Who Eats Whom in a Pool? A Comparative Study of Prey Selectivity by Predatory Aquatic Insects

Predatory aquatic insects are a diverse group comprising top predators in small fishless water bodies. Knowledge of their diet composition is fragmentary, which hinders the understanding of mechanisms maintaining their high local diversity and of their impacts on local food web structure and dynamics. We conducted multiple-choice predation experiments using nine common species of predatory aquatic insects, including adult and larval Coleoptera, adult Heteroptera and larval Odonata, and complemented them with literature survey of similar experiments. All predators in our experiments fed selectively on the seven prey species offered, and vulnerability to predation varied strongly between the prey. The predators most often preferred dipteran larvae; previous studies further reported preferences for cladocerans. Diet overlaps between all predator pairs and predator overlaps between all prey pairs were non-zero. Modularity analysis separated all primarily nectonic predator and prey species from two groups of large and small benthic predators and their prey. These results, together with limited evidence from the literature, suggest a highly interconnected food web with several modules, in which similarly sized predators from the same microhabitat are likely to compete strongly for resources in the field (observed Pianka’s diet overlap indices >0.85). Our experiments further imply that ontogenetic diet shifts are common in predatory aquatic insects, although we observed higher diet overlaps than previously reported. Hence, individuals may or may not shift between food web modules during ontogeny

Teachers' self-efficacy, achievement goals, attitudes and intentions to implement the new Greek physical education curriculum

The network of relations between Physical Education (PE) teachers' self-efficacy, goal orientations, attitudes, intentions and behaviours concerning the implementation of a new PE curriculum was examined. Participants were 290 Greek junior high school PE teachers. Two years after the introduction of the new curriculum, participants responded to de-identified questionnaires with acceptable psychometric properties. Mastery-oriented and high self-efficacious teachers had positive attitudes towards the new curriculum, implemented the biggest number of teaching plans and they intended to do the same in the future. Performance approach goal orientation had low positive relationship with the implementation of teaching plans and no relationship with intention to do the same in the future, while performance avoidance goal was not related to any determinant of curriculum implementation and intention. The effects of mastery goal orientation on intention and behaviour were mediated by self-efficacy to achieve an educational aim which is an end in itself, that is, the promotion of students' self-regulation in exercise settings. The effects of performance approach goal orientation on behaviour were mediated by self-efficacy to achieve a curricular goal which is a means to promote other educational aims, that is, the adoption of student-centred teaching styles. Teaching experience was negatively related to implementation of the new curriculum and with most of its determinants. Strategies aiming to strengthen teachers' self-efficacy, mastery goals, attitudes and intentions to implement a new curriculum are suggeste

Drilling Crew

Using air drills to prepare the bedrock for the foundation of Grand Coulee Dam.https://dc.ewu.edu/blonk/1061/thumbnail.jp