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Oceanologia
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2008
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tom 50
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nr 4
557-575
Interaction between continental and marine end-members gives rise to the natural biogeochemical processes in Sharm Al-Kharrar, a lagoon in the arid Red Sea region. Twenty-nine surface sediment samples were collected from the area and their mud fraction analysed for grain size, OC, CaCO3, mineralogy and elemental composition. The mud fraction consisted of a mixture of siliciclastic/calcareous materials, dominated by silt size materials and characterised by low OC (average 0.71% ±0.13); CaCO3 varied widely, with an average of 45% ±18. Concentrations of Al, Fe, Mn, Cu, Ni, Cr, V and Ba showed a wide range of variation throughout the Sharm. The results were normalised to Al and subjected to cluster analysis in order to examine the relations between the mineralogy and the elemental composition. The contents of Al, Fe, Mn, Cu, Ni, Cr, V and Ba appeared to be influenced by the mixing of the two end-members in addition to the physiochemical processes associated with the mixing between episodic freshwater flooding and seawater. Zn was the single element that showed a slight departure from the mixing model.
During the parasitological examination of the barn owl Tyto alba (Gmelin), from Mar Chiquita coastal lagoon in Argentina, specimens belonging to Synhimantus (S.) laticeps (Rudolphi, 1819) Railliet, Henry et Sissof, 1912 were obtained. Comparison of measurements of present specimens with Cram and Smogorzhevskaya’s description of the same species, revealed several dissimilarities in the metrical features which cannot be considered great enough to create a new species. This new record of S. (S.) laticeps represents the first citation of this nematode from South America, and contributes to the knowledge of the morphology of this species, giving complete measurements and a detailed description of spicules. In addition, morphological and evolutionary considerations regarding fourth larval stages and subadults of S. (S.) laticeps, are also presented in this paper.
Evaluated direct methods for estimating primary production are both a precondition and a supplement for modeling scenarios in a eutrophicated and changing coastal ecosystem. Analyses of phytoplankton succession, integral primary production and potential limitation of phytoplankton growth of the shallow brackish Darss-Zingst Bodden chain indicate the extraordinary importance of colony-forming nanophytoplankton for primary productivity. Respective studies began in the 1990s. Exemplary studies focus on the contribution of individual aggregates and phytoplankton colonies to potential primary production as well as the microscale visualization and seasonal variability of extracellular enzymatic phosphate hydrolysis. Results from these studies suggest that an inhomogeneous distribution of productivity and limitation is relevant to the pelagic zones. This paper discusses the effect of heterogeneity on ecosystem behavior in this specific trophy succession state in the context of a future strategy to supplement bulk methods for productivity and limitation analyses especially for barely distinguishable phytoplankton species in euthropicated coastal waters.
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