Impact of a temporal salinity decrease on growth and nitrogen metabolism of the marine diatom Skeletonema costatum in continuous cultures

In 1987 effects of salinity fluctuations on growth of the centric diatom Skeletonema costatum (Greville) Cleve, isolated from the brackish Krammer estuary (SW Netherlands) in 1981, were investigated. Continuous cultures (12 h light: dark cycle) of S. costatum were adapted to constant salinity in natural (16.1) and synthetic (13.5) media. For several days the ammonium-limited cultures were exposed to a salinity fluctuation (minimum 4.8). Decreasing salinity caused an inhibition of photosynthesis, dark respiration and cell growth. Cellular pools of glucose decreased. While the carbohydrate content remained constant, the protein content increased slightly. Net carbon fixation was more inhibited than nitrogen assimilation. Ammonium accumulated during a salinity decrease; a total decline of the overcapacity of ammonium uptake was noticed and nitrogen limitation was relieved. Amino acid pools decreased, probably as a result of excretion (osmoregulation). The enzymes invoilved in ammonium assimilation showed an increased activity. Cellular activities were resumed during a salinity increase. Chlorophyll a increased; photosynthesis, ammonium uptake and growth were stimulated. The ammonium uptake capacity recovered completely; glutamic acid accumulation and increased glutamate-dehydrogenase (GDH) activity indicated supplementary ammonium assimilation via GDH. The activities of glutamine synthetase/glutamate synthase (GS/GOGAT) and GDH stabilized, and the cells returned to steady state under ammonium limitation.Communication no. 426 Delta Institute for Hydrobiological Research, Yerseke, The Netherlands     

Environmental Care in Agriculture: A Social Perspective

At its beginning, the European Union’s Common Agricultural Policy (CAP) did not include measures to guide farmers in preserving ecosystems. At the same time, the social context on the 1960s and 1970s did not encourage environmental care to become a priority. Since the 1980s, new social concern expressed alarm over ecology, recognizing that agriculture can pollute. These social changes moved the CAP to add measures that linked agriculture and environment. In order to study if the EU decision-makers have designed a CAP which responds to a new ethic that incorporates environmental care and social demands, two questions rise: whether the social image of agriculture as a polluting activity has changed; and whether farming performs the environmental functions demanded by society. To answer the previous questions, we have reviewed the environmental aspects added to the CAP, then a poll has been conducted and cluster method and classification tree models have been used to group respondents according to their opinions. The results show that the society ascribes great relevance to the environment for the future sustainability of the region, but they are not satisfied with the role of agriculture in producing environmental outputs.     

Wild plant species in bio-indication of radioactive-contaminated sites around Jaslovské Bohunice nuclear power plant in the Slovak Republic

In a long-term study of contaminated soil around Jaslovské Bohunice nuclear power plant (NPP), 24 species of local flora were used to show impact of serious accidents from 1976 to 1977. The 19-km-long banks of the Jaslovské Bohunice NPP wastewater recipient have been identified as contaminated by (137)Cs. In total, more than 67,000m(2) of riverbanks have been found as being contaminated at levels exceeding 1Bq (137)Csg(-1) of soil. Used phytotoxic and cytogenetic "in situ" tests were extended by analyses of pollen grains. Although the dose of some samples of radioactive soil was relatively high (322kBqkg(-1)) no significant impact on the biological level of tested wild plant species was observed.     

Identifying oceanic foraging grounds of sea turtles in the Atlantic using lead isotopes

Many species of marine organisms go through ontogenetic shifts that occur in unknown or inaccessible locations. Finding these areas is crucial to understand connectivity and resilience of populations, both of which have conservation implications. When extrinsic markers are not suitable to track organisms, intrinsic markers can be useful to infer the location of inaccessible areas where these cryptic stages occur. Our study focuses on the location of oceanic foraging areas of the cryptic early juvenile stage of green turtles, Chelonia mydas, in the Atlantic. Due to the small size of hatchlings, the use of telemetry is limited to short periods of time and small spatial ranges, which do not allow determining the location of oceanic foraging areas. We used lead (Pb) stable isotopes to determine the possible location of oceanic foraging areas of small green turtles in the Atlantic Ocean. Pb stable isotope ratios in the scute tissue deposited when turtles were in the oceanic habitat were compared to ratios of major sources of lead in the Atlantic and oceanic areas in the Atlantic to determine the location of oceanic foraging grounds. The Pb isotope ratios in the scute of oceanic-stage green turtles indicated that turtles use different regions in the Atlantic and that they are capable of transatlantic migrations. We compare the oceanic locations identified by this study with those suggested by two previous studies.     

Comparative phylogeography of marine cladocerans

We examined the population genetics of six species of marine cladocerans, using a ~600 bp fragment of the cytochrome oxidase subunit I gene sequence. Phylogenetic analysis revealed significant intraspecific, semi-allopatric phylogenetic breaks in four out of five species belonging to the Podonidae, supporting an ancient radiation and oceanic expansion for this group. By contrast, Penilia avirostris (Sididae) displayed no phylogeographic structure across a global sampling, suggesting a recent worldwide expansion. Our results also show a transoceanic distribution of identical or very similar haplotypes in several species of marine Cladocera, which may be interpreted as either natural transport or evidence of recent anthropogenic transport. If the latter is the case, marine cladocerans represent one of the first genetically documented cases of exotic or invasive marine zooplankton, likely an underreported group. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Sequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. EU675871–EU675924.     

Agricultural Sustainability from a Societal View: An Analysis of Southern Spanish Citizens

Sustainable agriculture refers to farming systems with economic, social, and environmental viability that must respond to citizens’ interests and concerns. However, European citizens are not satisfied with the Common Agricultural Policy (CAP) due to misinterpretation of their preferences. Because of this, the European agricultural model’s long-term viability is being questioned, especially after the European Commission’s CAP proposals in 2011. This paper examines European agriculture’s potential sustainability with regard to citizens’ preferences. First, focus groups and the Analytic Hierarchy Process are used to identify and quantify southern Spanish citizens’ preferences for farming. Second, socio-demographic features and opinions that determine preferences towards agriculture are studied by a multinomial logit model and a cluster analysis. A comparison is made between citizens’ preferences and the CAP aims because the CAP aims address all European farming. The main results indicate that agricultural economic, environmental, and social functions are equally important to the respondents in our study, even though the CAP prioritizes the economic ones. However, some citizen groups agree with the agricultural model designed by the CAP.     

Estimation and simulation for geospatial porosity and permeability data

Reservoir simulation of \(\hbox {CO}_2\) sequestration, energy recovery, and environmental contamination scenarios must be accompanied by uncertainty quantification. Typically this is done by stochastically modeling porosity and permeability fields, simulating realizations based on the model, and then numerically simulating flow and transport. The challenge is to generate simulated porosity and permeability fields with characteristics as similar as possible to those known of the reservoir under study. In this paper we focus on the first two steps above in analyzing a large 3-dimensional array of geospatial porosity data and using the results to produce simulated data with characteristics mimicking those of the original porosity observations. The spatial covariance is empirically approximated from horizontal cross sections of the data via a kernel principle component analysis yielding dimension reduction. Simulations in three dimensions are produced by linking consecutive parallel cross sections via conditioning on a small subarray of the data. The conditional simulations effectively reproduce observed channeling, an important large scale feature of interest in the sub-surface relevant to transport of contaminates. The original porosity data is non-Gaussian and requires additional analysis and transformation to generate both porosity and permeability fields.