Freshwater influences on hydrology and seagrass dynamics of intermittent estuaries

Over a three-year period, impacts of changed flow regimes in small western-Victorian estuaries with Mediterranean climates were investigated. Ecosystems with artificially increased and reduced freshwater inflows were compared using a whole-system, process-based approach. Studies on such systms are rare despite their vulnerability and ecological importance.

Resource heterogeneity for stream detritivores

Invertebrate animals in headwater streams depend upon leaves, wood and bark for both food and living space. This project demonstrated the strength of that dependence where the patchiness in habitat is influenced at the smallest spatial scales by the movement of sediments, and at the largest by agricultural clearing.

Fish use of flooded margins of an intermittently open estuary

Fish communities in the shallow flooded margins of an intermittently open estuary were examined over an 18 month period. A distinct shift in the fish assemblage occurred when the mouth of the estuary closed and was associated with changes in the hydro-period, food availability and physico-chemical changes in the main channel.

Hydrodynamics, nutrients and algae of Fitzroy and Merri River estuaries

Various physical, biological and chemical attributes were investigated for the Fitzroy and Merri River estuaries. This research found algal communities were most influenced by high nitrogen concentrations at times of low flow. Mangement of nutrients within each catchment is therefore of high importance to reduce the possibility of future blooms.

Effects of Phytophthora cinnamomi on heathland fauna and ecosystem function

Progression of disease caused by the plant pathogen Phytophthora cinnamomi was correlated to rainfall events and resulted in a loss of plant species diversity in heathland vegetation at Anglesea, Victoria. Lower captures of small mammals were recorded in diseased areas. Management of disease using the chemical phosphite was also evaluated.

Water regime and salinity changes in wetland macroinvertebrate communities

The research successfully showed how biological communities change in wetlands that are affected by salinity and altered water regimes as a result of irrigation and river regulation. As an outcome of the study, recommendations have been made for the future management of wetlands in the Kerang region in northern Victoria.

Landscape pattern, countryside heterogeneity and bird conservation in agricultural environments

This study confirms the valuable contribution that agricultural landscapes make to bird conservation in Australia. While native vegetation is critical to conservation efforts, careful management of production land-use types may provide additional benefits. Results show that productive farm enterprises can make real contributions to the success of broader conservation goals.

Acid drainage, limnology and bioremediation of western Victorian coal mine lakes

Rehabilitation of Alcoa's Anglesea open cut brown coal mine to a healthy lake has many environmental challenges. The study of regional acid drainage, limnology of Wenslydale Coal Mine Lake and passive bioremediation of acid mine water has shown that a healthy lake can be created.

Spatial and temporal variation of infauna in an Australian estuary

Macroinvertebrates living within the sediments of the Hopkins River estuary were examined during 1997. Differences in the abundance and composition of faunal assemblages were identified between vegetated and unvegetated habitats and between the lower, middle and upper sections of the estuary. The numbers of taxa and individuals present were found to be similar to that of other periodically opened estuaries.

Flow patterns affect leaf processing by invertebrates in temperate streams

This work qualified how stream hydraulics affect leaf accumulation habitats used by stream-dwelling insects and the speed at which leaves decompose as a consequence of the species and numbers of insects that live within leaf packs. Leaf accumulations decompose faster in slower moving water because they attract more insects.

Urbanisation and the ecology of powerful owls ninox strenua in outer Melbourne, Victoria

Historically, the Powerful Owl (Ninox strenua) has been seen as a southeastern Australian species restricted to, or most numerous in, dense gullies of tall open forests in hilly or mountainous areas of the coast and Great Divide. However, recent research has revealed that Powerful Owls may breed numerously and successfully in a wider range of habitats than previously believed, including the forests and woodlands within the metropolitan areas of some major cities.Here we report on the breeding of a number of pairs of Powerful Owls in the Yarra Valley, Victoria. Study sites ranged from relatively undisturbed, wet sclerophyll forest 80 km from central Melbourne, through dry sclerophyll, eucalypt-dominated open forest with some disturbance, to a highly disturbed urban parkland only 18 km from central Melbourne. We found that Powerful Owls breed successfully in some urban areas, but are limited in the amount of human disturbance they can tolerate near their nesting hollow. In the most heavily utilized section of the urban parkland, all breeding attempts were unsuccessful and in one year the young were apparently eaten by one of the parents. This followed construction of a timber boardwalk under the nest tree during the breeding season. The Powerful Owls subsequently moved to a more secluded nesting hollow and raised two young. Recommendations for management of Powerful Owls in urban areas are discussed in the context
of these results.

Effects of fragmented habitat and fire on the distribution and ecology of the swamp antechinus (Antechinus minimus maritimus) in the Eastern Otways, Victoria

This study investigated the distribution, habitat and population dynamics of the swamp antechinus (Antechinus minimus maritimus) in the eastern Otway Ranges. The species has a restricted, disjunct distribution and has been recorded at 25 sites between 1969 and 1999. All sites were located within 7 km of the coast, occurred at altitudes up to 80 m above sea level and within 10 m of a gully. Analysis of landscape site variables identified sun index as being significant in determination of the probability of occurrence of A. minimus. The presence of A. minimus is negatively associated with sun index, occuring at sites that have a southerly aspect and gentle slope. A. minimus was located in a range of structural vegetation including Open Forest, Low Woodland, Shrubland and Hummock Grassland and a number of floristic groups, some characterised by high frequencies of sclerophyll shrubs, others by high frequencies of Pteridium esculentum, hummock grasses and herbaceous species. A. minimus occurs in fragmented, small populations with maximum population densities of 1.1–18 ha^–1. Populations at inland sites became extinct after the 1983 wildfire which burnt 41 000 ha. These sites have not been recolonised since, while on the coast the species did not re-establish until 1993–97. One population that is restricted to a narrow coastal strip of habitat is characterised by high levels of transient animals. The species is subject to extinction in the region due to habitat fragmentation, coastal developments and fire. Management actions to secure the present populations and ensure long-term survival of the species in the area are required and include implementation of appropriate fire regimes, prevention of habitat fragmentation, revegetation of habitat, and establishment of corridor habitat.

The distribution and ecology of the Rufous Bristlebird (Dasyornis broadbenti) at Aireys Inlet, Victoria

A study to assess distribution, numbers and habitat of the Rufous Bristlebird was conducted during 1997 and 1998 along the coast at Aireys Inlet, Victoria. Monthly surveys were conducted along selected pathways for 1 h at sunrise, noon and late afternoon. Birds were recorded on the basis of sightings and calls; 75% of records were from calls. The number of records of birds for April–June was significantly lower than for January–March, July–September and October–December. There was no difference in frequency of records due to weather conditions (clear, overcast or rain), presence of wind or difference in temperature. The Rufous Bristlebird inhabited remnant coastal vegetation, but also utilised nearby house gardens and road verges. Birds appeared to occupy distinct territories, with each separate territory occuring along a narrow strip of land on the coastal cliffs. The number of territories identified ranged from 14 to 33. Territories were occupied predominantly by pairs of birds. The minimum number of birds present was estimated for each survey session and ranged from 2 to 34. A conservative estimate of the bristlebird population in the area, based on the assumption that a territory was occupied by a pair, was thus between 28 and 66. A number of threats to the Rufous Bristlebird were identified in the study area including loss and fragmentation of habitat from housing developments and walking tracks. Introduced predators including foxes, cats and rats have been recorded, but their impact is unknown. The effect of people walking along the tracks and the presence of dogs is unclear.