Biomanipulation of hypereutrophic ponds: when it works and why it fails

Phytoplankton, zooplankton, submerged vegetation and main nutrients have been monitored in 48 eutrophic ponds from the Brussels Capital Region (Belgium) between 2005 and 2008. Nine ponds have been biomanipulated in order to improve their ecological quality and prevent the occurrence of noxious cyanobacterial blooms. The 4-year study of a large number of ponds allowed identification of the factors having the strongest influence on phytoplankton growth. Continuous monitoring of the biomanipulated ponds allowed the significance of changes caused by biomanipulation to be tested as well as the main reasons of biomanipulation successes and failures to be elucidated. The main factors controlling phytoplankton in the ponds studied appeared to be grazing by large cladocerans and inhibition of phytoplankton growth by submerged vegetation. Biomanipulation resulted in a significant decrease in phytoplankton biomass in general and biomass of bloom-forming cyanobacteria in particular that were associated with a significant increase in large Cladocera density and size. In six out of nine ponds biomanipulation resulted in the restoration of submerged vegetation. The maintenance of the restored clearwater state in the biomanipulated ponds was strongly dependent on fish recolonisation and nutrient level. In the absence of fish, the clearwater state could be maintained by submerged vegetation or large zooplankton grazing alone. In case of fish recolonisation, restoration of extensive submerged vegetation could buffer, to a considerable degree, the effect of fish except for ponds with high nutrient levels.     

Transport of nitrogen oxides, carbon monoxide and ozone to the Alpine Global Atmosphere Watch stations Jungfraujoch (Switzerland), Zugspitze and Hohenpeissenberg (Germany), Sonnblick (Austria) and Mt. Krvavec (Slovenia)

The Alpine stations Zugspitze, Hohenpeissenberg, Sonnblick, Jungfraujoch and Mt. Krvavec contribute to the Global Atmosphere Watch Programme (GAW) of the World Meteorological Organization (WMO). The aim of GAW is the surveillance of the large-scale chemical composition of the atmosphere. Thus, the detection of air pollutant transport from regional sources is of particular interest. In this paper, the origin of NO_x (measured with a photo-converter), CO and O₃ at the four Alpine GAW stations is studied by trajectory residence time statistics. Although these methods originated during the early 1980s, no comprehensive study of different atmospheric trace gases measured simultaneously at several background observatories in the Alps was conducted up to present.The main NO_x source regions detected by the trajectory statistics are the northwest of Europe and the region covering East Germany, Czech Republic and southeast Poland, whereas the main CO source areas are the central, north eastern and eastern parts of Europe with some gradient from low to high latitudes. Subsiding air masses from west and southwest are relatively poor in NO_x and CO.The statistics for ozone show strong seasonal effects. Near ground air masses are poor in ozone in winter but rich in ozone in summer. The main source for high ozone concentration in winter is air masses that subside from higher elevations, often enhanced by foehn effects at Hohenpeissenberg. During summer, the Mediterranean constitutes an important additional source for high ozone concentrations.Especially during winter, large differences between Hohenpeissenberg and the higher elevated stations are found. Hohenpeissenberg is frequently within the inversion, whereas the higher elevated stations are above the inversion.Jungfraujoch is the only station where the statistics detect an influence of air rich in CO and NO_x from the Po Basin.     

Modelling spatial patterns of correlations between concentrations of heavy metals in mosses and atmospheric deposition in 2010 across Europe

Background

This paper aims to investigate the correlations between the concentrations of nine heavy metals in moss and atmospheric deposition within ecological land classes covering Europe. Additionally, it is examined to what extent the statistical relations are affected by the land use around the moss sampling sites. Based on moss data collected in 2010/2011 throughout Europe and data on total atmospheric deposition modelled by two chemical transport models (EMEP MSC-E, LOTOS-EUROS), correlation coefficients between concentrations of heavy metals in moss and in modelled atmospheric deposition were specified for spatial subsamples defined by ecological land classes of Europe (ELCE) as a spatial reference system. Linear discriminant analysis (LDA) and logistic regression (LR) were then used to separate moss sampling sites regarding their contribution to the strength of correlation considering the areal percentage of urban, agricultural and forestry land use around the sampling location. After verification LDA models by LR, LDA models were used to transform spatial information on the land use to maps of potential correlation levels, applicable for future network planning in the European Moss Survey.

Results

Correlations between concentrations of heavy metals in moss and in modelled atmospheric deposition were found to be specific for elements and ELCE units. Land use around the sampling sites mainly influences the correlation level. Small radiuses around the sampling sites examined (5 km) are more relevant for Cd, Cu, Ni, and Zn, while the areal percentage of urban and agricultural land use within large radiuses (75–100 km) is more relevant for As, Cr, Hg, Pb, and V. Most valid LDA models pattern with error rates of <?40% were found for As, Cr, Cu, Hg, Pb, and V. Land use-dependent predictions of spatial patterns split up Europe into investigation areas revealing potentially high (=?above-average) or low (=?below-average) correlation coefficients.

Conclusions

LDA is an eligible method identifying and ranking boundary conditions of correlations between atmospheric deposition and respective concentrations of heavy metals in moss and related mapping considering the influence of the land use around moss sampling sites.

     

Comparison of the statolith structures of <Emphasis Type=Italic>Chironex fleckeri</Emphasis> (Cnidaria,Cubozoa) and <Emphasis Type=Italic>Periphylla periphylla</Emphasis> (Cnidaria,Scyphozoa): a phylogenetic approach

The rhopalia and statocysts of Periphylla periphylla (Péron and Lesueur in Ann Mus Hist Nat Marseille 14:316–366,1809) and Chironex fleckeri Southcott (Aust J Mar Freshw Res 7(2):254–280 1956) were examined histologically and showed several homologous characteristics. Differences in sensory area distribution could be connected to a slightly different functionality of equilibrium sensing. In P. periphylla, the statoliths (crystals) grow independently of each other; whereas in C. fleckeri, one large crystal covers the smaller ones. The structures of both statoliths were examined in detail with single-crystal diffraction, microtomography and diffraction contrast tomography. The single compact statolith of C. fleckeri consisted of bassanite as was previously known only for other rhopaliophoran medusae. An origin area with several small oligocrystals was located in the centre of the cubozoan statolith. The origin areas and the accretion of statoliths are similar in both species. Our results lead to the assumption that the single bassanite statolith of C. fleckeri (Cnidaria, Cubozoa) is a progression of the scyphozoan multiplex statolith. It is therefore suggested that the Cubozoa are derived from a scyphozoan ancestor and are a highly developed taxa within the Rhopaliophora.     

Embryonic abnormalities and organochlorine contamination in double-crested cormorants (Phalacrocorax auritus) and Caspian terns (Hydroprogne caspia) from the upper Great Lakes in 1988

Persistent organochlorine contaminants including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) were determined in eggs with normal and deformed embryos collected in 1988 from different colonies during an epizootiological survey of double-crested cormorants (Phalacrocorax auritus) and Caspian terns (Hydroprogne caspia) from the upper Great Lakes. PCBs and p,p'-DDE were found in the highest concentrations in eggs of both species. The residue pattern of PCB isomers and chlordane compounds suggested that double-crested cormorants have greater metabolic capacity to degrade contaminants than Caspian terns. According to the toxicity evaluation using the 2,3,7,8-TCDD equivalents (TEQs) approach, non-ortho coplanar PCBs contributed much more toxicity than PCDDs and PCDFs. Total TEQ of dioxin-like compounds was likely associated with occurrence of live-deformed embryos in double-crested cormorants eggs. The toxic effects of these contaminants were also estimated in Caspian tern eggs, where elevated levels of coplanar PCBs, PCDDs and PCDFs were observed in concordance with increased rate of anomalies in eggs during a breeding season in the Great Lakes.     

对美洲热带湿润低地次生林管理的看法

在休闲农地上重新长出的次生林,尽管广被忽视,仍是美洲热带低地重要的景观单元.这些在私人占用土地中"新"的森林资源不是来源于境况较好农民的非持续性的大牧场就是来源于资源贫乏农民的耕种/休闲体系.