Murray, B, Dickman, CR, Robson, TC, Haythornthwaite, A, Cantlay, AJ, Dowsett, NS & Hills, N 2007, 'Effects of exotic plants in native vegetation on species richness and abundance of birds.' in Lunney, D (ed), Pest or guest : the zoology of overabundance, Royal Zoological Society of New South Wales, Mosman, N.S.W, pp. 216-221.
We reviewed published, quantitative studies examining the effects of exotic plants in native vegetation on the species richness and abundance of birds and mammals. We asked whether the incursion of exotic plants into native vegetation has led to consistent declines, increases or no changes in bird and mammal species richness and abundance. Bird species richness and abundance tended not to be lower in sites with exotic plants (exotic sites) compared with sites without exotic plants (native sites). However, there are some reported cases of declines in richness, and declines and increases in abundance of birds in exotic sites. While there is not enough evidence to generate broad patterns in relation to species richness of mammals in exotic sites, abundances of individual mammal species demonstrated idiosyncratic responses (either increases, decreases, or no changes) to the incursion of exotic plants. Any differences observed in species richness and abundance of birds and mammals between exotic and native sites are probably due to habitat modifications by exotic plants resulting in changes to vegetation that is important for foraging, protection, and reproduction of the vertebrates. Importantly, our review found no published, quantitative evidence that the incursion of exotic plants into native vegetation leads to the over-abundance of any bird or mammal species. Nevertheless, the results of our review must be viewed as preliminary findings: there is still much to be done to untangle the complex ecological effects of exotic plants on birds and mammals in native vegetation.
Dowsett, NS & Rayburg, SC 2011, 'Heavy metal distribution in estuarine sediments: a comparison of a seagrass bed and adjacent bare sediment', Balance and Uncertainty Water in a Changing World, Proceedings of the 34th IAHR World Congress, Congress of IAHR, the International Association of Hydro-Environment Engineering and Research, Engineers Australia, Brisbane, pp. 1047-1053.
Seagrasses are highly productive and dynamic ecosystems, which supply a range of ecosystem services. Despite this, seagrass communities are globally in decline, largely due to anthropogenic influences. Urban and agricultural development, coupled with poor land management practices, can result in increased pollutants entering estuaries. Sediments below seagrass beds have been relatively well established as nutrient sinks. However, few studies have looked specifically at the concentration of heavy metals in seagrass bed sediment compared with adjacent bare sediment. This paper presents some preliminary findings for looking into the relationship of heavy metals in seagrass bed sediment compared with adjacent bare sediment within a temperate estuary of eastern Australia. Of the metals and elements tested, aluminium, barium, calcium, chromium, copper, iron, potassium, magnesium, manganese, sulphur and strontium were found in significantly higher concentrations within seagrass bed sediments compared to adjacent bare sediment.