Thredbo Village is a year round alpine resort located in Kosciusko
National Park, south eastern New South Wales. Treated sewage effluent
from Thredbo Village is discharged to the upper Thredbo River. The
river is a rocky bottomed, high mountain stream (> 1,200 m altitude in
the study area) flowing predominantly through subalpine woodland, the
only major impact on the river within the study area was that of the
Thredbo Village alpine ski resort.
Nutrient concentrations were measured in the upper Thredbo River
monthly from January to September 1983 at 9 sites along the river, both
upstream and downstream of the effluent discharge. In addition,
invertebrates were collected at the same sites in January, April and July
1983.
The near pristine section of the upper Thredbo River upstream of
Thredbo Village was low in phosphorus and nitrogen (<20 mg m-3 and
<100 mg m-3 respectively). The sewage effluent discharge was high in
phosphorus and nitrogen (up to 5,000 mg m-3 and 28,000 mg m-3
respectively). Phosphorus generally returned to concentrations similar to
those measured in the pristine sections by 3.5 kilometres downstream of
the discharge. Nitrogen (mostly in the form of nitrate and nitrite)
often remained elevated down to the most downstream site, 8 kilometres
downstream of the effluent discharge.
The elevated nutrient concentrations immediately downstream of the
effluent discharge stimulated the growth of attached filamentous algae in
January when conditions for growth were most favourable. It is
concluded that this growth provided an additional food source for several
invertebrate taxa, Cricolopus sp. 12E and 160E (Diptera, Chironomidae),
Conoesucidae sp. TR6, Oxyethira columba (Trichoptera), Nais sp.,
Aeolosomatus niveum (Oligochaeta), and Austrocercella tillyardi
(Plecoptera), which occurred in higher numbers downstream of the effluent
discharge. Downstream of the effluent discharge the taxonomic
composition of the invertebrate community was not altered substantially
from that upstream, although there was a significant increase in the
abundance of the taxa which could take advantage of the increased food
resource. The changes in the invertebrate community were not evident
3.5 kilometres downstream of the effluent discharge, which corresponded
to the return of phosphorus concentrations to background levels. There
were increased abundances of several invertebrate taxa downstream of
both Thredbo Village and the rubbish tip in January which were
consistent with, but not as great as, those downstream of the sewage
effluent discharge. This was likely to be a result of increased nutrient
loads from urban runoff and tip leachate at these sites which possibly
lead to increased algal productivity. However, nutrient concentrations at
these sites were not notably higher than at the control site. The
sewage effluent discharge resulted in only small changes to the
invertebrate community in April or July 1983.
| Identifer | oai:union.ndltd.org:ADTP/219396 |
| Date | January 1988 |
| Creators | Tiller, David, n/a |
| Publisher | University of Canberra. Applied Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright David Tiller |
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