ALBERT

Beschreibung: The dynamics of accretionary convergent margins are severely influenced by intense deformation and fluid expulsion. To quantify the fluid pressure and fluid flow velocities in the Hellenic subduction system, we set up 2-D hydrogeological numerical models following two seismic reflection lines across the Mediterranean Ridge. These profiles bracket the along-strike variation in wedge geometry: moderate compression and a 〉4 km thick underthrust sequence in the west versus enhanced compression and 〈1 km of downgoing sediment in the center. Input parameters were obtained from preexisting geophysical data, drill cores, and new geotechnical laboratory experiments. A permeability-porosity relationship was determined by a sensitivity analysis, indicating that porosity and intrinsic permeability are small. This hampers the expulsion of fluids and leads to the build up of fluid overpressure in the deeper portion of the wedge and in the underthrust sediment. The loci of maximum fluid pressure are mainly controlled by the compactional fluid source, which generally decreases toward the backstop. However, pore pressure is still high at the decollement level at distances 〈100 km from the deformation front, either by the incorporation of low permeability evaporites or additional compaction of the wedge sediments in the two profiles. In the west, however, formation of a wide accretionary complex is facilitated by high pore pressure zones. When compared to other large accretionary complexes such as Nankai or Barbados, our results not only show broad similarities but also that near-lithostatic pore pressures may be easier to maintain in the Hellenic Arc because of accentuated collision, some underthrust evaporates, and a thicker underthrust sequence.

Beschreibung: This study presents aspects of the spatial and temporal variability of abyssal water masses in the Ionian Sea, as derived from recent temperature, salinity, dissolved oxygen and velocity observations and from comparisons between these and former observations. Previous studies showed how in the Southern Adriatic Sea the Adriatic Deep Water (AdDW) became fresher (ΔS ≈ −0.08) and colder (ΔT ≈ −0.1°C) after experiencing warming and salinification between 2003 and 2007. Our data, collected from October 2009 to July 2010 from two bottom moorings, one within the Strait of Otranto and the other in the northern Ionian, confirm this tendency: a bottom vein of southward-flowing AdDW, whose temperature and salinity continuously decreased during the observation time, was detected there. Typically, the vein travel time between the two stations ranged between 45 and 50 days. This gave us a temporal estimate for AdDW anomaly propagation towards the Ionian abyss from their Adriatic generation region. The density excess of the observed vein was always enough to enable its existence as a bottom-arrested current. This evidence confirms that, at that time (2009 and 2010), the Adriatic Sea was greatly contributing to the formation of Eastern Mediterranean Deep Water (EMDW), the bottom water of the Eastern Mediterranean. Hence, based on these results and on the evidence that, from 2003 to 2009, abyssal Ionian waters became saltier and warmer under the time-lagged influence of AdDW, possible future changes in the EMDW characteristics, as a response to Adriatic variability, are discussed.

Beschreibung: El Niño–Southern Oscillation (ENSO) in the Pacific and the analogous Atlantic Niño mode are generated by processes involving coupled ocean–atmosphere interactions known as the Bjerknes feedback. It has been argued that the Atlantic Niño mode is more strongly damped than ENSO, which is presumed to be closer to neutrally stable. In this study the stability of ENSO and the Atlantic Niño mode is compared via an analysis of the Bjerknes stability index. This index is based on recharge oscillator theory and can be interpreted as the growth rate for coupled modes of ocean–atmosphere variability. Using observational data, an ocean reanalysis product, and output from an ocean general circulation model, the individual terms of the Bjerknes index are calculated for the first time for the Atlantic and then compared to results for the Pacific. Positive thermocline feedbacks in response to wind stress forcing favor anomaly growth in both basins, but they are twice as large in the Pacific compared to the Atlantic. Thermocline feedback is related to the fetch of the zonal winds, which is much greater in the equatorial Pacific than in the equatorial Atlantic due to larger basin size. Negative feedbacks are dominated by thermal damping of sea surface temperature anomalies in both basins. Overall, it is found that both ENSO and the Atlantic Niño mode are damped oscillators, but the Atlantic is more strongly damped than the Pacific primarily because of the weaker thermocline feedback.

Beschreibung: A monthly, isopycnal/mixed-layer ocean climatology (MIMOC), global from 0 to 1950 dbar, is compared with other monthly ocean climatologies. All available quality-controlled profiles of temperature (T) and salinity (S) versus pressure (P) collected by conductivity-temperature-depth (CTD) instruments from the Argo Program, Ice-Tethered Profilers, and archived in the World Ocean Database are used. MIMOC provides maps of mixed layer properties (conservative temperature, Θ, absolute salinity, SA, and maximum P) as well as maps of interior ocean properties (Θ, SA, and P) to 1950 dbar on isopycnal surfaces. A third product merges the two onto a pressure grid spanning the upper 1950 dbar, adding more familiar potential temperature (θ) and practical salinity (S) maps. All maps are at monthly 0.5° × 0.5° resolution, spanning from 80°S to 90°N. Objective mapping routines used and described here incorporate an isobath-following component using a “Fast Marching” algorithm, as well as front-sharpening components in both the mixed layer and on interior isopycnals. Recent data are emphasized in the mapping. The goal is to compute a climatology that looks as much as possible like synoptic surveys sampled circa 2007–2011 during all phases of the seasonal cycle, minimizing transient eddy and wave signatures. MIMOC preserves a surface mixed layer, minimizes both diapycnal and isopycnal smoothing of θ-S, as well as preserves density structure in the vertical (pycnoclines and pycnostads) and the horizontal (fronts and their associated currents). It is statically stable and resolves water mass features, fronts, and currents with a high level of detail and fidelity.

Beschreibung: Four major NE trending postglacial volcanic and tectonic fissure swarms (volcanic systems) occur on the Reykjanes Peninsula, and the westernmost three are the main subject of this paper. Two main types of basaltic volcanoes are associated with these systems: shields of picrite and olivine tholeiite and tholeiite fissures. The average volume of 26 shields is 1.11 km3, and the total production is 29 km3, whereas the corresponding figures for lavas from 101 volcanic fissures are 0.11 km3 and 11 km3. The tectonic fractures are either tension fractures or normal faults of widths up to 20 m, throws up to 10 m, and lengths up to several kilometers. The volcanism and tectonics can be explained by magmatic pressure changes in ellipsoidal magma reservoirs located beneath the fissure swarms. A magmatic pressure increase of the order of 10 MPa is found to be sufficient for an excess uplift of the order of several meters, which is all that is needed to account for the fractures and measured dilation in the fissure swarms. It is concluded that most shield volcanoes, in particular the picrite shields and the large olivine tholeiite shields, formed during the early postglacial period and that their formation was facilitated by the stress field generated as a result of rapid uplift and bending of the crust above the reservoirs. Since that time the reservoirs have become independent systems, the volcanism has been confined to fissures, and the production rate has decreased significantly. During typical fissure eruptions (0.015 km3), only the uppermost several hundred meters of the source reservoir, depending on its magma content, supply magma to the eruption.

Beschreibung: The Denmark Strait overflow provides about half of the total dense water overflow from the Nordic Seas into the North Atlantic Ocean. The velocity of the overflow has been monitored in the Strait with two moored Acoustic Doppler Current Profilers since 1996 with several interruptions due to mooring losses or instrument failure. So far, overflow transports were only calculated when data from both moorings were available. In this work, we introduce a linear model to fill gaps in the time series when data from only one instrument is available. The mean overflow transport is 3.4 Sv and exhibits a variance of 2.0 Sv2. No significant trend was detected in the time series. The highest variability in the transport is associated with the passage of mesoscale eddies with time scales of 2–10 days (associated with a variance of 1.5 Sv2). Seasonal variability is weak and explains less than 5% of the variance in all time series, which is in contrast to the strong seasonal cycle found in high resolution model simulations. Interannual variability is on the order of 10% of the mean. A relation to atmospheric forcing such as the local wind stress curl, as well as to larger scale phenomena, e.g. the North Atlantic Oscillation, is not detected. Since 2005 data from moored temperature, conductivity and pressure recorders have been available as well, monitoring the hydrographic variability at the bottom of Denmark Strait. In recent years the temperature time series of the Denmark Strait overflow revealed a cooling, while the salinity stayed nearly constant.

Beschreibung: Large-scale budget calculations and numerical model process studies suggest that lateral eddy heat fluxes have an important cooling effect on the Norwegian Atlantic Current (NwAC) as it flows through the Nordic Seas. But observational estimates of such fluxes have been lacking. Here, wintertime surface eddy heat fluxes in the eastern Nordic Seas are estimated from surface drifter data, satellite data and an eddy-permitting numerical model. Maps of the eddy heat flux divergence suggest advective cooling along the path of the NwAC. Integrating the flux divergence over temperature classes yields consistent estimates for the three data sets; the waters warmer than about 6°C are cooled while the cooler waters are warmed. Similar integrations over bottom depth classes show that regions shallower than about 2000 m are cooled while deeper regions are warmed. Finally, integrating the flux divergence along the core of the NwAC suggests that the highest eddy-induced heat loss at the surface is along the steepest part of the continental slope, east of the Lofoten Basin. The model fields indicate that cooling of the current by lateral eddy fluxes is comparable to or larger than the local heat loss to the atmosphere.

Beschreibung: On 12 September 2007, an Mw8.4 earthquake occurred within the southern section of the Mentawai segment of the Sumatra subduction zone, where the subduction thrust had previously ruptured in 1833 and 1797. Traveltime data obtained from a temporary local seismic network, deployed between December 2007 and October 2008 to record the aftershocks of the 2007 event, was used to determine two-dimensional (2-D) and three-dimensional (3-D) velocity models of the Mentawai segment. The seismicity distribution reveals significant activity along the subduction interface and within two clusters in the overriding plate either side of the forearc basin. The downgoing slab is clearly distinguished by a dipping region of highVp (8.0 km/s), which can be a traced to ∼50 km depth, with an increased Vp/Vs ratio (1.75 to 1.90) beneath the islands and the western side of the forearc basin, suggesting hydrated oceanic crust. Above the slab, a shallow continental Moho of less than 30 km depth can be inferred, suggesting that the intersection of the continental mantle with the subducting slab is much shallower than the downdip limit of the seismogenic zone despite localized serpentinization being present at the toe of the mantle wedge. The outer arc islands are characterized by low Vp (4.5–5.8 km/s) and high Vp/Vs (greater than 2.0), suggesting that they consist of fluid saturated sediments. The very low rigidity of the outer forearc contributed to the slow rupture of the Mw 7.7 Mentawai tsunami earthquake on 25 October 2010.

Beschreibung: The spatial distribution of some major and trace element and isotopic characteristics of backarc Plio-Quaternary basaltic to high-Mg andesitic (51% to 58% SiO2) lavas in the southern Puna (24°S to 27°S) of the Central Andean Volcanic Zone (CVZ) reflect varying continental lithospheric thickness and the thermal state of the underlying mantle wedge and subducting plate. These lavas erupted from small cones and fissures associated with faults related to a change in the regional stress system in the southern Puna at ≈ 2 to 3 Ma. Three geochemical groups are recognized: (1) a relatively high volume intraplate group (high K; La/Ta ratio 〈25) that occurs over a thin continental lithosphere above a gap in the modern seismic zone and represents the highest percentage of mantle partial melt, (2) an intermediate volume, high-K calc-alkaline group ( La/Ta ratio 〉25) that occurs over intermediate thickness lithosphere on the margins of the seismic gap and behind the main CVZ and represents an intermediate percentage of mantle partial melt, and (3) a small-volume shoshonitic group (very high K) that occurs over relatively thick continental lithosphere in the northeast Puna and Altiplano and represents a very small percentage of mantle partial melt. Mantle-generated characteristics of these lavas are partially overprinted by mixing with melts of the overlying thickened crust as shown by the presence of quartz and feldspar xenocrysts, negative Eu anomalies (Eu/Eu 〈 0.90; most 〈 0.80), and radiogenic Sr (〉 0.7055) and Pb and nonradiogenic Nd ( εNd 〈 −0.4) isotopic ratios. Mixing calculations show that the lavas generally contain more than 20% to 25% crustal melt. The eruption of the intraplate group mafic lavas, the change in regional stress orientation, and the high elevation of the southern Puna are suggested to be the result of the late Pliocene mechanical delamination of a block (or blocks) of continental lithosphere (mantle and possibly lowermost crust). The loss of this lithosphere resulted in an influx of asthenosphere that caused heating of the subducting slab and yielded intraplate basic magmas that produced extensive melting at the base of the thickened crust. Heating of the subducting slab led to formation of the seismic gap and trenchward depletion of the slab component. Backarc calc-alkaline group lavas erupted on the margins of this delaminated block, whereas shoshonitic group lavas erupted over a zone of relatively thick nondelaminated lithosphere to the north.

Beschreibung: New charts of bathymetry, acoustic character, and sediment distribution describe the Hess Rise, a large oceanic plateau in the central north Pacific. Discrete physiographic provinces on the Hess Rise are the High Plateau, shallower than 3900 m, trending N30°W; the Northeastern Flank, a smooth, gentle slope gradually increasing in depth to the northeast; the Woollard Abyssal Plain, extending farther to the northeast; the Volcanic Province with its high peaks and ridges along the southern margin of the Hess Rise; the Mendocino Fracture Zone to the south, expressed by broad, planar seafloor regions bordered by ridges and scarps; the Western Steps, formed by structural benches on the western side of the Rise; and the Emperor Deep, between the rise and the Emperor Seamounts. Five types of acoustic units have been mapped and interpreted: a transparent layer, predominantly of biosiliceous pelagic clay; a stratified layer, predominantly of nannofossil ooze; a diffuse layer of debris flows that seem to have originated mostly in the Volcanic Province; an opaque horizon commonly formed of volcaniclastic sediments that are usually found on the seafloor of the Mendocino Fracture Zone; and a hyperbolic horizon, indicating outcrops of igneous rock. The pronounced effect of bottom currents on the present-day environment of deposition in the Hess Rise is evidenced by the presence of the opaque horizon, which is interpreted as an erosion surface, and by current moating, abrupt thinning of surface layers and truncation of subbottom reflectors. The widespread erosion on the seafloor of the Mendocino Fracture Zone is attributed to the flow of Antarctic bottom water.

Beschreibung: We present a conceptual model of fluid circulation in a ridge flank hydrothermal system, the Mariana Mounds. The model is based on chemical data from pore waters extracted from piston cores and from push cores collected by deep‐sea research vessel Alvin in small, meter‐sized mounds situated on a local topographic high. These mounds are located within a region of heat flow exceeding that calculated from a conductive model and are zones of strong pore water upflow. We have interpreted the chemical data with time‐dependent transport‐reaction models to estimate pore water velocities. In the mounds themselves pore water velocities reach several meters per year to kilometers per year. Within about 100 m from these zones of focused upflow velocities decrease to several centimeters per year up to tens of centimeters per year. A larger area of low heat flow surrounds these heat flow and topographic highs, with upwelling pore water velocities less than 2 cm/yr. In some nearby cores, downwelling of bottom seawater is evident but at speeds less than 2 cm/yr. Downwelling through the sediments appears to be a minor source of seawater recharge to the basaltic basement. We conclude that the principal source of seawater recharge to basement is where basement outcrops exist, most likely a scarp about 2–4 km to the east and southeast of the study area.

Beschreibung: Precipitation downscaling improves the coarse resolution and poor representation of precipitation in global climate models and helps end users to assess the likely hydrological impacts of climate change. This paper integrates perspectives from meteorologists, climatologists, statisticians, and hydrologists to identify generic end user (in particular, impact modeler) needs and to discuss downscaling capabilities and gaps. End users need a reliable representation of precipitation intensities and temporal and spatial variability, as well as physical consistency, independent of region and season. In addition to presenting dynamical downscaling, we review perfect prognosis statistical downscaling, model output statistics, and weather generators, focusing on recent developments to improve the representation of space-time variability. Furthermore, evaluation techniques to assess downscaling skill are presented. Downscaling adds considerable value to projections from global climate models. Remaining gaps are uncertainties arising from sparse data; representation of extreme summer precipitation, subdaily precipitation, and full precipitation fields on fine scales; capturing changes in small-scale processes and their feedback on large scales; and errors inherited from the driving global climate model.

Beschreibung: Retrievals of aerosol optical depth (AOD) from MODIS, and of sea surface temperature (SST) from TMI are analyzed jointly with the output of a numerical model for the period 2000-2006 to determine the impact of Saharan dust on the eastern subtropical North Atlantic SST. Simultaneously with, or shortly after strong dust outbreaks, a decrease in SST of 0.2 degrees to 0.4 degrees C can be observed in the microwave SST data set, which is consistent with an independent estimate of SST decrease simulated here by a local mixed layer model. However, low wind conditions and a shallow mixed layer are required to reach this response, and it is therefore unlikely that a clear response of SST to dust lasting more than a few days can be seen in the microwave SST observations. An inspection of microwave SST observations suggests that about 30% of SST variance could be explained by dust-induced cooling in our study region that is not represented in existing AVHRR SST fields nor represented in reanalysis centers-provided surface heat fluxes. On longer time scales, a comparison between observed SST fields and simulated SST, using an eddy-permitting model of the North Atlantic, suggests a cooling of about 0.5 degrees C on the local SST on sub-seasonal to interannual time scales which is significantly correlated and consistent with a dust-induced cooling. However, while supportive of the hypothesis that Saharan dust lead to a reduction in SST, the eddy-resolving model results are not by themselves conclusive. Moreover, the effects of dust-induced cooling on simulations of the ocean circulation, on atmospheric forecasts and on climate simulations remains to be investigated in future studies.

Beschreibung: Helium isotope measurements in six major basins in the Gulf of California show that the deep Guaymas Basin has 3He/4He 65–70% higher than atmospheric helium, clear evidence of mantle helium injection. Smaller 3He excesses observed in the Carmen and Farallon basins may be derived from this Guaymas Basin anomaly. The 3He concentrations in the Mazatlan Basin in the mouth of the Gulf of California are similar to average eastern Pacific values, indicating that the Gulf does not provide a significant flux of 3He into the general Pacific circulation. On the basis of temperature and salinity measurements an upper limit of 0.28°C can be placed on the amount of geothermal heating observed in any of the basins. The isotopic ratio of the injected Guaymas Basin helium is found to be 3He/4He = (1.10±0.06) × 10−5, almost identical to the helium signature observed at the Galapagos Rift but somewhat lower than the average ratio in oceanic basalt glasses.

Beschreibung: Fifty-four new heat flow measurements in the central troughs of the Guaymas basin support the hypothesis that they are sites of active intrusion. In the northern trough a distinct pattern of hydrothermal cooling is revealed, with venting along the western boundary fault of the trough. In the southern trough an analogous pattern is apparently superimposed upon a conductive cooling anomaly associated with a recent central intrusion. The discharge of thermal waters occurs along the boundary faults and through other faults associated with a possible horst block located in the north central floor of the southern trough. The heat flow patterns suggest that the intrusions are episodic and do not occur simultaneously along the length (15–40 km) of a spreading segment. A review of all available heat flow measurements for the Guaymas basin suggests that most of the recharge for a pervasive regional hydrothermal system is limited to the central depressions, with perhaps some contribution from pore water. The discharge of thermal waters occurs predominantly in the central depressions and possibly along the boundary transform faults and fracture zones. The regions of the basin more than a few kilometers in distance from the spreading axis, although presumably underlain by a hydrothermal system, are probably not the location of numerous vents or recharge zones.

Beschreibung: Studies of the last 125 million years of oceanographic and climatic history have benefited greatly from the impetus provided by the Deep Sea Drilling Project. Knowledge of the sedimentary and paleontologic record of the major ocean basins, in conjunction with study of pelagic marine sections exposed on land, has permitted both the testing of old and the development of new hypotheses to explain local and global ocean chemical, sedimentologic and biotic events. Some of the more striking and topical problems in paleoceanography are the oceanic “anoxic events” of early to middle Cretaceous age, the biotic crisis at the Cretaceous/Tertiary boundary, the Eocene/Oligocene extinctions and climatic and circulation events, the Messinian “salinity crisis” (late Miocene) and its effects on the world ocean, and Pleistocene glacial cycles and paleoceanography. Possible explanations of these events, which have been proposed over the last five years, are reviewed in this paper.

Beschreibung: Projekte: a) Erosionsbeobachtung im Bereich der Veisnäs-Rinne b) Geräteerprobungen für die Reise JASIN

Beschreibung: The intention was to study recruitment of benthic macrofauna to an exposed shore. Two mesh-sizes (1.0 and 0.5 mm) were used. The additional abundance and biomass in the finer sieve show both temporal and spatial variations. Maximum values were found in the autumn and at the shallowest station (5 m). The reasons for this are discussed.

Beschreibung: In 1975 and 1976 at two stations in the Arkana and the Bornholm Sea the dynamics of the plankton development were studied. The annual course of the measured biological parameters shows peaks of phytoplankton productivity in spring and summer, and of zooplankton in summer. In spring also the phytoplankton biomass reaches a maximum while in August only low chlorophyll values could be observed. In summertime the pelagic system is characterized by an equilibrium state. In autumn after a possible autumnal bloom of phytoplankton all biological parameters sink down to a winter level.

Beschreibung: Nitrogen fixation measurements carried out in 1974 and 1975 in the Baltic Sea showed that heterocyst fixed nitrogen c. 3.5 pg (2)-1. According to our preliminary calculations the amount of nitrogen fixed in 1974 in the northern and central Baltic proper was c. 100000 tons.

Beschreibung: In 1970/1971 zooplankton was collected monthly at 33 stations in Kiel Bay by means of a Bongo net equipped with 300 µm gauze. Adult copepods were separated into species and sexes. Eleven species were found of which seven were dominant. A succession between winter-spring species (Temora longicornis, Pseudocalanus sp., Acartia bifilosa) and summer-fall species (Centropages hamatus, Paracalanus parvus, Acartia longiremis, A. tonsa) took place. Total abundance varied considerably between the stations. Usually female copepods were more frequent than mal es (up to 85%), with the exceptions of Temora longicornis and Centropages hamatus, which showed a sex ratio of about 1: 1. The sex ratios of Acartia bifilosa and A. longiremis were related to the concentration of the population.

Beschreibung: Solutions of detergent or crude oil of 10 ppm, 50 ppm, and 100 ppm after 48-96 hours of exposure induce significant changes in the ionic composition of the hemolymph of the shrimp Crangon crangon and the crab Rhithropanopeus harrisi. The concentrations of sodium, calcium, and chloride ions decrease, whereas the concentration of potassium increases in both species exposed to both pollutants. - The magnesium ion concentration decreases in the hemolymph of the shrimp incubated in solutions of detergent and in the crab incubated in the water containing crude oil. - lt is suggested that changes of the ionic composition of the hemolymph of the studied shrimps and crabs under influence of both pollutants are possibly brought about by alteration of cell membrane permeability and action on some enzyme activities.

Beschreibung: The filtration, feeding and assimilation rates of the zooplankton consisting largely of copepods in a shallow eutrophic bodden south of the Darß-Zingst Peninsula (salinity: 5-7‰) were determined under field conditions with the help of 14 C-labelled phytoplankton. During the zooplankton maximum in May (biomass: 2.13 mg dry weight/l), the feeding rate was up to 53.63% of the primary production. The zooplankton production calculated from the experimentally determined assimilation rates was not more than 6.5% of the primary production. The continuously available substantial amounts of detritus resulted in an extraordinarily low grazing rate. 0.39-3.63% of the seston present were removed from the water body daily by filtration. The studies show that the zooplankton also plays an important role in the ecosystem, at least part of the time, even in severely eutrophic landlocked coastal waters.

Beschreibung: Kassari Bay is of a specific character, a relatively isolated, sheltered and shallow sea area where the sediment mainly consists of clay and sandy clay. The main communities are the association of the loose-lying red algae Furcellaria fastigiata and Phyllophora brodiaei f. angustissima and the association Zosteretum marinae and its variant which is rich in red algae. Areas with dense vegetation alternate with areas almost without vegetation, or where only single tufts of red algae or some charophytes and phanerogames are found. The floristic list contains 24 taxa, 5 of them are phanerogames. Sphacelaria radicans is a new taxon for the Estonian flora.

Beschreibung: Subject of the experimental investigations are the effects of chronic toxicity exerted by the following pollutants of industrial origin on some animals from the Bay of Gdańsk: 1. phosphogypsum; 2. some detergents, i.e. a commercial product "SOLO", a mixture of nonionic and anionic surfactants (for household purposes), and an oil-spill remover Gamlen "CW" Solvent; 3. crude Kuwait oil and one of its derivatives, the fuel oil No. III. -The experimental animals are: Crangon crangon L., Rhithropanopeus harrisi (Gould), the crucial carp (Carassius carassius L.), the pike (Esox lucius L.) and the perch (Perca fluviatilis L.). Beside these inhabitants of the Bay of Gdańsk, also carp fry is used in one of the experiments. -The pollutants mentioned above induce sublethal changes in: the enzymic system, the reproductive activity, embryonic and larval development. Additionally, degenerative changes in the ultrastructure of crustacean brain and pathological disturbances in function and structure of isolated mitochondria could be observed. The general conclusion is that chronic sublethal toxicity may severely affect or even destroy some marine ecosystems.

Beschreibung: A 30 sample unit soft-bottom monitoring station was compared to corresponding 5 sample unit stations in the Åland archipelago in the northern Baltic Sea. The samples of macrozoobenthos were taken with an Ekman-Birge bottom-sampler (0.03 m2). The dynamics of the species populations were tested by analysis of variance during a period from 1972-1975 at the five-unit stations. Most of the differences in the mean densities were not verified. Estimation of a minimum sample size was made for the species at the 30 unit station. The spatial distribution of Macoma balthica makes it a species that is easy to sample. lts estimated minimum number of samples units needed for recording a 50 % change in population desity is nine. The other species require a larger number of sample units. The results show the low level of precision when measuring gradual changes of the benthic assemblages using a sample size of five units on soft bottom macrofauna.

Beschreibung: In coastal areas or estuaries cadmium-contents of water and sediments may be distinctly increased. The acute toxicity of Cd to sensitive organisms is strongly modified by environmental factor combinations occuring in the Baltic. This could be demonstrated with hydroid polyps. In comparison with other species and developmental stages, up to the present, Laomedea loveni proved to be the most sensitive test species to Cd. Within the ecological range the sensitivity to Cd inceases with higher temperatures and lower salinities. At these conditions not only the rate of accumulation of Cd is enhanced, but the protoplasmic sensitivity is increased to internal metal concentration. In longterm experiments with Clava multicornis the modifying effect of temperature and salinity decreases during the course of some weeks. - Contrary to cnidarians, many molluscs are able to accumulate high concentrations of Cd without signs of physiological damage. In many places of the Western Baltic the levels of Cd in Mytilus edulis are higher than in comparable individuals from localities of the North Sea coast. There are also correlations of Cd-contents of mussels with depth of their locality, size and season. Of the mussel's organs especially digestive diverticula and kidney accumulate the metal. Preliminary results with ion exchange - and gel filtration chromatography of the mussel's proteins suggest the occurence of special Cd-binding proteins, e.g. in the hepatopancreas, as a main reason for the high tolerance of M. edulis to cadmium.

Beschreibung: This pilot study was carried out to determine the duration of exposure time taking into account the complex interactions in the ecosystem and to test the aptitude of artificial hard substrates as far as surface-texture, size and shape of the substrates are concerned. In depths of 10.0 and 20.0 m concrete tubes 1.0 m long and 0.5 m in diameter were exposed for four years. Colonization was observed by scientific divers and recorded by photography.

Beschreibung: A coralline alga from the Baltic (Belt Sea, Samsö) belonging to the genus Phymatolithon has been investigated. The mineral skeleton consists of magnesium calcite and shows the following composition (expressed in percent of the dry weight): 94-96% skeletal carbonates, 4-6% organic matter, 32.1-33.4% Ca, 3.3-3.5% Mg and 0.15-0.17% Sr. MgC03 determined by the peak shift method (X-ray diffraction) is in the region of 10-11 mol % . The kinetics of 45Ca uptake consist of a fast step and a low step. The fast step is due to equilibration of isotope with the soft tissues and spaces between cells. The slow step is attributed to net deposition of calcium in the skeleton. From the rate constant of the slow step calcium net deposition was found to be 5.6 1 μg Ca/g dry weight/h or 14 μg CaC03/g dry weight/h. Pulse chase experiments show that the calcification is the resultant of calcium exchange between the alga and the seawater. Light-dark calcification ratios are in the range of 1.1-1.3. The O2 production amounts to 0.04 mg 02/g dry weight/h at an irradiance of 0.085 KW/m2. When expressed per unit weight of total organic matter, this assimilation rate would fall into the range commonly found for other noncalcifying Rhodophyta. The results form the basis for further work on calcification mechanism and CaC03 production in coralline algae.

Beschreibung: Using the mean annual variations in temperature and oxygen content at ten stations in all parts of the open Baltic proper, relations between phytoplankton spring bloom and maximum oxygen content in the near-surface layer are pointed out. By means of the calculated times of the oxygen maxima and the observed times of the spring blooms, regional peculiarities of the three fundamental areas of the Baltic proper - Arkona Sea, Bornholm Sea and Gotland Sea - are explained. - The results show that there is a clear connection between phytoplankton spring bloom and maximum oxygen content. Furthermore, the longer the phase lag between oxygen maximum and temperature minimum, the longer the period of higher oxygen content in spring.

Beschreibung: Nitrogen (C2H4)-fixation in planktic heterocystous blue-green algae was measured in the Askö area throughout the summer 1976. -Temporal variations in total number of heterocysts, heterocyst frequency, heterocyst activity, acetylene reduction and primary production are discussed. - The amount of nitrogen fixed is estimated to 0.6 gN/m2 x year.

Beschreibung: The level of oxygen consumption of a Baltic population of Mesidothea entomon was determined in salinities of 1,6.5 and 15‰ and at temperatures of 5°C and 15°C using males, ovigerous females and non-ovigerous females. No significant dependence was found between respiration and salinity. The mean oxygen consumption is of the same order of magnitude as or Baltic marine isopods in general. lt decreases towards the autumn. The oxygen consumption remains at the same level independent of the oxygen concentration in the water until this falls below 2 mg per litre.

Beschreibung: The macrofauna of the red algal zone of Kiel Bay is quantitatively investigated for the first time. 109 species were found of which 68 can be considered as genuine inhabitants of the phytal zone. The classification of the phytal fauna according to locomotory and feeding type, their abundance and biomass relative to water depth and their value as fish food were investigated in more detail.

Beschreibung: The Baltic Sea is one of the largest brackish water areas in the world, and osmotic stress has severely reduced the number of species in its benthic macro-and meiofauna. This leads to an almost uniquety simple benthic ecosystem. - The benthic macrofauna shows a steep north to south increase in biomass, from mean values of about 1 gm-2 wet weight in the Bothnian Bay, to over 100gm-2 above the halocline in the northern Baltic proper, and even higher values in the southwestern Baltic. Meiofauna biomass is much less variable, and increases only from about 2 gm-2 wet weight to about 6 gm-2 along the same gradient. There is also a north-south gradient in phytoplankton primary production, with an increase by a factor of about 3 to 6. Very low salinities (2-3‰S) exclude filter-feeding bivalves from most of the Bothnian Bay, explaining in part the extremely low biomasses in the north. When filter-feeders are substracted, the benthos-feeding macrofauna biomass still increases more from north to south than the primary production, while the meiofauna biomass, on the other hand' increases less. Calculations are presented which indicate that the total resource use by benthos-feeding macro + meiofauna increases rounghly in proportion to the primary production. The observed shift in dominance from meiofauna to macrofauna is attributed to meiofauna being competitively superior in low food environments (Bothnian Bay), while in richer environments predation by macrofauna limits meiofauna populations (Bothnian Sea, Baltic proper). -Most of the Baltic shows strong salinity stratification, with little or no oxygen present below the primary halocline. This leads to an oxygen-dependent zonation of the fauna, with macrofauna disappearing at higher oxygen levels than some of the meiofauna. Nematodes in low numbers persist even in areas which have been anoxic for long periods. -The secondary productivity of the widely distributed Pontoporeia community is described, and it is concluded that the Pontoporeia populations are primarily food limited, and that the benthic system is intimately coupled to the pelagic system, and may respond to events in the plankton within weeks. -Attempts to estimate the energy flow through the benthos of the Askö-Landort area (N. Baltic proper) indicate that 40 -60gCm to fuel the benthos. - Finally, direct interactions between macro- and meiofauna are discussed. The evidence for control of meiofauna populations by macrofauna predation is suggestive, but not yet conclusive. Examples are also given of more positive interactions between macro- and meiofauna, and it is proposed that a proper balance between different size classes of benthos may be necessary for efficient remineralization.

Beschreibung: In summer the effects of ferry traffic in the southern Åland archipelago on animal number and biomass is less pronounced in the Fucus zone than in the Cladophora zone. - In the autumn the combined effects of wave action and low temperature are shown to cause a differentiated effect in exposed and unexposed sites, the number of macroscopic animals beeing reduced at an earlier stage in the former. On a qualitative basis Gammarus sp. and ldotea baltica in addition to Mytilus edulis best endure the mechanical stress induced.

Beschreibung: Dynamics of Baltic ecosystems and causes of their variability are discussed and special attention is paid to the use of ecological models as a tool for research and management. - The causes of the observed changes in salinity, temperature, and oxygen of the deep water of the Baltic Sea are reviewed and discussed. - The work has led to the formulation of a hypothesis by which it appears possible to explain the oxygen development and the long-term development of other hydrographic components. The analyses indicate that the change of the level of the interface from - 80 m at the beginning of the century to about - 60 m today has increased the quantity of dead organic matter sinking down through the halocline as a consequence of the increased area of contact between the surface water and the deep water. The increased contact area has led to a corresponding increase in all fluxes through the halocline driven by turbulent gradient diffusion including an increase in the upward flux of nutrients. This has led to a fertilization of the surface water which has increased organic production in the surface zone. This in turn increases the amount of dead organic matter supplied to the deep water. At the same time the temperature increase has increased the rate of oxygen consumption. The net result is that oxygen in the deep water is being consumed at a much higher rate today than previously. lt is estimated that the rate of consumption has increased about 110% since the end of the last century. This implies an increase in the primary production of about 40%. - The supply of oxygen to the deep water has increased primarily as a consequence of the increase in the area of contact between the surface water and the deep water, and secondly as a consequence of an increase in the vertical oxygen concentration gradient. However, the rate of increase of supply has been smaller than the rate of increase of the consumption. The relative difference between the consumption and the supply has increased from 0 at equilibrium conditions at the end of the last century to about 10% today. Although this change in the balance between supply and consumption appears to be marginal, it is nevertheless sufficient to bring about the dramatic decrease of the oxygen concentration in the deep water from about 3 ml/l at the end of the last century to close to O ml/l today. - The model introduced represents a preliminary step towards a Baltic model, which necessarily must take the changing position of the halocline and related effects into account.

Beschreibung: The study describes the results of zooplankton sampling during a short period of the International Baltic Year at station F 81 (BY 15 A) in the Gotland Deep. An analysis has been made of the abundance at different depths of the commonest species belonging to the groups: Copepoda, Cladocera, Rotifera, and "others". A clear diurnal pattern could be distinguished mainly for the copepods, which were strongly dominant. Their vertical distribution showed both interspecific differences and intraspecific differences between developmental stages. The cladocerans were still very rare at that time of the summer, their numbers being too low for any definite conclusions.

Beschreibung: In the individual parts of the Baltic Sea the vernal bloom of phytoplankton starts at different times. An attempt is made to explain these temporal differences by means of the hydrographical differences of the regions. lt is shown that in the western Baltic and in coastal areas the start of the bloom depends on the increasing radiation when sufficient nutrients are available. In the deeper parts of the Baltic, however, the reduction of the vertical convection together with sufficient light and nutrient supplies is the necessary condition for the outburst of phytoplankton. This lessening of vertical convection is indicated by a decrease of the ratio depth of mixed layer to depth of euphotic zone. The mass development, that means the rapid growth of phytoplankton biomass, is possible when the mixed layer tends to be equal to or less than the euphotic layer. For this thesis examples from different regions of the Baltic and of the North Sea are given.

Beschreibung: Phallodrilus monospermathecus, a typical interstitial oligochaete from Baltic and North Sea beaches, shows a characteristic microdistribution preferring the moist layers usually slightly above ground water which are sufficiently supplied with water and oxygen, protected against wave action and devoid of hydrogen sulfide. - Ecophysiological experiments testing the resistance against temperature, salinity, alcalinity, and hypoxia proved the populations to be extremely euryecous tolerating single factors far beyond their natural range. However, combinations of adverse factors reduced the tolerable limits, especially those of salinity, considerably. - In boreal climate, the habitat fluctuations for many physiographical factors apparently lie well within the tolerable range of the populations. Hence, the distributional pattern of Ph. monospermathecus from Baltic and North Sea beaches must be ascribed mainly to long-term and preference reactions and probably also to biotic factors (food supply, competition), and is less definable by short-term tolerances. This is in contrast to conspecific populations from Bermuda beaches. Here, the subtropical climate shifts the maximal oscillations of physiographical parameters close to the tolerance limits which makes the field distribution of the population explicable already by short-term survival tests (GIERE, 1977a). - Considering the differing distributional limits of Ph. monospermathecus in their climatically diverse habitats, the nature ot ecophysiological adaptation in this ubiquitous meiobenthic species is discussed.

Beschreibung: A working group of the Delta Institute at Yerseke, The Netherlands, studies the ecosystem of saline lake Grevelingen, a former estuary. The theme of the group is the cycling of organic matter in the two phases of the Grevelingen. The pool of particulate organic matter in the Grevelingen estuary (385 g C m-2 yr-1) was fed from various sources. The amount of organic carbon from the North Sea, entering the estuary as detritus equalled the in situ primary production. After the closure of the estuary the import of organic matter from the North Sea was completely cut off. Overall yearly production of the phytoplankton was not notably influenced by the closure, notwithstanding the large changes in environmental conditions. The significance of the phytobenthos production increased considerably. The total amount of organic matter available for consumers, decreased by roughly 40% to a level of 235 g C m-2 yr- 1. In the estuary net production of macrozoobenthos was estimated at 28 g C m- 2 yr-1. This production was almost divided by a factor two after the closure, just as the amount of food available. Changes in the feeding habits of birds may reflect the often less striking changes in the lower parts of the foodchains. Herbivore bird consumption has increased more than 20 fold after the closure. Consumption of zoobenthos showed a threefold decrease whereas the predation by fish-feeding birds increased about a 30 fold after the closure. The change from an estuarine into a stagnant saline ecosystem, bordering the North Sea, resulted in a sharp decrease in the amount of organic matter available as food, and a shift in the relative significance of predominant species.

Beschreibung: The distribution of the polychaete genus Nephtys in Kiel Bay was investigated using the 'stratified random sampling' method. The results revealed a distinct distribution pattern of the three occurring species according to sediment type. The inflowing North Sea water acts as an additional factor affecting the distribution. Niche separation of the genus Nephtys takes place by the combined action of two different mechanisms: preference for certain sediment types and tolerances to hydrographic factors such as reduced salinity and oxygen concentration.

Beschreibung: A respirometer for small benthic marine invertebrates is presented. The advantages of this construction are: compactness and easy transport of the equipment, small respiration chamber, entrance and exit electrodes close to respiration chamber, exact temperature control and equilibration of the experimental medium, exact regulation of the flow-through speed, digital display of consumed O2 values. The equipment is suitable for long-term measurement of O2 consumption by benthos organisms in low oxygen conditions and for a rapid picture of the reaction of experimental animals to abrupt changes in their environment (e.g. temperature, salinity, composition of the medium). Procedure for experiments involving a lowering of the O2 content of the medium is explained.

Beschreibung: The concept of grain size is critically reviewed and it is demonstrated that the conventional sieve method has some serious, system-inherent shortcomings. Sieve diameters do in many cases not reflect the requirements set by the theory on which they are based. The advantages of an alternative method of size analysis are discussed, in which the settling velocities of sedimentary particles in water are measured. These are then converted into standardized size equivalents and it is argued that the hydraulic nature of settling diameters provides more meaningful results for the study of depositional processess and animal-sediment relationships. A low-cost settling tube system, that is easy to build and simple to operate, is presented. lt is extremely fast when compared to conventional sieving and provides a significantly higher resolution of grain size distributions. The data is ideally suited for the application of moment measures for the computation of grain size statistics.

Beschreibung: Plankton samples were taken nearly every month in the years 1970/71. The neuston net sampled the surface plankton and the bongo net the rest of the water column. In total 32 species were found, most were numerically insignificant. The most abundant species were gobiids (more than 51 % ot total) followed by herring, sandeel, Onos and Pholis. Commercial species e.g. plaice, flounder or cod were rare. The majority of the fish larvae did not show a preference for the surface. Only Belone, Gasterosteus and Cyclopterus were caught almost exclusively in the surface layer.

Beschreibung: The material for this paper was collected from Gdansk Bay in November 1976 and January and March 1977. Hauls were taken from depths of about 5 metres, then every 10 metres from 20 to 100 metres. The frequency with which particular items of food occurred was calculated from the results of analyses of gut contents. The extent of digestion of food and amount of empty guts in the fish investigated formed the basis for estimation of feeding intensity of P. minutus. The greatest number of empty stomachs was found in January 1977 and the greatest quantity of food sampled during that period was found in fish taken from a depth of about 5 metres. The feeding intensity was about half this at greater depths (30-100 m). - The composition of food taken by P. minutus changed distinctly with depth, Neomysis integer and Nereis diversicolor predominated at smaller depths, whereas Antinoella sarsi was most numerous at greater depths. During the period in question, the diet of P. minutus was found to have a steady composition in fish taken from 70-100 metres and to be most varied at intermediate depths of 30-60 metres. The greatest number of empty stomachs was noted in smaller fish. Qualitative differences in food intake were not found to depend upon the size of the fish investigated.

Beschreibung: Arylsulphatase A and B were isolated from the hepatopancreas of the shrimp Crangon crangon L. after 7 days incubation in 50 ppm of detergent "SOLO". Arylsulphatase A, B-1 and B-2 were isolated from the hepatopancreas of the shrimp C. crangon L. incubated in pure brackish water (salinity 7‰). - Heavy and light fuel oil added to the enzyme in vitro in conc. of 2.0% inhibit the activity of arylsulphatase A in greater degree than arylsulphatase B (14.4% and 5.5% respectively). - Detergent "SOLO" (mixture of nonionic and anionic detergents) in the conc. of 0.5% inhibits for 58% arylsulphatase A and for 91% arylsulphatase B, whereas in conc. of 2.0% it inhibits arylsulphatase A for 91.7% and arylsulphatase B for 100%.

Beschreibung: Phytoplankton production was measured 19-25 times at three stations in the Sound during 1972 and 1973. The annual production in 1972 was about the same at all stations, 70- 77 g C m-2 yr-1. In 1973 a considerable difference was obtained, 73, 148 and 183 g C m-2 yr-1 for the three stations. The most obvious difference between the two years was observed during spring and summer in the north and central part of the Sound. The production in 1972 was about twice as high, and in 1973 4-5 times as high as previously reported for the Sound. The increased production in the Sound is to a large degree a result of eutrophication, but the natural changes in the unstable area must be considered important. A comparison with production values from adjacent waters and a discussion of factors controlling primary production in the Sound is presented.

Beschreibung: The influence of different temperatures and salinities on the toxicity of cadmium has been studied in short- and long-term experiments, using the colonial hydroid Clava multicornis as test organism. Clones were subcultured under prospective T/S-test conditions, applying 12 l recirculating seawater systems with biological water conditioning, glass plates for substratum, and Artemia nauplii for food. The inability of C. multicornis to catch and swallow prey induced by heavy metals was chosen as lethal criterion. - High temperature and low salinity within the ecological range of the species increased the acute toxicity of cadmium, while low temperature and high salinity enabled C. multicornic to resist higher metal concentrations in the water or delayed the appearance of reactions on pollution, respectively. The long-term sublethal threshold concentration of some 200 μg Cd · 1-1 was not affected by combinations of temperature from 5 to 20°C and salinity from 10 to 25‰.

Beschreibung: The energy flow of the pelagic part of a shallow water ecosystem is quantified using measurements of global incident radiation, particulate organic carbon, caloric content of the particulate matter, data from other authors on primary production, zooplankton secondary net production and zooplankton tertiary net production as well as several conversion factors from the literature. - The total potential radiant energy in 1973 amounted to 3.46 · 105 kcal m-2 y-1, the phytoplankton net production to 2.66 · 103 kcal m-2 y-1, with an average transfer efficiency of 0.77%. The zooplankton secondary and tertiary net production were 3.58 · 102 and 5.49 · 101 kcal m-2 y-1 respectively. More than 40% of the phytoplankton net production (1.08 · 103 kcal m-2 y-1) was remineralised within the water column, 35% of the phytoplankton net production (9.25 · 102 kcal m-2 y-1) sedimented directly to the bottom. The total transfer to the sediment amounted to 1.55 · 103 kcal m-2 y-1 (corresponding to 58.3% of the phytoplankton primary production), the further transfer to higher trophic levels was 4.34 · 101 kcal m-2 y-1 or 1.6% of the phytoplankton primary production.

Beschreibung: An attempt is made to describe the large-scale changes in the benthic soft bottom macrofauna in the deep parts of the Bornholm Basin, the Gulf of Gdansk, the Central Basin and the Gulf of Finland, from the beginning of Baltic zoobenthos research to the present day. The authors also try to correlate these changes with fluctuations in the oxygen content and salinity in near-bottom water layers. The paper surveys the literature and presents recent, earlier unpublished results. During the later part of last century and the first decades of the twentieth century no area of the Baltic Sea seems to have been total ly devoid of macrofauna. Unfortunately there are considerable gaps in our knowledge of the time before the middle of this century. The most striking decline has taken place, generally speaking, after the exceptionally great inflow in 1951-1952, and the subsequent prolonged stagnation. The first records of "dead" bottoms in the Bornholm Basin are from 1948, when no macrofauna was recorded below 80 m. Records from 1954 show that the deepest parts of the Eastern Gotland Basin and the deep area between Öland and Gotland were devoid of macrofauna at that time, but that the deep areas of the northernmost Baltic proper and the Gulf of Finland were still populated. The change continued, and during the 1960s the communities dominated by lamellibranchs in the Bornholm and Gdansk Deeps disappeared, and were subsequently replaced by polychaete cummunities. These have been wiped out during periods of bad oxygen conditions, but quickly re-established when conditions had improved. The lamellibranch community has not been restored. In the Northern Central Basin and the Gulf of Finland the depopulation of the deep bottoms probably began later, in the late 50s. In the 70s practically no macrofauna has been recorded below the permanent halocline in the Central Basin (except the southernmost parts of it) and the Gulf of Finland. During the 60s and 70s the area with periodically unfavourable oxygen conditions has covered about 100000 km2, which is c. 25 % of the total area of the Baltic Sea.

Beschreibung: The primary production of two of the most commonly distributed benthic algae in the Baltic proper was measured using different in situ methods (bottles, plastic bags, 14C and O2) during summer. Results on exudation and heterotrophic activity of these exudates have been worked out for Fucus. Low primary production and exudation values are found, while the total bacterial activity seems to be high compared to the net primary production.

Beschreibung: Feeding rate in juvenile flounder was measured at different experimental densities of Nereis diversicolor. The results are treated by means of a mathematical model that describes feeding rate as a function of prey density, prey size, fish size and temperature. Feeding rate increases with increasing prey density but at a decellerating rate until a level is reached. The position of the level is lowered with decreasing temperature and fish size and increasing prey size.

Beschreibung: This data volume presents a series of planktological observations carried out over a 19-year-period in Kiel Bight in the Western Baltic Sea. Three fixed stations (Boknis Eck: 1957 - 1975, Fehmarnbalt: 1951 - 1960, Breitgrund: 1960 - 1971) were visited at monthly intervals, and the plankton standing stock was investigated in relation to depth and environmental factors, employing a standard observation programme. This consisted in the measurement of temperature, salinity, (density), oxygen, (oxygen saturation), total phosphorus, PO4-phosphorus, seston, protein and chlorophyll a. Additional measurements comprised the caloric content of seston, particulate organic carbon and nitrogen (Boknis Eck: 1973 - 75), as well at dry weight and organic matter of p1ankton, sampled by vertical hauls of three plankton nets of different mesh size: 55 µm, 100 µm and 300 µm {Boknis Eck: 1963 - 75).