baseline assessment of freshwater mussel populations ... · baseline survey of freshwater mussel...
Post on 23-May-2020
3 Views
Preview:
TRANSCRIPT
Report to:
MW Klunzinger, D Strebel, SJ Beatty, DL Morgan & AJ Lymbery
Centre for Fish & Fisheries Research Murdoch University
December 2011
BASELINE ASSESSMENT OF FRESHWATER
MUSSEL POPULATIONS WITHIN THE URBAN
WATERWAYS RENEWAL PROJECT
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
2
Authors: MW Klunzinger, D Strebel, SJ Beatty,
DL Morgan & AJ Lymbery
Centre for Fish & Fisheries Research,
Murdoch University
December 2011
BASELINE ASSESSMENT OF FRESHWATER
MUSSEL POPULATIONS WITHIN THE URBAN
WATERWAYS RENEWAL PROJECT
Report to:
Frontispiece: from top to bottom – Bickley Brook facing downstream towards the confluence with Canning River, near Royal
Street bridge, Gosnells, WA. Carter’s freshwater mussel (Westralunio carteri) photos: Michael Klunzinger.
Acknowledgements: This survey was funded by SERCUL for the
Urban Waterways Renewal Project. We would
like to thank Julie Robert, Dr Judith Fisher, and
Brett Kuhlman for project coordination. We
especially thank Alice Atkinson, Matt Grimbly,
volunteers Sara and Nick for field assistance
and Monica Estrada and Shaun Meredith for
organising water quality data acquisition.
Thanks also to Tim Storer for providing
information on salt-affected marron.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
3
Summary & Recommendations
No live freshwater mussels (Westralunio carteri) were found in Sites 1BC (Bannister
Creek), 2BBC (Bickley Brook – Canning River Confluence), 8WR (Wungong River) or 9RL
(Wungong River - Riverside Lane) of the Urban Waterways Renewal Project.
Only empty shells of W. carteri were found within the Canning River between Royal
Street Bridge and ~50 m downstream from the Bickley Brook Confluence, which was
probably the result of mass mortality from a salt wedge that moved upstream above the
Kent Street Weir in February 2011.
Salinisation of this normally freshwater section of the Canning River was further
evidenced by the colonization of Fluviolanatus subtorta, a normally estuarine species of
mussel which is usually not found in freshwater habitats. Numerous F. subtorta had
attached to the empty shells of W. carteri, carapaces of Smooth Marron (Cherax cainii)
as well as woody structures within the river.
No W. carteri shells were found within Bannister Creek, Bickley Brook or the Wungong
River sites.
The salt wedge was also probably responsible for 100% mortality of W. carteri within
Yule Brook, near SERCUL.
Live W. carteri within the Canning River were found near Homestead Park, extending
downstream to 300 m above the Royal Street Bridge.
Although live freshwater mussels were found within Yule Brook in October 2009, and
above Nicholson Rd Bridge within the Canning River, this survey indicates that W. carteri
is now likely to have become locally extinct within a ~8.5 km stretch of the Canning.
Shell measurements indicate that most W. carteri within these extinct populations were
aging and lacked new recruits and even where live W. carteri were surveyed, very few
young mussels (<40mm long) were located and a majority were >60mm in length.
Dense root mats of Swamp Paperbark (Melaleuca rhaphiophylla) and Flooded Gum
(Eucalyptus rudis) within the river harbored the largest densities of W. carteri (up to 65
mussels/m2) and appeared to be important habitats for recruitment because these were
the only areas within our surveys that had younger mussels (<40 mm). Furthermore,
mussel densities and abundance decreased as we moved further away from the river
banks and become virtually non-existent within the middle of the river channel.
Westralunio carteri is becoming increasingly rare in the Swan-Canning catchments,
having once extended from the Avon River into the Swan and Canning Rivers and their
major tributaries from the drinking water catchments to within the areas which are now
largely estuarine. A comprehensive assessment of the species within the remaining
populations in the tributaries of the Swan-Canning catchments and the Canning River is
necessary to determine the viability of the species in the near future.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
4
The loss of this species may have unknown consequences for water quality within these
catchments. Freshwater mussels are generally known to filter large volumes of water
and have been shown to improve eutrophic catchments in Europe, USA and New
Zealand. Thus, a quantified study of filtration rates and algae removal capacity of W.
carteri is necessary to determine their importance, to estimate their potential as a
bioremediator of nutrients and predict how their loss will impact the rivers.
Recolonisation of W. carteri within UWR sites will largely depend on the availability of
freshwater (i.e. <2.0 ppt salinity), suitable habitats for adult and juvenile mussels as well
as the necessary host fishes upon which the parasitic larvae (‘glochidia’) of W. carteri
depend for development, survival and dispersal. Provision of adequate supplies of
freshwater and mitigation of pollutants such as saltwater, industrial/agricultural and
household chemicals, chlorine and fine sediments is necessary to ensure freshwater
ecosystem function and integrity. Stability of freshwater mussel (W. carteri)
populations should be used as appropriate bioindicators of freshwater ecosystem
function throughout the Swan-Canning catchments and in other regions of the south-
west where the species is found.
The Canning River, Perth, WA
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
5
Contents
Summary & Recommendations ............................................................................................. 3
Introduction .......................................................................................................................... 6
Urban Waterways Renewal Project ......................................................................................... 6
Aquatic freshwater biodiversity of south-western Australia ................................................... 6
Aims of the study ..................................................................................................................... 9
Methodology ....................................................................................................................... 10
Sampling sites ........................................................................................................................ 10
Freshwater mussel sampling ................................................................................................. 20
Water quality data ................................................................................................................ 22
Statistical analysis ................................................................................................................. 22
Results and discussion ......................................................................................................... 22
Freshwater mussel distribution and abundance ................................................................... 22
Freshwater mussel population structure ............................................................................... 26
Water quality ......................................................................................................................... 28
Conservation implications and recommendations ................................................................ 30
References .......................................................................................................................... 32
Appendix ............................................................................................................................. 35
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
6
Introduction
Urban Waterways Renewal Project
The Swan and Canning River catchments were identified as a coastal ‘hot spots’ owing to high
nutrient loads in 2006. The Australian Government subsequently funded the Swan River Trust
to develop the Swan-Canning Water Quality Improvement Plan (WQIP) with an aim to reduce
nitrogen and phosphorus inputs within the catchments (SRT 2009). Of the 30 sub-catchments
assessed in the Swan-Canning Catchment, priority areas with high nutrient concentrations were
identified and targeted for local WQIPs. Water Quality Improvement Plans have been
developed for Bickley Brook, Southern River and Bannister Creek to assist State and Local
Governments and communities to prioritise management areas for improvement in water
quality.
Within Metropolitan Perth, the ‘Urban Waterways Renewal’ project (UWR), funded by
the Australian Government through Water for the Future – National Water Security Plan for
Cities and Towns program, the South East Regional Centre for Urban Landcare (SERCUL) has
partnered with the Department of Water, Water Corporation, Swan River Trust as well as local
governments within the cities of Canning, Gosnells and Armadale to implement the WQIPs. The
Australian Government is providing $4 million for implementing actions identified in the Swan-
Canning WQIP.
Aquatic freshwater biodiversity of south-western Australia
South-western Australia is home to a unique array of plants and animals, a large proportion of
which are found nowhere else. The freshwater ecosystems of the south-west harbor a highly
endemic assortment of macrofauna which includes 11 species of freshwater fishes (82%
endemic), 11 species of freshwater crayfishes (100% endemic), 2 species of turtle (100%
endemic), 30 species of frogs (93% endemic; 15 species breed in freshwater), many waterbird
species, snakes, water rats and only one species of freshwater mussel (Morgan et al. 1998,
2011; Davis & Christidis 1999; Allen et al. 2002; Nevill 2005; Tyler & Doughty 2009; Wilson &
Swan 2010). Together with other fauna including aquatic and terrestrial macro- and micro-
invertebrates, macrophytes, riparian and terrestrial vegetation, these fauna interact to form a
complex food web with various trophic levels which are strongly influenced by nutrient
concentrations (nitrogen, potassium and phosphorus are particularly important). This survey is
focused on Carter’s Freshwater Mussel (Westralunio carteri), which is one of several indicator
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
7
organisms which will be used as bioindicators of freshwater biodiversity in the UWR project
areas.
Freshwater mussels
Freshwater mussels filter particulates and plankton from the water column, contributing to
water clarity and quality. As they burrow and move through the sediments, they are thought to
enhance benthic oxygenation. Their shells are home to a multitude of other fauna including
hydra, algae, other molluscs, freshwater shrimp, and empty shells can provide shelter for
juvenile freshwater crayfishes and small benthic fishes such as gobies. They are a favoured
food item by water rats and, historically, were important to indigenous peoples for food, tool
use and trade (e.g. Vaughn and Hakenkamp 2001; Walker et al. 2001; Strayer 2008; Klunzinger
2011). Freshwater mussels are sensitive to environmental changes (Ponder & Walker 2003)
and, like freshwater fish fauna, can be considered important bioindicators of aquatic ecosystem
condition (Lymbery et al. 2008; Beatty & Morgan 2010).
Carter’s Freshwater Mussel is endemic to the south-west and found nowhere else
(McMichael & Hiscock 1958; Walker 2004). This bivalve has a unique life cycle in which its
larvae, known as ‘glochidia’ must attach to a host, which is generally a fish to complete its
development to the juvenile mussel stage. This interaction is thought to serve as a dispersal
mechanism (Bauer & Wächtler 2001; Strayer 2008). Until recently, little was known of the
species biology, reproductive development, ecology and its host fishes (Klunzinger et al. 2011a,
unpublished data). Kendrick (1976) documented the disappearance of W. carteri from the
River Avon, presumably as a result of secondary salinisation. In recent years, the species has
undergone population contractions in parts of its range, also presumed to be linked with
salinisation of waterways within the south-west agricultural zones (Keighery et al. 2004) and
was listed as ‘Vulnerable’ under international conservation criteria in 1994 (IUCN 2011). The
species is categorized as ‘Priority 4’ fauna under an interdepartmental listing by the Western
Australian Department of Environment and Conservation (DEC 2011), meaning that the species
is in need of monitoring. Recent work by Klunzinger et al. (2010) has shown that the species is
intolerant of salinities above 3.0 ppt, dehydration can cause localized population reductions
(Klunzinger et al. 2011b) and field reports have shown that low dissolved oxygen (<20%) also
may cause mortality (Klunzinger et al., unpublished data). Despite localized extinctions in
systems such as the Avon River, Moore River, Blackwood River, Kalgan River and others, the
species remains legislatively unprotected (Klunzinger et al., unpublished data).
Freshwater Mussel declines
Freshwater mussels have undergone major declines in population range due to a combination
of habitat change, such as riparian vegetation degradation and secondary salinisation of inland
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
8
reaches of the major rivers (Kendrick 1976; Beatty et al. 2010a; Klunzinger et al. 2010,
unpublished data); impacts from sedimentation, loss of host fishes, barriers to host fish
migrations, inability of glochidia to successfully transform on feral fishes, predation by feral
animals, contaminants such as heavy metals and chemicals, eutrophication leading to anoxia,
exotic macrophyte blooms (e.g. Salvinia molesta), drought, lack of environmental flows,
destruction from construction projects and livestock trampling (e.g. Walker et al. 2001; Beatty
et al. 2010b; Jones & Byrne 2010; Klunzinger et al. 2011b). Salinisation of inland areas has
resulted in only ~44% of flow in the largest 30 rivers in the south-west of WA remaining fresh
(Mayer et al. 2005).
Examples of threats to freshwater mussels: (A) Drying; (B) Barriers to host fish migrations;
(C) Salinity/drought; (D) Erosion/sedimentation; (E) Livestock trampling; (F) Salvinia
molesta. Photos: A - E - Michael Klunzinger; F – WRC 2002.
(A) (B)
(D) (C)
(E) (F)
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
9
Aims of the study
The aims of this study were to:
Determine whether freshwater mussel populations are present within the study area.
Determine the distribution and population structure of freshwater mussels in Urban
Waterways Renewal sites.
Interpret results of surveys and identify priorities for management.
Carter’s freshwater mussel, an important bioindicator of freshwater ecosystem health in south-western Australia. (photo: M. Klunzinger)
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
10
Methodology
Sampling sites
A total of 4 pre-defined UWR sites (Figure 1) were assessed using qualitative
(presence/absence) and quantitative (abundance and density) methods to provide details of
the freshwater mussels within Bannister Creek (site 1BC; Figure 2), Bickley Brook – Canning
River Confluence (site 2BBC; Figure 3). Additional sites within the Canning River near the Royal
Street Bridge included an area between (32°02.046'S, 115°57.160'E) and (32°02.605'S,
115°57.956'E) (see Figure 4). Other UWR sites were surveyed within the Wungong River (sites
8WR and 9RL; Figures 5 and 6) in the cities of Canning, Gosnells and Armadale, respectively.
The Canning River near Homestead Park between (32°03.138'S, 115°58.262'E) and (32°02.825'S,
115°58.079'E) (see Figure 7) and Yule Brook near SERCUL between (32°02.024'S, 115°57.058'E)
and (32°02.046'S, 115°57.160'E) (see Figure 8) were also surveyed.
In order to provide an overall summary of the previously known distribution of
freshwater mussels in the Canning River catchment, the MusselWatchWA distributional
database was accessed and the distribution of freshwater mussels in this catchment was then
mapped and included for comparison (Figure 9).
UWR sites sampled for freshwater mussels. (A-B) Bannister Creek; (C-D) Bickley Brook –
Canning River Confluence; (E-F) Wungong River.
(A)
(C)
(E) (F)
(B)
(D)
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
11
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
15
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
16
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
17
Quadrats 1-5
Quadrats 6-10
Quadrats 26-30
Quadrats 16-25
Figure 9 Distribution of Westralunio carteri in the Swan-Canning catchment (excluding this study). Data
maintained by the authors in the MusselWatchWA database.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
20
Freshwater mussel sampling
At each site, a 50 m stretch of stream was visually examined for freshwater mussels from the
water surface using a bathyscope or feeling for mussels by hand when water clarity was poor.
Where mussels were found, relative abundance and density was determined by counting the
number of mussels in 1 m2 quadrats which were randomly placed on the stream bed at each
site as per Strayer & Smith (2003). Quadrats were constructed of 15 mm diameter round PVC
tubing and open elbows. At each site, we recorded substrate type on the river bottom (rock,
gravel, sand, mud, silt and/or detritus, woody debris, etc.). For each mussel collected from the
quadrats, the maximum length (ML), maximum height (MH) and width (W) of the shell was
measured with mechanical callipers to the nearest 0.01 mm (Figure 10). Mussels were
identified to species level as per McMichael & Hiscock (1958) and Walker (2004). All mussels
were released after being measured, but empty shells were retained for future study.
Maximum Height Index (MHI) and Shell Obesity Index (WLI) according to McMichael & Hiscock
(1958) was derived from the following formulas:
and
.
A bathyscope was used to search for freshwater mussels (right) and when found, density was
determined by counting the number of mussels in 1 m2 PVC quadrats (left).
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
21
Figure 10 Morphological measurements of freshwater mussels using mechanical callipers (methods as
per McMichael & Hiscock 1958 and Walker 2004).
Maximum Height
Maximum Length
Width
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
22
Water quality data
Physico-chemical parameters of water quality (temperature (°C), pH, dissolved oxygen (DO as
%), salinity (ppt) and conductivity (µS/cm)) were measured using an Oakton® PCD650
waterproof portable multimeter and data was obtained from the Department of Water (WA),
SERCUL and the Swan River Trust.
Statistical Analysis
Mapping of faunal distributions was undertaken using ArcGIS® and NearMap® software.
Graphical and statistical analysis of mussel densities, and length-frequencies were undertaken
using SigmaPlot®11.0. Statistically significant differences (P < 0.05) in mussel shell
measurements were determined using Analysis of Variance (ANOVA) in Sigma Plot® 11.0.
Results and discussion Freshwater mussel distribution and abundance
Only empty (dead) freshwater mussel shells were found at Yule Brook and the Bickley
Brook Confluence and within a ~160 m2 area of Canning River associated with Bickley Brook; no
freshwater mussels were found at the Wungong or Bannister Creek sites. A freshwater mussel
kill incident had previously been reported in February 2011, 150 m upstream from the Royal St
Bridge. Although no official report was released, the information was documented (Meredith,
pers. comm.). These mussels probably died from an influx of saline water that breached the
Kent St Weir.
During this study, an additional survey ~2.2 km upstream from Royal Street Bridge, near
Homestead Park, revealed the presence of many live W. carteri. The river was then surveyed
downstream from this point to determine the extent of the remaining populations within the
river reach. The extent of live W. carteri extends to ~450 m upstream of Royal Street bridge.
Since 2009, mass extinctions of the species have occurred along a 8.5 km section of the Canning
River above Kent Street Weir, which probably resulted from dehydration in Yule Brook and
possibly other tributaries in October 2009 and the movement of a salt wedge upstream above
the Kent St Weir from 2010 to 2011 (Klunzinger et al., unpublished data; Meredith, pers.
comm.). The distribution of W. carteri within the Upper Canning River and downstream,
including Canning Dam and associated tributaries, to Roley Pool is largely unknown due to the
inaccessibility of areas associated with drinking water supplies and residential properties.
During this study, Fluviolanatus subtorta, an estuarine species of mussel was found
attached to empty shells of W. carteri (Figure 11) in Yule Brook and Canning River below Royal
St Bridge near UWR Site 2BBC, demonstrating observable salinisation in this area of the river.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
23
Further downstream in the Canning River, near the Kent Street Weir, live Smooth Marron
(Cherax cainii) were also found with many, what appear to be F. subtorta, attached to their
carapace and may even have resulted in the loss of an eye (Figure 11 – Storer, pers. comm.).
Marron are acutely intolerant of salinities above 17 ppt and adults can withstand prolonged
periods of up to 8 ppt, however salinities of <5 ppt are probably required to complete the life
cycle of the species (de Graaf et al. 2010). Elsewhere in the south-west, this estuarine mussel
has been found where habitats have become too salty for the survival of W. carteri (Kendrick
1976; Pen 1999; Klunzinger et al., unpublished data). Several experiments conducted at the
Murdoch University Fish Health Unit revealed that W. carteri is acutely intolerant of salinities
above 3.0 ppt (Klunzinger et al. 2010), which is in agreement with studies of other temperate
Australian freshwater mussels within the same family (Walker 1981; Widarto 1996).
The densities of freshwater mussels surveyed during this study ranged from one to as
many as 65 mussels/m2 within the survey sites (Table 1). Densities were greatest near the river
banks amongst tree roots and woody debris with muddy sand substrates and few, if any
mussels were found in mid-channel runs or in areas that were dominated by extremely soft
organic sludge. A breakdown of the localised distributions of W. carteri within each site are
presented in Figures 6-8. Densities observed within each quadrat are presented in the
Appendix.
Table 1 Density of freshwater mussels (Westralunio carteri) within the study area. Site River Name Density Range
(number of mussels/m2)
Avg. Density (number of mussels/m2)
1BC Bannister Creek Bannister Creek --- 0.0
2BBC Bickley Brook – Confluence Canning River 1-65 8.1 (±1.1) ☠
2BBC Bickley Brook Bickley Brook --- 0.0
8WR Wungong Wungong River --- 0.0
9RL Riverside Lane Wungong River --- 0.0
SERCUL Yule Brook 1-15 2.4 (±0.8) ☠
Homestead Park Canning River 3-48 12.9 (±5.8)
☠Only dead mussels with empty shells were found
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
24
Figure 9 Examples of the estuarine mussel Fluviolanatus subtorta (arrows) attached to the empty shells of
the freshwater mussel Westralunio carteri within the Canning River, near Royal St Bridge
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
25
Figure 11 Examples of clusters of the estuarine mussel Fluviolanatus subtorta (arrows) attached to the
orbital carapace (top and bottom left) and abdominal segments on the underside of the tail of Marron
(Cherax cainii) captured near the Kent Street Weir within the Canning River. Photos: Tim Storer (DoW).
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
26
Freshwater mussel population structure
Mean MHI was 60.3%, which is within the range reported for W. carteri (60-70%; McMichael &
Hiscock 1958). Length-frequency distributions of mussels surveyed in this study are presented
in Figure 12. Mussels in the Yule Brook site were the largest, dominated by individuals in the
70-75 mm shell length range followed by mussels in the Canning River sites, which was
dominated by individuals within the 60-70 mm size range. Average shell length of mussels
within Yule Brook was 71.74 mm, which was significantly larger than those within the Canning
River sites, which were 66.45 and 67.68 mm long at the Bickley Brook Confluence and
Homestead Park sites (F = 9.022, df = 347, P < 0.001). Average shell lengths of mussels within
the Canning sites were not statistically different (t = 1.443, df = 275, P = 0.448).
Very few smaller individuals (<40 mm) were recovered during the surveys, but several
small mussels were found amongst dense root mats of Swamp Paperbark trees (Melaleuca
rhaphiophylla) int the Canning River near Homestead Park, which suggests they may be a
favoured habitat for developing juveniles. Although these few small individuals suggest some
recent recruitment, the length frequency patterns of W. carteri within the study area suggests
that regular recruitment may not have occurred in recent years and the population is aging and
probably in decline, although we are uncertain of the age-at-length of the species within this
system, and would need to validate age with growth rates.
The influx of salt from the estuary appears to have completely annihilated W. carteri in
the Canning River to a point approximately 450 m above Royal Street Bridge. Mussel shells
measured downstream of this point are reflective of now locally extinct populations. Refuges
of freshwater tributaries and pools within this reach could still harbour survivors, but additional
surveys would need to be undertaken to determine whether this is the case.
Because no live mussels were observed in the UWR sites, obviously no investigation of
reproductive status could be initiated. Further upstream behind Fancote Park however, regular
sampling of W. carteri on a monthly basis since 2009 has revealed that roughly half of the
population is composed of females and half is composed of males; spawning occurs in late
winter; embryos are brooded to the glochidia stage and released with the onset of warmer
waters in late spring to early summer (between September and November to around early
December) (Klunzinger et al., unpublished data). This period is the most critical time in the
developing freshwater mussel’s life cycle when glochidia have a brief opportunity to contact
host fish; appearing later, the detached transformed juvenile mussels face the challenge of
finding suitable habitat, avoiding predation by other macroinvertebrates and fishes and
obtaining the necessary food supply and environmental conditions for survival (Walker 1981;
Walker et al. 2001; Strayer 2008). Worldwide, little is known about the juvenile stage of
freshwater mussels in wild populations (e.g. Strayer 2008); the same is true for south-west WA.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
27
Yule Brook
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
0
2
4
6
8
10
12
14
16
18
Canning River - near Homestead Park
Shell length (1 mm size classes)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
0
2
4
6
8
10
12
14
16
18
Bickley Brook - Canning River Confluence
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Nu
mb
er
of
mu
sse
ls
0
2
4
6
8
10
12
14
16
18
Figure 12 Length-frequency distributions of Westralunio carteri within the Canning River in
November 2011. Green bars represent live mussels and red bars represent dead, empty
mussel shells.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
28
Water quality
A comprehensive analysis of water quality over time and space is beyond the scope of this
study. Instead we will focus on key sampling points and issues associated with the death of
freshwater mussels within the Canning River catchment. In 2010-2011, an exceptionally low
rainfall in the winter and high tides the following summer caused estuarine waters to breach
the Kent Street Weir, resulting in a salt wedge which travelled upstream from the Canning
Estuary to at least the Royal Street Bridge (Meredith, pers. comm.). A mussel kill was reported
to the Swan River Trust by a number of river management staff from various agencies within
the locality on 22 February 2011 which was followed by water quality sampling by the Swan
River Trust and Department of Water. A sample of dead mussels was collected and delivered to
the Department of Fisheries by Swan River Trust staff for post-mortem examination. Results
showed that the specimens were autolytic, but no parasites were found. Although the species
was reported as ‘blue mussel’, this was apparently made in error and noted later, but no official
change to the reporting document was made (Meredith, pers. comm.). The correct
identification of the species was confirmed as Westralunio carteri (Klunzinger pers. comm. with
Meredith). Water quality measurements taken during this incident are presented in Table 2.
During this survey, all mussels near the Royal Street Bridge were dead, even though
some were previously alive in November 2010 and 24 February 2011 (Lymbery and Klunzinger
et al., unpublished data). The few freshwater mussels which may have remained alive along
the banks in February 2011, probably became salt affected shortly after sampling, as evidenced
by Swan River Trust water quality measurements the following day and the empty shells found
in this study. The data obtained from the Swan River Trust showed the importance of sampling
throughout the water column and at various depths. The freshwater mussels behind Fancote
Park in Kelmscott remain alive and reproductively fit where water quality is generally fresh
(<0.5 ppt), well oxygenated and probably low in algal concentrations. The low dissolved oxygen
near Royal Street during the late afternoon and supersaturation the following day may very
well have presented physiological stress in W. carteri. In other regions where they have been
studied, freshwater mussels are particularly sensitive to hypoxic and anoxic stress and can
result in death in severe cases (Walker 1981; Humphrey 1984; Sheldon & Walker 1989). The
low DO threshold for W. carteri is currently unknown.
The heavy salt concentrations from the 25 February 2011 sampling (Swan River Trust
data), was probably the leading cause of death in this system. Klunzinger et al. (2010) reported
an LD50 of ~2.0-3.0 ppt and an LD95 of ≥4.0 ppt for W. carteri, so the much higher
concentrations observed in February (≥11 ppt) would certainly have been lethal to the local
population.
From available data, within the Bannister Creek and Wungong River sites,
environmental variables alone do not explain the absence of W. carteri. If, at one time, W.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
29
carteri existed within the sites we surveyed, their disappearance could have been caused by
any number of factors, but we cannot speculate without historic data. The presence of
industrial, household and perhaps even agricultural chemicals within the waterways can be
detrimental to freshwater mussel populations (e.g. Strayer 2008). In other regions where they
have been studied, freshwater mussels are know to have been eliminated from a number of
anthropogenic toxins; the major contaminants include anoxia from domestic and industrial
wastes, acid mine drainage (Ortmann 1909; Neves et al. 1997), ammonia (Auspurger et al.
2003), chlorine and chlorination by-products (Goudreau et al. 1993), heavy metals (Naimo
1995), industrial chemical spills (e.g. Crossman & Cairns 1973; Sparks et al. 1999; USFWS 2002),
synthetic pesticides (Conners & Black 2004), polycyclic aromatic hydrocarbons (Weinstein &
Polk 2001) and unionised ammonia (Auspurger et al. 2003; Newton 2003; Mummert et al.
2003) to name a few.
Table 2. Water quality parameters associated with freshwater mussel deaths in the Canning River during February 2011.
Date Freshwater mussel status
Time Site GPS Temp. (°C)
Salinity (ppt)
pH DO (%)
Microalgae (No. cells/mL)
25 Oct 2010
Alive 1:00 PM Behind Fancote Park, Kelmscott
32°06'42"S 116°01'00"E
18.8 0.454 7.11 95.6 n/a
Nov 2010 Alive DATA NOT AVAILABLE
Royal St Bridge, 0.5 m from river bank
32°02'39"S 115°57'57"E
DATA NOT AVAILABLE n/a
24 Feb 2011
Alive 2:30 PM Behind Fancote Park, Kelmscott
32°06'42"S 116°01'00"E
25.6 0.117 7.66 63.9 n/a
Alive 3:00 PM Royal St Bridge, 0.5 m from river bank
32°02'39"S 115°57'57"E
28.8 0.097 7.12 30.9 n/a
25 Feb 2011
Dead 10:58 AM 50 m upstream Royal St Bridge
32°02'39"S 115°57'57"E
29.1 11.51 6.64 198.5 4,040,000
Dead 11:04 AM 100 m upstream Royal St Bridge
32°02'40"S 115°57'58"E
30.2 15.2 6.76 223.2 3,555,200
15 Oct 2011
Alive 2:00 PM Behind Fancote Park, Kelmscott
32°06'42"S 116°01'00"E
18.7 0.101 8.08 73.5 n/a
11 Nov 2011
Dead DATA NOT AVAILABLE
50 m upstream Royal St Bridge
32°02'39"S 115°57'57"E
DATA NOT AVAILABLE n/a
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
30
Conservation significance and recommendations
The number of dead freshwater mussels (W. carteri) found within the Canning River and lack of
live W. carteri within any of the UWR sites is cause for concern, particularly in light of the fact
that historic records show that the species’ was once present within these systems. Salinity is
probably the leading cause of death of freshwater bivalves in the Swan-Canning Catchments,
which has resulted in large range contractions since European settlement (Kendrick 1976;
Keighery et al. 2004; Klunzinger et al., unpublished data).
Many of the remaining populations of W. carteri are maintained by freshwater flows
and within dams along the Darling Scarp, which includes the Canning and Helena Rivers.
Smaller tributaries of the Swan River, including Bennet Brook, Jane and Susannah Brooks and
tributaries of Ellen Brook, such as Yalyal, Boorara and Lennard Brooks are maintained by
groundwater (Beatty et al. 2010b). As such, maintaining dam water levels, groundwater
reserves and discharge and environmental flow releases will become increasingly important
and more challenging as the climate becomes hotter and drier (e.g. Beatty et al. 2010a,b). In
heavily populated areas of south-east Asia such as Singapore, for example, freshwater flows
from rivers have been reduced to drinking water dams and are essentially the last remaining
native arks for populations of freshwater fauna (Clements et al. 2006), thus outlining the
importance of maintaining water quality and levels in dams. The use of chlorine in drinking
water supplies is a common treatment to prevent human ailments, but chlorination within
open water dams can have detrimental effects on wildlife, particularly sensitive fauna such as
freshwater mussels (Valenti et al. 2006). The effect of chlorine on W. carteri has never been
tested.
Dehydration has been shown to negatively impact W. carteri and some populations are
being lost from drought and de-watering (Klunzinger et al. 2011b). Sedimentation from
construction projects and erosion is another killer, which swallows populations of freshwater
mussels, clogging their siphons and leading to death in some areas (Jones & Byrne 2010;
Klunzinger et al., unpublished data). In some streams, for example, W. carteri is restricted to
thin edges (~20 cm wide) along stream banks while the stream channels are filling with coarse,
mobile sand (Beatty et al. 2010b). In rural areas, trampling from livestock has devastating
consequences for W. carteri (Jones & Byrne 2010; Beatty et al. 2010b).
The main issues concerning potential re-introduction of W. carteri into UWR sites are
salinity and sedimentation. If, at some stage, there may be an initiative to re-introduce the
species, sedimentation will need to be minimized and adequate habitat with sediments soft
enough for mussels to burrow, but stable enough so they stay in place will need to be secured.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
31
Maintaining riparian vegetation, in-stream macrophytes and woody debris in the rivers will
enhance native freshwater fish habitats which are necessary for the recruitment of W. carteri
and will provide structure and biodiversity necessary for a functioning ecosystem. An
investigation into the habitats necessary for juvenile W. carteri settlement and survival is also
necessary. Some decisions will need to be made on whether the Canning River and its
tributaries above Kent Street Weir will be managed as a freshwater river or as an extension of
the estuary. Indeed, the massive amounts of W. carteri which have been lost from summer-
time salt wedges will take many years to recover, if at all and captive rearing to boost numbers
may become necessary in the future.
In other UWR sites, pollutants such as industrial, agricultural and household chemicals
need to be prevented from entering the waterways and persistent contaminants, such as heavy
metals, will need to be monitored and mitigated. Toxicology on W. carteri to various chemicals
may initially be necessary to determine tolerances, but protocols for testing surrogate
organisms (i.e. those which closely match W. carteri in terms of physiological and
environmental tolerances) that have a shorter generation time and are more readily available
will need to be developed. More funding to answer basic questions about the life cycle,
population viability and abundance will be necessary to ensure the survival of the only endemic
freshwater mussel in south-western Australia. This mollusc may prove useful in the removal of
undesirable algae and nutrients within UWR sites in the future and is a vital component of a
functioning freshwater ecosystem. For the reasons outlined above, abatement of threats such
as sedimentation, salinity and contaminants will need to be addressed before considering re-
introduction and existing viable populations of W. carteri will require protection. A system-
wide assessment of the existing W. carteri populations within the Swan-Canning catchments is
necessary to determine the long-term viability of the species.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
32
References
Allen, G.R, Midgley, S.H. and Allen, M. (2002). Field guide to the freshwater fishes of Australia. Western Australian
Museum, Perth.
Ausgspurger, T., Keller, A.E., Black, M.C., Cope, W.G. & Dwyer, F.J. (2003). Water quality guidance for protection of
freshwater mussels (Unionidae) from ammonia exposure. Environmental Toxicology and Chemistry 22:
2569-2575.
Bauer, G. & Wächtler, K. (2001). Ecology and Evolution of the Freshwater Mussels Unionoida. Springer-Verlag, New
York.
Beatty, S.J. & Morgan, D.L. (2010). Teleosts, agnathans and macroinvertebrates as bioindicators of ecological
health in a south-western Australian river. Journal of the Royal Society of Western Australia 93: 65-79.
Beatty, S.J., Morgan, D.L., McAleer, F.J. & Ramsay, A.R. (2010a). Groundwater contribution to baseflow
maintains habitat connectivity for Tandanus bostocki (Teleostei: Plotosidae) in a south-western
Australian river. Ecology of Freshwater Fish 19: 595-608.
Beatty, S.J., Morgan, D.L., Klunzinger, M.W. & Lymbery, A.J. (2010b). Aquatic macrofauna of Ellen Brook and
Brockman River: Freshwater refuges in a salinised catchment. Centre for Fish & Fisheries Research
(Murdoch University), report to Ellen Brockman Integrated Catchment Group.
Clements, R., Koh, L.P., Lee, T.M., Meier, R. & Li, D. (2006). Importance of reservoirs for the conservation of freshwater molluscs in a tropical urban landscape. Biological Conservation 128: 136-146. Conners, D.E. & Black, M.C. (2004). Evaluation of lethality and genotoxicity in the freshwater mussel Utterbackia
imbecillis (Bivalvia: Unionidae) exposed singly and in combination to chemicals used in lawn care. Archives
of Environmental Contamination and Toxicology 46: 362-371.
Crossman, J. S. & Cairns, J. (1973) Aquatic invertebrate recovery in the Clinch River following hazardous spills and
floods. Research Bulletin of the Virginia Water Resources Research Center 63. Blacksburg, VA.
Davis, J. & Christidis, F. (1999). A Guide to Wetland Invertebrates of Southwestern Australia. Western Australian
Museum, Perth.
De Graaf, M., Beatty, S.J. & Molony, B.M. (2010). Evaluation of the recreational marron fishery against
environmental change and human interaction. Fisheries Research Report No. 211. D. Baxter & R. Larsen
(eds.). Department of Fisheries, Government of Western Australia, Perth.
DEC (Department of Environment and Conservation). (2011). Current Threatened and Priority Fauna Rankings.
Department of Environment and Conservation, Government of Western Australia. Available at
http://www.dec.wa.gov.au/management-and-protection/threatened-species/listing-of-species-and-
ecological-communities.html.
Goudreau, S., Neves, R. & Sheehan, R. (1993). Effects of wastewater treatment plant effluents on freshwater
mollusks in the upper Clinch River, Virginia, USA. Hydrobiologia 252: 211-230.
Humphrey, C. L. (1984). Biology and ecology of the freshwater mussel Velesunio angasi (Bivalvia: Hyriidae) in the
Magela Creek, Alligator Rivers region, Northern Territory. PhD Thesis, University of New England,
Australia.
IUCN (International Union for the Conservation of Nature). (2011). Mollusc Specialist Group 1996. Westralunio
carteri. IUCN Red List of Threatened Species. Version 2011.2. Available at www.iucnredlist.org.
Jones, H.A. & Byrne, M. (2010). The impact of catastrophic channel change on freshwater mussels in the Hunter
River system, Australia: a conservation assessment. Aquatic Conservation: Marine and Freshwater
Ecosystems 20: 18-30.
Keighery G. J., Halse S. A., McKenzie N. L., & Harvey M. S. (2004). A biodiversity survey of the Western Australian
agricultural zone. Western Australian Museum, Perth. Records of the Western Australian Museum
Supplement 67: 384pp
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
33
Kendrick, G.W. (1976). The Avon: faunal and other notes on a dying river in south-western Australia. The Western
Australian Naturalist 13: 97-114.
Klunzinger, M.W. (2011). Freshwater shrimp (Palaemonetes australis) may be involved in glochidia release from
the freshwater mussel Westralunio carteri. The Western Australian Naturalist 28: 61-65.
Klunzinger, M.W., Beatty, S.J. & Lymbery, A.J. (2010). Acute salinity tolerance of the freshwater mussel
Westralunio carteri Iredale, 1934 of south-west Western Australia. In: 17th
International Congress of
UNITAS MALACOLOGICA, World Congress of Malacology, 18-24 July 2010, Phuket, Thailand. Tropical
Natural History Supplement 3: 112 (Abstr.).
Klunzinger, M.W., Beatty, S.J., Morgan, D.L., Lymbery, R.A., Thomson, G.J. & Lymbery, A.J. (2011a). Discovery of a
host fish species for glochidia of Westralunio carteri Iredale, 1934 (Bivalvia: Unionoidea: Hyriidae). Journal
of the Royal Society of Western Australia 94: 19-23.
Klunzinger, M.W., Beatty, S.J. & Lymbery, A.J. (2011b). Freshwater mussel response to drying in the Lower Helena
Pipehead Dam and mussel translocation strategy for conservation management., Centre for Fish &
Fisheries Research (Murdoch University), report to Swan River Trust.
Lymbery, A., Lymbery, R., Morgan, D. & Beatty, S. (2008) Freshwater mussels (Westralunio carteri) in the
catchments of Geographe Bay, south-western Australia. Report prepared for the Water Corporation,
Western Australia. Fish Health Unit, Centre for Fish and Fisheries Research, Murdoch University.
Mayer, X., Ruprecht, J., and Bari, M. (2005). Stream salinity status and trends in south-west Western Australia.
Department of Environment Salinity and Land Use Impact Series, Report No. SLUI 38.
McMichael, D.F. & Hiscock, I.D. (1958). A monograph of the freshwater mussels (Mollusca: Pelecypoda) of the
Australian Region. Australian Journal of Marine and Freshwater Research 9: 372-507.
Morgan, D.L., Gill, H.S. and Potter, I.C. (1998). Distribution, identification and biology of freshwater fishes in south-
western Australia. Records of the Western Australian Museum Supplement No. 56: 1-97.
Morgan, D.L., Beatty, S.J., Klunzinger, M.W., Allen, M.G. & Burnham, Q.F. (2011). A Field Guide to Freshwater
Fishes, Crayfishes & Mussels of South-Western Australia. Published by SERCUL and Murdoch University
Freshwater Fish Group & Fish Health Unit, Perth, Western Australia.
Mummert, A.K., Neves, R.J., Newcomb, T.J. & Cherry, D.S. (2003). Sensitivity of freshwater mussels (Lampsilis
fasciola, Villosa iris) to total and un-ionized ammonia. Environmental Toxicology and Chemistry 22: 2545-
2553.
Naimo, T.J. (1995) A review of the effects of heavy metals on fresh-water mussels. Ecotoxicology, 4: 341-362.
Neves, R.J., Bogan, A.E., Williams, J. D., Ahlstedt, S. A. & Hartfield, P. W. (1997). Status of aquatic mollusks in the
southeastern United States: A downward spiral of diversity. In: G.W. Benz, & D.E. Collins, (eds.) Aquatic
Fauna in Peril: The Southeastern Perspective. Lenz Design and Communications: Decatur, GA.
Nevill, S.J. (2005). Guide to the Wildlife of the Perth Region. Simon Nevill Publications, Perth, Western Australia.
Newton, T.J. (2003). The effects of ammonia on freshwater unionid mussels. Environmental Toxicology and
Chemistry 22: 2543-2544.
Ortmann, A.E. (1909). The destruction of the fresh-water fauna in Western Pennsylvania. Proceedings of the
American Philosophical Society 48: 90-110.
Ponder, W.F. & Walker, K.F. (2003). From mound springs to mighty rivers: the conservation status of freshwater
molluscs in Australia. Aquatic Ecosystem Health and Management 6: 19-28.
Pen, L.J. (1999). Managing Our Rivers: A Guide to the Nature and Management of the Streams of South-West
Western Australia. Water and Rivers Commission, Eat Perth, Western Australia.
Sparks, D., Chafee, C. & Sobiech, S. (1999). Fish Creek restoration and preservation. Endangered Species Bulletin
24: 12-13.
SRT (Swan River Trust). (2009). Swan Canning Water Quality Improvement Plan. Swan River Trust (SRT), Perth,
Western Australia.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
34
Sheldon, F. & Walker, K.F. (1989) Effects of hypoxia on oxygen consumption by two species of freshwater mussel
(Unionacea: Hyriidae) from the River Murray. Australian Journal of Marine and Freshwater Research 40:
491-499.
Strayer, D.L. (2008). Freshwater Mussel Ecology: A Multifactor Approach to Distribution and Abundance. University
of California Press: Berkley.
Strayer, D.L. & Smith, D.R. (2003). A guide to Sampling Freshwater Mussel Populations. American Fisheries Society
Monograph 8, Bethesda, Maryland.
Tyler, M.J. & Doughty, P. (2009). Field Guide to Frogs of Western Australia, Fourth Ed. Western Australian Museum,
Welshpool, Western Australia.
United States Fisheries and Wildlife Service (USFWS). (2002). Certus chemical spill natural resource damage
assessment: Initial restoration and compensation determination plan. Available at:
http://unionid.smsu.edu/Documents/Draft.Certus.RCDP.pdf.
Valenti, T.W., Cherry, D.S., Currie, R.J., Neves, R.J., Jones, J.W., Mair, R. & Kane, C.M. (2006). Chlorine toxicity to
early life stages of freshwater mussels (Bivalvia: Unionidae). Environmental Toxicology and Chemistry 25:
2512-2518.
Vaughn, C.C. & Hakenkamp, C.C. (2001). The functional role of burrowing bivalves in freshwater ecosystems.
Freshwater Biology 46: 1431-1446.
Walker, K.F. (1981). Ecology of freshwater mussels in the River Murray. Australian Water Resources Council,
Canberra.
Walker, K.F. (2004). A Guide to the Provisional Identification of the Freshwater Mussels (Unionoida) of Australasia.
Murray Darling Freshwater Research Centre: Albury.
Walker, K.F., Byrne, M., Hickey, C.W. & Roper, D.S. (2001). Freshwater mussels (Hyriidae) of Australia. In: Ecology
and Evolution of the Freshwater Mussels Unionoida. G. Bauer & K. Wächtler (eds). Springer, Berlin.
Weinstein, J.E. & Polk, K.D. (2001). Phototoxicity of anthracene and pyrene to glochidia of the freshwater mussel
Utterbackia imbecillis. Environmental Toxicology and Chemistry 20: 2021-2028.
Widarto, T.H. (1996). Some aspects of reproductive biology of freshwater mussels living in a tropical area. Hayati 3:
21-25.
Wilson, S. & Swan, G. (2010). A Complete Guide to Reptiles of Australia. New Holland Publishers, Sydney.
BASELINE SURVEY OF FRESHWATER MUSSEL POPULATIONS FOR THE URBAN WATERWAYS RENEWAL PROJECT
35
Appendix
Freshwater mussel (Westralunio carteri) densities observed within the survey quadrats during this study.
River Name Site Quadrat
No.
Density (No.
mussels/m2)
Status River
Name
Site Quadrat
No.
Density (No.
mussels/m2)
Status
Canning River
Near Bickley Brook Confluence
1 1 Dead Yule Brook
Near SERCUL
1 1 Dead
“ “ 2 0 “ “ 2 0
“ “ 3 0 “ “ 3 0
“ “ 4 20 Dead “ “ 4 0
“ “ 5 65 Dead “ “ 5 2 Dead
“ “ 6 16 Dead “ “ 6 4 Dead
“ “ 7 4 Dead “ “ 7 2 Dead
“ “ 8 7 Dead “ “ 8 0
“ “ 9 23 Dead “ “ 9 1 Dead
“ “ 10 4 Dead “ “ 10 0
“ “ 11 5 Dead “ “ 11 0
“ “ 12 14 Dead “ “ 12 0
“ “ 13 0 “ “ 13 0
“ “ 14 1 Dead “ “ 14 0
“ “ 15 1 Dead “ “ 15 0
“ “ 16 2 Dead “ “ 16 15 Dead
“ “ 17 0 “ “ 17 0
“ “ 18 0 “ “ 18 0
“ “ 19 0 “ “ 19 0
“ “ 20 0 “ “ 20 0
Canning River
Near Homestead Park
1 44 (41 Live)
(3 Dead)
“ “ 21 0
“ “ 2 48 Live “ “ 22 0
“ “ 3 8 Live “ “ 23 5 Dead
“ “ 4 0 “ “ 24 1 Dead
“ “ 5 0 “ “ 25 0
“ “ 6 0 “ “ 26 2 Dead
“ “ 7 0 “ “ 27 4 Dead
“ “ 8 3 Live “ “ 28 2 Dead
“ “ 9 7 Live “ “ 29 0
“ “ 10 19 (18 Live)
(1 Dead)
“ “ 30 1 Dead
top related