Ontogeny of diving behaviour in the Australian sea lion: trials of adolescence in a late bloomer

1.Foraging behaviours of the Australian sea lion (Neophoca cinerea) reflect an animal working hard to exploit benthic habitats. Lactating females demonstrate almost continuous diving, maximize bottom time, exhibit elevated field metabolism and frequently exceed their calculated aerobic dive limit. Given that larger animals have disproportionately greater diving capabilities, we wanted to examine how pups and juveniles forage successfully.
2.Time/depth recorders were deployed on pups, juveniles and adult females at Seal Bay Conservation Park, Kangaroo Island, South Australia. Ten different mother/pup pairs were equipped at three stages of development (6, 15 and 23 months) to record the diving behaviours of 51 (nine instruments failed) animals.
3. Dive depth and duration increased with age. However, development was slow. At 6 months, pups demonstrated minimal diving activity and the mean depth for 23-month-old juveniles was only 44 ± 4 m, or 62% of adult mean depth.
4. Although pups and juveniles did not reach adult depths or durations, dive records for young sea lions indicate benthic diving with mean bottom times (2·0 ± 0·2 min) similar to those of females (2·1 ± 0·2 min). This was accomplished by spending higher proportions of each dive and total time at sea on or near the bottom than adults. Immature sea lions also spent a higher percentage of time at sea diving.
5. Juveniles may have to work harder because they are weaned before reaching full diving capability. For benthic foragers, reduced diving ability limits available foraging habitat. Furthermore, as juveniles appear to operate close to their physiological maximum, they would have a difficult time increasing foraging effort in response to reductions in prey. Although benthic prey are less influenced by seasonal fluctuations and oceanographic perturbations than epipelagic prey, demersal fishery trawls may impact juvenile survival by disrupting habitat and removing larger size classes of prey. These issues may be an important factor as to why the Australian sea lion population is currently at risk.

A spill-over theory of international trade unionism

This paper use neo-functionalist and institutionalist theories of geo-political integration to develop a theory of international trade unionism. In brief, the theory asserts that the type of international ‘context’ in which international trade unions operate presupposes the types of ‘imperatives’ that will dominate their interests and concerns. These imperatives are taken to operate along one of three dimensions - industrial, political and ideological, and are seen as evolving in accordance with the ‘logic of spill-over’ in global and sub-global integration processes. Using this interpretation the discussion provides reasons as to why ideological imperatives have historically dominated international trade union thinking, the only exception being regional trade unions operating in Europe, which have evolved beyond the ideological to embrace industrial and political imperatives in their modes of organisation and operation.

Edward Shils' theory of tradition

Edward Shils presented his book Tradition (1981) as the first extensive study of the subject. This article casts light on Shils' multifaceted understanding of tradition, comprising pragmatic, Burkean, veridical, and evolutionist perspectives. His typology of traditions is noted, and his view of institutional bearers of tradition described. In assessing Shils' theory, however, we find that it overreaches, collapsing differences that exist between traditions, transmissions, and the traditional.

Towards a critical theory of sport management

This article argues for the theoretical and practical possibilities of applying critical theory to sport management research.

Vector Theory of Spontaneous Lorentz Violation

Classical electromagnetism predicts two massless propagating modes, which are known as the two polarizations of the photon. On the other hand, if the Lorentz symmetry of classical electromagnetism is spontaneously broken, the new theory will still have two massless Nambu-Goldstone modes resembling the photon. If the Lorentz symmetry is broken by a bumblebee potential that allows for excitations out of the minimum, then massive modes arise. Furthermore, in curved spacetime, such massive modes will be created through a process other than the usual Higgs mechanism because of the dependence of the bumblebee potential on both the vector field and the metric tensor. Also, it is found that these massive modes do not propagate due to the extra constraints.

A theory of injustice: the flip side of the relocation coin in Australia

Problems attached to relocation cases in Australia because of geographical and cultural reasons - the best interests of the child principle inherently promotes injustice in relocation cases - operation of Part VII of the Family Law Act in the context of relocation cases - assessment of the best interests of the child principle in Australian relocation cases - responsibility of contact parents - reforming Australian law to promote an equality of interests.