The Effects of Road Transport on Freshwater and Marine Ecosystems

64
considered that taxa richness was relatively high in the New Zealand urban streams they studied.
Suren (2000) notes that as urban streams are typically highly modified and water quality is low the
overall ecosystem in urban streams is degraded and this is then reflected in the nature <strong>of</strong> the macroinvertebrate
community present (especially when compared with non-urban streams). <strong>The</strong>re have a
number <strong>of</strong> studies in New Zealand that have examined the biological resources <strong>of</strong> urban streams.
<strong>The</strong>se studies include Kingett Mitchell (2000) who examined stream environments in Waitakere City;
Kingett Mitchell (2001), urban streams in North Shore City catchments; Suren (2001), urban streams
in Auckland City; Wilding (1996, 1999) urban streams in Auckland; Kingett Mitchell (in prep),
Wellington steams and Macaskill et al. (2003), Rotorua City. Table 6.2 summarises the results <strong>of</strong> the
study undertaken in Waitakere City (Kingett Mitchell 2000), which illustrates some <strong>of</strong> the trends in
macroinvertebrate metrics.
Table 6.2 - Invertebrate indices scores for streams in Waitakere City grouped by land use.
(taken from Kingett Mitchell 2000).
Land use Taxa
No.
EPT
Taxa No.
EPT
Ratio
QMCI QUCI Margalefs % Dominant
taxon
Native bush 19 ± 2 8.3 ± 3.2 0.5 ± 0.2 5.6 ± 1.1 0.9 ± 0.2 3.5 ± 0.3 34 ± 6
Urban/bush 11 ± 4 3.4 ± 1.3 0.0 ± 0.0 5.0 ± 0.3 1.0 ± 0.4 1.8 ± 0.5 71 ± 9
Rural 17 ± 1 3.6 ± 1.2 0.1 ± 0.1 3.6 ± 0.3 0.4 ± 0.2 2.6 ± 0.2 48 ± 7
Urban/rural 15 ± 3 2.0 ± 1.0 0.0 ± 0.0 2.9 ± 0.2 0.4 ± 0.4 2.3 ± 0.0 52 ± 23
Urban 9 ± 1 0.5 ± 0.2 0.0 ± 0.0 3.2 ± 0.2 0.0 ± 0.0 1.4 ± 0.1 66 ± 5
Note: Values are presented as mean ± 1 standard deviation.
General Tools
Macroinvertebrates are the most commonly used bio-monitoring tool when freshwater bio-monitoring
is undertaken (Rosenberg & Resh 1993). In general, benthic invertebrate bio-monitoring focuses on
community level characteristics such as taxonomic diversity and the presence/absence <strong>of</strong> sensitive
indicator species. More recently bio-monitoring investigations have assessed the effect <strong>of</strong> specific
environmental stressors on biochemical, genetic, morphological and physiological changes.
Macroinvertebrates assimilate and reflect water quality and habitat conditions over time and are
therefore ideal indicators <strong>of</strong> environmental stress. Advantages <strong>of</strong> using benthic macroinvertebrates in
biomonitoring programmes include:
1. Commonly occurring.
2. Community diversity reflects a wide range <strong>of</strong> environmental stressors.
3. Relatively sedentary and therefore reflect localised conditions.
4. Bio-accumulate toxic substances.
5. Detectable changes in community structure are obvious to trained biologists.
6. Easily collected and identified.
7. Integrate multiple stressors and therefore reflect overall stream health.
Benthic macroinvertebrates are widely used by freshwater managers in New Zealand to assess and
monitor water quality and in-stream health. In New Zealand, benthic invertebrate bio-monitoring has
focused on community level data. A range <strong>of</strong> biological indices has been used to simplify complex
species lists into single numbers that are easily understood by non-biologists. <strong>The</strong> inset box provides
a summary <strong>of</strong> the range <strong>of</strong> indices and metrics available with which to assess community well-being.
Tools with specific relevance to assessing road transport effects
Tools, which are specific to assessing road run<strong>of</strong>f effects on macro-invertebrate communities in
stream environments, have not been identified in this review. <strong>The</strong> strength <strong>of</strong> invertebrate bio-
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