ALBERT

Description: A new image of the French continental crust between Brabant (Belgium) and the Basque province of Spain is presented on the basis of considerable recent geological and geophysical information as well as the compilation and reInterprétation of previously available data. The resulting section, which shows the main basement structures to a depth of 45 km, also is the first nonspeculative image of the westernmost part of the Variscan orogen. The French Global Geoscience Transect reveals a complete picture of this orogen between its remnant root and the surface. The divergent thrusts are bounded on the north and in the south by the old Brabant and Ebro-Aquitaine cratons, respectively; these thrusts also involve two previous plate boundaries. The lower part of the orogen is limited by a layered lower crust, probably of Permian age. Near the surface the Hercynian orogen is buried—near the northern end of the transect by the Paris Basin, which can be considered an eastward extension of the English Channel, and in the south by the South Armorican continental margin, which makes a transition between the oceanic crust of the Bay of Biscay and the axis of the Variscan orogen. In this area, the deep Parentis graben is located at the site of pronounced crustal thinning, since only 7 km of Hercynian crust are now preserved.

Description: The assessment of direct effects of anthropogenic CO2 increase on the marine biota has received relatively little attention compared to the intense research on CO2-related responses of the terrestrial biosphere. Yet, due to the rapid air–sea gas exchange, the observed past and predicted future rise in atmospheric CO2 causes a corresponding increase in seawater CO2 concentrations, [CO2], in upper ocean waters. Increasing [CO2] leads to considerable changes in the surface ocean carbonate system, resulting in decreases in pH and the carbonate concentration, [CO2−3]. These changes can be shown to have strong impacts on the marine biota. Here we will distinguish between CO2-related responses of the marine biota which (a) potentially affect the ocean's biological carbon pumps and (b) are relevant to the interpretation of diagnostic tools (proxies) used to assess climate change on geological times scales. With regard to the former, three direct effects of increasing [CO2] on marine plankton have been recognized: enhanced phytoplankton growth rate, changing elemental composition of primary produced organic matter, and reduced biogenic calcification. Although quantitative estimates of their impacts on the oceanic carbon cycle are not yet feasible, all three effects increase the ocean's capacity to take up and store atmospheric CO2 and hence, can serve as negative feedbacks to anthropogenic CO2 increase. With respect to proxies used in palaeo-reconstructions, CO2-sensitivity is found in carbon isotope fractionation by phytoplankton and foraminifera. While CO2- dependent isotope fractionation by phytoplankton may be of potential use in reconstructing surface ocean pCO2 at ancient times, CO2-related effects on the isotopic composition of foraminiferal shells confounds the use of the difference in isotopic signals between planktonic and benthic shells as a measure for the strength of marine primary production. The latter effect also offers an alternative explanation for the large negative swings in δ13C of foraminiferal calcite between glacial and interglacial periods. Changes in [CO2−3] affect the δ18O in foraminiferal shells. Taking this into account brings sea surface temperature estimates for the glacial tropics closer to those obtained from other geochemical proxies.

Description: Exposure of Fucus spiralis germlings to precise copper concentrations (0 to 844 nM Cu2+) in chemically defined medium demonstrated a relationship between urltrastructural changes and growth retardation with increasing copper concentration. Electron-translucent vesicles, present in ova, which normally disappear after fertilization, accumulated in germlings exposed to Cu2+ above 10.6 nM, suggesting that copper may inhibit a metabolic pathway involved in cell wall formation which is initiated by fertilization No membrane damage was observed during the exposure period. During a post-exposure period in copper-free medium, recovery occurred (rhizoid extension, apical hair formation) in germlings previously exposed to concentrations below 106 nM Cu2+ and electron-translucent vesicles became granular and disappeared. It is proposed that the electron-translucent vesicles contain a cell wall precursor and that copper inhibits its incorporation into the cell wall, preventing growth and development of the zygote.

Description: The global sediment mass-age distribution indicates large variations in the rates of carbonate sedimentation through time. The largest mass of carbonate deposited during the entire history of the earth was produced during the Cambrian, possibly following on an episode of phosphogenesis in the Late Precambrian. A second major episode occurred during the Late Devonian, probably reflecting the invasion of land by plants that altered the rock-weathering and soil-forming regimes. Other lesser pulses of carbonate deposition occurred in the Late Permian, Triassic, and Cretaceous. A shift in the locus of carbonate deposition from shallow waters to the deep sea occurred during the Cretaceous.

Description: The “rugophilic”; behaviour (e.g. the preference for settling in concavities) of barnacles is well documented. In contrast, little is known about settlement preferences of other species with regard to surface microtopography. In a randomized block design, five different rugosities (smooth, 0.1 mm, 0.5 mm, 1 mm, 5 mm) were exposed to natural fouling in the Baltic Sea. In four experiments, test panels were colonized by Mytilus edulis, Polydora dliata, Balanus improvisus, diatoms, hydrozoa, bryozoa, and several ciliates. Settlement densities and microtopographical preferences for pits or elevations as a function of grain size were evaluated. Rugosities influenced settlement densities and the microtopographical preferences of almost all investigated species. Settlement densities were generally lowest on smooth panels, with most species showing distinct preferences for different rugosities. While a preference for pits was frequent, in some species the proportion of individuals settling on elevations significantly increased with roughness. These data on microtopographical preferences of different species give new insights into interactions between settlement behaviour, surface roughness, boundary layer hydrodynamics and community structure.

Description: A quantitative relationship between observed sea-ice roughness and simulated large-scale deformation work is established in order to provide new means for model validation and a better representation of the sea-ice component in climate modelling. Sea-ice roughness is introduced as an additional prognostic variable in a dynamic–thermodynamic sea-ice model with a viscous-plastic rheology. It is defined as the accumulated work of internal forces acting upon an ice volume, given in energy per area. A fraction of this total deformation work is transferred to the potential energy stored in pressure ridges. Using ridge geometries and distribution functions from observations, observable quantities like mean pressure ridge height, ridge frequency as well as volumetric and areal fractions of deformed ice are derived from the simulated ice roughness. Comparisons of these simulated quantities with measurements (submarine-borne sonars, laser altimeters on helicopters) show good agreement. Satellite-borne observations of sea-ice roughness now under development will provide an even larger data set which will be used for model verification. Additionally roughness-dependent drag coefficients are introduced to account for the effect on the momentum exchange between ocean and atmosphere due to the form drag of roughness elements. The simulations indicate that the inclusion of sea-ice roughness provides for a more realistic representation of the boundary layer processes in climate models.

Description: To study the variability of the thermohaline circulation in the North Atlantic on decadal time scales, the atmospheric regional model REMO is currently investigated as a component of a fully-coupled atmosphere–ice–ocean model for the Arctic/North Atlantic. A comparison of a 5-year uncoupled simulation of the regional model with a 5-year NCEP/NCAR reanalysis period is carried out in order to assess the performance of the regional model in polar and subpolar regions. The model simulates basic structures realistically. It performs well in middle latitudes but shows some problems in the region of the marginal ice zone and in continental regions with extreme temperature amplitudes. The high elevations of Greenland in the central part of the model domain give rise to problems in the model dynamics, resulting in moderate deviations from NCEP/NCAR reanalysis.

Description: At Aqaba in the Northern Gulf of Aqaba, Red Sea, the stable oxygen isotope record of a Por#es lutea coral colony was studied. From a vertical and a horizontal core two parts from the base of the colony (10 years of coral growth), and two parts from the living surface (12 years of coral growth) were analysed with a monthly sampling resolution. The results show that seasonality of sea surface temperatures (SST) in the northem GulfofAqaba has increased since the early 19th century, mainly due to higher summer temper- atures. 8~80-ratios indicate that SST increased by at least 1.3~ Horizontal and vertical cores display dif- ferent variations in the modern parts, probably caused by the very shallow water depth of the youngest part of the vertical core.

Description: Repeatable species dominance patterns across nutrient ratio gradients are found both in culture competition experiments and in natural waters. However, the mechanisms behind these similar patterns need not to be identical. In chemostat experiments, such patterns are caused by the two-way competitive interactions between contemporaneously occurring organisms. Nutrient competition may be important in situ too, but there is an additional effect of early successional species influencing the nutrient environment for later successional species, without being influenced themselves by their successors.

Description: Application of a neural network to ERS-SAR images to retrieve pressure ridge spatial frequencies is presented. For an independent dataset, the rmserror between the retrieved and the true ridge frequency as determined by means of laser profiling was about 5 ridges per kilometre, or 30%. The network is trained with results from in situ laser profiling of ridge distributions and coincident SAR backscatter properties. The study focuses on summer data from the Bellingshausen, Amundsen and Weddell Seas in Antarctica, which were gathered in February 1994 and 1997. Pressure ridge frequencies varied from 3 to 30 ridges per kilometre between different regions, thus providing a wide range of training and test data for the algorithm development. From ERS-SAR images covering the area of the laser flights with a time difference of a few days at maximum, histograms of the backscatter coefficient sigma0 were extracted. Statistical parameters (e.g. mean, standard deviation, tail-to-mean ratio) were calculated from these distributions and compared with the results of the laser flights. Generally, the mean backscatter increases with a growing ridge frequency, and the signal range becomes narrower. However, these correlations are only poor, and improved results are obtained when the statistical parameters are combined to train the neural network.

Description: It is well documented that animals take risk of predation into account when making decisions about how to behave in particular situations, often trading-off risk against opportunities for mating or acquiring energy. Such an ability implies that animals have reliable information about the risk of predation at a given place and time. Chemosensory cues are an important source of such information. They reliably reveal the presence of predators (or their presence in the immediate past) and may also provide information on predator activity level and diet. In certain circumstances (e.g., in the dark, for animals in hiding) they may be the only cues available. Although a vast literature exists on the responses of prey to predator chemosensory cues (or odours), these studies are widely scattered, from marine biology to biological control, and not well known or appreciated by behavioural ecologists. In this paper, we provide an exhaustive review of this literature, primarily in tabular form. We highlight some of the more representative examples in the text, and discuss some ecological and evolutionary aspects of the use of chemosensory information for prey decision making. Curiously, only one example illustrates the ability of birds to detect predator odours and we have found no examples for terrestrial insects, suggesting a fruitful area for future study.

Description: Cyanobacteria are important constituents of most aquatic ecosystems on earth, and planktonic forms frequently show mass development in lakes and estuaries. Despite extensive scientific efforts directed towards research on cyanobacteria, a comprehensive theory explaining their success is lacking. Because cyanobacteria comprise a diverse group of organisms, it is concluded that any analysis of the conditions leading to cyanobacterial dominance in pelagic ecosystems should consider at least three different subgroups, classified based on presence or absence of (i) buoyancy regulation and (ii) the ability to fix molecular nitrogen. In this review, nine single-factor hypotheses regarding regulation of cyanobacterial development are examined against the background of physiological and ecological characteristics of these organisms. Special emphasis has been put on understanding differences in nitrogen metabolism between cyanobacteria and algae which directly relate to a hypothesis conceming inorganic nitrogen forms and cyanobacterial success previously presented by our research group. The review lends support to the theory that cyanobacteria have a low competitive ability for nitrate compared with algae and a high ability to compete for ammonium, particularly under nitrogen-limiting conditions. Finally it is concluded that to understand cyanobacterial devlopment and how high Standing Stocks in pelagic ecosystems are maintained requires parts o f all the single-factor hypotheses initially presented.

Description: The capture of 52 specimens of the cirrate octopod Grimpoteuthis glacialis (Robson, 1930), of dorsal mantle length 20-165 mm during a 1996 trawling survey near the Antarctic Peninsula allowed the basic biology of the species to be examined. Their presence in bottom trawls at depths of 333-879 m, but their absence from benthopelagic and pelagic trawls, is consistent with a primarily benthic habitat. The largest single sample, 40 animals, came from a soft mud bottom and highlights the patchy nature of the distribution. Males tended to be bigger in total length and mass than females of similar mantle length. The males, however, were mature at a smaller size. Mature males have tiny sperm packets, rather than typical cephalopod spermatophores, in their distal reproductive tract. Mature females have large, smooth eggs in the proximal oviduct, in the huge oviducal gland and in the distal oviduct. Eggs in the distal oviduct have a thick, sticky coating that hardens in seawater into a secondary egg case. Ovarian eggs vary greatly in size, possibly indicating protracted egg laying. Observations on live animals indicate that the species swims primarily by fin action, rather than by jetting or medusoid pulses with the arm/web complex. It may be capable of limited changes in colour pattern, especially on the oral surface of the web. Three pairs of surface structures that appear superficially to be white spots anterior to the eyes and near the bases of the fins are actually transparent patches in the skin. When considered in association with the transparent subdermal layer and the anatomy of the eyes, optic nerves and optic lobes, these clear patches seem to function in detecting unfocused light on the horizontal plane of the benthic animal.

Description: The density of seawater is a complex function of temperature, salinity, and pressure. Because of the non-linearity of the equation of state of seawater, the densities of sea waters having the same temperature and the same salinity differences (with respect to the mean salinity of the ocean) will vary with the mean salinity of the ocean. Although this strange property of seawater is evident in a plot of the equation of state, it has never been considered in trying to reconstruct ancient ocean circulation. These differences in the density field may have caused the ocean to respond differently to atmospheric forcing in the past. The different response may hold the key to understanding "ocean anoxic events" and episodes of large-scale burial of organic carbon and production of petroleum source rocks.

Description: The Late Cretaceous was much warmer than today. There was no significant ice at high latitudes, meridional thermal gradients were low, and continental interiors remained warm during winter. Late Cretaceous atmospheric C02 concentrations were about four times greater than today and an enhanced "greenhouse" effect contributed to the overall warmth of the Late Cretaceous. However , increases in atmospheric C02 tend to increase temperatures at all latitudes and do not explain the very low thermal gradients recognized in the geologic record. Increased poleward ocean heat transport has been cited as a mechanism for maintaining low meridional thermal gradients during the Cretaceous. However , ocean heat transport values larger than the present day are difficult to reconcile. In addition, low meridional thermal gradients suggest sluggish atmospheric circulation, implying that the advection of heat from the warm oceans into the continental interiors was limited. In general, paleoclimate simulations using Atmospheric General Circulations Models (AGCMs) have not been successful in simulating the low meridional thermal gradients and warm winter continental interiors of the Cretaceous, forcing the concept of "equability" to be questioned. Until recently, the physical effects of vegetation on pre-Quaternary climates have largely been ignored. Terrestrial ecosystems influence global climate by affecting the exchange of energy, water, and momentum between the land surface and the atmosphere. In a new approach to pre-Quaternary paleoclimate modeling, Campanian (80 Ma) climate and vegetation have been simulated using a global climate model (GENESIS Version 2.0), coupled to a predictive vegetation model (EVE), resulting in a realistic simulation of Late Cretaceous climate. The predicted distribution of Late Cretaceous vegetation played an important role in the maintenance of low meridional thermal gradients, polar warmth, and equable continental interiors. High latitude forests reduced albedo, especially during snowcovered months, and increased net surface radiation and latent heat flux.

Description: Beaks of 133 specimens of Todarodes sagittatus caught in the central East Atlantic were studied. Relationships between several measurements of the upper and lower beaks and dorsal mantle length (DML) and total mass were calculated. The darkening process or pigmentation of both beaks was investigated and a qualitative scale of eight degrees of pigmentation developed. Except for the hood of the lower beak, the growth of both beaks was allometrically negative in relation to DML in males, whereas the growth of several parts of both beaks of females was allometrically positive. The hood grew faster than all other parts of the male beak and faster than all parts of the lower beak of females. Regression coefficients calculated for the growth of the beaks revealed differences between the growth patterns of females and males (p 〈 0.05). The results relating to darkening and the maturing process suggest that they are related and that they take place over a very short period in the life of the squid.

Description: A total of 206 specimens of the ommastrephid squid Todarodes sagittatus, obtained from three areas of the central eastern Atlantic (Canary Islands/African coast, Madeira, and the Gettysburg Bank area south of Portugal) were examined. New information on size, mass, length-mass relationships, reproductive biology, and diet of the squid from a hitherto not very well studied area is supplied. Females dominated the samples (78%) and attained larger size and mass than males. Dorsal mantle lengths of T. sagittatus in the Canary Islands/African coast samples and in the Madeira region were similar, 167 – 348 mm for females and 175 – 269 mm for males. From the Gettysburg Bank all specimens were immature, females ranging between 71 and 276 mm and males from 98 to 233 mm. Mature females were found mainly during winter and mature males nearly year-round, indicating that they mature earlier than females and at a smaller size. Prey consisted mainly offish (54.9%), decapods (18.8%) and cephalopods (12.1%). Otoliths and fish bones identified from stomach contents suggest that myctophids were the most common and diverse prey.

Description: Deep waters of the Sea of Japan and surface waters of the Pacific Coast of Honshu and the northeast Sea of Japan were analysed for polychlorinated biphenyls (PCBs) pollution. the ΣPCB concentrations in solution in the Sea of Japan (50–3000 m) were between 140 and 1230 fg dm−3. the space-integrated surface water concentration near the Pacific coast of northern Honshu was 140 fg dm−3and for the surface water of the Sea of Japan was 230 fg dm−3. Based on these analyses four water masses were deduced in the Sea of Japan during the summer months. It is shown for the first time in the Sea of Japan that polychlorinated biphenyls are excellent chemical indicators of not only the anthropogenic pollution, but also water masses.

Description: Epibiosis on four marine benthic invertebrate species was found to be reduced relative to other nearby surfaces, suggesting the existence of an underlying protection against fouling. In all four cases, toxic chemical antifouling defenses were wanting or inconsistent. However, the lack of epibionts could be attributed to the existence of non‐toxic protective properties in all instances, viz. periodic emergence and mutual grazing in the gastropod, Littorina littorea, cumulative filtration and an as yet unidentified fouling‐reducing property of the periostracum of the bivalve Mytilus edulis, repellency and, possibly, mucus secretion in the colonial ascidian, Cystodytes lobatus, burrowing, periodic emergence (intertidal individuals) and moulting in the crustacean, Carcinus maenas. It seems that such protective systems are often multiple, consisting of several, more or less overlapping, adaptations to reduce fouling. Characteristics of these non‐toxic, multiple protection systems and their significance for potential epibionts are discussed.

Description: Seasonal distribution, size composition, age structure and growth of Berryteuthis magister juveniles (mantle length from 20 to 130 mm) were studied in the western Bering Sea (from 1700E to 179°W) between June and October 1994. According to the analysis of 1030 statoliths, the juveniles hatched from December to June with a peak in February and March. Growth data for different seasonally hatched groups were best fitted by an exponential function, summer-hatched juveniles demonstrated the fastest growth. B. magister attained the length at which it recruits (130 mm mantle length) at an age ranging from 140 to 200 days. Comparison of variability of both juvenile age structures and geostrophic currents in the region revealed that the Eastern Bering Slope Current (EBSC) was the main carrier of B. magister juveniles from the spawning grounds to the western Bering Sea. Seasonal variability of the EBSC determined the differences in juvenile migratory patterns. During its intense stage in May-June, the EBSC transported winter-hatched and spring-hatched juveniles first to the eastern part of the region and then westward along the slope. During its relaxed stage in July-September, the EBSC carried spring- and summer-hatched juveniles across the deep-water part of the Aleutian Basin directly to the western part of the region.

Description: Cephalopod eggs and egg masses turn up in samples taken during oceanographic cruises (including subsamples consisting of the stomach contents of marine predators); they are encountered by Scuba divers and crews of manned submersibles, and stranded egg masses can be found on ocean beaches around the world. If it is comparatively easy to identify such material as "squid eggs", it is much more difficult to recognize the group or species to which the eggs belong. There are various reasons why the identification of eggs and egg masses is often difficult or impossible, especially for the non-specialist. The lack of standardized illustrated keys showing both the embryonic stages and the corresponding aspects of egg capsules for well known species is a major impediment to identification or further developments needed to optimize the chances of finding hitherto unknown material...

Description: The highly active squid which inhabit the pelagic zones of continental seas are characterized by high energy requirements and have been termed invertebrate athletes. In this paper, the physiological and biochemical background of muscular performance in squid from different environments is reviewed and the physiological and environmental factors limiting performance levels are addressed. One important factor is the highly concentrated haemocyanin which, in ommastrephid squid, and by virtue of their extreme pH dependence, helps to load oxygen efficiently in the gills and unload it fully into the tissues. Squid regulate their extracellular pH more efficiently than intracellular pH, so protecting the haemocyanin from fatal pH changes. However, a large proportion of the oxygen requirement in the mantle muscle must still be provided by oxygen uptake through the skin. Anaerobic mechanisms become involved beyond critical swimming speeds once oxygen supply to mitochondria becomes limiting. Onset of anaerobiosis also characterizes the limits of long-term tolerance to progressive hypoxia at a critical P O2 and to high, above-critical temperatures. In general, anaerobic energy production reflects an inability to meet oxygen demand and indicates transition to a time-limited situation. The development of energy-saving locomotion strategies therefore shifts critical thresholds and extends tolerance periods in species exposed to environmental extremes, typically in coastal areas. There, negatively buoyant squid make greater use of the fin for economical swimming, which is also advantageous because of the complexity of the environment. In Lolliguncula brevis, the rate at which anaerobic resources are used above the critical swimming velocity is minimized by oscillating between periods of high and low pressure jets, thereby extending the period during which the animal can dive into hypoxic or warm water. However, only jet propulsion can economically attain the high velocities necessary in the open sea. Accordingly, the highest performance levels are seen in squid inhabiting the open sea, and they are only made possible by the uniform environmental parameters. Some squid may be able to operate at their functional and environmental limits, revealing a trade-off between oxygen availability, temperature, performance level and, possibly, body size.

Description: A peculiar squid paralarva from Hawaiian waters was described by Young (1991, Bull. mar. Sci. 49(1–2): 162–185), but it could not be assigned to any known family. Two larger juvenile specimens have now been obtained, one collected near the surface in the eastern Pacific Ocean and the other rehydrated from a dried specimen originally recovered from the stomach of an Alepisaurus. A photograph of the latter specimen before dehydration was found among the unpublished notes of S. S. Berry. The squid are characterized by very large fins that dwarf the rest of the animal. The fins are terminal in position, mostly posterior to the mantle muscle. The tentacles are similar to the arms in general form, but are much more robust. Tentacle suckers are in eight series, whereas the crowded arm suckers constitute more than two series on some arm pairs. The distal portions of the arms and tentacles taper abruptly to thin vermiform filaments. The funnel cartilage of the net-collected juvenile is oval and the buccal connectives to Arms IV are ventral. Although some characters indicate a likely relationship with the chiroteuthid/mastigoteuthid group of families, the brachial crown differs from that found in any known family. Based upon these three specimens and the photograph, it is concluded that the squid represent a family not previously recognized by science. This family is named Magnapinnidae, with the type species Magnapinna pacifica n. gen., n. sp., the holotype of which is the net-collected juvenile. Although all three specimens are included in the family and genus, the possibility exists that the paralarva and the rehydrated specimen are not conspecific with the holotype. Therefore, paratypes are not designated.

Description: A brief summary of the current capabilities of a high resolution global numerical prediction model towards resolving the life cycles of hurricanes is first presented. Next, we illustrate the results of season long integrations for the years 1987 and 1988 using the observed sea surface temperature (SST) anomalies over the global oceans. The model being used here is the FSU atmospheric global spectral model at the horizontal resolution of T42 and with 16 vertical layers. The main emphasis of this study is on hurricane tracks for these and for global warming experiments. The global warming scenarios were modeled using doubled CO2 and enhanced SST anomalies. The model being atmospheric does not simulate the ocean, and SST anomalies need to be prescribed. It is assumed in these experiments that the SST anomalies of the doubled CO2 world appear similar to those of the current period but that they are slightly warmer over the global tropics. That is determined using a simple proportionality relationship requiring an enhancement of the global mean SST anomaly over the tropics. Such an enhancement of the SST anomaly of an El Nino year 1987 amplifies the SST anomaly for the El Nino of the double CO2 atmosphere somewhat. The La Nina SST anomalies were similarly enhanced for the double CO2 atmosphere during 1988. These hurricane season experiments cover the period June through October for the respective years. It was necessary to define the thresholds for a model simulated hurricane; given such a definition we have compared first the tracks and frequency of storms based on the present day CO2 simulations with the observed storms for 1987 and 1988. Those comparisons were noted to be very close to the observed numbers of the storms. The doubled CO2 storms show a significant enhancement of the frequency of storms for the La Nina periods, however there was no noticeable change for the El Nino experiments. We have also run an experiment using the SST anomalies from a triple CO2 climate run made at the Max Planck Institut at Hamburg, This experiment simulated some 7 hurricanes over the Atlantic Ocean. The intensity of hurricanes, inferred from maximum winds at 850 mb, show that on the average the storms are slightly more intense for the double CO2 experiments compared to the storms simulated from current CO2 conditions. The triple CO2 storms were slightly stronger in this entire series of experiments.

Description: A study of the echo peak amplitudes from known nodule areas is initiated to observe the acoustic response for varying nodule abundances and number densities. A statistical study of the peak amplitudes from different nodule areas confirms that the coefficient of variation is the highest for medium nodule abundance and number density. Echo fluctuation study based on the Rician probability density function (PDF) establishes that the non‐nodule sediment bottom contributes to less scattering, i.e., it is a microtopographic type, whereas scattering is dominant in the nodule‐bearing areas. The spectral studies are conducted on depth data of different areas. This study ensures that the signal scattering in the nodule bottom area is due to the nodules lying on the seabed rather than the large / small‐scale topographic variations. The study based on Poisson PDF for nodule area confirms this fact again. Agreement between the nodule distribution and the Poisson distribution parameter is clearly seen. Such a relation is not observed in the case of Rician density functions.

Description: Plastic debris accumulates in the marine environment following its use in agricultural, industrial and social activities. Its ultimate fate is accomodation in sediments where it may persist for times up to centuries or longer. There appears to be an increasing flux of materials with time and an increased areal coverage of the benthos. Impacts upon bottom organisms can take many forms. Systematic monitoring tactics for the extent of seafloor coverage by plastics are yet to be incorporated into national programs.

Description: In this study, the impact of oceanic data assimilation on ENSO simulations and predictions is investigated. The authors’ main objective is to compare the impact of the assimilation of sea level observations and three-dimensional temperature measurements relative to each other. Three experiments were performed. In a control run the ocean model was forced with observed winds only, and in two assimilation runs three-dimensional temperatures and sea levels were assimilated one by one. The root-mean-square differences between the model solution and observations were computed and heat content anomalies of the upper 275 m compared to each other. Three ensembles of ENSO forecasts were performed additionally to investigate the impact of data assimilation on ENSO predictions. In a control ensemble a hybrid coupled ocean–atmosphere model was initialized with observed winds only, while either three-dimensional temperatures or sea level data were assimilated during the initialization phase in two additional forecast ensembles. The predicted sea surface temperature anomalies were averaged over the eastern equatorial Pacific and compared to observations. Two different objective skill measures were computed to evaluate the impact of data assimilation on ENSO forecasts. The authors’ experiments indicate that sea level observations contain useful information and that this information can be inserted successfully into an oceanic general circulation model. It is inferred from the forecast ensembles that the benefit of sea level and temperature assimilation is comparable. However, the positive impact of sea level assimilation could be shown more clearly when the forecasted temperature differences rather than the temperature anomalies themselves were compared with observations.

Description: This paper presents trace element and Sm-Nd isotope data on the Mönchalpgneiss in order to compare the geochemistry of the two polymetamorphic igneous suites that comprise over 30% of the Austroalpine Silvretta nappe. The first are the so-called "Younger Orthogneisses" of the "Fliielagranitic Association" and the second are the "Older Orthogneisses" including the Mönchalpgneisswhich are associated with metagabbros, metadiorites, metatonalites and metagranitoids. U-Pb zircon results from the Mönchalpgneiss are indicative of anatectic processes in late Cambrian to Ordovician times. A volcanic-arc (VA) tectonic environment during intrusion explains the direct association of gabbroic and metagranitoid rocks in the Engadine area. This model is in line with the distribution of major, trace and rare earth elements in these anatectic rocks. However, the significance of the geochemical results remains ambiguous, since the average continental crust and paragneisses of the Silvretta also show VA-type signatures in the respective diagrams. Nd model ages on four Mönchalpgneiss whole-rock samples from the type locality are closely grouped around 1.70 Ga, which is a commonly obtained value for European continental crust. This age is interpreted to be the result of a homogeneous mixture of different crustal components

Description: A description of egg masses from Gonatus frabricii (Lichtenstein) caught with pelagic trawl in the Norwegian Sea is given. The eggs were kept together in a single layer between two mucous membranes, and the pieces collected appeared to be fragments of more extensive structures torn apart by wear from the sampling gear. No embryos were observed in the eggs, and none of the eggs showed any staining for five enzyme systems analyzed by isoelectric focusing. Either the eggs were caught shortly after spawning and fertilization, or the lack of embryonic tissue reflects the fact that most of the eggs were caught in water colder than 0°C. The development rate at this temperature is expected to be very slow.

Description: The South Tasman Rise is a large submarine plateau of continental origin, located south of Tasmania. In the light of satellite‐derived gravity data and shipboard swath‐bathymetry and magnetic data collected in 1994 in the South Tasman Rise region, this paper re‐examines the sea‐floor spreading history of the surrounding ocean basins (northeastern Australian‐Antarctic Basin and southwestern Tasman Sea). This information is synthesised in seven plate tectonic reconstructions of the South Tasman Rise region from the mid‐Cretaceous (95 Ma) to the Early Oligocene (34 Ma). Our interpretation and model confirm that the South Tasman Rise is composed of two distinct terranes. A western domain, limited to the west by a transform margin along the Tasman Fracture Zone and to the east by a N170°E oriented boundary at 146.5°E, was initially attached to Antarctica. The western terrane rifted away from Antarctica in the Late Paleocene/Early Eocene and underwent severe wrench deformation as the Antarctic plate moved southward relative to the Australian plate. Shear motion continued to shape the Tasman Fracture Zone transform margin until the Early Miocene (chron 6B, 23 Ma) after which the Southeast Indian Ridge axis cleared from the western edge of the South Tasman Rise. An eastern domain limited to the east by a boundary at 146.5°E, rifted off from Tasmania and the East Tasman Plateau. After an initial phase of stretching between Tasmania, the East Tasman Plateau and the Lord Howe Rise that lasted until the mid‐Cretaceous, sea‐floor spreading in the Tasman Sea started in the Late Cretaceous (chron 34y) north of the East Tasman Plateau. Seismic, magnetic and gravity profiles between the eastern South Tasman Rise and the East Tasman Plateau suggest that sea‐floor spreading began between the two microcontinental blocks in the Late Cretaceous (ca chron 33y) and failed shortly after (chron 30y).

Description: The female of the harpacticoid Cholidya polypi Farran, 1914, is redescribed and the male is described for the first time. This copepod parasite of octopuses, reported previously only from Benthoctopus (= Polypus) ergasticus off Ireland, is here documented from the North Atlantic east of Florida on Tetracheledone spinicirrus and off North Carolina and New Jersey on Bathypolypus anticus, and from the northeastern Pacific west of Oregon and Washington on Graneledone pacifica and off central California on Graneledone spp.

Description: Statolith morphology of the giant squid Architeuthis sp. from southern African waters is illustrated. The most characteristic features are identified, particularly the wing shape and position, which are described for the first time.

Description: The morphology of a preserved octopod is significantly affected by the condition of the animal at the time of fixation, whether live or dead. When unknown, this condition can be assessed by examining the degree of contraction of the radula support muscle. Specimens fixed post‐mortem have a relaxed radula support muscle. This muscle is contracted in specimens plunged into preservatives alive. The degree of contraction of this radula support muscle facilitates identification of both fixation‐induced and fixation‐independent character states in octopod systematics.

Description: An uncritical compilation of New Zealand Mollusca by Spencer & Willan in 1996 cites 90 species of cephalopod as recorded from New Zealand waters (excluding the Kermadec Islands) to 31 December 1993. Seventeen of these 90 species are octopods and the status of five is in need of immediate revision. Pareledone sp. and Octopus sp. have since been transferred to the genera Graneledone and Benthoctopus, respectively, although both species await description. Haliphron atlanticus Steenstrup, 1860 (as Alloposus mollis Verrill, 1880), Ocythoe tuberculata Rafinesque, 1814, and Octopus dofleini (Wulker, 1910) are cited as occurring within New Zealand waters solely on the basis of identification of beaks or tissue remains from gut contents of longdistance foraging marine predators. The appropriateness of including these three species in the New Zealand fauna is evaluated in the light of thorough examination of extensive cephalopod collections from New Zealand waters.

Description: A total of 1,014 measures of sediment shear strengths were measured by means of miniature vane shear and fall cone tests on five gravity cores collected in Eckernfo‐erde Bay, Baltic Sea. Paired t test was used to compare the shear strengths measured by the two methods. It was found that fall cone strength calculated with Wood's K60value (0.29) overestimates the vane shear strength by 0.15 kPa (a = 0.001) and the sample mean of the fall cone strength is 4.1% higher than the mean of the vane shear strength. However, fall cone strength calculated with Hansbo's K60 value (0.24) underestimates the vane shear strength by 0.88 kPa (a = 0.001), and the sample mean of the fall cone strength is 13.8% less than the mean of the vane shear strength. Both calculated fall cone strengths are significantly different from the vane shear strength, with a p value of less than 0.001. Regression analysis of the Echernfoerde Bay data indicates that a new K60 value is 0.275 with a confidence interval (a = 0.01) from 0.2704 to 0.2786. Paired t test shows that there is no significant difference between miniature vane shear and fall cone tests for these samples if the fall cone strength is calculated with K60 = 0.275.

Description: In this paper the performance of the global coupled general circulation model (CGCM) ECHO-2, which was integrated for 10 years without the application of flux correction, is described. Although the integration is rather short, strong and weak points of this CGCM can be clearly identified, especially in view of the model's performance of the annual cycle in the tropical Pacific. The latter is simulated with more success relative to the earlier version, ECHO-I. A better representation of the low-level stratus clouds in the atmosphere model associated with a reduction in the shortwave radiative flux at the air-sea interface improved the coupled model's performance in the southeastern tropical oceans, with a strongly reduced warm bias in these regions. Modifications in the atmospheric convection scheme also eliminated the AGCM's tendency to simulate a double ITCZ, and this behavior is maintained in the CGCM simulation. Finally, a new numerical scheme for active tracer advection in the ocean model strongly reduced the numerical mixing, which seems to enhance considerably the level of interannual variability in the equatorial Pacific. One weak point is an overall cold bias in the Tropics and midlatitudes, which typically amounts to 1°C in open ocean regions. Another weak point is the still too strong equatorial cold tongue, which penetrates too far into the western equatorial Pacific. Although this model deficiency is not as pronounced as in ECHO-1, the too strong cold tongue reduces the level of interannual rainfall variability in the western and central equatorial Pacific. Finally, the interannual fluctuations in equatorial Pacific sea surface temperatures (SSTs) are too equatorially trapped, a problem that is also found in ocean-only simulations. Overall, however, the authors believe that the ECHO-2 CGCM has been considerably improved relative to ECHO-1.

Description: Abstract The famous association of metagabbros, eclogites, glaucophanites, jadeite rocks and ultramafics from the island of Syros forms a distinct lithostratigraphic or tectonic unit. It is interpreted as a high-pressure metamorphic ophiolite suite. This paper provides geochemical and Sr-isotope constraints on the geotectonic setting in which the magmatic protoliths of the Syros metabasites were formed. A compositional gap exists between the metagabbros with Mg-numbers [Mg# = Mg/(0.85Fetot + Mg) atomic ratio] of 0.75-0.88 on the one hand and eclogites and garnet-glaucophanites on the other hand with Mg# of 0.35-0.62, and maximum total iron contents of up to 18 wt.% FeOtot. Metagabbros from various localities and glaucophanites collected around Manna form geochemically coherent groups with smooth correlations between compatible as well as immobile incompatible elements and Mg#. By contrast, the behaviour of immobile incompatible elements, and to some extent also of compatible elements, is highly unsystematic in the eclogites and garnet-glaucophanites. Also, the more mobile elements display a wide scatter in all rocks. This, in conjunction with the unsystematic variation of Sr-isotopes, is thought to be due to secondary alteration. From the strong correlation of Ni and Cr with Mg# and the flat REE patterns lacking Eu-anomalies, a cumulus nature is inferred for olivine, clinopyroxene, and spinel, associated with intercumulus formation of plagioclase in the magmatic protoliths of the metagabbros. There is no direct genetic link between these rocks and the precursors of the Manna-type glaucophanites with REE characteristics typical of N- to T-type MORB. The extremely high geochemical diversity of the eclogites and garnet-glaucophanites from Syros favours individual evolution of their protoliths in small magma bodies as suggested for superferric eclogites from the Western and Ligurian Alps, as well as the ferrogabbros from the ophiolites of the Northern Apennines. From the geochemistry of the Syros metabasites along with the initial 87Sr/86Sr ratios of the metagabbros between 0.7031 and 0.7033, as well as an eNd value of 7.7 from a garnet glaucophanite, the magmatic protoliths are inferred to have formed in a back-arc setting. By analogy to the association of gabbros and ferrogabbros adjacent to the Atlantis II fracture zone of the SW Indian Ridge, we further suggest an origin at a spreading ridge in proximity to a transform fault.

Description: Evolution of the Caribbean Plate can be modeled by motions about six successive rotation poles. Opening of Cayman Trough has occurred since 49.5 Ma through westward motion of the Caribbean Plate, eastern Greater Antilles and Chortis Block. Before 49.5 Ma, the eastern Greater-Antilles were west of Cuba, and the southeastern margins of Yucatan and the Nicaragua Rise (Chortis) were aligned. From 67.5 to 49.5 Ma the Caribbean Plate rotated clockwise, opening the Yucatan Basin. From 100 Ma to 67.5 Ma, the Caribbean Plate, with Cuba attached, moved along the southeastern margin of Yucatan-Chortis. At 130 Ma it was attached to northwestern South America.

Description: Microspectralphotometric examinations of various recent pollen point to a different sporopollenin chemistry of the different taxa which is distinguishable by the UV-VIS absorptionspectra. The measurement areas have a diameter of 6 micron, by which several measurements for the spectra control in one pollen grain are possible. Labaratory experiments with chemical treatments as used by palynological preparation, show a clear change in the sporopollenin chemistry whichcould be identified by the absorption spectra. Therefore a new preparation technique for fossil and recent palynomorphs has to be developed to avoid chemical changes. First investigations of recent and fossil Pinus pollen have been clone on material from various facies types and a sediment core. The variations in the absorption spectra of the pollen indicate the different chemical influence of different facies types which could be used for facies analyses. Furthermore, significant changes in the absorption spectra are useful to identify reworked pollen or pollen with a different burial history. Zusammenfassung: Vergleichende mikrospektralphotometrische Untersuchungen der UV-VIS Absorptionsspektren verschiedener rezenter Pollen-Taxa zeigen, daß die Zusammensetzung bzw. Struktur des Sporopollenins bei verschiedenen Taxa variiert und daß diese anhand der Absorptionsspektren klar unterschieden werden kann. Die gemessene Fläche auf den jeweiligen Pollen hat einen Durchmesser von 6 j.lm, so daß mehrere Kontrollmessungen an einem Pollen möglich sind. Laborversuche an rezenten Pollen zeigen, daß chemische Einflüsse (z. B. HN03, Acetolyse) deutlich meßbare Veränderungen in der Struktur des Sporopollenins verursachen. Um Veränderungen des Sporepollenins durch die chemische Probenaufbereitung auszuschließen, wurde eine neue Präparationsmethode für fossile und rezente Palynomorphen entwickelt.

Description: The free surface version of the GFDL model is used to study inflow and outflow through the Danish Straits, which connect the Baltic with the North Sea. Three problems are addressed: (i) the piling up of inflowing water in the Arkona basin; (ii) the transport ratios between Belt and Sound; (iii) the dominance of hydraulic or geostrophic control. Model results show that a cyclonic eddy (dome) is formed by the inflowing saline water that prevents this water from passing rapidly into the Bornholm basin. This eddy is enforced with increasing inflow due to a sea level difference between Kattegat and western Baltic. If density gradients along the straits are weak and the flow is dominantly driven by sea level differences between Kattegat and Baltic, the well-known ratio of 70% : 30% for the transports through Belt and Sound are confirmed. Strong density gradients can change this ratio considerably, especially in the outflow case, when the light water of the Baltic flows against the heavier water of the Kattegat. Under variable wind conditions, no fixed ratio is found. The flow in the Straits is geostrophically controlled; however, the strong baroclinic density field does not allow us to derive the transport simply from sea level inclination.

Description: ana marit., 27 (3/6): 145-150, 2 figs.; Frankfurt a. M.] According to the (neo-)Darwinian theory of evolution the appearance of "design" and optimization of biological properties are the results of natural selection and not of teleology. An opti· mization by selection is only possible for entities which are able to reproduce ("units of selection"). The "unit-of-selection"-problem will be discussed in relation to the atomism-holism-continuum of ecological and evolutionary concepts which range from Dawkins' "selfish gene" to LoveJock's "Gaia". Special emphasis will be given to the discussion of the group-selection problem which seems to be the critical breakpoint along this continuum. It will be shown that optimization through natural selection is only possible for units which can multiply and preserve their identity to a sufficient degree through multiplications. Such units are called replicators. Associations, communities, ecosystems and the biosphere do not qualify as replicators.

Description: In Sedimenten aus flachen Bohrungen in der Nordsee wurden gasförmige Kohlenwasserstoffe gefunden. Kohlenstoff- (Methan bis Propan) und Wasserstoff-Isotopanwerte lassen auf eine Mischung von Gasen bakterieller und thermischer Entstehung schließen. Die thermischen Gase sind in größerer Tiefe aus überwiegend mariner organischer Substanz entstanden und in die oberflächennahen Sedimente migriert. [Methane through pentane have been found in sediments from shallow North Sea boreholes. Carbon (methane through propane) and hydrogen (methane) isotope ratlos indicate both bacterial and thermal origins. The gases of thermal origin are interpreted as having been generated at considerable depth from predominantly marine source rocks and then to have migrated into the overlying sediments.]

Description: For the purpose of this study, 5 311 post recruit of Illex coindetii were collected from the fishery of the Galician shelf, with sizes ranging from 32 to 379 mm dorsal mantle length (ML). Samples were taken monthly from November, 1991 to October, 1992. Sexual maturation, spawning season and population structure of Illex coindetii were analyzed. The spawning season extended throughout the year reaching a peak in July-August, with size at first maturity in males, 128 mm ML and in females, 184 mm ML. Males mature at a smaller size and attain lower size (279 mm ML) than females (379 mm ML). The sex ratio of the whole population sampled was slightly biased towards males, nevertheless monthly variations observed and the ratio obtained (1.09 : 1) does not suggest that there is spatial segregation by sexes in the fishing ground. From the total sample, 185 males and 281 females, covering the whole range of ML's, were randolmy separated out to calculate maturation indices. A correlation between the subjective scales and the values of these indices was established in both sexes. The nidamental gland length proved to be a reliable parameter for distinguishing between stages of maturity in females. The fecundity of the species varied between 3 500 and 285 000 oocytes, (the most frequent range being from 30 000 and 200 000 oocystes) in the ovary and the oviducts. The principal axis in the oviduct contained 2 331 ± 912 eggs. The number of spermatophores in the spermatophoric sac varied between 81 and 1 555, and it was observed that the number and the length of the spermatophores tended to increase with size of the males. Illex coindetii may be considered as an intermittent spawner.

Description: Most cephalopods are voracious and very mobile predators with highly developed sense organs that rival the equivalent vertebrate sense organs in complexity. A brief description is given of cephalopod predation and the sense organs that are directly, or indirectly, involved: (i) the vertebrate‐like lens eyes with their complex extraocular eye muscle system; (ii) the epidermal head and arm lines which are analogous to the lateral lines of fishes and aquatic amphibians; (iii) the vestibular analogue statocysts with receptor systems for linear (gravity) and angular accelerations; (iv) the proprioceptive neck receptor organ which controls head‐to‐body positions; (v) the sucker and muscle mechanoreceptors; and (vi) the contact and distance chemoreceptors. In addition, the possibility of hearing is discussed.

Description: Parasites were collected from 1,200 short-finned squid (Illex coindetii, Todaropsis eblanae) caught as by-catch in a multispecies trawling fishery in the northwest Spanish Atlantic waters in 1992-1993. Parasites found included six species of helmiths, three tetraphyllidean cestodes (Phyllobothrium sp., Pelichnibothrium speciosum, Dinobothrium sp.), two trypanorhyllidean cestodes (Nybelinia yamagutii, Nybelinia lingualis), and one ascarioid nematode (Anisakis simplex B). Two of these parasites (Phyllobothrium sp., A. simplex B) which could be recognised as component species, were used in analyses of host-parasite relationships. Levels of infection varied significantly with host size or stage of maturation for both squid species. Regional variation in infection level seems attributable to geopgraphical variation in variability of prey, discreteness and movements of host populations and to size or age-related changes in the prey selection of their host. Parasite evidences suggest that both ommastrephid squids are sympatric species sharing similar econiches, and serve as diet for large top predators (selachians and marine mammals) of Northeast Atlantic. Parasites may also be useful as an indirect indicator of the migratory habits of the squid.

Description: This study shows that calcium carbonate plays an important role as a cementing agent of various marine sediments. The measured vane shear strength of marine soil samples is shown to vary with depth and is strongly correlated with the calcium carbonate content. The results show that an increase in calcium carbonate of 1% causes an increase in shear strength of about 10 kPa. Moreover, under accumulating self‐weight, consolidation is found to be enhanced by calcium carbonate. It was also found that both the cementation and condensation due to calcium carbonate are the major factors accounting for the strength development of marine sediments, beside consolidation. These effects are often greater than those due to grain size effects.

Description: A model is presented which tests the representation of the maturity process in terms of gonadosomatic indices (GSI) in chokka squid Loligo vulgaris reynaudii. It assumes that the true maturation process is reflected by the results of histological investigation, which cannot be used in large-scale ecological work in the field. However, the maturity scales used in ecological studies define some morphological categories which can be linked directly to microscopic development. Therefore, the overlap of GSI ranges for each morphological maturity category may be used to judge how well the GSIs represent the histological stages. Results have shown that the overlap is large and that GSI cannot be recommended as adequately reflecting the maturation process in squid. A morphological scale of maturity with possible broad applications in exploited families of squid is proposed as a better representation of the maturation process than GSI.

Description: Morphological differences between paralarvae of two loliginid squid species common in southern African waters (Loligo vulgaris reynaudii and Lolliguncula mercatoris) are described. The differences are: Loligo — "cheek patches" consisting of four dark chromatophores, nine large dark dorsal chromatophores on the mantle, tentacular clubs broad and much wider than tentacle stalks, proximal row of three club suckers with others tetraserial, suckers large enough to appear crowded on the club surface; Lolliguncula — "cheek patches" with three dark chromatophores, two pairs of" large, dark dorsal chromatophores on the mantle, tentacular clubs narrow, proximal club suckers arranged in three pairs, suckers small, not particularly crowded. Relationships with other myopsids are briefly discussed.

Description: The chemical composition of sediments from the Reykjanes Ridge is controlled by allochthonous and autochthonous processes. The surface sediments are characterized by relatively high contents of calciumoxide and strontium. Calcium and strontium dominate in the carbonate phase due to the high content of biogenic carbonate. A high percentage of iron and manganese are bound to oxides and hydroxides. An indication of hydrothermal activity was not observed. A considerable portion of adsorbed barium is transported in clay minerals. The higher amounts of aluminium in glacial sequences indicate an enhanced input of terrigenous material; the increase of stable bonding elemen~s points toward the large influence of detrital minerals. The distinct differences in the bonding characteristics of elements in these marine sediments in comparison to fluvial and coastal - deposits could be due to the different environmental conditions.

Description: The mean pressures required to collapse gas vesicles in turgid cells of cyanobacteria from the Baltic Sea were 0·91 MPa (9·1 bar) in Aphanizomenon flos-aquae, 0·83 MPa in Nodularia sp. collected from the main deep basins and 0·34 MPa in Nodularia from shallower coastal regions. The gas vesicles were strong enough to withstand the depth of winter mixing, down to the permanent halocline (60 m in the Bornholm Sea, 90 m in the Eastern Gotland Sea) or to the sea bottom (30 m or less in the shallow Arkona Sea and Mecklenburg Bight). The cyanobacteria had low cell turgor pressures, within the range 0·08–0·18 MPa. The colonies were highly buoyant: the Aphanizomenon colonies floated up at a mean velocity of 22 m per day and the Nodularia colonies at 36 m per day. The colonies remained floating when up to half of the gas vesicles had been collapsed. In summer the cyanobacteria were mostly restricted to the water above the thermocline and in calm conditions their concentration increased towards the top of the water column. A series of colony concentration profiles indicated that, following a deep mixing event, the population of colonies moved upward with a net velocity of 22 m per day, similar to the colony floating velocity. This demonstrated that the buoyancy provided by gas vesicles would give a selective advantage to populations of cyanobacteria by enabling them to float into the higher irradiance of the near-surface water.

Description: In this study the antifouling activity was investigated of a series of chemically related, halogenated furanones isolated from Delisea pulchra (Greville) Montagne, a red alga which is rarely fouled in the field. The metabolites were tested in laboratory assays against representatives of the three major groups of fouling organisms, the barnacle Baianus amphitrite amphitirite Darwin, the macroalga Ulva lactuca Linnaeus and a marine bacterium (strain SW 8). Settlement of barnacle cyprid larvae was strongly inhibited, with an EC50 of 〈 25 ng·mr1 (25 ppb) for some compounds. The settlement and growth of algal gametes was also strongly inhibited, in some cases at concentrations as low as 25 ng·cm-2 • Growth of the marine bacterium SW8 was inhibited more strongly than by the common antibiotic gentamicin. Overall, activity of the D. pulchra metabolites was comparable to that of the heavy metals and biocides currently used in antifouling paints. However, no single compound was most active in all tests and some metabolites effective against one organism showed Iittle or no activity a·gainst the others. The high but variable level of activity of the D. pulchra metabolites, coupled with their small size, relative stability, and ability tobe synthesized suggest their potential use as active ingredients in antifouling coatings.

Description: The seasonal cycle over the tropical Pacific simulated by 11 coupled ocean–atmosphere general circulation models (GCMs) is examined. Each model consists of a high-resolution ocean GCM of either the tropical Pacific or near-global means coupled to a moderate- or high-resolution atmospheric GCM, without the use of flux correction. The seasonal behavior of sea surface temperature (SST) and eastern Pacific rainfall is presented for each model. The results show that current state-of-the-art coupled GCMs share important successes and troublesome systematic errors. All 11 models are able to simulate the mean zonal gradient in SST at the equator over the central Pacific. The simulated equatorial cold tongue generally tends to be too strong, too narrow, and extend too far west. SSTs are generally too warm in a broad region west of Peru and in a band near 10°S. This is accompanied in some models by a double intertropical convergence zone (ITCZ) straddling the equator over the eastern Pacific, and in others by an ITCZ that migrates across the equator with the seasons; neither behavior is realistic. There is considerable spread in the simulated seasonal cycles of equatorial SST in the eastern Pacific. Some simulations do capture the annual harmonic quite realistically, although the seasonal cold tongue tends to appear prematurely. Others overestimate the amplitude of the semiannual harmonic. Nonetheless, the results constitute a marked improvement over the simulations of only a few years ago when serious climate drift was still widespread and simulated zonal gradients of SST along the equator were often very weak.

Description: Simulations with an ocean general circulation model and a hybrid coupled model reproduce well the observed principal spatial mode (PSM) of variation of the tropical Pacific ocean/atmosphere system. The model results show the origins of the PSM to be a coupled ocean/atmosphere mode and suggest this phenomenon is not a natural mode of the tropical Pacific Basin alone. Air-sea interactions amplify the mode variability by a factor of 5–6 over the strength it would have in a purely random atmosphere and so it obtains climatological importance. These same interactions introduce the PSM to the atmosphere. The PSM of interannual variability is not directly driven by the annual cycle. But its time scale does depend importantly on the fact that the ocean-atmosphere coupling strength varies with respect to the annual cycle. The mode appears to be rather sharply peaked in wave number space but broadbanded in frequency space so that identifying it with a temporal designator, as has been done in the past is apt to be misleading.

Description: Megafauna on bioherms (large biological structures) of the scleractinian coral Lophelia pertusa at 240-290 m depth in the Haltenbanken- Fmyabanken area was investigated by video-recording. Sixteen transects from soft bottom with scattered patches of stones below bioherms to top of bioherms were analysed. Fauna patterns were related to the near-bottom currents. The orientation of the gorgonianParamuricea placomus was used as an indicator of the direction of the main currents at the bioherms. The bioherms were 2 to 31 m high, and had a basal area ranging from 1 500 to 50 600 m2. 36 taxa were identified, of which five taxa only occurred on the bioherms, and five only on the soft bottom with scattered stones. The diversity, H', was highest in the zone of dead Lophelia, and lowest on the silty clay. None of the 26 taxa observed on stones were spesific for this habitat, but occurred also on the bioherms or the soft bottom. The area with Lophelia rubble, near the basis of the bioherms, had the lowest number of taxa (15), but the highest average density of individuals (7.92 ind./1Om2). Different sponges, gorgonians (Paragorgia arborea, Paramuricea placomus, Primnoa resedaeformis), squat lobsters (Munida sarsi), redfish (Sebastes spp.) and saithe (Pollachius virens) dominated in terms of individuals per area. Diversity, density of sponges and density of gorgonians were highest on the down-current side of the bioherms. Saithe were observed with highest densities near the basis of the bioherms, on the up-current side, while redfish had highest densities on the parallel-current side of the bioherm top. These results indicate that near bottom currents and turbulence are factors affecting the fauna on Lophelia bioherms.

Description: There have traditionally been strong ties between physiology and ecology and between ecology and systematics. Although the connection between physiology and systematics has not been adequately realized, there are important reasons to strengthen it. Much of physiology has been based on the comparative method, which implies a knowledge of evolutionary relationships. Systematics, on the other hand, relies on the distribution of characteristics among groups of organisms, and should include characteristics of their lifestyles, including performance. Lifestyle characteristics, which are studied by physiologists, ecologists, or behavioral scientists, may be comparatively recent adaptations or may be constrained by evolution similarly to the morphological characters traditionally studied by systematists. Working together, these disciplines can provide better explanations of adaptations and evolutionary constraints about which not much is known for the great majority of cephalopod taxa.

Description: The morphological and physiological adaptations that the cephalopod sensory organs and nervous system underwent during the course of evolution are briefly summarized. Special emphasis is paid (i) to the vertebrate‐like lens eyes with their complex extraocular eye muscle system, (ii) to the vestibular analogue statocysts with hair cell receptor systems for linear and angular accelerations and an elaborate afferent and efferent nerve supply, (iii) to the epidermal head and arm lines which are analogous to, and as sensitive as, the lateral lines of fishes and aquatic amphibians, (iv) to the giant fibre system for escape jetting, and (v) to the highly centralized brain which is capable of different forms of learning and memory.

Description: Statolith microstructure was studied in eight specimens of the boreal sepiolid Rossia pacifica (mantle length ranging from 45to 90mm) caught on the continental slope of Northwest Bering Sea. Growth increments were presented in all ground statoliths and were narrow and uniform width (average 3.2 - 3.3µm). They were grouped into inner opaque and outer translucent growth zones. The total number of growth increments within the statoliths of mature males (75-78) was lower than of mature females (95-117 increments). Assuming growth increments to be laid down daily, the life span from hatching to death of R. pacifica in the Bering Sea may be 4-5 months.

Description: The distribution and abundance of six species of Sepia and one of Rossia were studied during six west coast and three south coast bottom trawl surveys off South Africa. The two most common species on both coasts were Sepia australis and S. hieronis. Both were most abundant on the northern West Coast (Orange River and Port Nolloth areas) and were sparsely ditributed over the rest of the region. The depths of greatest abundance were 60-190m (S. australis) and 110-250m (S. hieronis). The highest biomass indices were recorded on the species also peaked in May 1988 on the South Coast (803 tons). The environmental factors most influencial in the distribution of the two species were bottom oxygen concentrations between 1,5 and 3,5ml-l-1. The two species were most abundant at relatively low temperatures: on the West Coast catches peaked when the S. simoniana and S. typica) are usually found in shallow water (〈100m), mainly on the South Coast. Rossia enigmatica, a sepiolid, is most abundant in 400-500m of water, generally on the West Coast.

Description: A new type of epibenthic sledge is presented, which possesses an additional supranet above the epinet. Both nets are closed by an opening/closing device in the water column. The new construction allows a selective catch ofhigher suprafauna, which swims 1–1.33m above the seafloor, and a good discrimination between real suprafauna and epifauna. In total, 79581 Peracarida were sampled at 8 stations at about 75°N and 12°W, off Greenland. Of these, Isopoda were usually the most abundant group in the epinet, Amphipoda in the supranet. At the stations where suprafauna was abundant, the numbers of Mysidacea were usually higher in the epinet than in the supranet, probably due to differences in food supply, i.e. the enrichment of food in the benthic boundary layer.

Description: Observations of the dinoflagellate Dinophysis norvegica in the Baltic Sea during the summers of 1991–1993 indicate that maximal abundances (c 40–150 × 103 cells l-1) were found at the thermocline, typically at 12°C. Maximum densities were usually between 12 and 15 m where 2·9% and 1·5% of surface photon irradiances, respectively, were measured. No diel vertical migration was observed, and cell densities in the mixed layer were always low. Photosynthesis versus irradiance measurements with an oxygen electrode indicated that these populations had a P max of 2·47 [coefficient of variation (CV) 7·3%] and 3·4 (CV 4·7%) mg O2 mg Chl a -1 h-1, and compensation values of photon irradiance were 16·5 and 83 μmol m-2 s-1 in 1992 and 1993, respectively. Both oxygen electrode and 14C light/dark bottle measurements indicated that D. norvegica had very little net photosynthesis at the depths where it was most abundant; it would have had about 2·5-fold greater capacity at photon irradiances present closer to the surface. Calculated carbon doubling times via photosynthesis averaged 4–11 months. There was no observable diel rhythym of DNA synthesis, suggesting that either D. norvegica was not dividing synchronously (asynchronous division is common in heterotrophs) or not dividing at all. Electron microscopy did not reveal the presence of food vacuoles, but feeding and digestion could have been extracellular. The data suggest that this species is a mixotroph which received its primary nutrition via heterotrophic means during our observation periods in the summers of 1991–1993.

Description: Larvae of Siboglinum poseidoni were reared in the laboratory. About 6 weeks after recovery from the central Skagerrak the larvae develop a small tentacular bud. On the opposite side a stomodaeum is formed. Electron microscopy of suitable sections shortly in front of the tentacular bud reveals a ciliated opening and tract. In the trunk this tract is reduced to a small tube by bulging endoderm cells containing large amounts of yolk. The lumen is obscured by densely packed cilia. In more advanced stages extracellular symbiotic bacteria occur within this transient digestive tract. They appear to be taken in via the transient mouth. As development progresses the mouth and ciliated foregut close. In the trunk of adult specimens the space between the dorsal and the ventral vessel is occupied by bacteriocytes forming the trophosome. The lumen ofthe digestive tract is reduced to small ciliated spaces. The tentacle develops opposite to the transient mouth and hence dorsally, while the main nerve trunk is ventral. More advanced larval stages closely resemble an elongated annelidian metatrochophora. A relationship between Vestimentifera (Obturata) and Pogonophora (Perviata) is confirmed and the placement of both groups within the phylum Annelida suggested.

Description: In a midoceanic region of the northeast Atlantic, patches of freshly deposited phytodetritus were discovered on the sea floor at a 4500 m depth in July/August 1986. The color of phytodetritus was variable and was obviously related to the degree of degradation. Microscopic analyses showed the presence of planktonic organisms from the euphotic zone, e.g., cyanobacteria, small chlorophytes, diatoms, coccolithophorids, silicoflagellates, dinoflagellates, tintinnids, radiolarians, and foraminifers. Additionally, crustacean exuviae and a great number of small fecal pellets, “minipellets,” were found. Although bacteria were abundant in phytodetritus, their number was not as high as in the sediment. Phytodetrital aggregates also contained a considerable number of benthic organisms such as nematodes and special assemblages of benthic foraminifers. Pigment analyses and the high content of particulate organic carbon indicated that the phytodetritus was relatively undegraded. Concentrations of proteins, carbohydrates, chloroplastic pigments, total adenylates, and bacteria were found to be significantly higher in sediment surface samples when phytodetritus was present than in equivalent samples collected at the same stations in early spring prior to phytodetritus deposition. Only the electron transport system activity showed no significant difference between the two sets of samples, which may be caused by physiological stress during sampling (decompression, warming). The chemical data of phytodetritus samples displayed a great variability indicative of the heterogeneous nature of the detrital material. The gut contents of various megafauna (holothurians, asteroids, sipunculids, and actiniarians) included phytodetritus showing that the detrital material is utilized as a food source by a wide range of benthic organisms. Our data suggest that the detrital material is partly rapidly consumed and remineralized at the sediment surface and partly incorporated into the sediment. Incubations of phytodetritus under simulated in situ conditions and determination of the biological oxygen demand under surface water conditions showed that part of its organic matter can be biologically utilized. Based on the measured standing stock of phytodetritus, it is estimated that 0.3–3% of spring primary production sedimented to the deep-sea floor. Modes of aggregate formation in the surface waters, their sedimentation, and distribution on the seabed are discussed.

Description: The diet of Northern Rockhopper Penguins Eudyptes chrysocome moseleyi breeding on Gough Island, south Atlantic Ocean was studied, during November 1984, 1985 and 1986 by stomach content analysis. Rockhopper Penguins fed chiefly on the euphausiids Thysanoessa gregaria, Euphausia lucens and E. similis. Fish and squid were of minor importance by mass but constituted the largest individual prey items.

Description: The Imperial Cormorant Phalacrocorax atriceps is an inshore foraging, diving seabird (Cooper 1985) distributed throughout the southern hemisphere south of 45°S (Watson 1975). A brief description of the diet of the Imperial Cormorant at Marion Island has been published (Blankley 1981). We present here a more comprehensive report based on food samples collected throughout the year.

Description: The western margin of the Tauera Window (Eastern Alps) is defined by a low angle westward dipping fault zone of potently We disp lacement. Ductile deformation of the fault rocks results in a carpet of mylonites up to 400 metres thick. Evidence from shear criteria and the excision of part of the Cretaceous-Tertiary metamorphic edifice both indicate normal displacements, and relative movement of Austroalpine nappe complex towards the west. The Sterzing-Steinach mylonite zone overprints the Alpine nappe edifice. Movements occurred on the cooling path of the Tauern metamorphism, and may be as recent as Middle Miocene. The Kinematics and geometry of the mylonite zone constrain two likely t ectonic explanations that are both compatible with secondary thining of a thick orogenic wedge. (1) Ute the Austroalpine nappe pile due to tectonic unroofing of the Tauern window. (2) Continental escape by east-west stretching of the Alpine orogenic wedge in response to continental collision.

Description: Chemical composition of Zostera marina L. seed and shoots was determined. Morphology and histochemistry of mature seeds were studied by fluorescence, brightfield and scanning electron microscopy to locate storage constituents in the seed. Starch content in the mature seed was 51% and was the major storage reserve in the embryo and a minor component in the testa. Starch in the shoots ranged from 0.3 to 2.3%. Protein, located in the embryo as small protein bodies, comprised about 9.0% of the seed. Protein in shoots ranged from 6–15%. Protein quality of both seeds and shoots resembled corn in composition, and the first limiting amino acid was lysine. Shoots were high in minerals, fiber and ash, while seeds were lower in these constituents. Fat was low (0.3–1.7%) in both shoots and seeds.

Description: The diet of Ommastrephes bartramii (Lesueur, 1821) was determined by analysing the stomach contents of 73 squid caught in the South-West Atlantic Ocean. There were three main prey groups, Cephalopoda (in 82% of the squid stomachs), Osteichthyes (34%) and Crustacea (18%). Cannibalism was common. Squid of the families Histioteuthidae and Enoploteuthidae and other teuthoids were less frequent in the diet. The fish prey was predominantly Myctophidae, of various species. The bulk of the prey was mesopelagic species that migrate into the epipelagic layers at night.

Description: Feeding strategies are different when adult Illex illecebrosus prey on large (trout) and small fish (mummichogs). Attacks on trout are characterized by (1) rotation as the squid changes from tail‐first to head‐first swimming; (2) an approach phase involving rapid acceleration towards the prey; (3) a tracking phase where the squid slowly follows the trout; (4) the capture phase. No tracking phase is present in attacks on mummichogs. These differences in feeding strategies can be explained by performance limitations of the squid jet propulsion system. Head‐first acceleration rates in Illex are low (max. = 12 m • s−2) and maneuverability poor compared to fish. A large fish could thus out‐perform an attacking squid if forced into evasive action. The tracking phase is a type of oceanic stalking strategy designed to bring the squid into close proximity to larger fish. The behaviour is not necessary when attacking small fish due to their low swimming speeds.

Description: Oxygen consumption and ammonia excretion rates were investigated in young Octopus maya (hatching to 139 days old; 0.11–81.23 g wet body weight, BW; 22.5–23.9°C), young squids of Loligo forbesi (hatching to 45 days old; 9.4–115.3 mg BW; 12.3–13.1°C) and young squids of Lolliguncula brevis (2.00–39.98 g BW; 23.8–24.7°C). Except at hatching, oxygen consumption and ammonia excretion rates on an individual basis (M) of these three cephalopods increased linearly with increasing body weight (BW) expressed as M = aBWb . Values of b for oxygen consumption were 0.900, 0.910 and 0.848 and for ammonia excretion were 0.744, 0.809 and 0.751 for O. maya, L. forbesi and L. brevis, respectively. Among the three species the value a varied widely, while b was similar for both oxygen consumption and ammonia excretion rates. Based upon these data, metabolism for hatchlings of O. maya and L. forbesi was estimated to be relatively lower than that of older juveniles. The O/N ratios for hatchlings of O. maya and L. forbesi were relatively high and indicate an apparent dependence upon lipids in the immediate post‐hatching period, followed by standard protein energy utilization thereafter.

Description: The first recorded specimens of Scaeurgus unicirrhus from the South-East Atlantic are described. Five males and two females were captured on the Valdivia Bank, Walvis Ridge, between 24 and 27°S, 400 miles off the Namibian coast. They are compared with specimens caught from other areas, and historical and geographic surveys of the species are made.

Description: Two species of arrow squid, Nototodarus (Oegopsida: Ommastrephidae), are caught in New Zealand waters. The close similarity in most morphometric characters has lead to confusion over the status of the two species. They are distinguished by the number of pairs of suckers on the first right arm; adult males are distinguished by the number of proximal tubercles and the morphology of the distal part of the hectocotylised arm; fresh or frozen specimens can be identified by gel elec‐trophoresis of the enzyme glycerol‐3‐phosphate dehydrogenase. Nototodarus sloanii is found in southern waters and N. gouldi in more northerly waters around New Zealand as well as southern waters of Australia. Differences between the two species are described and notes presented on their biology, abundance, and exploitation.

Description: Change of colour, consistency and pH in contents of the caecum and the stomach of laboratory-maintained long-finned squid Loligo vulgaris reynaudii were determined. There was relatively little variability in any of these parameters of the specimens investigated. Colour and consistency of food or emulsion were used as a basis of analysis of stomach-caecum contents of wild squid. Most squid fed late during the night and/or during the early morning, and the frequency of caecum colour categories did not change much between trawls. Wild squid preyed upon different organisms according to their size. Squid of 69–125 mm dorsal mantle length fed mainly on euphausiids (95% by frequency of occurrence, 87,5% by mass) and those of 126–240 mm mainly on fish (78 and 74,3% respectively) with Bregmaceros?macclellandii and hake as important components. Unidentified fish in the stomachs (i.e. those from which no otoliths were available) probably also belonged to these two species.

Description: Food samples from 27 Buller’s mollymawks Diomedea bulleri from the New Zealand region showed that cephalopods were, by frequency of occurrence and by mass, their preferred food. Fish, crustaceans, and tunicates, in decreasing order of importance, also were taken. Seventeen species of Cephalopoda were identified by their beaks, with 78.5% of individuals belonging to the Ommastrephidae (77% Nototodarus spp.) and 10% to the Histioteuthidae. The diet was compared with that of four other small species of Diomedea, and found to be similar to that of D. chrysostoma, D. irrorata, and D. cauta, but different from that of D. melanophris, whose preferred food is euphausiids. Squid-fishing operations around New Zealand may come into competition with Buller’s mollymawk.

Description: Squid regurgitated by Greyheaded and Yellownosed Albatrosses at the Prince Edward Islands were predominantly two onychoteuthid species, Kondakovia longimana and Moroteuthis knipovitchi. Both squid are characteristic of cold, Antarctic waters and may have been caught south of the Antarctic Convergence, some 350 km to the south of the breeding station. Both albatross species regurgitated similar squid (by species and size), and these squid were similar to those found in previous studies of the diet of Wandering, Sooty and Lightmantled Sooty Albatrosses at the Prince Edward Islands

Description: The development of natural plankton populations in tanks (1000l) and in Kiel Bight is compared with special references to mechanisms affecting species composition in spring and early summer. In a first experiment, three tanks filled with surface water just prior to the bloom (February 1983) were held under different light conditions. Exponential growth coincided with onset of the growth in the field. Growth in the two darkened tanks was retarded. In the field, a bloom of mainly Thalassiosira polychorda was observed, whereas in the light tank Thlassiosira 'pseudonana' and in the two darker tanks Skeletonema costatum were the domninant species. The observed shift in species compositions between tanks and in the field can be attributed partly to differences in growth strategies of species involved but also to the specific effect of population enclosure. In a second experiment (May/ June 1983) the influence of grazing pressure was studied in two tanks with different abundance of metazooplankton. Nauplii as well as large protozoans were grazed down more rapidly than the samller phytoflagellates, which confirmed earlier hypotheses based on field observations. After decline of grazers, possibly due to starvation, a succession from bacteria to nanoflagellates and then ciliates was observed.

Description: Long-term investigations of pore-water ammonium concentrations and sediment oxygen uptake were carried out in three different sediment types along a slope in Kiel Bight. The inverse relation between mineralization rates and ammonium concentrations at the three stations is explained by the differences in the role of various mechanisms transporting nutrients out of the sediments. Direct water exchange due to turbulent or density driven processes, bioturbation and pumping activity of benthic macrofauna and molecular diffusion are involved to various extents in nutrient fluxes out of the sediments studied. The role of different sediment types in the interaction with the pelagic system is discussed in a conceptual framework of pelagic system functioning in Kiel Bight.

Description: The publications of Matsuoka (1983) and Bujak (1984) on dinoflagellate cysts from the Neogene of Japan and the Paleogene‐Neogene of the Bering Sea‐northern North Pacific areas, respectively, resulted in the erection of two new species by each author which are synonymous. Impagidinium pacificum Bujak and Spiniferites ovatus Bujak are therefore designated junior synonyms of Impagidinium japonicum Matsuoka and Spiniferites hexatypicus Matsuoka. Another species, Spiniferites ovatus Matsuoka, does not occur in the material examined by Bujak. Specimens assigned by Matsuoka to Nematosphaeropsis labyrinthea and Tectatodinium pellitum are reassigned to Nematosphaeropsis lemniscata Bujak and Filisphaera filifera Bujak, respectively. The species Reticulatosphaera stellata Matsuoka, which Matsuoka designated the type species of his new genus Reticulatosphaera, is designated a subjective junior synonym of a species originally named by Benedek (1972) as Cleistosphaeridium actinocoronatum. C. actinocoronatum is transferred to Reticulatosphaera and becomes the type‐species of this genus. Specimens assigned to Areoligera senonensis Lejeune‐Carpentier sensu Gocht 1969 by Matsuoka (1974, 1983) and Tanyosphaeridium fusiform by Matsuoka (1974) are reattributed to Systematophora ancyrea and Distatodinium fusiforme (Matsuoka) comb, nov., respectively. Bujak also erected eight Eocene to Pleistocene concurrent‐range zones, two of which were named the I. pacificum and Spiniferites ovatus Zones. These are renamed the I. japonicum and 5. hexatypicus Zones, and the zonation is modified to extend the Trinovantedinium boreale Zone into the early Oligocene, and to restrict the S. hexatypicus Zone to the Miocene.

Description: Morphological characteristics of two large females of Haliphron atlanticus STEENSTRUP (= Alloposus mollis VERRILL) are described and illustrated. The soft and gelatinous body, the shape of the mantle aperture, the formation of the funnel and adhesive apparatus, and the straplike septa connecting the mantle and funnel and containing the stellate ganglion are characteristic features of the species. One specimen, weighing 41 kg after fixation, was found dead near Bergen (60°14′ N, 5°16′ E) in May 1983. The other, weighing 25 kg after being frozen, was caught alive at 210 m off Vestvägöy in the Lofoten archipelago (68°20′ N. 14°14′ E) in November 1984. It was possibly feeding on the prawn, Pandalus borealis KRøYER. Both specimens had arms partly missing and web torn, but were otherwise well preserved. Previous records of H. atlanticus are confined to tropical and warm-temperate areas. The present findings represent the first records from north of 42° N.

Description: This check-list is a compilation of the marine molluscs recorded from Norway and the abyssal depths of the Norwegian Sea. Molluscs not recorded from the Norwegian fauna but found on the North Sea plateau, the British North Sea coast, the Swedish west coast, and in Danish waters are also included. Distributional data are provided for each species. Most commonly used synonyms are listed, together with type species for each accepted generic name. Systematical code numbers are included for easy retrieval of information. An alphabetical index of all generic names mentioned concludes the check-list. Recent taxonomic alterations and all distributional records are documented by literature references.

Description: The feeding biology of the nectobenthic, sepiolid squid, Sepietta oweniana is treated based on behavioural observations in aquaria and stomach content analyses on 859 trawl caught squid. Juvenile squid in aquaria catch free-swimming prey, preferably the mysid Praunus flexuosus, day and night using the bottom only for shorter resting periods. Adult squid forage from dusk till dawn from positions close to the bottom and spend the day buried in the bottom. Praunus flexuosus is preferred as prey in comparison with demersal and benthic crustaceans as Palaemon elegans and Crangon crangon. Stomach analyses show that in daytime catches, only 16% of all analyzed specimens had stomach contents. Low frequencies were consistent throughout most sampled months in 1979 and 1982. Of the specimens with stomach contents most (50–100%) contained fragments of the euphausiid Meganyctiphanes norvegica. Specimens with remains of decapod shrimps were found in late spring and early summer. It is concluded that S. oweniana feeds in the hyperbenthic habitat at very low light intensities mostly on Meganyctiphanes norvegica in northern waters. A tentative ecological trade off explanation for this apparently inefficient feeding pattern is briefly discussed.

Description: Die Genese der Maare wird hauptsächlich an Beispielen aus der Eifel erläutert. Die Maarkessel sind durch phreato-magmatische Explosionen entstanden . Es werden die hydrologischen Voraussetzungen für diese Prozesse erörtert. Ob ein lavafördernder Vulkan oder ein Maar entsteht, hängt nicht von der Stellung zum Gewässernetz ab, sondern von Vorgängen im Magmenreservoir. Voraussetzung für die Entstehung von Maaren ist die Existenz von Tuffschloten. Wenn in solche Tuffschlote die Rinnsale kleinerer Täler hineinfließen, kommt es zu phreatischen Explosionen in geringer Tiefe (wohl nicht tiefer als 50 m). Dadurch bilden sich Sprengtrichter von wenigen Hundert m Durchmesser mit gleichmäßigen Tuffwällen. Größere Bäche oder Flüsse können tiefer in die Tuffschlote hinabfließen, so daß erst in etwa 300-500 m Tiefe die Explosionen ausgelöst werden. Da in diesem Fall mehr Wasser mit mehr heißem Gestein in Berührung kommt, werden die Explosionen heftiger, können aber keinen Trichter nach oben durchbrechen. Das in der Explosionskammer zertrümmerte Gestein wird durch enge Kanäle in mehreren Strahlen hinausgepreßt, so daß kilometerweite schmale Tuffbahnen entstehen. In den durch die Dampfexplosion erzeugten Hohlraum brechen große Schollen aus dem Dach ein. Es kann durch die Explosionen ein Sog den Schlot hinab entstehen, der sich in große Tiefen fortpfanzt, so daß ultrabasische Gesteine mit nach oben gerissen werden (Meerfelder Maar und Dreiltt Weiher in der Eifel). Das Grundwasser im Schiefergebirge dürfte nicht ausreichen, um phrealilchc Explosionen zu erzeugen. Die Tuffschlote und damit auch die Maare haben innerhalb der Vulkanfelder eine Randposition, die lavafördernden Vulkane herrschen dagegen in den Zentren vor; das läßt sich außer in der Westeifel auch deutlich an der Chaine des Puys in der Auvergne zeigen.