Ocean surface winds drive local-scale movements within long-distance migrations of seabirds

Long-distance migration is a major part of the life cycle of many seabirds. The main processes driving local movements within those long-distance migratory movements are essentially unknown. Here, we studied detailed patterns of the movements with respect to distance from land of the most abundant seabird species migrating across the northernmost part of the Strait of Gibraltar and analysed how ocean surface winds influence those patterns. We did this by using visual and S-band radar surveys. Our results show that seabirds followed lines of travel that were located nearer the coast than randomly expected. Re-sampling techniques and comparison with additional data from ship-based counts corroborated this pattern, which was not substantially affected by the decrease in detection at distances of up to 3,000 m. Wind direction and speed covaried with local patterns of flight trajectories in a general manner. All the seabirds responded to headwinds by approaching the coast in proportion to the magnitude of wind intensity. Such a change in flight patterns could be a strategy to reduce the effect of headwinds, by approaching the coast where wind intensity was reduced by orographic factors. Under tailwind conditions, seabirds tended to fly further from the coast, profiting from increasing winds further from shore. Our results imply that modification of off-shore distance in relation to conditions of ocean surface winds may be an energetically advantageous strategy for migrating seabirds. Off-shore distances were also dependent on global and local migratory behaviour of different species, but not on flight type.     

Integrated survey of water pollution in the Suquía River basin (Córdoba, Argentina)

We report a combined two-year seasonal monitoring of Suquía River basin using both chemical parameters and biomarkers measured in Jenynsia multidentata, aiming to correlate external levels of contaminants with the response of oxidative stress biomarkers in this fish. Identified pollution sources correspond to city sewage as well as agricultural and small industry activities downstream from Córdoba city. Physicochemical parameters integrated into a water quality index (WQI) were measured in Suquía River during dry and wet seasons. Ag, Mn, Cu, Cr, Ni, Fe, Pb and Zn were also monitored in water and sediment samples. Biomarkers include detoxication and antioxidant enzymes: catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST) and glutathione reductase (GR). Enzymes showed a pollution dependent response, with increased activities in fish collected close to the sewage exit and progressive drop further downstream, matching changes in the Water Quality index. The combined use of biomarkers with water quality parameters allowed both the identification of pollution sources and the evaluation of effects of contaminants on the aquatic biota.     

Coastal lagoons: “transitional ecosystems” between transitional and coastal waters

The European Water Framework Directive (WFD) establishes a well differentiated typology of water bodies on the basis of scientific and biological criteria. For coastal waters, such criteria have long been established, while for transitional waters they are still under discussion. One of the difficulties when applying the WFD to coastal lagoons is to include them in only one of these categories, and while there is no doubt about the nature of estuaries as transitional waters, there is some controversy concerning lagoons. To what extent, reference conditions may be similar for estuaries and lagoons, or whether features common to all coastal lagoons are more important for differentiating them from other water bodies than the fact that there is (or is not) any fresh water influence, is something that remains unclear and is discussed in this work. Coastal lagoons and estuaries form part of a continuum between continental and marine aquatic ecosystems. Shelter, strong boundaries or gradients with adjacent ecosystems, anomalies in salinity regarding freshwater or marine ecosystems, shallowness, etc. all contribute to the high biological productivity of estuaries and lagoons and determine common ecological guilds in the species inhabiting them. On the other hand, fresh water influence, the spatial organization of gradients and environmental variability (longitudinal one-dimensional gradients in estuaries versus complex patterns and three-dimensional heterogeneity in lagoons) constitute the main differences, since these factors affect both the species composition and the dominance of certain ecological guilds and, probably, the system’s complexity and homeostatic capability. In the context of the WFD, coastal lagoons and estuaries are closer to each other than they are to continental or marine waters, and, on the basis of the shared features, they could be intercalibrated and managed together. However, coastal lagoons cannot be considered transitional waters according to the present definition. To assume that fresh water influence is an inherent characteristic to these ecosystems could lead to important changes in the ecological organization and functioning of coastal lagoons where natural fresh water input is low or null. In our opinion, the present day definition of transitional waters should be changed substituting the criterion of fresh water influence by another based on common features, such as relative isolation and anomalies in salinity in water bodies with marine influence. Otherwise, coastal lagoons should be considered a particularly characteristic type of water mass for establishing reference conditions of ecological status.     

House sparrows selectively eject parasitic conspecific eggs and incur very low rejection costs

Most host species of obligate interspecific brood parasites are under strong selection because such parasitism, e.g., that involving evictor nestmates, is highly costly. Egg rejection is one of the most efficient host defences against avian brood parasites. Many hosts have thus evolved egg-recognition ability and rejection behaviour. However, this defensive mechanism has not evolved in most species where only intraspecific brood parasitism occurs, probably because (1) the eggs of conspecific females are very similar in appearance, making egg rejection less likely to emerge, and (2) such parasitism is frequently less costly than interspecific parasitism. Using a captive population of house sparrows (Passer domesticus) with a low breeding density, we here provide new evidence showing that this species actually has a fine capacity to discriminate conspecific eggs and to eject them (44.2% of foreign eggs ejected) while incurring very low rejection costs (4.2% of own eggs ejected). This result contradicts those previously found in high-density house sparrow populations in which very high rejection costs and very high clutch desertion rates were reported, probably as a consequence of intraspecific competition and infanticide provoked by the high breeding density. The house sparrow has only rarely been reported as the host of an interspecific brood parasite, which implies that it is a newly described example of an altricial species in which egg ejection has evolved and is maintained in response to intraspecific brood parasitism.     

Neighborhood analyses of canopy tree competition along environmental gradients in New England forests.

We use permanent-plot data from the USDA Forest Service's Forest Inventory and Analysis (FIA) program for an analysis of the effects of competition on tree growth along environmental gradients for the 14 most abundant tree species in forests of northern New England, USA. Our analysis estimates actual growth for each individual tree of a given species as a function of average potential diameter growth modified by three sets of scalars that quantify the effects on growth of (1) initial target tree size (dbh), (2) local environmental conditions, and (3) crowding by neighboring trees. Potential growth of seven of the 14 species varied along at least one of the two environmental axes identified by an ordination of relative abundance of species in plots. The relative abundances of a number of species were significantly displaced from sites where they showed maximum potential growth. In all of these cases, abundance was displaced to the more resource-poor end of the environmental gradient (either low fertility or low moisture). The pattern was most pronounced among early successional species, whereas late-successional species reached their greatest abundance on sites where they also showed the highest growth in the absence of competition. The analysis also provides empirical estimates of the strength of intraspecific and interspecific competitive effects of neighbors. For all but one of the species, our results led us to reject the hypothesis that all species of competitors have equivalent effects on a target species. Most of the individual pairwise interactions were strongly asymmetric. There was a clear competitive hierarchy among the four most shade-tolerant species, and a separate competitive hierarchy among the shade-intolerant species. Our results suggest that timber yield following selective logging will vary dramatically depending on the configuration of the residual canopy, because of interspecific variation in the magnitude of both the competitive effects of different species of neighbors and the competitive responses of different species of target trees to neighbors. The matrix of competition coefficients suggests that there may be clear benefits in managing for specific mixtures of species within local neighborhoods within stands.     

Typifying conservation practitioners’ views on the role of education

Education is an established tool to enhance human–environment relationships, despite the lack of empirical evidence to support its use. We used theories of change to unpack assumptions about the role of education in conservation. We interviewed practitioners from 15 conservation organizations in Madagascar to typify implicit pathways of change and assess whether emerging pathways echo theoretical advances. Five pathways were drivers of change: increasing knowledge, changing emotional connection and changing traditional cultural practices, fostering leaders, diversifying outcomes, and influencing community and society. These pathways reflect existing sociopsychological theories on learning and behavioral change. Most interviewees’ organizations had a predominant pathway that was often combined with elements from other pathways. Most pathways lacked culturally grounded approaches. Our research reveals assumptions about the role of education in conservation and indicates that organizations had different ideas of how change happens. The diversity of practices reflects the complexity of factors that influence behavior. Whether this diversity is driven by local sociocultural context, interaction with other conservation approaches, or contingencies remains unclear. Yet, typifying the pathways of change and reflecting on them is the first step towards comprehensive evaluation of when and which pathways and interactions to promote.     

Modeling oil price uncertainty effects on economic growth in Mexico: a sector-level analysis

This paper analyzes the impact of international oil price uncertainty on the different economic sectors (primary, secondary, and tertiary) in Mexico in the period 1993:1–2020:4 through a bivariate structural vector autoregressive (VAR) model with a generalized autoregressive conditional heteroskedasticity (GARCH) in mean to capture the impact of oil volatility on economic growth at the sectoral level of economic activity. The results show that the uncertainty of the international price of oil has a differentiated effect on the different sectors of economic activity in Mexico since it does not influence the primary sector; it negatively impacts the secondary sector, and there is mixed evidence in the tertiary sector. Additionally, evidence is provided that both positive and negative shocks to the international oil price have asymmetric effects at the sectoral level in Mexico. The results highlight the need to implement public policies, at the country level, that help mitigate the effect of uncertainty in the oil market and promote economic stability at the sector level.

     

The distribution of 210Pb in human bone and its impact on methods for the retrospective estimation of 222Rn exposure from in vivo measurements

It is possible to estimate radon exposure to man retrospectively by the in vivo measurement of the decay product (210)Pb, which accumulates in the bones. For in vivo methods, knowledge of the distribution of (210)Pb in the skeleton is needed to determine the optimal site for measurement, the skull or the knee. In this study the activity of (210)Pb in a variety of bone samples from 3 individuals have been measured in vitro using underground gamma-ray spectrometry. The individuals were unlikely to have had elevated intakes of Rn. These measurements give baseline data on the bone massic activity of (210)Pb. They show that the massic activity is similar for each of these people and there are similar massic activities of (210)Pb in the skull and the knee of the 2 individuals for which the skull was measured. Additionally for 2 of the individuals trabecular and cortical bone were separated and massic activities were found to be strongly correlated indicating that the (210)Pb is associated with the hydroxyapatite.     

Hazard,vulnerability and coastal erosion risk assessment in Necochea Municipality,Buenos Aires Province,Argentina

This contribution determines the coastal erosion risk of Necochea and Quequén cities, Necochea Municipality, Buenos Aires Province (Argentina). Both risk components, hazard and vulnerability, were assessed by the construction of indices. The hazard index is composed of four indicators: the erosion or accretion rate, coastal geomorphology, storm waves effects, and sediment supply. The vulnerability index is comprised of land use/cover, demographic, life conditions, and work and consumption indicators, and includes population census data such as demographic, education, health, sanitary, economic, production, work and population exposure aspects. The analysis concluded that coastal erosion risk ranges from very low to high along the study area, Quequén yielding the highest values. Risk levels vary in both cities based on the uneven spatial distribution of hazard. The risk assessment developed herein constitutes a practical and adequate tool that can be utilized with other elements and tasks in the elaboration of a coastal management program.