L'andamento della gravita' sui mari

Riassunto Usufruendo delle più recenti serie di misure della gravità, l'A. esamina la distribuzione di tale grandezza lungo alcuni profili degli Oceani Atlantico, Pacifico e Indiano, traendone diverse conclusioni e confermando precedenti risultati.

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Zusammenfassung Auf Grund der neueren Reihen der Schweremessungen auf dem Meer, untersucht der Verf. die Schwereverteilung längs einiger Profile des Atlantischen, des Pazifischen und des Indischen Ozeans; daraus zieht er einige Schlussfolgerungen und bestätigt andere schon bekannte Ergebnisse.

     

Tektonik und Lithogenese

Ohne Zusammenfassung     

Die geophysikalischen Grundlagen der Verschiebungstheorie

Ohne Zusammenfassung     

Northern Adriatic Rocky Reef Fishes at Low Winter Temperatures

Abstract. The behavioural ecology of certain northern Adriatic fishes was observed from January to April at a water temperature of 7–11 ^oC. The fishes studied here do not migrate to deeper waters. Most of the benthic fishes show a similar distribution over the substrate in winter and in summer; in winter, however, they are very inactive and hide in the substrate. Suprabenthic fishes aggregate in littoral caves where they form dense, inactive, mixed aggregations. Certain hemipelagic and pelagic fishes join to form very dense aggregations at specific sites in the open waters of bays. Littoral predators display high feeding activity at a time when their prey is inactive. I present a hypothesis concerning possible implications of seasonally cyclic environmental temperatures for a sympatric community of non-migrating fishes.     

Element-specific detectors for liquid chromatography: The determination of arsenic compounds

Systems for the determination of trace element compounds consisting of liquid chromatographs (LC) (high pressure liquid chromatographs, ion chromatographs) and graphite furnace atomic absorption spectrometers (GFAAS) or inductively coupled argon plasma emission spectrometers (ICP) as single- or multi-element-specific detectors are described. The applications of these systems to the determination of arsenic compounds are reviewed. The absolute detection limits of these systems for arsenic are in the low nanogram range. These detection limits can probably be improved by two-three orders of magnitude by coupling an inductively coupled argon plasma-mass spectrometer instrument to the liquid chromatograph. The advantages and drawbacks of the LC-GFAAS and LC-ICP systems are outlined. These systems can separate and identify trace element compounds that are kinetically or thermodynamically stable under the conditions of the chromatography. Labile compounds cannot be determined by these systems. Wide application of these systems to problems of trace element research will lead to the identification of hitherto unknown trace element compounds, to a better understanding of the nutritional and toxic properties of trace element compounds, and to a better definition of trace element cycles.     

Mud transportation on a steep shelf,Rio de La Plata shelf,Puerto Rico

Hurricanes David (August 29–30, 1979) and Frederick (September 2–5, 1979) caused major flooding of the Rio de La Plata in northern Puerto Rico. A thin mud layer was deposited across the narrow insular shelf adjacent to the river mouth. Within 5 months, fair-weather shelf-winnowing processes moved the mud layer entirely from the shelf, 0.5 to 2 km to the shelf break at the 50-m contour and beyond. The process of mud movement is termed “mud hopping.”     

The Diets in Four Pacific Tube Blennies (Acanthemblemaria: Chaenopsidae): Lack of Ecological Divergence in Syntopic Species

Abstract. The diets of three syntopic Gulf of California Acanthemblemaria (A. balanorum, A. crock-eri and A. macrospilus) and A. castroi from the Galapagos Island are nearly uniformly composed of harpacticoid copepods and other small benthic-vagile or planktonic crustaceans. On occasion, large prey items such as crabs or other small fishes are taken. HORN'S index of niche overlap indicates that the three syntopic Acanthemblemaria are not separated along the food resource utilization axis. Slight variations in diets among the syntopic species seem to be related to differences in degree of microhabitat specialization.     

Feeding Ecology of three Populations of Blennius incognitus BATH 1968 (Pisces: Teleostei: Blenniidae) during the Reproduptive Period and under Human Influence

Abstract. Samples of Blennius incognitus from three differently polluted locations on the Istrian west coast (Adriatic Sea, Yugoslavia) were collected in early July during the spawning season. The gut content was analyzed employing the occurrence and point (relative volumetric) method. This fish grazes the surface of the rocky substratum. Inhabiting small benthic animals are ingested together with algae and detritus. The diet depends on the composition and condition of the covering phytal and its inhabiting fauna. A decrease of available animal food seems to intensify grazing on the substrate. A sexual dimorphism in the feeding habit during the reproductive period exists. Females feed more on animals; males feed more on substrate and in cases also on eggs of their own species.