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  • 1
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    Elsevier
    In:  Amsterdam, 432 pp., Elsevier, vol. 167, no. XVI:, pp. 385-389, (ISBN 1-56670-263-3)
    Publication Date: 1994
    Keywords: 93.1060 ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Textbook of geophysics ; Plate tectonics ; Fracture ; Tectonics ; Geol. aspects ; Rheology ; Stress ; cracks and fractures (.NE. fracturing) ; salt
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  • 2
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    Elsevier
    In:  Amsterdam, Elsevier, vol. 31, no. 1, pp. 1-40, (ISBN 0-691-01019-6)
    Publication Date: 1994
    Keywords: Textbook of geophysics ; Geoelectrics ; Applied geophysics
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  • 3
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    Springer
    In:  Marine Biology, 121 (2). pp. 267-272.
    Publication Date: 2020-07-14
    Description: Four research surveys of Falkland Island waters were carried out to determine the distribution and abundance of the early life-history stages of Loligo gahi (d'Orbigny, 1835) in the austral winter of 1988 and the austral springs of 1990, 1991 and 1992. Juveniles were caught during three of the four surveys in both Bongo nets and an RMT8 net. In each case, greatest numbers were consistently caught in waters of ≤100 m to the south and east of East Falkland. The use of an opening/closing net in 1992 showed that most L. gahi juveniles aggregate close to the sea floor and are more available to the sampling gear by night than by day. Limited temperature data for the 1991 and 1992 surveys suggest that distribution on the coastal shelf may be associated with water-column structure. In 1992 when temperature data implied a mixed water column, juveniles were caught in deeper water than in 1991 when the water column was stratified. The results suggest that the spawning grounds of L. gahi are probably situated to the south and east of the Falkland Islands, at least for squid hatched in the austral winter/spring.
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  • 4
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 177 (1). pp. 73-78.
    Publication Date: 2020-07-27
    Description: The periodicity of deposition of growth increments in the cuttlebone of juvenile Sepia officinalis was investigated under controlled conditions for a short period after hatching (19 days). The slope of time elapsed and increment counts was significantly different from 1 indicating that lamellae are not deposited on a daily basis. The relationship between increment counts and juvenile length was, however, highly significant. Also significant were the relationships between the number of growth increments and shell length and increment counts and cuttlebone area. These data show that the number of growth increments is related primarily to the growth rate of the juvenile rather than to its chronological age. Taking into account these data, the cuttlebone lamellae cannot be used for age determination in the juvenile cuttlefish just after hatching.
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  • 5
    Publication Date: 2018-06-15
    Description: The levels of four trace metals (Cd, Cu, Pb, and Zn) in the whole soft body and in different organs of the ocean quahog Arctica islandica were evaluated from four stations in Kiel Bay, Western Baltic. The relationships between the contents and concentrations of these metals and body size (weight and length) were also investigated. Double logarithmic plots of metal contents and concentrations against dry body weight and shell length, respectively, show straight-line relationships. The results indicate that smaller individuals have higher concentrations of Cu and Zn, two essential metals, while larger individuals have higher concentrations of Cd and Pb, two non-essential metals. The calculated regression slopes of metal content against dry-body weight revealed that Cd and Cu appear to be affected by maturation since two different slopes are observed for both metals before and after maturation. This was not obvious for Pb and Zn. Pooled slopes of metal content against dry-body weight for all animal sizes indicated that Cu and Zn have a one common slope of (0.82) and Cd and Pb another common one of (1.51). Plots of metal concentrations against shell length indicated also that Cu and Zn have one common slope of (−0.54) and Cd and Pb another one of (1.56). Moreover, it was possible to calculate one final slope of (1.53) for Cd and Pb from both content/weight and concentration/length plots. This indicates that A. islandica may have one metabolic strategy for the essential metals and another for the non-essential metals.
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  • 6
    Publication Date: 2020-06-10
    Description: A total of 40 (29 female and 11 male) Ross seals were sampled in January over three years. Seals were weighed, measured and age determined by counting dentine lines in teeth. Stomach contents were identified against reference material and species of helminths were determined using standard techniques. Asymptotes in body mass and length are reached at some nine years of age. Age class varied from 2–20 years. Antarctic silverfish Pleurogrammma antarcticum was the only fish species identified. Psychroteuthis glacialis dominated the squid component. Fish was dominant in three samples, squid was the exclusive component in two samples and a minor component in another two. Glandicephalus antarcticus, Diphyllobothrium wilsoni and Contracaecum spp were the dominant helminths present. The high proportion of empty or nearly empty stomachs conforms with the knowledge that this species moults and consequently fasts in January.
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  • 7
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    Elsevier
    In:  Aquaculture, 128 (1-2). pp. 143-152.
    Publication Date: 2017-05-11
    Description: A simple method of providing a regular supply of live food for the experimental culture of paralarval cephalopods is described. The primary food source utilized was hatched zoeae of large laboratory populations of the hermit crab, Pagurus prideaux. Zoeal size, swimming behaviour, and distribution in the water column make these zoeae a suitable live prey for rearing early post-hatching planktonic stages of cephalopods and probably other marine zooplanktivores. Ovigerous P. prideaux females were collected from the sea throughout the year at depths between 10 and 90 m in the NW Mediterranean and maintained at densities of up to 500 specimens · m−2. One month after spawning in aquaria, 38% of the females of P. prideaux started to incubate a second clutch of eggs. Other decapod crustacean species, such as Liocarcinus depurator and Dardanus arrosor, were maintained to use their zoeae as a food source for cephalopod paralarvae. P. prideaux zoeae were used as the sole or main food resource for rearing Loligo vulgaris and Octopus vulgaris, during the first 2 months of life. First feeding and initial growth in L. vulgaris and O. vulgaris paralarvae can be successfully stimulated using decapod zoeae with a total length equivalent to 50–100% of the cephalopod's mantle length.
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  • 8
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    Elsevier
    In:  Marine Pollution Bulletin, 28 (7). pp. 413-416.
    Publication Date: 2018-04-09
    Description: As long as salinity in the Baltic Sea was high (as it was between 1948 and 1982) the depth range between 70 and 100 m suffered frequent anoxia. However, when salinity was low and when the position of the halocline was deep (as it was in the first half of the century) oxygen conditions were good and long-lived macrofauna occurred. Should the present trend to lower salinities continue (building bridges across the Belt Sea and reducing salt water inflow would be helpful) one can foresee a recolonization by macrofauna in the depth range 70–100 m.
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  • 9
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 183 (1). pp. 41-52.
    Publication Date: 2019-09-23
    Description: The reproductive cycle of the sponge Halichondria panicea was investigated at Boknis Eck in the Western Kiel Bight over 2 yr, and over 1 yr on the island Helgoland in the North Sea and was compared with material collected earlier at Tjärnö at the Swedish west coast. Temperature and salinity were monitored at the different stations in order to determine whether different hydrographic conditions could be linked to differences in seasonal patterns of the reproductive cycle. The results showed H. panicea to be gonochoristic at all stations. The ratio of males to females varied between populations and years, but females predominated consistently. Comparison of the reproductive cycle in the years 1987 and 1989 at the brackish-water station Boknis Eck shows that high ambient winter and spring temperatures in 1989 resulted in a shorter period of oogenesis and earlier larval release, as compared to the year 1987. The reproductive cycle of the sponges at the fully marine station at Helgoland in 1989 and the brackish-water station at Tjärnö in 1978 under temperature and salinity conditions similar to those at Boknis Eck in 1989 showed the same seasonal pattern. We conclude that the lower salinities found at both Boknis Eck and Tjärnö do not cause a delay or slow-down of reproduction at these stations as compared to Helgoland. Under favourable temperature conditions, oogenesis was highly synchronous within the different populations, while it was more spread over time under the low ambient water temperatures at Boknis Eck in 1987.
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  • 10
    Publication Date: 2020-07-14
    Description: Geographic variation in the squid Loligo forbesi was investigated using multivariate analysis of morphometric and meristic characters in samples of squid taken from 13 localities in the Northeast Atlantic Ocean. Two character sets, body morphometrics and beak morphometrics, indicated similar patterns of variation, with squid from the Azores differing markedly from those on the continental shelf. No consistent pattern was apparent in meristic data. Partial Mantel tests indicated that similarity matrices for morphological data were significantly correlated with distance matrices for (a) geographic proximity, (b) whether the capture site was on the continental shelf or the Azorean bank, and (c) (beak data only) average seasurface temperature at site of capture. Partial Mantel tests on allozyme data for the same individuals support hypothesis (b). The results suggest that L. forbesi in the Azores may reasonably be regarded as a distinct stock, differing significantly from L. forbesi on the continental shelf.
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  • 11
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    Springer
    In:  Marine Biology, 119 (3). pp. 413-421.
    Publication Date: 2020-07-14
    Description: Abralia trigonura is a small squid that is an important member of the mesopelagic boundary community around Hawaii. Squids were aged by examining statolith growth increments, and various reproductive parameters were measured. Female longevity is ∼6 mo, and they become sexually mature at ∼3.5 mo. Male longevity is the same, but they become sexually mature at ∼2.5 mo. This species appears to be a multiple spawner, and peculiarities in the number of eggs found in the oviducts suggests that they spawn every few days. Possible advantages of this reproductive mode are examined.
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  • 12
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    Springer
    In:  Marine Biology, 120 (2). pp. 171-180.
    Publication Date: 2017-08-03
    Description: The home range system of the coelacanth Latimeria chalumnae was investigated along 11 km coastline at Grande Comore, Western Indian Ocean, between 1987 and 1991. 67 individuals were identified on individual white dot patterns. The home range consisted of daytime caves where fish aggregated in groups of up to 14 individuals while at night individuals moved singly downwards to a depth of 250 to 300 m in search of food. Site fidelity of at least 5 yr was found. The coelacanths used several caves within their home ranges. Cave size, cave occupation rate, average and maximum group size and cave preferences were studied. Tracking experiments with ultrasonic transmitters revealed horizontal home ranges of at least 8 km width. Population estimates of 200 to 230 individuals at Grande Comore confirm earlier counts. Large home ranges and highly mobility in a topographically narrow habitat apparently favoured inbreeding of the small local island population.
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  • 13
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    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 41 (2). pp. 263-281.
    Publication Date: 2018-06-19
    Description: In the Deep Western Boundary Current (DWBC) mean velocities obtained by the F11/F12 dating method are far smaller (1–2 cm s−1) than direct velocity measurements (5–20 cm s−1). To resolve this discrepancy, a simple box model is presented that uses the ideas of Pickartet al. (1989, Physical Oceanography, 19, 940–951) to parametrize turbulent diffusion of the current with its surroundings. In contrast to previous models, however, the boundary conditions include all water masses forming the lower part of the DWBC (Denmark Strait Overflow Water, Iceland Scotland Overflow Water and Northeast Atlantic Water). The model-derived mean velocity of the DWBC leads to tracer concentrations that have to fit the observed F11 and F12 distributions, the F11/F12 ratios, and the tritium distributions. Moreover, the model area is extended from south of the Faroe bank along the continental margin of the American continent to 10°S. The model assumes uniform velocity and uniform turbulent mixing along the flow path of the DWBC, and enhanced turbulent mixing in the vicinity of the current compared to the ocean's interior allows the surrounding waters, which remain motionless, to accumulate tracers. The highest mean velocity of the DWBC, which results in model F12, F11, and 3H distributions as well as F11/F12 ratios, compatible to measurements of these tracers along the western boundary, are 4.8 cm s−1. Variations in the composition of the DWBC as well as changes in the time history of the source water masses do not increase the range of the model velocities.
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  • 14
    Publication Date: 2019-09-23
    Description: Eleven fish species from the Weddell Sea (Antarctic) were examined for infestation with anisakid nematodes. Two species of the genus Contracaecum and the sealworm Pseudoterranova decipiens were isolated from the liver and the body cavity of fish affected. Only two specimens of P. decipiens (1.4%) partly invaded the belly flaps. The following fish species were infested by P. decipiens at the given prevalences: Cygnodraco mawsoni (74.4%), Trematomus scotti (23.2%), Pagetopsis maculatus (10.0%), Cryodraco antarcticus (7.1%), Trematomus lepidorhinus (3.0%), and Dolloidraco longedorsalis (2.7%). All of these, except Trematomus scotti, are new host records. Chaenodraco wilsoni, Chionodraco myersi, Gerlachea australis, Racovitzia glacialis and T. eulepidotus were not infested. The reasons for low prevalence and intensity of infestation are seen in the difficulties of P. decipiens in completing its benthic life cycle in the Weddell Sea environment, in the absence of shallow coastal waters due to the floating shelf-ice. Cygnodraco mawsoni is a crucial intermediate host, without which completion of the parasite life cycle might not be possible. In order to clarify the taxonomical position of Antarctic Pseudoterranova, morphological comparisons with specimens of P. decipiens from the German and Norwegian coast were made using scanning electron microscopy. Results revealed no differences; hence, all specimens studied belong to the same species P. decipiens.
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  • 15
    Publication Date: 2017-08-23
    Description: Planktic foraminifers Neogloboquadrina pachyderma (sin.) from 87 eastern and central Arctic Ocean surface sediment samples were analyzed for stable oxygen and carbon isotope composition. Additional results from 52 stations were taken from the literature. The lateral distribution of δ18O (Full-size image (〈1 K)) values in the Arctic Ocean reveals a pattern of roughly parallel, W-E stretching zones in the Eurasian Basin, each ∼0.5‰ wide on the δ18O scale. The low horizontal and vertical temperature variability in the Arctic halocline waters (0–100 m) suggests only little influence of temperature on the oxygen isotope distribution of N. pachyderma (sin.). The zone of maximum δ18O values of up to 3.8‰ is situated in the southern Nansen Basin and relates to the tongue of saline (〉 33%.) Atlantic waters entering the Arctic Ocean through the Fram Strait. δ18O values decrease both to the Barents Shelf and to the North Pole, in accordance with the decreasing salinities of the halocline waters. In the Nansen Basin, a strong N-S δ18O gradient is in contrast with a relatively low salinity change and suggests contributions from different freshwater sources, i.e. salinity reduction from sea ice meltwater in the south and from light isotope waters (meteoric precipitation and river-runoff) in the northern part of the basin. North of the Gakkel Ridge, δ18O and salinity gradients are in good accordance and suggest less influence of sea ice melting processes. The δ13C (Full-size image (〈1 K)) values of N. pachyderma (sin.) from Arctic Ocean surface sediment samples are generally high (0.75–0.95‰). Lower values in the southern Eurasian Basin appear to be related to the intrusion of Atlantic waters. The high δ13C values are evidence for well ventilated surface waters. Because the perennial Arctic sea ice cover largely prevents atmosphere-ocean gas exchange, ventilation on the seasonally open shelves must be of major importance. Lack of δ13C gradients along the main routes of the ice drift from the Siberian shelves to the Fram Strait suggests that primary production (i.e. CO2 consumption) does probably not change the CO2 budget of the Arctic Ocean significantly.
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  • 16
    Publication Date: 2016-04-08
    Description: Two major meltwater events are documented in cores from the NW Labrador Sea. One occurred ca. 20,000 14C yr B.P. in association with deposition of a major detrital carbonate unit. Both prior to and after this event, δ18O values of near-surface planktonic foraminifera were 4.5%, indicating fully enriched glacial values. A younger event (ca. 14,000 14 C yr B.P.) is characterized by a dramatic change in δ18O from 4.5 to 2.0% and coincided with the retreat of ice from the outer SE Baffin Shelf, possibly into Hudson Strait. These meltwater events coincide with Heinrich (H) layers 1 and 2 from North Atlantic sediments. The 14,000 14C yr B.P. meltwater event indicates that the eastern margin of the Laurentide Ice Sheet also underwent rapid retreat at approximately the same time as other ice sheet margins around the NE North Atlantic. A third major detrital carbonate event at the base of HU87-033-009, possibly correlative with Heinrich layer 3, occurred ca. 33,960 ± 675 14 C yr B.P.; however, this is older than the accepted date for H-3 of 27,000 14C yr B.P. and may be H-4.
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  • 17
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    Springer
    In:  In: Carbon cycling in the glacial ocean: Constraints in the ocean's role in global change. , ed. by Zahn, R., Pederson, T. F., Kannish, M. A. and Labeyrie, L. NATO ASI Series, 1 (17). Springer, Berlin, Germany, pp. 87-104. ISBN ISBN 0-387-57594-4
    Publication Date: 2020-04-14
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  • 18
    Publication Date: 2019-09-24
    Description: For over thirty years man has studied “outer space” and installed satellites which watch the surface of the Earth. The great depths of the world ocean are, however, practically unknown and there is an urgent need to put abyssal benthic laboratories into “inner space” in order to study basic phenomena of interest to marine science and climatology as well as man's impact on the oceans. In view of the numerous problems related to global change, as a first step emphasis should first be on the role of the oceans and their inherent processes, which are the focus of such international programmes as the World Ocean Circulation Experiment (WOCE) and the Joint Global Ocean Flux Study (JGOFS). Multi-disciplinary registration of key events at selected key sites investigating the variability in time and space are of the utmost importance. The same methods and techniques must be used for the study of human impacts on the deep oceans caused by mining of metalliferous resources and by waste disposal as well as in basic studies. However, the investigation of the inner space of our planet has certain requirements. As long-term and large-scale investigations become more and more important, development of automized systems, largely independent from research vessels will be required. This will demand high capacities of energy for all technical functions as well as high storage capacities for data and samples. As a consequence the needs for two different—although overlapping—functional approaches are defined for future deep-sea deployments. (A) A system for long-term registration of the natural variability and long-term monitoring of human impacts: (B) A system for short-term observations and short-time experimentations. This report summarizes their technological demands. The envisioned interdisciplinary technology should deliver information on physical, biological and geochemical processes and their variabilities in the deep oceans. The prospected systems need to have the ability for real time video observation, data transfer and experimental manipulation, as well as sensing and sampling facilities with large storage capacities for long-term deployments. Prospective costs of the described multipurpose abyssal benthic laboratory will presumably exceed the funds for deep-sea research of a single country. A joint European effort could solve this problem and help to manifest a leading role for European marine science in international deep-sea and global change research.
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  • 19
    Publication Date: 2017-09-26
    Description: Three groups of REE patterns are observed for the sandstones and shales of the Middle Ordovician Austin Glen Member of the Normanskill Formation. One sandstone sample is enriched in middle and light rare earth elements. The majority of samples are light rare earth element (LREE) enriched with negative Eu-anomalies and flat heavy rare earth elements (HREEs), whereas a third group appears to have lost LREEs and middle rare earth element (MREEs). Homogeneous neodymium isotopic compositions for all samples at about the time of deposition, ϵNd (470 Ma) = −8.2 ± 1.1(2SD), indicate that the source of the Austin Glen Member was well mixed and that the neodymium had a long-term enriched history. The differences in the shape and abundances of the REE patterns combined with the neodymium isotope characteristics of the samples lead us to the conclusion that samarium and neodymium were fractionated and that the neodymium isotopic system might have been disturbed at about the time of deposition (470 Ma). Most samples appear to have been affected by this process. The two most altered shales lost about half of their neodymium and their ratios are higher than the ratios of average shales. These two shales give clearly erroneous mantle-extraction ages, but the average TDM of the provenance can still be deduced (1700–1800 Ma) from the least disturbed sandstones with normal upper crustal ratios. Accordingly, this study demonstrates that the REEs may be transported and neodymium isotopes may be reequilibrated under certain sedimentary conditions (e.g., diagenesis). However, in spite of evidence for REE redistribution, provenance information (TDM, original REE patterns) may still be inferred.
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  • 20
    Publication Date: 2019-09-23
    Description: The winter ice-regime of the 〈80 km wide Alaskan Beaufort Sea shelf is characterized by compression and shearing, resulting in the formation of major grounded pressure ridge systems stabilizing the fast ice on the mid-shelf, and essentially no open-water areas. In contrast, the winter ice-regime of the 500-km wide Laptev Sea shelf is controlled by winds blowing from land to sea, and is therefore dilational. A perennial polynya borders the hundreds of kilometers-wide and very smooth fast ice offshore. In this body of open water, rapidly forming ice is continuously advected offshore by the mean wind field, making the Laptev Sea the single major ice factory for the Arctic Ocean and Transpolar Drift. Conversely, with summer warming this dark polynya turns into an area of high heat gain, which results in the retreat of the ice edge to a much higher latitude and greater distance (〉500 km) from the mainland than in the Beaufort Sea. As a result, the annual freeze-up does not incorporate old, deep-draft ice, and with a lack of compression, such deep-draft ice is not generated in situ, as on the Beaufort Sea shelf. The Laptev Sea has as much as 1000 km of fetch at the end of summer, when freezing storms move in and large (6 m) waves can form. Also, for the first three winter months, the polynya lies inshore at a water depth of only 10 m. Turbulence and freezing are excellent conditions for sediment entrainment by frazil and anchor ice, when compared to conditions in the short-fetched Beaufort Sea. We expect entrainment to occur yearly. Different from the intensely ice-gouged Beaufort Sea shelf, hydraulic bedforms probably dominate in the Laptev Sea. Corresponding with the large volume of ice produced, more dense water is generated in the Laptev Sea, possibly accompanied by downslope sediment transport. Thermohaline convection at the midshelf polynya, together with the reduced rate of bottom disruption by ice keels, may enhance benthic productivity and permit establishment of open-shelf benthic communities which in the Beaufort Sea can thrive only in the protection of barrier islands. Indirect evidence for high benthic productivity is found in the presence of walrus, who also require year-round open water. By contrast, lack of a suitable environment restricts walrus from the Beaufort Sea, although over 700 km farther to the south. We could speculate on other consequences of the different ice regimes in the Beaufort and Laptev Seas, but these few examples serve to point out the dangers of exptrapolating from knowledge gained in the North American Arctic to other shallow Arctic shelf settings.
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  • 21
    Publication Date: 2018-01-17
    Description: Biometric analyses on shells of Turborotalita quinqueloba (Natland) reflect the paleoceanographic conditions in the Norwegian-Greenland Sea (NGS). Both median and mean size variations exhibit a steady increase after the Last Glacial Maximum (LGM). After Termination I the size eventually reaches a constant level with only minor fluctuation. In contrast, peak abundances of specimens occur somewhat later, during the Holocene climatic optimum and rapidly decrease again in the youngest sediments. Test sizes are larger at the Vøring Plateau in the vicinity of incoming Atlantic water than in water further to the west. Turborotalita quinqueloba first appeared in the southwestern part of the NGS with a preliminary major peak in abundance and size well below the Younger Dryas. This species was present in sizes 〈 125 μm in this area during almost entire oxygen isotopic Stage 2. This was not observed in the more easterly located cores. It seems likely that size variations as a ‘tool’ for NGS paleoceanographic interpretations are not only valuable for the time since the LGM, but can also be applied to older isotopic stages where abundances of T. quinqueloba are low or absent in the 〉 125 μm size-fractions but are high in the 63–125 μm fraction (e.g. Stages 7, 9 and 11).
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  • 22
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    Elsevier
    In:  Review of Palaeobotany and Palynology, 80 (3-4). pp. 209-234.
    Publication Date: 2016-09-14
    Description: Among living green algae assigned to the order Chlorococcales and order Zygnematales certain species develop resistant outer organic walls and/or cysts during their life cycles: as such they have the potential to become fossils. Based on morphology,comparison between living algae and microfossil remains are made with varying degrees of confidence, and a possible evolutionary pathway for certain chlorococcalean coenobial families is suggested. Twelve genera are reviewed from earliest to latest Triassic palynological assemblages from northwestern Australia; and the following taxa are described as new: Plaesiodictyon mosellanum ssp. symmetricum ssp. nov.; Plaesiodictyon mosellanurn ssp. variabile ssp. nov.; Plaesiodictvon decussatus sp. nov.: Plaesiodico'on decussatus ssp. decussatus ssp. nov.; Plaesiodictyon decussatus ssp. tetracornuta ssp. nov.; Tetraporina protrusa sp. nov.: Crucigeniella? torques sp. nov.; and Paleoraphidia akestra gen. et sp. nov. (type). Their suggested natural affinities are useful in palaeoenvironmental interpretations of mostly freshwater or low-salinity habitats.
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  • 23
    Publication Date: 2017-05-30
    Description: A method is presented to determine the extent of iron complexation by natural organic ligands in seawater. Catalytic cathodic stripping voltammetry (CSV) is used to take advantage of ligand competition between the added ligand, 1-nitroso-2-napthol (NN), and natural ligands present in seawater. The conditional stability constant for the complexation of iron by NN was calibrated for salinities between 1 and 36 using ligand competition with EDTA. The values of log K'(Fe(NN))3 (valid for pH 6.9 seawater) were found to vary linearly with log salinity according to log K'(Fe(NN))3 = - 1.04 +/- 0.08 log(salinity) + 30.12 +/- 0.09. The detection window, defined by the iron complexing ability of NN was altered by varying the concentration of NN. Preliminary measurements of iron complexing ligands in samples from coastal and open oceanic origin revealed the presence of natural complexing ligands at concentrations higher than that of total dissolved iron. The stability constants for the complexes were high, log K'(FeL) falling within the range of 18.8-21.2, indicating that by far the greatest component (99%) of the dissolved iron occurs organically complexed in pH 6.9 seawater. Model calculations showed that it is possible that the organic fraction may be somewhat less at a pH value near 8.
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  • 24
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    Springer
    In:  In: Understanding the North Sea System. Springer, Heidelberg, Germany, pp. 97-113. ISBN 978-94-010-4540-7
    Publication Date: 2015-10-07
    Description: Coupling of physical, biological and chemical processes associated with particle resuspension and seston flux was investigated at three sites in the North Sea with contrasting water column (mixed/stratified) and seabed (cohesive/non-cohesive) characteristics.
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  • 25
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    Elsevier
    In:  Earth and Planetary Science Letters, 125 (1-4). pp. 105-118.
    Publication Date: 2016-11-14
    Description: To investigate the growth rates and absolute time stratigraphy of marine hydrogenetic ferromanganese encrustations, we performed 10Be profiling and ‘Co chronometry’ of crustal layers, as well as 87Sr86Sr and δ18O analysis of phosphatised limestone (francolite) within a ∼ 9.5 cm thick ferromanganese crust from Schumann Seamount in the Hawaiian Archipelago. Together with microfossil stratigraphy, our results indicate that some seamount crusts greatly exceed the commonly accepted Miocene maximum age, in this case probably approaching the Cretaceous age of the seamount. In addition to the unconformity at the crust-substrate boundary, at least eight major disconformities are indicated in the Schumann Seamount crust which probably represent depositional hiatuses or episodes of crust erosion. Three of the six upper disconformities can be placed at the Plio-Pleistocene, Middle Miocene and Paleocene-Eocene based on 10Be, microfossil and Co chronometer evidence. 87Sr86Sr and δ18O values of purified francolite from an inclusion-rich layer between the depths of 44 and 49 mm suggest apparent ages that approach those of Eocene-Late Paleocene microfossils reported in overlying layers, whereas francolite vein infillings in the lower part of the crust and in the basaltic substrate yield values that, if interpreted as ages of phosphatization, suggest a minimum Oligocene age. Paleotracking suggests the phosphogenesis observed here and on other Central Pacific seamounts could not have resulted from upwelling enhanced productivity associated with equatorial divergence if the Oligocene and Middle Miocene isotopic ages reported here and elsewhere are correct; however, a maximum Late Paleocene age for the phosphogenesis, consistent with the stratigraphy, would place these seamounts within 10°N of the equator. Paleotracking also suggests northeast tradewind transport of aluminosilicates in the Cenozoic, in agreement with other evidence for the antiquity of this ferromanganese crust.
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  • 26
    Publication Date: 2017-12-06
    Description: We present comprehensive geochemical analyses on samples from the active volcanoes of the Society and Austral hotspot chains, including data for major, trace and rare-earth elements, and Sr, Nd, Pb and Th isotopes. The latter can be used to determine the Th/U in the source at the time of melting, and so give a constraint on the absolute amount of incompatible-element fractionation occurring during melting. SiO2 vs. MgO variations show evidence for variable amounts of a nephelinitic melt component (low SiO2, low MgO) in all the magmas studied. The nephelinite is probably produced in the presence of CO2 during melting. Correlations between SiO2 and the degree of ThU fractionation (derived from Th isotope measurements) imply that the CO2-driven, nephelinitic melting is also responsible for fractionating the Th/U ratio. Comparing the Th isotopes with Sr, Nd and Pb isotopes, it is possible to place limits on the Th/U ratios in the EM II (Societies) and HIMU (Australs) sources. These are ∼ 3.4 and ⩽ 2.5, respectively. The Nb/U ratio, which was previously thought to be relatively constant in all oceanic volcanics (47 ± 10), is shown to be anomalously low (25 ± 5) in some of the Society Seamounts and high (60) in some of the Australs. This confirms the presence of continent-derived material in the Society source and suggests that HIMU volcanics may have elevated Nb/U ratios. The change in Pb isotope compositions in the Australs, from HIMU (e.g., Tubuai) before 6 Ma to the more recent, less extreme compositions seen for example at Macdonald, is the result of a small amount of subducted sediment contaminating the pure old recycled oceanic crust component which, before 6 Ma, yielded HIMU.
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  • 27
    Publication Date: 2016-09-20
    Description: About 73% of the water exchange between the Baltic and the North Seas is via the Darss Sill. Joint Danish and German marine geological investigations, including shallow seismic surveys and sediment sampling, have been carried out in the Darss Sill area between 1989 and 1991. Results from these studies and unpublished archive data from the Institute of Baltic Sea Research, Warnemünde, are presented. These show that the entire Quaternary sedimentary sequence in most of the area is at least 40 m thick. A zone of glacial till outcropping between Denmark and Germany belongs to the Late Weichselian ice marginal line G (“Velgaster Staffel”). The formation of this line caused the damming of a pre-existing (sub)glacial meltwater discharge system. At the beginning of the Baltic Ice Lake formation, a deep and presently buried channel incised in this ice marginal line was part of a (glacio)fluvial drainage system with discharge towards the northeast, i.e. into the Baltic Ice Lake. During the Baltic Ice Lake transgression damming of the Darss Sill occurred due to accumulation of sandy sediments within this channel. On the other hand, the recent Kadet Channel was only occasionally overflown during the Baltic Ice Lake highstand maximum, which was 18 m BSL (below present sea level) in the Darss Sill area. The main erosion and deepening of the Kadet Channel began during the Ancylus Lake highstand maximum. At present, sediment transport on the Darss Sill is governed by northeasterly inflow of saline bottom waters in the entire area from the Kadet Channel to the German coast. Baltic outflow affects the seabed at shallower depth in the Danish sector. Large-scale current-induced bedforms in the area include, amongst others, sandwaves with a height of 5 m. Changes of the bedforms observed indicate a maximum bottom flow speed of 70–100 cm s−1, both for inflow and for outflow.
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  • 28
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    Elsevier
    In:  Deep-Sea Research Part II-Topical Studies in Oceanography, 41 . pp. 307-324.
    Publication Date: 2016-10-10
    Description: Measurements of the chlorofluorocarbons (CFCs), F11 (CCl3F) and F12 (CCl2F2) were made during the Shelf Edge Exchange Processes II (SEEP-II) experiment in the Middle Atlantic Bight during 1988–1989. These compounds undergo large seasonal variations in surface water concentration as a result of temperature-induced solubility changes. Outgassing in summer produces vertical concentration gradients that can be exploited to estimate a cross-pycnocline vertical eddy-diffusivity suitable for biogeochemical flux calculations. Model results based on an exploratory study suggest an average Kz of 1 × 10−5 m2 s−1 for this region during the stratified period. CFCs have advantages over other budget approaches for studying mixing processes, including heat budgets, as there are no internal sources or sinks other than air-sea gas exchange. In order to exploit further the CFC budget of sub-pycnocline shelf waters, regular cruises through the summer months and characterization of CFC levels at the time of stratification are required.
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  • 29
    Publication Date: 2018-06-06
    Description: RNA/DNA ratios in individual herring (Clupea harengus) larvae (collected from Kiel Bay, Baltic Sea, in 1989) were measured and proved suitable for determining nutritional status. Significant differences between fed and starving larvae appeared after 3 to 4 d of food deprivation in larvae older than 10 d after hatching. The RNA/DNA ratio showed an increase with age or length of the larvae and was less pronounced in starving larvae compared to fed larvae. The individual variability of RNA/DNA ratios in relation to larval length of fed larvae and of larvae deprived of food for intervals of 6 to 9 d is presented. Based on the length dependency and the individual variability found within the RNA/DNA ratios, a laboratory calibration is given to determine whether a larva caught in the field has been starving or not. An example for a field application is shown.
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  • 30
    Publication Date: 2016-10-10
    Description: The Shelf Edge Exchange Processes II (SEEP-II) program was designed to examine the potential for export of organic carbon from the continental shelf to the deeper ocean. In the Middle Atlantic Bight of the east coast, U.S.A., a “cold pool” of relict winter water is isolated by the development of a strong seasonal thermocline on the shelf. Oxygen concentrations were monitored in and above the cold pool from March 1988 to May 1989, with electrodes moored at 19 and 38 m at a 42-m station off the Delmarva Peninsula, eastern U.S.A. An oxygen-flux simulation model was constructed to describe long-term changes in oxygen concentration and saturation. The model utilized biological rate and biomass measurements obtained at the mooring location during cruises. Vertical eddy diffusion was constrained by comparison with the redistribution of chlorofluorocarbons and heat after stratification, and by sensitivity analyses. Model predictions of the average daily change in oxygen concentration and saturation at 38 m were in good agreement with average changes recorded by moored oxygen sensors, when biological generation of oxygen was approximately equal to the thermotrophic consumption. Strong, but transient, fluctuations concentration and saturation were clearly associated with specific advective events, and had little lasting impact on the overall long-term trends. Consequently, model parameters derived from intermittent, cruise-based observations yielded satisfactory predictions of long-term trends. A carbon budget was constructed for the stratified summer period from data that largely overlapped with those used for the oxygen model. The continental shelf ecosystem operates in approximate balance during the summer, with a potential export of no more than 4% of primary production.
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  • 31
    Publication Date: 2019-09-23
    Description: Despite the Arctic sea ice cover's recognized sensitivity to environmental change, the role of sediment inclusions in lowering ice albedo and affecting ice ablation is poorly understood. Sea ice sediment inclusions were studied in the central Arctic Ocean during the Arctic 91 expedition and in the Laptev Sea (East Siberian Arctic Region Expedition 1992). Results from these investigations are here combined with previous studies performed in major areas of ice ablation and the southern central Arctic Ocean. This study documents the regional distribution and composition of particle-laden ice, investigates and evaluates processes by which sediment is incorporated into the ice cover, and identifies transport paths and probable depositional centers for the released sediment. In April 1992, sea ice in the Laptev Sea was relatively clean. The sediment occasionally observed was distributed diffusely over the entire ice column, forming turbid ice. Observations indicate that frazil and anchor ice formation occurring in a large coastal polynya provide a main mechanism for sediment entrainment. In the central Arctic Ocean sediments are concentrated in layers within or at the surface of ice floes due to melting and refreezing processes. The surface sediment accumulation in central Arctic multi-year sea ice exceeds by far the amounts observed in first-year ice from the Laptev Sea in April 1992. Sea ice sediments are generally fine grained, although coarse sediments and stones up to 5 cm in diameter are observed. Component analysis indicates that quartz and clay minerals are the main terrigenous sediment particles. The biogenous components, namely shells of pelecypods and benthic foraminiferal tests, point to a shallow, benthic, marine source area. Apparently, sediment inclusions were resuspended from shelf areas before and incorporated into the sea ice by suspension freezing. Clay mineralogy of ice-rafted sediments provides information on potential source areas. A smectite maximum in sea ice sediment samples repeatedly occurred between 81°N and 83°N along the Arctic 91 transect, indicating a rather stable and narrow smectite rich ice drift stream of the Transpolar Drift. The smectite concentrations are comparable to those found in both Laptev Sea shelf sediments and anchor ice sediments, pointing to this sea as a potential source area for sea ice sediments. In the central Arctic Ocean sea ice clay mineralogy is significantly different from deep-sea clay mineral distribution patterns. The contribution of sea ice sediments to the deep sea is apparently diluted by sedimentary material provided by other transport mechanisms.
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  • 32
    Publication Date: 2016-09-08
    Description: A hierarchy of ENSO (El Niño/Southern Oscillation) prediction schemes has been developed which includes statistical schemes and physical models. The statistical models are, in general, based on advanced statistical techniques and can be classified into models which use either low-frequency variations in the atmosphere (sea level pressure or surface wind) or upper ocean heat content as predictors. The physical models consist of coupled ocean-atmosphere models of varying degrees of complexity, ranging from simplified coupled models of the lsquoshallow waterrsquo-type to coupled general circulation models. All models, statistical and physical, perform considerably better than the persistence forecast on predicting typical indices of ENSO on lead times of 6 to 12 months. The most successful prediction schemes, the fully physical coupled ocean-atmosphere models, show significant prediction abilities at lead times exceeding one year period. We therefore conclude that ENSO is predictable at least one year in advance. However, all of this applies to gross indices of ENSO such as the Southern Oscillation Index. Despite the demonstrated predictability, little is known about the predictability of specific features known to be associated with ENSO (e.g. Indian Monsoon rainfall, Southern African drought, or even off-equatorial sea surface temperature). Nor has the relative importance for prediction of different regional anomalies or different physical processes yet been established. A seasonal dependence in predictability is well established, but the processes responsible for it are not fully understood.
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  • 33
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    Elsevier
    In:  Journal of Marine Systems, 5 (6). pp. 411-423.
    Publication Date: 2017-06-26
    Description: Vertical flux of particulate material was recorded with moored sediment traps during 1988/1989 in the Greenland Sea at 72 degrees N, 10 degrees W. This region exhibits pronounced seasonal variability in ice cover. Annual fluxes at 500 m water depth were 22.79, 8.55, 2.39, 3.81 and 0.51 g m(-2) for total flux (dry weight), carbonate, particulate biogenic silicate, particulate organic carbon and nitrogen, respectively. Fluxes increased in April, maximum rates of all compounds occurred in May-June, and consistently high total flux rates of around 100 mg m(-2)d(-1) prevailed during the summer. The increasing flux of biogenic particles measured in April is indicative of an early onset of algal growth in spring. Small pennate diatoms dominated in the trap collections during April, and were still numerous during the high flux period when Thalassiosira species were the most abundant diatoms. During May-June, up to 22% of the Thalassiosira cells collected were viable-looking cells. The faecal pellet flux increased after the May-June event. Therefore we conclude that the diatoms settled as phytodetritus, most likely in rapidly sinking aggregates. From seasonal nutrient profiles it is concluded that diatoms contribute 25% to new production during spring and 50% on an annual basis. More than 50% of newly produced silicate particles are dissolved above the 500 m horizon. High new production during spring does not lead to a pronounced sedimentation pulse of organic matter during spring but elavated vertical export is observed during the entire growth period
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  • 34
    Publication Date: 2018-01-24
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  • 35
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    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 41 (7). pp. 1053-1068.
    Publication Date: 2018-01-17
    Description: The mean residence time of river-runoff on the shelves and in the halocline of the Arctic Ocean is estimated from salinity and tracer data (tritium, 3He and the 18O/16O ratio). These estimates are derived from comparison of apparent tracer ages of the halocline waters using a combination of tracers that yield different information: (1) the tritium “vintage” age, which records the time that has passed since the river-runoff entered the shelf; and (2) the tritium/3He age, which reflects the time since the shelf waters left the shelf. The difference between the ages determined by these two methods is about 3–6 years. Correction for the initial tritium/3He age of the shelf waters (about 0.5–1.5 years) yields a mean residence time of the river-runoff on the shelves of the Siberian Seas of about 3.5 ± 2 years.
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  • 36
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    Elsevier
    In:  Marine Geology, 121 (1-2). pp. 121-128.
    Publication Date: 2016-06-23
    Description: Two cores recovered in the Greenland Sea contain aggregates (up to 5 cm in diameter) of poorly sorted coarse-grained material. Their lithologic and biogenic content, in addition to the grain size and grain shape, indicate that they are related to till balls. It is possible that they formed in a fluvial or nearshore environment (perhaps in Greenland or Siberia), were frozen into fast ice, and were then transported by sea ice-rafting to their present location. Since the balls were still partly frozen, they could survive the 2000 m drop through the water column to the seafloor.
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  • 37
    Publication Date: 2016-06-22
    Description: The Cenozoic margins of the Norwegian-Greenland Sea offer ideal conditions for passive margin studies. A series of structural elements, first observed on these margins, led to the concept of volcanic passive margins. Questions still remain about the development of such features and the location of the boundary between oceanic and continental crust. Despite the thin sediment cover of the margins, seismic reflection data are not able to image the deeper structures due to the occurrence of igneous rocks at shallow depth. This paper presents a 320-km long profile perpendicular to the strike of the main structural units of the Lofoten Margin in Northern Norway. A geological model is proposed, based on observations made with ocean bottom seismographs, which recorded seismic refraction data and wide angle reflections, along with a seismic reflection profile covering the same area. Ray-tracing was used to calculate a geophysical model from the shelf area into the Lofoten basin. The structures typical of a volcanic passive margin were found, showing that the Lofoten Margin was influenced by increased volcanic activity during its evolution. The ocean/continent transition is located in a 30-km wide zone landwards of the Vøring Plateau escarpment. The whole margin is underlain by a possibly underplated, high velocity layer. Evidence for a pre-rift sediment basin landwards of the escarpment, overlain by basalt flows, was seen. These structural features, related to extensive volcanism on the Lofoten Margin, are not as distinct as further south along the Norwegian Margin. Viewed in the light of the hot-spot theory of White and McKenzie (1989) the Lofoten Margin can be interpreted as a transitional type between volcanic and non-volcanic passive margin.
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  • 38
    Publication Date: 2019-05-14
    Description: A combined high resolution seismic, sub-bottom profiling, and multi-beam echo-sounding survey in the Skagerrak (Danish sector of the North Sea) together with gas analyses at a station along the profile exhibit the expulsion of gas (mainly methane) and the presence of gas-charged sediments at shallow depth. The echo-soundings yield detailed insight into the distribution and shape of typical sea-floor features associated with gas seepage, such as pockmarks. The pockmarks reach dimensions of 800 m in length, 300 m in width, and 15 m in depth, with the long axis running parallel to the slope of the Norwegian Trench. Processing of the multi-channel high resolution seismic data and the digitally recorded sub-bottom profiler signals indicate an internal compressional velocity of about 1050 m s-1 within the gas-charged sediments reaching from the sea-floor to a sub-bottom depth of about 23 m. Using the lateral distribution and thickness of the gas-charged sediments in conjunction with a mean concentration of gas of 3000 ppb, the present amount of trapped gas is estimated to be 6·45 × 1011 g CH4. The flux of methane through the sea-bed into the water column appears to be 7·2 × 1010 g CH4 per year. To explain the small difference in size between the methane pool in near-surface sediments and the annual flux through the sea-bed, a constantly high supply of methane from leaking hydrocarbon reservoirs at greater depths has to be active.
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  • 39
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    In:  Climate Dynamics, 10 (6-7). pp. 267-276.
    Publication Date: 2016-09-08
    Description: Based on a combined data set of sea surface temperature, zonal surface wind stress and upper ocean heat content the dynamics of the El Niño phenomenon is investigated. In a reduced phase space spanned by the first four EOFs two different stochastic models are estimated from the data. A nonlinear model represented by a simulated neural network is compared with a linear model obtained with the principal oscillation pattern (POP) analysis. While the linear model is limited to damped oscillations onto a fix point attractor, the nonlinear model recovers a limit cycle attractor. This indicates that the real system is located above the bifurcation point in parameter space supporting self-sustained oscillations. The results are discussed with respect to consistency with current theory.
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  • 40
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    Elsevier
    In:  Analytica Chimica Acta, 284 (3). pp. 463-471.
    Publication Date: 2020-06-03
    Description: An automated and semi-intelligent voltammetric system is described for trace metal analysis. The system consists of a voltammeter interfaced with a personal computer, a sample changer, 2 peristaltic pumps, a motor burette and a hanging mercury drop electrode. The system carries out fully automatically approximately 5 metal determinations per hour (including at least 3 repetitive scans and calibration by standard addition) at trace levels encountered in clean sea water. The computer program decides what level of standard addition to use and evaluates the data prior to switching to the next sample. Alternatively, the system can be used to carry out complexing ligand titrations with copper whilst recording the labile copper concentration; in this mode up to 8 full titrations are carried out per day. Depth profiles for chromium speciation in the Mediterranean Sea and a profile for copper complexing ligand concentrations in the North Atlantic Ocean measured on board-ship with the system are presented. The chromium speciation was determined using a new method to differentiate between Cr(III) and Cr(VI) utilizing adsorption of Cr(III) on silica particles.
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  • 41
    Publication Date: 2020-06-03
    Description: The use of in-line UV-digestion for breakdown of dissolved organic matter (DOM), prior to voltammetric determination of trace metals in natural samples, is discussed in this paper. Destruction of DOM is necessary to free trace metals that are organically complexed and to remove interfering organic surfactants. Complete breakdown of DOM in natural water samples is achieved by in-line UV-digestion using a 100 W medium pressure mercury vapour lamp and a silica coil, at a sample digestion time of 4.5 min. The efficiency of the system is tested with destruction of humic acid, conversion of Cr(III) to Cr(VI), and the release of Ni and Cu from organic complexes in sea water. The in-line application of UV is illustrated by automated voltammetry of nanomolar levels of Cu and Ni in samples from oceanic origin.
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  • 42
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    Elsevier
    In:  TrAC - Trends in Analytical Chemistry, 13 (9). pp. 348-352.
    Publication Date: 2020-05-04
    Description: Instrumentation and methods are described for collecting surface sea water using pumping with subsequent in-line analysis by stripping voltammetry or chronopotentiometry. The review is illustrated with data for estuarine copper and nickel, and the distribution of nickel in Liverpool Bay.
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  • 43
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    In:  Polar Biology, 14 (3). pp. 205-210.
    Publication Date: 2020-10-05
    Description: Energy requirements of resting Adélie (Pygoscelis adeliae), Gentoo (P. papua) and Chinstrap (P. antarcticd) penguin chicks were determined with respect to body mass via respirometry in Antarctica. Resting metabolic rates of all Pygoscelid penguin chicks were similar (ANOVA p=0.91) and best described by E=0.0096 M0.98 (n=24, r2=0.97), where E is power (W) and M is mass (g). Using the results obtained here and data published in the literature, I determined a) the amount of food needed from hatching to fledging as 29.8, 31.7 and 56.4 kg per chick for Adélie, Chinstrap and Gentoo penguins, respectively and b) the average amount of food left daily to the parent after feeding the brood throughout the breeding period. Parents keep only a minimum of food for themselves just prior to the time when chicks begin forming crèches. Thereafter, nest relief intervals are increased, and the amount of food parents can keep for themselves rises. The results of both models are discussed with respect to available data on Pygoscelid penguin food requirements.
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  • 44
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    In:  Hydrobiologia, 292-293 (1). pp. 271-282.
    Publication Date: 2019-03-15
    Description: Multiple opening-closing nets of 0.05 mm mesh size were employed to study the community structure and vertical distribution of microcopepods at selected stations in the Red Sea, Arabian Sea and Eastern Mediterranean Sea down to a maximum depth of 1850 m. Calanoids, cyclopoids (Oithona and Paroithona) and poecilostomatoids (mainly Oncaea) were the 3 most abundant orders. In the epipelagic zone (0–100 m), these orders occurred at similar abundance levels, whereas in the meso- and bathypelagic zones the poecilostomatoid genus Oncaea dominated numerically by about 60–80% of all copepodids. The species diversity of Oncaea in the Red Sea is compared with preliminary results from the two adjacent regions. In the deep Eastern Mediterranean Sea, the number of species appears to be similar to that in the deep Red Sea and low as compared to the deep Arabian Sea. In this latter area an extremely speciose Oncaea fauna was found at depth below the oxygen-minimum-zone (900–1850 m). The results are related to the differences in the hydrographic conditions of these 3 areas.
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  • 45
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    In:  Boundary-Layer Meteorology, 69 (3). pp. 335-339.
    Publication Date: 2019-03-14
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  • 46
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    In:  Marine Biology, 118 (3). pp. 353-357.
    Publication Date: 2019-03-15
    Description: Many researchers use external recording or transmitting devices to elucidate the marine ecology of fish, mammals and birds. Deleterious effects of these instruments on the parameters researchers wish to measure are hardly ever discussed in the literature. Research has shown that, in penguins, volume and cross-sectional area of instruments negatively correlate with swimming speed. dive depth and breeding success, and that device colour affects bird behaviour. Here, a large (200 g, cross-sectional area 2100 mm2) streamlined device was attached to the lower back of Adélie penguins (Pygoscelis adeliae on Ardley Island, South Shetland Island in 1992) and its effects on bird swimming speed and energetics were measured in a water canal in Antarctica. Although the device was 10.5% of penguin cross-sectional area, swimming speed was reduced by only 8.3% and mean power input increased by only 5.6% while swimming. Although our streamlined device was five times more voluminous than one of our older units, the effect on swimming energetics could be reduced by 87%.
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  • 47
    Publication Date: 2019-06-11
    Description: Geochemical and Sr, Pb, O and C isotopic data are reported for carbonatite samples from five locations in southeast Brazil. Elemental abundances and δ13CPDB data (between −5.8 and −7.2‰) prove that all the samples are derived from the mantle. Dupal isotopic characteristics in the all carbonatite samples from five locations in southeast Brazil are found in this study, characteristics that have not previously been recognized in carbonatites. Brazilian carbonatites possess average values of between 101 and 145, average values of between 5.2 and 10.3, and initial Sr isotopic compositions of between 0.7046 and 0.7062. The Brazilian carbonatites comprise two groups: The northern group is coincident with the passage of the Trindade non-Dupal hotspot at ca. 80 Ma, while the southern group mainly corresponds to the passage of the Tristan de Cunha Dupal hotspot at ca. 130 Ma. Although we expected a geochemical correlation between the Brazilian carbonatites and the South Atlantic hotspots, the enriched isotopic signature (EM1) of all the carbonatite samples is similar to that of alkali basalts on Tristan de Cunha. The combined OSr isotopic diagram indicates that the southern group carbonatites have negligible or only slight crustal contamination. The northern group samples show significantly higher δ18OSMOW values of 9–14‰, more radiogenic Pb isotopic ratios, and a value of 0.705. Even if these signatures are derived from the contamination of a lower crustal component with mantle sources, it is clear that the parental magma also has inherent EM1 isotopic characteristics. The interpretation of the origin of EM1 in the Brazilian carbonatites (subcontinental lithospheric mantle vs. asthenosphere) is dependent on the model of Paraná volcanism at ca. 130 Ma, which remains controversial. One possibility is that both the northern and southern carbonatites came from enriched SCLM under a part of Gondwanaland. In this case, a hotspot would provide the thermal energy to melt the lithospheric source region for both the Paraná flood basalts and the alkali carbonatitic volcanism. Another possibility is that the source of the northern carbonatites is also the Tristan plume carbonate-rich material which had once been trapped under the crust and reactivated by the Trindade hotspot, on the assumption that Paraná volcanism at ca. 130 Ma was mainly triggered by the huge Tristan plume activity. If anything, we favour the latter and believe an asthenospheric mantle plume origin for both the ultimate carbonate source and the Dupal anomaly in the Brazilian carbonatites.
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  • 48
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    In:  In: Carbon Cycling in the Glacial Ocean: Constraints on the Ocean’s Role in Global Change. , ed. by Zahn, R., Pedersen, T. F., Kaminski, M. A. and Labeyrie, L. NATO ASI Series I: Global Environmental Change, 17 . Springer, Berlin, pp. 367-382.
    Publication Date: 2019-06-24
    Description: We reconstructed past variations in CO2 partial pressure (local PCO2) in the surface waters of the East Atlantic equatorial upwelling zone over the last 330,000 years, based on the δ13C record of the (marine) organic matter in ‘Meteor’ core 16772. To deduce the initial δ13Corganic values of plankton and the CO2 solubility in surface water, the δ13C record was adjusted for i) past variations in (winter) sea surface temperature, ii) variations in the δ13C composition of inorganic carbon dissolved in the surface waters, using the δ13C values of G. ruber (white), and iii) isotopic fractionation during the degradation of settling organic matter in the water column and on the sediment surface. The calculated paleo-PCO2 variations in the surface waters show a strong signal at the obliquity frequency and are approximately parallel to the VOSTOK ice-core record of atmospheric PCO2 over the last 140,000 years. Holocene PCO2 values varied within the range of modern local PCO2, which is 350–400 ppmv compared to a pre-industrial atmospheric pCO2 level of 280 ppmv. This positive anomaly demonstrates the persistent CO2 release from upwelled subsurface water. The glacial-to-interglacial amplitudes of local PCO2 (at the core site) exceeded those of atmospheric pCO2 by 20–60%, with values of less than 250 to 300 ppmv during cold isotopic stages, which indicate a decreased net carbon outgassing from the ocean to the atmosphere. The close correlation between high paleo-PCO2 and low paleo-nutrient contents and paleoproductivity (r=0.7–0.8) suggests that the local PCO2 variations resulted mainly from CO2 transfer by phytoplankton production, especially over the last 170,000 years.
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  • 49
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    In:  Marine Geophysical Researches, 16 (4). pp. 287-301.
    Publication Date: 2019-06-28
    Description: Vesteris Seamount is a solitary submarine volcano located at 73-degrees-30' N, 9-degrees-10' W in the Greenland Basin. Steeply rising from a base depth of 3100 m to a minimum depth of approximately 130 m and striking 030-degrees/210-degrees, the feature lies approximately 300 km east of the east Greenland margin on an otherwise nearly flat and featureless seafloor. The main body of the seamount appears to have been formed episodically, the last of which culminated about 110 000 years ago. Subsequent, lower intensity volcanic activity continued sporadically until about 25 000 years ago, as evidenced by ash layers found in cores near the base of the feature. The smoothed surfaces at the summit make it likely that the seamount actually broached the surface during the Weichselian glacial period, between 8000 and 13 000 years ago. Two multibeam bathymetric investigations aboard PFS Polarstern during ARKTIS II/4 (1984) and ARKTIS VII/1 (1990), combined with geologic sampling. single-channel seismic profiling and underwater television coverage, have resulted in a new interpretation of both the morphology and origins of the seamount. Data collected aboard Polarstern from ARKTIS II/4 (1984) have been previously reported by Hempel et al. (1991), however, when combined with the ARKTIS VII/1 (1990) data set, a more detailed interpretation of the morphology and structure was feasible. This included the elongated shape of the feature and showed the existence of several small volcanic cones on the seamount flanks.
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  • 50
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    Elsevier
    In:  Fisheries Research, 21 . pp. 1-15.
    Publication Date: 2021-01-19
    Description: The aims of this project were to improve understanding of the basic life.cycle biology, stock structure, trophic interactions and fisheries exploitation of northeast Atlantic squid, in particular the loliginids Loligo forbesi and Loligo vulgaris. Multivariate analysis of morphometric data and isozyme electrophoresis shows that L. forbesi populations from the coast of mainland Europe are fairly homogeneous, but that those from the Azores are a distinct stock. Loligo forbesi and L. vulgaris are annual species with a peak of breeding in the winter (December-May) throughout the geographical range, and one or more seasonal peaks of recruitment. Loligo are probably batch spawners. Males grow larger than females, mature about 1 month earlier and recruit earlier to the fishery. Sexual maturity occured at two distinct size classes, more obviously in males than females. Fish, including many cimmercially important species, and Crustacea, were the dominant prey of Loligo. The incidence of fish in the diet increases with squid size. Squid of all types are eaten by fish, seals, cetaceans and seabird, although quantitative estimates of consumption by these trophic levels were low. Catches of squid from northeast Atlantic waters increased over the period 1980-1990 but currently supply only a minor component of the European market for squid, the balance being made up by imports. The squid catch in the northern part of the range shows wide fluctuations in abundance by area and by season. The applicability of assessment methods for these stocks is limited by inadequate and inaccurate statistical information, and because nearly all of the catch arises by-catch from finfisheries.
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  • 51
    Publication Date: 2019-09-23
    Description: Standing stock and size composition of the zooplankton comunity (〉100 μm) were studied in four depth strata of the upper 200 m of the water column during a “Meteor” cruise to the central Red Sea and Gulf of Aden in spring 1987. The central Red Sea was divided into a northern area of higher salinity and a less saline southern part. Both areas exhibited significant differences in zooplankton abundance and standing stock. The latter increased by the ratio 1:2:3 from the northern central Red Sea to its southern part and further south to the Gulf of Aden. For size structure analysis samples were fractionated into three size classes (100 to 300, 300 to 500, 500 to 5000 μm). In the central Red Sea the smallest size was dominant whereas in the Gulf of Aden the largest size fraction played a greater relative role than in the central Red Sea. This shift in size structure of the zooplankton community from the Red Sea to the Gulf of Aden is apparently primarily related to ecosystem difference between both areas, leading to a change in species composition. In addition, size reduction of individual species common to both seas may be of some significance in the extreme environment of the Red Sea.
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  • 52
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    In:  Netherlands Journal of Sea Research, 33 (1). pp. 57-63.
    Publication Date: 2018-08-14
    Description: Studies on dormant resting cysts of the dinoflagellates Scrippsiella lachrymosa Lewis 1991 and S. trifida Lewis 1991 from Recent North Sea sediments suggest that their motile forms, which have not yet been officially recorded in this area till now, are common members of the North Sea plankton community. Cyst surveys offer avenues to overcome problems in spatial and temporal distributions and in taxonomy, and will help the compilation of a phytoplankton inventory in an area.
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  • 53
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    In:  In: Global Precipitations and Climate Change. , ed. by Desbois, M. and Desalmand, F. NATO ASI Series, 26 . Springer, Berlin, Germany, pp. 249-264. ISBN 978-3-642-79270-0
    Publication Date: 2019-09-23
    Description: The application of microwave radiometry for rainfall estimation is discussed. The first part presents a description of processes by which hydrometeors affect microwave radiation. In order to show the state-of-art of rainfall estimation with space-borne microwave radiometry five algorithms are intercompared in the second part. Two are based on scattering, one on emission and two are mixed algorithms, which include both emission and scattering. The algorithms are applied to SSM/I observations over the Atlantic Ocean. The retrieved rainfall rates by the different algorithms partly differ a great deal. The differences depend on climatic regions, demonstrating that the algorithms are probably tuned to certain atmospheric conditions. The question arises whether a globally applicable algorithm is possible at all. A severe problem is the validation of the retrieved precipitation because hardly any direct observations are available. Thus an intercomparison of algorithms is today the only way to understand the behaviour of a scheme in different weather and climate situations and assess its results.
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  • 54
    Publication Date: 2019-09-23
    Description: The present paper reviews the literature related to the life cycle of the prymnesiophyte Phaeocystis and its controlling factors and proposes novel hypotheses based on unpublished observations in culture and in the field. We chiefly refer to P. globosa Scherffel as most of the observations concern this species. P. globosa exhibits a complex alternation between several types of free-living cells (non-motile, flagellates, microzoopores and possibly macrozoospores) and colonies for which neither forms nor pathways have been completely identified and described. The different types of Phaeocystis cells were reappraised on the basis of existing microscopic descriptions complemented by unpublished flow cytometric investigations. This analysis revealed the existence of at least three different types of free-living cells identified on the basis of a combination of size, motility and ploidy characteristics: non-motile cells, flagellates and microzoospores. Their respective function within Phaeocystis life cycle, and in particular their involvement in colony formation is not completely understood. Observational evidence shows that Phaeocystis colonies are initiated at the early stage of their bloom each by one free-living cell. The mechanisms controlling this cellular transformation are still uncertain due to the lack of information on the overwintering Phaeocystis fomms and on the cell type responsible for colony induction. The existence of haploid microzoospores released from senescent colonies gives however some support to sexuality involvement at some stages of colony formation. Once colonies are formed, at least two mechanisms were identified as responsible of the spreading of colony form: colony multiplication by colonial division or budding and induction of new colony from colonial cells released in the external medium after colony disruption. The latter mechanism was clearly identified, involving at least two successive cell differentiations in the following sequence: motility development, subsequent flagella loss and settlement to a surface, mucus secretion and colony formation, colonial cell division and colony growth. Aggregate formation, cell motility development and subsequent emigration from the colonies, release of non-motile cells after colony lysis on the other hand, were identified as characteristics for termination of Phaeocystis colony development. These pathways were shown to occur similarly in natural environments. In the early stages of the bloom however, many recently-formed colonies were found on the setae of Chaetoceros spp, suggesting this diatom could play a key-rôle in Phaeocystis bloom inception. Analysis of the possible environmental factors regulating the transition between the different phases of the life cycle, suggested that nutrient status and requirement of a substrate for attachment of free-living cells would be essential for initiation of the colonial form. Physical constraints obviously would be important in determining colony shape and fragmentation although autogenic factors cannot be excluded. Some evidence exists that nutrients regulate colony division, while temperature and nutrient stress would stimulate cell emigration from the colonies.
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  • 55
    Publication Date: 2018-08-14
    Description: In March/April 1991 hydrographic parameters (salinity, temperature) and hydrochemical parameters (concentrations of phosphate, nitrate, nitrite, ammonia, silicate and pH) were measured continuously in the surface water of the Baltic Sea and the North Sea. The hydrographic parameters were determined by means of a TS,pH probe and the chemical parameters were determined by means of an Auto Analyser. The cruise track through the Baltic Proper, the western Baltic Sea, the transition area to the North Sea and the North Sea with the mouth of the river Elbe was around 2050 nautical miles long and included some 2100 data-points. The different phases of the Baltic Sea's spring diatom bloom were inferred from the different nutrient concentrations measured; a comparison with the hydrographic data revealed that the bloom was largely unconnected to the hydrography. The same situation was encountered in the North Sea except that the spring bloom there had already reached a later phase. In those regions of the Baltic Sea where a plankton bloom had already occurred or was still under way, strong patchiness of the hydrochemical parameters was also observed; it was sometimes possible to relate it to the topography. This patchiness was far less pronounced in the North Sea and in regions of the Baltic Sea where conditions were still wintry. This paper discusses the advantages and possible applications of the method of continuous measurement of hydrochemical parameters across large areas with high temporal and spatial resolution.
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  • 56
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    Elsevier
    In:  Continental Shelf Research, 14 (4). pp. 385-399.
    Publication Date: 2018-08-17
    Description: The Bass Strait cascade is a wintertime downwelling caused by cooling of the shallow waters of Bass Strait. During winter, a front separates the cold shelf water from the waters of the Tasman Sea. Continuous horizontal bands of downwelled water leading oceanward beneath the front imply that it can be transgressed near the bottom anywhere along its length. However, by far the greatest volume crosses at a breach at the northern end. Measured currents in eastern Bass Strait fit a predictable pattern: eastward toward the front, then as the front is approached, swinging north towards the breach. Flow northwards along the slope after downwelling is quantified using a simple analytic model. Cascade water found in the “far-field” was found only in small patches. One such patch was found to possess motion independent from the mean flow in which it was embedded.
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  • 57
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    In:  Meteorology and Atmospheric Physics, 54 (1-4). pp. 157-171.
    Publication Date: 2018-08-17
    Description: A method is presented to infer cloud liquid water path (LWP in kg/m2) over the ocean from passive microwave measurements of SSM/I. The algorithm to retrieve LWP is based on simulated satellite observations. They are calculated with a radiative transfer model applied to about 3000 radiosonde ascents over the Atlantic Ocean. Since radiosonde observations do not contain direct information about cloud water and ice, these parameters are parameterized based on relative humidity and temperature using modified adiabatic liquid water density profiles. A multiple linear regression is applied to the simulated radiances and the calculated LWP to derive the algorithm. The retrieval accuracy based on the regression analysis including instrumental noise is 0.03 kg/m2. Validation of the LWP-algorithm was pursued through a comparison with measurements of a ground-based 33 GHzmicrowave radiometer on board of R.V. “Poseidon” during the International Cirrus Experiment 1989 at the North Sea (ICE'89). The LWP values agree within the range of uncertainty caused by the different sampling characteristics of the observing systems. The retrieval accuracy for clear-sky cases determined using colocated METEOSAT data over the North Sea is 0.037 kg/m2 and confirms the accuracy estimated from regression analysis for the low liquid water cases. The algorithm was used to derive maps of monthly mean LWP over the Atlantic Ocean. As an example the Octobers of the 5 years 1987–1991 were selected to demonstrate the interannual variability of LWP. The results were compared with the cloud water content produced by the climate model ECHAM-T2 from the Max-Planck-Institut Hamburg. Observations during ICE'89 were used to check the accuracy of the applied radiative transfer model. Brightness temperatures were calculated from radiosonde ascents launched during the overpass of DMSP-F8 in cloud-free situations. The channel-dependent differences range from about −2 to 3 K. The possibility to identify different cloud types using microwave and infrared observations was examined. The main conclusion is that simultaneous microwave and infrared measurements enable the separation of dense cirrus and cirrus with underlying water clouds. A classification of clouds with respect to their top heights and LWP was carried out using a combination of SSM/I derived LWP and simultaneously recorded Meteosat IR-data during ICE'89.
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  • 58
    Publication Date: 2018-03-21
    Description: This chapter throws the attention on the meiobenthos of the deep northeast Atlantic. The main purpose of this chapter is to summarize new results from an area lying between 15°N and 53°N and extending from the continental margin of western Europe and northwest Africa to the Mid-Atlantic Ridge. It considers first the nature and scope of meiofaunal research in the northeast Atlantic and then discuss the environmental parameters, which are believed to influence meiofaunal organisms. This chapter then discusses the various types and scales of pattern observed among meiofaunal populations within the study area, progressing from the large-scale bathymetric and latitudinal trends and then to small-scale horizontal patterns within particular areas. Faunal densities and faunal composition are considered separately and compared with data from other regions. This chapter also deals with the distribution of meiofauna within sediment profiles and the temporal variability of populations. This chapter concludes by discussing the recent review of deep-sea meiofauna, which focused mainly on the abundance and biomass data from different oceans and on the relationship between the biomass of the meiofauna and that of other faunal components
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  • 59
    Publication Date: 2018-03-08
    Description: The 10Be records of four sediment cores forming a transect from the Norwegian Sea at 70°N (core 23059) via the Fram Strait (core 23235) to the Arctic Ocean at 86°N (cores 1533 and 1524) were measured at a high depth resolution. Although the material in all the cores was controlled by different sedimentological regimes, the 10Be records of these cores were superimposed by glacial/interglacial changes in the sedimentary environment. Core sections with high 10Be concentrations ( 〉 1 · 109 at/g) are related to interglacial stages and core sections with low10Be concentrations ( 〈 0.5 · 109 at/g) are related to glacial stages. Climatic transitions (e.g., Termination II, 5/6) are marked by drastic changes in the 10Be concentrations of up to one order of magnitude. The average 10Be concentrations for each climatic stage show an inverse relationship to their corresponding sedimentation rates, indicating that the 10Be records are the result of dilution with more or less terrigenous ice-rafted material. However, there are strong changes in the 10Be fluxes (e.g., Termination II) into the sediments which may also account for the observed oscillations. Most likely, both processes affected the 10Be records equally, amplifying the contrast between lower (glacials) and higher (interglacials) 10Be concentrations. The sharp contrast of high and low 10Be concentrations at climatic stage boundaries are an independent proxy for climatic and sedimentary change in the Nordic Seas and can be applied for stratigraphic dating (10Be stratigraphy) of sediment cores from the northern North Atlantic and the Arctic Ocean
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  • 60
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    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 41 (4). pp. 721-739.
    Publication Date: 2017-07-21
    Description: In situ measurement of fluid flow rates from active margins is an important parameter in evaluating dissolved mass fluxes and global geochemical balances as well as tectonic dewatering during developments of accretionary prisms. We have constructed and deployed various devices that allow for the direct measurement of this parameter. An open bottom barrel with an exhaust port at the top and equipped with a mechanical flowmeter was initially used to measure flow rates in the Cascadia accretionary margin during an Alvin dive program in 1988. Sequentially activated water bottles inside the barrel sampled the increase of venting methane in the enclosed body of water. Subsequently, a thermistor flowmeter was developed to measure flow velocities from cold seeps. It can be used to measure velocities between 0.01 and 50 cm s−1, with a response time of 200 ms. It was deployed again by the submersible Alvin in visits to the Cascadia margin seeps (1990) and in conjunction with sequentially activated water bottles inside the barrel. We report the values for the flow rates based on the thermistor flowmeter and estimated from methane flux calculations. These results are then compared with the first measurement at Cascadia margin employing the mechanical flowmeter. The similarity between water flow and methane expulsion rates over more than one order of magnitude at these sites suggests that the mass fluxes obtained by our in situ devices may be reasonably realistic values for accretionary margins. These values also indicate an enormous variability in the rates of fluid expulsion within the same accretionary prism. Finally, during a cruise to the active margin off Peru, another version of the same instrument was deployed via a TV-controlled frame within an acoustic transponder net from a surface ship, the R.V. Sonne. The venting rates obtained with the thermistor flowmeter used in this configuration yielded a value of 4411 m−2 day−1 at an active seep on the Peru slope. The ability for deployment of deep-sea instruments capable of measuring fluid flow rates and dissolved mass fluxes from conventional research vessels will allow easier access to these seep sites and a more widespread collection of the data needed to evaluate geochemical processes resulting from venting at cold seeps on a global basis. Comparison of the in situ flow rates from steady-state compactive dewatering models differ by more than 4 orders of magnitude. This implies that only a small area of the margin is venting and that there must be recharge zones associated with venting at convergent margins
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  • 61
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    Elsevier
    In:  Marine Chemistry, 47 . pp. 115-125.
    Publication Date: 2018-03-02
    Description: A widely used degassing method for methane in seawater employing vacuum was tested and subsequently improved. It yielded 62 ± 3.8% of the total dissolved methane, hence a reproducible correction factor was established. The method was then applied to measure CH4 in the sea-air boundary layer and simultaneously in the overlying air along two transects in the eastern Equatorial Pacific off Peru in March of 1992. The results showed surprising small-scale reversals of the methane exchange between ocean and atmosphere in this region. Generally the ocean acted as a source of methane but also methane uptake by the ocean was found. This was mainly a consequence of high CH4 concentrations in the air which deviated considerably from the long-term and large-scale average. If applied to the flux rate calculations, the observed variabilities indicate that both rate and direction of the methane flux through the air-sea interface vary considerably depending on the atmospheric CH4 content. The implications are that even ocean areas with high concentrations of dissolved CH4 can be considerably weaker sources than would be expected on the basis of 1.7 ppmv mean atmospheric methane content. Based on improved simultaneous analyses of both air and water samples, the ocean-atmosphere flux of methane would therefore be more dynamic than previously thought.
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  • 62
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    In:  Oceanology, 34 (3). pp. 373-379.
    Publication Date: 2020-11-19
    Description: Some species of wide-spread tropical squids and pelgic octopuses (Histioteuthis hoylei, Alloposus mollis and others), based on beak findings in sperm whale stomachs, were common in the 1950s and early 1960s and widely distributed along the Kuril' Islands, eastern Kamchatka, in the Bering Sea, near the Aleutian Islands and the Gulf of Alaska, but later they were never recorded north of northwastern Honshu or southeast of the southern Kuril's. In 1990-1992 the squid Watasenia scintillans extended north to the middle Kuril's and, in smaller quantities, to the northern Kuril's while H. hoylei extended to the western Bering Sea. In the summer of 1992, Ancistrocheirus lesueurii, Mastigoteuthis dentata?, Eledonella pygmaea, and Allopsus mollis were also caught off the Shikotan, Kunashir, and Iturup Islands. A. lesueurii and E. pygmaea were caught in the Russian EEZ for the first time. We discuss why the warm-water species appear in the Russian Far Eastern seas again, after a long period of absence.
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  • 63
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    In:  Springer, Berlin, Germany, 274 pp. ISBN 3-540-57676-2
    Publication Date: 2012-02-28
    Type: Book , NonPeerReviewed
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  • 64
    Publication Date: 2019-05-14
    Description: The Cenozoic sediments sampled in ODP Leg 104 on the Vøring Plateau show a distinct variability of the total organic carbon content (TOC) and the accumulation rates of TOC. Based on the geochemical and organic-petrographic characterization of the sedimentary organic matter (OM), the allochthonous and autochthonous proportion of the OM could be quantified.The results clearly demonstrate that high TOC percentages and TOC accumulation rates in Cenozoic sediment sections display a generally high input of allochthonous organic matter. Oxidized and partly well-rounded organic particles built up the main portion of OM within the Miocene, TOC-rich sediments. The most probable source of this oxidized OM are reworked sediments from the Scandinavian shelf. Changes in the input of these organic particles are to some degree correlative with sea-level changes.The Cenozoic accumulation of autochthonous OM is low and does not reveal a clear variation during the Miocene and early Pliocene. In spite of a high accumulation rate of biogenic opal during the Early Miocene, the accumulation rate of autochthonous TOC is low. The autochthonous particle assemblage is dominated by relatively inert OM, like dinoflagellate cysts. This points to an intensive biological and/or early diagenetic degradation of the marine OM under well oxidized bottom water conditions during the last 23 Myr. Nevertheless, a continuation of marine OM degradation during later stages of diagenesis cannot be excluded.A prominent dominance of allochthonous OM over autochthonous is documented with the beginning of the Pliocene. At 2.45 Ma the episodic occurrence of ice-rafted, thermally mature OM reflects the onset of the glacial erosion of Mesozoic, coal and black shale bearing sediments on the Scandinavian and Barents Sea shelves. The first occurrence of these, in view of the actual burial depth, thermally overmature OM particles is, therefore, a marker for the beginning of the strong Scandinavian glaciation and the advance of the glacial front toward the shelves.
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  • 65
    Publication Date: 2018-03-21
    Description: In order to assess recent submarine volcanic contributions to the sediments from the active Kolbeinsey Ridge, surface samples were analyzed chemically. The contribution of major and trace elements studied differ within the study area. A statistical analysis of the geochemical variables using factor analysis and cluster method allows to distinguish possible sample groups. Cluster method identifies three distinct sediment groups located in different areas of sedimentation. Group 1 is characterized by highest contents of Fe2O3, V, Co, Ni, Cu and Zn demonstrating the input of volcaniclastic material. Group 2 comprises high values of CaCO3, CaO and Sr representing biogenic carbonate. Group 3 is characterized by the elements K, Rb, Cs, La and Pb indicating the terrigenous component. The absolute percentage of the volcanic, biogenic and terrigenous components in the bulk sediments was calculated by using a normative sediment method. The highest volcanic component (〉 60% on a carbonate free basis) is found on the ridge crest. The biogenic component is highest (10–30%) in the eastern part of the Spar Fracture Zone influenced by the East Iceland Current. Samples from the western and southeastern region of the study area contain more than 90% of terrigenous component which appears to be mainly controlled by input of ice-rafted debris.
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  • 66
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    In:  Characteristic Multifractal Element Distributions in Recent Bioactive Marine Sediments | Fractals and Dynamic Systems in Geoscience
    Publication Date: 2022-03-21
    Type: info:eu-repo/semantics/bookPart
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  • 67
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    In:  From No-Man's Land to a Congested Paradise: An Environmental History of Mauritius | Population-Development-Environment: Understanding their Interactions in Mauritius
    Publication Date: 2022-03-21
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  • 68
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    In:  Modeling the Water Systems | Population-Development-Environment: Understanding their Interactions in Mauritius
    Publication Date: 2022-03-21
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  • 69
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    Springer
    In:  Population-Development-Environment: Understanding their Interactions in Mauritius
    Publication Date: 2022-03-21
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  • 70
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    Elsevier
    In:  Amsterdam, Elsevier, vol. 65, no. ALEX(01)-FR-77-01, AFTAC Contract F08606-76-C-0025, pp. 95-104, (ISBN: 0-08-044051-7)
    Publication Date: 1993
    Keywords: Textbook of geophysics ; GeodesyY ; Geothermics ; Planetology ; ConvolutionE
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  • 71
    Publication Date: 2020-07-14
    Description: Horizontal starch gel electrophoresis was used to investigate levels of genetic differentiation between four samples of the nominate squid species Martialia hyadesi Rochbrune and Mabille, 1889, obtained from regions of the Patagonian Shelf and Antarctic Polar Fron-tal Zone over 1000 km apart. M. hyadesi is an ecologically important South Atlantic ommastrephid squid and it is probable that, in the future, fishing effort will be increasingly directed towards this species. Details regarding the population structure of the species are therefore required. In comparison with the other three samples of M. hyadesi, one of the samples from the Patagonian Shelf (PAT 89II) exhibited fixed allelic differences at 16 of the 39 enzyme loci which were resolved (genetic identity, I=0.51). This high level of genetic differentiation contradicts the apparent morphological similarity between samples, indicating the presence of a cryptic or sibling congeneric species. Deviations from Hardy-Weinberg equilibrium and significant differences in allele distribution were also detected within and between the other three putative M. hyadesi samples, suggesting that the species fails to maintain effective panmixia across its geographical range. The occurrence of both temporal (1986 cf. 1989) and geographic structuring within the species complex is consequently indicated, caused possibly by an overlap of reproductively isolated stocks (stock mixing) outside their respective breeding areas. Low levels of genetic variability were detected throughout the samples examined, estimates of average heterozygosity per locus within the two species detected being in the order of 0.01 and 0.002. These values are discussed in relation to levels of genetic variability reported for other squid species, and in comparison with values typically expected for marine invertebrates.
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  • 72
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    In:  Marine Biology, 115 (1). pp. 143-150.
    Publication Date: 2018-03-21
    Description: Lower and upper survival temperatures of microthalli of 25 species of South American Phaeophyceae isolated from central Peru (14°S) to the Canal Beagle (55°S) were determined using 2-wk exposure for the upper and 4-wk exposure for the lower limit. All species survive 4 wks at -2°C. With respect to the upper limit, species reported only from southernmost South America tolerate 19.9 to 24.5°C (n=8), and species occurring from Cape Horn to central Chile 24.6 to 27.4°C (n=7). Three species that occurred as far north as northern Chile and Peru before the 1982–1983 El Niño event, and whose northern limit was dramatically shifted southwards in 1983, tolerate 20.8 to 25.3°C, whereas five species that have survived in Peru tolerate 25.6 to 28.5°C. Tinocladia falklandica which tolerates 27.8 to 28.1°C but lives only in southernmost South America and Striaria attenuata, which tolerates 31.6 to 31.9°C but occurs at ca. 42°S, are exceptional. Their high temperature tolerance may have no adaptive value in South America. They are restricted to the cold-temperate region due to low temperature requirements for reproduction or for reasons yet unknown. In general, the northern distributional limits of the Phaeophyceae studied along the temperate Pacific coast of South America are reproduction boundaries, except in El Niño years when they are redefined according to the species' upper suvival limits. Temperature tolerance of isolates from northern Chile and Peru agrees well with maximum temperatures reached during the 1983 El Niño.
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  • 73
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    In:  Fresenius' Journal of Analytical Chemistry, 345 (12). pp. 773-779.
    Publication Date: 2018-03-23
    Description: During a cruise in the Baltic Sea in March/April 1991, dissolved lipids were concentrated from acidified sea water by adsorption on reversed phase material; the free fatty acids in the lipids were isolated. Titration of the acids with 0.01 mol/l methanolic KOH resulted in a very poor titration curve; assessing total concentration of organic acids in sea water by base titration appears to be impractical. After derivatization with p-phenylphenacyl bromide under crown ether catalysis the fatty acids were analyzed by micro-bore HPLC with UV-detection and comparison with standard reference substances. Some unknown fatty acids were characterized by GC/MS. Total concentrations were in the range from 1 to 4.5 nmol/l. They were the same in parallel samples liquid/liquid extracted with dichloromethane. The HPLC spectra of the fatty acids in both kinds of samples were also quite similar. This confirms earlier observations that adsorptive concentration of dissolved fatty acids and non-polar lipids from sea water is as effective as liquid/liquid extraction. Higher amounts of fatty acids can be concentrated by adsorption from large water volumes, thus lowering detection limits. Palmitic acid had by far the highest concentration in every sample followed by myristic acid, lauric acid, and stearic acid. Palmitoleic acid and oleic acid were the most abundant unsaturated acids. The other saturated and unsaturated acids had medium to low concentrations.
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  • 74
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    Elsevier
    In:  Marine Pollution Bulletin, 26 (3). pp. 152-155.
    Publication Date: 2018-03-22
    Description: Skin and hair samples of harbour seals (Phoca vitulina) found dead along the west coast of northern Germany in 1988 were analysed for total mercury, cadmium and lead. Cadmium and lead concentrations were below the detection limit in most skin samples. The mercury content of the hair (median: 23.1 μg g−1 wet wt) was several magnitudes higher than the mercury content of the skin (0.27 μg g−1 wet wt). Mercury concentrations in hair samples were significantly higher than lead concentrations (0.54 μg g−1 wet wt), which significantly exceeded cadmium levels (0.09 μg g−1 wet wt). Female seals revealed lower cadmium concentrations in the hair than male seals. Accumulations of metals with age were observed for cadmium and lead in hair samples and for mercury in skin samples of male seals. A connection between metal accumulation and pigmentation or rather moult was clearly recognizable.
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  • 75
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    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 40 (2). pp. 267-291.
    Publication Date: 2018-03-22
    Description: The spreading of Mediterranean Water (MW) released through the Straits of Gibraltar is studied with hydrographic data, oxygen, nutrients and for the first time with chlorofluoromethane (CFM, compounds F11 and F12) distributions along seven sections in the Gulf of Cadiz, and with measurements in the Western Alboran Sea and west of the Gulf. The properties of MW entering the Gulf are deduced from CFM-salinity correlations east and west of the Straits as well as from property-depth profiles in the Western Alboran Sea. At the time of the survey, the outflow originated from depths above the salinity maximum of the Intermediate Water in the Alboran Sea. It turned out that the F11/F12 ratio of the outflow is equal to the ratios found in the Atlantic water in the Gulf of Cadiz; thus the ratio carries no time information in the region. A model is developed to describe mixing of the MW undercurrent with overlying North Atlantic Central Water (NACW) from different depths. The contribution of each layer to the mixing is parameterized by a weighting factor, which has to satisfy the balances of potential temperature (θ), CFMs, oxygen and nutrients in the MW undercurrent. It is shown that entrainment of water from shallower depths into the undercurrent is important near the Iberian Continental Shelf. Farther west and south, the undercurrent mainly mixes with water from near the salinity minimum of the NACW. For regions where the undercurrent has left the bottom, additional mixing with North Atlantic Deep Water (NADW) has to be taken into account. The percentage of MW in the undercurrent decreases from 76% hear the Straits to about 34% at 7°30′W for the lower core (MI) and about 22–24% for the upper core (Mu). Assuming an outflow of undiluted MW through the Straits of 1.0 Sv, the transport of the undercurrent can be calculated by determining an average dilution factor for each section. The undercurrent transports 2.0 Sv just west of the Straits and 3.6 Sv leave the Gulf of Cadiz. At 36°N, 9°54′W, a meddy with unusually high temperatures and salinities below 500 m was found, covering the density range for both cores, Mu and Ml. From the θ−S characteristics and the evaluated mixing scheme of the meddy it appears to have formed near 7°W in the Gulf, a region up to now not proposed in the literature, and moved westward without much further mixing.
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  • 76
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    Elsevier
    In:  International Journal for Parasitology, 23 (6). pp. 749-755.
    Publication Date: 2018-03-23
    Description: In April 1990, 488 marine fish belonging to 30 species from central Phillipine waters were examined for flesh parasitic infections that may affect their consumability. One species of hemirhamphids and 3 species of belonids harboured plerocercoids of Otobothrium penetrans Linton, 1907 (Proceedings of the U.S. National Museum33, 85–126). This is the first record of this parasite from Pacific fish species. The highest intensity of infection found was 8 in Tylosurus crocodilus. Most of the larvae were located between the dorsal spines of the vertebral column, only 32% were found in the fillets. Based on the present material we give a description of the plerocercoid stage of the species using scanning electron microscopy of the armature and morphometrical measurements. Comparison to results from earlier findings of O. penetrons by Linton (1907; 1924, Proceedings of the U.S. National Museum64, 1–114) and to O. kurisi by Shields (1985, International Journal for Parasitology15: 635–643) lead to the conclusion that the latter species is a synonym for O. penetrans.
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  • 77
    Publication Date: 2018-03-21
    Description: Nine large box cores collected in the western Greenland-Iceland-Norwegian (GIN) Sea were analyzed for calcium carbonate content and coarse fraction components. Stratigraphic control is based on oxygen isotope records performed on four of the cores. All cores were correlated using oxygen and carbon isotope data, fluctuations in calcium carbonate content, coarse terrigenous particle content and volcanic ash beds. Glacial and interglacial cycles are documented by a number of terrigenous particle events and differentiated calcium carbonate production which can be correlated to major paleoceanographic and paleoclimatic shifts. In the older core sections, extensive deposition of ice-rafted detritus (IRD) persisted until about oxygen isotope stage 9 and document a relatively stable environment in this area, strongly influenced by cold surface water masses. The following interval was characterized by variations in the general surface water circulation pattern, although high amounts of IRD are still present in Iceland Sea sediments. Pronounced shifts in terrigenous input and pelagic carbonate records were identified close to the oxygen isotope stage Full-size image (〈1 K) and Full-size image (〈1 K) boundaries, indicating massive melting of icebergs in the western GIN Sea. These enormous inputs of debris were followed by an increase in calcium carbonate production caused by maximum intrusion of warm Atlantic surface waters. Relatively high calcium carbonate contents also show that only little dilution by fine-grained material and a minimum of ice melting occurred during these warm phases. During oxygen isotope stage 5, conditions were more uniform indicating a less pronounced westward penetration of Atlantic waters as compared to the Holocene. The last glacial (stages 4-2) is characterized by the occurrence of “Heinrich”-like events, although high IRD contents were present throughout this interval. A distinct contrast between the northernmost cores and the cores in the south is indicative of a rather strong westward penetration of Atlantic water in the north and of an area dominated by cold water east of the Kolbeinsey Ridge during the Holocene. However, conditions west of Jan Mayen seem to have remained constantly dominated by cold surface waters throughout the whole time investigated.
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  • 78
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    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 40 (3). pp. 783-800.
    Publication Date: 2018-03-05
    Description: Horizontal distribution of myctophid fishes were studied from two transects in the Arabian Sea in 1987. Species numbers exhibited a south-north decline in diversity, with only half of the fish taxa occupying the northeastern region. Diaphus arabicus was the dominant species both in the south and north. All recorded myctophid fish species migrate in a diel pattern, residing during daytime at depths of extremely low oxygen levels (〈0.1 ml O2 1−1) and foraging in the oxygen-rich surface layer at night. Feeding patterns were determined for the six most abundant myctophid species. All species appeared to be opportunistic predators that prey on a comparatively narrow food spectrum consisting principally of small to medium sized copepods. Numerically, non-calanoid copepods (with Oncaea conifera and O. venusta dominating) made up to 70% of the diet of D. arabicus and Bolinichthys longipes. Of the 26 calanoid copepod species identified from the six myctophid taxa, the genera Euchaeta, Pleuromamma and Candacia generally dominated in the stomachs, with P. indica constituting between 21 and 95% (by numbers) of the calanoid copepod prey.
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  • 79
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    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 40 (6). pp. 1155-1168.
    Publication Date: 2018-03-05
    Description: Particulate fluxes of aluminium, cadmium, cobalt, copper, iron, manganese, nickel, phosphorus, lead, vanadium and zinc in the northeast subtropical Atlantic Ocean have been determined from sediment trap samples collected between 1 December 1986 and 30 April 1987 at 1020 and 4120 m below the ocean surface. The fluxes of most elements (except Cd and P) show small variations between the different layers, and are closely associated with the vertical transport of aluminium. Elemental composition and flux rates suggest that aerosol loadings from northeast trade winds are the major contributor of these elements to depositing material. Extremely low fluxes of copper, lead and zinc also indicate that anthropogenic perturbations are of insignificant importance in this region.
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  • 80
    Publication Date: 2018-03-05
    Description: Within the framework of the JGOFS Pilot Study in 1989 mesozooplankton (0.2–20 mm) was sampled by means of a Hydro-Bios multinet in five depth strata (0–25, 25–50, 50–100, 100–200, 200–500 m) during four Lagrangian drift experiments of 8–14 days' duration at 18, 33, 46 and 58°N, to follow the seasonal progress of the phytoplankton spring bloom development in the northeast Atlantic. Mesozooplankton standing stock, measured as dry weight and ash-free dry weight, increased by a factor of about 6 from 18 to 58°N. Day/night differences amounted to 10–20% of the average and were—with one exception at 18°N—not statistically significant. Using the data on weight-specific respiration rates measured by colleagues on the same cruise, the ingestion rates and potential community grazing of mesozooplankton on phytoplankton within the upper 100 m of the water column were calculated. During all four drift experiments, quasi-steady-state conditions were observed in phyto- and zooplankton standing stock, primary production and daily sedimentation at 100 m depth. The maximum potential grazing rate by mesozooplankton accounted for about half of the daily primary production. Since sedimentation of fresh phytoplankton was negligible, it is concluded that the grazing pressure exercised by mesozooplankton together with micro- and nanozooplankton was responsible for keeping the phytoplankton standing stock at a more or less constant level during the investigated spring bloom in the four areas. Particle flux was thus dominated by zooplankton faecal material.
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  • 81
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    In:  Journal of Chromatography A, 642 (1-2). pp. 425-434.
    Publication Date: 2019-02-27
    Description: Accurate congener-specific determination of chlorobiphenyl congeners (all 209 congeners) is finally possible with the use of multidimensional gas chromatography-electron-capture detection techniques. The effectiveness of this technique for environmental analyses is enhanced by ultraclean laboratory practices, non-destructive extraction and clean-up steps and the use of low-volume, high-efficiency HPLC separation for various classes of organic contaminants. In the light of these new developments conventional procedures for chlorobiphenyl analysis are evaluated.
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  • 82
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    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 40 (3). pp. 711-735.
    Publication Date: 2018-03-05
    Description: The productivity regime and size structure of phytoplankton are described for three different epipelagic systems in the Arabian Sea during the inter-monsoon period in spring 1987: (1) the coast of Oman; (2) the central Arabian Sea; and (3) the shelf off Pakistan. These results are related to the functioning of the specific ecosystem. Off the coast of Oman, the transition from a surface maximum of autotrophic biomass and production to a more oligotrophic system, with a chlorophyll subsurface maximum, was observed. Concomitantly, the size spectrum changed towards a higher significance of picoplankton. In the central Arabian Sea, a typical oligotrophic system with a pronounced subsurface maximum of autotrophic biomass and primary production was encountered. Here, the epipelagic system could be divided into two distinct sub-systems: the surface layer “regenerated” production, the predominance of picophytoplankton and minor losses due to sedimentation, thus a “closed” system; and the subsurface maximum layer at the nutricline characterized by higher sedimentation losses and more diatoms. Both sub-systems showed about the same productivity, the turnover in the surface layer having been much greater than in the subsurface maximum. The system on the shelf off Pakistan is seen as a decay stage of the open ocean system when water from offshore is transported onto the shelf during the onset of monsoon winds.
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  • 83
    Publication Date: 2018-03-21
    Description: Crossing studies revealed an intraspecifìc sterility barrier on the level of zygote formation between Japanese Sphaerotrichia divaricata and isolates of the same species from the Northeast Pacific and the North Atlantic. Because no consistent morphological differences exist between sporophytes from Japan and other areas, we propose not to distinguish the intersterile populations as different species. Japanese Sphaerotrichia and isolates from a recently detected population in the Étang de Thau, French Mediterranean coast, are interfertile. The crossing studies support the assumption that this Mediterranean population is a recent introduction from Japan.
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  • 84
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    In:  Polar Biology, 13 (5). pp. 355-357.
    Publication Date: 2020-06-10
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  • 85
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    In:  Polar Biology, 13 (6). pp. 373-376.
    Publication Date: 2020-06-10
    Description: Regurgitations were collected from 41 black-browed albatross adults feeding chicks at Bird Island (54°S 38°W), South Georgia in February 1986. The samples were sorted into recognisable food categories and weighed. Cephalopods were identified by means of the lower beak, or in some cases the gladius, and allometric equations were used to calculate mantle length and wet body weight represented by beaks. The samples contained 35.5%Euphausia superba, 30.9% cephalopods and 27.1% fish, by weight. A total of 21 samples contained recognisable cephalopod remains and 20 contained specimens that could be identified. In all, 50 cephalopod specimens, representing an estimated 6,866 g wet weight, were identified. The diet was dominated in terms of numbers, weight and percent occurrence by the ommastrephid squidMartialia hyadesi, and in most cases the entire squid was present with only partial digestion of the skin and arm armature. The cranchiid squidGaliteuthis glacialis was the only other cephalopod of numerical importance but no soft parts were present suggesting that, although significant in the diet of the adults, this species was not being fed to chicks. One specimen each ofGonatus antarcticus, Chiroteuthis sp.,Histioteuthis sp. B. and the octopodidPareledone polymorpha were also present. The cephalopod composition of the diet corresponded closely with a collection made 10 years earlier. The commonest species in the bird's diet,M. hyadesi, has not been found in net and jig samples at South Georgia although it has been taken from the Antarctic Polar Frontal Zone to the west of the Island. The presence of almost complete, undigested, specimens ofM. hyadesi in the bird's diet indicates that it occurs relatively close to South Georgia.M. hyadesi preys largely on myctophid fishes, which themselves prey on small zooplankters, so a significant component of the black-browed albatross diet depends on a food chain which largely by-passesE. superba.
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  • 86
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    Springer
    In:  Marine Biology, 117 . pp. 495-500.
    Publication Date: 2017-04-28
    Description: The accumulation of parasites in a fish host is modelled as a function of the total amount of prey consumed. The accumulated parasite load is then expressed as a function of fish length so that the asymptotic growth, L∞, of any population of commonly infected fish can be estimated. Estimates of L∞ are obtained for orange roughy (Hoplostethus atlanticus), albacore tuna (Thunnus alalunga) and the New Zealand southern arrow squid (Nototodarus sloanii).
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  • 87
    Publication Date: 2018-03-07
    Description: In February 1988, 60 near surface samples were taken on a track between 2°W in the English Channel, the Pentland Firth and the inner German Bight. Determinations were made on filtered and unfiltered samples. Concentrations of dissolved metals in the North Sea normalized to a salinity of 34.5 were Al 31, Cd 0.13, Co 0.13, Cu 3.4, Mn 6.2 and Ni 3.9 nM. In July 1984 the equivalent concentrations were Al 11, Cd 0.15, Co 0.15, Cu 4.3, Mn 12 and Ni 3.6 nM. Distinct regional differences were detectable which can be related to the origin of the water, differing river inputs, and solution-solid phase exchange reactions. The degree of the influence of exchange reactions was investigated through the concept of Kd, the distribution coefficient. A Kd of 105 ml g−1 for Al is consistent with other observations and explains the relatively high concentrations of dissolved Al detected in the English Channel on this cruise. The data suggest a higher Kd for Mn approaching 106 ml g−1. The high Mn Kd coupled to higher suspended sediment loads in winter may be sufficient to explain the lower concentration of dissolved Mn in winter. Comparison of concentrations across the shelf break suggests that for all the metals studied, the European Shelf is a source of dissolved metals to the deep sea. Calculations based on the limited available data indicate that this export is of similar magnitude to the fresh water input of dissolved metals.
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  • 88
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    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 40 (1-2). pp. 91-114.
    Publication Date: 2018-03-05
    Description: An overview is given of the multinational investigations carried out at 47°N 20°W for the period 24 April–31 May, with the main emphasis on the succession of plankton communities and the flux of organic carbon through various plankton components. The depth of the upper mixed layer decreased rapidly after 25 April, triggering the start of the spring bloom that developed within a 2-week period. Chlorophyll a stocks integrated to 80 m water depth reached peak concentrations during the first 10 days in May. The observed decline was partly due to the seasonal development, but also may have been influenced by changes in water masses associated with a cyclonic eddy. Primary production ranged from 50 to 150 mmol C m−2 day−1 with highest values in the first half of May. After the first bloom phase, dominated by diatoms, nanophytoplankton gained more importance as primary producers when silicate was depleted. Stocks of bacteria, microzooplankton and mesozooplankton increased in the second half of May. Bacterial production averaged 30% of primary production and probably metabolized a large amount of dissolved organic carbon (DOC) per day, but due to uncertain carbon conversion efficiencies total bacterial carbon consumption is difficult to estimate. Largely daily changes in the DOC standing stock could not be reconciled with the measured primmary production and are probably an expression of spatial rather than temporal variations. Microzooplankton was found to consume around 64% of primary production in the second half of May. Grazing estimates for mesozooplankton varied but seem to be small (〈5% of primary production) for most of the investigation period. The small mesozooplankton size classes (〈1 mm) dominated biomass and grazing. Vertical particulate organnic carbon (POC) flux measured by sediment traps in 150 m depth was around 9.8 mmol C m−2 day−1 representing approximately 11% of primary production. The spring bloom pulse of particle flux reached the deep ocean and benthos 4–6 weeks after the surface water peak.
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  • 89
    Publication Date: 2018-03-22
    Description: Altimetric data from Geosat and some critical hydrographic measurements were used to estimate in real time the mesoscale physical oceanographic environment surrounding the Joint Global Ocean Flux Study (JGOFS) 1989 North Atlantic Bloom Experiment. Three cyclonic eddies, including an exceptionally large one, evolved and interacted over the 10 weeks of observations. Subsequent analysis of all available hydrographic data confirmed the real time estimates and provided further quantitative information concerning the mesoscale and submesoscale structure of the upper ocean. Remotely sensed indicators of near-surface chlorophyll content reveal significant biological variability on these wavelengths. The altimetric and hydrographic data have been assimilated into a dynamical model to produce optimal estimates of physical fields of interest as they evolve in time for use in physical and biological process studies
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  • 90
    Publication Date: 2018-03-22
    Description: The influence of increasing amounts of surfactants on the toxicity of hydrocarbons was determined using the bioluminescence inhibition test (Microtox test). Three biogenic and three synthetic surfactants were tested against the water-soluble fractions (WSF) of crude and weathered Ekofisk oil, phenol, and naphthalene. Surfactant concentrations below 100 mg litre−1 lowered the toxicity of the WSF, indicating an antagonistic interaction reducing the toxicities of surfactants and hydrocarbons. At concentrations greater than 100 mg litre−1 the toxicity rose again and was higher than the untreated WSF. The point of reversal seemed to be the critical micelle concentration, at which the formation of oil/water emulsions is possible.
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  • 91
    Publication Date: 2017-03-30
    Description: Biological and fishery features of the waves of abundance of Illex argentinus in three fishery regions −52°S (shelf with 180–230 m depths in exclusive economic zone of Argentina—EEZA), 46° and 42°S (continental slope with 600–800 m depths off the EEZA) in April–June 1990 were studied. According to age analysis of 629 statoliths made aboard, age-length structure of each wave of abundance were determined. In April–June active spawning migrations of I. argentinus were observed from feeding grounds located in limits 50–52°S along the continental slope northwards through 46° and 42° fishery regions. Only winter-hatched squids (hatched from June to September of the previous year) took part in migrations which were observed as waves of abundance in all three regions. Each migratory wave of abundance consisted of 2–4 successive monthly generations. The start of spawning movement was corresponded with the age and maturity state of the squid. Squid of all monthly generations began migrating from the 52°S region at a mean age of approximately 250 days, passed through 46°S at mean age 280 days and through 42°S at mean age 295 days. Males migrated 2–3 weeks earlier than females of the same generation. Rates of somatic growth were very low during migrations from 52° to 46°S (RDGR - 0.13% mantle length (ML) in mature males and 0.2% ML in maturing females). During movement from 46° to 42°S and, obviously further, mature squids practically ceased somatic growth. Estimated rate of migrations was 23.2–28.9 km day−1 (including current velocity), or 26–30 cm s−1 (0.47 body length s−1). Spawning was considered to occur on the continental slope of Uruguay and Brazil north of 35°S in July–August. Methodical approaches of efficient determination of squid age, growth and stock structure by means of investigation of squid biological features and statolith microstructure in each distinguished wave of abundance were elaborated.
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  • 92
    Publication Date: 2017-05-04
    Description: The effects of feeding a prepared surimi diet (fish-based) and a prepared pelleted diet (shrimpbased) on the survival, growth and feeding rate of the cuttlefish Sepia officinalis L. were evaluated during a 45-day experiment. One hundred and twenty juveniles of laboratory cultured cuttlefish (74.5 ± 12.36 g) were divided into three treatments and were fed thawed shrimp (control), pellets or surimi. Survival rates on these diets were 95.0%, 67.5% and 22.5%, respectively. Preliminary data indicated that the low survival of cuttlefish fed surimi may have been caused by low levels of copper in their blood (131 vs 244 μg/ml) since copper is required for their respiratory blood pigment, hemocyanin. Instantaneous growth rates were 2.71 % body weight BW/day for cuttlefish fed raw shrimp, 0.33% BW/day for cuttlefish fed pellets, and 0.54% BW/day for cuttlefish fed surimi. The feeding rate of cuttlefish fed shrimp was high (6–8% BW/day). The feeding rate on pellets increased with time (from 〈 1 to 3% BW/day) but never reached the level for raw shrimp. The feeding rate on surimi increased to equal the rate for raw shrimp during days 1–30 (8 to 9% BW/day) and thereafter decreased (〈4% BW/day). In conclusion, there was a major distinction between the palatability of a prepared diet and the ability of that diet to support growth. Surimi was highly palatable but resulted in poor survival, suggesting low nutritional quality. In contrast, pellets were less palatable but produced maintenance growth. Development of practical surimi diets will require supplementation of the surimi with soluble micro- and macronutrients.
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  • 93
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    Elsevier
    In:  Acta Oecologica - International Journal of Ecology, 14 (3). pp. 463-470.
    Publication Date: 2020-04-23
    Description: Changes in marine ecosystems can be manifested in many different ways, on different temporal and spatial scales. Seabirds are top consumers in marine foodwebs and offer opportunities to detect and assess the biological effects of changes in physical parameters (sea-surface temperature [SST], salinity, depth of thermocline etc.) of the marine ecosystem. We compare six-eight years' of data on the biology (diet, and breeding success) of four species of seabird (arctic tern Sterna paradisaea and common tern S. hirundo, which feed at the sea surface; and Atlantic puffin Fratercula antica and razorbill Alca torda, which dive 30-60 m for their prey) breeding on Machias Seal Island (MSI) in the Bay of Fundy with both our own meteorological and oceanographic measurements, and with standard measurements from conventional sources. These are compared with fisheries data on changes in the main prey of all the seabirds concerned (juvenile or '0-group' herring Clupea harengus) which are the most direct link between the seabirds and the physical properties of the marine system. We explore relationships between seabird productivity and diet, and other aspects of both herring biology (larval surveys, and fat content) and oceanography (SST data from the island, and remotely sensed data from the entrance to the Bay of Fundy). Timing of laying by puffins followed SST variation at neither the local (MSI) nor regional scales, but at the scale of the North Atlantic, following the trend of populations breeding off northern Norway. The proportion of herring in the diet of terns over 6 years varied inversely with herring larval abundance the previous fall; this relationship was not statistically significant in the puffin and razorbill. A major new finding is the considerable (approximately 50%) inter-annual variation in the energy density (fat content) of juvenile herring that are the main seabird prey; breeding success of both species of tern varied in parallel with the energy density of juvenile herring in the diet until the last two years of the study, when sandlance (Ammodytes sp.) and euphausid shrimp predominated in the diet. Our long-term research approach combines traditional population monitoring (of numbers of breeding birds) with demographic, behavioural and environmental monitoring, to provide new understanding of the marine ecosystem as well as of seabirds.
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  • 94
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    Springer
    In:  In: Applied Micropalaeontology. , ed. by Jenkins, D. G. Springer, Dordrecht, pp. 69-91.
    Publication Date: 2017-08-03
    Description: This chapter records the benthonic foraminifera associated with a biogenic gas seep in the North Sea. A sample from an actively seeping site contains a benthonic foraminiferal assemblage statistically distinct from that of a control site. The distinctions are in terms of, firstly, abundance, diversity and dominance, secondly, taxonomic composition, and thirdly, proportions of epifaunal (surface-dwelling) and infaunal (sediment-dwelling) morphotypes.
    Type: Book chapter , NonPeerReviewed
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  • 95
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    Unknown
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 40 (1-2). pp. 495-519.
    Publication Date: 2018-03-05
    Description: Productivity regime and phytoplankton size structure are described for two different epipelagic systems in the tropical/subtropical Northeast Atlantic Ocean investigated during 9–11 day drift studies in spring 1989 in the JGOFS North Atlantic Bloom Experiment, 18°N, 30°W and 33°N, 20°W. At the 18°N study site, an oligotrophic system was encountered. The water column above the main pycnocline at about 50–60 m depth was nutrient-depleted, and both chlorophyll and primary production displayed subsurface maxima at the nutricline. Picoplankton was the dominant size fraction, accounting for 78–90% of chlorophyll and 83–98% of primary production. Synechococcus-type coccoid cyanobacteria were the dominant picoplankters. The hydrographic situation was characterized by high small-scale variability; the most interesting feature was the intrusion of nutrient-depleted Subtropical Salinity Maximum Water into the euphotic zone, whose impacts on the productivity regime are discussed. At 33°N study site, a post-bloom situation was encountered. Although the euphotic zone was nutrient-depleted, higher amounts of larger phytoplankton were present, the contribution of picoplankton being 42–53% of chlorophyll and 42–86% of primary production. Over the course of the drift study, subsurface maxima of chlorophyll and productivity evolved, the contribution of picoplankton having increased. Picocyanobacteria again were the dominant picoplankters. At both study sites the profiles of abundance ratios of picocyanobacteria to picoeucaryotes cell numbers proved to be a useful tool to characterize water masses.
    Type: Article , PeerReviewed
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  • 96
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    Unknown
    Springer
    In:  Boundary-Layer Meteorology, 65 (3). pp. 249-254.
    Publication Date: 2018-03-07
    Description: Turbulence in the Planetary Boundary Layer has been a topic of research for a long time. Its theory, however, is hampered by the fact that we have fewer fundamental equations than unknowns when dealing with turbulent motions. The search for additional “laws” to match the number of equations with the number of unknowns in turbulence theory is commonly labelled the turbulent closure problem. Despite considerable effort, this problem has not been solved. There is a variety of approaches available. However, these have not converged towards a commonly accepted PBL theory, like the Monin-Obukhov similarity for the surface layer. The Working Group on Boundary Layer Dynamics and Air-Sea interaction of ICDM/IAMAP therefore invites the scientific community to discuss these problems and possible solutions. The present paper intends to stimulate such a discussion.
    Type: Article , PeerReviewed
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  • 97
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    Unknown
    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 40 (11-12). pp. 2167-2177.
    Publication Date: 2018-03-07
    Description: The origin and the spreading of the shallow Mediterranean water core (Ms) in the Iberian basin is discussed with a quasi-synoptic hydrographic data set enhanced by chlorofluoromethane (CFM) measurements. Its characteristic density level is found to be σt = 27.4. Characterized by high temperature and CFM values, Ms enters the Iberian basin in the region of Cape St Vincent between depths of 500–750 dbar. A heat anomaly of 〉11.8 × 109 J m−2 is chosen as the boundary between the presence of Ms and the background field. The core is found in a tongue-like shape as well as in separate isolated eddies of both cyclonic and anticyclonic circulation. Using the optimum multiparameter analysis (Tomczak and Large, 1989, Journal of Geophysical Research, 94, 16141–16149), the North Atlantic Central Water (NACW), which mixes with the Mediterranean outflow to form Ms, turned out to be in the mean 1°C warmer and 0.11 saltier than in regions with minor Mediterranean influence. This points to the Gulf of Cadiz as the origin of Ms, where the Mediterranean oufflows is in contact with NACW of the appropriate characteristics.
    Type: Article , PeerReviewed
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  • 98
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    Unknown
    Elsevier
    In:  Journal of Marine Systems, 4 (2-3). pp. 231-233.
    Publication Date: 2018-03-07
    Type: Article , PeerReviewed
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  • 99
    Publication Date: 2018-03-07
    Description: Gas chromatography-mass spectrometry (GC-MS) analyses of organic concentrates from eastern Mediterranean surface water show that dissolved fossil fuel residues are dominated by unsubstituted aromatic hydrocarbons and heterocyclic aromatics and thus resemble products of incomplete combustion. Deviating from this interpretation, preferential photochemical oxidation of alkyl-substituted aromatics is suggested as the principal causative mechanism, although, especially near land-based sources. the influence of combustion-derived unsubstituted aromatics is not defined. Total concentrations of dissolved aromatics as determined by GC-FID (flame ionization detection) and GC-MS from a limited data subset were in reasonable agreement with UV fluorescence measurements of dissolved/dispersed oil residues. The same preponderance of unsubstituted aromatics over their alkyl derivatives was found in extracts of the particulate phase, but concentrations were small relative to alkanes and/or alkenes of recent marine biosynthetic origin. CPI (carbon preference index) values of higher molecular weight n-alkanes indicated varying contributions of plant waxes to the particulate hydrocarbon pool. CPI values of corresponding dissolved n-alkanes were found to be near unity, indicating fossil fuel origin. Despite differences in higher molecular weight n-alkane CPI values and the predominance of recent biosynthetic aliphatics, the similarity of dissolved and particulate aromatic fractions suggests limited adsorption by particles of fossil fuel derived hydrocarbons and heterocyclics.
    Type: Article , PeerReviewed
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  • 100
    Publication Date: 2018-03-07
    Description: Saudi Arabian coastal waters near sandy beaches, severely contaminated with crude oil released in Kuwait during the 1991 Gulf War, as well as underlying sediments and a few bivalves, were analysed to assess concentrations and composition of petrogenic hydrocarbon mixtures and structurally related oxidation products. Concentrations of dissolved oil residues determined by UV spectrofluorometry (UVF) near oil deposits on beaches did not exceed 3.5 μg l−1; concentrations dropped to approximately 1/10th of this value a few miles offshore. Gravimetric concentrations of unfractionated lipophilic material extracted from large volumes of seawater at the same stations were up to 10 times those determined by UVF. After chromatography on silica gel, individual petroleum hydrocarbons in the low polarity fractions and oxidation products in the polar fractions were characterized by their spectra (GC/MS) and quantitated by Selected Ion Monitoring (SIM) GC/MS. Concentrations of oxidation products (ketones, aldehydes, alcohols) of aromatic hydrocarbons exceeded those of their parent compounds by more than an order of magnitude. Significant concentrations were also found of the presumably pyrogenic triplett sensitizer anthraquinone. Contributions to polar fractions of water extracts by biosynthesized lipids were negligible. UVF determinations appear to underestimate concentrations of dissolved oil residues, because many oxidation products have lower fluorescence quantum yields than the respective parent hydrocarbons. Their ecotoxicological properties are unknown. Concentrations measured in sediments by UVF ranged from 13 to 540 μg g−1 dry wt and 0.5 to 103 μg g−1 as measured by gas chromatography with flame ionization detection (FID GC). Bivalves ranged from 0.8 to 1.5 μg mg−1 extractable organic matter (EOM) by UVF, and 0.1 to 0.3 μg mg−1 EOM by GC analysis. PAHs were identified in sediment and bivalve extracts by GC/MS and quantitated by SIM GC/MS. None of the relatively water soluble alkylbenzene photo-oxidation products found in water samples nor any higher molecular weight quinones could be detected in sediment extracts. However, ion chromatograms strongly suggest the presence of numerous high molecular weight aromatics in that matrix.
    Type: Article , PeerReviewed
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