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Issue 112

Old habits die hard
The possibility that placental mammals once inhabited Australia is supported by fossil and DNA evidence. If this is the case, the argument that early marsupials thrived in Australia due to the complete absence of placental competitors loses much of its force. Small, early marsupials may have prevailed because they were pre-adapted to the arid environment that developed in Australia after it separated from Antarctica about 45 million years ago.
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Deepwater sharks dogged by overfishing
Many fish fillets marketed as flake come from a group of small sharks known as dogfish. Catches of dogfish are unregulated, and a lack of adequate catch records means some dogfish species are probably being fished at unsustainable levels. At particular risk are several species of endeavour dogfishes.
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Do spine rings tell tales of regeneration
Researchers are studying the growth rings found in the dorsal spines of six species of dogfish as a possible way of ageing the fish.
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Preserving taxonomy
Since the Australian National Fish Collection's (ANFC) foundation in 1943, some 135,000 finfish specimens representing more than 3,000 species have been collected. The collection is used for taxonomic study of fish. Despite the efforts of taxonomists, there are just too many new species being discovered, and too few taxonomists to describe and classify them all.
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Carp crusades
European carp are widespread in the Murray-Darling Basin and occur in all states and the ACT. They are blamed for many aspects of river and wetland degradation. It is unlikely that carp are responsible for declines in native fish or riverbank erosion, but they do cause turbidity, reduce aquatic vegetation and probably increase the occurrence of algal blooms. Successful carp management will require both control techniques and river rehabilitation. A potential long-term control method, daughterless carp technology, entails altering the genetic make-up of carp so that fewer and fewer females are produced from one generation to the next.
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Hands across the water
In 1994, a study assessed historical water quality information on Moreton Bay and estuaries in the Brisbane, Bremer, Pine and Caboolture Rivers. As a result of this research, a Regional Water Quality Management Strategy was developed for the bay and estuaries. To monitor the success of this strategy, an Ecosystem Health Monitoring Program (EHMP) was implemented.
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Keeping trouble at bay
A scientific study has investigated ecological processes and their interactions in Moreton Bay, Qld, and its estuaries. Marine plants, such as seagrass, phytoplankton, microalgae and mangroves, proved useful indicators of bay and estuary health, as they allowed scientist to trace sources of sewage nitrogen. As well as improving the understanding of ecosystem processes, the scientific tasks helped to identify chemical and biological indicators suitable for an Ecosystem Health Monitoring Program.
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Sourcing sediments
Sediment pollution has caused seagrass beds in Moreton Bay, Qld, to decline. In some areas they have disappeared, along with the black swans, turtles and dugongs that grazed them. Local councils and other members of the Healthy Waterways Partnership hope to reverse this trend - possibly even restore lost seagrass beds - by restoring riverbank and other erosion prone areas. To target this work, researchers have studied where the sediment comes from, how it gets there, and why.
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Fresh measures
Five groups of indicators that provide a broad picture of freshwater ecosystem health have been identified as part of the South-east Queensland Regional Water Quality Management Strategy. The indicators have been used to develop Ecosystem Health Plots, which are used to provide a graphical tool to monitor changes in health over time.
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Managing Pine Rivers
On their journey to Moreton Bay, the north and south arms of Pine River, Qld, traverse an 808 square kilometre catchment supporting a variety of land uses. In 2001, the ecological health and water quality of the river varied from fair to fail. Pine Rivers Shire Council is optimistic about its ability to turn these ratings around. Improvements in ecosystem health are expected over the next 10 years. These initiatives will be coordinated with those of other councils through the Healthy Waterways Partnership.
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Master modellers
A model representing the complex ecosystem of Moreton Bay, Qld, and its catchments has been developed from the many research and monitoring programs conducted as part of the Moreton Bay Study and the Regional Water Quality Management Strategy. The model can be used to create 57 management scenarios.
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Small wonders
In May and June 2001, a series of expeditions explored the insect fauna of the Keep River and Gregory National Park region of the Northern Territory.
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Running with bugs
Macroinvertebrates are used as indicators of river health. 'The Waterbug Book' is a resource to aquatic macroinvertebrates and monitoring the health of rivers and streams. From macroinvertebrates found, the health of the water can then be assessed using the SIGNAL-score system.
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Chicken feed
Rabbits have become a staple diet for wedge-tailed eagles. The eagles face a challenge due to the advent of rabbit calicivirus disease and an associated decline in rabbit numbers. Researchers have found that as rabbit numbers decrease, the eagles' diet changes and breeding rate declines.
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Tolerance to 1080
Some grain-eating birds, such as ducks and corellas, in northern Australia, are less tolerant of the toxin 1080 than expected and may face some potential risk of poisoning if baiting campaigns are not carried out carefully.
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Mossies and malaria
CSIRO researchers have modelled a hypothetical system which could see populations of mosquitoes that transmit malaria replaced by populations that do not. The model hinges on two-theoretical genetic constructs that could be inserted into the mosquito genome.
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Not-so-fearsome fossils
Reptiles are believed to have dominated the large, land, carnivorous fauna of Australia millions of years ago. But a review of fossil reptiles has found that the contention that big, fierce reptiles dominated Australia's terrestrial carnivore niches is exaggerated, if not wrong.
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Burning rubber
Rubber vine has the potential to invade most of northern Australia. Fire is considered the best option for controlling the weed where vine infestations exceed 2,000 plants per hectare. Timing of the fire affects survival of the weed.
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Cat chronicles
By 1890, cats inhabited almost all of mainland Australia. The impact of feral cats on native animals is difficult to determine due to the effects of the introduction of foxes and rabbits and changes in land use practices.
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It pays to count your rabbits
Researchers have looked at the genetics of rabbits in an arid to semi-arid region of Queensland to determine rabbit population structures and the mechanisms responsible for them. The research indicates that the size and structure of rabbit populations should be considered when selecting methods of rabbit control.
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