ALBERT

Description: Oithona similis is an abundant but poorly studied cyclopoid copepod in the brackish Central Baltic Sea. We describe the spatio-temporal distribution of O. similis in a Central Baltic deep basin (Bornholm Basin) during spring and summer 1999. Using vertically resolving sampling in parallel with hydrographic measurements, we found the copepod to dwell in the permanent halocline characteristic of a Central Baltic deep basin. The habitat of O. similis is thus limited from above by low salinity and from below by low oxygen conditions, both characteristic for the area. Horizontally resolving sampling yielded abundance surfaces which were compared by analysis of variance showing similar patterns among sampling dates. Comparison with flow fields from a three-dimensional hydrodynamic model suggests that the horizontal distribution is primarily the result of circulation in the dwelling depth. The study shows how the physical environment in the area determines the spatial distribution which might affect abundance and production of this copepod.

Description: The seasonal development of bacteria was studied in the hypertrophic coastal lagoon Ciénaga Grande de Santa Marta (Caribbean coast of Colombia). This large but only 1.5 m deep lagoon is subject to strong seasonal variations of salinity from almost fully marine (April/May) to brackish conditions in October/November. Chlorophyll ranged from 6 to 182 μg L−1, and gross primary production amounted to 1690 g C m−2 per year. Total bacterial number (TBN) ranged from 6.5 to 90.5 × 109 cells L−1 and bacterial biomass (BBM) from 77 to 1542 μg C L−1, which are among the highest ever reported for natural coastal waters. Neither TBN nor BBM varied significantly with salinity, phytoplankton or seston concentrations. Only the bacterial mean cell volume showed a significant relation to salinity, being highest (0.066 μm3) during the period of increasing and lowest (0.032 μm3) during decreasing salinity. Bacterial protein accounted for 24% (19–26%) and phytoplankton protein for 57% (53–71%) of total seston protein. The ratio (annual mean) of bacterial carbon to phytoplankton carbon was 0.44 (range 0.04–1.43). At low phytoplankton abundance [chlorophyll a (Chl a) 〈 25 μg L−1], bacterial carbon was almost equal to phytoplankton biomass (i.e. the mean ratio was 1.04). In contrast, at Chl a 〉 100 μg L−1, BBM was low compared to phytoplankton biomass (the mean ratio was 0.16). In general, BBM varied less than phytoplankton biomass. Most probably, the missing correlation between bacterial and phytoplankton variables was due to (i) organic material partly derived from allochthonous sources serving as food resource for bacteria and (ii) a strong resuspension of bacteria from the sediment caused by frequent wind-induced mixing of the very shallow lagoon.

Description: The so-called ‘turbulence incubator’ overcomes an essential disadvantage of static in situ incubations where at high irradiances an artificial photoinhibition is caused by neglecting turbulent mixing in the upper water column. It is operated on deck and simulates the changing light conditions for vertically mixed phytoplankton cells by moving the sample bottles horizontally through a circular water bath covered by a glass lid of neutral optical density filters. In this way the exponentially decreasing irradiance within the euphotic zone is simulated and photoinhibition near the surface is avoided. A crucial point is the choice of revolution rate for simulating turbulent mixing under natural conditions. The incubator is characterized by its handy size, a relatively simple and inexpensive construction and a battery-driven motor. It can thus even be operated on small vessels without an electric generator. The incubator is especially suited for vertically mixed waters such as shallow bays, tidal estuaries and rivers. Its reliability was successfully tested by a simultaneous comparison with in situ measurements at various stations representing different water types and environmental conditions, ranging from the turbid River Elbe to the clear open Baltic Sea. In 9 out of 11 experiments, higher primary production rates were obtained in the turbulence incubator than in static in situ incubations. The majority of the latter were characterized by a pronounced photoinhibition in the upper two incubation depths representing the 100 and 50% light levels. The average rate increase amounted to 22%, with a range between 11 and 53% depending on light attenuation and irradiance.

Description: The vertical distribution patterns of paralarvae from several abundant cephalopod taxa were examined from depth-stratified tows in the northeast Pacific (44–56°N, 145–165°W) during three summer surveys in 1999–2001. A total of 309 cephalopods representing 10 taxa in three families were collected. Gonatid squids composed 97% of the total catch, and the most numerous taxa were Berryteuthis anonychus (59% of the total catch), Gonatus spp. (21%) and Gonatopsis borealis (17%). B. anonychus and Gonatus spp. were both most abundant in the upper 20 m; catches of both taxa varied significantly with depth and were significantly higher above the thermocline than in and below the thermocline. Gonatopsis borealis was collected mostly between 20 and 50 m, and catches were significantly higher in the thermocline than above and below the thermocline. Paralarvae of the three major taxa showed no evidence of diel vertical migration. Mantle lengths of Gonatus spp. and G. borealis each varied significantly with depth, and Gonatus spp. showed a strong positive correlation between mantle length and depth.

Description: Selectivity-size spectra, clearance and ingestion rates and assimilation efficiencies of Acartia clausi (Copepoda), Penilia avirostris (Cladocera) and Doliolum denticulatum (Doliolida) from Blanes Bay (Catalan Sea, NW Mediterranean) were evaluated in grazing experiments over a wide range of food concentrations (0.02–8.8 mm3 L−1 plankton assemblages from Blanes Bay, grown in mesocosms at different nutrient levels). Acartia clausi reached the highest grazing coefficients for large algae 〉70 μm (longest linear extension), P. avirostris for intermediate food sizes between 15 and 70 μm, and D. denticulatum for small sizes from 2.5 to 15 μm. Penilia avirostris and D. denticulatum acted as passive filter-feeders. Acartia clausi gave some evidence for a supplementary raptorial feeding mode. Effective food concentration (EFC) decreased linearly with increasing nutrient enrichment for D. denticulatum and followed domed curves for A. clausi and for P. avirostris with maximum values at intermediate and high enrichment levels, respectively. Clearance rates of crustacean species showed curvilinear responses with narrow modal ranges to increasing food concentration. Clearance rates of D. denticulatum increased abruptly and levelled into a plateau at low food concentrations. Mean clearance rates were 13.9, 25.5 and 64.1 mL ind.−1 day−1, respectively. No clearance could be detected for A. clausi at food concentrations 〈0.1 mm3 L−1 and for P. avirostris at food concentrations ≤0.02 mm3 L−1. Ingestion rates indicate a rectilinear functional response for A. clausi and for P. avirostris and showed a sigmoidal curve for D. denticulatum. Mean ingestion rates were 1.3, 2.8 and 7.7 μg C μg Cind.−1 day−1, respectively. Conversion of ingested carbon to tissue was 30–80% for the investigated crustaceans and 20–50% for doliolids. Food niche calculations suggest that food niche separation may explain the coexistence of the three species in summer in Blanes Bay.

Description: The δ15N of marine mesozooplankton species was measured on four occasions. Significant differences were found between copepods and meroplanktonic larvae, yet not between holoplanktonic species. On average, mesozooplankton was enriched by 3.4 ± 0.9‰ relative to selected seston size fractions. Despite suggesting small differences (∼0.5 to 1‰) in the δ15N of different phytoplankton taxa on one occasion, the size fractionation procedure generally proved inadequate in separating major taxonomic groups composing seston. This circumstance, and phase-shifts in the transmission of rapid changes (〉2‰) in seston δ15N to mesozooplankton complicate the calculation of mesozooplankton trophic levels.

Description: Im Nordpolarmeer gehört die Aufsammlung benthischer Organismen zu den ältesten wissenschaftlichen Aktivitäten. Die in erster Linie taxonomischen und zoogeographischen Fragestellungen beschränkten sich allerdings auf die flachen, im Sommer Eis freien Sehelfbereiche.

Description: In a mesocosm study, the appendicularian Oikopleura dioica bloomed after the reduction of copepod abundance, and in a second treatment showed a significantly negative correlation with copepod densities. Calculations, together with field data from the Baltic Sea, suggest that common calanoid copepods may control appendicularian population dynamics.

Description: The development and application of a dilution method for measuring primary production in coastal waters is described.

Description: We used otolith microstructure analysis to reconstruct the growth histories of larval radiated shanny ( Ulvaria subbifurcata ) collected over a 2-week period in Trinity Bay, Newfoundland. A dynamic 3-dimensional, eddy-resolving circulation model of the region provided larval drift patterns, which were combined with measurements of temperature and zooplankton abundance to assess the environmental history of the larvae. The abundance of juvenile and adult capelin ( Mallotus villosus ), the dominant planktivorous fish in this area, was monitored using five hydroacoustic surveys. The goal was to determine whether environmental histories are helpful in explaining spatial and temporal differences in larval shanny growth, measured as cumulative distribution functions (CDF) of growth rates. We found evidence for a selective loss of slower growing individuals and recognized considerable spatial differences in the CDF of larval growth rates. Consistent patterns in capelin abundance suggested that faster growing survivors, sampled at the end of the 2-week period, developed in areas of low predator densities. A dome-shaped relationship between temperature and larval growth was observed, explaining a significant but small amount of the overall variability (14%). Effects of experienced prey concentrations on larval growth rates could not be demonstrated.

Description: Im Bereich der westlichen Grönlandsee wurde bisher nur die gesamte Megafauna hinsichtlich ihrer Abundanzen und Besiedlungsmustem in der Literatur beschrieben und nicht zwischen einzelnen Substraten unterschieden. Dies geschah ausschließlich auf dem ebenen Meeresboden und nicht innerhalb von geologischen Strukturen, wie z.B. Rinnensystemen. In der vorliegenden Arbeit wurden Abundanzen und Verteilungsmuster für die Hartsubstratfauna und die eng mit dem Hartsubstrat assoziierte Fauna in der Rinne vor Grönland beschrieben.

Description: Miocene Ignimbrite ‘A’ on Gran Canaria contains three compositional endmember fiamme types(two rhyolites and one trachyte) each of which crystallized distinct feldspar. Various textural and compositional criteria are interpreted as reflecting a complex scenario within the magma chamber in which the crystals formed. About 25–30% of the feldspar phenocrysts contain evidence for magma mixing in the form of (1) partial to severe dissolution–resorption rims, (2) distinct zones of drastically different compositions and (3) overgrowth textures on formerly resorbed crystals. Four major types of zoning in the oligoclase to anorthoclase feldspars of ignimbrite ‘A’ include a normal and a reversely zoned type and two complexly zoned types. The feldspars with normal and reverse zonation show only minor compositional amplitudes between individual zones (ΔAb, Or ∼4%), whereas the complexly zoned types show compositional differences between zones of up to 18 mol % Ab and 20 mol % Or and are commonly associated with an internal dissolution surface. Complex zoning with large compositional amplitudes and dissolution textures is taken as evidence of crystal movements within the magma and across compositional boundaries between magma batches. A multiple ‘step-cycle’ model, involving growth and transport of a crystal into another magma batch and its return to the original host magma, is suggested by the data. Moreover, feldspars from one rhyolite compositional group are found to be substantially elevated in δ18O, suggesting an input of a high δ18O component to this rhyolite. The other endmember rhyolite appears to be related to the endmember trachyte by mainly crystal fractionation of anorthoclase feldspar. This observation is consistent with trace element and rare earth element concentrations for the magma endmembers and their feldspars, where contamination led to a depletion in incompatible trace elements and light rare earth elements in the contaminated rhyolite and its feldspar phenocrysts. We suggest that the combination of textural and compositional variation in ternary feldspar of peralkaline rhyolitic systems is well suited to reconstruct dynamic processes such as magma mixing and contamination in evolving rhyolitic magma chambers.

Description: Incubation experiments with natural phytoplankton revealed a relationship between CO2 concentration and the production of transparent exopolymer particles (TEP), with TEP production being linearly related to theoretical CO2 uptake rates.

Description: Population dynamics of major Baltic calanoid copepod species in the Gotland Basin during the last two decades were characterized by a decline of Pseudocalanus elongatus associated with declining salinities, and an increase of Temora longicornis and Acartia spp. potentially due to warmer conditions. Additionally this study investigated the effect of predation by the major planktivorous fish species herring (Clupea harengus) and sprat (Sprattus sprattus) for the period 1977–1996 in the Gotland Basin (Central Baltic Sea). Examination of consumption by these fish species in relation to copepod production estimates showed a switch by herring from consuming mainly CV/VI of P. elongatus and T. longicornis, to preying on CII of the latter copepod. This switch was potentially due to increased competition with the drastically increased sprat stock since the late 1980s. Further, an increased predation pressure by sprat on CV/CVI of both copepod species in spring resulted in higher copepod mortality rates. In consequence, based on these results we suggest that the increase in the sprat stock since the late 1980s contributed to a decline of P. elongatus, and additionally prevented an even more pronounced temperature-driven increase in the T. longicornis stock, as was observed for Acartia spp., which was not significantly consumed.

Description: Das Laptevmeer stand in den letzten Jahren im Mittelpunkt vieler interdisziplinärer Studien. Seine Hydrographie wird wesentlich charakterisiert durch den saisonalen Einstrom gewaltiger Wassennassen aus den sibirischen Flüssen, besonders der Lena, welcher nicht nur Süßwasser, sondern auch große Mengen Seston und Nährstoffe ins Laptevrneer einträgt (z.B. Timokhov 1994, Alabyan et al. 1995, Pivovarov et al. 1999). Ein weiteres Merkmal ist die lang andauernde Eisbedeckung, mit nur wenigen eisfreien Sommermonaten. So wird eine extrem variable Umwelt für die Planktonorganismen des Laptevmeeres bezogen auf Wassertemperatur und Salinität, Wassertrübung und Nährstoffe(Lischka et al. 200 l) geschaffen.

Description: To test the effects of diatom production on larval fish growth and condition, laboratory experiments were performed with larval North Sea cod reared on different algal food chains. These food chains were based on cultures of (a) the diatoms Skeletonema costatum and Thalassiosira weissflogii; (b) the dinoflagellate Heterocapsa triquetra; (c) the flagellate Rhodomonas baltica; (d) a diet composed of both Skeletonema and Heterocapsa food chains (1:1), and (e) a starvation group. These algae were fed to cultures of adult Acartia tonsa. Copepod eggs were collected, hatched, and the N1 nauplii (200l−1) were fed to post-yolk-sac larval cod. Results indicate that larval growth rates are significantly influenced by the content of essential fatty acids of the algal food source: growth rates were positively correlated with the content of DHA (C22:6ω3) and negatively with EPA (C20:5ω3). The ratio of ω3/ω6 fatty acids in the algal source had no significant effect. The highest and lowest growth rates were observed in food chains based on H. triquetra and T. weissflogii, respectively (means for days 14–16 of 4.0 and −4.7). The mixed diatom/dinoflagellate diet resulted in intermediate growth rates and condition. Regressions of growth rates against EPA and DHA content indicated no inhibitory effect of diatom production on growth in larval cod.

Description: Retention or dispersion of larvae from the spawning grounds has been identified as one of the key processes influencing recruitment success in fish stocks. To examine the potential effects of transport on recruitment, numerical simulations were performed utilizing a three-dimensional physical oceanographic model of the Baltic Sea. Cod larvae were represented as Lagrangian drifters released in the deepwater region of the Bornholm Basin, the main spawning ground for Baltic cod. Simulations were performed for the major spawning seasons of 1993 and 1994, when annual and interannual variability of meteorological forcing was large. The principal goals of the modelling exercise were first to identify the physical processes influencing the demersal distribution of the early life stages and second to describe the transport of the pelagic stages in response to variations in windstress, thereby identifying the meteorological and hydrodynamic mechanisms influencing retention and/or dispersal. The results suggest that periods of low wind, especially from northern and eastern directions, retain early life stages of cod within the deepwater region of the Bornholm Basin. Periods of higher windstress and duration from the west and south resulted in a rapid transport of larvae into shallow coastal regions. Based on the results obtained from these drift experiments and a wind data time series from the meteorological station Christiansoe, a transport index has been developed, variations in annual retention/ dispersal have been identified, and comparisons with variations in recruitment success are presented.

Description: Diatoms exude considerable quantities of polymers, mainly polysaccharides, that play an important role in the process of sestonic particle aggregation in the sea. We investigated the impact of copepods on transparent exopolymeric particles (TEP) generated by the diatom Thalassiosira weissflogii. Grazing experiments with 14C-labelled algae exudates demonstrated that copepods typical of the Baltic Sea were not actively filtering TEP. Control experiments showed that ‘uptake’ of radioactivity could be ascribed to passive uptake, such as adsorption of radioactively-labelled particles to the body surface. Furthermore, we tested the effect of copepods on TEP size spectra. The abundance and size distribution of TEP (from 1.4 to 180 μm of Equivalent Spherical Diameter) were analysed in a 4 h incubation experiment. In the presence of copepods, the proportion of larger TEP was higher. An increase in total volume of TEP in jars containing copepods (~2 × 107 μm ml–1) compared with control jars without copepods (~0.5 × 107 μm3 ml–1) was also observed. The process of aggregation of TEP demonstrated in this work, whereby copepods increase downward particle flux without consuming carbon, can have far-reaching consequences for carbon fluxes along the water column and for copepods feeding dynamics.

Description: Long-term dynamics (1959–1997) of the copepod species Pseudocalanus elongatus, Temora longicornis, Acartia spp. and Centropages hamatus, as well as the taxonomic group of cladocerans, are described for the open sea areas of the central Baltic Sea. Differences between areas, i.e. Bornholm Basin, Gdansk Deep and Gotland Basin, as well as between 5 year periods, were investigated by means of Analysis of Variance (ANOVA). No significant differences in mesozooplankton biomass between areas were found. On the other hand, clear time-trends could be demonstrated and related to salinity and temperature, with P.elongatus biomass mainly dependent on salinity and T.longicornis, Acartia spp. and cladocerans biomasses dependent, to a large extent, on thermal conditions. Decreasing salinities since the early 1980s due to a lack of major inflows of highly saline water from the North Sea and increased river run-off, both triggered by meteorological conditions, obviously caused a decrease in biomass of P.elongatus. Contrarily, the standing stocks of the other abundant copepod species and cladocerans followed, to a large degree, the temperature development and showed, in general, an increase. The shift in species composition during this period is considered to be a reason for decreasing growth rates of Baltic herring (Clupea harengus) since the early 1980s, and for sprat (Sprattus sprattus) since the early 1990s. Generally, it is suggested that low mesozooplankton biomasses in the 1990s were caused, at least partially, by amplified predation by clupeid fish stocks.

Description: Qualitative historical benthos data (1902–1912) were compared with recent data (1986) to find long-term trends in epifauna species composition in the southern North Sea that may be attributed to fishery-induced changes. In general, the frequency of occurrence of bivalve species declined, whereas scavenger and predator species (crustaceans, gastropods, and sea stars) were observed more frequently in 1986. We suggest that these shifts can be attributed not only to the physical fishery impact, but also to the additional potential food for scavenging and predator species provided by the large amounts of discards and moribund benthos. Our findings are put into the perspective of the general development of the demersal fishery in the southern North Sea. Despite the problems with the historical data set, the comparison presented may be the best illustration achievable of the changes in the benthos from a near-pristine situation to the present conditions after long-term disturbance.

Description: Throughout the 1980s, reproductive success of the top-predator cod declined and stock sizes of the main prey species herring and especially sprat, important planktivorous predators in the system, increased substantially. Although the hydrographic conditions conducive for survival of early life stages improved during the 1990s, recruitment success of cod remained far below average. As clupeids have been identified as major predators on cod eggs and larvae in the Baltic, increased predation may be an important factor hampering stock recovery. Results from stomach content analysis of herring and sprat during the spawning season of 1988–1995 and ichthyoplankton surveys in the Bornholm Basin (the only important spawning area of cod in the Central Baltic in this period) allow a comparison of estimated consumption rates by the predator populations with standing stocks and production rates of cod eggs and larvae. Despite uncertainties in the estimation procedure, the findings confirm substantial predation on cod eggs by both clupeid species. Especially at the beginning of the cod-spawning season, characterized by low zooplankton availability, sprat consumed a considerable proportion of the eggs produced. In 1993, the relative importance of zooplankton as prey increased, while fish eggs were encountered more rarely. In contrast, predation by herring remained on the same level or even increased, especially late in the spawning season. The larval stage of cod is not substantially affected by predation owing to limited spatial overlap between prey and predator.

Description: Birds are the most conspicuous, wide-ranging, and easily studied organisms in the marine environment. They can be both predators and scavengers, and they can be harmed by and can benefit from fishing activities. The effects of fishing on birds may be direct or indirect. Most direct effects involve killing by fishing gear, although on a lesser scale some fishing activities also disturb birds. Net fisheries and hook fisheries have both had serious negative effects at the population level. Currently, a major negative impact comes from the by-catch of albatrosses and petrels in long-lines in the North Pacific and in the Southern Ocean. High seas drift nets have had, prior to the banning of their use, a considerable impact on seabirds in the northern Pacific, as have gillnets in south-west Greenland, eastern Canada, and elsewhere. Indirect effects mostly work through the alteration in food supplies. Many activities increase the food supply by providing large quantities of discarded fish and wastes, particularly those from large, demersal species that are inaccessible to seabirds, from fishing vessels to scavengers. Also, fishing has changed the structure of marine communities. Fishing activities have led to depletion of some fish species fed upon by seabirds, but may also lead to an increase in small fish prey by reducing numbers of larger fish that may compete with birds. Both direct and indirect effects are likely to have operated at the global population level on some species. Proving the scale of fisheries effects can be difficult because of confounding and interacting combinations with other anthropogenic effects (pollution, hunting, disturbance) and oceanographic factors. Effects of aquaculture have not been included in the review

Description: Annual catches of Todarodes pacificus in Japan have gradually increased since the late 1980s. Paralarval abundances have also been higher since the late 1980s compared to the late 1970s and mid-1980s. Here is proposed a possible scenario for the recent stock increase based on changing environmental conditions. Based on trends in annual variations in stock and in larval abundances, catches are reviewed and potential spawning areas inferred, assuming that egg masses and hatchlings occur over the continental shelf at temperatures between 15 and 23°C. Changes are then inferred in the spawning areas during 1984–1995, based on GIS data. Since the late 1980s, the autumn and winter spawning areas in the Tsushima Strait and near the Goto Islands appear to have overlapped, and winter spawning sites seem to have expanded over the continental shelf and slope in the East China Sea.

Description: Aspartate transcarbamylase (ATCase) activity was used to estimate instantaneous growth in young cuttlefish (Sepia officinalis) reared under different diet conditions, and compared with estimation obtained by RNA concentration. During the first month of life, the changes in ATCase activity and RNA content of muscle are related to growth. ATCase appears to be a good index of growth during the first stage of intense cell multiplication. ATCase activity is correlated to food intake up to a maximum ration, but decreases when animals are more than 40 days old. The approach of using ATCase activity as a biochemical index for estimating short-term change in growth rates of young cuttlefish in experimental rearing could be extended to young cephalopods collected in the field, and used to predict the effect of biotic factors in recruitment.

Description: A new species of eledonid octopus is described from the southwestern Atlantic Ocean from depths between 90 and 1000 m off the coasts of southern Brazil, Uruguay, and Argentina. This species, Graneledone yamana is characterized by having a papillose skin, two well developed 'horns' above the eyes, small gills with 5-7 lamellae on the outer demibranch, arms with uniserial suckers, 35-80 on females and 26-70 on males. The third right arm is hectocotylized, the ligula is small, the calamus is large and well differentiated. Ink sac absent. These characters differ from all other known Graneledone species from the southern oceans.

Description: Phylogenetic analysis conducted on a 784-bp fragment of 82 actin gene sequences of 44 coleoid cephalopod taxa, along with results obtained from genomic Southern blot analysis, confirmed the presence of at least three distinct actin loci in coleoids. Actin isoforms were characteri zed through phylogenetic analysis of representative cephalopod sequences from each of the three isoforms, along with translated actin cDNA sequences from a diverse array of metazoan taxa downloaded from GenBank. One of the three isoforms found in cephalopods was closely related to actin sequences expressed in the muscular tissues of other molluscs. A second isoform was most similar to cytoplasmic-specific actin amino acid sequences. The muscle type actins of molluscs were found to be distinct from those of arthropods, suggesting at least two independent derivations of muscle actins in the protostome lineage, although statistical support for this conclusion was lacking. Parsimony and maximum-likelihood analyses of two of the isoforms from which 〉30 orthologous coleoid sequences had been obtained (one of the cytoplasmic actins and the muscle actin) supported the monophyly of several higher-level coleoid taxa. These included the superorders Octopodiformes and Decapodiformes, the order Octopoda, the octopod suborder Incirrata, and the teuthoid suborder Myopsida. The monophyly of several taxonomic groups within the Decapodiformes was not supported, including the orders Teuthoidea and Sepioidea and the teuthoid suborder Oegopsida. Parametric bootstrap analysis conducted on the simulated cytoplasmic actin data set provided statistical support to reject the monophyly of the Sepioidea. Although parametric bootstrap analysis of the muscle actin isoform did not reject sepioid monophyly at the 5% level, the results (rejection at P = 0.068) were certainly suggestive of sepioid nonmonophyly.

Description: Cod is the top piscivore predator in the Baltic Sea ecosystem. Based on stomach content data from 62 427 cod collected during 1977–1994 and food consumption rates, cannibalism in the Eastern and Western Baltic cod stocks has been quantified using multispecies virtual population analysis. In the Eastern Baltic stock, depending on model assumptions, an average of 25–38% of the 0-group and 11–17% of the 1-group were removed by predation by adults. Thus, between age 0 and age 2 a year class may lose on average about 31% and 44% of the initial number as a result of cannibalism. Cannibalism is lower in the Western Baltic. On average, 19% of the 0-group and 9% of the 1-group are consumed per year, i.e. 24% of the initial cohort is eaten before reaching age 2. Predation was most intense in 1978–1984, a period with high juvenile abundance and large adult stock sizes in both areas. Subsequently, stock, recruitment, and cannibalism declined steadily until the early 1990s and then increased again. Problems identified in relation to data compilation and estimation procedure are discussed with respect to their impact on estimates of cannibalism and stock– recruitment relationships

Description: In an assessment of non-indigenous species transported by international ship traffic to German waters, commissioned by the German Federal Environmental Agency, the survival of tropical plankton organisms in ballast water was studied by accompanying a container vessel on its 23-day voyage from Singapore to Bremerhaven in Germany. Two tanks, one filled off Singapore and the other off Colombo, Sri Lanka, were monitored for their phyto- and zooplankton content by daily sampling. As already reported in previous studies, species abundance and diversity, especially of zooplankton, decreased sharply during the first days, and only a few specimens survived the whole cruise. The contents of the Colombo tank, however, changed dramatically during the last week. The harpacticoid copepod, Tisbe graciloides, increased its abundance by a factor of 100 from 0.1 to 10ind. l–1 within a few days. This is the first time that a ballast water organism has been found to multiply at such a high rate. Opportunistic species such as Tisbe are apparently able to thrive and propagate in ballast water tanks under certain conditions. Ballast water tanks may thus serve as incubators for certain species depending on their characteristics.

Description: The termination of diatom spring blooms in temperate waters has been connected with the formation and subsequent rapid sedimentation of aggregates. According to coagulation theory, the rate of aggregate formation depends on the probability of particle collision and on the efficiency with which two particles adhere once they have collided (stickiness). During this study, the variation in particle stickiness was determined over the decline of a diatom bloom using the Couette Chamber assay with low shear (G = 0.86 s–1). A mixed diatom population, dominated by Skeletonema costatum, was sampled during the spring bloom in the Baltic Sea and incubated in the laboratory for 18 days. Measurements of diatom species composition, transparent exopolymer particles (TEP) and bulk particle abundance, as well as chemical and biological variables, were conducted in order to reveal the determinants of coagulation efficiency. The investigation showed that an increase in TEP concentration relative to conventional particles at the decline of the bloom significantly enhanced apparent coagulation efficiencies. High proportions of TEP led to apparent values of stickiness 〉1, which indicates that collision rates can be substantially underestimated when the stickiness parameter α is calculated on the basis of conventional particle counting only, e.g. with the Coulter Counter. A new stickiness parameter, α′, was therefore estimated based on the combined volume fractions of TEP and conventional particles. The problems of stickiness measurements are discussed and the role of TEP in coagulation processes is emphasized.

Description: In der letzten Ausgabe der "Mitteilungen zur Kieler Polarforschung" habe ich über die Gefrierschutzproteine bei Pleuragramma antarcticum berichtet. Dabei habe ich unter anderem ein bislang unbekanntes Glykoprotein vorgestellt, welches nur bei dem antarktischen Silberfisch nachgewiesen werden konnte. Heute möchte ich auf die anderen Arten des Weddellmeeres und Lasarewmeeres eingehen, die ich im Rahmen meiner Promotion auf den Gefrierschutz hin untersucht habe ( WÖHRMANN & ZIMMERMANN 1992; WÖHRMANN 1993).

Description: Die resultierende Kraft aus dem Kräftedreieck Fischerei. Fischereiforschung und Fischereiverwaltung soll die nachhaltige Nutzung mariner und limnischer Fischbestände sichern. Der Informationsfluß von der Forschung (Wissenschaft)über das Management (Politik) zur Administration (einschl. Kontrolle) soll die Fischerei nach wirtschaftlichen und populationsdynamischen Kriterien steuern. Da weltweit zahlreiche Fischbestände zusammengebrochen sind, stellt sich die Frage, warum das System versagt hat. Warum schaffen wir, die wir regeln wollen, keine Ordnung in der Fischerei?

Description: Artificial selection processes associated with harvesting may operate over relatively short time scales in short-lived semelparous species. The ommastrephid squid Illex argentinus on the Patagonian Shelf is the target of a major fishery. Recent work has provided new information on the biological characteristics of squid in this fishery. That information has been utilized in the development of a model of the cohort dynamics and some of the within-seasons selective effects considered. The model results are consistent with earlier data from the shelf fisheries, supporting suggestions that the males nature and migrate earlier towards the spawning grounds than the females. Earlier maturation results in a smaller mean size in the spawning stock, while later maturation results in greater exposure to the fishery and a reduced numbers of individuals surviving to spawn. Under the current fishing regime greater egg production and a larger spermatophoric complex mass for the whole cohort is achieved by relatively late maturation. In general, however, the earlier maturation occurs, the earlier is the peak in total egg production. The within-season pattern of effort expenditure in the fishery can affect not only yield from the fishery but also the reproductive potential of the spawning stock. The management policy adopted for this fishery is likely to be conservative in terms of maintenance of a spawning stock, however, the potential for selective effects is larger and this may affect both yield and reproductive potential. The results are discussed in relation to short- and long-term effects in the fishery and the implications for future research requirements.

Description: Fahrtbericht der GEOMAR-Expeditionsteilnehmer. Fahrtroute (5.8. - 5.10.1993): Tromsoe - Murmansk - Svalbard - Franz-Josef-Land - Karasee - Laptevsee - Karasee - Barentsee - Murmansk - Bremerhaven

Description: Im Frühjahr 1967 hielt ich meine Antrittsvorlesung über die marine Aquakultur - die Fischzucht am und im Meer. Ich wollte damit eine neue Arbeitsrichtung in Kiel einläuten. Sie wurde in den folgenden Jahrzehnten zu einem wichtigen Feld der Fischereibiologie in Kiel. Thassilo Jaegers Lachsforellen, am Kieler Kraftwerk in Holger Graves Drehnetzkäfigen aufgezogen, und die Steinbutt-Küken aus Bülk sind Folgen dieseranschließend von Nellen und Rosenthal fortgeführten Arbeitsrichtung. (...)

Description: Vesteris Seamount is a solitary alkaline volcano in the Greenland Basin some 280 km NW of Jan Mayen. Topographic and geophysical studies have shown no sign of an associated plume trace. Evidence from ash layers in sediment cores around the volcano and dating of dredged samples show that it has been active in Quaternary times. The lavas from Vesteris studied here consist of basanites, tephrites, mugearite, and alkali basalts. Crystal fractionation models are consistent with the generation of the tephrites and mugearite from a basanitic parent. Extensive kaersutite fractionation is required late in the fractionation sequence to produce the extreme mugearite composition. Na-Al-Fe-rich green cores to many clinopyroxene phenocrysts at Vesteris suggest a fractionation history beginning at high pressure in the mantle. Differences between Vesteris and Jan Mayen in the ratios of highly incompatible trace elements such as Ce/Pb and Rb/Cs, which will not normally be fractionated from one another during mantle melting, suggest that the two are not derived from the same source. Relatively unradiogenic Sr isotope ratios (compared with Bulk Earth), and highly incompatible trace element patterns similar to those for St. Helena, suggest that Vesteris magmas are derived from a depleted, asthenospheric source. We propose that the Vesteris basanites are very low degree partial melts (˜1%) of this source, most probably those which give rise to the seismic low-velocity zone (LVZ). Such small-degree melts may preferentially tap small-scale heterogeneities in the asthenosphere. Vesteris lies at the intersection of two major structural trends in the Greenland Basin—(1) a zone of major reorientation of spreading direction on the Mohns Ridge north of Jan Mayen and (2) the extension of the Kolbeinsey Ridge axis. We propose that a combination of the extensional stress fields related to these two lineaments produces sufficient dilation of the lithosphere at Vesteris to allow magmas from the LVZ to reach the surface.

Description: The population dynamics and the trophic role of Aurelia aurita medusae in the Kiel Bight/western Baltic are described from nine years of investigation between 1978 and 1993. There is considerable yearly variation in standing stock with summer median abundance ranging from 0.2 to 16 ind. 100 m−3 and biomass from 0.2 to 4.4 g C 100 m−3. The lower variation is due to marked differences in size of adult medusae between years. In years of low abundance medusae exhibit an average dise diameter of about 30 cm and weight about 1 kg. In bloom years, however, adult size is only about 20 cm and weight ranges between 200 and 400 g. Estimates of feeding are somewhat contradictory, but feeding rates of 40–80 mg C ind.−1 day−1 seem probable. It can be concluded that Aurelia medusae consume about 2/3 of daily secondary production in years of high abundance, and are thus responsible for a decline of mesozooplankton in these years.

Description: An investigation was carried out on larvae of the oceanic tropical squid Sthenoteuthis pteropus in the equatorial Atlantic (2°30′N–7°S;12°W –8°30′E) The age of the larvae was calculated from the statolith microstructure of 20 larvae; mortality was estimated from the size structure of 1128 larvae. The larval stage lasts 32–38 days. At ages ranging from 14 to 38 days. the daily relative growth rates of mantle length decrease from 7.5 to 2.8% day −1 and from 14–16 to 5.8% of body weight day −1 At age 12–24 days, mortality rates were estimated using both raw catch data and corrected data accounting for net avoidance. The mean value of raw mortality rates was 0.189, the corrected value was 0.158. During the proboscis division (transformation of the larva into juvenile) at age 25–35 days, a sharp decrease in larval growth rates and a simultaneous increase in mortality rates (raw 0.443, corrected 0.379) were observed.

Description: Die Terra Nova Expedition (1910-1913) von Robert Falcon Scott wird bis heute überschattet von dem tragischen Ende des Vorstoßes zum Südpol, den Scott mit seinen vier Begleitern im Januar 1912 - einen Monat nach Amundsen - erreichte. Dabei gerat leicht in den Hintergrund, daß neben dem Vorstoß zum Pol umfangreiche wissenschaftliche Untersuchungen einen wichtigen Schwerpunkt der Expedition bildeten. So wurden zahlreiche meteorologische, geologische und biologische Untersuchungen und Erkundungen von mehreren, unabhängig voneinander operierenden, wissenschaftlichen Feldgruppen durchgeführt. Eine dieser Feldgruppen war die Western Geological Party', die im Sommer 1911/12 unter der Leitung des Geologen Griffith Taylor von Granite Harbour ausgebend, einem tiefen natürlichen Hafen auf 77°S, die Küste von Süd Victoria Land erkundete. Die Forschungsergebnisse mit Hinweisen auf eine außergewöhnlich reiche Vegetation wurden im Reisebericht der Terra Nova Expedition bereits 1913 veröffentlicht (TAYLOR 1913). Aufgrund seiner abgeschiedenen Lage ist dieses Gebiet seitdem jedoch nur sehr selten besucht worden und in Vergessenheit geraten, ast 1989 wurde die außergewöhnlich reiche Vegetation wiederentdeckt.

Description: In der Saison 1991/92 wurden erneut Seen in den Vestfold Hills (Wilkesland, Ost-Antarktis) untersucht. Ekho Lake ist hypersalin, heliothermal und meromiktisch; die größte Tiefe beträgt 42 m, die Salinität in diesem Bereich 180 %0. Entsprechend den unterschiedlichen Salzgehalten gibt es dort mindestens 3 Schichten, und die dazwischen liegenden Grenzflächen wirken wie Einwegspiegel und sammeln durch Reflektion nach unten die Sonneneinstrahlung. So wurde in der mittleren Schicht maximal + 18° C gemessen; während des antarktischen Winters fällt in den unteren Schichten die Temperatur nicht unter +13°C. Die Oxykline liegt in 24 m Tiefe. Organic Lake ist nur maximal 7.2 m tief, hat aber ebenfalls drei Schichten mit unten maximal 235 %0 Salinität. Während Ekho Lake normalerweise zufriert, gibt es auf dem Organic Lake nur sehr selten eine Eisbedeckung. Die Temperaturbedingunggnen sind hier auch wesentlich ungünstiger als bei Ekho Lake: selbst im Januar haben Tiefen unter 2 m noch negative Temperaturen. Aber die 1 m Schicht erreichte 16.5°C. Organic Lake hat einen Gehalt an gelöster organischer Substanz zwischen 23 und 45 mg/l-1. Der durchschnittliche Gehalt an OOC liegt dagegen bei Ekho Lake um 15 mg/l-1. (...)

Description: Mortality of two dogs, after exposure to water of a brackish lake on the German North Sea coast in 1990, is considered to be caused by a toxic Nodularia spumigena Mertens bloom.

Description: Ripe egg dimensions in the squid genus Illex are close to the minimum for cephalopods. The average diameter varies significantly depending on species (0.77–0.82 mm in I. coindeti , 0.75–0.88 mm in I. illecebrosus , and 0.96–1.04 mm in I. argentinus ), on geographical distribution intraspecifically, e.g. I. argentinus (0.96–0.97 mm in the shelf groups and 1.04 mm in the slope oceanic group), and between pre-spawning and spawning females of the summer-spawning shelf group of I. argentinus (0.97 and 0.92 mm, respectively). The potential fecundity (PF), defined as total oocyte stock both in the ovary and oviducts, depends on mantle length (ML in each species. It varies from 90 000 (ML = 150–160 mm) to 800 000 (ML = 230–250 mm) in I. coindeti , from 200 000 to 630 000 (ML = 220–280 mm) in I. illecebrosus , and from 75 000 (ML = 150–170 mm) to 1 200 000 (ML = 360–380 mm) in I. argentinus . It is possible to estimate the actual value of PF shortly before vitellogenesis begins and up to a start of spawning, when the diameter of the smallest oocytes exceeds 0.05 mm. The summer-spawning shelf females of I. argentinus release about of 70% of PF. Their spawning is intermittent and ripe egg production decreases over time with only a 50% replacement of the initial stock of vitelline oocytes and a decreasing volume of eggs at each release. Feeding activity decreases and the mantle wall and internal organs shrink once spawning commences. In spent animals, a degeneration of both vitelline and protoplasmic oocytes occurs. The squids genus Illex is one of typical r-strategists among the cephalopods.

Description: Viele Fischarten der Polarmeere schütz.eo sich vor dem Gefrieren durch die Synthese von makromolekularen Substanzen. Diese Moleküle sind meistens Proteine oder Glykoproteine (ANANfHANARA Y ANAN 1989). Die meisten antarlctischen Notolhenioidei sowie die arktischen und einige nord-boreale Dorschartige (Gadidae) besitzen sogenannte "antifreeze glycopeptides" (AFGP) der gleichen oder fast identischen Struktur. Dabei handelt es sich um Polymere verschiedener Länge des Glykotripeptids Alanin-Alanin-Threonin, wobei an jedes Threonin das Disaccharid Galaktose-N-Acetylgala.lctosamin gebunden ist. [...]

Description: Den Begriff 'Polynya' sucht man meist auch in anspruchsvollen Nachschlagewerken vergeblich. Er stammt aus dem Russischen und bezeichnet eine größere, sich über einen Zeitraum von Wochen bis Monaten erhaltende eisfreie Wasserfläche inmitten der zugefrorenen oder mit dichtem Treibeis bedeckten Meeresgebiete der Arktis und Antarktis. Ihre Größenausdehnung kann sich über hunderte und tausende von Quadratkilometern erstrecken. (...)

Description: The abundance and sedimentation of acantharia and their cysts was recorded in the water column and sediment traps in the East Greenland Sea in August-September 1990. Although acantharia constituted 〈1% of total suspended particulate organic carbon (POC) in the water column, up to 90% (average 55%) of the POC sedimenting in 100 m was present in the form of acantharian cysts during a 9 day drift experiment. Rapid dissolution of strontium sulphate, of which their shells and spines are constructed, was evidenced by their disappearance with depth in the water column, maximum dissolution occurring between 500 and 1000 m water depth. Mass encystment and sedimentation of this single group of sarcodine protozoa can have dramatic effects on, the measurement of particulate fluxes in the open ocean, and may be a recurrent phenomenon in the eastern North Atlantic.

Description: The plankton multiplier is a positive feedback mechanism linking the greenhouse effect and biological pump (Woods.J.D., Royal Commission on Environmental Pollution, 1990). As pollution increases the atmospheric concentration of carbon dioxide, the enhanced greenhouse effect induces radiative forcing of the ocean, which diminishes the depth of winter convection, reducing the annual resupply of nutrients to the euphotic zone and therefore the annual primary production. That weakens the biological pump, which contributes to oceanic uptake of CO2,. As the ocean takes up less CO2, more remains in the atmosphere, accelerating the rise in radiative forcing. We have used a mathematical model of the upper ocean ecosystem, based on the Lagrangian Ensemble method, to estimate the sensitivity of the biological pump to radiative forcing, which lies at the heart of the plankton multiplier. We conclude that increasing radiative forcing by 5 W m− (equivalent to doubling atmospheric CO2) reduces the deep flux of paniculate carbon by 10%. That sensitivity is sufficient to produce significant positive feedback in the greenhouse. It means that the plankton multiplier will increase the rate of climate change in the 21st century. It also suggests that the plankton multiplier is the mechanism linking the Milankovich effect to the enhanced greenhouse effect that produces global warming at the end of ice ages.

Description: We report major and trace element X-ray fluorescence (XRF) data for mafic volcanics covering the 15-Ma evolution of Gran Canaria, Canary Islands. The Miocene (12-lS^Ma) and Pliocene-Quaternary (0-6 Ma) mafic volcanics on Gran Canaria include picrites, tholeiites, alkali basalts, basanites, nephelinites, and melilite nephelinites. Olivine±clinopyroxene are the major fractionating or accumulating phases in the basalts. Plagioclase, Fe-Ti oxide, and apatite fractionation or accumulation may play a minor role in the derivation of the most evolved mafic volcanics. The crystallization of clinopyroxene after olivine and the absence of phenocrystic plagioclase in the Miocene tholeiites and in the Pliocene and Quaternary alkali basalts and basanites with MgO〉6 suggests that fractionation occurred at moderate pressure, probably within the upper mantle. The presence of plagioclase phenocrysts and chemical evidence for plagioclase fractionation in the Miocene basalts with MgO〈6 and in the Pliocene tholeiites is consistent with cooling and fractionation at shallow depth, probably during storage in lower-crustal reservoirs. Magma generation at pressures in excess of 3-0-3-5 GPa is suggested by (a) the inferred presence of residual garnet and phlogopite and (b) comparison of FeO1 cation mole percentages and the CIPW normative compositions of the mafic volcanics with results from high-pressure melting experiments. The Gran Canaria mafic magmas were probably formed by decompression melting in an upwelling column of asthenospheric material, which encountered a mechanical boundary layer at ~ 100-km depth.

Description: The subaerial portion of Gran Canada, Canary Islands, was built by three cycles of volcanism: a Miocene Cycle (8-5—15 Ma), a Pliocene Cycle (1-8-60 Ma), and a Quaternary Cycle (1-8-0 Ma). Only the Pliocene Cycle is completely exposed on Gran Canaria; the early stages of the Miocene Cycle are submarine and the Quaternary Cycle is still in its initial stages. During the Miocene, SiO2 saturation of the mafic volcanics decreased systematically from tholeiite to nephelinite. For the Pliocene Cycle, SiO2 saturation increased and then decreased with decreasing age from nephelinite to tholeiite to nephelinite. SiO2 saturation increased from nephelinite to basanite and alkali basalt during the Quaternary. In each of these cycles, increasing melt production rates, SiO2 saturation, and concentrations of compatible elements, and decreasing concentrations of some incompatible elements are consistent with increasing degrees of partial melting in the sequence melilite nephelinite to tholeiite. The mafic volcanics from all three cycles were derived from CO2-rich garnet lherzolite sources. Phlogopite, ilmenite, sulfide, and a phase with high partition coefficients for the light rare earth elements (LREE), U, Th, Pb, Nb, and Zr, possibly zircon, were residual during melting to form the Miocene nephelinites through tholeiites; phlogopite, ilmenite, and sulfide were residual in the source of the Pliocene-Quaternary nephelinites through alkali basalts. Highly incompatible element ratios (e.g., Nb/U, Pb/Ce, K/U, Nb/Pb, Ba/Rb, Zr/Hf, La/Nb, Ba/Th, Rb/Nb, K/Nb, Zr/Nb, Th/Nb, Th/La, and Ba/La) exhibit extreme variations (in many cases larger than those reported for all other ocean island basalts), but these ratios correlate well with degree of melting. Survival of residual phases at higher degrees of melting during the Miocene Cycle and differences between major and trace element concentrations and melt production rates between the Miocene and Pliocene tholeiites suggest that the Miocene source was more fertile than the Pliocene-Quaternary source(s). We propose a blob model to explain the multi-cycle evolution of Canary volcanoes and the temporal variations in chemistry and melt production within cycles. Each cycle of volcanism represents decompression melting of a discrete blob of plume material. Small-degree nephelinitic and basanitic melts are derived from the cooler margins of the blobs, whereas the larger-degree tholeiitic and alkali basaltic melts are derived from the hotter centers of the blobs. The symmetrical sequence of mafic volcanism for a cycle, from highly undersaturated to saturated to highly undersaturated compositions, reflects melting of the blob during its ascent beneath an island in the sequence upper margin-corelower margin. Volcanic hiatuses between cycles and within cycles represent periods when residual blob or cooler entrained shallow mantle material fill the melting zone beneath an island.

Description: In 1988 and 1989 the occurrence of external diseases in fish from the German part of the Wadden Sea was quantified. Thirty-two stations, located along seven transects including four estuaries, were sampled monthly or at 3-month intervals with shrimp trawlers: more than 124 000 fish were studied. Six percent of the seven dominant fish species of 〉 12 cm length were diseased. In fish species which complete their life cycle in the Wadden Sea (gobies, hooknose, eelpout, sea scorpion) the total disease incidence was below 0.4%. In whiting, plaice and sole it was between 0.5 and 2.5%, while 6–8% of smelt, cod, eel, dab and flounder suffered from external lesions. The incidence of most diseases increased with increasing fish length. Similar geographical patterns in prevalence were observed for: (1) two types of skeletal deformities, (2) lymphocystis in dab and flounder, (3) papillomatosis in smelt and dab and (4) several infectious ulcerative diseases. Most of these ulcerative diseases of cod and flounder occurred on central estuarine stations, suggesting an impact of the relatively low, but greatly variable salinity on disease development. Buccal granulomatosis of smelt and papillomatosis of eels showed the highest incidence in the Elbe estuary as the most heavily polluted region of the Wadden Sea. A causal relationship between disease development and pollution, however, is not yet clear and requires experimental evidence. The disease types found are ranked into three priority groups regarding their indicator value for a pollution monitoring on the basis of fish diseases. There is evidence that the total disease load of fish in the Wadden Sea is higher than in other shallow coastal regions outside the North Sea. Little is known of the effects of these diseases on single fish and fish populations. “Yellow pest” of cod, which was recorded for the first time during this survey, and which occurred with an incidence of up to 14% in single estuarine samples, causes the most serious lesions and is supposed to be lethal. In total, however, the effects of a number of pathogenic parasites on fish survival is considered to be more serious than that of deformities and infectious diseases.