Mineral and essential element measurements in dolphin bones using two analytical approaches

We explored the potential of using energy-dispersive X-ray analysis (EDX), a non-destructive technique, to assess elemental contents in dolphin bones. Specimens were deposited in museum collections, and prepared by different methodologies. Fifty eight Commerson’s dolphins (Cephalorhynchus c. commersonii) chevron bones and 24 Franciscana dolphins (Pontoporia blainvillei) were analysed. The EDX allowed us to detect the following elements: Ca, P, Na, Mg, Fe, K, Zn, S, Cl and Al; and quantify their proportion (weight percent of element). Principal components analysis differentiates two groups according to the cleaning procedures applied, supporting that cleaning methods could influence the chemical integrity of bone. No significant age-dependent increase was found for elements analysed in species, and no significant differences were found between sex and physical maturity stages. Alternative assessment was made through atomic absorption spectrophotometry, providing quantitative information on the principal elements in bones (Ca, P, Mg, Na, Fe and Zn) and allowing comparisons with other studies. A standard protocol for bone cleaning and conditioning is needed to exclude any effect on the mineral integrity of calcified tissue. This would enable future comparative studies on the bone mineral matrix over time housed in natural history museums or other scientific collections.     

Sperm polymorphism and genetic divergence in the mussel Perumytilus purpuratus

For the first time in a marine bivalve species, geographic intraspecific variation in sperm morphology in the Chilean mussel, Perumytilus purpuratus, is reported. Samples were obtained in December 2010 from the rocky intertidal at three locations: Antofagasta (23o44′01.08′′S, 70o26′26.11′′W), Valparaíso (32o57′23.07′′S, 71o33′01.86′′W), and Valdivia (39°50′44.26′′S, 73°25′51.99′′W). Scanning electron microscopy was used to describe sperm traits, and genetic data were obtained by sequencing a 16S mtDNA 427-bp fragment. The results showed geographic intraspecific variation with two statistically significant patterns of genetically differentiated sperm morphologies. One genetic clade was found for Antofagasta and Valparaíso, displaying a unique sperm morphotype with a short acrosome accounting for 26 % of the head length, and the other from Valdivia, with a larger acrosome occupying 47 % of the head length. These results will lead to new research to distinguish among alternative hypotheses: the presence of cryptic species, incipient speciation, or a polymorphism in sperm traits of P. purpuratus.     

Post-dispersal predation of weed seeds by small vertebrates: Interactive influences of neighbor land use and local environment

The influences of spatial scale, local conditions, and small vertebrate preferences on post-dispersal predation of weed seeds were tested in agricultural ecosystems of the Southern Pampas Region of Argentina. Seeds from different weed species were offered through exclusion experiments at different distances from the weedy field borders, inside maize (2005) and wheat (2006) stubbles with contrasting land use in the neighbor fields (annual crop fields vs. seminatural grasslands), and inside seminatural grasslands adjacent to stubbles. Canopy structure was characterized inside the wheat stubbles, and small mammals were sampled in both stubble crops and grasslands. All weed species were predated in both 2005 and 2006 trials, but predation ratios varied among weed species, partly due to their seed size, with larger ones being more preferred. While in the maize stubbles no distance or neighbor field land use effects, or interactions between the different factors were detected, in the wheat stubbles, influence of neighbor field land use on weed species predation varied according to distance from field border and the height of the stubble canopy. In wheat stubbles adjacent to annual crop fields, predation increased with canopy height at every different distance from the field borders (5 m, 30 m and 60 m). The opposite was found in wheat stubbles adjacent to seminatural grasslands, where seed predation sharply decreased with canopy height, except for the farthest distance to the border. Capture results suggest a predominance of Calomys spp. populations in crop areas (stubbles adjacent to annual crops) which contrasted with the more diverse small mammal’s community of the grasslands. Based on these data, we provide an insight into the hierarchical nature of factors affecting the predation of weed seeds and discuss some implications of land use patterns on the regulation of weed populations by small vertebrates.     

Reducing visitors' group size increases the number of birds during educational activities: Implications for management of nature-based recreation

Organized tours to watch wildlife are popular recreational and educational activities, in which the visitor expectative (to observe as many and as diverse animals as possible) runs parallel to conservation purposes. However, the presence of visitors may cause negative impacts on wildlife, which makes recreation difficult to manage. Thus, restricting visitor's load to minimize impacts on fauna may be advisable, but too much restriction may end up disappointing the public. We analysed how visitors' group size influences the number and variety of birds observed during an educational activity directed to scholars, in a forested area where public access is otherwise restricted. We observed fewer birds, but not fewer species, as the size of scholars' groups increased. Such effect was apparently mediated by a few species demonstrating reduced tolerance to increased group size. Our results support the idea that reducing the size of visitors' groups not only helps to minimize the negative impacts on wildlife derived from leisure activities, but also allows visitors to watch more wildlife. Therefore, organizing visitors in small numbers is recommended in the design of activities directed to groups of people visiting natural areas.     

Lead exposure and its association with neurological damage: systematic review and meta-analysis

Environmental Science and Pollution Research - Lead (Pb) is one of the most toxic and abundant elements in the earth’s crust, which is pointed out that the intoxication caused by it...     

Phytotoxicity,cytotoxicity, and in vivo antifungal efficacy of chitosan nanobiocomposites on prokaryotic and eukaryotic cells

Environmental Science and Pollution Research - Chitosan (CS) nanosystems have potential applications for the control of microorganisms in the medical, environmental, and agrifood fields. In vivo...     

Enhancing the visible-light photoactivity of silica-supported TiO2 for the photocatalytic treatment of pharmaceuticals in water

Environmental Science and Pollution Research - Catalyst samples based on SiO2-supported TiO2 were prepared with the incorporation of Ag (metal), S (nonmetal), and ZnO@S (semiconductor and...     

Substitution of urea–formaldehyde by renewable phenolic compound for environmentally appropriate production of particleboards

Environmental Science and Pollution Research - In recent years, research has been conducted in search of alternative adhesives that are less harmful to human health and the environment. Cardanol...