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: Neben Evertebratenplankton und Jungfischen anderer Arten wurden 25 Myctophiden der Art Centrobranchus nigroocellatus im April und Juli 1967 im Seegebiet westlich und südwestlich von Madeira mit einem Neustonnetz gefangen. 21 C. nigroocellatus hatten ausschließlich Mollusken, davon 18 nur die Gastropoden Styliola subula und Atlanta peroni gefressen. Der Myctophide und die Gastropoden steigen zeitweise in die 0-10 cm-Mikroschicht auf: Sie sind nachtpositiv mit Betonung der Abenddämmerung bei S. subula, mit Betonung der Morgendämmerung bei Atlanta peroni und mit Betonung wahrscheinlich beider Dämmerungen bei C. nigroocellatus. Der Myctophide zeigt mit der Nahrungsspezialisierung zusammenhängende morphologische Besonderheiten. With a neuston-net 25 Centrobranchus nigroocellatus were collected west of Madeira during April and July 1967. The guts of 18 myctophids contained exclusively the gastropods Styliola subula, Atlanta peroni, or both of them. The myctophid and both of the gastropods were found in the 0-10 cm-microlayer at night. S. subula was most abundant at dusk, A. peroni at dawn, whereas C. nigroocellatus was caught most frequently during dusk and dawn. Adaptions of the myctophid are discussed.

Description: Die Sonnenkompaßorientierung des Amphipoden Orchestia platensis läßt sich durch einen Wechsel der Umgebungstemperatur beeinflussen; kurz nach einem Temperatursprung prägt sich die Änderung der Fluchtrichtung am stärksten aus. Die Orientierung warm- und kaltgehaltener Krebse unterscheidet sich auch, wenn die Adaptation mehrere Tage lang bei einer konstanten Photoperiode vorgenommen wird. Tiefe Versuchstemperaturen verstärken die phototaktische Komponente bei den Richtungswahlen, sehr tiefe lassen die Krebse landeinwärts fliehen. Eine mögliche Kompensation der Temperaturwirkung auf den Lauf der inneren Uhr ist bei Orchestia nicht an ein gleichsinniges Anpassen des Stoffwechsels gebunden; der Sauerstoffverbrauch der Krebse zeigt nämlich keine Leistungsadaptation. In the amphipod Orchestia platensis sun-compass orientation is affected by changes in ambient temperature, a short time after sudden transitions in temperature deviations in normal behaviour of escape became apparent. There are differences in solar orientation of warm- and cold adapted amphipods, even if the acclimation is performed under constant photo periods. Low temperatures intensify the positiv phototactic tendency; at very low temperatures the amphipods try to excape towards the land. The possible ability to compensate temperature-induced variations of the endogenous clock seems not to be controlled by a metabolic acclimation, as the oxygen consumption of Orchestia shows no capacity adaptation.

Description: In der Oberen Eider bei Rendsburg wurden erstmals folgende Bryozoen-Arten gefunden: Bulbella abscondita BRAEM, Tanganella mülleri (KRAEPELIN), Bowerbankia gracilis LEIDY und Conopeum seurati (CANU). Die letztgenannte Art wurde mit einem Fund im Nordostseekanal 1965 zum ersten Mal in deutschen Gewässern nachgewiesen. Eine minierende Wuchsform (forma perforans) wurde erstmals von Tanganella mülleri in verwittertem Holz in der Oberen Eider gefunden. Bowerbankia gracilis (Vesicularina) bildet Dauerknospen (wie die Arten der Paludicellea, z.B. Bulbella abscondita und Tanganella mülleri), die in die morsche Oberflächenschicht des Holzes eingesenkt werden können. Bulbella abscondita und Tanganella mülleri minieren, indem sich die wachsenden Knospen durch das morsche Holz pressen. Diese Arten haben stellenweise einen deutlichen Anteil an der Entstehung der Verwitterungsrinde an Holz im Brackwasser (und vermutlich auch im Süßwasser). Durch ihre lokal große Siedlungsdichte und durch die anscheinend weite Verbreitung können die minierenden Bryozoen als Schädlinge an Wasserbauten aus Holz auftreten. The following Bryozoan species have been found for the first time in the Obere Eider near Rendsburg: Bulbella abscondita BRAEM, Tanganella mülleri (KRAEPELIN), Bowerbankia gracilis LEIDY, and Conopeum seurati (CANU). The occurence of the latter in German waters was first ascertained by a find in the Nordostseekanal in 1965. A penetrating growth (forma perforans) was found for the first time for Tanganella mülleri in rotten wood in the Obere Eider. Bowerbankia gracilis (Vesicularina) builds lasting buds (as known from the Paludicellea, for example Bulbella abscondita and Tanganella mülleri), which may penetrate the rotten surface layer of the wood. Bulbella abscondita and Tanganella mülleri grow penetrating by pressing the buds through the rotten wood. Sometimes these species no doubt help to decompose the wood in brackish water (and probably also in fresh water). These penetrating Bryozoans, which show a great lokal density and are probably widely distributed, may threaten wood constructions in water.

Description: Es wird ein Gerät zur gleichzeitigen analogen Registrierung und digitalen Aufzeichnung von Sauerstoffpartialdruck, Temperatur und Tiefe beschrieben. Es werden Angaben über die Konstruktion, die Funktion und über die Handhabung sowie Eichung der Sonde gemacht. An apparatus for the simultaneous and analog record of the oxygen tension, the temperature and the depth is described. Details of the construction, the function, the treatment, and of the calibration of the oxygen probe are given.

Description: Es werden die Ergebnisse von Temperatur- und Salzgehaltsmessungen auf einem hydrographischen Schnitt durch die westliche Ostsee im Januar l968 im Hinblick auf Erneuerungsvorgänge im Tiefenwasser des Arkonabeckens diskutiert. Bei den Messungen wurde besonderer Wert auf hohes Auflösungsvermögen der Beobachtungen hinsichtlich der Tiefe (Meßwertabstand 40 cm), des Stationsabstandes (2 sm) und der Zeit (mittlere Schiffsgeschwindigkeit 7 kn) gelegt. Sie zeigen sowohl advektive als auch konvektive Erneuerungsprozesse in sehr begrenzten räumlichen Ausdehnungen im Bereich des Tiefenwassers mit charakteristischen Dimensionen von 6 sm in der Horizontalen und 7 m in der Vertikalen. Man kann deshalb die Menge des erneuerten Tiefenwassers nicht alleine aus einer Bilanz des Ein- uncl Ausstroms im Fehmarnbelt erhalten. Um die für die Erneuerung maßgebenden Ausbreitungs-, Konvektions- und Vemischungsvorgänge zu erfassen sind außerdem sehr engabständige Messungen im Arkonabecken selbst notwendig.

Description: 30 Harpacticoidenarten wurden im lenitischen Watt und in den Salzwiesen der deutschen Nordseeküste gefunden. Die Beschreibung von vier Arten (Microarthridion fallax, M. littorale, Amphiascoides debilis, Enhydrosoma gariene) wird ergänzt. Amphiascoides limicola wird als Synonym von A. debilis angesehen. Von Stenhelia palustris wird der Wohnröhrenbau beschrieben. 30 species of harpacticoids were found in mud flats and salt marshes (Spartina townsendii, Puccinellia maritima, Festuca rubra) on the western coast of Germany. Additional details to the description of four species (Microarthridion fallax, M. littorale, Amphiascoides debilis, Enhydrosoma gariene) are presented. Amphiascoides limicola is considered to be synonym with Amphiascoides debilis. Living tubes of Stenhelia palustris are described.

Description: An 42 weiblichen Kabeljau mit den Längen 58 - 94 cm, 54 Schellfischen aus zwei Populationen mit den Längen von 39,0 - 53,8 und 53 - 69 cm und 30 Heringen von 29,8 - 39,0 cm Länge wurden Eizählungen durchgeführt. Die Eizahlen sind zu Länge und Gewicht, und zum Teil zum Alter, in Beziehung gesetzt und die Ergebnisse in Diagrammen und Regressionsgleichungen dargestellt. Beim Kabeljau wurden Eizahlen von 0,5 - 5,4 Mill., beim Schellfisch 0,18 - 0,65 und 0,45 - 1,64 Mill. und beim Hering 29000 - 184000 ermittelt. Bei gleicher Länge und gleichem Gewicht kann die Eizahl um das zwei- bis dreifache variieren. Die Eiproduktion setzt beim isländischen Kabeljau frühestens im Alter von 4 Jahren bei 50 cm ein und erhöht sich um 84400 Eier/cm. Bei den beiden Schellfischpopulationen setzt die Eiproduktion frühestens mit 4 Jahren bei 30 bzw. 36 cm Länge ein und erhöht sich um 20800 bzw. 41600 Eier/cm. Der Hering ergab ab 26 cm Länge eine Zunahme von 9290 Eiern/cm. Eggs were counted in 42 female cod, 58 - 94 cm in length, 54 haddocks of two different populations, 39,0 - 53,8 and 53 - 69 cm in length, and 30 herrings, 29,8 - 39,0 cm in length. The egg numbers were correlated to length and weight, and partielly to age of fish. The results are presented in graphs and regression equations. For the cod, egg numbers of 0,5 - 5,4 Mill. were obtained, for haddock 0,18 - 0,65 and 0,45 - 1,64 Mill. and for herring 29000 - 184000. The fecundity varies by a factor 2 - 3 for the same length and weight. The egg production of the cod starts with an age of 4 years and at a length of 50 cm, it increases about 84400 eggs/cm. In the haddock egg production starts at 30 and 36 cm representively, and with an age of 4 years, it increases to 20800 and 41600 eggs/cm. The eggproduction of the herring, starts at a length of 26 cm, it increases about 9290 eggs/cm.

Description: In deutschen Meeresgebieten und Brackwässern wurden erstmals nachgewiesen: Crisia aculeata HASSALL (Helgoland, ? "Lister Rhede"), Electra monostachys (BUSK) (Weser-Mündung, N von Wangerooge, Schleswig-Holsteinische Austernbank), Conopeum seurati (CANU) (Nordostseekanal, Kieler Förde), Callopora dumerilii (Aunoum) (Helgoländer Tiefe Rinne). Buskia nitens ALDER wurde in der Kieler Bucht und bei Helgoland gefunden. Aetea truncata (LANDSBOROUGH) wurde erstmals in der Kieler Bucht nachgewiesen. Bei Helgoland wurde eine nicht bestimmte Crisia gefunden. Electra monostachys kann (vermutlich durch saure Sekrete) auf kalkigem Substrat "Spuren" bilden in Form von Verfärbungsflecken oder kleinen länglichen Gruben unter der Mitte der Cystide. The following species have been found for the first time in German marine and brackish waters: Crisia aculeata HASSALL (Helgoland, ? "Lister Rhede"), Electra monostachys (BUSK) (Weser-Mündung, N of Wangerooge, Schleswig-Holsteinische Austernbank), Conopeum seurati (CANU) (Nordostseekanal, Kieler Förde), Callopora dumerilii (Aunoum) (Helgoländer Tiefe Rinne). Buskia nitens ALDER has been found in the Kieler Bucht and around Helgoland. Aetea truncata (LANDSBOROUGH) is new in the Kieler Bucht. An undetermined Crisia has been found near Helgoland. Electra monostachys is able to produce coloured markes and sometimes small excavations (possible by acid secretions) in the carbonate substrate under the cystids.

Description: Auf einer Ankerstation des F. K. "Alkor" vom 6.-12.9.1967 in der mittleren Ostsee im Gotland-Tief wurden signifikante chemische Parameter (gelöster Sauerstoff, Nitrat, Nitrit, gelöstes anorganisches Phosphat, Ammoniak, Silikat, ph-Wert, Alkalinität) in schneller Folge aus 12 Tiefenhorizonten entnommen und automatisch analysiert. Außerdem wurde Schwefelwasserstoff zwischen 170 m und 200 m Tiefe angetroffen und in den Tiefen 175 m und 200 m fortlaufend gemessen. Parallel zu diesen Messungen registrierten 5 Richardson-Strommesser, die in einer Meßkette in 500 m Entfernung von der Ankerstation verankert waren, in 5 verschiedenen Tiefen die Strömung mit einer Meßwertfolge von 2 bzw. 5 min. Das Ziel der Untersuchung war, die Veränderlichkeit chemischer Größen im Gotland-Becken stichprobenartig aufzunehmen. Die Strömungsmessungen dienten dem Zweck, die physikalisch gegebene Veränderlichkeit zu erfassen und in Zusammenhang mit Änderungen der chemischen Parameter zu bringen. Anhand des gewonnenen Beobachtungsmaterials läßt sich für einige charakteristische chemische Größen die Verteilung im Raum bestimmen, die auf Grund von Bahnintegrationen in den Meßtiefen der Strömung ausschnittsweise ermittelt wird. Die Integration führt nur für die Wasserschichten unterhalb von 90 m Tiefe zu ausreichend gesicherten Ortsangaben, da dort die horizontale Versetzung der Wasserteilchen erheblich geringer als in Oberflächennähe ist, wo die an einer Meßstelle erhaltene Information über die großräumige Verteilung der Strömung nicht ausreicht. Es zeigt sich, daß in den unteren Wasserschichten charakteristische Größen wie z. B. anorganisches Phosphat, Nitrat, Sauerstoff und Schwefelwasserstoff zeitliche Änderungen in einem Horizont erfahren, während hingegen Salzgehalt und Temperatur von diesen Änderungen nicht betroffen sind. Die räumliche Variabilität der ausgewählten chemischen Größen äußert sich in wolken- oder fleckenartig zusammenhängenden Felder erhöhter oder verminderter Konzentration, die verhältnismäßig scharf abgesetzt nebeneinander in den einzelnen Tiefenhorizonten auftreten. Mittlere großräumige Änderungen erhalten dadurch eine sehr unruhige Feinstruktur. Aus den vorliegenden Beobachtungen ergeben sich für die fleckenhaft verteilten Schwankungen im Bereich des Gotland-Tiefs Horizontalerstreckungen von wenigen 100 Metern bis zu wenigen Kilometern. Die Meßergebnisse reichen nicht aus, um die vorgefundene kleinräumige Veränderlichkeit eindeutig biologischer Aktivität zuzuschreiben.

Description: Es wird ein Überblick über die zur Zeit bekannten physikalischen Prinzipien zur Messung von Strömungsverteilungen im Meer unter besonderer Berücksichtigung der Verhältnisse in Küstennähe gegeben. In dieser Zusammenstellung sind neben den Euler'schen Meßverfahren auch die wichtigsten Bahnlinienmethoden zur Untersuchung kleinräumiger Stromverteilung enthalten, obwohl sie bisher kaum Anwendung im Meer gefunden haben. Über die physikalischen und technischen Grenzen der aufgeführten Methoden wird an anderer Stelle berichtet. A review of physical principles of measuring currents is presented with respect to the application to measurements of near-shore orbital velocities. Because of the great number of principles this paper gives a survey whereas a discussion of the physical and technical restrictions of these techniques will be published later.

Description: Ausgehend von Strömungsmessungen in der Nähe des Gotland-Tiefs bei φ = 57°20'N, λ = 20°3'E vom 6.9. - 12.9.1967 werden die Veränderungen im zeitlichen Ablauf und vertikalen Aufbau des Strömungsfeldes untersucht. Mit Hilfe der Registrierungen von 5 RICHARDSON-Strommessern, die getrennt vom Schiff in einem eigenen Verankerungssystem in den Tiefen 18 m, 43 m, 94.5 m, 144.5 m und 205 m senkrecht übereinander ausgelegt waren, ergibt sich folgendes Bild über die Veränderlichkeit der Strömung im Periodenbereich zwischen 4 Minuten und 15 Stunden: In allen Tiefen bildet eine langperiodische Schwingung der Periode von etwa 13,5 h, die unterhalb der örtlich gegebenen Trägheitsperiode von 14 h 13 min liegt, den beherrschenden Teil der Veränderlichkeit. Die Amplituden nehmen von einem Wert von 20 cm/sec in Oberflächennähe auf etwa 2 cm/sec in mittleren Tiefen ab und vergrößern sich in Bodennähe wieder auf einen Wert von 4-5 cm/sec. In vertikaler Richtung treten auf kurzer Distanz verhältnismäßig hohe Phasendifferenzen im Bewegungsablauf auf. So ist z.B. auf 60 m Tiefendifferenz zwischen 144.5 m und 205 m eine Phasenverschiebung von nahezu 180° über den gesamten Beobachtungszeitraum gegeben. Einen erheblichen Einfluß hat neben der langperiodischen Variation die kurzperiodische innere Unruhe. Mit maximalen Amplituden von 2 - 3 cm/sec sind kurzperiodische Schwingungen im Periodenbereich zwischen 6 min und etwa 1 h in der Deckschicht und in mittleren Tiefen am stärksten ausgebildet. Zeiträume erhöhter Intensität werden wiederholt für mehrere Stunden unterbrochen, in denen die Aktivität kurzperiodischer Bewegungen vermindert ist. Die Spektralanalyse der Meßreihen führt zu dem Ergebnis, daß die kurzperiodischen internen Schwingungen häufig in einer 100 m mächtigen Schicht, gemessen von der Oberfläche ab, zusammenhängend ablaufen und daß in mehreren Einzelfällen die gesamte Wassersäule in die Bewegungen einbezogen ist. In einer theoretischen Betrachtung über die Entstehung und die horizontalen Ausdehnungen der beobachteten Wellenbewegungen zeigt sich, daß die kurzperiodische Unruhe im Gotland-Becken Wellenlängen zwischen etwa 100 m und mehreren Kilometern aufweist und durch kurze Zeit andauernde Kräftefelder von entsprechender horizontaler Ausdehnung erzeugt werden kann. Die Ursachen sind in Inhomogenitäten im mittleren Strömungsfeld und entsprechend kleinräumigen Druck- oder Windschwankungen der Atmosphäre in Oberflächennähe zu suchen. Für die langperiodischen Bewegungen ergibt sich eine wesentlich größere Ausdehnung. Die Erzeugung und Verbreitung der Störungen setzt ein Kraftefeld von 50 km und größeren Werten an horinzontaler Erstreckung voraus. Die Bewegungen erfassen somit sämtliche Teile der Gotlandsee fast gleichzeitig. Die Dauer der Anregung kann sich auf wenige Stunden beschränken und läßt sich in direkten Zusammenhang mit Starkwindfeldern über der zentralen Ostsee bringen. Die Häufigkeit stürmischer Wetterbedingungen über der Ostsee hat zur Folge, daß die langperiodische Veränderlichkeit der Schichtung und Strömungsverteilung im Gotland-Becken nur selten auf verschwindend kleine Werte abklingt.

Description: Die beschriebene Methode gestattet das Homogenisieren des Phytoplanktons, das Extrahieren des Chlorophylls und das daran anschließende Zentrifugieren auch bei kleinsten Probenmengen in ein und demselben abgeschlossenen Gefäß. Die so erzielte Chlorophyllausbeute ist höher als die herkömmlicher Methoden. In ihrer Wirksamkeit verglichen wird die vorgeschlagene Methode mit der 18-stündigen Extraktion ohne Vorbehandlung des Phytoplanktons und mit der 15-minütigen Extraktion nach voraufgegangenem "Grinding"; dabei wird der Grad der Homogenisation und Extraktion über den photometrisch gemessenen Chlorophyll-a-Gehalt und eine fluoreszenzmikroskopische Analyse des extrahierten Sediments kontrolliert. A method is described, which allows the homogenisation of phytoplankton, the extraction of chlorophyll, and the centrifugation of even the smallest samples in a stoppered glass tube. The yield of this method is higher than that of any other known method for the determination of chlorophyll. The effectiveness of the proposed method is compared with the 18 hours extraction method without any preliminary treatment of the phytoplankton and with the so called "grinding method". In this comparison the rate of homogenisation and extraction ist controlled for all three methods by the photometric measurement of the chlorophyll a content and by the fluorescence microscopical analysis of the extracted sediment.

Description: Gesetzmäßigkeiten fur die jahreszeitliche und regionale Verteilung von Agrobacterium stellulatum und A. ferrugineum wurden durch Vergleich ihrer Bakterienzahlen mit verschiedenen biotischen und abiotischen Faktoren gesucht. Für ihre Verbreitung ergab sich eine starke Abhängigkeit vom Salzgehalt. Im Wasser der Ostsee und des südlichen Kattegat werden sie zwischen 7 und 33 ‰ angetroffen, in der nährstoffreichen Schlei bis hinunter zu 2 ‰. Die jahreszeitliche Häufigkeit ist durch ein ausgeprägtes Herbst/Winter-Maximum und ein schwächeres Frühsommermaximum gekennzeichnet und weist eine starke Parallelität zur Gesamtkeimzahl auf. Auf Algen sind in erster Linie andere Agrobacterium-Arten anzutreffen. The seasonal and regional distribution of Agrobacterium stellulatum and A. ferrugineum was studied by comparing their bacterial counts with several biotic and abiotic factors. It was found that their spreading greatly depends upon salinity. In water of the Baltic and of the Southern Kattegat they occur between 7 and 33 per mille, in the eutrophic Schlei down to 2 ‰. Their seasonal distribution shows a distinct peak between autumn and winter an a weaker peak at the beginning of summer and strongly parallels total counts. Agrobacteria found on algae mostly belong into species different from A. stellulatum and A. ferugineum.

Description: The distribution of the particulate organic carbon and nitrogen, and of the dissolved organic carbon as a function of depth and of time is investigated. A common pattern of these distributions is found with certain deviations from a mean value. The ratio N/C (particulate) is calculated. The variation of this parameter with depth shows a maximum at 10 m depth indicating increased biological activity. Also calculated are the ratios and the correlation coefficients between the concentrations of dissolved and particulate organic carbon and between the protein content of the particulate organic matter and its organic nitrogen content. Conclusions on the biochemistry of the phytoplankton are drawn from these computations. Die Veränderlichkeit der Konzentration an partikularem organischen Kohlenstoff und Stickstoff und gelöstem organischen Kohlenstoff mit der Tiefe und mit der Zeit werden untersucht. Die Veränderlichkeit dieser Parameter mit der Tiefe hat zu verschiedenen Zeiten ein ähnliches Aussehen mit gewissen Abweichungen von einem Mittelwert. Das Verhältnis N/C der partikulären Substanz wurde berechnet. Die Tiefenverteilung dieses Parameters hat ein Maximum in 10 m Tiefe, das erhöhte biologische Aktivität anzeigt. Ebenfalls berechnet werden die Verhältnisse zwischen den Konzentrationen von partikularem und von gelöstem organischen Kohlenstoff und der Korrelationskoeffizient zwischen beiden Größen. Die gleichen Berechnungen werden angestellt mit dem Proteingehalt der partikulären Substanz und ihrem Gehalt an organisch gebundenen Stickstoff. Aus diesen Berechnungen werden Schlüsse gezogen über die Biochemie des Phytoplanktons.

Description: The results of five cruises between April 1966 and April 1967 through the Suez Canal and its lakes showed that the prime factor for the reversal of the northerly current in the summer season must be the wind stress on the water and not as previously thought to be caused by the effect of the Nile flood. The new seasonal variation after the completion of the Aswan High Dam is discussed. Fünf hydrographische Aufnahmen des Suez-Kanals im Zeitraum April 1966 April 1967 ergaben, daß die sommerliche Umkehr des sonst herrschenden Nordstromes auf die Wirkung des Windes zurückzuführen ist. Vor Beendigung des Assuan-Staudammes war die Nilflut als Ursache dafür angesehen worden. Weiterhin werden die jahreszeitlichen Schwankungen nach Fertigstellung des Dammes diskutiert.

Description: In den oberen 75 Metern Wassertiefe wurden neben dem Auszählen der Planktonorganismen chemische Nachweise durchgeführt auf Chlorophyll, Protein, RNA und die Gesamtheit einiger vorkommender Zucker. Diese und andere schon vorliegende Daten wurden auf ihre Aussagefähigkeit über die partikuläre Substanz und das lebende Plankton untersucht, um daran anschließend die Beziehungen zwischen den als aussagekräftig erkannten Werten herzustellen. Die damit ermöglichte Beschreibung des Planktonbestandes gestattet dann zwar die Konstatierung eines tiefenabhängigen, unterschiedlichen physiologischen Zustandes dominierender Organismen, doch werden hierbei auch die Aussagegrenzen summarisch-chemischer Bestimmungsmethoden sichtbar. The investigations were limited to the upper 75 meters. Here besides a counting of plankton organisms chemical determinations were performed for chlorophyll, protein, RNA, and the total amount of some occuring sugars. These and other data were compared as to their accuracy in estimating particulate matter and living organisms. Then it was searched for the relationship between values of recognized reliability. The resulting estimation of the plankton-stock permits the recognition of a varying physiological state of dominant organisms, depending on depth, though the limits of an account, given by chemical analysis of the entire amount of particulate matter, are reached.

Description: Der vertikale turbulente Diffusionskoeffizient Kz wurde aus der mittleren Salzgehaltsverteilung und einem mittleren Stromprofil berechnet. Die dazu erforderlichen Daten konnten durch die wiederholte Aufnahme von vertikalen Salzgehalts- und Stromprofilen an ausgewählten Positionen gewonnen werden. Diese Daten geben fur den betrachteten Zeitraum die mittleren Verhältnisse in dem untersuchten Seegebiet wieder. Von früheren Bestimmungen des Diffusionskoeffizienten, die auf Punkt- oder Einzelmessungen beruhten, unterscheidet sich die hier zur Anwendung gekommenen Methode zur Bestimmung von Kz durch die Anlage der Messungen. Das betrifft sowohl die Anordnungen der Stationen, als auch die Zahl der Messungen und die Möglichkeit der kontinuierlichen Registrierung von Temperatur, Salzgehalt und Strömung. Bei der Diskussion der Ergebnisse der vorliegenden Arbeit wurde der gemessene Zusammenhang zwischen dem Diffusionskoeffizienten und der Richardson-Zahl den tbeoretischen Beziehungen zwischen dem Diffusionskoeffizienten und der Richardson-Zahl von MUNK und ANDERSON (1948) und MAMAJEV (1958) gegenübergestellt. Es ergab sich: Beide Formeln sind im Rahmen der Meßgenauigkeit gleich gut zur Beschreibung des Zusammenhanges zwischen Diffusionskoeffizienten und Richardson-Zahl geeignet. In Oberflächennähe ist nur eine angenäherte Übereinstimmung zwischen dem theoretisch vorhergesagten und der gemessenen Abhängigkeit von Kz und Ri vorhanden. Dagegen findet man eine gute Annäherung der gemessenen Werte mit der Theorie im Bereich großer Diffusionskoeffizienten. The vertical eddy-diffusion coefficient Kz was computed from the mean salinity-distribution and current profiles. The data were obtained from repeated vertical profiles of salinity and currents at selected positions. The method applied here for determinating the eddy-diffusion coefficient, differs from older ones which use individual measurements only, mainly in three points: the special arrangement of the stations (triangel), a great number of measurements and the continous registration of temperature, salinity, and current. In this work the relations between Kz and Ri (Richardson-Number) as measured are compared with the theoretical correlations between Kz and Ri obtained by MUNK and ANDERSON (1948) and MAMAJEV (1958). It is shown that both formulas describe the connection between the above mentioned parameters equally well. Near the surface the predicted relation between Kz and Ri corresponds only approximately to the measured one. In the range of large diffusion-coefficients the measured values fit well to the theoretical curves.

Description: The present study was undertaken to investigate the physical and chemical variability in the eastern Gotland Basin. This can serve as an example for the variability in the inner part of an adjacent sea with small tidal influence. Two anchor stations of about four days duration were made, with R.V. "Alkor" in September 1967 and with F.R.V. "Anton Dohrn" in May 1968. On the basis of variations in the physical parameters, and also from continuous recordings of salinity and temperature, c.f., of oxygen and temperature, the presence of internal waves is demonstrated. The variability in the chemical data not only indicate internal waves but also proves the patchlike structure of the water masses with regard to biochemical parameters. The two anchor stations were made during periods of partial and of total stagnation in the deeper parts of the Gotland Basin. Ziel dieser Arbeit ist eine Beschreibung der physikalisch chemischen Veränderlichkeit im östlichen Gotland-Becken, und zwar als Beispiel für die Veränderlichkeit im inneren Teil eines gezeitenarmen Nebenmeeres. Zwei viertägige Ankerstationen wurden durchgeführt, im September 1967 und Mai 1968, mit "Alkor" und "Anton Dohr". Auf Grund der Variationen in den physikalischen Parametern und auch von den kontinuierlichen Registrierungen von Salzgehalt und Temperatur, bzw. von Sauerstoff und Temperatur, werden interne Wellen nachgewiesen. Von der Veränderlichkeit der chemischen Parameter werden neben internen Wellen auch wolkenartige Strukturen der Wassermassen im Bezug auf biochemische Eigenschaften demonstriert. Beide Dauerstationen fielen in einer Periode von teilweiser und von voller Stagnation im Gotland-Becken.

Description: An Pilzen der Gattung Thraustochytrium wurde starker Befall durch den Myxomyceten Labyrinthula beobachtet und es wird angenommen, daß es sich hierbei um eine Form von Parasitismus handelt. There has been observed strong attack - probably parasitic - of Thraustochytrium spec. by the myxomycete Labyrinthula.

Description: Die Muskelsysteme der im selben Biotop (Weichboden) lebenden Pontogenia chrysocoma (Aphroditidae), Thalenessa stylolepis (Sigalionidae), Glycera tesselata ( Glyceridae), Arabella iricolor und Lumbrineris fragilis (beides Eunicidae sens. lat.) zeigen deutliche Unterschiede. Sie weisen jedoch große Ähnlichkeit mit den Muskelsystemen anderer Arten auf, mit denen sie in eine Gattung oder Familie gehoren, wenn diese auch in anderen Biotopen vorkommen. Der Lebensraum modifiziert die Muskelsysteme also nur geringfügig. The muscle systems of Pontogenia chrysocoma (Aphroditidae), Thalenessa stylolepis (Sigalionidae), Glycera tesselata (Glyceridae), Arabella iricolor and Lumbrineris fragilis (Eunicidae sens. lat.), all of which inhabitate the same biotope (soft bottom) exhibit distinct differences. They show, however, always great similarities with the musculature of related species of the same genus or family, which frequently are living on completely different substrates. Therefore, it is concluded that the biotope has a negligible modifying effect on the muscle system.

Description: Es werden sieben Formen Niederer Pilze (THRAUSTOCHYTRIACEAE, SAPROLEGNIALES) neu für das Gebiet der westlichen Ostsee beschrieben und ihre Verbreitung sowie ihr Verhalten gegenüber Salzgehalt, Temperatur und Abwasserbelastung untersucht. Es handelt sich um euryhaline, eurytherme Saprophyten mit einer gewissen Resistenz gegenüber Abwasserbelastungen. - Unterschiede in der Artenzusammensetzung gegenüber Funden von der Nordseeküste waren nicht festzustellen. Zwei Formen wurden auch östlich der Darßer Schwelle (im Arkona- und Bornholmbecken) gefunden. Chytridiale Phycomyceten wurden kaum beobachtet. Seven forms of Lower Fungi (THRAUSTOCHYTRIACEAE, SAPROLEGNIALES) are discribed new for the western Baltic. Their occurrence as well as their response towards salinity, temperature, and pollution have been studied and the results suggest that the fungi described are euryhaline, eurytherme saprophytes with some ability to overcome pollution charges. - Differences in respect to the occurrence of species in the western Baltic and the North Sea respectively have not been observed. Two forms have been found east of the Darß shelf (in the Arkona and Bornholm basin). Phycomycetes of the order Chytridiales have rarely been observed.

Description: Along three sections and al a one day permanent station chemical parameters (P04, Si04, N02, N03, NH3, and 02) were determined from NANSEN bottle samples. Significant fluctuations of some of these parameters were observed. From a moored current meter array the current field was determined. It was coupled to the concentrations observed at the permanent station. The horizontal gradients of chemical components showed values up to 50% in less than 500 m distance. By use of the diffusion theory some estimates on the time scale of biochemical processes are presented. From the entire set of about 400 observations the mean relation between phosphate and silicate was found to be linear. Nitrate seemed to be the growth limiting factor. The mean relations between phosphate and nitrate and silicate and nitrate respectively differ considerably from a linear function. The oxidative ratios for nitrate, phosphate and silicate have been calculated and the following combination has been found from these regressions: ΔAOU : ΔP : ΔN : ΔSi = 276 : 1.2 : 14.7 : 7.2

Description: Die Teilchengrößenanalyse van Detrituspartikeln mit dem Teilchengrößenanalysator TGZ 3 der Firma Zeiss wird ausführlich beschrieben. Nach dieser Methode wurden insgesamt 92 Wasserproben von 6 Stationen in der westlichen Ostsee untersucht und eine Gesamtverteilungskurve für alle Detritusteilchen gebildet. In dem untersuchten Größenbereich zwischen 8 und 60 µ wurden die folgenden Mittelwerte gefunden: Teilchengröße: 17.6 ± 6.5 µ., Teilchenzahl: 1.35 Mill./l, Teilchenvolumen: 5.68 mm3/l, Teilchenoberfläche: 14.91 cm2/l. Es wird gezeigt, daß unter gewissen Voraussetzungen aus der Teilchengrößenverteilung das Detritustrockengewicht einer Wasserprobe errechnet werden kann. Die gewonnenen Ergebnisse werden mit den Detrituswerten verglichen, die aus den gleichzeitig ausgeführten chemischen Analysendaten durch die Differenzbildung Sestongewicht - Planktongewicht (nach dem Eiweiß- und Chlorophyllgehalt) = Detritusgewicht erhalten wurden. The analysis of the size distribution of detritus particles by means of the 'Teilchengrößenanalysator TGZ 3, Fa. Zeiss' is described in detail. 92 water samples collected at 6 stations in the western Baltic were analysed by this method. A total size spectrum for all counted particles is formed. in the investigated size group ranging from 8 to 60 µ average values were found as follows: particle size: 17.6 ± 6.5 µ, particle number: 1.35 mill./l, particle volume: 5.68 mm3/l, particle surface: 14.91 cm2/l. It is shown, with some assumptions, that the dry weight of detritus particles present in a water sample can be calculated from their size frequency. The obtained results are compared with parallel values derived from chemical analysis of the same samples as follows: seston weight - plankton weight (derived from albumen and chlorophyll content) = detritus weight.

Description: In der Elbmündung erfolgten bei Cuxhaven während einer Tide stündliche Bestimmungen von Gesamtkeimzahlen auf Nährböden mit unterschiedlichem Salzgehalt, sowie der Coliformen- und Hefezahl, und von verschiedenen chemischen und physikalischen Daten. Außerdem wurden in zweistündigem Abstand Vertikalfänge van Phyto- und Zooplankton ausgeführt. Die Untersuchungen erfolgten am 17.VIII.1964, 26.I.1965 und 24.VI.1965 - also zweimal im Sommer und einmal im Winter. Es zeigte sich, daß die Zusammensetzung der Mikroflora- und -fauna während der Tide vor allem in Abhängigkeit vom Salzgehalt beträchtlichen Schwankungen unterliegt. Sehr erheblich ist auch der Einfluß der Cuxhavener Abwässer, der sich besonders 2 1/2 bis 5 Stunden nach Thw auswirkt. Der Abwassereinfluß ist aber in Abhängigkeit vom jeweiligen Oberwasserabfluß und von den meteorologischen Bedingungen nicht immer gleich, sondern kann recht verschieden sein. Die Vertikalverteilung von Seston und Bakterien weist die größten Unterschiede bei nachlassender Strömungsgeschwindigkeit, vor allem bei Tnw auf, da es dann durch Sedimentation zu einer Anreicherung derselben im Tiefwasser kommt. Die Menge der verschiedenen Mikroorganismen läßt große jahreszeitliche Unterschiede erkennen. So nimmt die Gesamtzahl der Bakterien im Winter deutlich zu und die der Phyto- und Zooplankter sehr stark ab. Auch die artenmäßige Zusammensetzung ist sehr verschieden. Bacterial counts on media with different salt concentrations, counts of coliforms and yeast cells as well as the estimation of some chemical and physical dates were carried out every hour and vertical net hauls of phyto and zooplancton every two hours during a tide in the Elbe estuary near Cuxhaven, twice in summer (17.VIII.1964 and 24. VI.1965) and once in winter (26.I.1965). Considerable changes in the composition of microflora and microfauna could be observed during the tide, mainly in dependence on the varying salinity. However there was an important influence of sewage contamination, too, especially 2 1/2 - 5 hours after high tide, being quite different according to the freshwater flow and the meteorological conditions. The vertical distribution of seston and bacteria showed the largest differences with decreasing tidal stream. As a result of sedimentation, seston concentrations and bacterial counts were increasing then in the deep water. Large seasonal changes of the bacterial and plancton counts could be observed. The bacterial counts were significantly increasing in winter while the numbers of phyto and zooplancters were decreasing. The species composition was seasonally changing, too.

Description: Anhand von zwei käuflichen Präparaten wird die Extinktion von Chlorophyll a in verschiedenen Lösungsmitteln untersucht und daraus der Extinktionskoeffizient für frisch extrahiertes, ungetrocknetes Chlorophyll a in Methanol abgeleitet. Er beträgt für das rote Extinktionsmaximum bei 665 nm 75.0 l/g cm. Die Extinktionskoeffizienten von getrocknetem Chlorophyll a sind in den untersuchten Lösungsmitteln 10-25% niedriger als die von einer frisch extrahierten Chlorophyllösung (Tabelle 2). Die Messung des Chlorophyll a-Gehaltes kann mit hinreichender Genauigkeit in einem Filterphotometer (ELKO II, Zeiss) ausgeführt werden. Hierzu werden Eichkurven für drei verschiedene Interferenzfilter angegeben. From two purchasable preparations of crystalline chlorophyll a, the extinction coefficient of undried chlorophyll a in methanol has been calculated as 75.0 l/g cm at the maximum of extinction at 665 nm. The extinction coefficients of dried chlorophyll a in the different solvents tested are 10-25% lower than those of undried chlorophyll a (table 2). Chlorophyll a can be measured in a filter photometer (ELKO II, Zeiss) with sufficient precision. Standard curves for three different interference filters are given.

Description: Nach einer modifizierten Methode von Greenhalgh et. al. (1966) werden Kalium, Natrium und Magnesium durch Trennung mittels eines lonenaustauschers bestimmt. Die Veränderungen der Methode enthalten die Anwendung kleinerer Mengen Elutionslösung, leichtere Trennung und Titration des Kalziums mit EDTA. Es werden Veränderungen in der chemischen Zusammensetzung des Meerwassers aus dem Suez Kanal beobachtet. Die Auswirkungen der Verdünnung durch das Nilwasser bestehen aus einem geringfügig erhöhten Ca++/Cl--Verhältnis im Mittelmeer auf der Höhe von Port Said und im Lake Timsah. Das Salzbett ist sehr arm an Magnesium und Kalium, Kalzium ist geringfügig vermindert, jedoch ist das Na+ /Cl--Verhältnis gegenüber Meerwasser erhöht. Das salzreiche Wasser aus den Bitterseen zeigten kleinere K+/Cl-- und Mg++/Cl--Verhältnisse als normal. Die Beziehungen zwischen dem Chloridgehalt und den Kationen (berechnet nach der Methode der kleinsten Fehlerquadrate) sind nicht konstant, sondern nehmen mit steigendem Chloridgehalt ab oder zu. In einer Tabelle (10) wird eine Formel für die relative Zusammensetzung von Meerwasser aus den Bitterseen angegeben, die ein höheres Na+/CI--Verhältnis anzeigt als normal. Potassium, sodium, calcium and magnesium were determined after separation on an ion-exchanger according to a modified method of Greenhalgh et al (1966). The modifications include smaller amounts of eluting agents, easier separation and titration of calcium with EDTA. Variations in the chemical composition of sea water from the Suez Canal were detected. The effect of dilution by the Nile water is evident in the slightly higher chlorinity ratios of calcium in the Mediterranean off Port-Said and in Lake Timsah. The salt bed was found to be very poor in magnesium and potassium, calcium is slightly reduced, while sodium has higher chlorinity ratio than in sea water. The highly saline waters of the Bitter Lakes show lower values of chlorinity ratios for potassium and magnesium, higher values for sodium, while calcium is slightly reduced. Relationships between the chlorinity and the cations calculated by the least square method show that the chlorinity ratios of the cations are not constant but decrease or increase with increasing chlorinity. A suggested formula for the relative composition of sea water from the Bitter Lakes is given in Table (10) which indicates a higher sodium/chlorinity ratio than normal, and supperts the experimental findings.

Description: Es wurden Nahrungsuntersuchungen, Längen und Nahrungsgewichtsbestimmungen an jungen Schollen, Flundern, Steinbutt und Glattbutt im Sommer ihres ersten Lebensjahres durchgeführt. Das Material wurde in der Nordsee (Nordfriesisches Wattenmeer), Öresund, Samsö Belt, Kieler Außenförde und in der Ostsee bei Bornholm gesammelt. Als Fanggerate dienten die Garnelenkurre, Johansen-Jungfischnetz und Schiebehamen. Auf Grund der Häufigkeit der Nährtiere im Magen wurde Hauptnahrung und Nebennahrung unterschieden. Die Hauptnahrung der Scholle in der Nordsee besteht aus einem Gemisch von Polychaeten und Molluskensiphonen, in der Ostsee aus Polychaeten und Oligochaeten, die Nebennahrung ist in den beiden Gebieten aus Ostracoden, Harpacticiden, Amphipoden und Decapoden zusammengesetzt. Für die Flundern wurden für alle Fanggebiete Oligochaeten und Polychaeten als Hauptnahrung gefunden. Die Nebennahrung besteht aus Ostracoden, Harpacticiden, Amphipoden, Isopoden und Mysidaceen. Für Steinbutt der ersten Bodenstadien bilden bereits Fische und Amphipoden die Hauptnahrung. Mysidaceen und Isopoden können zur Nebennahrung gezählt werden. Die Nahrung des jungen Glattbutt setzt sich aus drei Komponenten von etwa gleicher Bedeutung zusammen: Mysiclaceen, Crangon und Fische. Zur Klärung der Tagesperiodik der Nahrungsaufnahme wurde die Häufigkeit gefüllter und leerer Mägen zu verschiedenen Tageszeiten bestimmt. Dabei wurde auch der Füllungsgrad berücksichtigt, der sich aus dem prozentualen Gewichtsanteil des Mageninhalts am Gesamtkörpergewicht ergibt. Aus den tagesperiodischen Schwankungen in den Fangerträgen des Schiebehamen konnte auf eine kräftige nächtliche Schwimmaktivität der jungen Flundern geschlossen werden. Im Nordfriesischen Wattenmeer betrug das Längenwachstum der Schollen während ihres ersten Sommers 0,6 mm pro Tag. The feeding habits, amount of food and growth rate of juvenile plaice, flounder, turbot und brill were investigated during the first summer. The fishes were caught in the North Sea (North Frisian Shallows), Öresund, Samsö Belt, the outer region of the Kiel Fjord and in the Baltic near the island of Bornholm. As fishing gear we used a beam trawl, a Johansen-trawl for small fishes, and a push net. The plaice of the North Sea feeds mainly on polychaetes and the siphons of molluscs. In the Baltic Sea the diet of this fish consists mainly of polychaetes and oligochaetes, and in both areas ostracods, harpaticoids, amphipods and decapods are found as secondary food animals. In all areas the main food of the flounder are oligochaetes and polychaetes. Ostracods, harpacticoids, amphipods, isopods, and mysids are of lesser importance. The turbot feeds already as juvenile fish mainly on fish and amphipods. In this fish mysids and isopods are secondary food animals. The brill feeds to equal extent on mysids, Crangon and fish. A diurnal rhythm of feeding was found by recording the frequency of full and empty stomachs at different limes of the day. The proportion of the weight of the stomach contents to the total body weight was also recorded. From the diurnal variations in the yield of the push nets, it is obvious that in young flounders swimming activity is high during night. In the North Frisian Shallows the average growth is bodylength of the plaice is 0,6 mm per day during its first summer.