ALBERT

Description: The dynamic and production of a natural population of the rotifer Brachionus plicatilis (0.F. MÜLLER) were studied by regular field sampling at routine stations in the shallow Darss Zingst estuary, southern Baltic (3-7‰ S). Investigations of the horizontal distribution revealed significant population growth during the summer months at salinities above 3‰ S and at those stations characterized by high eutrophication. The first individuals hatch from resting eggs in May. Significant reproduction occurs from June to September, when temperatures are above 15° C. Mixis rates were highest during the exponential growth phase. Instantaneous rates of growth, birth, and mortality were estimated. Mean P/B ratios for the growing season were high (around 0.7 d-1) and were in the range of values obtained from mass cultures in the field under subtropical conditions. In Barther Bodden annual biomass production for 1982 was 1.1 g fw · m-3. In its natural habitat, B. plicatilis serves as a food source for fish juveniles and the mysid Neomysis integer, the seasonal dynamics of the rotifer population were not significantly affected by predators.

Description: Shrimps Crangon crangon L. were exposed to 5, 7.5, 10, 25 and 50 ppm of the anionic detergent alkylbenzene sulphonate (ABS) added to brackish water (7‰ salinity). The animals were incubated in these solutions from one to nine days at 15° C or 20° C. After 24 h and 108 h of incubation the activities of arylsulphatase (E.C. 3.1.6.1 ), acid phosphatase (E.C. 3.1.3.2) and cathepsin D (E.C. 3.4.4.23) were assayed in homogenates of the hepatopancreas. The influence of the detergent ABS on the moulting cycle of the shrimps was also investigated. The activity of all acid hydrolases assayed descreased by 20 % to 50 % in the experimental shrimps, depending on concentration of the pollutant, as compared with the control group. The moulting cycle of the shrimps exposed to the action of the detergent was shortened from 31 % to 51 %, and the body weight during one moulting cycle was reduced by 24 % to 36 %. Survival times were reduced in the animals exposed to the action of the detergent. Total mortality of the shrimps occurred after 194 h, in 5 ppm of ABS at 15° C and after 108 h in 50 ppm. The 96 h LC50 for shrimp Crangon crangon L. under laboratory conditions was estimated as 27 ppm of alkylbenzene sulphonate.

Description: Prior to 1975, average winter water nutrient concentrations at station Bokniseck in Kieler Bucht (Western Baltic} were 1.23 mmol/m3 total phosphorus and 12.7 mmol/m3 dissolved inorganic nitrogen. Nitrogen concentrations did not change until 1984. The mean of a few total phosphorus data from 1980-1984 is 1.94 mmol/m3. Mean nutrient concentrations in the area between the southern entrance of the Great Belt and Darss Sill increased between 1975 and 1984 from 0.8 to 1.6 mmol/m3 total phosphorus and from about 6 to 10 mmol/m3 inorganic nitrogen. Comparatively higher nutrient concentrations at Bokniseck station are correlated to higher salinity. However, no data are available on nutrient imports into Kieler Bucht with saline deep water. Unchanged nutrient concentrations at Bokniseck prior to 1975 are an argument against any dominant influence of anthroprogenic inputs which until 1974 increased to annually 1500 t of total phosphorus and 12700 t of total nitrogen, plus 5000 t of nitrogen from the atmosphere. Higher phosphorus concentrations 1980-1984 are correlated to severe oxygen deficiency in the deep water. Mobilization of phosphorus from sediments becoming anoxic could be the reason. Biota could be such sources and sinks of nutrients that influence the nutrient balance of Kieler Bucht. To sum up, there are several processes besides anthropogenic inputs that influence nutrient concentrations in water. An assessment of winter water nutrient concentrations alone is no adequate tool for the evaluation of the effects of anthropogenic nutrient inputs via rivers, sewage, land runoff, groundwater and from the atmosphere.

Description: Postglacial sequence of migration and extinction has been studied in a boring through 10 m deposits in Jutland, Denmark. The main profile contained freshwater and brackish water fauna in the bottom layer. Hydrobia ulvae was first recorded at -9.75 m. Next H. ventrosa was found together with H. ulvae. Then H. neglecta appeared, and all 3 species co-occurred at -8.75 m. At -4.95 m H. ulvae disappeared but H. ventrosa and H. neglecta were still abundant until a depth of -1.90 m. It is concluded that H. ulvae and H. ventrosa quickly colonized the Littorina Sea while H. neglecta may have arrived somewhat later. H. ulvae has the largest larval shell, especially in the Baltic, and H. ventrosa the smallest larval shell of the 3 species. The ecological significance of two markedly different shell forms of H. ulvae is discussed. Postglacial hydrobiids are compared with recent specimens of the 3 species.

Description: In situ measurements of the functional response (feeding, respiration and excretion) of Mytilus edulis and Ciona intestinalis showed that the effects of 2.5 µg 1-1 tributyl tin and 100 µg 1-1 cadmium on an assemblage of the two species was lower than what could be predicted from the response of the two species separately. This is explained by biological interactions between the species and by the fact that the two species may react in different ways to the same disturbance. Thus, results from single species tests seem inadequate for making predictions of pollution effects in marine environments, and tests should instead be carried out at the community or ecosystem level.

Description: In order to determine the time of settlement, growth and mortality of young bivalves, samples sieved on 250 µm screens were taken in parallel to ordinary samples (1 mm screen) in the western part of the Limfjord, Denmark. High densities of newly settled Corbula gibba (30000-67000/m2) and Abra alba (16000-22000/m2) in August 1986 were found at most stations. Growth of the juvenile Corbula gibba was very rapid and the specimens were retained by the 1 mm sieve a few weeks after settlement. Growth ceased in October at a length of 2.9-3.5 mm for Corbula gibba and 0. 7-2.1 mm for Abra alba. The juvenile bivalves suffered high mortality within the first month after settling. It is suggested that this mortality may be due to predation from epibenthic predators.

Description: Seawater samples for algal experiments and isolation of OHS (Dissolved Humic Substances) were taken in the Gdansk Bay during intense phytoplankton blooms. Bioassay experiments were conducted under controlled laboratory conditions with water containing natural phytoplankton communities. OHS was isolated from seawater by absorption on Amberlite XA0-2 according to the method of MANTOURA and RILEY (1975). It was found that the enrichment of the medium with OHS increased the production of chlorophyll a and cell numbers. OHS addition to the culture medium caused a change in the dominant species, especially in spring and summer phytoplankton. The results show that OHS influence not only the phytoplankton production but also the species succession by altering the species composition. The phenomenon of large phytoplankton blooms in coastal areas during the last decade should therefore be related (besides other physical, chemical and biological influences) to the presence of increasing concentrations of dissolved substances of the humic type.

Description: In 1986 and 1987 a transect off SW Åland, N Baltic Sea was sampled for macrozoobenthos at 14 stations ranging from 1 to 226 m depth. In connection to this survey comparative samples were taken at a "standard depth" of 19-20 m at 2 additional stations to estimate variability in space and time. The data were analyzed for primary community parameters (i.e. no. of species, abundance and biomass) including spatial and temporal differences, and the information is evaluated in relation to topography and hydrography. A more detailed analysis using the dominant components of the zoobenthic communities illustrated some of the difficulties in monitoring of the marine zoobenthos. There were significant differences in abundances and biomasses even over short distances. The differences get even more pronounced when trying to relocate an exact station with another boat and using different grab types on the same station. This is exemplified by samples from a 19-meter station using a modified Olausen box corer and an Ekman-Birge type grab sampling on different days from different vessels; the primary community data obtained with both grabs was 10 vs. 10 species (with Pontoporeia affinis vs. Macoma balthica dominating), 1945 ± 529 vs. 2168 ± 385 ind/m2, and 21.6 ± 9.5 vs. 209.0 ± 45.3 g/m2, respectively. Similarily, samplings at stations less than 1 n. mile apart at 20 m depth using the Ekman-Birge grab yielded 2168 ± 385 and 7000 ± 607 ind/m2; a highly significant difference. The no. of species (10/13) and biomasses (209.0 ± 45.3/184 ± 89.0 g/m2) showed no significant differences. The data also showed some depth dependency, but there was no correlation (r=0.22) between abundance and biomass for the entire material pooled, illustrating the importance of always measuring both. When using keyspecies for monitoring purposes, their natural distribution should also be known, as the dominance-patterns shows clear gradients with depth and sediment type.

Description: During the winter 1984 and summer 1985, a series of limiting nutrient experiments (enrichment tests) were performed with coastal Baltic water by scientists from the German Democratic Republic, Poland and Sweden. The water used for the experiments was collected outside Warnemünde (GDR); Rostock (GDR}, Sopot (P) and Falsterbo (S). The bioassays were performed under similar laboratory conditions. Nitrogen was the potentially most limiting nutrient for phytoplankton biomass formation in coastal water from Rostock, Sopot and Falsterbo. During winter, before the spring phytoplankton bloom had started, phosphorus was the "most limiting" nutrient in the Rostock area. For the Warnemünde area, no clear limiting nutrient was found, except during July 1984, when nitrogen addition doubled the phytoplankton biomass. The lowest algal standing stocks were found for Warnemünde and Falsterbo, followed by Sopot. Extremely high chlorophyll-a values were found outside Rostock. Our results show that these coastal areas in the southern Baltic do not differ essentially from each other with respect to the most limiting nutrient (sensu Liebig), although their nutrient levels are quite different. Nutrient limitation experiments are discussed in the context of the assumed eutrophication of the Baltic.

Description: The paper presents the assumptions of a one-dimensional mathematical model of turbulent diffusion of marine suspensions, as well as the results of numerical investigations on the influence of dynamic conditions in a defined basin on the chlorophyll-a concentration. The influence of the duration and disappearance time of a disturbance, and the thickness of the layer disturbing uniform media of varying degrees of turbulence on the vertical distribution of the chlorophyll-a concentration is analysed.

Description: A large scale quantitative survey of the benthic vegetation of the Kiel Bight (Western Baltic Sea) has been performed by analysis of underwater television observations and samples obtained by SCUBA diving during 1985-86. This investigation was compared to a semiquantitative survey carried out in 1962-64 by SCHWENKE (1964, 1969). For the total study area (2571 km2), distinct changes in biomass and species composition have been observed. There is an increase of biomass above the 12 m level (probably with exception of the 6 m level) and a decrease below 12 m. Extensive Furcellaria lumbricalis populations have disappeared. Furcellaria lumbricalis has been replaced by Phyllophora truncata and Phycodrys rubens which are the predominant species at present. Among other possible causes for these changes, the role of commercial stone fishing and effects of increasing eutrophication in the Kiel Bight are discussed.

Description: The establishment of an initial association of marine benthos was investigated during a colonization experiment at the "Nordsee" research platform at 25 m depth, from April to December 1985 and 1986. Settlement and the early stages of succession were studied by taking monthly series of soft-bottom samples. Parallel to the experiment, recruitment in the natural habitat was studied at a reference station close to the platform. Number of species, density, diversity and evenness of the initial experimental association showed 3 different phases, similar to those described by RUMOHR (1980) as "pre-opportunistic, opportunistic and post-opportunistic" phases. These stages appear regularly during early succession, but, are subject to strong seasonal and annual variability. Heavy spatfalls of several species occurred in both years of the investigation; e.g. Tellina tabula, Echinocardium cordatum, juvenile ophiuroids of the genus Ophiura (mainly in 1985) and Scoloplos armiger, Mediomastus aff. fragilis and Abra sp. (1986). Total density attained maximum values of approx. 30,000 ind. per 0.1 m2. In the natural environment the colonization process was similar, but as in Kiel Bay, the densities were much lower than on the experimental substrates. The successional pattern and role of opportunists during early succession is discussed.

Description: Sven EKMAN (1876-1964), zoogeographer and limnologist in Uppsala, wrote significant articles on marine glacial relicts, drew up a proposal of the natural history division of the Baltic Sea and wrote the textbook "Tiergeographie des Meeres", first of its kind and later published in English as "Zoogeography of the Sea". - Adolf REMANE (1898-1976), zoosystematician and ecologist in Kiel, was one of the first to analyse the faunal composition and communities of the Baltic in "Die Tierwelt der Nord-und Ostsee". A pioneering textbook by him and C. SCHLIEPER "Biologie des Brackwassers" appeared also in English. REMANE found the interstitial habitat. He described numerous new Gastrotrichs, Rotifers and Archiannelids. - Carl SCHLIEPER (*1903), zoophysiologist in Kiel, is the founder of the "School of Baltic physiologists". Studies by him and his many students on salt water tolerance and osmoregulation, ionic and temperature adaptation and high pressure tolerance of aquatic animals are known world wide. He is the co-author of four textbooks. Sven G. SEGERSTRÅLE (*1899), zooecologist in Helsinki, initiated the yearly monitoring of the bottom fauna in coastal waters of Finland. He studied the systematics and ecology of amphipods, especially the genus Gammarus and Pontoporeia and biology of the mussel Macoma balthica. His descriptive articles on the Baltic Sea and studies on marine glacial relicts are well known.

Description: The effect of siderophores, cysteine and Na2EDTA in cultures of Chlorella vulgaris and Anabaena variabilis containing copper or cadmium, on the chlorophyll-a content, as well as on the rate of carbon fixation, has been investigated. Experiments on copper accumulation in Chlorella vulgaris cells grown in the presence of organic compounds have been also carried out. The siderophores, cysteine and Na2EDTA reduced the toxicity of copper and cadmium to axenic strains of algae and natural phytoplankton. No correlation between the toxic effect of copper and its bioavailability was observed.

Description: In the last 14 years, trapnet catches of the Baltic herring (Clupea harengus membras L.) have decreased drastically in the inner zones of the bays studied, but increased in the outer zones in the sea area of Turku, SW Finland. We deduce that the reasons for the decrease of catches have been eutrophication and sedimentation of the bays. The spawning grounds of the Baltic herring were studied by SCUBA-diving in the sea area of Turku in 1981-86. We studied 134 locations but found eggs in only 20 locations. Herring did not lay eggs on all suitable grounds, but regularly and intensively used some few locations from year to year. The most important spawning grounds were situated in the outer zones of the bays. We found eggs at 0-8 meters depth. In the inner parts of the bays, we did not find eggs with the exception of one shore, which is kept free of sediments by water currents. The spawning grounds comprised mainly sand and gravel. Most of them were covered by vegetation. Eggs were attached to Cladophora glomerata, Potamogeton perfoliatus, and red algae Furcellaria Jumbricalis and Phyllophora truncata. In the innermost zones of the bays the original littoral hard bottoms have changed to soft, muddy bottoms and consequently no eggs could be found there.

Description: In 1985 and 1986, a SW Finnish archipelago area was monitored for fish (using gillnets and seine), in order to investigate potential effects of salmonid fish farming on natural fish communities (population- and community level, growth and food choice). The results indicate some structural change eg. in total abundance and biomass values (increasing), on species composition (towards moore cyprinid-dominated communities), on growth rate (increasing) and food choice (increased proportions of fish consumed) of perch, and a general shift towards communities dominated by juveniles and small fish in areas influenced by fish farms.

Description: Recruitment and survival of Nereis diversicolor and Corophium volutator was studied in an artificial Saltwater Lagoon in the Danish Wadden Sea. The two species were the most successful colonizers of this lagoon and they have temporarily accounted for more than 80 % of the benthic individuals. Predation by waders, emigration and a low salinity in winter(〈2‰) appeared to be important regulators of the population sizes. Various field experiments have been performed to examine the effect of selected infaunal species on recruitment of C. volutator and N. diversicolor. The density of recruits of C. volutator was negatively affected by adult individuals of its own species, by C. arenarium, by Macoma balthica, and by Nereis diversicolor. C. arenarium was the only species that had a negative effect on N. diversicolor. At the intertidal flat a high recruitment of both, C. volutator and N. diversicolor, took place within cages enclosing the natural fauna, while the density of recruits on the adjacent bottom was low. The importance of epibenthic predators and cage artifacts on the density of recruits is discussed.

Description: The influence of eutrophication on the occurrence of the red algae Furcellaria lumbricalis and Phyllophora truncata was studied in the sea area of Turku. Due to increased sediment load and planktonic production, light penetration in the water has decreased in the northern parts of the study area. Furthermore, the quality of the sea bottom has changed. Plots of 1 m2 (N = 100} in the upper littoral zone (0.5-6 m} were studied by SCUBA diving, in order to investigate the factors controlling the occurrence of the red algae. Two transects were situated in the eutrophicated area, and two in the reference area. In the plots, the percentage cover of each plant species and of Mytilus edulis was documented, and the Secchi disc visibility and depth was measured. The numerical data were analyzed by correlation analysis and stepwise multiple regression analysis (BMDP2R}. In the eutrophicated area, abiotic factors (percentage cover of plain bottom and bottom quality} explained 81.28 % of the variation of red algae cover. In the reference area, the biotic factors (total number of species and Mytilus cover in %} were the most important factors, explaining 66.4 % of red algae cover.

Description: Major inflows of saline water into the Baltic Sea have a significant impact on the oceanological regime of the deep water in the central basins. Such events show seasonal characteristics, which are investigated here for the 80-year period from 1897 to 1976. The characteristic properties - i.e. salinity, temperature, density and oxygen concentration of the water bodies entering the Baltic during major inflows are analyzed for the first time. The significance of the season of the inflow event for its effects on the oceanological conditions in the deep water is discussed.

Description: 12-year quantitative phytoplankton data collected in the Tvarminne sea area in June-August from 1972-1985 were analysed in relation to environmental data collected at the same time. This was done by principal component analysis followed by canonical correlation analysis. A phytoplankton species succession which took place parallel to the increase in temperature was found to be the most important factor causing variation in species composition. The second most important factor was a change in phytoplankton species composition from the early 1970's towards the 1980's. This followed the same pattern as nutrient levels and total phytoplankton biomass. The species primarily responsible for the change were nanoplanktonic forms, such as unidentified flagellates, Cryptomonas spp., Monoraphidium contortum and Microcystis reinboldii, and a heterotroph, Ebria tripartita. It was concluded that this was due to increased levels of total phosphorus and organic load in the Gulf of Finland. Short-term weather conditions had no significant effect on species composition.

Description: The history of studies of benthic flora and fauna in the Northern Baltic Sea (N of 58° N, including the Gulfs) is briefly reviewed from the early naturalists of the Linnaean period (mid-18th century) to the early 1970's.

Description: Fish eggs and larvae were sampled during 1970 and 1971 at approximately monthly intervals in the Kiel Bay using a Bongo-Net. Samples of 0.5 mm mesh net were considered in this study. At every station temperature and salinity were measured. The most abundant fish eggs were of sprat origin, followed by flounder, cod and plaice. Spawning areas of this species are also described. Fish larvae showed high abundance from June to August with gobies predominance. Commercially important species such as herring, cod and plaice were present in low numbers. Species exceeding the 5 % relative proportion level (tow-year average) were herring, sprat, rockling, gobies and gunnel.

Description: The Bornholm Basin has a distinct hydrographical pattern in terms of temperature, salinity and oxygen. Due to the strong differences in density, there is a strong vertical stratification of water masses and ichthyoplankton as well. The vertical distribution of fish eggs and larvae was investigated in a period of 27 hours at an anchor station. Samples were taken at three hours intervals with a closing net. The species composition of fish eggs and fish larvae in (), both in percent, was found to be 79.7 (84.0) sprat, 17.5 (15.0) cod, 1.3 (0.6) rockling, 1.5 (0.4) flounder and 7.3 dead eggs. To control for water masses around the station, double oblique hauls with a ring net were performed, as well as measurements of temperature and salinity. The vertical distribution of sprat and cod eggs showed considerable differences. Sprat eggs were most abundant in the upper 40 metres, whereas cod eggs were found only from 40 metres downwards. The few eggs of rockling and flounder showed a weak accumulation between 40 to 65 metres. Sprat and cod larvae were present throughout the whole water column, decreasing in numbers with depth. The maximum abundance overlapped for sprat and cod between 40 to 65 metres. However, sprats were also common in the upper layer, in which cod were present in small numbers only. The larvae of rockling and flounder were generally scarce and not found in every sample. No aggregation was obvious at certain depth levels.

Description: Predation on zoobenthos by fish was studied on Åland, northern Baltic Sea, in a shallow, semi-isolated bay (Station 1) and an outer area (Station 2) which is in direct connection with the bay. The fish sampling was done under an one year-cycle (May-November 1984 - May-June 1985) with a standardized multimesh set of gillnets. The fish samples for community analysis were taken once a month (May-November 1984 - May-June 1985). Stomach samples of perch (Perca fluviatilis, L.), roach (Rutilus rutilus, L.) and ruffe (Acerina cernua, L.) were collected five times during the sampling period representing the spring-, summer- and autumn-seasons. The fish species studied are the most important predators on benthic macroinvertebrates in this area. Calculations of the annual food consumption were done on the basis of field data and literature values. The soft bottom infauna was monitored throughout the study to get accurate measures of the standing stock. Roach was the most abundant and important bottom feeder in the study areas. It consumed 64 to 73 % of the total amount of benthic food taken. Roach preyed heaviest on molluscs. Perch preyed mainly on crustaceans (at St. 2) and insect-larvae (at St. 1). It consumed about 24 to 35 % of the total amount of fish predation. Ruffe is principally an obligate benthic feeder consuming mainly insect-larvae, crustaceans and polychaetes. The abundances of ruffe were low in the study areas, and the quantities consumed were marginal on an annual basis. The total consumption calculated was 999 kg/ha at St. 2 and 349 kg/ha at St. 1 during the summer season (May-November). Consumption is significantly higher in the outer area (St. 2) mainly due to higher fish abundances and benthic biomass in this area. The consumption values are equivalent to about 9 to 31 % of the annual secondary benthic production in the area studied. The fish consumed a significant proportion of the benthic standing stock, but simultaneous experiments in the lab and field have shown that the structuring effect of fish-predation on the benthic community is small. The ecological relevance of the fish/benthos couplings on shallow soft bottoms are further emphasized.

Description: In static toxicity tests, the effects of HgCl2 and of an organic mercury complex on the mortality of Neomysis integer and Pomatoschistus microps were determined under various temperature and salinity conditions. Definite species-specific differences with respect to combined temperature, salinity and mercury effects were found. The toxicity of the organic mercury complex exceeded that of HgCl2 by a factor of 20 in the case of N. integer, and by a factor of 30 in the case of P. microps. By means of continuous respiration and activity measurements on N. integer (the more sensitive species) under organo-mercury contamination at different environmental conditions (temperature, salinity and pO2), reproducible sublethal concentrations were determined. For this species, a direct relationship was found between mercury contamination levels, increase in activity, and oxygen uptake.

Description: On the occasion of the celebrations of the 50th year of existence of the biological station at Hiddensee (1982), the 150th jubilee year of the Zoological Institute of the Ernst-Moritz-Arndt-University in Greifswald (1986), and the 25th year of existence of an independent marine biological research and training facility at the University of Rostock (1985), a short overview is given of the development of biological science in the Baltic Sea in the Hither Pomerania and Mecklenburg region. It will become clear that the initiative for brackish water research arose at the University of Greifswald, with algological studies concentrated at Hiddensee and zoological-ecological work in Greifswald itself. Effective and successful marine biological research and teaching at the University of Rostock started with the establishment of the Department of Marine Biology (1960), where university marine biological activities are now concentrated as a result of the university reform (1968).

Description: Shrimps (Crangon crangon L.) were exposed to 5, 7.5, 10, 25, or 50 ppm of light fuel oil, heavy fuel oil or crude oil at 15° C or 20° C with aeration. The mortality was recorded. It was found that light fuel oil was the most toxic and crude oil the least toxic.

Description: The genus Enteromorpha Link is one of the most common algae in the Gulf of Gdańsk. The literature mentions that several Enteromorpha species occur in the western part of the Gulf of Gdańsk. The material for analysis was collected in the littoral zone down to a depth of 1 m in the Gulf of Gdańsk and on the open Baltic coast once a month from April to November 1986. The taxonomical characters, the nature of the bottom sediments and the sampling season were used for describing OTUs. 6 dissimilarity coefficients and 7 clustering methods were employed. The two principal clusters and some intermediate OTUs are shown on the dendrograms. The difference between these two clusters lies in the morphological characters. In one of them, the filaments are unbranched, without prolification, and the cells are multilateral and rounded, setting in random fashion; in the second one the filaments are branched, and the cells are rectangular, setting in an orderly manner along the main axis and the branches. The remaining characters, especially the quantitative ones do not seem to be important from the cluster analysis point of view.

Description: Cadmium, lead, copper, chromium and zinc contents were determined in otoliths of the cod Gadus morhua L. from the Southern Baltic. It was shown that the levels of these heavy metals fluctuated during the period of investigation (1969-1985). It was found that levels of Cd, Cu, Cr and Zn decreased with age and age-dependent morphometric parameters, while the amount of lead increased. Sex of cod did not affect the level of bioaccumulation of these five trace elements in the otoliths. With the exception of Cu no differences were found between heavy metal contents in otoliths of cod from the Gdańsk and Bornholm Deep.

Description: Following a mass mortality of the demersal fish population in Kiel Fjord due to anoxic water conditions throughout the water column, the occurrence of mass aggregations of the free-living marine nematode Pontonema vulgare on dead fish, jellyfish (Aurelia aurita, Cyanea capillata) and starfish (Asterias rubens), and in weakened mussels (Mytilus edulis) was observed by SCUBA diving and documented through underwater photography as early as two days after the incident occurred. P. vulgare not only survived the anoxic conditions which prevailed for severals days, but also took advantage of these circumstances to prey upon dead or weakened animals on the sediment. These observations confirm previous reports of a possible role of Pontonema vulgare as a scavenger in the form of mass aggregations in areas of acute oxygen depletion and sediments of high organic content. Positive thigmotaxis is assumed to cause aggregations of Pontonema vulgare upon brown sediments and on webs of Beggiatoa spec. in oxic water with no apparent prey as a cause. Their chemoreceptive sense, thigmotactic aggregation behavior, ability to withstand adverse oxygen conditions, and their broad feeding spectrum are responsible for the success of this species in an extreme environment.

Description: Based on data collected at 7 stations 4 times a year in 1985 and 1986, composition and distribution of meiobenthic communities in the Polish part of the Szczecin Lagoon, a eutrophic and polluted water body connected with the Baltic Sea, is presented. The data show a tendency to reduced total meiobenthos densities and diversity from the lower to upper reaches of the lagoon. The meiobenthic communities studied were dominated by nematodes, ostracods ranking second in numerical importance. Harpacticoid copepods were most abundant at the outer stations which are influenced by Baltic inflows. Most of the 10 harpacticoid species recorded in the lagoon were found at the outer stations (lower reaches) as well. Similarity analysis allowed to separate three zones within the lagoon: (1) the outer zone, its stations showing most abundant and diverse meiobenthic communities; (2) the innermost zone (upper reaches) with the least abundant and qualitatively impoverished communities; and (3) the intermediate zone.

Description: An approach to monitoring the availability of oxygen to benthic marine invertebrates in the sediment is presented on the basis of biochemical analyses of metabolites of species from Kiel Bight. In Halicryptus spinulosus, Astarte borealis and Arctica islandica several metabolites of anaerobic metabolism were examined for their suitability as indicator substances of the oxygen availability. The amino acids aspartic acid and alanine seem to be useful only as indicators of short-term anaerobiosis, whereas glycogen and succinate together may indicate the overall duration of long-term anaerobiosis. The time course of glycogen depletion and of the increase of succinate concentrations in the tissues is correlated to the duration of experimentally induced anaerobiosis. Analyses of freshly captured Halicryptus spinulosus reflect the occurrence of long-term anaerobiosis at the sampling site in Kiel Bight during the end of summer and early autumn. Succinate concentrations in these worms and the depletion of glycogen came close to the values of specimens kept in the laboratory under anoxic conditions for 40 days (at 10°C).

Description: On the basis of long-term investigations, the course of seasonal variations of mean daily primary production and mean chlorophyll-a concentration in the Southern Baltic waters are presented. The mean annual primary production of the Gdańsk Deep, Bornholm Deep and the Gotland Deep amounted to 124.4 gC m-2, 88.8 gC m-2 and 107.2 gC m-2, respectively. The primary production of the Southern Baltic in 1986 was higher than in 1985, and higher than the long-term mean value. The mean annual production for the Southern Baltic in 1986 amounted to 130 gC m-2. On the basis of long-term observations of primary production and chlorophyll-a of the Southern Baltic, certain upward trends in phytoplankton production were observed.

Description: The nutrient situation in eutrophic shallow coastal water systems is characterized by particular features. In addition to water exchange with the open sea, interactions at the sediment/water interface play a significant role. With the help of investigation on phosphate sorption/desorption balances and on the denitrification capacity of shallow coastal waters, the following general conclusions can be made: The phosphate concentrations in the water are primarily determined by physico-chemical reactions with the sediment, and less by the rhythm of the phytoplankton primary production. Through intensive interactions between sediment and water, a phosphate "equilibrium" concentration which fluctuates very little is maintained over the whole year. High primary production rates are possible at these low equilibrium concentrations of phosphate. The phosphate sorption capacity of sediments is a characteristic parameter of shallow systems. Sediments with a high organic matter content exhibit the highest phosphate sorption capacities. With the development of nearly anearobic conditions, nitrate reduction can occur at a rate, when the appropriate amount of nitrate is made available to the reaction. Under optimal conditions for nitrate reduction, nitrate concentration is also not a parameter characterizing the nature of the water body.

Description: During 1982, 1983 and 1984 numbers of planulae within the oral arms of the common jellyfish Aurelia aurita were counted, and the organic content of the larvae was determined through C/N analysis. The total numbers of larvae produced by females of the same size increased during the period of investigation by a factor of 4-5, and a good linear correlation between the amount of larvae and body weight of the females were observed. In contrast, the averaged carbon content of the planulae decreased from 0.68 µg C per individual in 1982 to 0.28 µg C per individual in 1984. On average, larvae represented 17% of the carbon content of a female in 1982, 25% in 1983 and 37% in 1984. Partitioning of this organic matter among larvae differed from year to year: low numbers of planulae with a high organic content were observed in 1982, very high numbers with a low organic content in 1984, and intermediate in 1983. Thus breeding behaviour of the common jellyfish seems to be a complex process and there is evidence that medusae abundance and estimated food availability ragulate reproduction in Aurelia aurita populations.

Description: The energy content of Mysis mixta from the Southern Baltic in relation to its body weight was studied in June, August and October 1986, and April and May 1987. In June, immature animals (4-13 mm) and adult females (18-25 mm) dominated. The same composition was found in August, although the size had changed: the immature animals ranged from 10 to 21 mm and adult females from 21 to 30 mm. A more homogeneous population ranging from 12 to 22 mm was found in October. Males occurred in large numbers only in autumn. The dry weight was 15.04 % of the wet weight, and included 8.18% ash. The relationship between dry weight and body length fitted the power function W = 0.714 L2.835. The average energy content of M. mixta was high: 24.748 Jmg-1 OW and 27.055 Jmg-1 AFDW.There was no significant difference in energy content between adult females and males in October, when both sexes were present. Energy content per dry weight increased with the size of the animals. M. mixta obtained in the study area showed similar energy content to each other.

Description: Shrimps Crangon crangon L., acclimated in the laboratory for 24 h in brackish water (7‰ salinity), were incubated in solutions of anionic detergent alkylbenzene sulphonate (ABS) in concentrations of 5 - 50 ppm. After 24 h or 96 h of incubation, preparations of hepatopancreas were stained and examined by light or transmission electrone microscopy. The light microscopy examination revealed a flattening of the duct cells, pyknotic nuclei in these cells, fine granular secretions in the ducts of the gland, and cellular infiltration. The transmission electron microscopy examination revealed an impairment and destruction of the lysosomal and mitochondrial membranes of the hepatopancreas cells in the shrimps exposed to alkylbenzene sulphonate.

Description: In spring, summer and autumn enclosure experiments were performed in the central part of the Arkona Sea. The natural water with the plankton community was enriched by nutrients to about winter levels, and to the double of these concentrations. In spring and summer, the phytoplankton responded with rapid uptake of nutrients and an increase in primary production and biomass. In autumn, the uptake of nutrients was also fast, whereas productivity did not increase, and biomass only in diatoms. Not only did the production increase with higher nutrient supply, but also the productive season was prolonged. This fact is of importance for the function of the pelagic system in the Baltic, because the biomass and nutrients remaining after the spring bloom determine to a great extent the productivity of the whole year.

Description: A bioenergetic model was parameterized for herring (Clupea harengus) using information available in the literature. In this model, all components of the energy budget are functions of temperature and fish weight. The model is used to simulate herring growth and consumption in a coastal area of the northern Baltic proper. Simulated seasonal growth curves restrained to fit one weight per age class are similar to observed growth curves, indicating the importance of temperature in determining herring growth rates in the Baltic. Calculated food consumption and conversion efficiencies are compared with other published estimates.

Description: Knowledge of how phytoplankton responds to nutrient inputs is essential for water management and for minimizing eutrophication. Only processes that are deterministic, i.e. that can respond as algorithms, are controllable. The study area is the chain of inshore waters (so-called Bodden) south of the Darss-Zingst peninsula - shallow eutrophic waters of estuarine character in the Southern Baltic. Monitoring programmes and laboratory experiments have revealed an annual periodicity of the phytoplankton and of the physico-chemical factors influencing it. On the basis of these results, experiments were carried out in enclosures to study the effects of nutrient loading on phytoplankton. The purpose was to test the feasibility of influencing phytoplankton development under field conditions during the transition period from late spring to mid-summer. This contribution presents results from the 1985 shallow water enclosure experiments (FLAK 85) which demonstrate that - the scale of phytoplankton reactions and the species involved are stochastic in character and are governed by stochastic interactions between meteorological events and water exchange processes in the chain of Bodden; - all processes affecting phytoplankton growth are deterministic in character, conforming to simple batch theories: simultaneous addition of nitrogen and phosphorus favours green algae, and in exceptional cases one algal species became dominant; - nutrient loadings do not affect the time of transition to the mid-summer phytoplankton population, the most important regulating factor obviously being temperature.

Description: The investigation area, Himmerfjarden Bay situated at the Swedish coast of the northern Baltic Proper, receives waste water from a sewage treatment plant. Phosphorus is efficiently reduced in the sewage treatment resulting in a high N : P ratio (≈ 65 : 1) in the discharge. In the near future also the nitrogen discharge will be reduced, and it is teared that a lowered N : P ratio in the receiving waters may favour an undesired increase of nitrogen fixing blue-green algae. This study is focussed on the development of a common nitrogen fixing species in the area, Aphanizomenon flos-aquae, at varied nutrient loadings in 1983-85. The biomass as well as the number of heterocysts was low near the treatment plant and increased with increasing distance from the sewage discharge. The low biomass and number of heterocysts in Himmerfjarden Bay is interpreted as an effect of competition with other algae and of low level of phosphorus relative to nitrogen, i.e. unfavourable conditions for nitrogen fixation. The abundance of Aphanizomenon was highest in 1984 when the phosphorus load was higher than in the other years of investigation. As a tentative conclusion it is suggested that nitrogen fixing algae may increase as a result of reduction in the nitrogen discharge to Himmerfjarden Bay in the future. At the reference station outside the Bay, nutrient conditions favoured nitrogen fixing algae, as interpreted from an inorganic N:P ratio less than 10:1 during the summers of the investigation period. Here the variation in biomass between the years was mainly due to the variaton in water temperature; Aphanizomenon was most abundant during the warm summer of 1984 and less abundant during the cold summer of 1985. A significant correlation was obtained between the heterocyst frequency and concentration of inorganic phosphorus in the trophogenic layer at the reference station.

Description: In the Bornholm Basin cod eggs occur exclusively in the intermediate and deep water layers, because their buoyancy is insufficient for allowing them to float in the low salinity surface layer. In the lower range of their vertical distribution they can be exposed to low oxygen contents, which might affect their mortality thus influencing recruitment. At three cruises carried out during the main spawning season of cod in the Bornholm region, hydrographic measurements were made and ichthyoplankton samples were taken by means of a Bongo net and a multiple opening/closing zooplankton sampler. In the middle and at the end of May large numbers of cod eggs were found especially in the north-eastern part of the Bornholm Basin, whereas in the middle of June considerable frequencies were observed only in the southeast. The eggs were concentrated at depths of 60 to 75 m, but they occurred also below that depth range down to the bottom. In this lower part of the water column an intermediate minimum of the oxygen concentration was observed with values of less than 1 ml/l. Due to the increase of specific gravity during embryonic development of cod the older egg stages were relatively more abundant in the deeper water, which caused them to be more exposed to low oxygen levels than the younger ones. Instantaneous daily mortality rates (Z} were estimated by comparing the daily production of a given stage during the first survey with that of its corresponding stage during the second survey. For two cohorts the Z-values amounted to 0.314 and 0.322, respectively. An extrapolation for the entire incubation period leads to an overall egg mortality of 99.9 %.

Description: In this study, we evaluate whether it is possible to distinguish the effects of eutrophication from other, i.e. hydrographical, factors affecting zooplankton. We illustrate our arguments with examples from an old set of zooplankton data which includes 9-year records on mesozooplankton and hydrography collected from Seili, off the south coast of Finland. The present study shows that hydrographic changes override or mask, at least in the time period studied, possible eutrophication effects.

Description: Considerable amounts of nutrients enter as a result of human activity the Western Baltic Sea in the form of discharge or seepage from land or as atmospheric input. Benthic macrophytes which preferably inhabit the nutrient recipient shallow near-shore areas, and where they often constitute the major primary producers may thus play an important role in eutrophication processes by uptake and accumulation of nutrient elements, enhanced primary production and following degradation of the produced organic material. Nutrient uptake, binding capacity and limitation as well as nutrient dependent growth of the two community forming seaweeds Phycodrys rubens and Fucus vesiculosus have been investigated and related to the seasonal patterns of the nutrient conditions in their respective habitats. Nutrient concentrations, both phosphorus and nitrogen, in the algal beds are markedly higher than in the surface water of the open Kiel Bight. In general, the seaweeds seem not to be nutrient limited under natural conditions except for nitrogen in Phycodrys during summer. Nutrient tissue contents are saturated only for nitrogen during winter. The significance of these findings is discussed in view of the observed increasing nutrient levels and changes of the vegetation in the Kiel Bight.

Description: To reconstruct the deep-water circulation for the last 3.5 Ma from deep-sea sediments of the eastern equatorial Atlantic, sea floor morphology, sub-bottom reflectors and the echo character have been mapped on the basis of 3.5 kHz records and sediment cores. Physical properties of sediments and synthetic seismograms derived from them enable us to decipher reflector sequences in environments of pelagic, currentresuspended and turbidity sedimentation. The individual reflectors originate from carbonate dissolution, hiatuses, coarse sand layers and interferences. Those which are related to carbonate dissolution and hiatuses provide evidence of water-mass boundaries by their distribution. Five phases of different deep-water circulation can be seen in the record of the last 3.5 Ma, and these are related to climate history: 1. Between 3.7 Ma and 2.2 Ma a strong deep-water circulation indicates a northward flow of bottom water below 4200 m (AABW = Antarctic - Bottom Water) and a southward flow of deep-water above 4200 m (NADW = North-Atlantic Deep Water). 2. Between 1.6 and 1.4 Ma a southward flow of bottom water below 4500 m and a diminished southward flow above 4500 m can be detected. This water-mass geometry can be interpreted by an expansion of the NADW-masses and a displacement of the AABW-masses during the same time. 3. Since 1.4 Ma a northward flow of a bottom-water current developed again. This current flow created a leeside sediment ridge in the southern part of the Kane Gap and furrows in the northern part of it. 4. Beetween 400,000 and 200,000 yrs B. P. the oceanic and atmospheric circulation increased. The strengthened oceanic circulation caused an increase in carbonate dissolution, which is documented by a traceable reflector from 2800 m to 4500 m water depth. At the same time an increase of the atmospheric circulation caused a drastic rise in the pelagic sediment accumulation (〉 100%) through an intensification of upwelling. This runs parallel with a higher oceanic productivity in the northern equatorial divergence zone and an enhanced supply of fluvial and probably eolian sediments from Senegal and Guinea. 5. Before 10,000 yrs B.P. an erosive northward flowing bottom-water current prevailed below 4500 m water depth. After 10,000 yrs B.P. the bottom-water flow was sluggish and non erosive.

Description: Based on the faunal record of planktonic foraminifers in three long gravity sediment cores from the eastern equatorial Atlantic, the sea-surface temperature history over the last 750,000 years was studied at a resolution of 3,000 to 10,000 years. Detailed oxygen-isotope and paleomagnetic stratigraphy helped to identify the following major faunal events: Globorotaloides hexagonus and Globorotalia tumida flexuosa became extinct in the eastern tropical Atlantic at the isotope stage 4/5 boundary, now dated at 68,000 years B.P. The persistent occurrence of the pink variety of Globigerinoides ntber started during the late stage 12 at 410,000 years B.P. CARTUNE-age. This datum may provide an easily detectible fauna! stratigraphic marker for the mid-Brunhes Chron. The updated scheme of the Ericson zones helped the recognition of a hiatus at the northwestern slope of the Sierra Leone Basin covering oxygen-isotope stages 10 to 12. Classifying the planktonic foraminifer counts into six faunal assemblages, according to the factor analysis derived model of PFLAUMANN (1985), the tropical and the tropical-upwelling communities account for 57% at Site 16415, and 86% at Site 13519, respectively of the variance of the faunal record. A largely continuous paleotemperature record for both winter and summer seasons was obtained from the top of the Sierra Leone Rise with the winter temperatures ranging between 20 and 25° C, and the summer ones between 24 and 30° C. The record of cores from greater water depths is frequently interrupted by samples with no-analogue faun al communities and/or poor preservation. Based on the seasonality signal, during cold periods the thermal equator shifted to a geographically more asymmetrical northern position. Dissolution altering the faunal communities becomes stronger with greater water depth, the estimated mean minimum loss of specimens increases from 70% to 80% between 2,860 and 3,850 m water depth although some species will be more susceptible than others. Enhanced dissolution occurred during stage 4 but also during cold phases in the warm stages 7 and 9. Correlations between the Foraminiferal Dissolution Index and the estimated sea-surface temperatures are insignificant. Foraminiferal flux rates, negatively correlated to the flux rates of organic carbon and of diatoms, may be a result of enhanced dissolution during cold stages, destroying still more of the faunal signal than indicated by the calculated minimum loss. The fluctuations of the oxygen-isotope curves and the hibernal sea-surface temperatures are fairly coherent. During warm oxygen-isotope stages the temperature maxima lag often by 5 to 15 ka behind the respective isotope minima. during cold stages, sea-surface temperature changes are partly out of phase and contain additional fluctuations.

Description: Over 100 samples of recent surface sediments from the bottom of the Atlantic Ocean offshore of NW Africa between 34° and 6° N have been analysed palynologically. The objective of this study was to reveal the relation between source areas, transport systems, and resulting distribution patterns of pollen and spores in marine sediments off NW Africa, in order to lay a sound foundation for the interpretation of pollen records of marine cores from this area. The clear zonation of the NW-African vegetation (due to the distinct climatic gradient) is helpful in determining main source areas, and the presence of some major wind belts facilitates the registration of the average course of wind trajectories. The present circulation pattern is driven by the intertropical front (ITCZ) which shifts over the continent between c. 22° N (summer position) and c. 4° N (winter position) in the course of the year. Determination of the period of main pollen release and the average atmospheric circulation pattern effective at that time of the year is of prime importance. The distribution patterns in recent marine sediments of pollen of a series of genera and families appear to record climatological/ecological variables, such as the trajectory of the NE trade, January trades, African Easterly Jet (Saharan Air Layer), the northernmost and southernmost positions of the intertropical convergence zone, and the extent and latitudinal situation of the NW-African vegetation belts. Pollen analysis of a series of dated deep-sea cores taken between c. 35° N and the equator off NW Africa enable the construction of palaeo-distribution maps for time slices of the past, forming a register of palaeoclimatological/palaeoecological information.

Description: Molybdenum and vanadium were analysed in 9 sediment cores recovered from the continental slope and rise off NW Africa. additional chemical and sedimentological parameters as well as isotope stage boundaries were available for the same core profiles from other investigations. Molybdenum, ranging between 〈 1 and 10 ppm, occurs in two associations, either with organic carbon and sulphides in sediments with reducing conditions or with Mn oxides in oxidized near-surface core sections. Highest values (between 4 and 10 ppm Mo) are found in sulphide-rich core sections deposited during glacial times in a core from 200 m water depth. The possibility of anoxic near-bottom water conditions prevailing at this site during certain glacial intervals is discussed. In oxidized near-surface core sections, the diagenetic mobility of Mo becomes evident from strong Mo enrichment together with Mn oxides (values up to 4 ppm Mo). This enrichment is probably due to coprecipitation and/or adsorption of Mo from interstitial water to the diagenetically forming Mn oxides. The close relation between Mo and Corg results in strongly covarying sedimentation rates in both components reaching up to 10 times the rates in glacial compared to interglacial core sections. Vanadium (values between 20 and 100 ppm) does not show clear relations to climate and near-bottom or sediment milieu. It occurs mainly bound to the fine grained terrigenous fraction, associated with aluminium silicates (clay minerals) and iron oxides. Additionally positive covariation of vanadium with phosphorus in most core profiles suggest that some V may be bound to phosphates.

Description: A statistical analysis of 15 deep sea cores in the eastern North Atlantic off NW Africa revealed the typical fluctuation pattern of distinct species groups as has been described from various parts of the world ocean. Only the "WBF-group" appears to be correlated with global climatic changes, i.e. warmer periods as the Eemian and the Atlanticum. A partly antagonistic "High Productivity group" (HPR-group) is in general not linked with global changes but times of increased fertility in the surface water and the resulting flux of organic matter reaching the bottom. The groups were extracted from cluster analysis of more than 150 surface samples (HPR-group, LuTZE & CouLBOURN 1984) and a factor analysis of selected cores (WBF-group). In contrast to previous studies the observed fluctuations can not be explained by drastic changes in bottom water masses, but by the pulsation of a distinct "High Productivity Patch" in space and time. At present, this patch is located below the well known upwelling area between 22° and 12° northern latitude. It shifted to the north (up to 27° N) during the latest glacial period (18 ky), indicating an equivalent shift of upwelling productivity caused by advection of nutrient rich upwelling SACW-waters, probably during most of isotopic stages 2 and 3.

Description: A considerable number of samples recently obtained from the collections of the German research vessels "Meteor" and "Valdivia" in the eastern North Atlantic have been evaluated for their planktonic foraminiferal composition. The new data enabled a quantitative and qualitative improvement of the data base for a statistical analysis of planktonic foraminiferal fauna using the transfer function technique of IMBRIE & KIPP (1971). 134 modern sediment samples from the eastern North Atlantic were selected according to their excellent preservation of foraminifera and treated by a principle component analysis. The resultant six factors account for 96.7% of the variance of the original data comprising 15 major species and species groups. A multiple regression analysis between these factors and the actual mean sea-surface temperatures and salinities resulted in a set of equations. They can be applied for estimating past sea-surface winter and summer temperatures and salinities from planktonic foraminiferal assemblages for approximately the last 500,000 years. The new functions have a standard error of 1.2° C for winter and summer temperature and 0.4‰ for annual salinity.

Description: Sedimentological and geotechnical analyses were carried out on two undisturbed large diameter deep sea cores from the Antarctic sector of the Atlantic ocean. One core, from a silled basin within the Bransfield Strait is characterized by fine grained hemipelagic material and turbidite layers. The other core, from the continental slope of the Weddell Sea represents a typical glacial marine environment. The variations of physical properties as related to both an increasing overburden pressure (or depth below top of core) and/or to lithological changes are discussed. With increasing overburden pressure only small variations of physical properties were observed. In core 14882-2 the porosity decreases 0.7% per meter, the natural water content 6% per meter. The wet bulk density and the shear strength increase with rates of 0.015 g/cm3 and 0.5 KPa per meter. Compared to small variations in consolidation, the changes of the lithology cause more extreme variations of physical properties: e.g. decreases the natural water content by 100%, the porosity by 14%, and the wet bulk density increases by 0.23 g/cm3 due to a turbidite layer in the core from the Bransfield Strait (core 14882-2). In the core from the continental slope of the Weddell Sea (core 14875-1) two major unconformities have been detected. The ice-rafted debris of this core causes a generally lower porosity (64%), a lower natural water content (75%), a higher wet bulk density (1.55 g/cm3) and specific grain density (2.62 g/cm3), compared to the core from the Bransfield Strait (porosity 77% , natural water content 151% , wet bulk density 1.34 g/cm3, specific grain density 2.47 g/cm3).

Description: The "Meteor" cores 22M36 and 22M37 are situated on the eastern rim of the Mediterranean Ridge SW of the Peloponnesus at 3200 and 3350 m water depth. Core 22M37 contains a breccia consisting mainly of Upper Serravallian/Lower Tortonian claystone clasts. They are characterized by smectite-dominated clay mineral assemblages. The breccia contains displaced benthic foraminifers of neritic character and bryozoan debris. At the top of the breccia follows a chaotic stratigraphic sequence including Serravallian (?), Tortonian, Messinian, Pliocene and Pleistocene sediments. The deposits of Upper Tortonian to Pleistocene age are characterized by illite-dominated clay mineral assemblages. The smectite-dominated assemblages are very similar to that of the surface sediments from the extreme eastern part of the Levantine Basin which represent Nile-derived terrigenous material. It is speculated, that during Upper Serravallian/Lower Tortonian time mineral detritus derived from an early "Nile" may have been transported into the Ionian Sea. This would implicite a seafloor morphology different from today's (the Mediterranean Ridge prevents sediment transport into the Ionian Sea) and considerable tectonic movements since that time. The termination of the smectitedominated sedimentation in the considered area SW of the Peloponnesus would indicate the beginning of the barrier function of the Mediterranean Ridge. Such movements have to be inferred also from the neritic components of the breccia. They have to be explained by turbiditic influx. However, in the present morphology, turbidity currents starting from a shallow water region could not reach the core positions. Core 22M36, situated close to core 22M37, represents a Quaternary sequence (upper part of nannoplankton zone NN 19 to base of NN 21) with conglomeratic layers and unconformities. They point to tectonic movements within this time. The origin of the breccia as well as of the chaotic sequence in core 22M37 may have happened near the boundary of nannoplankton zones NN 19/20.