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THE FAUNA OF LAKE PEDDER - CHANGES AFTER THE FLOODING AND THOUGHTS ON RESTORATION

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Lake Pedder - Values and Restoration: 2001
THE FAUNA OF LAKE PEDDER - CHANGES AFTER THE
FLOODING AND THOUGHTS ON RESTORATION.
P.S. Lake
1
LAKE, P.S., 2001: The fauna of Lake Pedder - Changes after the flooding and thoughts on restoration; in:
Sharples, C., (ed.), Lake Pedder: Values and Restoration, Occasional Paper No. 27, Centre for
Environmental Studies, University of Tasmania, p. 87 - 98.
Lake Pedder was remarkable for its setting, its unique quartzitic sand beach and its fauna. Its high biological
value was not realised until the scheme for flooding became entrenched. From 1975 to 1989 twelve sites around
the Huon - Serpentine Impoundment ("Lake Pedder") were regularly sampled. Four species of endemic animals
have disappeared and five species peculiar to the lakes (Lake Pedder and Lake Edgar) have also disappeared.
During the survey 73 faunal species were collected. Faunal abundance, dominated by the trichopteran Notalina
parkeri, peaked in 1977 and then steadily declined to low levels. If restoration is to be carried out, problems to
deal with include erosion and plant colonisation of the exposed shores and the control of trout. The original
beach appears to be intact. With careful planning, Lake Pedder is restorable.
Key Words: Australia, Tasmania, Lake Pedder, freshwater invertebrates, species loss, fauna, flooding,
restoration
INTRODUCTION
As many have expressed eloquently in print and in
images, the original Lake Pedder with the confluent
Lake Maria was a very beautiful lake in a
dramatically inspiring setting. There were many
moods of the lake from the balmy stillness of
autumn to the swirling cold storms of any time of
the year. To many the lake was the natural
centrepiece, the symbol of sanctity, of the south-
west wilderness:- destroy it and the wilderness
shrinks. The beach of Lake Pedder was famous for
its great size, its beautiful symmetry, its stark
pinkish white sand and its very marked seasonal
changes in water level - being inundated in winter
and spring and uncovered in summer. Behind the
beach were tea tree-covered dunes and behind the
dunes were the swamps, pools, lagoon and slow
flowing channels and creek of the Lake Maria-
Maria Creek system. Away to the south-east by
about 12 km on the eastern margins of the Huon
Plains was the shallow and small Lake Edgar
(surface area = 0.8 km
2
); a sheltered lake with
extensive beds of reeds and sedges (Knott & Lake
1974). All of these lakes contained acidic waters
low in conductivity and darkly coloured with
dissolved humic materials (Buckney & Tyler
1973).
These lakes, the Huon and Serpentine river valleys
and the extensive areas of buttongrass plains and
heath of the Huon Plains were all inundated in
1973-74 by the impounded waters of the Middle
Gordon Hydro-Electric Power Scheme. Almost it
seems as a gesture of repentant propaganda, the
new impoundment, "the enlargement of Lake
Pedder", was called Lake Pedder, even though it
bore little resemblance to the original lake and
flooded two other lake systems as well; an
unofficial name for the new Lake Pedder is the
Huon-Serpentine Impoundment. In discussing the
fauna of the original Lake Pedder I will also be
dealing with the fauna of Lake Maria, Lake Edgar
and fleetingly the Huon Plains and buttongrass
plains around Lake Pedder.
1
Professor in Ecology and Program Leader,
Cooperative Research Centre for Freshwater Ecology,
Department of Biological Sciences, Monash University,
Clayton, Victoria
THE BIOLOGICAL VALUES OF THE
LAKE PEDDER AND LAKE EDGAR
AREAS
As related in the Final Report of the Lake Pedder
Committee of Enquiry (1974), the scientific and
ecological values of Lake Pedder were not
recognised in the official surveys of the lake
(Hydro-Electric Commission 1967); even though
two fish species, one being the endemic Galaxias
pedderensis, had been collected and described
(Frankenberg 1968). Then steadily, through the
unofficial and frugally funded efforts of scientists
(mostly biologists) such as Ian Bayly, Bill
Williams, Roy Swain, Bill Wilson, John Hickman,
Arturs Neboiss, Peter Tyler, Brenton Knott, and
Jim Peterson, by 1970-71 it became obvious that
the Lake Pedder/Lake Maria system was an
ecologically valuable if not unique ecosystem.
Further it became clear that this ecosystem, with its
acidic, darkly coloured and humic waters of low
conductivity (Buckney & Tyler 1973), harboured a
set of distinctive faunal communities - zooplankton,
nekton, benthos and psammon - the integrity of all
87
Lake: Aquatic Fauna
of which was threatened by flooding (Bayly 1965,
1973, Bayly et al. 1966, 1972, Swain 1972, Lake
Pedder Committee of Enquiry 1974). The unique
psammon community of the Lake Pedder beach
was dominated by an abundant phreatoicid isopod,
Uramphisopus sp. 1 (see Knott 1975), which
formed characteristic trails in the fine pale pink
sand (Bayly et al. 1972, Bayly 1973). The endemic
fish G. pedderensis, and the water bug
Diaprepocoris pedderensis were part of the nekton.
By 1974, it was suggested that Lake Pedder/Lake
Maria harboured 13 endemic species of animals
along with 3 species of rare animals for which "the
Lake Pedder area provided the most important, or
one of the most important, habitats" (Lake Pedder
Committee of Enquiry 1974).
In a separate survey the shallow dystrophic Lake
Edgar with its macrophyte beds was found to
harbour an abundant invertebrate fauna (47 taxa).
An unpigmented phreatoicid isopod found only in
Lake Maria and Lake Edgar was moderately
common (Knott & Lake 1974, Knott 1975). In
crayfish burrows and bogholes of the buttongrass
plains of the Huon Plains and McPartlan Pass, two
species of syncarid crustaceans, Allanaspides
helonomus (Swain et al. 1970) and Allanaspides
hickmani (Swain et al. 1971) were found. The
peculiar community of animals dwelling in the
water of the crayfish burrows was subsequently
termed pholeteros
(Lake 1977).
THE ENDEMIC AND DISTINCTIVE FAUNA
Over the years through taxonomic studies (eg.,
Pinder & Brinkhurst 1989, StClair 1994) and
through extensive collecting in south-west
Tasmania (e.g., Chilcott 1988 a & b, Neboiss et al.
1989), the lists of endemic animals and of fauna
peculiar to Lake Pedder have steadily changed.
Currently five species of invertebrates and 1
species of fish are regarded as endemic to the Lake
Pedder area (Table 1), whereas 8 species of
invertebrates and 1 species of fish are identified as
taxa for which the Lake Pedder area was an
important habitat (Table 2).
THE FLOODING OF THE LAKE PEDDER
AREA.
In late 1972 the inundation of Lake Pedder began
amid much outcry and protest. In early 1973 the
new Federal Minister for Environment, Moss Cass,
visited the lake seeing the last of the lakeside
protesters camped on the top of the dunes. During
its filling I remember on several trips, including
one with P.Tyler, being worried by the extent of
wave erosion along the new shores and by the
undercutting of steep slopes. By 1974 following the
rejection of the findings of the Lake Pedder
Committee of Enquiry the fate of the lake and its
Platyhelminthes
Tricladida Romankenkius pedderensis
Crustacea
Isopoda Phreatoicidae Uramphisopus sp. 1
Uramphisopus sp. 2
Insecta
Trichoptera Kokiriidae Taskiria mccubbini
Taskiropsyche lacustris
Pisces
Galaxiidae Galaxias pedderensis
Table 1: Animal species endemic to the original Lake Pedder system.
Annelida
Oligochaeta Tubificidae Telmatodrilus pectinatus
Crustacea
Copepoda Centropagidae Calamoecia australis
Syncarida Anaspididae Allanaspides helonomus
Allanaspides hickmani
Insecta
Hemiptera Corixidae Diaprepocoris pedderensis
Trichoptera Limnephilidae Archeophylax vernalis
Leptoceridae Westriplectes pedderensis
Mollusca
Gastropoda Hydrobiidae Glacidorbis pedderi
Pisces
Galaxiidae Galaxias parvus
Table 2:
Species for which the Lake Pedder basin provided an important habitat.
88
Lake Pedder - Values and Restoration: 2001
surrounds was sealed. One recommendation never
acted upon was that:
"funds be set aside for an urgent and
intensive program of investigations to
determine the possibilities of natural or
artificial re-establishment of the species in
the new environment of the enlarged
impoundment and to suggest management
strategies by which this might best be
encouraged; to undertake a comprehensive
long-term monitoring program to ascertain
the extent to which the re-establishment is
taking place".
Throughout the campaign to save the lake the
protesting biologists had been told that our
concerns for the fauna were misplaced and that the
fauna of the lake would simply migrate up to the
new shores. Indeed in places around the new
shores, beaches were cut by the HEC through the
peat to the underlying gravel .
The biologists’ claims were also regarded as
exaggerated. Judging the paper by Bayly et al.
(1972) as an Environmental Impact Statement, an
environmental consultant (Spry 1976) wrote:
"examples of exaggerated impacts by
conservationists are probably just as
common as obscured or diminished impacts
by developers. Assessment of impacts as
being exaggerated is a subjective matter and
unequivocal examples are not easy to find. I
would offer the alleged detrimental impacts
of the flooding of Lake Pedder on the flora
and fauna (Bayly et al. 1972) as an
example".
THE INITIATION OF THE MONITORING
PROGRAM
Thus the biota and ecosystem of the area to be
flooded were regarded by many aquatic biologists
as being of very high scientific value in spite of the
suggestions that such claims were seen by some as
being exaggerated. In Australia over the years
many large impoundments have been built, yet in
no case after filling has the benthos been monitored
regularly. Spurred on by these two considerations I
decided to monitor the littoral benthos of the new
impoundment. In this endeavour I was greatly
assisted by many colleagues to whom I am very
grateful; in particular from the University of
Tasmania great help was given by Ron Mawbey,
Roy Swain, Alastair Richardson, Dave Coleman,
Richard Norris and Piers Allbrook, and from the
Inland Fisheries Commission by Robert Sloane; at
Monash University Dave Morton and Alena
Glaister sorted the samples and identified many of
the taxa and Leeanne Matheson helped in the
analysis and in production of the figures. The
Tasmanian National Parks and Wildlife Service and
the Inland Fisheries Commission kindly gave us
permission to take faunal samples.
Our first trip in November 1975, in which only 3
sites were sampled with two small aluminium
runabouts, was a very hazardous pilot study; we
needed a bigger and safer boat that must be ready
for any kind of weather. So we then used Ron
Mawbey’s father’s runabout that provided us with
cold and wet but fast trips between sites. Finally we
graduated to the University of Tasmania’s
comfortable Sharkcat. Twelve sites from near the
Edgar and Scotts Peak Dams (Edgar Bay) to the
Lake Pedder basin (Pedder Reach) were selected
(Figure 1), ranging from sheltered swampy sites
(sites E & J , Figure 2) to very exposed rocky sites
(sites D & G). At each site along the shore we took
four 3-minute sweep samples using standard F.B.A.
long-handled pond nets. The samples were
preliminarily sorted in the field, then preserved and
returned to Monash for sorting, identification and
counting. From 1975 to 1989, we sampled all of
the sites on ten occasions - each time in December.
OBSERVATIONS AND RESULTS OF THE
MONITORING PROGRAM
As stated before, shortly after the lake filled myself
and Peter Tyler went on a trip on the new
impoundment and we saw that wave erosion was
having severe effects on the exposed shores and in
places the erosion had quickly cut through to
bedrock. This potential for erosion was borne in
mind in the overall selection of sites for the
monitoring program. There were four sheltered
swampy sites where the soil/peat was not
progressively eroded and where initially after
flooding there was copious amounts of drowned
vegetation including trees, such as at Site J (Sites E,
F, I and J, Figure 1). This vegetation has steadily
declined with wave action and decomposition
though some of the dead trees have remained. Four
sites were moderately sheltered (Sites B, C, H and
L, Figure 1) with some erosion through the soil to
expose gravel and rocks, and steady and substantial
losses of drowned vegetation. There were four
exposed sites (Sites A, D, G, and K, Figure 1) with
almost complete loss of vegetation with time and
great losses of soil and peat such that rocks,
bedrock outcrops and gravel became the dominant
substrata.
Over the course of the monitoring program, 73
species of littoral macrofauna were collected.
Insects dominated this total with 60 species,
followed by 5 species of water mites, 3 species
of molluscs, 2 species of fish and one each of
crustacean, oligochaete worm and triclad flatworm.
Of the total number of animals collected, the case-
89
Lake: Aquatic Fauna
Figure 1: The distribution of sites where sampling was carried out around the Huon - Serpentine Impoundment.
Figure 2:
A swampy site, Site J, in December, 1975.
90
Lake Pedder - Values and Restoration: 2001
Figure 3: Mean numbers of animals and of the trichopteran Notalina parkeri (± standard deviation) caught per site per trip
between 1975-1989.
building leptocerid trichopteran Notalina parkeri
dominated, comprising 75%, followed by the
amphipod crustacean Austrochiltonia australis at
13%. In the collections made shortly after flooding,
N. parkeri was widespread and very common
(Figure 3), whilst A. australis only occurred at
sites around Edgar Bay and was uncommon. By
1986 A. australis was the dominant animal and
occurred at all sites (Figure 4). In the final
collection of 1989, 51% of the total abundance was
A. australis, followed by 6.5% for N. parkeri and
4.8% of another leptocerid trichopteran
Atriplectides dubius. The phenomenon of a slow
and steady change from insect to non-insect
domination of the fauna of lakes with time is an
interesting and unsolved puzzle for limnologists
(Hutchinson 1993).
In two years from 1975 to 1977, the littoral fauna
underwent a massive increase in abundance, to
peak at a mean total number of 816 animals per
collection per site in 1977 (Figure 3). Steadily from
1977, there was a decline in abundance to reach the
low average of 73 animals per site in 1989. This
phenomenon of a boom in abundance and
production after the filling of dams is well known
(e.g., Zhadin & Gerd 1963, McLachlan 1974,
Armitage 1977) and may be due to increased
production stimulated by an increased input of
nutrients from drowned soil and vegetation (Zhadin
& Gerd 1963, Armitage 1977) and/or to the
provision of an abundant and rich supply of detritus
from the drowned vegetation (McLachlan 1977,
Armitage 1977). In the Huon-Serpentine
Impoundment the influence of increased detritus
may have been particularly important. Nutrients
may have also been released from drowned soil and
decomposing vegetation: in the "boom"
filamentous algae were present on stems of the
drowned vegetation. It was in this period of the
boom in invertebrates that "Lake Pedder" acquired
its reputation as a fishery for large trout. It was also
at this time that our sampling trips coincided with
large hatches of dragonfly nymphs. Nymphs of the
species Hemicordulia tau and Procordulia
jacksonensis would migrate inshore to hatch in
their thousands on the Edgar Dam wall in spring
and early summer and were feasted upon by trout.
Notalina parkeri was always present at most sites
of the impoundment. The amphipod
Austrochiltonia was originally only present at sites
around Edgar Bay; it was collected from Lake
Edgar in 1972 (Knott & Lake 1974). As its
abundance grew so did its distribution until it was
present at all sites by 1989 (Figure 4).
Coincidental with the trend of a boom and decline
in total animal abundance was the abundance
patterns of many species. The unusual, streamlined
water bug, Diaprepocoris pedderensis, was
originally present in low numbers at two swampy
sites. From 1975 to 1979 it increased in range and
abundance (Figure 5) but by 1983 it had
disappeared from the collections. Presumably
populations of this species persist in isolated
91
Lake: Aquatic Fauna
Figure 4:
The changing distribution of the amphipod Austrochiltonia australis between 1975-1989.
92
Lake Pedder - Values and Restoration: 2001
Figure 5:
The changing distribution of the water bug Diaprepocoris pedderensis between 1975-1989.
93
Lake: Aquatic Fauna
Figure 6: Mean number of individuals caught per site per trip (± standard deviation) of the fish Galaxias pedderensis and
Galaxias parvus.
localities in south-west Tasmania. The stonefly
Leptoperla beroe was first collected in low
numbers in the Huon Inlet in 1975; by 1979 it was
fairly common at sites around Huon Inlet, Mount
Solitary and the original Lake Pedder but by 1989
it was rare and confined to 4 sites.
Both the endemic Pedder Galaxias, Galaxias
pedderensis, and the Swamp Galaxias, Galaxias
parvus, underwent dramatic changes in abundance
and distribution. G. parvus was present in
relatively high numbers in 1977 (Figure 6) but in
1978 none of this fish were collected and this
remained the situation. G. pedderensis also peaked
in numbers in 1977 and was subsequently collected
in low numbers until 1980 when it disappeared
from the collections. The causes for the declines in
these two fish appear to be twofold: competition
from, and predation by the introduced Brown
Trout, and competition from the invading Climbing
Galaxias, Galaxias brevipinnis (Hamr 1992 a & b,
Smith & Gilfedder 1993). G. pedderensis is now an
endangered species with no more than 200
individuals believed to exist and is now the subject
of a rescue plan (Hamr 1992 a & b).
The physical changes at the various sites appear to
be reflected in the successional patterns shown by
the littoral fauna. The swamp sites began with a
high abundance of detritivores, principally N.
parkeri, and steadily changed to end with a low
abundance of chironomids by 1989. The very
exposed sites started with low numbers of animals,
mainly N. parkeri, and ended with a relatively high
abundance of amphipods. The moderately sheltered
sites harboured at first a diverse fauna that
subsequently declined in diversity and abundance
to end with assemblages of low abundance
dominated by the amphipods. Needless to say all of
these 1989 endpoints are quite different from the
original fauna of Lake Pedder (Bayly et al. 1966,
1972) and of Lake Edgar (Knott & Lake 1974).
Of the endemic fauna of Lake Pedder only one, the
fish G. pedderensis, was collected in the
monitoring survey, and it has now declined so
much as to be endangered. Given our method of
sampling it is not surprising that the endemic
flatworm was not collected. However it is salutary
to note that not one individual of the two species of
endemic phreatoicid isopods or of the two species
of beach-dwelling kokiriid trichopterans were
collected. Of the animals for which the unflooded
Lake Pedder basin was an important habitat, two
species, the fish G. parvus and the water bug D.
pedderensis, were collected but subsequently
disappeared. However it does appear from recent
sampling (1994) that the original beach of Lake
Pedder is still intact and from this beach,
individuals of the isopod Uramphisopus sp. 1 were
94
Lake Pedder - Values and Restoration: 2001
collected (Tyler et al. 1994). Perhaps remnants of
the psammon community (Bayly 1973) remain.
RESTORATION OF LAKE PEDDER AND
ITS BIOTA.
Whilst Lake Pedder is the centre of attention for
possible restoration, it should be noted that both the
adjoining Lake Maria and the more distant Lake
Edgar should also be considered. In the case of the
latter, lake restoration depends on the way that
water is released from the impoundment; if
impounded waters remain behind the Edgar and
Scotts Peak Dams then this lake will not be
restored.
There is no doubt that attempting to restore Lake
Pedder will be a complex and challenging project.
Part of the difficulty stems from the fact that in
Australia and in the world for that matter, there is
an almost total lack of information and expertise on
the successful restoration of large aquatic
environments. The restoration project if carried out
could be a world first.
If restoration is to be undertaken it will be
necessary as a first step to carry out an extensive
physical and biological survey. The state of the
shoreline, the state of the Lake Pedder beach and
the composition and relative abundance of the biota
in the various communities - benthos (littoral and
offshore), psammon, plankton and nekton - will
need to be accurately assessed. Furthermore such a
survey should be rigorously designed such that it
can serve as a baseline for subsequent monitoring
that should accompany restoration.
From observations of the current impoundment
there are areas, especially in exposed positions with
steep slopes, where wave erosion has been very
substantial. The soil and subsoil have been
removed and quartzitic gravels and rocks have been
exposed. These areas are extensive and need to be
mapped. If restoration of the lake is undertaken
these areas if unattended may be long lasting scars
and will require active physical intervention to heal
them.
From our experience during our monitoring trips
and as is evident in the maps of Peterson & Missen
(1979), in the current impoundment there are
extensive amounts of shallow, very gently sloping,
areas extending out from the shorelines (e.g., off
Site E, Figure 1). A small drop in water level will
uncover many hectares of such shallow areas that
may be visually unattractive and subject to
damaging wind and water erosion. A limiting step
to improving the stability and visual impression of
these areas will be the rate of plant colonisation and
succession. If this is very slow then active
intervention to speed up plant colonisation may be
required.
From the observations of Tyler et al. (1994) it does
appear that the original beach of Lake Pedder is
still intact, even though it may now be covered by a
layer of organic matter. I am sure that this layer
will dissipate as the lake is allowed to return to its
original summer level.
A key matter for successful restoration is the rate at
which the water level is to be dropped. If it was to
be dropped rapidly, a very large, bare and
unattractive area would be exposed. This area
would also be physically unstable and could be
subject to water and wind erosion. Thus to reduce
the creation of a bad visual impact, to reduce
erosion, to allow progressive repair of scarred areas
and to allow successful development of plant cover
in exposed areas, I am strongly of the view that the
level of the impoundment should be dropped
slowly and decrementally.
In terms of restoration of the biotic components of
the original Lake Pedder it is difficult to make
predictions. Clearly the rate and extent of plant
colonisation is a key concern. The original beach of
the lake is intact and the phreatoicids of the original
psammon community are present, and thus some
components of this community may return. The
kokiriid caddis flies of the beach appear to have
been lost.
Of the invertebrates originally present in the Lake
Pedder/Lake Maria system, one of the two
phreatoicid crustaceans is present and may return to
its former abundance (cf. Bayly 1973) with
restoration. For the second species (Uramphisopus
sp. 2) there is the need to survey the bottoms of
Lake Edgar and Lake Maria. Some insect species
such as Diaprepocoris pedderensis and
Archeophylax vernalis are known to have
populations in the area and thus these species may
return. For a species like Westriplectes pedderensis
recolonisation may be difficult as the only known
extant population is on Wilsons Promontory,
Victoria (StClair 1994).
Conversely it is difficult to predict what restoration
may do to those common invertebrates that invaded
the impoundment (e.g., Notalina parkeri ) or were
previously only found in particular localities (e.g.,
Austrochiltonia previously only found in Lake
Edgar). I suspect that many, such as the above two,
are quite adaptable and will persist as dominant
animals.
The restoration of populations of the two fish
species (G. pedderensis and G. parvus) originally
found in Lake Pedder may be difficult. Firstly, the
current status of the fish populations in the
impoundment is uncertain and both species may be
95
Lake: Aquatic Fauna
locally extinct - thus there may not be populations
for recovery, and fish as opposed to insects are
poor colonisers from one isolated water body to
another. Second, the restored lake would contain
high populations of the two invading fish, Salmo
trutta and Galaxias brevipinnis, implicated in the
decline of the two native fish species (Hamr 1992 a
& b). To allow the re-establishment and recovery
of the populations of the original animals that dwelt
in Lake Pedder, it may be necessary to have a
specific program to greatly reduce the numbers of
these fish. As the water level of the impoundment
drops trout populations will become more and more
concentrated and will no doubt have an increasing
impact on their prey populations.
Thus in summary, it may be quite feasible to restore
Lake Pedder and its surrounds. Such restoration
will require careful planning, will need to be
accompanied by regular rigorous monitoring and
will necessitate active rehabilitation efforts. To
restore Lake Pedder will serve as a great symbol to
show that if we put our effort to it, we can bring
back to their former value some parts of the natural
world that we have needlessly destroyed.
ACKNOWLEDGEMENTS.
As indicated in above text, this study would not
have been possible without the generous help of
colleagues in the Department of Zoology,
University of Tasmania and the Department of
Ecology and Evolutionary Biology, Monash
University. I am grateful to both the Tasmanian
Department of Parks, Wildlife and Heritage (now
part of the Department of Primary Industries, Water
& Environment) and the Inland Fisheries
Commission for permission to sample the lake.
This study was supported by funds from the
University of Tasmania, Co-operative Research
Centre for Freshwater Ecology, and Monash
University.
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... Inundation also led to a major change in the available physical habitat and consequently the ecology of the impoundment was altered dramatically (Lake 2001). The release of nutrients from drowned vegetation and peat soils was an important driver for increases in abundances of several elements of the aquatic invertebrate community and the occurrence of filamentous algal blooms (Lake 2001). ...
... Inundation also led to a major change in the available physical habitat and consequently the ecology of the impoundment was altered dramatically (Lake 2001). The release of nutrients from drowned vegetation and peat soils was an important driver for increases in abundances of several elements of the aquatic invertebrate community and the occurrence of filamentous algal blooms (Lake 2001). The development of the impoundment heralded changes in the fish community that was likely responding to changes in trophic structure and habitat. ...
... Recent studies on Tasmanian lacustrine galaxiids have demonstrated the importance of littoral regions of lakes to provide critical habitats for galaxiids, particularly for spawning (Hardie et al. 2006(Hardie et al. , 2007(Hardie et al. , 2011. The inundation of Lake Pedder caused immense changes to the character of the littoral zone (Lake 2001). ...
Article
Full-text available
The Pedder galaxias (Galaxias pedderensis) from Lake Pedder, Tasmania, Australia, is one of the world's most threatened freshwater fish. The flooding of Lake Pedder in 1972 for hydroelectric power generation caused a major change to the ecosystem that initiated an irreversible decline in the Pedder galaxias within its natural range. The flooding inundated another headwater catchment and native and introduced fish from this catchment colonised the impoundment. Numbers of the Pedder galaxias declined markedly as the impoundment matured and as colonising fish proliferated. Surveys in the 1980s confirmed the parlous state of the population, highlighting the need for conservation intervention. Several urgent conservation actions were undertaken to save the species from extinction. Translocation was considered the most important recovery action, given the critically low numbers in the wild. The species is now extinct from its natural range and is known from only two translocated populations. The conservation program, and specifically the translocation recovery action, saved the Pedder galaxias from extinction. The conservation management was extremely challenging since rapidly declining fish numbers needed timely and critical decisions to underpin the future of the fish. Recommendations are provided arising from this case study to guide conservation of freshwater fish in similar circumstances. Journal compilation
... Snorkelling was restricted to depths of less than 1.5 m because tannin in the water caused loss of visibility at greater depths. Snorkeling was conducted at two locations in Lake Pedder; on either side of an isthmus at the southern Swain et al. (1970Swain et al. ( , 1971 and Horwitz (1988Horwitz ( , 1990 and sites surveyed but where no Allanaspides were recorded by Richardson & Swain (1978), Horwitz (1988Horwitz ( , 1990 and Lake (2001). Shaded areas = water bodies. ...
... Sampling in Lake Pedder was confined to the part of the impoundment north of the original Lake Pedder (fig. 1) due to time constraints and because a dozen lakeshore sites to the south of the original Lake Pedder were surveyed from 1975 to 1989 with no Allanaspides recorded (Lake 2001). A total of 28 tows at eight locations around the impoundment ranging in depth from 2-28 m were conducted on the first day. ...
... Two species of phreatoicid crustaceans, one from Lake Pedder (Bayly 1973) and another from Lake Edgar (Knott & Lake 1974), were originally recorded as being in the genus Colubotelson Nicholls, 1944. Subsequent authors also noted these isopods (Lake 2001;Tyler 2001) but as the genus Uramphisopus , based on an overly broad synonymy in an unpublished thesis. Recent revisions of the classification of the Phreatoicidea (Wilson & Keable 2001;Poore et al. 2002) restrict the genus Uramphisopus to the type species U. pearsoni With reference to ecological investigations of invertebrates in the original Lake Pedder, the literature is much more sparse. ...
... Beginning in 1975 and ending in 1989, ten surveys of the enlarged Lake Pedder were conducted in which samples were collected with the aid of sweep nets, although phreatoicideans did not appear in any of those surveys (Lake 2001). Tyler et al. (1994Tyler et al. ( , 1996 report, however, that specimens of a phreatoicidean, identified as a species of Uramphisopus by P. S. Lake and A. Glaister, were retrieved by scuba divers from the still intact, albeit flooded, beach of the original Lake Pedder. ...
Article
Full-text available
The Tasmanian lakes Pedder and Edgar were inundated in 1972 to create a reservoir to feed into a hydroelectric power scheme, despite biologists highlighting the uniqueness of the fauna therein. This fauna included undescribed species of phreatoicidean isopods, which were noted in several subsequent publications but not formally described. In 2010, the original beds of these two lakes were revisited and successfully sampled for these isopods as part of a program to assess the conservation status of the unique fauna of this large freshwater body. These two previously reported species of phreatoicidean are both new to science, distinct from each other and belong to the genus Colubotelson Nicholls, so we provide descriptions and illustrations of these species to assist their identification by other biologists. The two species are easily identified by the shape of the pleotelson and setation of the head, although they are separated by considerably more than two hundred specific differences. C. pedderensis sp. nov. was collected only from the now deeply submerged bed of the original Lake Pedder, whereas C. edgarensis sp. nov. may be found more widely in the current extent of Lake Pedder, owing to its appearance in previously collected samples from the original Lake Pedder as well as in the now drowned area of Lake Edgar. These results bring the known diversity of the family Phreatoicidae in Tasmania to 26 described species, including 16 in the genus Colubotelson. The persistence of phreatoicids in Lake Pedder, despite the extensive changes to its ecosystem, suggests that these two species are more resilient than was suspected.
... For example, damming has been linked to a decline in wetland connectivity and subsequent wetland loss in catchments across Australia (e.g., Barmah-Millewa forest where an estimated 50% reduction in wetland extent has occurred (Lemly et al., 2000) or wetlands becoming permanently connected (e.g., Lake Pedder in Tasmania, Lake, 2001). Although there are significant differences in landscape, ecology, and climate between many of these already modified river systems and those in northern Australia, there are important principles that can be used to support the management of these rivers, underpinned by existing ecohydrological knowledge. ...
Article
Full-text available
Wetlands are one of the most threatened ecosystems on earth. Globally there is growing demand to develop infrastructure to harvest water resources to support agriculture, threatening the ecological integrity of associated wetland ecosystems. We investigated the potential ecological impacts on floodplain wetland connectivity in northern Australia in response to changes in flow regime due to dam construction and climate change. Results for this study indicate that a drier climate and/or dam construction in catchments have the potential to reduce the effective size of the floodplain and reduce wetland connectivity. A drier climate will reduce rainfall and subsequent catchment run‐off, resulting in a decrease in the magnitude of riverine flows. In contrast, dams in the upper catchment will reduce the magnitude of flows downstream. The reduction in flows under both dam development and a drier climate will result in reduced extent and duration of floodplain inundation and decreased wetland connectivity. As a result, we anticipate that this loss of connectivity will reduce the capacity for nutrients, carbon and primary production to be flushed into the river channel, as well as reducing the ability for biota such as fish and turtles to move between in‐channel and off‐channel habitats.
... Peter Lake argues that this initial increase in aquatic faunal numbers after inundation is a well-documented phenomenon, one that may be due to increased organic detritus as a result of the lake bed and surrounding terrestrial areas being disturbed. 29 Drowned vegetation and peat soils contributed to the transformation of the galaxias' environment from one of low productivity to one that was nutrient-rich and more complex, with an increase in aquatic invertebrates and the occurrence of algal blooms. 30 However, as well as transforming the lacustrine habitat, the new impoundment also covered and inundated the Huon River catchment area, where brown trout had been introduced and lived alongside the native climbing galaxias. ...
Article
Full-text available
In 1972 Lake Pedder in south-west Tasmania was submerged under 15 metres of water as a result of the Tasmanian State Government’s Middle Gordon Hydro-electric Power Scheme. The lake was subsumed into a much larger artificial impoundment formed by three rockfill dams, making it the largest freshwater lake in Australia. The Tasmanian government transferred the name Lake Pedder to the new impoundment. Three species endemic to the original Lake Pedder were recorded as extinct as a consequence of the lake’s flooding. The Lake Pedder planarian, a species of carnivorous flatworm, the Lake Pedder earthworm, and the Pedder galaxias, a small freshwater fish, disappeared from the lake area after the inundation of this unique habitat, the site of a number of ecologically valuable faunal communities. The divergent fates of these animals, their status as lost species and their significance as creatures both meaningful and meaning-making, marks out an extinction matrix suggesting that the absence of specific animals and specific experiences and ways of life matter more than others, that specific deaths can be more readily incorporated into stories of loss and restoration, and that the perceived malleability of habitats invariably involves death inscribed as sacrifice or justifiable casualties. This paper seeks to retrieve some of the perspectives and experiences forgotten or written over in the lake’s stories of flooding and redemption.
... Today the Pedder galaxias is considered extinct in what remains of its natural habitat, where introduced brown trout (Salmo trutta) populations and translocated native climbing galaxias, Galaxias brevipinnis (McDowall 2006) now flourish. Some ecologists believe that Lake Pedder and its endemic fauna could be restored if these introduced fish can be suppressed (Lake 2001), however a further imminent threat is the introduced European perch, Perca fluviatilis. ...
... The changes that have occurred in the littoral (shore-line) fauna of the lake since flooding have been documented (Lake 2001). These changes, while significant, suggest that the invertebrate community has become less diverse, with several common species continuing to occur in reasonable numbers. ...
Chapter
Anthropogenic changes to inland waters have significantly affected an estimated >83% of land surface surrounding aquatic systems.
Chapter
Insect conservation is generally a 'young discipline' in Australia and interest has developed mainly since the 1970s. The slightly over 200 years of European settlement of Australia have been associated with massive alterations to natural environments, and rapid changes have enforced impressions of the contrast between modern anthropogenic environments and the more pristine ones that persist. They are associated also with Australia having an unenviably high record of vertebrate extinctions and substantial proportions of extant vertebrates threatened. There is little reason to doubt that invertebrates have also suffered significant losses, but these have not been documented in parallel detail. Extirpations of some butterflies, for example, have been reported intermittently since the late nineteenth century (Waterhouse 1897) but there is no historical record equivalent to the information available in the United Kingdom or United States. © 2012 Springer Science+Business Media Dordrecht. All rights are reserved.
Article
The galaxioid fishes are the dominant, most speciose group of freshwater fishes (with >50 species) in the lands of the cool southern hemisphere, with representatives in western and eastern Australia, Tasmania, New Caledonia, Lord Howe Island, New Zealand, the Chatham, Auckland and Campbell Islands, Patagonian South America (Chile, Argentina), the Falkland Islands and South Africa. The group is most diverse in Australia and New Zealand. Lepidogalaxiidae is found only in Australia, Retropinnidae in Australia and New Zealand, and Galaxiidae across the entire range of the group. Many species are in serious conservation crisis for a diversity of reasons, including habitat deterioration and possibly fisheries exploitation, but there is enduring and pervasive information that shows that the group has been seriously impacted by the acclimatisation of salmonid fishes originating in the cool-temperate northern hemisphere, particularly brown and rainbow trout. With few exceptions, where these trout have been introduced there has been major decline in the galaxioids, especially Galaxiidae, as a result of a complexly interacting series of adverse impacts from these introduced fishes. In some places, centrarchids and cichlids may also have adverse impacts. In addition, there appear to have been adverse impacts from the translocation of galaxioids into communities where they do not naturally occur. In many instances it appears that displacement of the galaxioids has led to a situation where galaxioids and salmonids no longer co-occur, owing either to displacement or predation, leading to fish communities in which there is no explicit evidence for displacement. These effects are resulting in the galaxioid fishes being amongst the most seriously threatened fishes known.
Article
Diets of 18 species of larval Leptoceridae were examined by gut analysis supplemented by observations in the field and laboratory. Food items were leaves of terrestrial origin, aquatic macrophytes, filamentous algae, animal matter, wood and fine detritus. The majority of species were large-particle detritivores (some with a tendency to herbivory), one species was predatory, and one ate fine detritus. Little selectivity was shown; availability of food items was generally more important in influencing the diet. Possible selectivity for freshly fallen green leaves of terrestrial origin was seen in many species and for wood in some species of Triplectides. Larvae were found to be feeding on whatever they were collected from, which had implications for the results of this study because this factor was not taken into consideration during collection. Feeding on the surface of the water was noticed in four species, and two of those may have utilized the surface drift as a food source.
Article
[Une espèce nouvelle d'Allanaspides (Allanaspides hickmani) du sud-ouest de Tasmanie est décrite. Les différences principales entre A. helonomus et A. hickmani sont illustrées et rassemblées dans un tableau., Une espèce nouvelle d'Allanaspides (Allanaspides hickmani) du sud-ouest de Tasmanie est décrite. Les différences principales entre A. helonomus et A. hickmani sont illustrées et rassemblées dans un tableau.]
Article
The larger invertebrates were quantitatively removed from a quadrat of sand 0.5 m² in area on the shore of Lake Pedder (Tasmania) shortly before it was artificially flooded. The numerically dominant animal was Colubotelson (Phreatoicidea). Phreatoicids have not been recorded from freshwater psammon elsewhere. Five species of nematode are recorded from Australia for the first time. Two of these are presently known only from the southern hemisphere.
Article
Surface waters of the Lake Pedder area are characterized by low salinity, low pH, high colour, and a relative major-ion composition near that of seawater. Factors determining this composition are predominance of inert rocks, a covering of sedgeland peat isolating waters from rock contact, and a high rainfall brought by prevailing oceanic winds. Frequency and intensity of rainfall appear to determine the pattern of chemical variation. Salinity, bicarbonate, and pH may change rapidly during periods of high rainfall. Humic acids are important chemical constituents of the waters, and probably determine the type of biotic community which inhabits them.
Article
1. The flooding of a lake basin initiates a series of changes leading eventually to a more stable climax situation after some years. Sequential physical and chemical changes in the mud and water and related changes in the animal and plant populations of three types of tropical African lakes are considered. The giant man-made lakes, Kariba and Volta, both several thousand square kilometres in area, provide the bulk of the material for this review. Two other kinds of tropical lake, the annual storage-reservoirs like Jebel Aulia and Sennar in the Sudan, and natural lakes subject to periodic droughts, like Lake Chilwa in Central Africa, are also considered. Evidence is often patchy but suggests a number of generalizations regarding the course and causes of the developmental changes in these tropical ecosystems.
Article
Examination of the gut contents of mud-dwelling animals in three newly flooded lakes shows terrestrial organic matter to be a major component, particularly during filling of the lake basin. After filling is complete, a fall-off in total biomass of fauna is usually accompanied by significant reduction in the proportion of terrestrial detritus in favour of algal food. It is concluded that newly formed lakes pass through two phases. During flooding they are dependent on the terrestrial ecosystem. This is followed by a switch, immediately after filling, to more self-sustained autochthonous-based food chains.
limnological investigation of Lake Pedder, Tasmania, 1-4 Lake Pedder : its importance to biological science; in: Pedder Papers: Anatomy of a Decision
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BAYLY, I.A.E., PETERSON, J.A., TYLER, P.A., & WILLIAMS, W.D., limnological investigation of Lake Pedder, Tasmania, 1-4 March 1966; Australian Society for Limnology Newsletter, No. 5(2), p. 30 - 41. 1966:Preliminary BAYLY, I.A.E., LAKE, P.S., SWAIN, R., & TYLER, P.A., 1972: Lake Pedder : its importance to biological science; in: Pedder Papers: Anatomy of a Decision, p. 41 - 49, Australian Conservation Foundation, Melbourne
The fate of Lake Pedder and its biota
  • I A E Bayly
BAYLY, I.A.E., 1965: The fate of Lake Pedder and its biota; Australian Society for Limnology Newsletter, No. 4(2), p. 26 -30.