Differences in anti-predator traits of a native bivalve following invasion by a habitat-forming seaweed

2012 ◽  
Vol 63 (3) ◽  
pp. 246 ◽  
Author(s):  
Jeffrey T. Wright ◽  
James E. Byers ◽  
Loni P. Koukoumaftsis ◽  
Paul E. Gribben

Invasive habitat-forming species cause large changes to the abiotic environment, which may lead to lethal and sublethal effects on native fauna. In this study, we tested whether morphological anti-predator traits of an infaunal bivalve, Anadara trapezia, differed between areas invaded by the habitat-forming seaweed Caulerpa taxifolia and uninvaded habitats in estuaries in New South Wales, Australia. Caulerpa changes the abiotic environment in ways that may affect traits of native species. In particular, there is lower water flow, lower dissolved oxygen in the water and sediments are more silty and anoxic than in unvegetated habitat. To test our hypotheses, we collected Anadara from Caulerpa and uninvaded habitats and measured shell thickness, shell strength and resistance to opening of valves. We found that all three traits were reduced in Anadara from Caulerpa habitat compared with Anadara from uninvaded habitats. These findings are consistent with the idea that trait modifications in native fauna in response to invasive habitat-forming species can potentially increase susceptibility to predation.

2007 ◽  
Vol 58 (3) ◽  
pp. 263 ◽  
Author(s):  
Jeffrey T. Wright ◽  
Louise A. McKenzie ◽  
Paul E. Gribben

Caulerpa taxifolia is a fast-spreading invasive seaweed that threatens biodiversity in temperate Australian estuaries. To date, little is known about its effects on infauna. In the present study, we describe variation in demographic and life-history traits of the abundant infaunal bivalve, Anadara trapezia, in C. taxifolia and uninvaded habitats (seagrass and unvegetated sediments) at multiple sites across three estuaries in south-eastern New South Wales. Densities of A. trapezia were always lower in C. taxifolia than on unvegetated sediment, and lower in C. taxifolia than in seagrass at three out of four sites where they were compared. Dry tissue weight of A. trapezia was also lower in C. taxifolia than on unvegetated sediment at most sites, but was only lower in C. taxifolia than in seagrass at one of four sites. Populations were dominated by larger individuals (>45 mm length), but smaller individuals (35–45 mm length) were more common in C. taxifolia and seagrass. A. trapezia shell weight and morphology was variable and appeared weakly affected by invasion. Generally, our findings are consistent with the hypothesis that A. trapezia is negatively affected by C. taxifolia. However, C. taxifolia invasion appears complex and, at some places, its effects may not differ from those of native seagrass. There is a need for manipulative studies to understand the mechanisms underlying the effects of C. taxifolia on infauna.


1994 ◽  
Vol 17 (1) ◽  
pp. 19
Author(s):  
J. Barker ◽  
D. Lunney ◽  
T. Bubela

Mammal surveys were carried out on the Carrai Plateau and Richmond Range in north-east New South Wales between March 1988 and November 1989. The emphasis was placed on rainforest mammals, following the recognition by Adam ( 1987) that the species lists of mammals in the state's rainforests were incomplete and that more research was needed. The mammals were surveyed primarily by analysis of prey remains in Dog and Fox scats, collected from roads throughout the forests, and from bat trapping. The bat fauna at both the Carrai Plateau and Richmond Range is rich (1 0 species and nine species respectively, including the rare Golden-tipped Bat, Kerivoula papuensis, in the Richmond Range). Scat analysis revealed the presence of 24 native species on the Carrai Plateau, and on the Richmond Range there were 17 species, including high numbers of two pademelon species. Feral prey species are almost completely absent, although the Fox is an established predator in both areas. A sharp division was identified between the mammal faunas of closed and open forests. Differences were found also between the mammal fauna composition of the two rainforest sites, and with those of nearby eucalypt forests. The mammal fauna of New South Wales rainforests is distinct from open forests and future mammal surveys are needed to ensure an adequate level of knowledge to identify and conserve these areas.


1995 ◽  
Vol 2 (3) ◽  
pp. 299 ◽  
Author(s):  
E. M. Date ◽  
H. F. Recher ◽  
H. A. Ford ◽  
D. A. Stewart

A survey of conservation reserves, rainforest remnants and agricultural districts in northeastern New South Wales was conducted to determine the abundance, movements and habitat requirements of rainforest pigeons, to evaluate the extent and use of suitable habitat in conservation reserves, and to provide guidelines for the conservation and management of rainforest pigeons. Eight species of rainforest pigeon occur in northeastern New South Wales. Commencing with the clearing of rainforest in the 1860s for agriculture, rainforest pigeons declined in abundance throughout New South Wales and by the 1970s five species were thought to be threatened in the state. Since then, rainforest pigeons have apparently increased in abundance and distribution, but the Wompoo, Rose-crowned and Superb Pigeons continue to be listed by the New South Wales National Parks and Wildlife Service as vulnerable and rare. However, populations of all species of rainforest pigeons in New South Wales are relatively small and vulnerable to further loss of habitat. Most rainforest pigeons show a preference for subtropical rainforest habitat, but moist eucalypt forests, gardens and weedy exotic vegetation along roads and on abandoned farmland are also frequented to varying degrees by different species. To investigate recent trends in pigeon abundance we used data collected for up to 12 years from eight sites and during 1988, 1989 and 1990 from 17 rainforest remnants in northeastern New South Wales. The data suggest that rainforest pigeons now occur more frequently in lowland agricultural areas than in the recent past and tend to confirm an increase in abundance since the 1970s. Nesting and foraging habitats for rainforest pigeons are extensive in the conservation reserve system of northeastern New South Wales, but these habitats, which are largely at high elevations, lack winter food resources. Instead, pigeons congregate in remnant rainforest and exotic berry-bearing trees and shrubs in agricultural areas at lower elevations and near the coast. They rely on these habitats for food during winter and it is the restricted extent of this habitat that probably limits their abundance, not the area or quality of habitat at higher elevations. The conservation and management of rainforest pigeons requires the protection of low elevation and coastal rainforest remnants. As development of northeastern New South Wales proceeds, to avoid a decline in the abundances of rainforest pigeons it will be necessary to protect sclerophyll forest with native or exotic fruit bearing trees and shrubs and to extend the area of suitable habitat by the regeneration of rainforest and by the planting of native species used by pigeons as a food source. This will become increasingly important as the control and removal of exotic plants, such as Lantana Lantana camara and Camphor Laurel Cinnamonum camphora, on which some pigeons depend as a winter food source, becomes more successful.


1980 ◽  
Vol 2 (1) ◽  
pp. 31 ◽  
Author(s):  
EJ Weston ◽  
DF Thompson ◽  
BJ Scott

Poplar box (Eucalyptus populnee) woodlands mainly occuron duplex, clay and red earth soils between the 300 mm and 750 mm rainfall isohyets. The poplar box lands have been occupied for from 100 to 150 years and have been modified extensively through tree felling, ringbarking, clearing, cultivation, burning and grazing by domestic livestock. The current land use is described for six vegetation groups which together comprise the poplar box lands. The eastern areas of the poplar box lands are mainly used for intensive agriculture based on wheat. barley and grain sorghum, with small areas sown to c~ops of high water demand. Mixed farming involves dairying (in Queensland) and fat lambs (in New South Wales) and broad-acre cereal and fodder cropping. Sheep and cattle grazing replace intensive crop production as the rainfall decreases. In all areas used for cropping the stability and fertility of the soil are of paramount importance in maintainihg production. The use of woodlands in areas of lower rainfall can lead to deterioration of the resource and to the encroachment of woody native species into the grazing lands. Because cropping is unreliable the opportunity to use cultivation to control woody regrowth is reduced. In central areas much of the land can be sown to improved pastures, but in western areas diversification is limited by the low rainfall and land use is restricted to grazing, initially only by sheep but now by sheep and cattle. Particularly in western New South Wales the increase in unpalatable shrubs and the decrease in available forage has resulted in low stocking rates, and high grazing pressure, making reclamation and pasture improvement difficult. In consequence many enterprises are becoming uneconomic.


2019 ◽  
Vol 67 (7) ◽  
pp. 510 ◽  
Author(s):  
Justin S. H. Wan ◽  
Keith L. McDougall ◽  
Edward C. Y. Liew

In Australia disease caused by Phytophthora cinnamomi can have devastating impacts on native vegetation, especially on plant species with restricted distributions. The identification of susceptible threatened species is a crucial first step in understanding disease aetiology and selecting appropriate management. In a glasshouse trial, plants of 16 rare and threatened New South Wales native species from 10 families were inoculated with the pathogen. Phebalium squamulosum spp. alpinum was included as a susceptible control. We found that three species are highly susceptible to the pathogen (Nematolepis rhytidophylla (Albr. & N.G.Walsh) Paul G.Wilson, Prostanthera marifolia R.Br., Pultenaea sp. ‘Genowlan Point’); four others (Hibbertia spanantha Toelken & A.F.Rob, Phebalium bifidum P.H.Weston & M.J.Turton, Plinthanthesis rodwayi (C.E.Hubb.) S.T.Blake, Pomaderris delicata N.G.Walsh & Coates) are likely to be susceptible based on symptoms. The remaining species had few or no plant deaths and no pathogen recovery from the roots. All of the species regarded as highly susceptible are known from single populations. Following these results, subsequent research will assess the efficacy of prophylactic treatment on highly susceptible threatened species, and test whether glasshouse tests are indicative of field responses. Other threatened species will also be tested for susceptibility.


2001 ◽  
Vol 23 (2) ◽  
pp. 159 ◽  
Author(s):  
D. T. Vere ◽  
R. E. Jones ◽  
M. H. Campbell

Pastures are the basis of most forms of agricultural production on the New South Wales central and southern tablelands. Pastures occupy the bulk of the region's landmass and pasture-based livestock production annually contributes more than three-quarters of the regional gross value of rural production. Throughout the region, there is substantial variation in pasture composition, ranging from high quality introduced perennial grasses and legumes to pastures comprising mainly low quality native species. This paper examines the economics of the main categories of temperate pastures over a range of soil fertility-rainfall environments on the south-eastern tablelands areas of New South Wales. Using a linear programming model and discounted development budgets, the results demonstrate the strong influence of the environment on the economics of the individual pasture systems. The highest economic returns in both the short and longer-terms were to the introduced perennial grass pastures in most of the environments. Pastures based on introduced legumes and the high quality native species also generated sound economic returns, although there are recognised problems with the persistence of the legume pastures. Over time, the returns to the better quality native pastures compare favourably with the introduced legumes and are better suited to acidic soils than the perennial grasses. Low quality native species produced relatively poor economic returns in all environments and unfortunately, are the main pasture type in the region's less favourable environments.


2004 ◽  
Vol 10 (3) ◽  
pp. 180 ◽  
Author(s):  
DR. Cilla Kinross

Many windbreaks are being planted on the Tablelands of New South Wales, Australia to provide shelter for stock and crops, but little is known of the effect of these linear plantations on the regional bird community. This paper compares the avian diversity, density and species composition in a range of habitats in agricultural landscapes, including farm windbreaks, and draws conclusions as to the benefits of windbreaks to bird conservation. The data were collected between 1993 and 1997 with 12 visits to each of 84 sites, placed a priori into seven habitat types on six grazing properties in the Tablelands of New South Wales, Australia and analysed using ANOVA and canonical variate analysis to identify bird-habitat relationships and patterns. Species diversity and density were found to be highest in remnant woodland and lowest in grassland, but differences between other habitats were less robust. Windbreaks >19 m wide were closer in diversity and species composition to remnant woodland than windbreaks =15 m wide. Of the 105 bird species observed, 17 were confined to remnant woodland and 67 native species were observed using planted sites. These species were not, as had been predicted, entirely composed of generalist-opportunistic species, but, particularly in the wider planted sites, included several woodland species identified as declining in this region. Although clearly not as important as remnant woodland, farm windbreaks, shelterbelts and woodlots of suitable size and composition appear to contribute significantly to avian diversity in agricultural areas and their planting should be encouraged and supported by the rural community and government.


1998 ◽  
Vol 25 (1) ◽  
pp. 23 ◽  
Author(s):  
G. S. Baxter ◽  
P. G. Fairweather

Food supply is commonly regarded as ultimately controlling the size of bird colonies. Most studies examining this problem have been on seabirds, and all in the Northern Hemisphere. To search more widely for evidence of the importance of food as a factor controlling the size of bird colonies, we investigated egret colonies in a Southern Hemisphere region. We examined the relationship between colony size and the area of potential feeding habitat around each colony, compared with variables associated with the location and the physical characteristics of each colony. All colonies (13 in total) along 800 km of coastline in New South Wales, Australia, were studied. Colony size ranged from 7 to more than 2000 nests. There were very few correlations between the number of nests and the areas of different types of feeding habitat within 20 km of colonies. However, the available area of saltmarshes proved to be a significant predictor of colony size for great (Ardea alba), intermediate (A. intermedia) and little egrets (Egretta garzetta). Saltmarshes may be stable, long-term feeding habitats for these three native ‘aquatic feeders’, but not for the terrestrially feeding cattle egret (Ardea ibis). Nest numbers of this latter species were related positively to the area of saltmarshes, and negatively to latitude, suggesting that nest numbers of this exotic species may be influenced by climate, with proximate factors such as colonial nesting with the three native species also being important. Because of the numerical dominance of cattle egrets, the numbers of nests of all species followed the same pattern as that for cattle egrets.


1986 ◽  
Vol 13 (2) ◽  
pp. 141 ◽  
Author(s):  
JD Robertshaw ◽  
RH Harden

Prey selection and its effect on the major prey species was examined between 1979 and 1980 by comparing the diet of dingoes and the biology of the swamp wallaby at two sites where the relative numbers of dingoes and wallabies differed. Selection of prey by dingoes was not opportunistic but demonstrated a preference for larger native species, and was similar to that found in the same area between 1972 and 1974. In particular, dingoes had a strong preference for swamp wallaby, the occurrence of which in the diet was disproportionate to its observed numbers; and switching was not observed even when numbers of swamp wallaby were reduced and alternative macropod prey present. Contrary to Optimal Foraging Theory predictions that the predator should become more catholic in prey selection, this species was more frequent in the diet when its availability was lower. At one site the major effect of this predation was the disruption of the breeding cycle, as a result of the loss of large pouch young because of the harassment of their mothers.


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