Mesozooplankton distribution,metabolism and grazing in an anticyclonic slope water oceanic eddy (SWODDY) in the Bay of Biscay

Mesozooplankton distribution, metabolism and feeding were investigated in the slope water oceanic anticyclonic eddy (SWODDY) AE6 during the cruise Gigovi-0898, which was conducted in August 1998 in the Bay of Biscay. According to the distribution of isotherms at 200 m depth, the sampling area was divided into three zones: SWODDY centre (C), edge (E) and outside the SWODDY (O). Multivariate analysis identified four different zooplankton assemblages. Such separation was closely related to the structure of the SWODDY, with each grouping associated to a particular zone of this mesoscale structure. Thus, two of the groups were located at the SWODDY centre and outside (groups C and O, respectively), whereas the two remaining station groupings (T_WE and T_NS) were situated at the SWODDY margin. The assemblages C and O differed clearly from each other in their taxonomic composition. In contrast, T_WE and T_NS were separated because of the differences observed in numerical abundance rather than by a different composition. Some taxa were found exclusively outside the SWODDY, while others were confined to the centre, suggesting a large degree of isolation of the SWODDY with respect to the surrounding waters. Phytoplankton and mesozooplankton biomass followed a similar pattern, with highest values in the SWODDY centre, although the differences between zones were significant only for phytoplankton. The highest grazing impact for both phytoplankton standing stock (3.4%) and primary production (12.7%) was observed outside the SWODDY. Ammonium released by mesozooplankton accounted for between 25.3% (outside the SWODDY) and 44.4% (SWODDY centre) of total phytoplankton nitrogen demands. The percentage of total phosphorus required to be fulfilled by phosphate excretion ranged from 14.0% at the edge to 17.5% outside. Mesozooplankton underwent intense vertical migrations, especially at the SWODDY edge. The role of the mesozooplankton in the biological pump releasing metabolic end-products below 200 m at night time is proposed as one of the main sources of downward export of biogenic material in these systems.Communicated by S.A. Poulet, Roscoff     

Radioactivity concentration in liquid and solid phases of scale and sludge generated in the petroleum industry

Scales and sludge generated during oil extraction and production can contain uranium, thorium, radium and other natural radionuclides, which can cause exposure of maintenance personnel. This work shows how the oil content can influence the results of measurements of radionuclide concentration in scale and sludge. Samples were taken from a PETROBRAS unit in Northeast Brazil. They were collected directly from the inner surface of water pipes or from barrels stored in the waste storage area of the E&P unit. The oil was separated from the solids with a Soxhlet extractor by using aguarras at 90+/-5 degrees C as solvent. Concentrations of 226Ra and 228Ra in the samples were determined before and after oil extraction by using an HPGe gamma spectrometric system. The results showed an increase in the radionuclide concentration in the solid (dry) phase, indicating that the above radionuclides concentrate mostly in the solid material.     

Debates on Sustainable Development: Towards a Holistic View of Reality

The paper analyzes the concept of sustainable development in the light of the different interpretations existing on the issue since its appearance and establishment as an ideal to lead humanity’s line of progress. Within these interpretations, a characteristic generation of diverse debates can be appreciated, arising from different perspectives, academic as well as ideological, aiming at describing, clarifying and determining their conceptual reach. Based on these facts a model of categorization for these debates has developed, a model in which interpretations generated on the concept of sustainable development were catalogued into four realms: conceptual, contextual, academic and geopolitical. The configuration of these four areas of debate, as well as the recognition of the diversity of interpretations existing on sustainable development, is a reflection of the intrinsic complexity of the phenomena, which affect the natural and social world, both at the local and global level. The analysis of this complexity is based on the subjectivity, which is inherent to the interpretation of these phenomena, with permanent reference to the cultural context from which the diverse discourses were structured. This global perspective on the state-of-the-art controversy concerning the idea of sustainable development as an articulatory axis reveals the necessity of building epistemological models, which can give a new direction to scientific research. From these new models, based on the analysis of the holistic character of reality, the subjective and the objective must be integrated in the generation of knowledge, which contributes usefully to the unceasing reconstruction of our world-(view). Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Evaluation of compliance with national legislation on emissions in Portugal

More than 13 years after publication of the first air quality laws in Portugal and more than 10 years after the publication of the respective emission limits, it seems appropriate to analyze the degree of compliance by the Portuguese manufacturing industry. Using the data from emission measurements made regularly by the Instituto de Soldadura e Qualidade, the only officially accredited laboratory according to standard ISO 17025, I analyzed a set of approximately 400 sources in terms of compliance with the emission limits regarding total suspended particulates, sulfur dioxide, nitrogen oxides, and volatile organic compounds. I evaluated compliance through a nondimensional parameter and plotted it versus the emission flow rate to derive conclusions: the results indicate that emission limits are generally met regarding sulfur dioxide and nitrogen oxides but not for the other pollutants considered in this study. However, noncompliance occurs mainly for very low emission flow rates, which suggests some alterations in the emission limits, which are being revised at the moment. These alterations will include the exemption of measurements in minor sources.     

Ontogenic changes of amino acid composition in planktonic crustacean species

Changes in amino acid composition (AAC) during ontogeny of some planktonic crustacean species commonly found in fresh and brackish coastal waters were compared. For these comparisons two calanoid copepods (Eurytemora velox and Calanipeda aquae-dulcis), two cyclopoid copepods (Diacyclops bicuspidatus odessanus and Acanthocyclops robustus) and two Daphnia (Daphnia pulicaria and Daphnia magna) species were selected. A discriminant analysis was performed to determine whether there were significant differences between the AAC of the different stages of each species. Results show gradual changes in AAC during ontogeny of the copepod species. Calanoids showed the greatest differences in AAC between stages, followed by cyclopoids. Gradual changes in AAC were due to the increase in some amino acids such as alanine, valine, glutamic acid, glycine, arginine, proline and tyrosine from nauplii to adults. The latter showed a remarkable increase in all copepod species. In contrast, Daphnia species showed a relatively constant AAC during development, with only minor changes being detected, and not related with ontogeny. Differences in the physico-chemical variables of the lagoons do not seem to be the cause of copepod ontogenic changes in AAC. Data suggest that AAC differences found between stages of copepod species could indicate a gradual change in diet during the life cycle of these copepods.     

Western Mediterranean immature loggerhead turtles: habitat use in spring and summer assessed through satellite tracking and aerial surveys

An aerial survey was conducted in early spring 2002 over the continental shelf of the Balearic Archipelago to study the distribution of neritic loggerhead turtles. Furthermore, five juvenile loggerhead turtles [straight carapace length (SCL) range 37.1–48.7 cm], were instrumented with transmitters and monitored during 2003 by satellite tracking to study habitat use over a broader geographical range. The distribution of the turtles over the continental shelf matched habitat availability, as defined by depth. However, those tracked by satellite spent most of the time in the oceanic waters of the Algerian basin and generally avoided continental shelf areas. In these turtles, average speed of travel and mean cosine of turning angle did not significantly differ between habitats, indicating that avoidance of shelf areas is not due to active habitat selection. On average, tracked turtles spent 35.1±19.7% of the time at the surface, although surface time was much greater in the turtle with the shortest carapace length, suggesting that this individual had limited swimming capacity. We conclude that the transition between passive drifting and active habitat selection occurs at an SCL of about 40 cm. The turtles followed tracks that matched prevailing currents, but on some occasions they also swam upstream. Hence, the distribution of late juvenile loggerhead turtles in the southern and central western Mediterranean may reflect a combination of passive drifting and active habitat selection.Communicated by O. Kinne, Oldendorf/Luhe     

Vision in the rufus snake eel,<Emphasis Type="Italic"> Ophichthus rufus</Emphasis>: adaptive mechanisms for a burrowing life-style

A unique retinal topography was found in the rufus snake eel, Ophichthus rufus, a burrowing fish that shows a preference for nocturnal habits. The cells in the ganglion-cell layer formed a high-density semicircular band that covered the dorso-rostral, temporal and ventro-rostral areas of the retina. Three regions of high acuity were identified in the ventro-temporal, ventro-rostral and dorsal regions of the retina. This is the first time that multiple specialisations have been found in a benthic deep-water fish. The ventro-temporal and ventro-rostral visual axes were found at 48° and 54° from the retinal centre, subtending the dorsal field of view, while the dorsal axis was at 66°, subtending the ventral field of view. These characteristics may represent an adaptation to identify the mouth of the muddy burrows in which this species hides or where it looks for food. O. rufus has a duplex retina with numerous slender rod photoreceptors arranged in banks of four layers. This morphology is typical of deep-sea teleosts with a high visual sensitivity, which is useful in a dim-light environment. A few tiny cones were also present, probably enhancing acuity during the eel's daily activity. The retina of O. rufus also possessed a well developed vascularisation, possibly to overcome the hypoxic conditions that may be found in the burrow. The characteristics of the retina of the rufus snake eel indicate singular visual capabilities that are discussed in relation to the burrowing life-style and to what is known of feeding habits of this fish.     

Mercury speciation in fluorescent lamps by thermal release analysis

In this work, mercury speciation in phosphorus powder matrices and soda lime glass waste from new and spent fluorescent lamp wastes has been studied by thermo-desorption/atomic absorption spectrometry (TDAAS), X-ray diffraction (XRD), cold vapor-atomic absorption (CV-AAS) and atomic emission spectrometry/inductively coupled plasma (ICP/AES). TDAAS results show the presence of oxidized forms of mercury, i.e., Hg(1+) and Hg(2+), especially in wastes with high mercury concentration. Such forms are mobile, and therefore represent a potential hazard waste material. Glass TD profiles of spent fluorescent lamps suggested the presence of mercury strongly linked to the matrix, which desorbs only at high temperatures.     

Potential nitrification and denitrification on different surfaces in a constructed treatment wetland

Improved understanding of the importance of different surfaces in supporting attached nitrifying and denitrifying bacteria is essential if we are to optimize the N removal capacity of treatment wetlands. The aim of this study was therefore to examine the nitrifying and denitrifying capacity of different surfaces in a constructed treatment wetland and to assess the relative importance of these surfaces for overall N removal in the wetland. Intact sediment cores, old pine and spruce twigs, shoots of Eurasian watermilfoil (Myriophyllum spicatum L.), and filamentous macro-algae were collected in July and November 1999 in two basins of the wetland system. One of the basins had been constructed on land that contained lots of wood debris, particularly twigs of coniferous trees. Potential nitrification was measured using the isotope-dilution technique, and potential denitrification was determined using the acetylene-inhibition technique in laboratory microcosm incubations. Nitrification rates were highest on the twigs. These rates were three and 100 times higher than in the sediment and on Eurasian watermilfoil, respectively. Potential denitrification rates were highest in the sediment. These rates were three times higher than on the twigs and 40 times higher than on Eurasian watermilfoil. The distribution of denitrifying bacteria was most likely due to the availability of organic material, with higher denitrification rates in the sediment than on surfaces in the water column. Our results indicate that denitrification, and particularly nitrification, in treatment wetlands could be significantly increased by addition of surfaces such as twigs.     

Assessment of plastic lumber production in Brazil as a substitute for natural wood

Environment, Development and Sustainability - This review aimed to analyze plastic lumber manufacturing in Brazil, a country with a large amount of natural wood, and devise strategies to boost...