ALBERT

Description: A tsunami earthquake is defined as a shock which generates extensive tsunamis but relatively weak seismic waves. A comparative study is made for the two recent tsunami earthquakes, and a subduction mechanism near a deep-sea trench is discussed. These two earthquakes occurred at extremely shallow depths far off the coasts of the Kurile Islands and of eastern Hokkaido on October 20, 1963, and on June 10, 1975, respectively. Both can be regarded as an aftershock of the preceding larger events. Their tsunami heights and seismic wave amplitudes are compared with those of the preceding events. The results show that the time constants involved in the tsunami earthquakes are relatively long but not long enough to explain the observed disproportionality between the tsunamis and the seismic waves. The process times are estimated to be less than 100 s. The spatio-temporal characteristics of the two events suggest that they represent a seaward and upward extension of the rupture associated with a great earthquake which did not break the free surface at the coseismic stage. The amplitude and phase spectra of long-period surface waves and the long-period P waveforms indicate that this extension of the rupture did not take place entirely along the lithospheric interface emerging as a trench axis. It rather branched upward from the interface in a complex way through the wedge portion at the leading edge of the continental lithosphere. This wedge portion consists in large part of thick deformable sediments. A large vertical deformation and hence extensive tsunamis result from such a branching process. A shallowest source depth, steepening of rupture surfaces, and a deformable nature of the source region all enhance generation of tsunamis. The wedge portion ruptured by a tsunami earthquake is usually characterized by a very low seismic activity which is presumably due to ductility of the sediments. We suggest that this portion fractures in a brittle way to generate a tsunami earthquake when it is loaded suddenly by the occurrence of a great earthquake and that otherwise it yields slowly. Upward branching of the rupture from the lithospheric interface produces permanent deformation of the free surface which is relative uplift landward and relative subsidence trenchward of the zone of surface break. This surface break zone geomorphologically corresponds to the lower continental slope between the deep-sea terrace and the trench. Such a mode of permanent deformation seems to be consistent with a rising feature of the outer ridge of the deep-sea terrace and a depressional feature of the trench. This consistency implies a causal relationship between great earthquake activities and geomorphological features near the trench.

Description: A tsunami earthquake is defined as a shock which generates extensive tsunamis but relatively weak seismic waves. A comparative study is made for the two recent tsunami earthquakes, and a subduction mechanism near a deep-sea trench is discussed. These two earthquakes occurred at extremely shallow depths far off the coasts of the Kurile Islands and of eastern Hokkaido on October 20, 1963, and on June 10, 1975, respectively. Both can be regarded as an aftershock of the preceding larger events. Their tsunami heights and seismic wave amplitudes are compared with those of the preceding events. The results show that the time constants involved in the tsunami earthquakes are relatively long but not long enough to explain the observed disproportionality between the tsunamis and the seismic waves. The process times are estimated to be less than 100 s. The spatio-temporal characteristics of the two events suggest that they represent a seaward and upward extension of the rupture associated with a great earthquake which did not break the free surface at the coseismic stage. The amplitude and phase spectra of long-period surface waves and the long-period P waveforms indicate that this extension of the rupture did not take place entirely along the lithospheric interface emerging as a trench axis. It rather branched upward from the interface in a complex way through the wedge portion at the leading edge of the continental lithosphere. This wedge portion consists in large part of thick deformable sediments. A large vertical deformation and hence extensive tsunamis result from such a branching process. A shallowest source depth, steepening of rupture surfaces, and a deformable nature of the source region all enhance generation of tsunamis. The wedge portion ruptured by a tsunami earthquake is usually characterized by a very low seismic activity which is presumably due to ductility of the sediments. We suggest that this portion fractures in a brittle way to generate a tsunami earthquake when it is loaded suddenly by the occurrence of a great earthquake and that otherwise it yields slowly. Upward branching of the rupture from the lithospheric interface produces permanent deformation of the free surface which is relative uplift landward and relative subsidence trenchward of the zone of surface break. This surface break zone geomorphologically corresponds to the lower continental slope between the deep-sea terrace and the trench. Such a mode of permanent deformation seems to be consistent with a rising feature of the outer ridge of the deep-sea terrace and a depressional feature of the trench. This consistency implies a causal relationship between great earthquake activities and geomorphological features near the trench.

Description: One hundred and five new heat flow measurements in the Gulf of California support the premise that conductive heat loss is not the only mode by which heat is lost from a sea floor spreading center, even in an area with thick sediment cover. Theoretical estimates suggest that the average heat flow in the Guaymas and Farallon basins should be at least 11 μcal/cm2 s (HFU) (325 mW/m2). Outside a 30-km-wide zone centered on the central troughs, the heat flow values measured are reasonably uniform but average only 4.3±0.2 HFU (180±10 mW/m2). Although the high sedimentation rate may depress the measured heat flow, the effect probably does not exceed 15%. Some heat, particularly in the smaller basins, may be lost to the adjacent cooler continental blocks. The discrepancy between the measured and predicted heat losses, which is at least 30%, may be due to the discharge of thermal waters, through the thinner sediment cover in the central troughs or along active faults.

Description: The structural evolution of the northwestern Iberian margin has been reconstructed from the results of IPOD drill site 398, as well as from numerous dredgings and a dense network of seismic profiles. During the Mesozoíc the margin first underwent two consecutive extensional phases interpreted as the result of two episodes of rifting in the Atlantic. Then during Eocene, subsidence was interrupted by compression and related deformation caused by subduction of oceanic sea floor of the Bay of Biscay beneath the Iberian Peninsula. Present day marginal banks are interpreted as blocks of the older passive margin uplifted during early Tertiary as a result of that subduction. Fault escarpments provide opportunities to sample older sediments and basement by dredging.

Description: Deep sea sediments contain more Cu, Ni, Ba, B etc., than transport of detrital terrigenous matter (TM) can explain. Longdistance transport in dissolved from is of no importance for many of these elements. Marine biological matter (BM) is enriched in Cu, Ni, Ba, B etc. Conservative mixing models, using BM and TM as inputs show that the compositional variations in pelagic sediments can be explained by these sources. Such mixing models have been used to estimate how the influx of BM and TM have varied with time, and to what extent different elements ares upplied by BM and TM. The results show that in Cenozoic Equatorial Pacific sediments CaCO₃, opaline silica, B, Ba, and Cu are predominantly biogenous. It is probable that also P and Ni belong to this group of elements, whereas almost all Al, Ti, Zr, V and Mn are delivered by TM or some volcanic processes. The accumulation rates (AR) for the biological constituents reached maxima during the L. Oligocene and the Miocene, and minima during the U. Oligocene and the Pleistocene; some AR from the Oligocene and the Miocene being 3-6 times higher than at present. The accumulation rate patterns for opaline silica, Ba and B co-vary, whereas the AR for CaCO₃ show another time dependance pattern. These AR-patterns are probably partly due to climatic variations. Plankton in Pacific Equatorial waters incorporate much more Cu, Ni, etc., than is required for the particulate transport of these elements to the ocean floor. This suggests that transport in particulate form of BM is an important source of Cu, Ba, B, etc. for the deep sea floor.

Description: Several tissues (e.g. kidney, blood, digestive gland) in oceanic cephalopods which do not exhibit in vivo bioluminescence, luminesce when homogenized in the presence of air or when simply exposed to air in a vial (blood). The source of the luminescence appears to be a luciferin: treatment of kidney homogenates and blood with a photophore extract presumably containing luciferase resulted in a 20-fold increase in light production. Luminescence was also found in the renal fluid, which may be the source of luminescent clouds produced by squids. The variability in luminescence found in some tissues of cephalopods appeared to be related to feeding. Luminescence was also detected in the digestive glands of midwater octopods.

Description: The means of detecting downwelling light for counterillumination in several midwater animals has been examined. Eyes and extraocular photoreceptors (drosal photosensitive vesicles in the enoploteuthid squid Abraliopsis sp. B and pineal organs in the myctophid fish Myctophum spinosum) were alternately exposed to overhead light or covered by a small opaque shield above the animal and the bioluminescent response of the animal was monitored. Covering either the eyes or the extraocular photoreceptors resulted in a reduction in the intensity of counterillumination. Preliminary experiments examining the bioluminescent feedback mechanism for monitoring intensity of bioluminescence during counterillumination in the midwater squid Abralia trigonura indicated that the ventral photosensitive vesicles are responsible for bioluminescent feedback.

Description: The olivine melilitite diatemes of the Swabian Alb, frequently compared with kimberlite diatremes, are discussed in terms of hydrogeological setting, internal structure and juvenile fraction. The hydrogeological conditions of the Swabian Alb at the time of diatreme emplacement were characterized by copious amounts of groundwater within the sedimentary cover of the basement. Subsequently to the eruptions groundwater accumulated within the maars of the larger diatremes forming fresh‐water lakes as also happened nearby in the Steinheim and Ries impact craters. The diatremes reveal subsidence structures composed of large wall‐rock blocks, subaerially deposited pyroclastic beds, and well‐bedded reworked pyroclastic debris which accumulated on the floor of the fresh‐water crater lakes. The latter fact implies availability of groundwater at the time the diatremes formed. The juvenile fraction is developed in the shape of spherical to ovoid nucleated autoliths of ash to lapilli size that are macroscopically nearly devoid of vesicles. The autoliths are interpreted as the product of water vapor explosions which took place when rising olivine melilitite magma contacted groundwater and was fragmented into magma droplets. The droplets were rapidly chilled and thus preserved their shape. Because of the hydrogeological data, the diatreme structure, and the chilled nature of the autoliths a phreatomagmatic origin of the Swabian diatremes is suggested.

Description: Infrared and Mössbauer spectroscopy show that the extent of the reduction of nontronite is dependent on the chemical composition of the nontronite and on the nature of the reducing agent. Hydrazine reversibly reduces about 10% of the iron in all of the nontronites studied irrespective of composition and it is suggested that the resulting ferrous iron occurs only in distorted octahedral sites. Similar conclusions are reached for the dithionite reduction of the nontronites containing little tetrahedral iron, but for those with more than one in eight silicons replaced by iron, changes brought about by dithionite treatment are irreversible due to dissolution of appreciable quantities of iron. Results from both spectroscopic techniques suggest that iron in tetrahedral sites is preferentially dissolved and that up to 80% of the structural iron can be reduced. Evidence is presented for the formation in these extensively reduced nontronites of a small amount of a mica-like phase resembling celadonite or glauconite, and, as dithionite is used for the pretreatment of soils, the implication of this observation is briefly discussed. The use of deuterated hydrazine as a reducing agent has enabled the nontronite absorption band near 850 cm-1 to be assigned to a Si-O (apical) stretching vibration, which is inactive in the infrared for perfect hexagonal symmetry, but which is activated by distortions in the tetrahedral layer

Description: The olivine melilitite diatemes of the Swabian Alb, frequently compared with kimberlite diatremes, are discussed in terms of hydrogeological setting, internal structure and juvenile fraction. The hydrogeological conditions of the Swabian Alb at the time of diatreme emplacement were characterized by copious amounts of groundwater within the sedimentary cover of the basement. Subsequently to the eruptions groundwater accumulated within the maars of the larger diatremes forming fresh‐water lakes as also happened nearby in the Steinheim and Ries impact craters. The diatremes reveal subsidence structures composed of large wall‐rock blocks, subaerially deposited pyroclastic beds, and well‐bedded reworked pyroclastic debris which accumulated on the floor of the fresh‐water crater lakes. The latter fact implies availability of groundwater at the time the diatremes formed. The juvenile fraction is developed in the shape of spherical to ovoid nucleated autoliths of ash to lapilli size that are macroscopically nearly devoid of vesicles. The autoliths are interpreted as the product of water vapor explosions which took place when rising olivine melilitite magma contacted groundwater and was fragmented into magma droplets. The droplets were rapidly chilled and thus preserved their shape. Because of the hydrogeological data, the diatreme structure, and the chilled nature of the autoliths a phreatomagmatic origin of the Swabian diatremes is suggested.

Description: We present a plate kinematic evolution of the South Atlantic which is based largely on the determination of the equatorial fracture zone trends between the African and South American continental margins. Four main opening phases are dated by oceanic magnetic anomalies, notably MO, A34, and A13, and are correlated with volcanism and tectonic events on land around the South Atlantic Ocean. The Ceara and Sierra Leone rises are probably of oceanic origin and were created 80 m.y. ago or later in their present-day positions with respect to South America and Africa.

Description: Laboratory data are presented on the distribution of cobalt between pyrite, chalcopyrite, and pyrrhotite. Pyrite-type deposits are used to show that the results enable one to estimate the temperatures of formation for copper mineralization. Recent years have seen extensive studies on element distributions between coexisting minerals in order to define mineralogical thermometers and barometers [1-3]. Detailed studies have been made of the thermodynamic basis of such distributions, as well as of the factors that influence component levels in coexisting minerals. Here we will not consider a theoretical analysis of the distribution, but we do note that trace elements appear in pyrite and chalcopyrite only below the 1 wt. % level, while the compositions of the minerals deviate only slightly from stoichiometric, with temperature the main parameter that controls the distribution.

Description: This paper concerns the linear response of the ocean to forcing at a specified frequency and wave number in the absence of mean currents. It discusses the details of the forcing function, the general properties of the equations of motion, and possible simplifications of these equations. Two representations for the oceanic response to forcing are described in detail. One solution is in terms of the normal modes of the ocean. The vertical structure of these modes corresponds to that of the barotropic and baroclinic modes; their latitudinal structure corresponds to that of inertia‐gravity and Rossby waves. These waves are eigenfunctions of Laplace's tidal equations (LTE) with the frequency as eigenvalue. The description in terms of vertically standing modes is particularly useful if the forcing is nonlocal, because only these modes can propagate into undisturbed regions. The principal result is that it is extremely difficult for baroclinic (but not barotropic) disturbances to propagate horizontally away from a forced region. Instabilities of the Gulf Stream excite disturbances that are confined to the immediate neighborhood of the current; disturbances due to instabilities of equatorial currents do not propagate far latitudinally. A second representation of the oceanic response to forcing is in terms of vertically propagating, or vertically trapped, latitudinal modes. These modes are eigenfunctions of LTE with the equivalent depth h (not the frequency) as eigenvalue. Both positive and negative eigenvalues h are necessary for completeness. The modes with h 〉 0 consist of an infinite set of inertia‐gravity waves and a finite set of Rossby waves which either propagate vertically or form vertically standing modes. The latitudinally gravest modes are equatorially trapped and have been observed in the Atlantic and Pacific oceans. The modes with h 〈 0 are necessary to describe the oceanic response to nonresonant forcing. In the vertical this response attenuates with increasing distance from the forcing region. Because of the shallowness of the ocean the large eastward traveling atmospheric cyclones in mid‐latitudes and high latitudes force a response down to the ocean floor. Interaction with the bottom topography will result in smaller‐scale disturbances and will affect the frequency spectrum of the response when bottom‐trapped waves are excited.

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

Description: Data presented and discussed here were collected continuously during April/May 1975 in the Bornholm Basin of the Baltic Sea. Sedimentation rates of particulate matter were recorded with 5 multisample sediment traps from different depths in the water column at 2 positions 170 km apart. Current meter data collected during the same period and depths indicated that the positions remained hydrographically distinct during the investigation. Particulate matter from the euphotic zone including diatom cells formed the bulk of the material collected by all traps. This flux of organic particles to the bottom was unimpeded by the strong density stratification present in the water column. The upper traps always collected less material than lower ones. This paradox has been ascribed to diminishing current speeds with depth, concomitant with an increase in sinking rates of phytoplankton and phytodetritus. Both factors influence the sampling efficiency of sediment traps, which are thought to have underestimated actual sedimentation rates here. A time lag of 2 to 3 weeks in bloom development seemed responsible for the characteristic differences between the two positions. The phase of major sedimentation at one position covered about 18 days, and a distinct sequence in the composition of the material collected by the 6 glasses of each trap indicated phases of a progressively deteriorating phytoplankton population in the water column contributing the particulate material. A total of 6.2 g C m-2 in 34 days was recorded at this station. Apart from a trap situated in an oxygen deficient layer which collected 0.44 g C m-2 of zooplankton corpses, zooplankton mortality was overestimated by the traps. Large-scale sedimencation of “fresh” organic matter produced by the spring bloom is probably a regular feature in areas with low over-wintering zooplankton populations and, as such, possibly has a direct stimulatory effect on growth and reproduction of the benthos.

Description: An intensive three-dimensional survey of the Antarctic Polar Front was made in the Drake Passage in March 1976. The front, which was imbedded within one of the high-velocity cores of the circumpolar current, is viewed as a water mass boundary demarking the northern extent of near-surface antarctic waters. Within the front, water masses are observed to intrude, one above the other, with characteristic vertical scales of 50–100 m. The intrusions are horizontally anisotropic, being elongated in the alongstream direction and constrained primarily to the upper 800 m of the front. The spatial and temporal persistence of the variability is examined through the analysis of continuous vertical profiles of horizontal velocity, temperature, salinity, and oxygen with discrete sampling of nutrients. Analysis of the velocity data showed the mean current flowing to the NNE with speeds of the order of 30–40 cm s−1 in the upper 600 m, with temporal variability over a 28-hour ‘yo-yo’ due primarily to internal gravity waves. The thermohaline variability was not internal wave induced but rather was associated with nearly isentropic advection of different water masses across the front. Cold fresh and warm salty intrusions did not conserve potential density, however, and double-diffusive transfers are strongly suggested as being crucial to an understanding of the dynamics of the intrusions. Applying a model (Joyce, 1977) for lateral mixing we estimate poleward temperature and salinity fluxes due to interleaving of 0.086°C cm s−1 and 0.069‰ cm s−1, respectively. If these values are typical, interleaving could play a significant role in large-scale balance of salt and, to a lesser extent, heat for the Southern Ocean.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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%.

Description: 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.

Description: 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‰.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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).

Description: A new bacteriochlorophyll b containing phototrophic bacterium was isolated from extremely saline and alkaline soda lakes in Egypt. Enrichment and isolation were performed using a synthetic medium with high contents of sodium carbonate, sodium sulfate and sodium chloride. Photoautotrophic growth occurred with hydrogen sulfide as photosynthetic electron donor. During oxidation of sulfide to sulfate extracellular elemental sulfur globules appeared in the medium. Cells were also capable to grow under photoheterotrophic conditions with acetate, propionate, pyruvate, succinate, fumarate or malate as carbon sources and electron donors. Under these conditions sulfate was assimilated. Optimal growth under the applied experimental conditions occurred at a total salinity of 14–27%, a pH-range between 8.1 and 9.1 and a temperature between 47°C and 50°C. The cells were 0.5–0.6 μm wide and, depending on cultural conditions, 2.5–8.0 μm long; they were spiral shaped, multiplied by binary fission and were motile by means of bipolar flagella. Intercytoplasmic photosynthetic membranes were present as stacks. Bacteriochlorophyll b was the main photosynthetic pigment; small amounts of carotenoids were mainly present as glucosides of rhodopin and its methoxy derivative. The new organism is described as Ectothiorhodospira halochloris.