Functional and morphological alterations induced by uranyl nitrate in rat submandibular gland

Exposure to uranium (U) is an occupational hazard to workers who continually handle it and an environmental risk to the population at large. Adverse effects of U on different tissues, particularly kidneys, have been reported. The aim of the present study was to investigate whether U might produce damage to the rat submandibular gland (SMG). Uranyl nitrate (UN) was used to evaluate the secretory responses to norepinephrine (NE) or to the parasympathomimetic agent, methacholine (MC), along with some morphological and histological parameters. In addition, the presence of U in saliva was determined by atomic absorption spectrometric techniques. Results indicate that intraperitoneal (i.p.) injection of a single dose of UN (2 or 4 mg kg^?1) induced a functional decrease in the induced secretory responses in the rat SMG, demonstrating for the first time that U interferes with salivary secretion. Moreover, salivary responses to MC as well as to NE were decreased after UN administration, in time- and dose-dependent manner, displaying a higher diminution after 7 days post injection. In agreement with the functional studies, the injection of UN produced morphological alterations of SMG, consisting in a reduction of mean acinar area and a marked vacuolization. Data indicate that UN produced an adverse effect in a dose- and time-dependent manner on SMG function and morphology. Furthermore, it was shown that U was incorporated in saliva and therefore, these findings may contribute to create a useful, noninvasive method to detect the exposure to U.     

Acute toxicity of roundup to the nontarget organism Hyalella curvispina. Laboratory and field study

Glyphosate is the most used pesticide in Argentina. Hyalella curvispina is a widely distributed and commonly abundant component of the invertebrate assemblages in shallow waters of southern South America. The aim of this study was to assess the acute toxicity of the increasingly common Roundup Full II®, commercial formulation of the herbicide glyphosate (66.2% active ingredient), to H. curvispina in laboratory and field assessments. The mean estimated 48-h LC₅₀ of Roundup was 9.9 ± 1.7 mg L^?1. In a field experiment Roundup was applied to soybean plots. Simulated rain was generated the following day by means of irrigation sprinkler equipment. H. curvispina was exposed to runoff water and soy leaves. No mortality was observed. It is suggested that Roundup crop applications represent a low risk of acute toxicity to H. curvispina adults inhabiting water bodies adjacent to crop fields.     

Indigenous people and sustainable development in Amazonas

Indigenous populations have lived for many generations in a sustainable fashion, developing knowledge about how to live in harmony with the environment. However, the sustainability of their life styles, their quality of life and the maintenance of intact ecosystems are threatened by a series of changes, including incorporation into the general fabric of society, conflict with non-indigenous migrants, expansion of indigenous populations and the globalization of national economies. This paper looks at the potential for policy to deal with these issues. In particular, it is shown that the ‘polluter pays principle’ is not appropriate for indigenous societies. The paper recommends a set of policies and shows how international cooperation in the areas of monitoring and enforcement, augmentation of demand for rain forest products and eco-certification can help indigenous groups improve their quality of life and maintain ecosystems in their current undisturbed state.     

Bacterial Degradation of Vegetable Oils

Following initial experiments presented elsewhere (2IOPS), the bacterial degradation of two vegetable oils was investigated in some detail. the number of aerobic and anaerobic heterotrophic bacteria, oil degrading and sulphate reducing bacteria were quantified during simulated spills on a salt marsh. the sediment fatty acid composition was also studied using GC-MS analysis. Degradation of linseed and sunflower oils was concomitant with an increase in the numbers of aerobic and anaerobic bacteria. Fatty acids analysis revealed preferential degradation of the principal components of the oils (18:3ω3 for linseed oil and 18:2ω6 for sunflower oil). the presence of several isomers of the usual polyunsaturated fatty acids was also detected. the identification of some of these new fatty acids has been carried out. Possible pathways of degradation of these vegetable oils are suggested.     

Breakwater control system and structural analysis: physical and numerical modelling (Port of Funchal,Madeira Island,Portugal)

The objective of this work was to analyze the behavior of the Funchal Port (Madeira Island, Portugal) breakwater using physical and numerical models in order to analyze the evolution of the underwater layers, combining information between the two models as well as simulating storm conditions and atypical docking/undocking impacts of cruise ships. Regarding the physical model using a wave generation system, the data collected and the test conditions were addressed considering different scenarios (return periods of 20, 50 and 100 years). It was found that for return periods of 20 years, the behavior of the infrastructure as a whole was stable. For return periods of 50 years, wave overtopping became more frequent and intense, and began to impact the superstructure. For the 100-year return period the behavior of the infrastructure was found to be unstable, with persistent wave overtopping. The morphology of the submerged layers also changed. The main objectives of the numerical model approach were to estimate the natural frequencies of vibration (when materials suffer a considerable modification, a change in their frequencies of vibration can be detected), and to calculate the expected displacements corresponding to cruise ship docking processes (agitation in a protected area) and the associated maximum maritime (agitation in an exposed area) forces. The maximum displacements obtained for the two cases were about 0.03 m, which is a high value. Considering the results obtained from this work, the Port authorities decided to maintain the monitoring program and perform an underwater video inspection.     

Explaining the fragmentation in the Brazilian Amazonian forest

Although vast literature exists on the drivers of tropical deforestation and its ecological consequences, less is known about how patterns of forest fragmentation emerge in the first place. The purpose of this paper is to address this issue for the Brazilian portion of the Amazon basin by analyzing the social processes generative of five specific patterns, including rectangular, fishbone, radial, dendritic, and what we refer to as ‘the stem of the rose.’ We argue that forest fragmentation patterns in the Brazilian Amazon are largely determined by the types and arrival times of the agents who engage in land clearing. We also argue that the patterns manifest in the landscape by virtue of road construction and agricultural property formation, which often occur in tandem. We conclude by placing our discussion within legal and institutional contexts, and observe that fragmentation stemming from formal colonization projects is more consistent with biodiversity conservation than that associated with a laissez-faire occupation. However, erosive impacts may be greater in topographically sensitive areas.     

Stressed, but not defenceless: no obvious influence of irradiation levels on antifeeding and antifouling defences of tropical macroalgae

The production of defence metabolites is assumed to be costly in metabolic terms. If this holds true, low-light stress should reduce the ability of seaweeds to defend themselves chemically against herbivory and fouling. We investigated the effect of energy limitation on the defensive status of seaweeds by assessing their attractiveness to mesograzers and their activity against a bivalve macrofouler in comparison with non-stressed conspecifics. The macroalgae Codium decorticatum (Woodw.) M. Howe, Osmundaria obtusiloba (C. Agardh) R. E. Norris, Pterocladiella capillacea (S. G. Gmel.) Santel. and Hommer., Sargassum vulgare C. Agardh and Stypopodium zonale (Lamour.) Papenf. collected at the southeastern Brazilian coast were exposed to six levels of irradiation (between 1 and 180 μmol photons m⁻² s⁻¹) for 10–14 days. After this period, algae from all treatment levels were: (a) processed as artificial food and offered to an amphipod community dominated by Elasmopus brasiliensis Dana and (b) extracted to test for differences in settlement rates of the fouling mussel Perna perna L. on filter paper loaded with the crude extracts. Generally, photosynthesis rates and growth were reduced under low light conditions. Attractiveness to herbivores and macrofoulers, however, was insensitive to energy limitation. We discuss possible explanations for the observed absence of a relationship between light availability and algal defence including the change in nutritional value of the algal tissue, the allocation of resources towards defence instead of growth and the absence of costs for defence.     

Long-term changes in phytoplankton phenology and community structure in the Bahía Blanca Estuary, Argentina

The phytoplankton of the Bahía Blanca Estuary, Argentina, has been surveyed since 1978. Chlorophyll a, phytoplankton abundance, species composition and physico-chemical variables have been fortnightly recorded. From 1978 to 2002, a single winter–early spring diatom bloom has dominated the main pattern of phytoplankton interannual variability. Such pattern showed noticeable changes since 2006: the absence of the typical winter bloom and changes in phenology, together with the replacement of the dominant blooming species, i.e. Thalassiosira curviseriata, and the appearance of different blooming species, i.e. Cyclotella sp. and Thalassiosira minima. The new pattern showed relatively short-lived diatom blooms that spread throughout the year. In addition, shifts in the phytoplankton size structure toward small-sized diatoms, including the replacement of relatively large Thalassiosira spp. by small Cyclotella species and Chaetoceros species have been noticed. The changes in the phenology and composition of the phytoplankton are mainly attributed to warmer winters and the extremely dry weather conditions evidenced in recent years in the Bahía Blanca area. Changing climate has modified the hydrological features in the inner part of the estuary (i.e. higher temperatures and salinities) and potentially triggered the reorganization of the phytoplankton community. This long-term study provides evidence on species-specific and structural changes at the bottom of the pelagic food web likely related to the recent hydroclimatic conditions in a temperature estuary of the southwestern Atlantic.     

Effects of seagrasses and algae of the Caulerpa family on hydrodynamics and particle-trapping rates

The widespread decline of seagrass beds within the Mediterranean often results in the replacement of seagrasses by opportunistic green algae of the Caulerpa family. Because Caulerpa beds have a different height, stiffness and density compared to seagrasses, these changes in habitat type modify the interaction of the seafloor with hydrodynamics, influencing key processes such as sediment resuspension and particle trapping. Here, we compare the effects on hydrodynamics and particle trapping of Caulerpa taxifolia, C. racemosa, and C. prolifera with the Mediterranean seagrasses Cymodocea nodosa and Posidonia oceanica. All macrophyte canopies reduced near-bed volumetric flow rates compared to bare sediment, vertical profiles of turbulent kinetic energy revealed peak values around the top of the canopies, and maximum values of Reynolds stress increased by a factor of between 1.4 (C. nodosa) and 324.1 (P. oceanica) when vegetation was present. All canopies enhanced particle retention rates compared to bare sediment. The experimental C. prolifera canopy was the most effective at particle retention (m² habitat); however, C. racemosa had the largest particle retention capacity per structure surface area. Hence, in terms of enhancing particle trapping and reducing hydrodynamic forces at the sediment surface, Caulerpa beds provided a similar or enhanced function compared to P.oceanica and C. nodosa. However, strong seasonality in the leaf area index of C. racemosa and C. taxifolia within the Mediterranean, combined with a weak rhizome structure, suggests that sediments maybe unprotected during winter storms, when most erosion occurs. Hence, replacement of seagrass beds with Caulerpa is likely to have a major influence on annual sediment dynamics at ecosystem scales.