Transport of brine shrimps via the digestive system of migratory waders: dispersal probabilities depend on diet and season

Waterbirds are known to disperse invertebrate propagules that survive gut passage, but there is very little information about how the probability of dispersal changes at different times of the annual cycle when birds move in different directions, or how it is affected by changes in diet. We studied internal transport of brine shrimp Artemia cysts by migratory waders in the Odiel saltworks in south-west Spain. Viable cysts of parthenogenetic Artemia were abundant in the faeces and regurgitated pellets of redshank Tringa totanus, pellets of spotted redshank T. erythropus, and faeces of black-tailed godwit Limosa limosa during spring and/or autumn migrations in 2001–2002, but were not recorded during winter. Godwits did not produce pellets, and spotted redshank faeces were not sampled. Significant correlations between the number of cysts in a pellet or faecal sample and the proportion of that sample constituted by Artemia adults suggested that most cysts were ingested while in the ovisacs of gravid females. The proportion of cysts destroyed during digestion increased when accompanied by harder food items or grit, and when fewer cysts were ingested. The median number of intact cysts was higher in redshank faeces than in their pellets, but cysts extracted from pellets were more likely to hatch. A higher proportion of redshank pellets contained Artemia cysts in spring than in autumn, but more redshank migrated through the area in autumn. Significantly fewer cysts were recorded in redshank pellets in winter than in spring or autumn. Our results confirm that there is potential for long-distance dispersal of Artemia cysts via waders during both northwards (spring) and southwards (autumn) migrations.     

Spatial ecology and residency patterns of adult great barracuda (<Emphasis Type="Italic">Sphyraena barracuda</Emphasis>) in coastal waters of The Bahamas

Great barracuda (Sphyraena barracuda) were implanted with acoustic telemetry transmitters (n = 42) and monitored within a stationary acoustic receiver array (n = 53 receivers) in The Bahamas to examine residency, seasonal movements, and habitat use. Barracuda were monitored for up to 980 days and remained within the array area ~33% (median value) of the time. Most tagged barracuda were transient and would often disappear from the array for months at a time, particularly in the summer where they were usually last detected on receivers located in deeper shelf habitats, and then return at other times in the year. Habitat use across the footprint of the array differed, with most detections occurring in coastal areas and comparatively fewer in deeper mosaic or shelf habitats. Linear home range estimates revealed that some barracuda moved >12 km within a single day and are capable of migrating >100 km to other islands in the Bahamian Archipelago. Our results provide some of the first telemetry data for this apex marine predatory fish and the first reliable information on the residency and localized seasonal movements of adult great barracuda in the coastal waters of the Western Atlantic.     

Livestock mortality in pastoralist herds in Ethiopia and implications for drought response

Participatory epidemiology methods were employed retrospectively in three pastoralist regions of Ethiopia to estimate the specific causes of excess livestock mortality during drought. The results showed that starvation/dehydration accounted for between 61.5 and 100 per cent of excess livestock mortality during drought, whereas disease‐related mortality accounted for between 0 and 28.1 per cent of excess mortality. Field observations indicate that, in livestock, disease risks and mortality increase in the immediate post‐drought period, during rain. The design of livelihoods‐based drought response programmes should include protection of core livestock assets, and it should take account of the specific causes of excess livestock mortality during drought and immediately afterwards. This study shows that, when comparing livestock feed supplementation and veterinary support, relatively more aid should be directed at the former if the objective is to protect core livestock during drought. Veterinary support should consider disease‐related mortality in the immediate post‐drought period, and tailor inputs accordingly.     

Risky driving and the perception of motorcycle accident causes among chinese motorcyclists in Hong Kong

Objective: The primary purposes of this study were to explore the relationship between risk-taking acts while driving motorcycles and perceived causes of motorcycle accidents, as well as their contribution to active involvement in traffic accidents among Chinese motorcyclists in Hong Kong. Active involvement means the riders was likely at fault for the crash. Methods: A total of 774 motorcyclists were recruited, of whom 292 had been involved in active motorcycle accident in the previous 3?years. All were asked to fill in a questionnaire, which was developed to assess their risk-taking acts while driving a motorcycle and perception of motorcycle accident causes. Results: The results of the study revealed 3 dimensions of accident causes, namely, driving-related, environment-related, and belief-related causes. These motorcycle accident causes were correlated with risk-taking acts while driving a motorcycle. A multivariate logistic regression analysis showed that risk-taking acts while driving motorcycles (adjusted odds ratio [OR]: 1.036, 95% confidence interval [CI]: 1.020-1.052), perception of driving-related cause (adjusted OR: 0.941, 95% CI: 0.916-0.967), and belief-related cause (adjusted OR: 1.134, 95% CI: 1.088-1.182) were significant factors contributing to involvement in active traffic accidents by motorcycle riders after controlling for concurrent demographic variables. Conclusions: The study highlights that perceived causes of motorcycle accidents are multidimensional, including those areas related to driving, the environment, and beliefs. It substantiates previous studies that a higher degree of driving-related risk perception is related to a lower degree of risk-taking acts while driving. Further research is needed to understand why belief-related causes, sometimes called superstitions, lead riders to believe that it is beyond their ability to affect accident causation and prevention.     

Bicyclist fatalities involving heavy goods vehicles: gender differences in risk perception, behavioral choices, and training

Objectives: Females are typically involved in fewer collisions when pedal cycling than males. However, female cyclists appear to be overrepresented in the number of fatal collisions involving heavy goods vehicles (HGVs). These collisions often involve cyclists passing HGVs on the side furthest from the HGV driver (nearside). It is hypothesized that this pattern of fatalities may be partly due to differences in how males and females perceive the risk associated with various cycling maneuvers. It is also hypothesized that this difference may be overcome with advanced training. Methods: 4,596 UK cyclists completed an online questionnaire in which they reported their level of cycle training and rated the risk they perceived to be associated with various cycling maneuvers, the likelihood that they would engage in them, and history of collision involvement. Results: Females perceived a slightly greater level of risk to be associated with cycling. However, males differentiated between the risks involved in nearside and offside overtaking to a greater extent than females. Risk perception was significantly correlated with the reported likelihood that participants would engage in risky maneuvers such as overtaking on the nearside and also with past collision prevalence. Advanced cycling training was correlated with higher levels of perceived risk associated with overtaking on the nearside; however, basic cycle training was not. Conclusions: Cyclists who do not correctly differentiate between the risks associated with nearside and offside overtaking may be more at risk of being involved in HGV-related collisions. Advanced cycling training is linked to more accurate risk perception. To reduce fatalities, public awareness campaigns should focus on the increased risk of nearside overtaking and encourage cyclists to take advanced training.     

Attachment of oysters to natural substrata by biologically induced marine carbonate cement

Oysters live permanently immobilised by cementation of the left valve to a hard substrate. The contact zone between oysters and natural substrata has been analysed using SEM imaging, electron dispersive X-ray microanalysis, electron backscatter diffraction and Raman spectroscopy and reveals the influence of both biogenic and non-biogenic processes in oyster cementation. Original adhesion is brought about by secretion of an organic component that acts as a nucleating surface onto which crystals precipitate. These crystals have a random orientation and are composed of high Mg calcite. This suggests that the crystals nucleating on the glue substrate are outwith the biological control experienced by the shell biomineralisation process and are formed by inorganic precipitation from seawater. It is proposed that oysters do not control or secrete crystalline cement. Instead, they adhere by secretion of an organic film onto which crystals precipitate from seawater.     

Testing the Established Hydrogeologic Model of Source Water to the Amargosa River Basin,Inyo and San Bernardino Counties,California

The current conceptual hydrogeologic model established for source water to the Amargosa River was tested in order to help inform management decisions regarding the Amargosa River's Federal designation as Wild and Scenic through an Act of Congress. The limited availability of water in this region results in the critical need for effective management in the basin to maintain its Wild and Scenic attributes inclusive of habitat for several endangered and threatened species. The use of forensic tools and integration of multiple lines of geologic, hydrogeologic, geochemical, and stable isotopic evidence suggest that the simple historical model for primary groundwater transport through this region is incorrect and that a large supply of regional baseflow does not provide the hydrogeological foundation of the Amargosa River basin. Data collected is consistent with an alternative model requiring complex source mixing and shallow alluvial groundwater that supports river flow. This conclusion also suggests Wild and Scenic conditions in this basin are more precarious than previously understood.