ALBERT

Description: The mechanism of sulfate assimilation was investigated in Rhodopseudomonas sulfidophila, a bacterium able to grow either photoautotrophically, with sulfide as electron donor, or photoheterotrophically with sulfate as sole sulfur source. ATP sulfurylase, adenosine-5′-phosphosulfate kinase, 3′-phosphoadenosine-5′-phosphosulfate sulfotransferase, thiosulfonate reductase and cysteine synthase were present. Reduced sulfur compounds, especially sulfide and sulfite repressed all steps of sulfate activation and reduction including sulfate uptake. Adenosine-5′-phosphosulfate kinase activity in contrast to the other activities was high in the presence of cysteine or reduced glutathione in the growth medium. Sulfur was incorporated into the cellular sulfolipid from sulfate and also from reduced sulfur compounds like cysteine and thiosulfate. The activity of 3′-phosphoadenosine-5′-phosphosulfate sulfotransferase was rapidly lost during gel filtration or dialysis. From comparison with other sulfotransferases and from the specific cofactor requirement for the enzyme of R. sulfidophila it is concluded that two different low molecular weight cofactors are required in this system. A reaction sequence is proposed involving thioredoxin as the reductant of another dialysable low molecular weight cofactor, that binds to the protein.

Description: Ammonium regeneration, nutrient uptake, bacterial activity and primary production were measured from March to August 1980 in Bedford Basin, Nova Scotia, Canada, a eutrophic environment. Rates of regeneration and nutrient uptake were determined using 15N isotope dilution and tracer methodology. Although primary production, nutrient uptake and ammonium regeneration were significantly intercorrelated, no relationship was detected between these parameters and heterotrophic activity. The average contribution of ammonium to total nitrogen (ammonium+nitrate) uptake was similar in the spring and in the summer (approximately 60%). On a seasonal average basis, 36% of the phytoplankton ammonium uptake could be supplied by rapid remineralization processes. In spite of the high average contribution of NH4 regeneration to phytoplankton ammonia uptake, there is indirect evidence suggesting that other NH4 sources may occasionally be important.

Description: Anhand hundertjähriger Meßreihen wurden langfristige Salzgehaltsänderungen in der Unterweser und ihre möglichen Ursachen untersucht. Dabei wurde angestrebt, die natürlichen und die anthropogenen Einflüsse auf den Salzgehalt zu trennen. Trotz des unvollständigen Datensatzes konnten der Einfluß des Einzugsgebietes und Salzgehaltsschwankungen des angrenzenden Meeresgebietes nahezu eliminiert werden. Wegen der langzeitigen Änderungen der Gezeiten in der Nordsee waren genaue Aussagen über die Auswirkung der in den letzten hundert Jahren in der Unterweser durchgeführten Baumaßnahmen auf den Salzgehalt nicht möglich. Unsere Ergebnisse geben Hinweise für moderne Meßnetze zur Bestimmung der Wasserqualität.

Description: A suite of marble specimens from the Sierra Alhamilla (Spain), deformed to large strains under natural conditions at about 300° C shows distinct variations in microstructure and fabrics. It can be demonstrated that the development of crystallographic preferred orientations and grain shape fabrics are strongly dependent on recrystallized grain size. This is interpreted to reflect the relative importance of various deformational mechanisms. Superplasticity seems to have a sharp upper grain size limit at 10–15 /smm. Within the power law creep regime, deformation in fine grained aggregates is probably dominated by diffusional, in coarser ones by dislocation mechanisms. The transition is a gradual one, and may span a grain size range of 30 /sm.

Description: Statoliths of the short-finned squid Illex illecebrosus were chemically analyzed to define their chemical composition and surveyed by scanning electron microscope to differentiate internal structural patterns. X-ray diffraction data demonstrated that L Illecebrosus statoliths were composed principally of CaCQ in the aragonite crystal form. The crystals occurred in a protein matrix to form incremental patterns which radiated from the nucleus to the edge of the statoliths. The protein matrix comprised approximately 5% of the statolith by weight. The protein was principally composed of acidic amino acids. A high abundance of aspartic acid in the protein matrix indicated that the matrix would function as a template in the initiation and acceleration of the crystal growth of CaCO. The rhythmic microstructural patterns, constructed of aragonite crystals in the protein matrix, wer e suggested to be daily in formation and subsequent growth estimations were in agreement with known life history information. The stable isotopic composition of the carbonate of L illecebrosus statoliths suggested that oxygen may be deposited in isotopic equilibrium with the surrounding environment while carbon appeared to be related to biological processes. The information recorded in the statotiths as incremental growth and stable isotopic composition could provide valuable insights into the ecological history of squid.

Description: Seismic, lithostratigraphic, faunal, and isotopic evidence from the western and northern North Atlantic indicates that formation of northern sources for strongly circulating bottom water began in the late Eocene to early Oligocene. The widely distributed reflector R4 correlates with an unconformity eroded along basin margins at the Eocene/Oligocene boundary. This change in abyssal regime also correlates with a major benthic foraminiferal turnover in the deep southern Labrador Sea (DSDP Site 112) and with a faunal reorganization in the Bay of Biscay. The principal bottom-water source probably was of Arctic origin; it entered the Norwegian Sea following separation of Greenland and Spitsbergen and flowed south across the Greenland-Scotland Ridge through the Faeroe-Shetland Channel and possibly across a sill east of Greenland. This flow may have been supplemented by dense Arctic water entering the basin via Nares Strait and Baffin Bay, and by cooling and sinking of saline surface water south of the Greenland-Scotland Ridge and in the Labrador Sea. Current-controlled sedimentation and erosion, often of a chaotic nature, continued through the Oligocene above reflector R4, but the general intensity of abyssal circulation is thought to have decreased. Above reflector R2 (upper lower Miocene) current-controlled sedimentation became more coherently developed, and a major phase of sedimentary drift development was initiated. We interpret this to be a result of a further general reduction and especially a stabilization of the abyssal circulation, possibly linked with degeneration of numerous fracture-zone conduits that previously funnelled bottom water across the Reykjanes Ridge. The gross nature of the circulation has not changed substantially since the middle Miocene, although it has been punctuated by further climatic and tectonic events.

Description: Natural phytoplankton from Lake Constance was exposed to competition experiments in continuous culture at 6 different molar rations of PratioSi as potentially limiting nutrients. As predicted by theory there was competitive exclusion of all species but one at single nutrient limitation, and coexistence of two species in steady state when P was limiting for one and Si for the other species. In one case coexistence of three species occurred. Equilibrium species composition, which stabilized after 3 to 6 weeks of cultivation, was independent of the species composition of the inoculum and only controlled by the nutrient regime. Comparability of experimental results and field observations is discussed.

Description: Seasonal variations in bacterial populations (total number, biomass, biomass-spectrum, number of dividing cells) as well as in concentrations and decomposition rates of particulate organic material were followed in a sandy mud sediment of the Western Kiel Bight (Baltic Sea; FRG). The strong seasonal variations observed could be traced back to the effect of certain ecological situations and events in the sediment from which the input of the phytoplankton blooms in autumn and spring, respectively, the accumulation of organic material during winter, and the spring development of the benthic fauna turned out to be the most important. Bacterial carbon net production following the breakdown of the phytoplankton blooms ranged between 9 μg (autumn) and 16 μg (spring) per g of dry weight sediment per day. The consequences of shifts in the size composition of the bacterial populations as well as the importance of the measurement of enzymatic decomposition rates of particulate organic material in sediments are demonstrated and discussed in relation to the events mentioned above

Description: The response of the benthos to the break up of anoxia in the Kiel Bight (Western Baltic Sea), and to three succeeding events of “external” food supply, consisting of a settled autumn plankton bloom, resuspended matter and macrophyte input during winter, and of a sedimented spring phytoplankton bloom, is described on a community level. The first input of oxygen broke up anoxic conditions and made stored food resources available to decomposition. This “internal” food supply, mainly consisting of protein (folin positive matter), was followed by a drastic increase in heat production and ATP-biomass and caused a period of low redox potential, which lasted for several weeks. During this phase, a plankton bloom (dinoflagellates and diatoms) settled to the sea floor. Although there was an immediate response of benthic activity, this food input was not completely consumed by the strongly disturbed benthic community. During winter resuspended matter and the input of macrophyte debris caused another maximum in benthic activity and biomass despite the low temperature. The response to sedimentation of cells from a diatom bloom during mid March was also without any time lag and was consumed within 5–6 wk. A comparison of the amount of particles collected in a sediment trap with the increase of organic matter in the sediment demonstrated that the sediment collected four times (autumn) and seven to eight times (spring) more than measured by the sediment trap. Strong indications of food limitation of benthic activity were found. During autumn and winter these indications were caused more by physical than by biological processes. The three events of “external” food supply caused a temporary shift in the type of metabolism towards fermentation processes and reduced the redox potential. In spring the development of the benthic community was still being strongly influenced by the events of the preceding summer and autumn.

Description: This paper brings together widely scattered information on sexual reproduction in scleractinian corals. It includes a review of information and ideas on sex determination, gametogenesis, gametogenic cycles, fertilization and embryonic development, spawning and planula release, larval behavior, settlement and metamorphosis. The review deals with corals from different habitats and organismic assemblages, including tropical reef corals, temperate water corals, solitary and colonial forms. A summary table of coral species and their known reproductive characteristics is presented.

Description: The internal shell of the cuttlefish, which acts as a rigid buoyancy tank, is structured to combine high compressive strength — since it must withstand the external hydrostatic pressure — with minimum weighT. The micro-architecture of cuttlebone has been examined by electron microscopy and the relevance of the structure to the mechanical duties required of the shellin vivo are briefly discussed. The inorganic calcareous structure is associated with an organic component which may act as a template for mineralization.