Table Of ContentRecords of the Western Australian Museum 20: 31-37 (2000).
Fish associations within the different inland habitats of
lower south-western Australia
David L. Morgan and Howard S. Gill
Division of Science and Engineering, Murdoch University,
South Street Murdoch, Perth, Western Australia 6150, Australia
email: [email protected]
Abstract - In order to determine whether certain fish species or groups of
species are associated with the different habitat types occurring in the inland
waterbodies of south-western Australia, 239 sites sampled between Margaret
River and Broke Inlet were assigned to appropriate Ramsar wetland
categories and their fish assemblages then subjected to classification. Each of
the sample sites fell into one of the following categories, pools (ephemeral or
permanent), riverine (fresh or salt affected), reservoirs, lacustrine (fresh or
saline) or estuarine. One-way analysis using ANOSIM in the PRIMER
package suggested that the fish communities of the ephemeral pools were
significantly different to those of the rivers and lakes. Thus, the ephemeral
pools were characterised by the presence of the endemic and restricted
species, Lepidogalaxias salamandroides and/or Galaxiella nigrostriata, whereas
the permanent rivers and lakes of the region were characterised by a fauna
dominated by the other small endemic freshwater teleosts, i.e. Galaxias
occidentalis, Galaxiella miinda, Bostockia porosa, Edelia vittala and hlannatherina
balstoni and in many cases the lamprey Geotria australis. ANOSIM also showed
that there were significant differences between the fish faunas in each of the
freshwater habitats in the study region when compared to the estuarine and
salt affected waterbodies of the region. The species most commonly
encountered in the estuarine and salt affected sites included the estuarine
affiliated Leptatherina ivallacei and Pseudogobius olorum, the endemic G.
occidentalis and also the introduced Gambusia holbrooki.
INTRODUCTION Ramsar categories BIO (seasonal/intermittent
freshwater ponds and marshes on inorganic soils)
In 1971, several countries met in Ramsar, Iran to
and B15 (peatlands; forest, shmbs or open bogs),
identify and discuss wetlands of international
while salt affected waterbodies are not included in
importance. Since that time, interest in wetlands has
the classification (Phillips, 1993). The absence of a
been increasing such that there are currently 106
category for saline affected waterbodies is probably
countries which are signatories to w'hat is now
due to their relative paucity in the populated areas
known as the Ramsar Convention (Phillips, 1993;
iucn.org/themes/ramsar/about_infopack_4e.htm of the northern hemisphere (e.g. Europe and North
America) (Williams, 1988; Phillips, 1993). The
4/9/1998). One of the outcomes of this convention
unnatural salinisation of waterbodies, however, is
was the development of numerous wetland habitat
not confined to the south-west of Australia, but is
categories, which, in order to suit Australian
becoming increasingly common in semi-arid regions
conditions, have subsequently been modified by the
of the world such as south-eastern Australia and
Australian Nature Conservation Agency (Phillips,
southern and northern Africa (see for example
1993). These broadscale types of habitat include, to
Williams, 1988; Morelli and Drewien, 1993; Shaw
name a few, freshwater and estuarine reaches of
and Newton, 1993).
rivers, freshwater and saline lakes, permanent and
ephemeral pools and also artificial waterbodies of While it is known that some of the freshwater fish
various kinds. Although many of the waterbodies species found in south-western Australia have very
located in the south-western comer of Australia can restricted distributions and occur in very specific
be easily placed into one of the above modified habitat types, e.g. the salamanderfish Lepidogalaxias
Ramsar categories, others are either combinations salamandroides is essentially restricted to some
of Ramsar's categories or fall outside any of their ephemeral pools of the peat flats (Christensen, 1982;
definitions. For example, the ephemeral pools of the Pusey and Edward, 1990; Morgan et al, 1998), other
peat flat region occur, by definition, on organic/ species, such as the western minnow Galaxias
humic soils and are thus a combination of the occidentalis, nightfish Bostockia porosa and western
32 D.L. Morgan, H.S. Gill
pygmy perch Edelia vittata, are far more widespread i.e. classification dendograms and ordination plots.
and occur in a variety of habitat types (Christensen, These packages can normally only 'handle' a set
1982; Allen, 1989; Pusey and Edward, 1990; Morgan maximum small to moderate number of samples,
et al, 1998). e.g. TAXAN2 - 100 samples, SPSS-X - small to
The first aim of this paper was to define, for lower moderate number of samples (not defined),
soutlvwestem Australia, the main waterbody types PRIMER - 124 samples. As the current study
using Ramsar's definitions, and where necessary sampled more than 400 sites (= 400 samples) (see
provide new/modified habitat definitions. The Table 2 in Morgan et al., 1998), a rationalisation and
second aim, using the data presented in Table 2 of reduction of sites for inclusion in these analyses was
Morgan et al. (1998), was to determine if certain fish necessary. Thus, the 239 sites sampled in the
species or groups of species are associated with waterbodies between Margaret River and Broke
specific habitat types. Inlet (see Table 2 in Morgan et al., 1998) were
selected for this part of the study as this region
contains the majority of fish species that inhabit
MATERIALS AND METHODS inland waters in south-western Australia, and this
region also incorporates all of those different
Selection of data to be included in analyses habitats defined above. Furthermore, this region
This study utilizes data collected in the area also contains the largest river system in south¬
between Margaret River and Broke Inlet (see western Australia, as well as both cleared areas and
Table 2 in Morgan et al., 1998). The association some of the least disturbed areas of south-western
of species and/or suites of species within Australia. Of the 239 different sites sampled during
particular habitats was determined by this study in the above watersheds, fish were not
estimating the similarity of the fish faunas based captured in 55 and these sites were thus omitted
on the presence or absence of each species in from further analyses. Furthermore, adjacent and
each site. It should be noted that presence/ seasonally connected sites were amalgamated if
absence data were preferred over abundance they were of the same habitat type and contained a
data for this study as all sites were not sampled similar suite of species. This reduced the total
in the same season and that the relative number of sites for analysis to 123, which is a
abundances change markedly between seasons suitable number for analyses to be performed using
in the south-west of Australia. For example, PRIMER.
during winter, when the region receives the
majority of its rainfall, water levels are Classification of sample sites, ANOSIM and
extremely high and fish densities are SIMPER
consequently greatly reduced. In contrast, On the basis of a species presence or absence, the
during summer, when there is little or no rain distribution of the different fish species amongst the
and evaporation is high, water levels fall 123 sites was used to construct a similarity matrix
dramatically and fish densities increase employing the Bray-Curtis similarity coefficient in
substantially. Thus, while the relative abundance PRIMER (Clarke and Warwick, 1994). To illustrate
of species at each site could not be confidently the extent of similarity in the faunal composition of
estimated, intense sampling at each site using these sites, the matrix was then subjected to
several techniques (e.g. gill, seine, larval and classification using PRIMER (Clarke and Warwick,
scoop nets, electrofishing etc, see Morgan et al., 1994). In order to test the proposition that the
1998 for precise details) provided a high degree different broad habitat types outlined above will
of conviction that all of the species of fish contain different fish faunas, the 123 sites sampled
present at each site were likely to have been were a priori allocated to one of these habitats and
captured. the significance of any faunal differences between
Sites representing each of the following habitat these broad groups was tested by one-way analysis
types in lower south-western Australia as defined using ANOSIM in the PRIMER package (Clarke and
by Ramsar, i.e. permanent rivers and streams, Warwick, 1994).
permanent lakes, permanent freshwater pools, Since more than half, i.e. 63, of the sample sites
estuarine or intertidal waters and water storage were within group V in tire initial classification (see
areas, e.g. dams, and those habitats not defined by Figure 1), and as the other groups were likely to have
Ramsar, i.e. ephemeral pools and salt affected strongly influenced the expression of variation
waterbodies, were included in the analyses. within this group of the classification, the sites in
It should be noted that those statistical packages group V were separately subjected to classification.
which are currently available for generating The species that distinguish the two large resultant
similarity matrices and for the subsequent testing of groupings from each other within this classification
these matrices, utilise agglomerative techniques to (see Figure 2), were then determined using SIMPER
provide visual representations of any associations. (similarity percentages) (Clarke and Warwick, 1994).
Freshwater fish assemblages of south-western Australia 33
Q BRAY-CURTIS SIMILARITY
100
V-1-1-1-1-1-1- —I
m Headwater
streams and
seasonal
pools
IV
Saline
rivers
Predominantly
fresh pools,
streams and
lakes
Ephemeral
pools
Estuarine
and saline
rivers and
lakes
Figure 1 Classification of the sites sampled for fish in the water catchments between Margaret River and Broke Inlet,
inclusive, in lower south-western Australia. N.B. The site numbers are given. For the locality of each site and
its associated fish fauna see Table 2 in Morgan et al. (1998).
RESULTS Afttrcagobius suppositus. All of these sites were either
Classification of the different fish faunas at the estuarine or salt affected waterbodies. Group II
different sampling sites produced five major groups comprised those sites that were of an ephemeral
(Figure 1). The first group of sites (I) was dominated nature and contained predominantly L.
by species with marine affinities, i.e. the western salamandroides and/or the black-stripe minnow
hardyhead Leptatherim zoallacei, Swan River goby Galaxiella nigrostriata. However, other endemic
Pseudogobius olorum and big headed goby freshwater teleosts, such as G. occidentalis, B. porosa
34 D.L. Morgan, H.S. Gill
30 BRAY-CURTIS SIMILARITY 100
Site Habitat Species
(1) 7. II
(3) 7
1
3. 6.7. 9, 13. 15
3. 1^, i3-15
Bi 3, 6-9, 13. 14
6. 7. 9. 14. 15
(7) 6. 7. 9. 13-15
33)) 63.. 67.. 79. 9
3) 3. 6-9
3) 3. 5-9
3) 3. 6. 7. 9. 13
3) 3. 6-9, ll 14
3) 3. 6. 7. 9. 13-15
7) 3. 6. 7. 9. 15
(3) 3. 6. 7. 9. 14
i 3. 6. 7. 9. 14
3. 6. 7. 9. 14
3. 6. 7. 9
3. 7. 14
3. 7. 14
3. 7. 14
3. 5.7
3. 7
3. 7
3, 7
3. 7
3. 4, 7. 8
2-4. 7. 8
2-4, 6-8. 10. 11
2. 3. 6-1 11
2. 3. 6-8
2-4. 6-8
2-8
2-8
6-8
6. 7
3. 6. 7. 9. 11. 12. 14
3. 6. 7. II
3. 6-8, 11
3. 6. 1 10-12
3. 6. 7. 11-12
3. 6. 7. 10. 11
3. 6
3. 6. 14
3. 6. 7. 14
3. 4. 6. 7. 14
1. 3. 6-8
5-7
3, 5-8
3. 5-8
3. 5-7
3. 5-7
3. 5-7
3. 6. 7. 13
3. 6. 7. 13
2. 3. 6. 7
3. 4. 6. 7
3. 4. 6. 7
3. 6. 7
3. 6. 7
3. 6. 7
3. 6. 7
Habitat typg Species
(1) Ephemeral pools 1. Tandanus bostocki
(2) Permanent pools 2. Lepidogedaxias salamandroides
(3) Freshwater rivers and streams
(4) Freshwater lakes 3. Galaxias occidentalis
(5) Estuarine 4. Galaxiella nigrostriata
(6) Saline rivers 5. Galaxiella munda
(7) Dams
6. Bostockia porosa
I. Edelia viltata
8. Nannalherina balstoni
Figure 2 Further classification of the sites in Group V
of Figure 1. The site number (see Table 2 in 9. Geotria australis
Morgan ct a\. (1998)) and the prevailing 10. Leptatherina wallacei
habitat type, as well as those species present
II. Pseudogobius olorum
at each site, are given. N.B. For Geolria
australis - ammocoetes (larval) are 12. Afurcagobius supposilus
represented by an italicised 9, adults by a 13. Oncorhynchus mykiss or Salmo trulla
bolded 9 and when both are present a
standard (i.e. not bolded or italicised) 9 is 14. Gambusia holbrooki
given. 15. Perea/luviatilis
Freshwater fish assemblages of south-western Australia 35
and E. viltata, were also commonly found in these species that were found in most sites included £,
environments, which they utilise as both spawning vittata, B. porosa and G. occideutalis. The larger group
and nursery grounds. The small number of sites (III) contained these three latter species at most
that comprised group III were either headwater sites, and were of a wide range of habitat types, e.g.
streams or seasonal water bodies and were ephemeral and permanent pools, freshwater rivers
characterised by the presence of the mud minnow and streams, freshwater lakes, saline rivers and
Galaxiella munda and either one or two other dams.
endemic species (Figure 1). The sites in group (IV) The distinct differences between the species
in Figure 1 were from saline rivers, and were composition in the saline waters (e.g. estuarine and
characterised by the presence of the introduced Blackwood River) and the fresh waters in south¬
Gambusia holbrooki, but also included G. occidentalis, western Australia are further highlighted when the
L wallacei, P. oloriim and to a lesser extent B. porosa fish faunas of the different habitat types (i.e.
and Oncorhynchus mykiss/Salmo trutta. Group V, ephemeral pools, permanent pools, fresh rivers,
which contained the majority of sites sampled, i.e. lakes, estuarine, salt affected rivers and dams) are
63, comprised those sites with a relatively 'natural' subjected to one-way analysis using ANOSIM.
assemblage of fishes, with the dominant species Thus, ANOSIM showed that there were indeed
being those that are endemic to the south-west of significant faunal differences (p<0.05) between each
Australia and also the lamprey Geotria australis. of the freshwater habitats in the study region when
Furthermore, those species which have been compared to each of the saline habitat types.
introduced into the region, such as the mosquitofish ANOSIM also showed that there were significant
G. holbrooki, redfin or Eurasian perch Perea fluviatilis differences (p<0.05) between the fish fauna of
and the trout species O. niykiss/S. trutta were also ephemeral pools of the region and those of the
recorded in some of these sites. The habitats within rivers and lakes, this being a reflection of the
this group included both ephemeral and permanent absence of L. salamandroides and G. nigrostriata from
pools, streams, lakes and dams (Figure 1). the vast majority of the latter habitats (Table 1).
When the samples for Group V were classified The tabulation of the number of sites at which
separately, three distinct groups were apparent each species occurred for each of the habitat types
(Figure 2). The first group (I) in this dendogram further illustrates the associations described above
contained two outliers, with the first site containing (Table 1). Thus, £. salamandroides and G. nigrostriata
only £. vittata, while the other contained £. vittata were essentially restricted to the pools of the region,
and P. olorum. The classification then, with respect being found in 25 and 24 of the 32 ephemeral pools
to the remaining sites, produced two main groups .sampled, and in two and five of the 10 permanent
(Figure 2). The smaller group (II), which contained pools sampled, respectively. In contrast, G.
exclusively freshwater riverine or dammed sites, occidentalis, B. porosa and £. vittata were most
was shown by SIMPER to be characterised by the frequently found in permanent freshwater habitats,
presence of G. australis. Within this group, the other i.e. lakes, rivers and pools. Thus, these three species
Table 1 The number of sites within each broad habitat type, between Margaret River and Broke Inlet, that each of the
inland fish species of south-western Australia were captured. The total number of sites sampled in each
habitat type is also given.
Habitat type
Species Ephemeral Permanent Riverine Lakes iE stuarine Salt affected Dams Salt lakes TOTAL
pools (32) pools (10) (32) (16) (7) (17) (8) (1) (123)
Tandamts bostocki 1 1 2
Lepidogalaxias salamandroides 25 2 27
Calaxias occidentalis 8 8 24 15 1 8 2 66
Galaxiella nigrostriata 24 5 2 31
Galaxiella munda 3 4 5 1 13
Bostockia porosa 6 7 26 10 3 2 59
Edelia vittata 9 7 29 15 3 5 68
Nannatherina balstoni 3 5 4 4 16
Geotria australis 15 4 17
Leptalherina wallacei 1 1 4 9 1 16
Pseudogobius olorum 2 1 2 2 7 6 1 20
Afurcagobius suppositus 2 1 2 1 6
Oncorhynchus mykiss/Salmo trutta 7 5 12
Gambusia holbrooki 10 5 12 5 32
Perea fluviatilis 5 3 8
36 D.L. Morgan, H.S. Gill
were captured in 49, 45 and 56 of the 66 permanent such systems. In contrast, the introduced G.
freshwater habitats sampled, respectively (Table 1). holbrooki and also those species commonly
The remaining two small endemic species, G. nnmda associated with estuaries, i.e. L. wallacei and P.
£md N. balst07ti, were much rarer, being found only olorum, are likely to either become more prevalent
in ephemeral pools (three each), permanent pools in waters which have higher than 'normal' salinities
(four and five, respectively) and in riverine sites or are not going to be affected by such conditions.
(five and four, respectively). Nannatherina balstoni The salinisation of many freshwater habitats,
was also captured in four lakes. The freshwater through land clearing within the immediate
catfi.sh or cobbler Tandanus bostocki was very rarely catchment, is increasing in south-western Australia
captured during this study. and is causing the extinction or decline in
Leptatherina wallacei was not captured in the populations of other aquatic fauna and also flora,
freshwater rivers of the region. It was, however, and consequently, is having major effects on stream
found in one fresh and one salt lake, four estuarine ecology (Hart et ai, 1991; Pen, 1997). Thus, while
sites and nine salt affected river sites. Similarly, P. certain macrophytes, microalgae, fringing
oloriim was most often found in estuarine (seven) vegetation, invertebrate species and waterbirds may
and salt affected sites (six), but also in freshwater increase in abundance in such saline systems, others
rivers (two) and lakes (two) and in one salt lake. may decline (Hart et ai, 1991; Williams, 1995).
Both of the latter species were very occasionally Within the Blackwood River (the largest salt
captured in ephemeral pools (Table 1). The other affected river in Western Australia with an average
species that is commonly associated with estuaries, annual increase in dissolved salts of ca 15 mg/L
i.e. A. suppositus (see Morgan et ai, 1998), was found (Schofield and Ruprecht, 1989; Pen, 1997)), for
in two estuarine sites, one freshwater lake, one salt example, Williams et al., (1991) found little or no
affected river and two freshwater riverine sites. The longitudinality with regard to faunal composition
lamprey G. australis was only captured in riverine of this system, despite the salinity gradient along its
sites (15) and in dams (two), as were the introduced length. Although this is likely to be a consequence
trout (seven and five sites, respectively) and P. of an increase in halotolerant species, it presumably
fluviatilis (five and three sites, respectively). The also indicates that there has been an elimination of
remaining introduced species, G. holbrooki, was less tolerant species that once characterised a more
captured on more occasions, being found in 32 sites diverse system (Trayler et al., 1996). It could
in both fresh (10) and salt affected (12) rivers, lakes therefore be argued that the increasing salinity in
(five) and dams (five) (Table 1). the Blackwood River is resulting in a loss of
populations of endemic freshwater teleosts and a
concomitant increase in halotolerant species such as
DISCUSSION L. wallacei, P. olorum and G. holbrooki.
While two of the endemic freshwater species of It is worth noting that when the introduced
south-western Australia, i.e. L. salamandroides and species G. holbrooki and P. fluviatilis were present in
G. nigrostriata, are essentially restricted to artificial environments, e.g. dams, the native species
ephemeral pools, the five remaining small endemic were rarely captured. In contrast, in riverine sites,
freshwater teleosts are found in a wider variety of native and introduced fish species were often found
habitat types such as streams, lakes and ephemeral together, however, during the periods when water
and permanent pools. Of these latter species, N. levels were greatly reduced and sections of rivers
balstoni and G. mtinda were found in fewer sites than became a series of small pools, native fish were
the other small endemics, namely G. occidentalis, B. usually absent in those pools that harboured P.
porosa and £. vittata (see Table 1; Morgan et al., fluviatilis and/or the tw'O trout species. When the
1998). It should be noted that, like L. salamandroides results of this study are considered in conjunction
and G. nigrostriata, N. balstoni and G. munda are with the studies of Hambleton et al. (1996), Morgan
restricted in their distribution and are most and Gill (1996) and Gill et al. (1998), it becomes
common in the waterbodies of the peat flats. evident that the small endemic freshwater teleosts
Since G. occidentalis, G. holbrooki, L. wallacei, P. of south-western Australia are vulnerable to the
olorum and A. suppositus were all found in a wide continuing loss or alteration of habitat and to the
range of salinities, they must be at least moderately introduction of agonistic or piscivorous species such
euryhaline. The other teleosts caught during this as G. holbrooki and P. fluviatilis.
study were almost always captured in fresh waters The fact that adult and larval (ammocoetes) ;
and it can therefore be assumed that these species lampreys were only captured abo\ e four of tlie eight
are either stenohaline or show strong preferences dams sampled may reflect the fact that large dam
for fresh water. The results presented in this paper walls can act as a major barrier to the upstream
demonstrate that the salinisation of water bodies in migration of lampreys and tliat dams may also modify
south-western Australia is likely to cause a decline flow regimes and thereby cause adverse changes to )
in the number of endemic freshwater species in the .sediment composition of ammococte beds. j
Freshwater fish assemblages of south-western Australia 37
While this paper has provided data on the broad A review of the salt sensitivity of the Australian
scale habitat associations of the fishes of lower freshwater biota. Hydrobiologia 210: 105-144.
south-western Australia, it does not provide Morelli, ]. and Drewien, G. (1993). S<iuth Australia. In
information on their specific habitat requirements, Usback, S. and James, R., (eds), A Directory of
preferences and tolerances, e.g. suitable spawning Important Wetlands in Australia. Canberra: Australian
substrate, flow regimes, preference for complex Nature Conservation Agency.
habitats, and pH and salinity tolerances. Future Morgan, D.L. and Gill, H.S. (1996). The effect of Big Brook
dam during drought on the fish communities of the Lefroy
studies should therefore be aimed at the provision
and Big Brooks. Unpublished Report to the Water and
of such information, which will aid in both the
Rivers Commission of Western Australia.
formulation of management plans for the
Morgan, D.L., Gill, H.S. and Potter, I.C. (1998).
conservation of this unique fauna and also the
Distribution, identification and biology of freshwater
identification of prospective habitats for their re-
fishes in south-western Australia. Records of the
introduction. Western Australian Museum Supplement No. 56, 97 pp.
Pen, L. (1997). A Systematic Overview of Environmental
Values of the Wetlands, Rivers and Estuaries of the
ACKNOWLEDGEMENTS Busselton-Walpole Region Water and Rivers
Financial support for this project was provided by Commission, Water Resource Allocation and
the Natural Heritage Trust, Water and Rivers Planning Report Series No. WRAP 7.
Commission of Western Australia, Fisheries WA, Phillips, B. (1993). Introduction. In Usback, S. and James,
National Fishcare and Murdoch University. R. (eds), A Directory of Important Wetlands in Australia.
Thankyou to Steven Head, Murray Stevenson, Canberra: Australian Nature Conservation Agency.
Simon Visser, Dean Campbell-Smith, Paul Wright Pusey, B.J. and Edward, D.H. (1990). Structure of fish
and Simon Hambleton for their invaluable help assemblages in waters of the southern acid peat flats,
south-western Australia. Australian Journal of Marine
with the extensive sampling and to Margaret Platell
and Freshwater Research 41: 721-734.
for her comments on the manuscript.
Schofield, N.J. and Ruprecht, J.K. (1989). Regional
analysis of stream salinisation in south-west Western
Australia. Journal of Hydrology 112:19-39.
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