We describe the structure of the macrofaunal community inhabiting holdfasts of the kelp Ecklonia radiata sampled over a 4 year period on the mid-north coast of New South Wales, Australia. Both the physical and biological structures of the holdfast are described. Analyses focused on the relationships between holdfast volume and a range of summary community statistics (number of species, total abundance, total biomass) as well as the description of successional patterns with increasing holdfast size for the common species, higher taxa and trophic groups. The holdfast habitat suppons a diverse faunal community that was dominated by polychaete worms and amphipod crustaceans, which together accounted for 78% of the total number of organisms sampled. Many of the species present have a much wider distribution in both intertidal and sublittoral marine habitats. Successional patterns within the holdfast were from a community dominated by small worms with a predominance of deposit-feeding strategies to one with a greater representation of amphipods with omnivorous feeding strategies. There was also a trend to increasing mean size of individuals with increasing holdfast size, which may be attributable to either growth of individuals over time or physical hmitations (smaller spaces) in smaller holdfasts. The analysis of differences in spatial patterns for summary statistics of the community structure (species number, number of individuals, faunal density) suggested that small-scale variabihty (sites within locations) was more important than larger scale variability (between locations) and that the most easterly sites at each location supported the highest species count and number of individuals.

Most of Australia’s sheep rangelands are enclosed by a dingo-proof fence. Within these rangelands, where dingoes (Canis lupus dingo) are rare, red kangaroos (Macropus rufus) are considered to be food limited because their numbers respond to fluctuations in pasture biomass that are driven by highly variable rainfall. Outside this region, where dingoes are common, kangaroo densities are generally substantially lower, suggesting that dingoes are an important limiting factor. However, it is unclear whether dingoes can regulate kangaroo populations. In this study, red kangaroo and emu (Dromaius novaehollandiae) numbers were monitored for varying periods during 1978–92 by aerial survey on both sides of the dingo fence in three areas in the north of the South Australian pastoral zone. Densities of red kangaroos and emus were lower outside the fence, although the disparity varied between areas and over time. The similarity in the environments on both sides of the fence and the marked step in kangaroo density at the fence are consistent with dingoes strongly limiting these prey populations. In the north-east of the pastoral zone, where kangaroo and emu densities are greatest, the contrast in density across the fence was most pronounced. Furthermore, the trends in density over time differed across the fence. Outside the fence, red kangaroos and emus remained at low densities following drought as dingo numbers increased. Inside the fence, red kangaroo and emu populations showed a ‘typical’ post-drought recovery. The data therefore suggest that, in some situations, dingoes may not simply limit red kangaroo and emu populations, but also regulate them. For this to occur, predation rate would need to be density dependent at low prey densities. The availability of alternative prey, and the reduction in the numbers of all prey during drought may provide the mechanism.

No abstract

In many parts of south-eastern Australia, native riparian vegetation has been cleared and exotic willows planted. In order to evaluate some of the possible effects of this practice, the decomposition and colonisation by invertebrates of the leaves of three native plant species along with those of willow were examined.Decomposition of leaves of the willow Salix babylonica L. and the indigenous macrophyte Myriophyllum propinquum A. Cunn. was much faster than for leaves of the indigenous trees Eucalyptus blakelyi Maiden and Casuarina cunninghamiana Miq. Both macroinvertebrates and current were found to have a significant influence upon decomposition. The pattern of preferential colonisation suggested that plant detritus represented a primary food source for invertebrates and not simply a refuge. Colonisation was found to be a function of the stage of decomposition, regardless of plant species. The lower temporal availability of willow leaves compared to the native evergreen tree leaves appears to be insufficient to enhance the production of the benthic macroinvertebrates.

The existence of allometric relationships between home-range size and body mass was tested for 34 Italian mammals and 106 Italian birds. These allometries were investigated in relation to a carnivorous, omnivorous or herbivorous diet and, in the case of birds, also territoriality. Initially, non-phylogenetic comparative analyses were undertaken by fitting general linear models to data on average home-range size and average body mass obtained from the literature. Then, two phylogenetic trees for the studied species of mammals and birds were reconstructed and phylogenetic independent contrasts were applied in order to determine the influence of phylogeny on these relationships. For mammals, the type of diet proved to be a determining factor in defining the relationship between home-range size and body mass. Significant allometries were found with both conventional and phylogenetic analyses in all trophic groups. The results emphasized the importance of the spatial distribution of resources in understanding these allometries. For birds, conventional analysis showed significant relationships between home-range size and body mass, and pointed to the importance of both diet and territorial systems in understanding these allometries. After controlling for phylogeny, significant allometries were found only for those birds for which information on the size of their feeding territory was available. Regardless of the complexity of factors influencing the home-range size of a species, the outcomes of this study support the notion of the existence of an allometry between home-range size and body mass among Italian mammals and birds, suggesting that further developments of this area of investigation may prove worthwhile