ALBERT

Description: A highly sensitive and very simple spectrophotometric flow-injection analysis (FIA) method for the determination of iron(III) at low concentration levels is presented. The method is based on the measurement of absorbance intensity of the red complex at 410 nm formed by iron(III) and diphenylamine-4-sulfonic acid sodium salt (DPA-4-SA). It is a simple, highly sensitive, fast, and low cost alternative method using the color developing reagent DPA-4-SA in acetate buffer at pH 5.50 and the flow-rate of 1 mL min−1 with the sample throughput of 60 h−1. The method provided a linear determination range between 5 μg L−1 and 200 μg L−1 with the detection limit (3S) of 1 μg L−1 of iron(III) using the injection volume of 20 μL. FIA variables influencing the system performance were optimized. The amount of iron(III) and total iron in river and seawater samples was successfully determined. Repeatability of the measurements was satisfactory at the relative standard deviation of 3.5 % for 5 determinations of 10 μg L−1 iron(III). The accuracy of the method was evaluated using the standard addition method and checked by the analysis of the certified material Std Zn/Al/Cu 43 XZ3F.

Description: Our objective for this study was to evaluate the influence of preindustrial and expected future atmospheric CO2 concentrations (280 μatm and 700 μatm pCO2, respectively) on different life-cycle stages of the kelp Laminaria hyperborea from Helgoland (Germany, North Sea). Zoospore germination, gametogenesis, vegetative growth, sorus formation and photosynthetic performance of vegetative and fertile tissue were examined. The contribution of external carbonic anhydrase (exCA) to C-supply for net-photosynthesis (net-PS) and the Chla- and phlorotannin content were investigated. Female gametogenesis and vegetative growth of sporophytes were significantly enhanced under the expected future pCO2. rETR(max) and net-PS of young vegetative sporophytes tended to increase performance at higher pCO2. The trend towards elevated net-PS vanished after inhibition of exCA. In vegetative sporophytes, phlorotannin content and Chla content were not significantly affected by pCO2.

Description: In natural environments, marine biotas are exposed to a variety of simultaneously acting abiotic factors. Among these, temperature, irradiance and CO2 availability are major factors influencing the physiological performance of marine macroalgae. To test whether elevated levels of CO2 may remediate the otherwise reduced performance of uncalcified seaweeds under the influence of other stressful abiotic factors, we performed multi-factorial experiments with the red alga Chondrus crispus from Helgoland (North Sea) with two levels of CO2, temperature and irradiance: low and high pCO2 levels were tested in combination with either (1) optimal and low irradiances or (2) optimal and sub-lethal high temperatures for growth. Performance of C. crispus was evaluated as biomass increase and relative growth rates (RGR), gross photosynthesis and pigment content. Acclimations of growth and photosynthesis were measured after 4 and 8 days. Acclimation time was crucial for elucidating single or combined CO2 effects on growth and photosynthesis. Significant CO2 effects became evident only in combination with either elevated temperature or reduced irradiance. Growth and photosynthesis had divergent patterns: RGR and biomass significantly increased only under a combination of high pCO2 and elevated temperature; gross photosynthesis was significantly reduced under high pCO2 conditions at low irradiance. Pigment content varied in response to irradiance and temperature, but was independent of pCO2.

Description: Ocean acidification reduces the concentration of carbonate ions and increases those of bicarbonate ions in seawater compared with the present oceanic conditions. This altered composition of inorganic carbon species may, by interacting with ultraviolet radiation (UVR), affect the physiology of macroalgal species. However, very little is known about how calcareous algae respond to UVR and ocean acidification. Therefore, we conducted an experiment to determine the effects of UVR and ocean acidification on the calcified rhodophyte Corallina officinalis using CO2-enriched cultures with and without UVR exposure. Low pH increased the relative electron transport rates (rETR) but decreased the CaCO3 content and had a miniscule effect on growth. However, UVA (4.25 W m-2) and a moderate level of UVB (0.5 W m-2) increased the rETR and growth rates in C. officinalis, and there was a significant interactive effect of pH and UVR on UVR-absorbing compound concentrations. Thus, at low irradiance, pH and UVR interact in a way that affects the multiple physiological responses of C. officinalis differently. In particular, changes in the skeletal content induced by low pH may affect how C. officinalis absorbs and uses light. Therefore, the light quality used in ocean acidification experiments will affect the predictions of how calcified macroalgae will respond to elevated CO2.

Description: There is little use of cultivated kelp including Saccharina latissima (syn. Laminaria saccharina) in the European food industry, in contrast to the extensive use of Pyropia (syn. Porphyra) as Nori, e.g. in sushi restaurants. A major reason for this discrepancy is possibly the extremely high iodine content in laminarian species, i.e. 3–10 g I kg-1 dry weight, in contrast to the situation in Pyropia with its approximately 10 times lower iodine content. Another serious problem for commercial use of S. latissima from rope culture for food is the presence of epiphytic animals on the blades from May onwards as an unwanted food addition. This investigation presents data on iodine content in commercial samples of S. latissima, with indications of lower iodine values from rope cultivation in the Kattegat (Baltic) at reduced salinities, and in general from tank cultivation, possibly mainly due to rapid iodine depletion of seawater in the tanks. Boiling dried blades for several minutes in fresh water resulted in a reduction of the iodine content to approximately one third of the initial value after 2 min. Results from rope cultures in a Norwegian fjord showed the presence of epiphytic animals from early May onwards in the sea, which ruined the food quality of the blades, but the complete absence of such animals throughout the year in parallel tank-grown S. latissima, probably mainly due to mechanical prevention of larval settlement in tank tumble culture.

Description: From both ecological and biomedical viewpoints, it has become important to know whether the metabolites isolated from sponges are produced by symbiotic micro-organisms. Certain halogenated metabolites from Dysidea herbacea are localized in the symbiotic cyanobacterium Oscillatoria spongeliae. Recent studies concerning the origin of bioactive metabolites from lithistid sponges, some of which contain filamentous micro-organisms, are presented.

Description: To explore abundant marine ascidian bioresources, four species from two orders have been compared in their chemical compositions. After a universal separation of the animal body into two fractions, all tunics have been found rich in carbohydrate contents, while all inner body tissues are richer in proteins. Cellulose is present almost exclusively in the tunics and more in the order Stolidobranchia, while more sulfated polysaccharides are present in Phlebobranchia species. Almost all proteins are collagens with a high essential amino acid index and high delicious amino acid (DAA) content. All fractions also have high contents of good-quality fatty acids and trace minerals but low toxic element contents, with different sterols and glycosaminoglycans. There are species-specific characteristics observed for vanadium accumulation and sterol structures which are also meaningful for ascidian chemotaxonomy and resource exploitation. It is suggested that in addition to the present utilizations of tunics for cellulose production and of some species’ inner body tissues as human food, one should explore all species’ inner body tissues as human foods and all tunics as food or animal feed with the contained cellulose as dietary fiber. Collagens, sulfated polysaccharides, glycosaminoglycans, sterols and trace elements could be explored as byproducts for, e.g. pharmaceutical and chemical industries.

Description: Ocean warming and acidification may substantially affect the reproduction of keystone species such as Fucus vesiculosus (Phaeophyceae). In four consecutive benthic mesocosm experiments, we compared the reproductive biology and quantified the temporal development of Baltic Sea Fucus fertility under the single and combined impact of elevated seawater temperature and pCO2 (1100 ppm). In an additional experiment, we investigated the impact of temperature (0–25°C) on the maturation of North Sea F. vesiculosus receptacles. A marked seasonal reproductive cycle of F. vesiculosus became apparent in the course of 1 year. The first appearance of receptacles on vegetative apices and the further development of immature receptacles of F. vesiculosus in autumn were unaffected by warming or elevated pCO2. During winter, elevated pCO2 in both ambient and warmed temperatures increased the proportion of mature receptacles significantly. In spring, warming and, to a lesser extent, elevated pCO2 accelerated the maturation of receptacles and advanced the release of gametes by up to 2 weeks. Likewise, in the laboratory, maturation and gamete release were accelerated at 15–25°C relative to colder temperatures. In summary, elevated pCO2 and/or warming do not influence receptacle appearance in autumn, but do accelerate the maturation process during spring, resulting in earlier gamete release. Temperature and, to a much lesser extent, pCO2 affect the temporal development of Fucus fertility. Thus, rising temperatures will mainly shift or disturb the phenology of F. vesiculosus in spring and summer, which may alter and/or hamper its ecological functions in shallow coastal ecosystems of the Baltic Sea.

Description: Eine rasche Reduktion der Treibhausgasemissionen ist essentiell, wenn ambitionierter Klimaschutz erreicht werden soll. Bei der Abschätzung der dafür notwendigen Anstrengungen und der Bewertung des zukünftigen Beitrags von Technologien, die es erlauben, der Atmosphäre CO2 zu entziehen (negative Emissionstechnologien, NETs), gehen die Meinungen und die Interpretationen des aktuellen Sonderberichts des Weltklimarats stark auseinander. Interpretationen, die sich auf eher große verbleibende CO2-Budgets stützen und damit gleichzeitig die Rolle von NETs für die Erreichung des Temperaturziels herunterspielen, führen nicht zu verantwortungsvollen oder realistischen Einschätzungen der zukünftigen (Forschungs-)Herausforderung: Wir müssen bereits jetzt die Wirksamkeit verschiedener NETs, ihre Grenzen und ihre Wechselwirkungen verstehen, wenn die international angestrebten CO2-Konzentrationspfade realistisch sein sollen. Eine verfrühte Festlegung auf bestimmte NETs sollte vermieden werden. Sobald die Technologien, die sich als effizient erweisen, ausgereift sind, sollte der Umfang ihres Einsatzes durch die Einbeziehung in CO2-Emissionshandelssysteme oder CO2-Emissionssteuerregime bestimmt werden