ALBERT

Description: Distribution and abundance of the horned octopus Eledone cirrhosa in the Tyrrhenian Sea are described on the basis of stratified-random bottom trawl surveys in spring and summer of the years 1985–1987. Specimens were caught between 25 and 630 m depth (higher densities between 50 and 200 m depth); mature males were found to prefer deeper bottoms than mature females. Young specimens occurred in spring samples from the Western Ligurian Sea and in summer samples from the Lower Tyrrhenian Sea, but were scarcely represented in the Higher Tyrrhenian Sea. Thus recruitment seems to be progressively delayed later in the season from north to south. The greatest abundance was recorded in the Higher Tyrrhenian Sea; wide seasonal variations of minimum stock biomass estimates have been observed and total biomass decreased from 1985 to 1987 in the surveyed areas.

Description: An investigation was carried out on the morphology, growth and microstructure of statoliths of 833 specimens of Sthenoteuthis pteropus (Steenstrup) mantle length (ML): 2–548 mm collected in the open waters of the Gulf of Guinea in 1984–1988. Statolith morphology is similar to that of other species of the subfamily Ommastrephinae and is similar to the sibling species S. oulaniensis. Statolith development includes five stages resembling those of Illex illecebrosus and other ommastrephids. Statolith growth is characterized by negative allometry. Increments visible in ground sections of statoliths can be grouped into four main growth zones, differing mainly in colour and increment width. Age and growth rates of S. pteropus were calculated using increment counts. The life span of females of all size groups does not exceed 1 yr, that of males is 1–2 months shorter, probably due to preliminary mating. Instantaneous relative growth rage (G) of paralarvae is high (up to 16% of body weight (BW)). G values for juveniles decline, but remain relatively high (7–8% BW). Juveniles attain 100–110 mm ML by age 100–110 days. G values for adults are the lowest (1.8–2% BW), but daily growth rates reach maximum values (40–70 g per day in large females of 450–500 mm ML). Each ontogenetic phase of S. pteropus corresponds to features of morphology, growth and microstructure of the statolith.

Description: The presented data on indirect and direct calorimetry in Halicryptus spinulosus, a species with prominent ecological significance in parts of the Baltic Sea, provide a basis for a better understanding of the metabolic adaptation of these animals to low oxygen availability in their environment. Metabolic rates in H. spinulosus were measured respirometrically as oxygen consumption and calorimetrically as heat dissipation. Oxygen uptake rates are in the range of M O2 = 3.81 ± 1.37 μmol O2·g−1 dry mass·h−1. Upon reimmersion into normoxic seawater after an anoxic incubation of 7 days, the animals exhibit an overshoot of oxygen consumption by a factor of 2.4. It takes at least 2 days for the animals to balance their oxygen consumption to previously measured rates. Direct calorimetry exhibits different strategies of H. spinulosus to cope with declining oxygen and anoxia. During the first 2 transitional days to anoxia in the calorimeter, the animals decreased heat dissipation moderately down to 53.4 and 26%, respectively, of aerobic values. The animals are not necessarily quiescent at the beginning of anoxia, but at the end of the experiments after 14 days metabolic rates have dropped substantially down to ≈2% of normoxic values. These findings are discussed with regard to an effective adaption to frequently changing oxygen regimes in deeper parts of the Baltic Sea.

Description: CO2 partial pressure in surface water was measured in the Northeast Atlantic and in the Hebride Shelf/North Sea area during a cruise with R.V. Poseidon in June 1991. A mean pCO2 of 303 μatm was found in the Atlantic between 50°N and 60°N. For an atmospheric CO2 content of 357.5 ppm(v) this corresponds to a partial pressure difference of −55 μatm. This supports the view that the subarctic Atlantic is a significant sink within the CO2 cycle between the ocean and the atmosphere. A comparison of our measurements with other data reveals that the pCO2 distribution changes significantly during May/June. This explained by seasonal warming, CO2 exchange with the atmosphere and biomass production. The contribution by each of these processes to the seasonal variations is calculated. It was found that during a plankton bloom the production of biomass is the dominating factor and may lower seawater pCO2 by almost 100 μatm. The shelf areas are charactrized by strong pCO2 gradients which are explained by water exchange with the Atlantic, temperature effects and biomass production.

Description: Sixteen samples (588 individuals) of the Argentine shortfin squid Illex argentinus were collected by commercial vessels from Falkland and surrounding waters (42°06–51°17S) between February and May 1990 and subjected to starch gel electrophoresis. Levels of electrophoretically detectable generic variability and the extent of population differentiation were determined from allele frequencies at 25 enzyme-coding loci. Low levels of genetic variability were detected, with the overall proportion of polymorphic loci, P = 0.28, mean heterozygosities per locus, H1 = 0.011, and the average effective number of alleles, Nc = 1.23. Marked population differentiation was indicated by significant differences in allele frequency among samples, and unbalanced genotypic distributions with heterozygote deficits at most loci. Nei's mean genetic distances (D) and identities (I) ranged from 0.000 to 0.130 and 1.000 to 0.878, respectively, underlining the marked genetic divergence detected. Some evidence of microgeographic differentiation (between replicates within sites) was observed. Individuals collected from northerly limits of the sampled area (42: 06 S, 58:09 W) were most genetically distinct (I = 0.878−0.904), suggesting the existence of a hitherto unrecognised subspecies or species of Illex. Emphasis is placed on the need to delimit putative stock boundaries, and develop appropriate population models to ensure conservation of genetic resources.

Description: Coccolith and dinoflagellate cyst assemblages have been investigated in five sediment cores from the Norwegian Sea and Fram Strait. Both fossil groups are characterized by similar patterns of composition. The assemblages contain high proportions of single species. The coccolith flora is of low diversity and consists almost entirely of Coccolithus pelagicus and Emiliania huxleyi. The dinoflagellate cysts are generally dominated by Operculodinium centrocarpum and Nematosphaeropsis labyrinthus. Other species, especially Bitectatodinium tepikiense, Peridinium faeroense and Impagidinium pallidum, sometimes contribute considerably to the assemblages. Based on the abundance of the assemblages and the ratio change between the dominating species it has been possible to establish three intervals of distinct major changes in surface water mass conditions. Sparse occurrences of coccoliths and dinoflagellate cysts have been observed before 10,000 yrs. B.P., indicating harsh environmental conditions with a distinct influence of meltwater and temporarily very slight inflow of Atlantic water. The modern surface-water circulation pattern was reinitiated during Termination IB. The assemblages suggest slightly cooler and probably less saline surface water conditions than are present today until 7500 yrs B.P. Solar insolation may have caused a first temperature peak which is responsible for the early Holocene productivity maximum. A considerable change in the composition of dinocyst and coccolith assemblages occurs corresponding approximately to the onset of the Holocene climatic optimum. This change was most probably linked to an almost synchronous reorganization of the hydrographic properties in the entire North Atlantic realm after the ice sheets had vanished. Since 6000 yrs B.P. the Norwegian Current with its modern oceanographic and ecological properties has been fully established.

Description: The alimentary tracts of 12 species of Antarctic squid were examined visually and serologically for the presence of Euphausia superba. Only four species, Alluroteuthis antarcticus, Galiteuthis glacialis, Martialia hyadesi and Psychroteuthis glacialis, contained material which was identifiable to species visually. Myctophid fish and euphausiids were the most common prey item. Serology showed that specimens of six species had eaten euphausiids. Where antisera showed cross-reactions with other potential prey species, biogeographical and haul data was used to determine the species of Euphausia consumed. P. glacialis (n=19) had consumed E. superba. Mastigoteuthis psychrophila (n=10) had eaten E. superba and/or E. triacantha. Brachioteuthis picta (n=6), M. hyadesi (n=27), and two Moroteuthis spp. (n=2) had consumed unidentified euphausiids. Bathyteuthis abyssicola (n=13) and Histioteuthis eltaninae (n=13) had not preyed on euphausiids. B. picta appeared to have fed in the net.

Description: Analysis of growth by year of hatching was estimated from the statolith growth increments of the oceanic squid Todarodes angolensis in three consecutive years. Samples were taken between November 1987 and February 1990 in the northern Benguela upwelling system. Growth increments suggested that hatching took place throughout the year and that the life cycle was ≈ 1 yr. From the onset of sexual maturity in the final third of the life cycle, growth rates were subject to considerable individual variation. Growth rate was significant highest in the 1987 year class, presumably because of exceptionally cool environmental conditions in the Benguela region. The response of T. angolensis to interannual environmental variability in the northern Benguela system is discussed. The results from this study suggest that it will be important to consider variability in growth rate in relation to environmental conditions, in future studies of squid age and growth.

Description: A central tenet of Antarctic ecology suggests that increases in Chinstrap Penguin (Pygoscelis antarctica) populations during the last four decades resulted from an increase in prey availability brought on by the decrease in baleen whale stocks. We question this tenet and present evidence to support the hypothesis that these increases are due to a gradual decrease in the frequency of cold years with extensive winter sea ice cover resulting from environmental warming. Supporting data were derived from one of the first, major multidisciplinary winter expedition to the Scotia and Weddell seas; recent satellite images of ocean ice cover; and the analysis of long-term surface temperature records and penguin demography. Our observations indicate there is a need to pay close attention to environmental data in the management of Southern Ocean resources given the complexity of relating biological changes to ecological perturbations.

Description: The seabird and seal community at Heard Island and the McDonald Islands comprised an estimated total biomass of 27893 tonnes of which the 15 breeding species of seabirds made up 70%. The total annual consumption of marine resources was estimated to be approximately 521 000 t, of which 81% was consumed by seabirds Approximately 165 000 t of fish, 41 600 t of squid and 312 000 t of crustaceans are consumed annually by this seabird and seal community. The annual energy flux to this community was estimated to be 2.17·1012 kJ and approximately 56 000 t of carbon are consumed annually. Breeding populations of King Penguins and Antarctic Fur Seals are increasing, that of the Southern Elephant Seal is decreasing; there are no data on the population trend for Macaroni Penguins, the predominant consumer species. Commercial fisheries are presently operating at the nearby Iles Kerguelen, and similar activities may prove to be commercially viable at Heard Island. The fishery is for Champsocephalus gunnari, a major prey species of penguins and Antarctic Fur Seals at Heard Island during the summer breeding season.

Description: Oil released into the sea undergoes immediate compositional changes as a result of processes of volatilization, dissolution, particle adsorption, and microbial and photochemical decomposition. Based on our observation of the molecular composition of oil residues dissolved in subtropical ocean waters, we hypothesized photo-oxidation of alkyl-substituted polycyclic aromatic hydrocarbons (PAH) and heterocyclic aromatics in preference to their unsubstituted parent compounds. As the ratios of alkyl to parent PAH are used to assign sources to contaminant residues in environmental samples, we tested the hypothesis in a controlled experiment: membrane-filtered seawater collected near the island of Bermuda was saturated with a Nigerian crude oil and exposed to natural sunlight in a quartz flask. Comparison with a dark control under otherwise identical conditions served to differentiate between sunlight-induced and microbially mediated decreases in concentration and changes in composition. We conclude on the basis of UV fluorescence, GC-MS, and microbiological data that sunlight-induced oxidation is responsible for the rapid loss of the UV fluorescence signal for total aromatic hydrocarbons and for the preferential depletion of the alkyl-substituted PAH and heterocyclic aromatics. Structure-dependent selectivity in the photo-oxidation of dissolved oil residues may thus result in residual hydrocarbon blends which could be mistaken as originating from incomplete combustion processes.

Description: The Neogene Bolboforma zones established in the North Atlantic have been correlated with the calcareous nannoplankton stratigraphy obtained by investigation of the same samples from DSDP Sites 12–116 (44 samples), 49–408 (76 samples), 81–555 (43 samples) and 94–608 (103 samples). The absolute ages for the zonal boundaries were determined by the paleomagmetic record of Site 94–608. This correlation and the age determinations are additional useful tools to develop a precise biostratigraphy of Neogene sediments in the Northern Atlantic.

Description: Acoustic basement lies at an average of between 6.0 and 6.5 sec two-way time below sea level in the southern Rockall Trough and northern Porcupine Abyssal Plain. The overlying sedimentary succession reaches maximum thicknesses of at least 4.0 sec, and can be divided by 3 regionally-developed seismic reflecting horizons, which are used as a framework to establish an acoustic stratigraphy for the area by selecting three “type” seismic sections. These reflectors are named, in ascending order, Shackleton, Charcot and Challenger. The area is crossed by E—W basement high structures, the Clare Lineament (which may be an easterly extension of the Charlie Gibbs Fracture Zone), that separates the Porcupine Abyssal Plain from the eastern part of southern Rockall Trough. Under the latter, the post-Shackleton acoustic sequence is thickened, as if dammed to the north of the Clare Lineament, whilst a further thickening, above reflector Charcot, occurs along a NE—SW line somewhat farther north into the southern Rockall Trough. This can also be related to shallow-lying acoustic basement features. Pre-Shackleton sediments overlie a very irregular basement topography. The acoustic characters of the various sediment packages are described and it is speculated that major changes in the sedimentary environments took place across reflectors Shackleton and Challenger, the latter probably establishing the modern bottom current circulation patterns. No ages can be unequivocally assigned to the main reflectors, but previously published data suggest a late Eocene—Oligocene age for Challenger. Possible lavas or sills are identified in the succession between reflectors Shackleton and Charcot.

Description: Condensed pelagic deposits characterize the uppermost sediment sequence of the Maud Rise in the eastern Weddell Sea. The comparison of subbottom profiling data with the sediments drilled at two ODP sites shows that Lithologic Unit Ib deposited during late Miocene to late Pliocene times is generally characterized by acoustic transparency. A prominent reflector with strongly increased amplitude (called Reflector “Pc”) occurs within this mainly homogeneous diatom ooze unit and is correlated with the porcellanite horizon found at ODP Site 689. As evidenced by sediment findings, Reflector “Pc” marks a distinct stratigraphic layer of early Pliocene age. The development of the Reflector “Pc” and its amplitude of reflection in the echosounding records is most likely caused by the silica cementation of porcellanite within this layer. The analyses of the sediment echosounder profiles from five R.V. Polarstern cruises make it possible to map the regional distribution of Reflector “Pc”. In large areas of the central Maud Rise, a patchy but also continuous distribution of Reflector “Pc” was found. The reflector does not occur in sediments below 3000 meters of water. On average Reflector “Pc” is detected around 11 and 12 meters below seafloor, but depth occurrence is highly variable within the range of 8 m to more than 18 m. The apparent amplitude of Reflector “Pc” is higher in those areas where the diatom ooze Unit Ib reaches greater thicknesses, which may be caused by local enhanced tectonic subsidence. In general a good correlation of Reflector “Pc” amplitude and thickness of lithologic Unit Ib is observed. This may imply that the diatom ooze Unit Ib serves as a silica source, since the extent of silica cementation of the porcellanite layer is controlled by the amount of dissolved silica supply. Other possible interpretations for silica sources include silica-rich interstitial water ascending from deeper sediment levels using tectonic structures for migration.

Description: Dense Antarctic Bottom Water formed around the continent of Antarctica spreads northward in the Atlantic underneath North Atlantic Deep Water, gradually mixing and upwelling into it. This Antarctic Water forms a significant element of the meridional circulation in both directions: northward as bottom water and southward as deep water. It is important to determine the strength of each component to assess its role in ocean circulation. Such measurements are useful when made in constricted pathways because any flow is more clearly defined. A new set of fine-resolution hydrograhic measurements in the Hunter Channel of the South Atlantic Ocean has been obtained, which allow the geostrophic bottom flow there to be estimated for the first time. The northward flow through the Hunter Channel of water cooler than 2-degrees-C is thus estimated to be 0.7 X 10(6) m3 s-1.

Description: Nine gravity cores collected on the East Greenland continental margin off Kangerdlugssuaq Fjord reveal a drastic decrease in average sedimentation rates from the cross-shelf through the continental slope (from 43.2 cm/kyrs to 2.2 cm/kyrs, respectively). Since the last deglaciation, beginning at 〈15, 000 yrs B.P., both carbonate and non-carabonate accumulation rates have been controlled by the decrease in glaciers and sea ice and the increase in surface-water circulation. CaCo3 and non-CaCO3 accumulation rates at about 14,000 yrs B.P. were high on the outer shelf, followed by high values at the inner shelf about 9000 yrs B.P., suggestive or rapid glacier retreat. About 9000 yrs B.P., the northerly flowing Irminger Current and the southerly flowing East Greenland Current may have increased intensity leading to distinct increases in CaCO3 accumulation (〉2g/cm2kyrs). At 4000 yrs B.P., both CaCO3 and non-CaCO3 accumulation rates became high (〈g/cm2kyrs); since 3000 yrs B.P. these rates distinctly decreased. Melting of glaciers and current activity, which drastically changed in space and time controlled the terrigenous sediment input, and thus the grain-size distribution and the physical properties of sediments, across the shelf. These observations suggest that current winnowing on sediments is one of the dominant processes at present. This is seen in the acoustic reflectivity and in the acoustically hard seafloor, particularly at the upper continental slope. In addition, icebergs transported southward along the continental margin, have scoured the sediment surface in water depths 〈350m.

Description: The concentration of 230Th in Mn crust VA13-2 (146°W, 9°25′S, 4830 m) from the Pacific Ocean was measured with high depth resolution (0.02 mm) to a depth of 1.4 mm corresponding to an age of ∼226 ka B.P. The mean growth rate estimated from these results is 6.2 ± 0.4 mm/Ma. However, the exponential curve obtained shows two drastic events in the 230Th concentration record with durations of41 ± 4 ka and 37 ± 6 ka which are interpreted as growth standstills. The decay-corrected 230Th concentration is inversely correlated with those of Mn, Fe and Co indicating that the 230Th flux into the crust has been constant throughout time and that the observed fluctuations in 230Th are due to dilution by the main components. By applying a constant 230Th flux model, high-resolution growth rates were derived from every sample investigated. A detailed comparison of the growth pattern with the SPECMAP time table reveals that the VA13-2 growth rates tend to be higher during interglacial than during glacial periods. In particular, the observed growth standstills are associated with glacial stages 6 and 8. Further investigation of Mn crust 72 DK 9 taken from shallower water (170°35′W, 20°13′N, 1550 m) tend to confirm that there is a link between the growth rates of hydrogenetic crusts and the climate of the Late Quaternary.

Description: Two new phenylpropanoid glycosides, leonosides A and B, and two known glycosides lavandulifolioside and verbascoside, were isolated from the aerial parts ofLeonurus glaucescens. On the basis of chemical and spectral evidence, leonosides A and B were shown to be β-(3,4-dihydroxyphenyl)-ethyl-O-α-l-arabinopyranosyl-(1→2)-α-l-rhamnopyranosyl-(1→3)-4-O-feruloyl-β-d-glucopyranoside and β-(3-hydroxy, 4-methoxyphenyl)-ethyl-O-α-l-arabinopyranosyl-(1→2)-α-l-rhamnopyranosyl-(1→3)-4-O-feruloyl-β-d-glucopyranoside, respectively.

Description: Nitrous oxide (N2O) is an important atmospheric trace gas. Changes in the concentration of N2O in the atmosphere have evoked considerable interest because of its role in (i) regulating stratospheric ozone levels, and (ii) contributing to the atmospheric greenhouse phenomenon. The global concentration of N2O in the atmosphere has been rising since the start of the Industrial Revolution, before which the concentration was almost constant at about 280–290 ppbv. In ad 1990, it reached about 310 ppbv and is rising at a rate of 0·5–1·1 ppbv (i.e. 0·2–0·3%) per year. In this paper, the history of N2O in the Earth's atmosphere, together with its latitudinal and altitudinal distributions, and seasonal oscillations, are described.

Description: Teleseismic P-wave travel time residuals recorded by a mobile, shortperiod network are interpreted using the composition of crustal and upper mantle xenoliths. A three-dimensional inversion of the P residuals revealed a small-scale anomalous domain with a velocity reduction of 3% in the crust and a broad low-velocity anomaly of 4% beneath the Moho down to a depth of 50 km. Xenoliths of the Miocene Urach volcanic field (“UVF”, 1300 km2; 355 eruptive centres, mostly diatremes) comprise phlogopite-bearing, clinopyroxene-rich mantle xenoliths, evidence for large ion lithophile element (LIL) metasomatism in an originally depleted harzburgitic mantle, reflecting chemical modification of the upper mantle beneath the UVF. The metasomatism caused partial melting in the spinel peridotite stability field, indicated by glasses in xenoliths, and a diapiric uprise of the partially molten metasomatized mantle. The observed reduction of the P-wave velocity of 4% in the lithospheric mantle can be explained by a local enrichment of phlogopite accompanied by increased temperatures. The crustal low-velocity body coincides very well with the postulated volume of an ancient intracrustal magma chamber or system of chambers required by the composition of xenoliths, the magnetization of the diatremes and the spatial distribution of the volcanic eruption centres.

Description: Menaquinones (vitamin K2) were the only isoprenoid quinones found in the Actinomycetes tested. Thermomonospora strains belonging to the species T. alba, T. curvata and T. fusca contained very complex mixtures of menaquinones with nine, ten and eleven isoprene units. Hexa- and octahydrogenated menaquinones with ten isoprene units constituted the major components in T. alba, whereas, octahydrogenated menaquinones with ten isoprene units predominated in T. curvata and T. fusca. Substantial amounts of hitherto undescribed hexa-, octa-, and decahydrogenated menaquinones with eleven isoprene units were also present in the three species. The representative of the taxon Thermomonospora (Actinobifida) chromogena examined differed in possessing major amounts of tetrahydrogenated menaquinones with only nine isoprene units; a pattern also found in Saccharomonospora viridis, Actinomadura flexuosa and Micromonospora halophytica subsp. halophytica. The chemotaxonomic data and supporting results of numerical taxonomic studies suggest that Actinobifida chromogena may have been wrongly classified in the genus Thermomonospora.

Description: Middle Pleistocene strata of the Kidnappers Group consist of a conformable sequence of alternating fluvio-lacustrine and shallow marine sediments exposed along coastal cliffs near Cape Kidnappers, southern Hawkes Bay, New Zealand. Three major paleomagnetic polarity intervals are recognised and interpreted as Jaramillo Normal Subchron, upper Matuyama Reversed Chron and Brunhes Normal Chron. This and biostratigraphy indicates an age range of 0.97 to 0.54 Ma for the group, compared to 0.85 to 〈 0.33 Ma previously suggested by fission track ages of tuffs. The new age control and facies interpretations suggest that the upper part of the group represents oxygen isotope stages 22 to 15. The duration and magnitude of isotope stages is reflected in the relative thicknesses of lithological units. Glacial periods are recorded as alluvial aggradation in the form of braidplain conglomerates, while estuarine and subaerial sands and muds with temperate climate pollens represent interglacial periods. This contrasts with many coastal and shelf sequences where glacial periods are represented by unconformities. Chemical and paleomagnetic characterisation of silicic tuffs in the Kidnappers Group establishes correlation to other sections and cores in New Zealand, the Tasman Sea and the western Pacific Ocean, thus providing temporal correlation for a range of sedimentary environments.