Observations of the large earth bumblebee, Bombus terrestris (L.), in native vegetation were collated to determine the extent to which this exotic species has invaded Tasmanian native vegetation during the first 9 years after its introduction. The range of B. terrestris now encompasses all of Tasmania's major vegetation types, altitudes from sea level to 1260m a.s.L, and the entire breadth of annual precipitation in the state from more than 3200 mm to less than 600 mm. Observations of workers carrying pollen, together with the presence of large numbers of bumblebees at many localities across this range indicate that colonies are frequently established in native vegetation. Evidence that colonies are often successful was obtained from repeated observations of the species during more than 1 year at particular sites. Unequivocal evidence of colonies was obtained from six National Parks, including four of the five in the Tasmanian Wilderness World Heritage Area (WHA). Indeed, the species has been present in the WHA for at least as long as it has in the city of Hobart, where it was first recorded. In southwestern Tasmania, evidence of colonies was obtained up to 40km from gardens, 61 km from small towns and 93 km from large towns. Hence, contrary to previous suggestions, the species is established in the most remote parts of Tasmania and is not dependent on introduced garden plants. Given their strong record of invasion, it is likely that B. terrestris will form feral populations on the mainland of Australia and in many other parts of the world if introduced. Because of their likely negative impacts on native animals and plants, and potential to enhance seed production in weeds, the spread of bumblebees should be avoided.
Summary
Australia's sub‐Antarctic Macquarie Island is presently undergoing one of the most ambitious vertebrate pest eradication programmes ever undertaken. The anticipated success of this programme will release the island's tundra‐like vegetation from well over a century of grazing and disturbance from House Mouse (Mus musculus), Ship Rat (Rattus rattus) and most significantly European Rabbit (Oryctolagus cuniculus). This study describes results from 30 years of vegetation quadrat monitoring (prior to the most recent and comprehensive pest eradication programme) when lower level pest animal control programmes were underway. Plant species were assigned to one of five distinct functional plant groups: Indigenous short‐lived perennials, Introduced short‐lived perennials, Indigenous perennials rarely grazed by rabbits, Indigenous perennials occasionally grazed by rabbits and Indigenous long‐lived perennials heavily grazed by rabbits, with one species, Agrostis magellanica, analysed as a sixth monospecific group. Results from monthly rabbit counts were used to compare changes in abundance of these six groups under different rabbit populations. It was found that there were three distinct phases of rabbit activity during the study period, indicated by (i) an initial very high count year in 1980–1981, followed by (ii) 20 years of low counts ending in 2001–2002 after which (iii) counts rose to medium/high until the commencement of the eradication programme in 2010–2011. Vegetation composition and progression were distinct for these three rabbit count phases. The first four of the plant functional groups decreased under lower count periods and increased in cover under higher rabbit count periods. Agrostis magellanica appears to respond primarily to interspecies competition and is disadvantaged under extended periods of low rabbit numbers. Indigenous long‐lived perennials heavily grazed by rabbits, which includes the large tussocks and megaherbs, is inversely related to rabbit numbers. During the study period, there has also been an overall decline in plant species richness with average species count per quadrat falling by between 0.6 and 2.7 taxa. This study attempts to address the observed vegetation change from this long‐term monitoring, to discuss other potential contributing factors and to use the results to predict likely future vegetation changes after eradication of vertebrate pests.
Transient, acutely toxic concentrations of pesticides in streams can go undetected by fixed-interval sampling programs. Here we compare temporal patterns in occurrence of current-use pesticides in daily composite samples to those in weekly composite and weekly discrete samples of surface water from 14 small stream sites. Samples were collected over 10-14 weeks at 7 stream sites in each of the Midwestern and Southeastern United States. Samples were analyzed for over 200 pesticides and degradates by direct aqueous injection liquid chromatography with tandem mass spectrometry. Nearly 2 and 3 times as many unique pesticides were detected in daily samples as in weekly composite and weekly discrete samples, respectively. Based on exceedances of acuteinvertebrate benchmarks (AIB) and(or) a Pesticide Toxicity Index (PTI) N1, potential acute-invertebrate toxicity was predicted at 11 of 14 sites from the results for daily composite samples, but was predicted for only 3 sites from weekly composites and for no sites from weekly discrete samples. Insecticides were responsible for most of the potential invertebrate toxicity, occurred transiently, and frequently were missed by the weekly discrete and composite samples. The number of days with benthic-invertebrate PTI ≥0.1 in daily composite samples was inversely related to Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness at the sites. The results of
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