ALBERT

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: 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: 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: 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: 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: 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: 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: 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.