Passive flow through an unstalked intertidal ascidian: Orientation and morphology enhance suspension feeding in Pyura stolonifera

Passive flow is believed to increase the gains and reduce the costs of active suspension feeding. We used a mixture of field and laboratory experiments to evaluate whether the unstalked intertidal ascidian Pyura stolonifera exploits passive flow. We predicted that its orientation to prevailing currents and the arrangement of its siphons would induce passive flow due to dynamic pressure at the inhalant siphon, as well as by the Bernoulli effect or viscous entrainment associated with different fluid velocities at each siphon, or by both mechanisms. The orientation of P. stolonifera at several locations along the Sydney-Illawarra coast (Australia) covering a wide range of wave exposures was nonrandom and revealed that the ascidians were con- sistently oriented with their inhalant siphons directed into the waves or backwash. Flume experiments using wax mod- els demonstrated that the arrangement of the siphons could induce passive flow and that passive flow was greatest when the inhalant siphon was oriented into the flow. Field exper- iments using transplanted animals confirmed that such an orientation resulted in ascidians gaining food at greater rates, as measured by fecal production, than when oriented perpendicular to the wave direction. We conclude that P. stolonifera enhances suspension feeding by inducing pas- sive flow and is, therefore, a facultatively active suspension feeder. Furthermore, we argue that it is likely that many other active suspension feeders utilize passive flow and, therefore, measurements of their clearance rates should be made under appropriate conditions of flow to gain ecolog- ically relevant results.

Home range, habitat selection and diet of foxes (vulpes vulpes) in a semi-urban riparian environment

Between 2000 and 2002 the home range, habitat selection and diet of foxes were examined in the Dandenong Creek Valley, Melbourne, Australia. The mean home range was 44.6 ha (range 19.2–152.6 ha). A significant selection towards blackberry and gorse used as diurnal shelter was found during the day with an active avoidance of less structurally complex vegetation types. Although there was obvious selection of certain habitats, the diet of the foxes was highly general and opportunistic and thus offers little potential as a factor to manipulate in order to reduce fox abundance. Given the strong preference for blackberry and gorse as a shelter resource, a habitat-manipulation strategy is suggested whereby patches of blackberry and gorse are removed and replaced with less structurally complex vegetation. Such a strategy has the potential to influence the density of foxes in semi-urban riparian environments such as those discussed in this study.

What helps children to be more active and less sedentary? Perceptions of mothers living in disadvantaged neighbourhoods

Background Increasing children's participation in physical activity and decreasing time spent in sedentary behaviours is of great importance to public health. Despite living in disadvantaged neighbourhoods, some children manage to engage in health-promoting physical activity and avoid high levels of screen-based activities (i.e. watching TV, computer use and playing electronic games). Understanding how these children manage to do well and whether there are unique features of their home or neighbourhood that explain their success is important for informing strategies targeting less active and more sedentary children. The aim of this qualitative study was to gain in-depth insights from mothers regarding their child's resilience to low physical activity and high screen-time.

Methods Semi-structured face-to-face interviews were conducted with 38 mothers of children who lived in disadvantaged neighbourhoods in urban and rural areas of Victoria, Australia. The interviews were designed to gain in-depth insights about perceived individual, social and physical environmental factors influencing resilience to low physical activity and high screen-time.

Results Themes relating to physical activity that emerged from the interviews included: parental encouragement, support and modelling; sports culture in a rural town; the physical home and neighbourhood environment; child's individual personality; and dog ownership. Themes relating to screen-time behaviours encompassed: parental control; and child's individual preferences.

Conclusions The results offer important insights into potential avenues for developing ‘resilience’ and increasing physical activity and reducing screen-time among children living in disadvantaged neighbourhoods. In light of the negative effects of low physical activity and high levels of screen-time on children's health, this evidence is urgently needed.

Parents' and children's views on whether active video games are a substitute for the 'real thing'

Background:
Research has examined the energy cost associated with playing seated and active video games (AVGs), but not whether AVGs may benefit fundamental movement skills (FMS) in typically developing children. Improving FMS proficiency is a priority given its association with physical activity. This study aimed to identify children’s and parents’ perceptions of: (1) AVGs as a tool for developing FMS and (2) whether any skills gained during AVG play had potential to transfer to real life.

Methods:
This qualitative descriptive study included 29 parents of children aged 9–10 years who participated in semi-structured telephone interviews and 34 children who participated in six group discussions at school. Interview and discussion group data were recorded, transcribed and analysed thematically.

Results:
Parents and children had different perspectives on the potential of AVGs for FMS, which largely rested on different views of ‘reality’. Parents felt AVGs were not a substitute for the ‘real thing’, and therefore had limited FMS benefits. Overall, parents thought any FMS gained through AVGs would have poor transferability to ‘real life’. In contrast, children had a more fluid and expansive view of reality which incorporated both ‘real life’ and ‘virtual’ space. Whilst children could articulate limitations of AVGs for skill learning, they still reported extensive use of AVGs as a learning tool for movement skill, and considered that skill acquisition was highly transferable.

Conclusions:
Despite contrasting beliefs from parents and children, children used AVGs for FMS learning. Future research needs to determine whether actual FMS benefits are gained through AVGs.