Acoustic communities in an environmental gradient from native to urban areas in Central Brazil

As urban areas expand due to increasing human populations, natural habitats are diminishing in quantity and quality. We conducted a study to examine the response of diurnal acoustic communities along a gradient of environments, ranging from native to dense urban areas. We hypothesized that acoustic indices would decline with urbanization, transitioning from natural and rural areas to urban environments. We conducted the research in and around Brasília, Central Brazil. We deployed 24 digital recorders in native, rural, low-density and high-density urban areas. We employed five commonly used acoustic indices (ADI, ACI, NDSI, H and BI) to characterize the acoustic communities and represent the existing biodiversity numerically. We initially compared the index values across different land use types using a non-parametric rank sum test. Subsequently, we selected eight landscape metrics and performed a principal component analysis to summarize the surrounding matrix at each sampling point. We then employed generalized linear models to determine if the acoustic indices exhibited the anticipated variations. The results indicated significant variations in all indices among the different land use types, indicating their responsiveness to distinct acoustic communities and environmental characteristics. ADI, H and NDSI exhibited declining values from native to urban areas, while ACI and BI displayed the opposite trend. These findings underscore the influence of landscape structure on acoustic indices. Consequently, we concluded that adopting appropriate landscape planning, mainly through integrating natural and urban areas, could help preserve biodiversity in tropical urban regions.     

Environmental influences on local amphibian diversity: the role of floods on river basins

We tested two hypotheses about boundary units and seven about environmental control of species diversity in order to explain geographical trends in the richness of amphibian species in the Mediterranean watershed of the southern coast of the Iberian Peninsula. The number of amphibian species tends to decrease from west to east. The longitudinal trend in the richness of amphibian species actually occurs on passing from one basin to another, but there is not any longitudinal trend within the basins. Multivariate analyses confirmed that the disturbances of episodic river-basin floodings were the principal factor which controls the richness of amphibian species. They explained 94.8% of the observed variations in the richness of amphibian species in this area, according to the intermediate disturbance hypothesis.We propose hydrographic basins as suitable geographical units for further biogeographical analysis and for considering the role of disturbances produced by floods in the environmental control of species diversity.     

Trophic ecology of juvenile bull sharks (Carcharhinus leucas) in the Coyote estuary,Costa Rica

Bull shark (Carcharhinus leucas) is a near-threatened elasmobranch species capable of moving between the fresh and salty waters of tropical and subtropical coastal areas, for which we still lack important ecological information. During their first years of life, bull sharks use estuarine systems as nursery areas, making them highly susceptible to environmental and anthropogenic pressures. We studied the trophic ecology of juveniles found in the Coyote estuary, a potential nursery area in Costa Rica, to understand the potential impact of further bull shark declines and gain knowledge that could aid in their conservation. We analysed the trophic ecology of juvenile bull sharks [81–103 cm total length (TL)] in the Coyote estuary, Costa Rica, using stable isotopes of δ¹⁵N and δ¹³C. Since one problem using this technique in juveniles is the confounding effect of the maternal signature, we sampled different tissues (muscle and plasma), verified the status of the shark's umbilical scar and identified the size at which the isotope signature is a result of the animal's current diet. The isotopic values of the muscle tissue reflected the maternal isotopic signature. In contrast, plasma values reflected the diet of juvenile bull sharks >95 cm TL and with a closed umbilical scar. Juvenile bull sharks fed primarily on teleost fishes of the order Anguilliformes and Siluriformes, and have a high trophic position (≥4.0) in the Coyote estuary. Our findings suggest that this estuary is an important feeding site for juvenile bull sharks of the Pacific of Costa Rica. Thus, the protection of essential habitats such as the Coyote estuary will benefit not only bull shark conservation, but also the conservation of an array of fish species that also use this habitat as a rookery, many of which are of commercial interest.     

Casearia Essential Oil: An Updated Review on the Chemistry and Pharmacological Activities

Casearia species are found in the America, Africa, Asia, and Australia and present pharmacological activities, besides their traditional uses. Here, we reviewed the chemical composition, content, pharmacological activities, and toxicity of the essential oils (EOs) from Casearia species. The EO physical parameters and leaf botanical characteristics were also described. The bioactivities of the EOs from the leaves and their components include cytotoxicity, anti-inflammatory, antiulcer, antimicrobial, antidiabetic, antioxidant, antifungal, and antiviral activities. The main components associated with these activities are the α-zingiberene, (E)-caryophyllene, germacrene D, bicyclogermacrene, spathulenol, α-humulene, β-acoradiene, and δ-cadinene. Data on the toxicity of these EOs are scarce in the literature. Casearia sylvestris Sw. is the most studied species, presenting more significant pharmacological potential. The chemical variability of EOs components was also investigated for this species. Caseria EOs have relevant pharmacological potential and must be further investigated and exploited.     

A biphasic model of limb venous compliance: a comparison with linear and exponential models.

Compliance is not linear within the physiological range of pressures, and linear modeling may not describe venous physiology adequately. Forearm and calf venous compliance were assessed in nine subjects. Venous compliance was modeled by using a biphasic model with high- and low-pressure linear phases separated by a breakpoint. This model was compared with a linear model and several exponential models. The biphasic, linear, and two-parameter exponential models best represented the data. The mean coefficient of determination for the biphasic model was greater than for the linear and exponential models in the calf (biphasic 0.94 +/- 0.04, exponential 0.81 +/- 0.16, P = not significant; and linear 0.54 +/- 0.05, P < 0.05) and forearm (biphasic 0.83 +/- 0.17, exponential 0.79 +/- 0.15, P = not significant; and linear 0.51 +/- 0.06, P < 0.05). The breakpoint pressure in the biphasic model was higher in the calf than the forearm, 34.4 +/- 3.9 vs. 29.1 +/- 4.5 mmHg, P < 0.05. A biphasic model can describe limb venous compliance and delineate differences in venous physiology at high and low pressures. The steep low-pressure phase of the compliance curve extends to higher pressures in the calf than in the forearm, thereby enlarging the range of pressures over which hemodynamic regulation by the calf venous circulation occurs.