11 and 102 individuals per 1000 m2. The biomass dry weights (DWT) for macrobenthic endofauna varied between 0.97g DWT m-2 and 6.42g DWT m-2 in August 1975 and between 0.27g DWT m-2 and 2.64g DWT m-2 in March 1976. The mean amounted to 1.74g DWT m-2. Dry weights of epifauna biomass gave values between 4.9 and 83.1g DWT, 1000 m-2. The minimum production for the total macro-endofauna at Fladen Ground amounted to 1.43g DWT m-2 yr-1 or 0.82g C m-2 yr-1. This resulted in a minimum turnover rate (P/B) of 0.8. The share produced by the polychaetes amounted to 1.06g DWT m-2 yr-1 or 74%.

Description: Based on more than 1800 neuston tows, the ranges and mean abundances per area of 10 taxa of beloniform fish are calculated. The distributional patterns of fry of most oceanic taxa are a consequence of both surface temperatures and direction of currents. Oxyporhamphus microptems has a strictly tropical distribution; in the centre of its distribution the mean abundance reaches 10-50 ind./1000 m2. Nanichthys simulans occurs polewards of 0. micropterus, mainly within the great warm circulation systems. Scomberesox saurus has a bipolar subtropical-temperate distribution with seasonal shift of the boundaries, and a general abundance of 30-40 ind./1000 m2, though in subtropical frontal zones values above 100 ind./1000 m2 are common. Exocoetus volitans covers the warmer parts of the Atlantic, but has two antiequatorial belts of maximum abundance within the tropics (25-35 ind./1000 m2). The other exocoetid taxa have similar poleward boundaries as E. volitans. E. obtusirostris and genus Cypselurus average 1.5 ind./1000 m2, whilst Prognichthys gibbifrons, Danichthys rondeletii and genus Hirundichthys have mean abundances of an order of 0.5 ind./1000 m2. Belone svetovidovi is strictly neritic, and shows great regional differences of abundance off NW Africa.

Description: Macro- and meiobenthic abundance and biomass as well as metabolic activity (respiration, ETS activity) have been studied along a transect ranging from 130 to 3000 m water depth off northern Morocco (35° N) during "Meteor" cruise No. 53 (1980). The distribution of chloroplastic pigment concentration (chlorophyll a, pheophytins) in the sediment has been investigated as a measure of sedimented primary organic matter. High chloroplastic pigment concentrations were found on the shelf and around the shelf break, but values declined rapidly between 200 and 600 m depth. Below 1200 m pigment concentrations remained at a relatively uniform low level. Macrobenthic abundance and biomass (wet weight) decreased with increasing water depth and with distance from the shore. Significant changes occurred between the shelf and upper slope and below 2000 m depth. Meiobenthic abundance and biomass (ash free dry weight) followed the same general pattern, but changes were found below 400 and 800 m depth. In the depth range of 1200 to 3000 m values differ only slightly. Meiofauna abundance and biomass show a good correlation with the sedimentary chloroplastic pigment concentrations. Respiratory activity of sediment cores, measured by a shipboard technique at ambient temperatures, decreased with water depth and shows a good correlation with the pigment concentrations. ETS activity was highest on the shelf and decreased with water depth, with significant changes between 200 and 400 m, and below 1200 m depth, respectively. Activity was generally highest in the top 5 cm of the sediment and was measurable, at all Stations, down to 15 cm sediment depth. Shelf and upper slope stations exhibited a vertical distribution pattern of ETS activity in the sediment column, different from that of deeper Stations. The importance of biological activity measurements as an estimate of productivity is discussed. To prove the thesis that differences in benthic abundance, biomass and activity reflect differences in pelagic surface primary production, in the case of the NW-African coast caused by different upwelling intensities, the values from 35° N were compared with data from 21° N (permanent upwelling activity) and 17° N (ca. 9 months upwelling per year). On the shelf and upper slope (〈 500 m) hydrographical conditions (currents, internal waves) influence the deposition of organic matter and cause a biomass minimum between 200 and 400 m depth in some regions. But, in general, macrobenthic abundance and biomass increases with enhanced upwelling activity and reaches a maximum in the area off Cape Blanc (21° N). On the shelf and in the shelf break region meiofauna densities are higher at 35° N in comparison to 21° N; but in contrast to the decreasing meiofauna abundance with increasing water depth at 35° N, an abundance maximum between 400 and 1200 m depth is formed in the Cape Blanc region; this maximum coincides with the maximum of sedimenta1y chloroplastic pigment equivalents. The comparison of ETS activities between 35° N and 21° N shows on the shelf activity at 21° N is up to 14 times higher and on the slope 4-9 times higher, which demonstrates that benthic activity responds to the surface productivity regime.

Description: 7 new Harpacticoidea species and the female of a known species of the family Cletodidae (Crustacea, Copepoda) new to science are dealt with in this paper. Heteropsyllus serratus n. sp. Mesocletodes trisetosa n. sp. Mesocletodes parabodini n. sp. Mesocletodes variabilis n. sp. Paranannop11s plumosus n. sp. Paranannopus langi WELLS, 1965 ♀ Metahuntemannia pseudomagniceps n. sp. Metahuntemannia atlantica n. sp. As far as possible the species relationships within each genus are discussed. All species were collected at 500 m depth on the Iceland-Faroer-Ridge.

Description: In the present paper results of taxonomic investigations on 1137 specimens of Cyllopus magellanicus DANA 1853 and of 730 specimens of Cyllopus lucasii BATE 1862 are reported. A brief diagnosis and key are given for the genus and the species. For the first time larvae of the pantochelis stage of these species are described. The habitus of the larvae are very similar, small differences were found on the structures of the pereopod 3-6. Due to special morphological similarities it is concluded that the larvae of both species display a parasitic way of life like Vibilia. The distribution of the species in the Antarctic Ocean is circumpolar: C. magellanicus occurs probably only within the West Wind Drift while C. lucasii was found within both the West and the East Wind Drift. Remarkable is the occurrence of a great number of males of C. magellanicus in the uppermost layer (30-0 cm depth), meanwhile the females of this species were found only in deeper layers.

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: 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: 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: Psephitic particles in the region of the Iceland-Faeroe-Ridge have been transported and deposited by means of a complex interplay of glacier movements and drifting icebergs. The composition of the particle association is controlled by the sedimentation of basaltic rock particles derived from the ridge itself and, in addition to that and in southern parts of the ridge, from the Faeroe Islands, the Faeroe-Bank and the Bill Baileys-Bank. Besides, there are crystalline and sedimentary dropstones showing a very varied petrography and a wide range of particle sizes. Their percentage becomes greater as the distance from the ridge increases. The association of dropstones is relatively homogeneous in the region of the ridge and only at greater distances from the ridge it becomes more differentiated. Owing to their composition and distribution, as well as on the basis of characteristic fossils and rock types, the dropstones are derived from Scandinavia and Great Britain. During periods of maximum glaciation, the Iceland-Faeroe-Ridge, the Faeroe-Bank and the Bill Baileys-Bank were under ice.

Description: The aragonite compensation depth was described by pteropods in surface sediments at the northeastern Atlantic continental margin between 12° and 48° N. It rises from 3100 m up to 400 m water depth in the high-productivity zones of fertile upwelling and river discharge.

Description: Seven sediment cores from the cruises of the "Meteor" and "Valdivia" were examined palynologically. The cores were retrieved from the lower continental slope in the area of between 33.5° N and 8° N, off the West African coast. Most of the cores contain sediments from the last Glacial and Interglacial period. In some cases, the Holocene sediments are missing. Some individual cores contain sediments also from earlier Glacial and Interglacial periods. The main reason for making this palynological study was to find out the differences between the vegetation of Glacial and Interglacial periods in those parts of West Africa which at present belong to the Mediterranean zone, the Sahara and the zones of the savannas and tropical forests. In today's Mediterranean vegetation zone at core 33.5° N, forests and deciduous forests in particular, are missing during Glacial conditions. Semi-deserts are found instead of these. In the early isotope stage 1, there is a very significant development of forests which contain evergreen oaks; this is the Mediterranean type of vegetation development. The Sahara type of vegetation development is shown in four cores from between 27° N and 19° N. The differences between Glacial and Interglacial periods are very small. It must be assumed therefore that in these latitudes, both Glacial and Interglacial conditions gave rise to deserts generally. The results are in favour of a slightly more arid climate during Glacial and a more humid one during Interglacial periods. The southern boundary of the Sahara and the adjacent savannas with grassland and tropical woods were situated more to the south during the Glacial periods than they were during the Interglacial ones. In front of today's savanna belt, it can be seen from the palynological results that there are considerable differences between the vegetation of Glacial and Interglacial periods. The woods are more important in Interglacial periods. During the Glacial periods these are replaced from north to south decreasingly by grassland (savanna and rainforest type of vegetation development). The southern limit of the Sahara during stage 2 was somewhere between 12° N and 8° N which is between 1.5 and 5 degrees in latitude further south than it is today. Not only do these differences in climate and vegetation apply to the maximum of the last Glacial and for the Holocene, but they apparently apply also to the older Glacial and Interglacial periods, where they have been found in the profiles. The North African desert belt can be said to have expanded during Glacial times both towards the north and towards the south. All the available evidence of this study indicates that the grassland or the semi-deserts of Southern Europe came into connection with those of N Africa; there could not have been any forest zone between them. The present study was also a good opportunity for investigating some of the basic marine palynological problems. The very well known overrepresentation of pollen grains of the genus Pinus in marine sediments can be traced as far as 21° N. The present southern limit for the genus Pinus is on the Canaries and on the African continent at approximately 31° N. Highest values of Ephedra pollen grains even occur south of the main area of the present distribution of that genus. There does not seem to be any satisfactory explanation for this. In general, it would appear that the transport of pollen grains from the north is more important than transport from the south. The results so far, indicate strongly that further palynological studies are necessary. These should concentrate particularly on cores from between 33° N and 27° N as well as between 17° N and 10° N. It would also be useful to have a more detailed examination of sediments from the last Interglacial period (substage 5 e). Absolute pollen counts and a more general examination of surface samples would be desirable. Surface samples should be taken from the shelf down to the bottom of the continental slope in different latitudes.

Description: 33 species of polychaetes were collected, 27 of them were determined to species level. The majority of the species are cosmopolitans. Pulliella armata FAUVEL was found the first time in the Atlantic Ocean off Northwest Africa.

Description: The new Harpacticoidea genus Thieliella nov. gen. of the family Ancorabolidae SARS sensu LANG, 1909 with two new species from 500 m depth of the Island-Faroer-Ridge is described and discussed: Thieliella nordatlantica nov. spec. and Th. reducta nov. spec.

Description: 80 species of polychaetes were collected, 76 of them were determined to species level. One species (Harmothoe [Austrolaenilla] meteorae n. sp.) was described as new species. The majority of the species including the species of the cruises 26 and 44 are cosmopolitans (18%); 16% are distributed in cool temperate to tropical zones, 12.5% have their distribution in the eastern Atlantic and the Mediterranean, and 11% are distributed in tropical-subtropical to warm temperate zones.

Description: Nine species of Flustridae were collected by the R.V. "Meteor" in one subantarctic and three antarctic stations. Two new genera (Austroflustra and Neoflustra) and three new species (Austroflustra gerlachi, A. australis and Neoflustra dimorphica) are described. The diagnosis of the family is emended to include species with adventitious avicularia. Nematoflustra bifoliata D'HONDT and Flustra thysanica MOYANO are placed in the genus Securiflustra SILEN, and Flustra vulgaris KLUGE is transfered to Austroflustra.

Description: The species Stenhelia (Delavalia) noodti n. sp., Stenhelia (Delavalia) islandica n. sp., Pseudomesochra scheibeli n. sp. and Ameira faroerensis n. sp. are described from 500 m depth on the Island-Faroer-Ridge. Of special interest is Stenhelia (Delavalia) noodti n. sp. showing a reduction of the Exp A2 to one segment, a character described for this genus for the first time.

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: 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: 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.