Mercury loss from soils following conversion from forest to pasture in Rondônia, Western Amazon, Brazil

This work reports on the effect of land use change on Hg distribution in Amazon soils. It provides a comparison among Hg concentrations and distribution along soil profiles under different land use categories; primary tropical forest, slashed forest prior to burning, a 1-year silviculture plot planted after 4 years of forest removal and a 5-year-old pasture plot. Mercury concentrations were highest in deeper (60-80 cm) layers in all four plots. Forest soils showed the highest Hg concentrations, ranging from 128 ngg(-1) at the soil surface to 150 ngg(-1) at 60-80 cm of depth. Lower concentrations were found in pasture soils, ranging from 69 ngg(-1) at the topsoil to 135 ngg(-1) at 60-80 cm of depth. Slashed and silviculture soils showed intermediate concentrations. Differences among plots of different soil-use categories decreased with soil depth, being non-significant below 60 cm of depth. Mercury burdens were only statistically significantly different between pasture and forest soils at the topsoil, due to the large variability of concentrations. Consequently, estimated Hg losses were only significant between these two land use categories, and only for the surface layers. Estimated Hg loss due to forest conversion to pasture ranged from 8.5 mgm(-2) to 18.5 mgm(-2), for the first 20 cm of the soil profile. Mercury loss was comparable to loss rates estimated for other Amazon sites and seems to be directly related to Hg concentrations present in soils.     

The importance of crossroads in faecal marking behaviour of the wolves (<Emphasis Type="Italic">Canis lupus</Emphasis>)

For wolves (Canis lupus) scats play an important function in territorial marking behaviour. Depositing scats at strategic sites such as crossroads and on conspicuous substrates probably increases their effectiveness as visual and olfactory marks. It is therefore likely that scats will be deposited, and will accumulate, at particular crossroads where the probability of being detected by other wolves is greatest. To check this hypothesis, a wolf population in NW Spain was studied for two consecutive years, from May 1998 to March 2000, and the spatial distribution of 311 scats detected along roads (both at and away from crossroads) was analysed. This study was conducted over an area of 12,000 ha in Montes do Invernadeiro Natural Park. The results confirm that wolves preferably deposit their scats at crossroads (60.1%) and on conspicuous substrates (72.1%). Significantly more scats were found at intersections with numerous, easily passable roads connecting distant territories. Thus, wolves preferably deposit their faeces at crossroads with high accessibility and driveability. The larger the surface area of the crossroads, the more scats were found. Crossroads are therefore highly strategic points that facilitate the detection of scats.     

Correction to: Ecological restoration as a strategy for mitigating and adapting to climate change: lessons and challenges from Brazil

Mitigation and Adaptation Strategies for Global Change - The original version of the article unfortunately contained an error.     

New contributions to the study of common double mutants in the human <Emphasis Type="Italic">LDL</Emphasis> receptor gene

Variations in the gene encoding the low-density lipoprotein receptor (LDLR) can cause familial hypercholesterolemia (FH), one of the most common inherited metabolic disorders in humans. The functional effects of the p.Gln92Glu and p.Asn564His alterations are predicted as benign, but the c.313 + 1G>C and p.Lys799_Phe801del changes are believed to cause disease. Although p.Gln92Glu and c.313 + 1G>C have been observed only in Spain, p.Asn564His and p.Lys799_Phe801del are widespread in Western Europe. In order to estimate the ages (t generations) of these four variants of the gene, to determine their possible origin and to consider the influence of age and selective pressure on their spread, we analyzed 86 healthy individuals and 126 FH patients in Spain. Most of the FH patients investigated carried two of these four LDLR variants simultaneously, while only one patient carried three of them simultaneously. Haplotype analyses were based on five LDLR SNPs: c.81T>C, c.1413G>A, c.1725C>T, c.1959T>C and c.2232G>A. The results suggest that p.Gln92Glu and c.313 + 1G>C arose at about the same time (99 and 103 generations ago, respectively) in the CACTG haplotype and that p.Asn564His and p.Lys799_Phe801del appeared in the CGCCG haplotype and might be slightly more recent variations (92 and 95 generations ago, respectively). Low selective pressures could explain the maintenance of these variants in spite of their ages. The origin of p.Gln92Glu and c.313 + 1G>C appears to be in Spain whereas p.Asn564His and p.Lys799_Phe801del could have been introduced in Spain by Celtic migrations in the seventh to fifth centuries BC.     

Providing a common diet to different marine decapods does not standardize the fatty acid profiles of their larvae: a warning sign for experimentation using invertebrate larvae produced in captivity

Larval decapods are commonly produced in captivity and employed in experiments to evaluate interspecific physiological and biochemical differences. Currently, it is still unknown if different decapod species provided a common diet and exposed to identical abiotic conditions produce newly hatched larvae (NHL) with similar fatty acid (FA) profiles. This study analyzed the FA composition of NHL from five marine shrimp species (Lysmata amboinensis, L. boggessi, L. debelius, L. seticaudata and Rhynchocinetes durbanensis) fed a common diet and stocked at constant temperature. FA profiles of NHL differed significantly within and among genera. NHL from species unable to molt from zoea I to zoea II in the absence of food (L. amboinensis, L. debelius and R. durbanensis) displayed the lowest FA contents. Researchers must be aware that providing a common diet to different species, even if closely related, may not standardize the FA profile of NHL produced in captivity.     

Behavioural determinants of gene flow in the bat Miniopterus schreibersii

Dispersal and migratory behaviours are often important determinants of gene flow in wild species, and we have studied their role using ringing-recapture data in the Portuguese population of Miniopterus schreibersii, a cave-dwelling bat that forms large maternity colonies. Juvenile dispersal, usually a major agent of gene flow, appears to be negligible, as young females never settled to give birth in foreign colonies. Likewise, there was virtually no dispersal of adult females to foreign maternity colonies. This strong philopatry virtually eliminated female-mediated gene flow, but we found a great potential for male-mediated gene flow among colonies, as regional migrations temporarily joined both sexes from different colonies in the same roosts, during the mating season. In fact, females from some colonies were more likely to mate with males from foreign colonies than from their own, thus potentially bringing home genes of foreign males. In spite of this abundant gene flow, we found a pattern of isolation by distance and even strong barriers to gene flow, which is explained by the fact that migrations were usually too short to allow direct flow among distant colonies. We concluded that potential gene flow is influenced by the distance between colonies and the availability of mating roosts between them. In addition, we found this flow to be asymmetrical, with a dominant direction from the largest to the smallest colonies. Our ringing-recapture estimates of potential gene flow based on dispersal and migratory behaviour are compatible with the genetic structure of the population for both nuclear and mitochondrial DNA. Our conclusions have implications for the conservation of bats with a spatial behaviour similar to that of M. schreibersii. Colonies should be managed individually because strict female philopatry not only promotes their isolation but also minimises the contribution of immigration in rescuing declining colonies. Furthermore, the results underline the importance of preserving mating roosts to maintain gene flow among colonies.     

Basis for a national strategy for integrated coastal zone management—in Portugal

This paper includes the proposals made in the report “Basis for a National Strategy for Coastal Zone Management” prepared for the Portuguese Ministry of Environment, Territorial Planning and Regional Development. The final version of that report was presented in June 2006. This paper describes a theme framework followed by a discussion of concepts. Nine Primary Principles, eight Principal Objectives, and 37 Strategic Options for an Integrated Coastal Zone Management are then presented. These Strategic Options are set hierarchically according to their sequential priority, identifying the dominant types of Associated Measures. The analysis of these arrives at a set of Structural Measures, which interlink and aggregate various actions and propose a new method of integrated management for the coastal zone, which includes the “Legal Basis of Coastal Zone”; the Organization System; the Action Plan and Monitoring.     

Network analysis reveals contrasting effects of intraspecific competition on individual vs. population diets

Optimal foraging theory predicts that individuals should become more opportunistic when intraspecific competition is high and preferred resources are scarce. This density-dependent diet shift should result in increased diet breadth for individuals as they add previously unused prey to their repertoire. As a result, the niche breadth of the population as a whole should increase. In a recent study, R. Svanb?ck and D. I. Bolnick confirmed that intraspecific competition led to increased population diet breadth in threespine stickleback (Gasterosteus aculeatus). However, individual diet breadth did not expand as resource levels declined. Here, we present a new method based on complex network theory that moves beyond a simple measure of diet breadth, and we use the method to reexamine the stickleback experiment. This method reveals that the population as a whole added new types of prey as stickleback density was increased. However, whereas foraging theory predicts that niche expansion is achieved by individuals accepting new prey in addition to previously preferred prey, we found that a subset of individuals ceased to use their previously preferred prey, even though other members of their population continued to specialize on the original prey types. As a result, populations were subdivided into groups of ecologically similar individuals, with diet variation among groups reflecting phenotype-dependent changes in foraging behavior as prey density declined. These results are consistent with foraging theory if we assume that quantitative trait variation among consumers affects prey preferences, and if cognitive constraints prevent individuals from continuing to use their formerly preferred prey while adding new prey.     

Porous media approach for RANS simulation of compound open-channel flows with submerged vegetated floodplains

Environmental Fluid Mechanics - The main goal of this study is the 3D numerical simulation of river flows with submerged vegetated floodplains. Since, vegetation layers are usually dense and...     

Endocrine disruptors in the Leça River and nearby Porto Coast (NW Portugal): presence of estrogenic compounds and hypoxic conditions

The Leça River and two beaches close to the north and south margins of the estuary, nowadays an important seaport harbor, show signs of contamination. However, the chemical nature of that contamination is uncertain. Therefore, this study checked for the presence of 11 endocrine disrupting compounds (EDCs) of animal (17β-estradiol and estrone), pharmaceutical (17α-ethynylestradiol), and industrial (alkylphenols, alkylphenol ethoxylates, and bisphenol A) origins in water samples collected from six points at the river gradient and at two sites in the coastline (Atlantic Ocean). Along with the EDCs, evaluated by gas chromatography – mass spectroscopy (GC-MS) during spring, summer, and autumn, physico-chemical parameters were also assessed and particular attention was given to dissolved oxygen (DO) levels. Data showed the presence of high amounts of estrogens (up to 10?ng?L^?1 for estrone) and industrial compounds (up to 2?µg?L^?1 for the nonylphenol ethoxylates) at both river and seacoast. Along with this, clear signs of hypoxia were found in the river (DO??1 at several sampling sites). Taking into account these issues, it was concluded that there are local conditions for the occurrence of endocrine disruption in aquatic animals.