The diversity of benthic macroinvertebrates within the creeks of the Manly Dam Catchment - Melody Fong Tida Nou
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The diversity of benthic
macroinvertebrates within the creeks of
the Manly Dam Catchment
Melody Fong
Tida Nou
Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
CONTENTS
Abstract…………………………………………………………………….3
1.0 Introduction………………………………………………………....….3
1.1 Background……………………………………………….….…3
1.2 Aims and Objectives………………………………………..…..5
2.0 Materials and Methods……………………………………………..…..6
2.1 Study Area…………………………………………………..…..6
2.2 Sample Methods……………………………………………..….6
2.3 Sample Sites…………………………………………………….7
2.4 Macroinvertebrate Identification…………………………….....11
2.5 Reference Collection and Photomicroscopy………………...…11
2.6 Water Quality Assessment……………………………….…….11
2.7 Numerical Analysis…………………………………………….12
2.8 Comparison with 2000 study…………………………………..12
3.0 Results and Discussion………………………………………………...13
3.1 Physical-Chemical Parameters…………………………………13
3.2 Diversity of Macroinvertebrates………………………………..14
3.3 Macroinvertebrates and Water Quality………………………...15
3.4 Diversity Indices……………………………………………….18
3.5 Comparison with 2000 study…………………………………..20
4.0 Limitations to Study…………………………………………………..22
4.1 Sample sites……………………………………………………22
4.2 Time constraints………………………………………...……..22
4.3 Taxonomic discrimination and ecological requirements
of macroinvertebrates………………………………………….22
4.4 Effectiveness of macroinvertebrates as biomonitors………….22
4.5 Sampling techniques…………………………………………..23
4.6 Numerical analysis…………………………………………….23
5.0 Conclusion…………………………………………………………....24
6.0 Recommendations and Suggestions……………………………….....24
Acknowledgments and References………………………………………25
Appendices……………………………………………………………….27
2Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Abstract
The diversity of benthic macroinvertebrates in the creeks within the Manly Dam
Catchment was studied using the commonly used kick-sample method. The primary
aim of the project was to record the diversity of macroinvertebrates of the Manly Dam
catchment, to provide baseline data from which future comparisons could be made in
relation to the effects of surrounding land uses on the water quality within the
catchment. Laboratory identification indicated that 39 families from 13 orders were
collected from 12 sites during the survey. Assessment of the impacts of the land uses
throughout the catchment on macroinvertebrate diversity was difficult due to the
limited number of suitable sampling sites. This study indicates that the golf course
appears to have little effect on the macroinvertebrate diversity, which may reflect its
improved management practices. An assessment of water quality in the catchment
using Streamwatch methods indicates that the water quality at the sample sites ranges
from fair to good. It is proposed that monitoring of water quality in the catchment
continues, and that biological monitoring be considered to complement the physical
and chemical measurements, to provide an additional aid in detecting changes in
water quality and environmental condition within the Manly Dam catchment.
1.0 Introduction
1.1 Background
The Manly Dam catchment is located 20 kilometres north of Sydney and covers an
area of about 485 hectares. The catchment comprises natural bush, residential areas,
urban and residential development, light industry and recreational areas. The Manly
Dam catchment is unique in that supports the only population of the endangered
climbing galaxias Galaxias brevipennis in the metropolitan area (Huxley, 2001).
In 1892 the Manly Municipal Council commissioned the construction of the dam on
Curl Curl Creek, in order to supply water to residents of the area (Crewe et al, 2000).
Curl Curl Creek was selected as it is the major drainage system within the catchment,
with all the streams in the northern part of the catchment draining into it (Crewe et al,
2000). The dam wall was raised three times to increase its water storage capacity as
demand increased as a result of the growing population. This resulted in a reduction in
the natural flows of Curl Curl Creek (Crewe et al, 2000). In 1929, the dam could no
longer meet residential demand and water was delivered from the Pymble Reservoir
(Crewe et al, 2000). In 1939, the Manly Warringah War Memorial Park was
designated as a reserve for public recreation and the dam ceased to be a part of the
water supply system in 1942 (Boey, 1997). Today, the reserve contains about 75% of
the catchment, covering an area of about 370 hectares and offers a variety of
recreational activities such as bushwalking, picnicking, swimming, sailboarding,
fishing, cycling and water skiing (Boey, 1997).
The northern part of the catchment is drained by many small streams which are
mostly ephemeral (Boey, 1997). There are also numerous ephemeral streams feeding
directly into the dam. There are a variety of anthropogenic activities that influence the
ecology of the Manly Dam catchment. These include the adjacent Wakehurst Golf
3Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Course, the presence of two former landfill sites within the catchment, residential and
urban development and light industry, which surround the catchment. These areas
represent sources of water pollution, which affect water quality within the catchment.
Previous studies have shown that Curl Curl Creek is a significant source of nutrient
pollution, probably due to runoff from industries located in the upper catchment
(Boey, 1997). The residential areas in the northern part of the catchment also
represent a source of pollutants, chiefly through surface runoff and stormwater
entering the catchment. The Wakehurst Golf Course and its activities has been
recognised as a major source of nutrients and other pollutants in the catchment (Boey,
1997). Ecological impacts of the golf course include erosion of soils, increased runoff,
nutrient and pesticide export, alteration of water tables, and removal of natural
vegetation (Boey, 1997). Runoff from the golf course has in the past caused
eutrophication and algal blooms within the dam. The recent Ardel/Madison
development in the upper catchment, consisting of a 32-lot residential site on former
Crown land at Allambie Heights is also a cause of concern in terms of its impacts on
the water quality of Curl Curl Creek. The developer has taken a number of
precautions to prevent the degradation of water quality in Curl Curl Creek, including
the construction of a large settlement tank to filter runoff from homes.
The effects of such pollutant impacts are degradation of water quality of Curl Curl
Creek and its tributaries (Boey, 1997). This in turn affects water quality of the
receiving waters of Manly Dam and has consequences for its environmental values
(Boey, 1997). The deterioration of water quality in Curl Curl Creek and its tributaries
may adversely affect aquatic biota. Boey (1997) states that macroinvertebrate and fish
communities may be affected in terms of their food source and habitat alterations,
resulting in changes along the food chain. For instance, if macroinvertebrate
communities are altered, in terms of changes in species composition or decreasing
species richness, higher animals such as fish and birds may have their food source
eradicated (Boey, 1997).
One method of assessing water quality is the use of biological monitoring. Biological
monitoring can be broadly defined as the use of organisms (both plant and animal) to
assess environmental quality (Bennison et al, 1989). In Europe and North America
aquatic macroinvertebrates have been used for decades in the assessment of water
quality and as a supplement to the detection of pollution by the chemical analysis of
the water samples (Bennison et al, 1989).
Freshwater macroinvertebrates, the subject of this study, are a group of animals
without backbones, sufficiently large enough to be seen with the naked eye (>0.5mm)
and live for at least a part of their life cycle in freshwater (Bennison et al, 1989).
Macroinvertebrates represent ideal integrators between the microorganisms that
dominate nutrient cycling and the fish that are often the product of interest in aquatic
systems (Cummins, 1992). The major macroinvertebrate groups include the worms,
molluscs (snails and bivalves), crustaceans (shrimps and yabbies) and a wide range of
insects (larvae and adults) (Bennison et al, 1989). In Australia, there is limited
knowledge on the taxonomy, life histories and ecological requirements of the animals
that exist in Australia’s marine and freshwater ecosystems.
4Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Benthic macroinvertebrates offer many advantages as biomonitors (Rosenberg and
Resh, 1993). Firstly, they are ubiquitous, and are therefore affected by environmental
perturbations in aquatic systems. Secondly, the large volume of species offers a
spectrum of responses to environmental stresses. Thirdly, their essentially sedentary
nature allows effective spatial analyses of pollutant or disturbance effects. Fourthly,
they have long life cycles compared to other groups, which allows elucidation of
temporal changes caused by perturbations (Rosenberg and Resh, 1992). From an
ecosystem perspective, macroinvertebrates represent ideal integrators between the
microorganisms that dominate nutrient cycling and the fish that are often the product
of interest in aquatic systems (Cummins, 1992). Therefore, macroinvertebrates act as
continuous monitors of the waters they inhabit (Rosenberg and Resh, 1993).
Additionally, different groups of macroinvertebrates have different tolerances to
pollution, which means they can serve as useful indicators of water quality (Williams
and Feltmate 1992).
Biological water assessment must become an important tool of resource managers
responsible for protecting aquatic systems, as only these biological techniques can
demonstrate that the integrity of the ecosystem is being maintained (ANZECC, 1992).
However, it is noted the development of biological assessment techniques applicable
to aquatic ecosystems is still in its infancy in Australia (ANZECC, 1992).
The following survey of the diversity of macroinvertebrates in the creeks around the
Manly Dam catchment was carried out over three-month period. Macroinvertebrates
were also considered in terms of their value as biological monitors and were used to
assess the water quality of the creeks sampled.
1.2 Aims and Objectives
The aim of this study is to assess the diversity of benthic macroinvertebrates in
various creeks within the Manly Dam Catchment. The specific objectives are to:
• provide a baseline qualitative assessment of the benthic macroinvertebrates
present in the creeks of the Manly Dam catchment
• use biological monitoring methods to assess the water quality within the
Manly Dam catchment
• provide a reference collection of benthic macroinvertebrates from the Manly
Dam catchment for future ecological studies.
5Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
2.0 Materials and Methods
2.1 Study Area
The Manly Dam catchment was the area of study for this survey, with particular focus
on the creeks or streams around the catchment. There are numerous unnamed streams,
many of which are ephemeral, in the Manly Dam catchment. The streams in the
northern part of the catchment drain into Curl Curl Creek, which flows into Manly
Dam. Curl Curl Creek is 1.6km long, and contains alternating riffle/pool sequences
(Boey, 1997). The catchment has an underlying geology of Hawkesbury sandstone.
2.2 Sampling Methods
Sampling was carried out over 5 days in dry weather conditions. Sampling dates and a
brief description of weather conditions is given in Table 1.
Table 1: Sampling dates and weather conditions.
Sampling Date Weather conditions
7/9/01 Overcast, maximum temp 21°C
10/9/01 Fine, some clouds, maximum 21°C
17/9/01 Overcast, slight breeze, possible showers,
maximum 20°C
21/9/01 Fine, maximum 23°C
29/9/01 Overcast, expected showers (rained after
sampling was complete)
Twelve sites were selected within the Manly Dam catchment, based on their
suitability for macroinvertebrate collection (in terms of site accessibility, depth, width
and flow of the creeks). The following physical and chemical parameters -
temperature, dissolved oxygen (DO) and pH were measured at each sample site to
assess the water quality, using the equipment listed in Table 2.
Table 2: Equipment used to measure physical-chemical parameters
Physical-chemical Equipment Units
parameter
Temperature YSI Model 55 Handheld °C
Dissolved Oxygen and
Temperature System
Dissolved oxygen (DO) YSI Model 55 Handheld mg/L
Dissolved Oxygen and
Temperature System
pH WTW pH 90 Series Meter
A site description was conducted to describe characteristics of each site, such as the
type of substrate, vegetation coverage, surrounding land use and the width and depth
of the sampled creek. Additionally, photographs were taken at each site to allow
replication in future studies if required. Two samples at each site were conducted at
6Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
each site using the kick and shuffle method. This method involves facing downstream
and placing a 250µm mesh dipnet in front of the operator, with the bottom of the net
against the substratum. The substratum upstream of the net is then vigorously
disturbed with the feet and dislodged invertebrates flow into the net (Mason, 1996).
Samples were sorted in the field as the macroinvertebrates were more easily detected
while they were still alive. The samples of macroinvertebrates were preserved in 10%
formalin solution and then taken back to the laboratory for identification.
Identification was carried out to family level.
2.3 Sample Sites
The initial aim in selecting the sample sites was to select sites affected by the major
landuses in the catchment (light industrial, recently developed, golf course,
residential) in order to determine whether there were any significant differences
between macroinvertebrate diversity in streams impacted by the various landuses.
A reconnaissance survey was conducted to identify appropriate sample sites affected
by various land uses (residential, light industrial, golf course and a relatively pristine
area). During the course of this survey, we found that there was only a limited number
of sites within various streams that were appropriate for macroinvertebrate sampling.
Many of the streams have a sandstone substrate, which represent poor habitat for
macroinvertebrates. We were unable to sample for macroinvertebrates at the recently
developed Ardel/Madison site for this reason. Furthermore, many streams were in low
flow and others were extremely narrow and could not be sampled. Therefore, we
could not use a random stratified sampling method and had to adopt an approach to
sampling based on ideal site characteristics for macroinvertebrate sampling.
The study area with some sample sites indicated is illustrated in Figure 1.
7Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Figure 1: The study area consisting of the Manly Dam catchment and selected sample
sites (•).
8Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
There was a total of 12 sample sites selected for sampling (10 major sites, with 2
samples taken at sites 8 and 10 on different substrates). Sample site descriptions and
photographs are given in Table 3.
Table 3: Site descriptions and photographs.
Site Site Description Photo Image of Site
Number
1 Along Nature Trail in
Section 2. Fern gully with
80% vegetation coverage.
Stream substrate mainly
leaf litter, some gravel and
sand. Stream width 1m,
length 2m, depth 0.2m .
2 Along Nature Trail in
Section 2. Slow flowing
stream reach with
gravel/leaf litter substrate.
Stream width 1.5m, length
1-4m, depth 0.2-0.3m.
Mainly native vegetation
including ferns, grasses,
eucalypts and banksias.
3 Tributary of Curl Curl
creek in upper catchment
with gravel/leaf litter
substrate. Stream width
3m length 2.5m, depth
0.5m.
4 Slow flowing section of
Curl Curl Creek on
exposed rocky outcrop,
with gravel substrate.
Stream width 2m, length
4m, depth 0.3m.
5 Small pool along Curl Curl
9Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Creek in upper catchment
with macrophytes on
sandstone substrate.
Stream width 2m, length
1.5m, depth 0.4m.
6 Slow flowing section of
Curl Curl Creek. Substrate
consists of leaf litter and
gravel, also thin layer of
macrophytes on sandstone
base. Stream width 2m,
length 2.5m, depth 0.4m.
7 Slow slowing section of
Curl Curl Creek south of
second waterfall. Substrate
consists of leaf litter
covering sandstone
platform, some
macrophytes present.
Stream width 6m, length
10m, depth 0.6m.
8a Tributary of Curl Curl
Creek. Substrate consists
largely of leaf litter.
Stream width 1.5m, length
8m, depth 0.5m.
8b Tributary of Curl Curl
Creek, downstream from
Site 8a. Substrate consists
largely of gravels
overlaying sandstone.
9 Creek in Section 4 coming
down from Wakehurst
Golf Course. Substrate
largely macrophytes on
sandstone base. Stream
width 2m, length 3m,
depth 0.5m. Sample was
taken at mouth of creek
entering Manly Dam.
10a Slow-flowing creek in
10Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
north-east part of
catchment down from
Circuit Track. Sample
taken near where stream
enters Manly Dam.
Substrate consists of leaf
litter, gravel and
macrophytes. Stream
width 1.5m, length 2m,
depth 0.45m.
10b Slightly downstream from See photograph above
Site 10a. Substrate mainly
leaf litter and mud.
2.4 Macroinvertebrate Identification
One of the objectives of this study was to identify the macroinvertebrate fauna in the
Manly Dam catchment. However, as stated in Bennison et al (1989), much of
Australia’s invertebrate fauna is either undescribed, or insufficiently characterised to
permit ready identification to the species level. However, recent work in both
freshwater and marine systems suggests that identification to higher taxonomic levels
(e.g family) may detect almost all the patterns detected by species-level identification
and at far lower cost (ANZECC, 1992).
Specimens from this study were identified to the lowest practical limit (family level)
using various Australian macroinvertebrate identification keys. Any incomplete
specimens were discarded during sorting. The identification of macroinvertebrates
was verified by Dr. Richard Lim.
2.5 Reference collection and photomicrography
The University of Technology, Sydney has commenced the establishment of a Manly
Dam macroinvertebrate reference collection for future ecological studies. This
involved placing specimens in airtight specimen tubes containing 70% ethanol.
Additionally, the reference collection was photographed using photomicroscopy
techniques to establish an electronic database of the macroinvertebrates collected in
the Manly Dam catchment.
2.6 Water Quality Assessment
The Streamwatch Stream Pollution Index and Stream Quality rating calculation table
were used to obtain a general idea of the water quality in each of the sample sites.
This rating is based on the principle that the presence of more sensitive
macroinvertebrates and higher diversity of macroinvertebrates are indicators of good
quality water. The water quality of each site was assessed using the Stream Pollution
Index, and are rated as poor, fair, good and excellent accordingly (see Appendix 2)
11Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
2.7 Numerical Analysis
The results from the study were numerically analysed using the Cluster program,
which assesses the percentage of faunal similarity between sites using various indices
of similarity. In this study, two indices were used to classify the sample sites on the
basis of the composition of the taxa at each site. The indices used were as follows:
Sorensen’s Index (Sorenson, 1948):
S= 2c (a+b) –1
where a and b are the number of taxa (families) in communities A and B respectively,
and c is the number of families common to both communities and S is the percentage
of faunal similarity.
Jaccard’s Index (Jaccard, 1912)
S= j/r x 100
where j is the number of taxa found in both samples and r is the number of taxa found
in only one sample or the other and S is the percentage of faunal similarity.
2.8 Comparison with previous studies
The results obtained by this study were compared to those obtained by a similar study
undertaken in 2000. However, it must be noted that as a result of different sampling
sites and analyses, the results are not directly comparable. The 2000 study was a
quantitative study, in which 5 sites within the upper catchment were sampled and the
results statistically analysed using the non parametric Kruskal-Wallis test in addition
to assessing water quality using the BMWP (Biological Monitoring Working Party)
score. In the 2001 study, the aim was to sample more extensively around the
catchment to provide a baseline specimen list of the macroinvertebrates present in the
creeks within the catchment. A brief comparison between the results of the 2000 and
2001 studies was conducted to consider the differences in diversity between the
studies of the two years.
12Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
3.0 Results and Discussion
3.1 Physical-Chemical Parameters
The physical-chemical parameters considered in this study were water temperature,
pH and dissolved oxygen. The results for each of these parameters are listed in Table
4.
Table 4: Physical-chemical parameters of each sample site
Site Water pH Dissolved oxygen
temperature (°C) (mg/L)
1 14.1 5.19 2.5
2 14.0 5.37 3.8
3 13.6 7.29 9.2
4 14.6 7.23 9.48
5 16.9 5.62 7.92
6 15.9 7.31 7.78
7 14.6 7.08 7.85
8a 15.6 5.33 4.72
8b 15.6 5.33 4.72
9 22.3 7.43 8.6
10a 16.8 4.86 4.16
10b 16.8 4.86 4.16
A number of factors - biotic, chemical and physical, influence the distribution and
abundance of macroinvertebrates. General physical-chemical conditions may well
determine the large-scale distribution patterns of macroinvertebrate stream species
(Cummins, 1992). However, there is little correlative evidence to demonstrate that
this is the case, and Cummins (1992) suggested that macroinvertebrate distribution
and abundance is actually controlled by other factors, such as food quality/quantity,
which itself is more directly related to the physical-chemical parameter.
The effects of physical-chemical parameters on aquatic systems are discussed in the
ANZECC guidelines for water quality. Water temperature has a substantial effect on
the functioning of aquatic systems and the physiology of the biota (ANZECC, 1992).
However, there is relatively little information available on the thermal tolerances of
Australian aquatic organisms and their responses to temperature change (ANZECC,
1992). Water temperatures in the Manly Dam catchment varied from 13.6°C to
22.3°C, however due to the lack of information, we cannot ascertain the impact of
water temperature on macroinvertebrate diversity.
The pH of aquatic systems is important in that it can affect the toxicity of pollutants.
ANZECC (1992) guidelines recommend that the pH of freshwater should fall in the
range 6.5 to 9.0. pH values recorded at 5 of the 12 sites were below these guidelines.
This may be attributable to the decaying of organic matter in these waters which may
contribute to the more acidic nature of the waters, or possibly as a result of problems
with the pH meter.
13Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
According to ANZECC (1992) guidelines, dissolved oxygen should not normally be
permitted to fall below 6mg/L, this being determined over at least one diurnal cycle. It
must be noted that in this study, only a single measurement for each parameter was
taken. The ANZECC guidelines state that spot measurements of dissolved oxygen are
not particularly useful. The full diurnal range of dissolved oxygen must be known
before the data can be interpreted, and preferably the diurnal range over a number of
days accounting for different weather conditions (ANZECC, 1992). However, it can
be noted that a reduction in dissolved oxygen concentration in water reduces the
physiological efficiency of fish and non-air breathing invertebrates (ANZECC, 1992).
There are no known published studies to date on the effects of dissolved oxygen on
Australian aquatic invertebrates, so we cannot determine if this factor influenced
macroinvertebrate diversity in the Manly Dam catchment.
According to Cummins (1992) the primary parameters determining micro-distribution
patterns are the availability of food, nature of the sediments and current flow,
excluding various degrees of human perturbation which may result in abnormally
high light intensities, low oxygen levels or increased nutrient loads. In this study,
limited suitable sampling sites meant that it was not possible to keep the substrate, on
which samples were taken, uniform throughout the catchment (see section 2.2). This
was one source of variation, which is likely to have contributed to the different
diversity of macroinvertebrates between sample sites.
3.2 Diversity of Macroinvertebrates
A total of 39 families from 13 orders was recorded in the macroinvertebrate survey of
the creeks within the Manly Dam catchment. The complete specimen list is given in
Appendix 1. The number of families found in various aquatic insect orders collected
during the survey is shown in Table 5. The majority of macroinvertebrates were insect
larvae and nymphs, but others included crustaceans, molluscs and oligochaetes.
Table 5: The number of families in the major insect orders collected in the Manly
Dam catchment.
Order Common Name No. of families
Blattodea (?) Cockroaches 1
Coleoptera Beetles 7
Diptera True flies 6
Ephemeroptera Mayflies 3
Hemiptera True bugs 2
Hydracarina Water mites 5
Megaloptera Alderflies 1
Odonata Dragonflies and 5
damselflies
Trichoptera Caddis flies 3
The taxonomic diversity between sites displayed considerable variation, as shown in
Figure 2 below.
14Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
14
12
10
Number of families
8
6
4
2
0
1 2 3 4 5 6 7 8a 8b 9 10a 10b
Site
Figure 2: Comparison of macroinvertebrate family diversity between sample sites.
The lowest diversity (3 families) was recorded at Site 10a, and the highest at Site 3
(13 families). The sites varied considerably in terms of their physical-chemical
parameters and site characteristics including substrate. Site 3 was a relatively pristine
site in the northern catchment, and was probably most minimally affected by human
perturbation of all the sample sites. This is attributable to its location in the upper
catchment furthest from anthropocentric impacts. This creek feeds into Curl Curl
Creek. Interestingly, the sample site containing the second-highest diversity (12
families) was located in Section 4, coming down from Wakehurst Golf Course. This
relatively high diversity reflects the considerable improvement in the golf course
management practices, as demonstrated by the researchers studying run-off from the
golf course. Site 10a was also located in the northern part of the catchment. However,
the low diversity at this site is most likely a result of the limited habitat availabilities
at this site. Another factor that may have contributed to the relatively low
macroinvertebrate diversity at this site is food availability. The site was a slow-
flowing creek, which fed directly into Manly Dam, and the substrate consisted largely
of decaying organic matter overlaying a muddy base.
3.3 Macroinvertebrates and Water Quality
The results obtained using the Streamwatch Stream Quality Rating calculation are
shown in Table 6.
15Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Table 6: Streamwatch water quality rating of the twelve sample sites.
Sample Site Streamwatch water quality rating
1 Fair
2 Fair
3 Fair
4 Poor
5 Fair
6 Good
7 Good
8a Good
8b Good
9 Good
10a Poor
10b Poor
Note: this calculation does not include the order Megaloptera.
It must be noted that in this case, the Streamwatch results do not necessarily reflect
the quality of the water in the catchment. Streamwatch surveys generally involves
sampling of larger streams than those present in the Manly Dam catchment. The
“poor” rating at Sites 10a and 10b is a result of the low habitat availabilities at these
sites, which in turn yielded low macroinvertebrate diversity results. Site 4 has rated
poorly by the Index due to the lack of sensitive macroinvertebrates at this site. Table 7
below shows the Streamwatch guidelines for macroinvertebrates and their relative
sensitivity to water quality. ‘Very sensitive’ macroinvertebrates are defined as those
that are only found in streams with good water quality. ‘Sensitive’ animals are usually
only found in streams with good or medium water quality. ‘Tolerant’ animals can be
found across a range of water quality in streams, but can live in poor-quality water.
‘Very tolerant’ animals can be found in water of poor to good water quality, but are
usually the most abundant group in streams with poor quality water (Streamwatch:
Melbourne Parks and Waterways, 1995).
Table 7: Streamwatch designated sensitivities of macroinvertebrates to water
pollution. Those denoted with an asterisk (*) were found during this survey.
Very sensitive Sensitive Tolerant Very tolerant
Stonefly nymph Freshwater mussel Nematodes Mosquito larvae
Freshwater Caddisfly Larvae* Hydra Midge larvae*
yabby/crayfish
Mayfly nymph* Damselfly nymph* Beetle larvae* Fly larvae*
Dragonfly nymph* True bugs* Aquatic earthworm
Freshwater shrimp* Beetles* Blood worm*
Water mites * Leeches
Freshwater Freshwater snails*
sandhopper
Freshwater slater Flatworm*
16Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Mayflies (Order Ephemeroptera) were recorded from 7 of the 12 sites. These are
considered to be very sensitive to water pollution. Their presence at more than half
the sites is indicative of good water quality at these sites. The sensitive
macroinvertebrates – caddis flies and riffle beetles were also recorded at a high
proportion of the sample sites, with caddis flies present at 75% of the sites. One riffle
beetle was found at site 3. The presence of very sensitive and sensitive
macroinvertebrates in the Manly Dam catchment is encouraging, and may be a
reflection of the improved golf course management practices (at Site 9). However, as
we could not sample below the recently developed Ardel/Madison site, we are unable
to provide a biological perspective on the water quality in this area.
17Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
3.4 Diversity Indices
The results of the Cluster analyses are shown in Figures 3 and 4 below.
Percentage faunal similarity
Figure 3: Dendrogram of Cluster analysis using Sorensen’s Index of Similarity.
18Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Percentage faunal similarity
Figure 4: Dendrogram of Cluster results using Jaccard’s Index of Similarity
The cluster analyses using the Sorensen’s and Jaccard’s indices yielded very similar
results. Both indices indicate that the sites 2 and 8b are the most similar to each other
in terms of macroinvertebrate diversity, with Sorensen’s index indicating 77% and
Jaccard’s 63% similarity between these sites. Examination of the raw data (see
Appendix 1) shows that these sites are relatively low in diversity, but have a number
of taxa in common. Additionally, these sites had similar pH values and substrates,
which may have contributed to the similarity in terms of the macroinvertebrate
communities they support. Sites 7 and 9 were also shown to display similar
macroinvertebrate diversity (70% by Sorensen coefficient, 54% by Jaccard’s).
Interestingly, Site 7 was located along Curl Curl Creek whereas Site 9 was located at
the mouth of the creek coming down from Wakehurst Golf Course. These sites
possessed the same substrates (varying degrees of macrophyte cover on sandstone),
which is a possible reason for the faunal similarity between these sites.
19Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
3.5 Comparison with 2000 study
Table 8 provides a comparison between the 2000 and 2001 macroinvertebrate studies
in the Manly Dam catchment.
Table 8: Comparison between 2000 and 2001 macroinvertebrate studies of the Manly
Dam catchment.
Specimen list: 2000 study Specimen list: 2001 study
Coleoptera Coeloptera
Gyrinidae Curculionidae
Dytiscidae
Helminthidae
Hydrophilidae
Limnichidae
Psephenidae
Diptera Diptera
Chironomidae Chironomidae
Culicidae
Syrphidae
Tabanidae
Tipulidae
Unknown
Ephemeroptera Ephemeroptera
Caenidae Baetidae
Leptophlebiidae Caenidae
Siphlonuridae Leptophlebiidae
Hemiptera Hemiptera
Notonectidae Coryxidae
Notonectidae
Odonata Odonata
Aeshnidae Aeshnidae
Corduliidae Corduliidae
Gomphidae
Hemicorduliidae
Megapodagrionidae
Other Other specimens(order/class) Family/phyla
Mollusca Decapoda Atyidae
Oligochaetae Gastropoda Lymnaeidae
Physidae
Oligochaetae
Turbellaria Tricladida
Megaloptera
Corydalidae
Hydracarina
Morphospecies 1
Morphospecies 2
Morphospecies 3
Morphospecies 4
Morphospecies 5
20Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Trichoptera
Economidae
Hydroptilidae
Leptoceridae
Blattodea (?)
Dictyoptera
The considerable differences in the results obtained in 2000 and those obtained in
2001 are attributable to the differences in sampling methods between the two studies.
Firstly, a higher number of sites were sampled in 2001 (5 sites in 2000, 12 sites in
2001). Secondly, an attempt was made to sample wherever possible within the
catchment in 2001, whereas the 2000 study concentrated on the upper catchment. This
resulted in a considerably higher diversity of macroinvertebrates being observed in
2001.
21Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
4.0 Limitations to Study
4.1 Sample Sites
In this study we were restricted to sampling pools due to the general absence of riffle
zones. Previous studies have shown that riffle zones of streams support substantially
higher macroinvertebrate densities (Scullion et al, 1982). Some species are exclusive
to riffle areas, while others are particularly associated with pool areas (Scullion et al,
1982). Higher densities of chironomids and oligochaetes, and lower densities of
ephemeropterans, trichopterans and simuliids have been reported in pool areas
(Scullion et al, 1982). A likely consequence of the reduced flows of Curl Curl Creek
due to the construction of Manly Dam is the reduction in the number of riffle zones
along the creek. It is possible that macroinvertebrate diversity may have been higher
prior to the construction of the dam, but this is impossible to establish as no known
previous studies were conducted.
Furthermore, it is acknowledged that macroinvertebrate taxon richness in small
streams may be limited by low flow (even drying up), lower habitat diversity and
greater thermal constancy (Lenat and Barbour, 1990). The streams in the Manly Dam
fit this description, so it is not surprising that some sites exhibited low
macroinvertebrate diversities. Another limitation was the lack of accessibility to many
creeks. The majority of creeks on the north-east side of the dam were not sampled for
this reason.
4.2 Time Constraints
This study was conducted over a relatively short period of three months, and did not
account for seasonal differences in macroinvertebrate diversity.
4.3 Taxonomic discrimination and ecological requirements of macroinvertebrates
Many freshwater taxa are currently undescribed, so it was only feasible to carry out
identification to the family level. Although all organisms present would optimally be
identified to the species level, measurement of species richness tends to be inexact
because of the lack of species-level identification keys for the immature stages (the
stages most commonly encountered in freshwater studies) of many groups of aquatic
insects (Rosenberg and Resh 1996). In Australia, there is limited knowledge on the
taxonomy, life histories and ecological requirements of freshwater
macroinvertebrates. Therefore, we cannot assess the specific reasons for the
distribution of the macroinvertebrates in the Manly Dam catchment.
4.4 Effectiveness of macroinvertebrates as biomonitors
Some characteristics of aquatic insects can hinder their effective use in biomonitoring
activities and require special consideration. Firstly, they do not respond directly to all
types of impacts e.g., herbicides (Hawkes 1979). Secondly, their distribution and
abundance can be affected by factors other than water quality (e.g., current velocity,
substrate type). Thirdly, seasonal variations in abundance and distribution are a
22Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
normal feature of many ecosystems, so results need careful interpretation (Abel,
1989). Fourthly, dispersal abilities may carry aquatic insects into and out of areas in
which they normally do not occur. In addition, some groups of aquatic insects lack
identification keys. Finally, quantitative sampling of macroinvertebrates is difficult
due to the physical characteristics of aquatic habitats and the complex horizontal and
vertical distribution patterns of some species (Abel, 1989).
4.5 Sampling techniques
All commonly used sampling techniques are very superficial, in that only the top few
centimetres of the substratum are sampled (Abel, 1989). Some animals burrow deep
within the substratum and a proportion of these are recovered by commonly used
sampling techniques such as kick sampling. In addition, some studies indicate that the
kick-sampling method can prove inadequate for highly mobile taxa that can flee from
the sampling point (Marchant & Hehir, 1999).
4.6 Numerical analysis
Both Sorensen and Jaccard analyses are purely qualitative techniques, and it must be
noted the choice of coefficient can significantly affect the outcome of the analysis. In
this case, the two coefficients used yielded similar results.
However, it is generally recommended that several coefficients be used and the results
compared before any definite conclusion is reached (Abel, 1989). According to Abel
(1989), a further level of sophistication is to estimate the degree of probability with
which sites are similar or different. This is necessary because most samples do not
include all the species present in the habitat.
23Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
5.0 Conclusion
The Manly Dam catchment supports a diverse community of freshwater
macroinvertebrates. The diversity varies considerably between the 12 sites, most
likely as a result of different habitat and food availabilities. A total of 39 families
from 13 orders was collected during the course of this study. The majority of animals
collected were insect larvae and nymphs, but also included crustaceans, molluscs and
oligochaetes.
It is difficult to assess the impacts of the various land uses around the catchment on
macroinvertebrate diversity. It was not possible to sample creeks which represented
the various land uses (residential, light industrial, recently developed) due to the
limited number of suitable sample sites, so we cannot determine if these of land uses
exerted any influence on macroinvertebrate diversity. Interestingly, the sample site at
the base of the golf course displayed the second-highest diversity of the sites sampled,
further indicating that the management practices of the golf course have improved and
do not appear to significantly affect the macroinvertebrate diversity, at least at this
site.
The macroinvertebrate fauna indicates the water quality is fair to good, based on the
Streamwatch results. The presence of very sensitive and sensitive macroinvertebrates
at the majority of sites is particularly encouraging.
This study has provides a baseline qualitative assessment of the macroinvertebrates
present in the Manly Dam catchment. There is considerable potential to utilise the
principles of biological monitoring to assess water quality in the Manly Dam
catchment, and this study can be used as to establish any changes in
macroinvertebrate diversity within the catchment over time.
6.0 Recommendations and Suggestions
The continuation of baseline monitoring in the Manly Dam catchment is
recommended, in order to understand the long-term changes in the ecological
communities. Furthermore, the sources of pollution, as well as their effects to the
water quality were not encountered in this study. Therefore ongoing monitoring of
water quality in the catchment, particularly in relation to known sources of pollution,
is needed to provide a useful resource for future studies in the catchment.
Boey (1997) recommends that a water quality sampling program for the Manly Dam
catchment be designed to meet requirements of water quality guidelines. Along with
monitoring of physical-chemical parameters, Boey (1997) suggests that biomonitoring
can complement such a program. Boey (1997) recommends that twelve sites within
the dam itself as well as along Curl Curl Creek be sampled twice annually. We
suggest a similar program as Boey, but more extensive sampling of the streams and
creeks around the catchment may also be of interest.
24Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
In addition, this study allows evaluation of any future management plans that are
undertaken within the Manly Dam catchment, using the aquatic macroinvertebrate
data to monitor changes over time. For example, an increase in macroinvertebrate
diversity may be an indication of improvements in water quality within the catchment.
Acknowledgments
The authors would like to thank Peter Jones and Dominic Cheng for their support and
assistance with this project. Special thanks to Dr. Richard Lim for supervising our
project and assisting in macroinvertebrate identification. Thanks also Sue Fenech for
assisting with the photomicroscopy of our reference collection and to Gemma
Armstrong for her assistance in the laboratory. Thanks to the members of the public
who attended the Manly Dam field day and students public seminar.
References
Abel, P.D. (1989). Water Pollution Biology. Ellis Horwood Ltd, England.
ANZECC (1992). National water quality management strategy, Australian water
quality guidelines for fresh and marine waters. Australian and New Zealand
Conservation Council, Canberra.
Bennison, G.L., Hillman, T.J., Suter, P.J. (1989). Macroinvertebrates of the River
Murray: Survey and Monitoring 1980-1985. Murray-Darling Basin Commission,
Victoria.
Boey, A. (1997). Manly Dam Catchment water quality studies: report for the
preparation of a plan of management for Manly Warringah War Memorial Park.
Department of Land and Water Conservation, NSW.
Crewe, R., Marrier d’Unienville, S., & Corby, E. (2000). Pollutant Sources in the
Manly Dam catchment area. In: UTS Freshwater Ecology Report of 2000, Dept
Environmental Sciences, University of Technology, Sydney.
Cairns, J., Jr., and J. R. Pratt. 1993. A history of biological monitoring using benthic
macroinvertebrates, pp. 10-27. In: Rosenberg, D.M. & Resh, V.H. (eds). Freshwater
biomonitoring and benthic macroinvertebrates. Chapman and Hall, New York.
Cummins, K.W. (1992). Invertebrates, pp234-249 In: Calow, P. & Petts, G.E (eds).
The Rivers Handbook: Hydrological and Ecological Principles Volume 1. Blackwell
Science Ltd, Oxford.
Hawkes, H. A. 1979. Invertebrates as indicators of river water quality, pp. 2-1 – 2-45.
In: A. James and L. Evison (eds). Biological indicators of water quality. John Wiley
and Sons, Chichester, England.
Hellawell, J. M. 1986. Biological indicators of freshwater pollution and
environmental management. Elsevier, London.
25Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Hughes, R. M., D. P. Larsen and J. Omernik. 1986. Regional reference sites: a method
for assessing stream potentials. Environmental Management, 10: 629-635.
Lenat, D.R., & Barbour, M.T. (1990). Using benthic macroinvertebrate community
structure for rapid cost effective water quality monitoring pp187-205. In: Loeb, S.L.
& Spacie, A (eds). Biological monitoring of Aquatic Systems. Lewis Publishers USA.
Marchant, R. & Hehir G. (1999). A method for quantifying hand-net samples of
stream invertebrates. Marine and Freshwater Research 50: 179-182.
Rosenberg, D.M., and V.H. Resh. 1996.Use of aquatic insects in biomonitoring, pp87-
97. In: Merritt, R.W., and K.W. Cummins (eds.). An Introduction to the Aquatic
Insects of North America. 3rd ed. Kendall-Hunt. United States of America.
Scullion, J., Parish, C.A., Morgan, N., & Edwards, R.W. (1982). Comparison of
benthic macroinvertebrate fauna and substratum composition in riffles and pools in
the impounded River Elan and the unregulated River Wye, mid-Wales. (1982).
Freshwater Biology 12: 579-595.
Streamwatch Online Manual. Accessed 25/10/01.
http://140.211.62.101/streamwatch/swm12a.html
Williams, D.D., and B.W. Feltmate. 1992. Aquatic Insects. CAB International.
26Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Appendix 1: Site Distribution of Macroinvertebrates in the Manly Dam
catchment
Order Family Site
1 2 3 4 5 6 7 8a 8b 9 10a 10b
Blattodea Dictyoptera +
Coeloptera Curculionidae +
Dytiscidae + + + + + +
Elmidae +
Helminthidae + +
Hydrophilidae + +
Limnichidae +
Psephenidae + + + + + + +
Diptera Chironomidae + + + + + + + + + + + +
Culicidae + +
Syrphidae
Tabanidae +
Tipulidae + +
Unknown +
Ephemeroptera Baetidae +
Caenidae +
Leptophlebiidae + + + + + + +
Hemiptera Coryxidae + + +
Notonectidae + + +
Hydracarina Morphospecies 1 +
Morphospecies 2 +
Morphospecies 3 +
Morphospecies 4 +
Morphospecies 5 +
Megaloptera Corydalidae + + +
Odonata Aeshnidae +
Corduliidae + +
Gomphidae +
Hemicorduliidae +
Megapodagrionidae + + +
Trichoptera Economidae + + + + + + +
Hydroptilidae + +
Leptoceridae +
Other
specimens
(order/class) Family/Phyla
Decapoda Atyidae + + + +
Gastropoda Lymnaeidae +
Physidae +
Oligochaetae + + + + + + + +
Turbellaria Tricladida +
27Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Appendix 2: Streamwatch Water Quality Analysis methods
Spring Water Bug Survey
Results Sheet
Stream Pollution Index & Stream Quality Rating
Calculation Table
The Water Bug Survey Stream Pollution Index has changed from
previous surveys. Please take time to read through the instructions
carefully.
Please complete the form using the data (no. of bugs found) from
the EDGE HABITAT. See New Sampling Procedures and Stream
Quality Rating Calculator.
Group Name: ............................................................................................... Group Size:
......................
Survey Site: ............................................................................................... Date Sampled:
.................
WEIGHT
TABLE
No. of
Step 1: Enter the number (i.e how many?) of each bug found in Column 2 Each Weight
Step 2: Refer to the Weight table for the correct Weight Factor for the number of bugs found Bug Factor
Step 3: Enter the correct Weight Factor for each bug in Column 3. Found (Colum
Step 4: Multiply the Bug Value (Column 1) by the Weight Factor (Column 3) and enter the answer in Column 4. (Colum n 3)
Step 5: Add up Column 3 (Weight Factors). n 2)
Step 6: Add up Column 4 (Bug Value x Weight Factor). 1-2 1
3-5 2
6-10 3
11-20 4
>20 5
Column 1 Column 2 Column 3 Column 4
Bug Value x
Number Weight
WATER BUG NAME Bug Value Weight
Found Factor
Factor
Very Sensitive Water Bugs
Stonefly Nymph 8
Freshwater Yabbie/Crayfish 7
Mayfly Nymph 7
Sensitive Water Bugs
Freshwater Mussel 6
Caddisfly Larvae 6
Damselfly Nymph 6
Dragonfly Nymph 6
Freshwater Shrimp 6
Watermite 5
Freshwater Sandhopper 5
Freshwater Slater 5
Tolerant Water Bugs
28Fong, M. & Nou, T. (2001). The diversity of benthic macroinvertebrates within the creeks of the
Manly Dam catchment. In: Freshwater Ecology Report of 2001, Department of Environmental
Sciences, University of Technology, Sydney.
Nematodes 4
Hydra 4
Beetle Larvae 4
True Bugs
(Backswimmer, Water Scorpion, Water
4
Boatman, Lesser Water Strider, Water
Strider/Treader)
Beetles (Dytiscid Beetles, Whirligig
3
Beetles)
Leeches 3
Snails (freshwater) 3
Flatworm 3
Very Tolerant Water Bugs
Mosquito Larvae 2
Midge Larvae 2
Fly Larvae 2
Aquatic Earthworm 1
Blood Worm 1
Totals
Step 7: Divide Total Column 4 by Total Column 3
To Calculate your Stream Pollution Index
Total Column 4
=
Total Column 3 Stream Pollution Index
Stream Pollution Index Stream Quality Rating
=
Less than 3 = Poor
3-4 = Fair
4-6 = Good
More than 6 = Excellent
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