Vertical distribution of zooplankton in a shallow peatland pond: the limiting role of dissolved oxygen

We investigated the diel vertical distribution patterns of microcrustacean zooplankton (Cladocera, Copepoda) in a shallow pond (max. depth: 70 cm) of the Öreg-turján peatland (Ócsa, Central Hungary) during three 24-h periods in July (19–20th), August (17–18th) and September (11–12th) 2011. Environmental variables showed remarkable vertical stratification. Oxygen concentration was close to zero in the entire water column from night until sunrise, while the lower strata (from 20 cm below the surface) were close to anoxic during all three diel cycles. It proved to be the main determinant of the vertical distribution of microcrustaceans. Accordingly, the highest proportion of individuals was present in the surface layer. Chlorophyll-a concentration and phytoplankton biomass were inversely distributed compared to zooplankton. Microcrustaceans (mainly Daphnia curvirostris) migrated to the middle layer only in August, which could be explained by a trade-off between food resources, dissolved oxygen (DO) and competition with littoral zooplankters. The diurnal density patterns of microcrustaceans suggested horizontal migration into the aquatic macrophytes during night, which could be a strategy to avoid Chaoborus predation. Our results show that strong vertical gradients of abiotic and biotic factors occur even in such shallow waterbodies. Among them, DO can maintain constant vertical aggregation of zooplankters by limiting their occurrence to the surface layers

Tests of multiple molecular markers for the identification of Great Spotted and Syrian Woodpeckers and their hybrids

Great Spotted and Syrian Woodpeckers (Dendrocopos major and D. syriacus) are known to hybridize in nature; however, the extent of this phenomenon is not known due to difficulties in hybrid detection based on plumage analyses. Here, we tested five markers (one mitochondrial and four nuclear) and a set of six microsatellite loci for the identification of these two Woodpeckers and their hybrids. Sequencing of DNA from 26 individuals of both Woodpeckers from different parts of their ranges: one allopatric (D. major; Norway) and two sympatric (Poland and Bulgaria) showed that both species can be clearly separated based on all sequence markers. The highest number of fixed nucleotide sites were found in the mtDNA control region and intron 5 of the transforming growth factor. Analyses of microsatellite data distinguished the two species, but all loci showed a large number of common alleles and their utility in identifying hybrids is therefore doubtful. According to the DNA sequence analyses, 2 out of 18 specimens within the sympatric range in Poland were identified as possible hybrids, most probably paternal backcrosses. Moreover, both hybrids are from synantropic populations (settled in cities), whereas none of the D. major sampled in forests and in its allopatric range (Norway) showed signs of an intermixed genotype. Further research on hybridization and introgression in woodpeckers is undoubtedly needed and could be useful for understanding ecological and ethological interactions among these species, particularly for D. syriacus, which is relatively rare in Europe

THE EFFECTS OF ADDITIVES ON THE PYROELECTRIC PROPERTIES OF T. G. S.

Nous résumons l'effet polaire permanent dû à la substitution d'alanine L sur les propriétés pyroélectriques de T. G. S. Nous expliquons les effets observés au moyen d'un modèle dans lequel le "switching" ferroélectrique est gêné par la perte de symétrie due à la substitution d'une molécule. D'autres additifs actifs et passifs peuvent être proposés à partir de ce modèle.The permanent poling effects of L-alanine substitution on the pyroelectric properties of T. G. S. are summarized. The observations are explained in terms of a structural model in which ferroelectric switching is impeded by the lack of the required prototypic symmetry in the substituent molecule. Other active and passive additives may be proposed from the model

Staurosira grigorszkyi nom. nov. (Bacillariophyceae) an araphid diatom from Lake Balaton, Hungary, with notes on Fragilaria hungarica Pantocsek.

Abstract: Epilithon and epiphyton samples collected from Lake Balaton (Hungary) in 2006 and 2007 contained, as dominant, specimens similar to those described in 1902 by Pantocsek as Fragilaria hungarica. Since Pantocsek had previously used the name F. hungarica in 1892 for a fossil taxon from Deménd (Slovakia), the Lake Balaton specimens required a new name. Additionally, information collected during this study, using light (LM) and scanning electron microscopy (SEM), supports the transfer of the specimens from Lake Balaton to the genus Staurosira Ehrenberg. The nomenclatural consequences from Pantocsek’s dual use of the name F. hungarica, are solved herein by the proposal of the new name Staurosira grigorszkyi nom. nov