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561.
Veterinary drugs used in dairy production are potential contaminants of surface or groundwater sources, being able to affect human and environmental health. It is known that chronic exposure to antibiotics in low concentrations present in water can generate microbial resistance. This study aimed to evaluate the presence of veterinary drugs in 53 groundwater samples used for animal and human consumption, collected in dairy milking parlors, in an important milk-producing area of central Argentina, and to assess the risk to human health when they are used as drinking water. In 75% of the total samples analyzed, at least one veterinary drug was detected. The most frequently found drugs in water samples were the antibiotics tetracycline in 58.5% and oxytetracycline in 56.6%, and an anti-inflammatory, flunixin in 39.6%. In the water samples, the tetracycline and oxytetracycline concentrations were between 0.1 and 5.3 μg/L and flunixin concentrations were between 0.01 and 2.1 μg/L. The frequency of appearance and the concentration levels of the substances found in the water samples were evaluated according to the productivity, size, and production system (confined or pasture) of the dairy farms. Higher concentrations and proportions of water samples containing antibiotics were observed when the number of animals per dairy farm was >182 and when the productivity was high (>25 liters per animal per day). In the case of flunixin, the percentage of detection was similar in all evaluated categories. The risk assessment for children and adults, considering the intake of drinking water containing residues of these drugs, did not indicate a significant health risk. It would be advisable to evaluate other sources of drinking water, both surface and underground, in other regions of the country, to provide data to assess the impact of these substances and the other contaminants on environmental and human health.  相似文献   
562.
The conservation of long-distance migratory birds requires coordination between the multiple countries connected by the movements of these species. The recent expansion of tracking studies is shedding new light on these movements, but much of this information is fragmented and inaccessible to conservation practitioners and policy makers. We synthesized current knowledge on the connectivity established between countries by landbirds and raptors migrating along the African–Eurasian flyway. We reviewed tracking studies to compile migration records for 1229 individual birds, from which we derived 544 migratory links, each link corresponding to a species’ connection between a breeding country in Europe and a nonbreeding country in sub-Saharan Africa. We used these migratory links to analyze trends in knowledge over time and spatial patterns of connectivity per country (across species), per species (across countries), and at the flyway scale (across all countries and all species). The number of tracking studies available increased steadily since 2010 (particularly for landbirds), but the coverage of existing tracking data was highly incomplete. An average of 7.5% of migratory landbird species and 14.6% of raptor species were tracked per country. More data existed from central and western European countries, and it was biased toward larger bodied species. We provide species- and country-level syntheses of the migratory links we identified from the reviewed studies, involving 123 populations of 43 species, migrating between 28 European and 43 African countries. Several countries (e.g., Spain, Poland, Ethiopia, Democratic Republic of Congo) are strategic priorities for future tracking studies to complement existing data, particularly on landbirds. Despite the limitations in existing tracking data, our data and results can inform discussions under 2 key policy instruments at the flyway scale: the African–Eurasian Migratory Landbirds Action Plan and the Memorandum of Understanding on the Conservation of Migratory Birds of Prey in Africa and Eurasia.  相似文献   
563.
Male intrasexual competition and female choice explain the evolution of male ornaments. Except in sex-role-reversed taxa, female ornaments have been regarded as an epiphenomenon of genetic correlation, with no female-specific function or independently selected basis. Females from species with conventional sex roles may still experience some degree of female–female competition and male choice that could explain the persistence of female ornaments. We studied the effect of female competition on the expression of a sexually dimorphic communication signal. In the electric fish Brachyhypopomus gauderio, both sexes produce an electric signal pulse for communication and electrolocation. Male electric pulses are longer in duration and greater in amplitude than those of females. As competition increases, males further enhance their signals in response to elevated androgen levels. We explored whether females respond to social competition as males do, by enhancing their communication signals and increasing androgen levels. We measured amplitude and duration of the electric signal pulse, and testosterone levels in female B. gauderio in their natural habitat in Uruguay and estimated social competition by calculating population density and adult sex ratio (ASR). In the lab, we manipulated ASR and population density independently to separate these factors and eliminate seasonal confounds. Under both field and lab conditions, signal pulse amplitude increased with population density, while pulse duration increased with female bias in ASR. In the field, but not the lab, androgen levels increased when ASR was female biased. Our findings indicate that the socially mediated mechanism of signal regulation is shared by the sexes, although whether androgens regulate this signal plasticity in females remains unclear.  相似文献   
564.
We report current genetic variation of populations of the razor shell Ensis directus (Conrad 1843) (Mollusca: Bivalvia: Pharidae) in native (North American) and introduced (European) ranges using nuclear and mitochondrial sequence-based markers. We expected less variation within the introduced range, especially considering the frequent mass mortality events observed in Europe since the species was recorded for the first time in 1978. However, we found higher variation in Europe. The possible significance of temporal fluctuations of genetic variation, limited effect of random genetic drift, and multiple introductions are discussed. Interestingly, the multiple-introduction hypothesis contrasts with the gradual colonisation of European coastal waters but is supported by trained clustering analysis and by the intensity of transatlantic shipping. Genetic and morphometric evidence strongly supports that examined individuals from a supposed E. directus population from Newfoundland (Canada) belong to a separate species. This new Ensis is formally described here and named E. terranovensis n.sp.  相似文献   
565.
Kelp gulls (Larus dominicanus) feed on pieces of skin and blubber they rip from Southern right whales’ (Eubalaena australis) backs in their breeding areas at Península Valdés, Argentina, producing injuries. This behavior has increased since the first record in 1972, and some authors have suggested that constant gull harassment could have a negative effect on right whale population. The main goal of this study is to assess the variables that most affect the gull attacks. We analyzed 5359 whale-watching sightings made during trips from Puerto Pirámides (42o34′S, 64o16′W) along the whale breeding seasons (June–December) 2005 to 2007. The most important factors affecting the attacks include the presence of a mother–calf pair, the time within the season, the distance to the coast and the wind velocity. There is also concern of possible transmission of infectious diseases in the attacks since increasing number of whales with different patterns of skin lesions have been observed.  相似文献   
566.
The bottlenose dolphin (Tursiops truncatus) is the most common cetacean species worldwide and the only marine mammal species resident in the Croatian part of the Adriatic Sea. To gain insight into genetic diversity of bottlenose dolphins at adaptively important loci relevant to conservation, we analysed the polymorphism of major histocompatibility complex (MHC) genes, which play a key role in pathogen confrontation and clearance. Specifically, we examined the diversity of MHC class II DRA, DQA and DQB alleles in 50 bottlenose dolphins from the Adriatic Sea collected between 1997 and 2011 and in 12 animals from other Mediterranean locations. Notable variation in DQA, DQB and three-locus haplotypes was found, with all 10 DQA and 12 DQB alleles encoding unique protein products. Analysis of the ratio of non-synonymous to synonymous substitution rates suggests that positive selection acts at both highly variable loci. Phylogenetic analyses revealed trans-species polymorphism at the DQB locus, strongly indicating the influence of balancing selection in the long term. In fact, the balancing selection observed in bottlenose dolphins is higher than that reported for most other cetaceans and comparable to that seen in terrestrial mammals.  相似文献   
567.
Trace metal concentrations were determined in particulate matter (PM10) in ambient air of four purposively selected residential areas in Ibadan, Nigeria namely Bodija market (BM), Ojo Park (OP), Oluyole Estate (OE) and University of Ibadan (UI). PM10 was determined in the morning (7–10 a.m.) and afternoon (2–5 p.m.) for 12 weeks in the dry season months of January–March using a volumetric sampler following standard procedures and levels compared with WHO guideline limits. Glass-fibre filter papers exposed to the particulate matter were digested using appropriate acid mixtures, and the digest analysed for trace metals including Ni, Cr, Mn, Zn, and Pb using ICPMS method and levels compared with WHO limits. Data was analysed using ANOVA and Pearson correlation test at 5 % level of significance. The highest mean PM10 concentrations 502.3 ± 39.9 μg/m3 were recorded in the afternoon period at BM, while the lowest concentration 220.6 ± 69.9 μg/m3 was observed in the morning hours at UI. There was a significant difference between the PM10 levels across the various locations (p < 0.05), and all the levels were higher than WHO limit of 50 μg/m3. The highest levels of Ni, Zn and Pb were recorded at BM, which also had the highest PM10 burden. The trend in Pb levels across the locations was BM > UI > OP > OE with the highest level 5.70 μg/m3 in BM nearly fourfolds WHO limits of 1.5 μg/m3. There was a significant correlation between PM10 and Ni (p < 0.05).Urban communities with increased human activities especially motor traffic recorded both higher levels of PM10 and toxic trace metals. There is need to carry out source apportionment to establish the origin of these trace metals in future studies.  相似文献   
568.
This introduction article is for the special issue ‘Managing organizations for sustainable development in emerging countries: natural resources, biodiversity, and climate change’ in the International Journal of Sustainable Development & World Ecology and presents an introduction to the topics and summarizes accepted contributions in the special issue. The accepted works may contribute with organizational management in the search for more sustainable organizations. The works focus on the challenges of managing organizations in a context of degradation of natural resources, loss of biodiversity, and climate change. Accepted papers discuss these issues, based on the reality of emerging economies (e.g. Brazil, India, and China).  相似文献   
569.
The new properties of engineered nanoparticles drive the need for new knowledge on the safety, fate, behavior and biologic effects of these particles on organisms and ecosystems. Titanium dioxide nanoparticles have been used extensively for a wide range of applications, e.g, self-cleaning surface coatings, solar cells, water treatment agents, topical sunscreens. Within this scenario increased environmental exposure can be expected but data on the ecotoxicological evaluation of nanoparticles are still scarce. The main purpose of this work was the evaluation of effects of TiO2 nanoparticles in several organisms, covering different trophic levels, using a battery of aquatic assays. Using fish as a vertebrate model organism tissue histological and ultrastructural observations and the stress enzyme activity were also studied. TiO2 nanoparticles (Aeroxide® P25), two phase composition of anatase (65%) and rutile (35%) with an average particle size value of 27.6±11 nm were used. Results on the EC50 for the tested aquatic organisms showed toxicity for the bacteria, the algae and the crustacean, being the algae the most sensitive tested organism. The aquatic plant Lemna minor showed no effect on growth. The fish Carassius auratus showed no effect on a 21 day survival test, though at a biochemical level the cytosolic Glutathione-S-Transferase total activity, in intestines, showed a general significant decrease (p<0.05) after 14 days of exposure for all tested concentrations. The presence of TiO2 nanoparticles aggregates were observed in the intestine lumen but their internalization by intestine cells could not be confirmed.  相似文献   
570.
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.  相似文献   
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