The Effects of Road Transport on Freshwater and Marine Ecosystems

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A number <strong>of</strong> studies carried out in the Auckland area have shown differences in the quality <strong>of</strong> sediment
benthic invertebrate communities in estuaries with catchments <strong>of</strong> varying intensities <strong>of</strong> urban
development. Recent work undertaken by ARC has indicated that there are good relationships between
macroinvertebrate benthic health in s<strong>of</strong>t muddy sediments and the quality <strong>of</strong> those sediments (as
reflected in the concentrations <strong>of</strong> Cu, Pb and Zn). However, the observed biological response seen in the
field does not reflect urban stormwater contributions from those catchments. At this point in time, the
available data indicates that the relationship between sediment quality (contaminants derived from urban
run<strong>of</strong>f) and biological effects is somewhat unclear.
<strong>The</strong> assessment <strong>of</strong> bioaccumulation in marine organisms provides a tool to assess the flux <strong>of</strong> road
transport associated contaminants. No contaminants have been identified that are unique to road
transport that would allow the specific effects <strong>of</strong> road transport on uptake <strong>of</strong> contaminants by marine
organisms to be isolated in urban areas. It is likely that road transport contributes in part to any biouptake
<strong>of</strong> contaminants by marine organisms adjacent to roads and urban areas. Two <strong>of</strong> the key trace
element contaminants Cu and Zn are not typically bioaccumulated by many marine organisms. Some
shellfish (e.g., oysters) will accumulate Zn. At this point in time there is no information that indicates that
road transport contributes to uptake <strong>of</strong> contaminants by marine organisms such that they are rendered
unsuitable for human consumption.
Kingett Mitchell Ltd
Resource & Environmental Consultants