The role of spatial processes and environmental determinants in microgeographic shell variation of the freshwater snail <Emphasis Type="Italic">Chilina dombeyana</Emphasis> (Bruguière, 1789)

Wildlife data often show spatial organization, demonstrating positive correlations either as a result of processes occurring over the landscape or due to the influence of spatially structured environmental variables. It is, thus, essential to consider non-random spatial structure when evaluating the underlying causes of biological variation. In this study, we analyzed the population structure of Chilina dombeyana shell morphology of 14 populations that are close geographically and belong to the same hydrographic basin. We utilized a variation partitioning approach to evaluate the importance of spatial processes, such as migration, acting over the landscape, and environmental characteristics, including habitat and hydrologic characteristics, and the occurrence of aquatic predators in promoting between population variation. Our results demonstrate spatially structured variation in C. dombeyana shell morphology, with populations living near each other having more similar shell sizes than populations living farther apart. The shell size variation partition indicated that both spatially structured environmental factors and genetic relationships resulting from migration or shared common ancestry may explain this pattern. Shell shape variation, in contrast, was found to be essentially under the influence of non-spatially structured environmental factors, with habitat and water characteristics accounting for about half of the total variation among populations. The large proportion of the variation in shell size that is spatially structured demonstrates that spatial structure on morphological traits might be strong and highlights the need to consider such phenomenon in intraspecific studies of phenotypic evolution.     

Removal of hydrogen sulfide from biogas by adsorption and photocatalysis: a review

Environmental Chemistry Letters - Biogas is a renewable fuel produced from modern biomass, yet biogas contains traces of hydrogen sulfide, a toxic compound, that must be removed before biogas...     

Northeast Arctic cod population persistence in the Lofoten-Barents Sea system under fishing.

Population growth, and hence the population's persistence, is affected by several factors such as climate, species interaction, and harvesting pressure. Proper resource management requires an understanding of these factors. We apply techniques based upon age-structured population matrices to analyze estimated stock sizes derived from annual bottom trawl sampling in the winter feeding area of northeast Arctic cod (Gadus morhua L.) from 1981 to 2003. We run generalized additive models to explain population growth rate by different explanatory variables. Cod population growth was found to be positively related to the abundance of capelin (Mallotus villosus Miller), negatively related to the number of cannibalistic cod with a two-year lag, and marginally positively related to the winter North Atlantic Oscillation index (NAO). This model remains true independently from the population status (i.e., fished or non-fished). Capelin abundance is the main variable that to some degree can be adjusted in order to maintain the population size at a given level of cod harvesting. Our results point to the importance of managing conjointly cod and capelin stocks.     

Interaction of short-term testosterone treatment with osmotic acclimation in the gilthead sea bream <Emphasis Type="Italic">Sparus auratus</Emphasis>

To assess the interaction between testosterone (T) treatment and acclimation to different salinities, seawater-acclimated gilthead sea bream (Sparus auratus) were implanted with slow-release coconut oil implants alone (control) or containing T (5 μg/g body mass). After 5 days, eight fish of control and T-treated groups were sampled. The same day, eight fish of each group were transferred to low salinity water (LSW, 6 ppt, hypoosmotic test), seawater (SW, 38 ppt, control test) and high salinity water (HSW, 55 ppt, hyperosmotic test) and sampled 9 days later. Gill Na⁺, K⁺-ATPase activity increased in HSW-acclimated fish with respect to SW- and LSW-acclimated fish in both control and T-treated groups. Kidney Na⁺, K⁺-ATPase activity was also enhanced in HSW-acclimated fish, but only in T-treated group. From a metabolic point of view, most of the changes observed can be attributed to the action of salinity and T treatment alone, since few interactions between T treatment and osmotic acclimation to different salinities were observed. Those interactions included in treated fish: in the liver, decreased capacity in using glucose in fish acclimated to extreme salinities; in the gills, decreased capacity in using amino acids in HSW; in the kidneys increased capacity in using amino acids in extreme salinities; and in the brain, decreased glycogen and acetoacetate levels of fish in LSW.     

Tropical fishes in a temperate sea: evolution of the wrasse <Emphasis Type="Italic">Thalassoma pavo</Emphasis> and the parrotfish <Emphasis Type="Italic">Sparisoma cretense</Emphasis> in the Mediterranean and the adjacent Macaronesian and Cape Verde Archipelagos

The northeastern Atlantic and the Mediterranean Sea share geological histories and display great faunal affinities. The majority of the Mediterranean species have Atlantic origins, with a few species with tropical affinities. These include the parrotfish Sparisoma cretense and the wrasse Thalassoma pavo that are restricted to the subtropical northeastern Atlantic, the Macaronesian archipelagos (Azores, Madeira, and Canaries) and the southern Mediterranean. The Pleistocene glaciations have been described as having different effects on the fauna of the two regions. During glacial peaks, Mediterranean waters remained warmer than those of the adjacent Atlantic. Within the eastern Atlantic, the effects of Pleistocene glaciations were differentiated. Here, we perform a comparative analysis focusing on T. pavo and S. cretense populations from the northeastern Atlantic and the Mediterranean to assess the effects of Pleistocene glaciations in these two species. Sequences from the mitochondrial control region were obtained and analyzed combining phylogeographic and demographic approaches. Gene flow between Atlantic and Mediterranean populations was shown to be very high. The Mediterranean populations of T. pavo and S. cretense showed high levels of genetic diversity, even in the eastern basin, pointing to an ancient colonization event. This suggests that both species must have been able to persist in the Mediterranean during the cold Pleistocene periods. Historical migration estimates revealed a Mediterranean towards Atlantic trend in the case of T. pavo, which may reflect the re-colonization of areas in the Atlantic by fish that survived the cold phases in relatively warmer Mediterranean refugia. Our data also showed that within the Macaronesian Archipelagos, migrations occurred from Madeira towards the Azores, for both T. pavo and S. cretense, thus supporting a post-glacial colonization of the Azores by fish that persisted in the warmer region of Madeira. Similar geographic distributions, thermal affinities, and means of dispersion for T. pavo and S. cretense resulted in a similar response to the effects of Pleistocene glaciations, as evidenced by identical phylogeographic patterns.     

Ranging patterns of bottlenose dolphins living in oceanic waters: implications for population structure

Very little is known about the ecology of common bottlenose dolphins (Tursiops truncatus) living in oceanic waters. This study investigated the ranging and residence patterns of bottlenose dolphins occurring in the Azores (Portugal), the most isolated archipelago in the North Atlantic. Data were collected during standardized boat-based surveys conducted over a 6-year period in an area of approximately 5,400 km² (main study area). To investigate the extent of movements of individual animals, non-systematic surveys were also conducted outside this area. Only 44 individuals out of 966 identified were frequently sighted within and between years. The remaining individuals were either temporary migrants from within or outside the archipelago, or transients. Resident dolphins showed strong geographic fidelity to the area. Long-distance movements (of almost 300 km), consistent with foraging or exploratory trips, were observed among non-resident dolphins. Home range size was estimated for 31 individuals sighted ≥10 times. Range areas of these dolphins varied in size and location, but considerable overlap was observed in the areas used, suggesting the absence of habitat partitioning between resident and non-resident dolphins. Estimates of home range size of bottlenose dolphins in the Azores were found to be considerably larger than those previously reported for this species. It is hypothesized that dolphins living in the Azores carry out extensive movements and have large home ranges in response to the lower density and patchy distribution of prey compared to other areas. The extensive ranging behaviour and the lack of territoriality provide an opportunity for interbreeding between dolphins associated with different islands, thus preventing genetic differentiation within the population of the Azores.     

Are faecal hormone levels linked to winter progression,diet quality and social rank in young ungulates ? An experiment with white-tailed deer (<Emphasis Type="Italic">Odocoileus virginianus</Emphasis>) fawns

Hormones play a central role in the physiology and behaviour of animals. The recent development of noninvasive techniques has increased information on physical and social states of individuals through hormone measurements. The relationships among hormones, life history traits and behaviours are, however, still poorly known. For the first time, we evaluated natural winter glucocorticoid and testosterone levels in young ungulates in relation to winter progression, diet quality and social rank. Overwinter, levels of glucocorticoid and testosterone decreased, possibly due to the decline of fawns’ body mass. The relationships between hormone levels and diet quality were surprising: Fawns fed the control diet presented higher glucocorticoid and lower testosterone levels then fawns fed the poor diet, suggesting that control fawns faced a higher nutritional stress than those on the poor diet. Similarly to other studies on social mammals, we found no relationship between faecal glucocorticoid levels and social rank, suggesting that social stress was similar for dominant and subordinate fawns during winter. Testosterone levels were not correlated to social rank as found previously in groups of individuals forming stable social hierarchies and maintaining stable dominance relationships. The simultaneous suppression of glucocorticoid and testosterone levels suggests for the first time that young ungulates present a hormonal strategy to prevent fast depletion of limited proteins and fat resources during winter.     

Ecological risk assessment of metal and hydrocarbon pollution in sediments from an urban tropical estuary: Tijuca lagoon (Rio de Janeiro,Brazil)

Environmental Science and Pollution Research - Urban tropical lagoons are often impacted by eutrophication, metal, and polycyclic aromatic hydrocarbon (PAH) contamination, but the toxicity of their...     

Green synthesis silver nanoparticles Bougainvillea glabra Choisy/LED light with high catalytic activity in the removal of methylene blue aqueous solution

In this study, we evaluated, in a pioneering way, the influence of wavelengths from the decomposition of white light on the production and physicochemical properties of silver nanoparticles (AgNPs). Bearing in mind a process of green synthesis, an extract of the bracts of Bougainvillea glabra Choisy (BgC) was used, a species native to tropical and subtropical regions and frequently used in ornamentation, possessing in its photochemical composition, biomolecules capable of acting as reducing agents for convert Ag⁺ to Ag⁰. We used light-emitting diodes (LED) to obtain the desired wavelengths (violet, blue, green, yellow, orange, and red) in the test called rainbow, and we evaluated the obtaining of AgNPs compared to white LED light, nature, and absence of light. In the rainbow assay, we obtained a gradual increase in the intensity of the plasmonic band resonance from the red wavelength (0.124 ± 0.067 a.u.) to violet (0.680 ± 0.199 a.u.), indicating a higher reaction yield in obtaining AgNPs. Smaller hydrodynamic sizes (approximately 150 nm) at more energetic wavelengths (violet, blue, and green) about less energetic wavelengths (yellow, orange, and red) (approximately 400 nm) were obtained. Analysis by SEM microscopy, FTIR spectroscopy, and X-ray diffraction indicates the presence of silver nanoparticles in all LED colors used together with white LED light and Laboratory light (natural light). Due to the high environmental demand to remove pollutants from water sources, including textile dyes, we applied AgNPs/BgC to remove methylene blue (MB) dye from an aqueous solution. A minimum removal percentage greater than 65%, with emphasis on formulations synthesized by the colors of violet LED (84.27 ± 2.65%) and orange LED (85.91 ± 1.95%), was obtained.