Symbolic and social dimensions in the economic production of seaweed

Abstract: Based on the thesis of ‘deagrarianisation’ of farming economies, work on sustainable rural livelihoods (SRL) has successfully captured the agency of rural producers as they diversify their livelihoods to minimise risk. SRL captures a complex interplay of local and global factors, as well as the synergies emanating from natural (environmental), economic and social capital that underpin diversification. The framework has been found useful for analyses of change in coastal, marine‐based livelihoods. However, agency at the local level implies equal power to accept and reject development interventions. The way groups diversify or use the options open to them depends as much on access to resources (the means), as on how that access is interpreted (the meaning), and the latter dimension is a creative (unpredictable) one. New introduced forms of economic activities, in this case seaweed farming, can be assigned meaning by participants that were unanticipated by change agents. Livelihood diversification through seaweed cultivation on Banggi island off Kudat, northern Sabah (East Malaysia) is not attained by economic factors alone but also by the meaning attached to the activity.     

Assessment of the uniformity of wheat and tomato varieties at DNA microsatellite loci

By analysing a number (20–38) of individuals from selected varieties of wheat and tomato, we have been able to assess intra-varietal uniformity at certain micro satellite (simple sequence repeat, SSR) loci. In total, 45 varieties of wheat were analysed at between 7–9 different SSR loci, and 10 varieties of tomato were analysed at six loci. The results showed that there was variation both between varieties and between microsatellites in the degree of non-uniformity observed, and it was possible to identify a number of different probable sources of non-uniformity. Twenty-four of the wheat varieties and nine of the tomato varieties were sufficiently uniform to meet the standards currently applied for distinctness, uniformity and stability (DUS) testing using phenotypic characteristics. The implications for the potential future use of SSRs in DUS testing are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Seroprevalence of psittacine beak and feather disease in wild psittacine birds in New South Wales

SUMMARY A haemagglutination inhibition assay was used to detect antibody to psittacine beak and feather disease virus in sera from wild sulphur crested cockatoos (Cacatua galerita), galahs (Eolophus roseicapillus), short-billed corellas (Cacatua sanguinea), eastern long-billed corellas (Cacatua tenuirostris) and other psittacine birds in New South Wales. The seroprevalence of psittacine beak and feather disease ranged from 41% to 94% in different flocks, indicating infection with the virus is widespread in wild populations.     

Identification of toxigenic Pasteurella multocida in atrophic rhinitis of pigs by in vitro characterisation

Toxigenic strains of Pasteurella multocida were readily differentiated from non-toxigenic strains by an agarose overlay method using bovine turbinate cells or bovine lung cells. Cells which were young and densely confluent were best suited to this assay. The incubation period required to distinguish toxigenic strains was dependent on the confluence of the monolayers, which was affected by the seeding rate, cell passage level and growth time prior to overlay. The agarose overlay method correctly identified 11 of 11 reference strains of Pasteurella multocida, and visible cytotoxic changes were present in the monolayers after 48 to 65 h. Outbreaks of the enzootic form of atrophic rhinitis in 2 New South Wales piggeries were associated with the isolation of toxigenic type D strains of P. multocida.     

The effects of antigenic competition on the efficacy of multivalent footrot vaccines

SUMMARY A multivalent footrot vaccine has been developed, containing pilus antigens produced in recombinant Pseudomonas aeruginosa and representing all nine serogroups of Dichelobacter (Bacteroides) nodosus commonly recognised in the field. The responses of sheep to the multivalent vaccine have been compared with those to monovalent vaccines representing only a single serogroup. Antigenie competition between serogroups occurred in sheep immunised with the multivalent formulation, but high levels of protection were still achieved. The study showed that in multivalent footrot vaccines, antigenic competition is predominantly due to the presence of a family of immunologically-related pilus antigens rather than to interference by extraneous proteins.     

Delayed luteolysis and suppression of the pulsatile release of oxytocin after indomethacin treatment in the goat

Luteolysis in the goat was characterised by the pulsatile appearance of both oxytocin and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM), the primary pulmonary metabolite of prostaglandin (PG) F2 alpha, in the peripheral circulation. The episodic, surge release of oxytocin was superimposed on declining levels which paralleled the fall in progesterone concentrations. Daily subcutaneous administration of the prostaglandin synthetase inhibitor indomethacin (10 mg kg-1) between days 11 and 16, delayed luteolysis and suppressed both the decline in oxytocin concentrations and the pulsatile appearance of both oxytocin and PGFM in the peripheral circulation. Although there was little evidence of the release of the two hormones being synchronised, the results suggest that PGF2 alpha may stimulate pulsatile oxytocin release at luteolysis.     

Impact of biodiversity-climate futures on primary production and metabolism in a model benthic estuarine system

Background

A territory as a prerequisite for breeding limits the maximum number of breeders in a given area, and thus lowers the proportion of breeders if population size increases. However, some territorially breeding animals can have dramatic density fluctuations and little is known about the change from density-dependent processes to density-independence of breeding during a population increase or an outbreak. We suggest that territoriality, breeding suppression and its break-down can be understood with an incomplete-control model, developed for social breeders and social suppression.

Results

We studied density dependence in an arvicoline species, the bank vole, known as a territorial breeder with cyclic and non-cyclic density fluctuations and periodically high densities in different parts of its range. Our long-term data base from 38 experimental populations in large enclosures in boreal grassland confirms that breeding rates are density-regulated at moderate densities, probably by social suppression of subordinate potential breeders. We conducted an experiment, were we doubled and tripled this moderate density under otherwise the same conditions and measured space use, mortality, reproduction and faecal stress hormone levels (FGM) of adult females. We found that mortality did not differ among the densities, but the regulation of the breeding rate broke down: at double and triple densities all females were breeding, while at the low density the breeding rate was regulated as observed before. Spatial overlap among females increased with density, while a minimum territory size was maintained. Mean stress hormone levels were higher in double and triple densities than at moderate density.

Conclusions

At low and moderate densities, breeding suppression by the dominant breeders, But above a density-threshold (similar to a competition point), the dominance of breeders could not be sustained (incomplete control). In our experiment, this point was reached after territories could not shrink any further, while the number of intruders continued to increase with increasing density. Probably suppression becomes too costly for the dominants, and increasing number of other breeders reduces the effectiveness of threats. In wild populations, crossing this threshold would allow for a rapid density increase or population outbreaks, enabling territorial species to escape density-dependency.