Environmental Engineering Reference
In-Depth Information
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Figure 8.4.
The preliminary diatom record from Martins Bend near Berri in the
Riverland of South Australia. The acidophilic diatom taxa Pinnularia spp. have come to
dominate the record due to what appears to be an unprecedented acidification event
(data from Dr Jennie Fluin). The Rhopalodia, Fallacia and Gyrosigma taxa attest to a shallow,
saline baseline in this case with the Aulacoseira rise indicative of river regulation
bringing freshwater to the site on a more regular basis.
sediments and elements contained within. The development of catchments for
the agriculture industry was often coincident with other developments that
brought on additional direct and diffuse forms of pollution. Furthermore, the
interrelationships between salinisation, erosion and nutrient release (Prosser
et al.
2001
) mean that one driver of change can induce symptoms more usually
attributed to others. These factors make it difficult to attribute changes in
biological and chemical indicators to particular drivers of change, and so to
particular changes in land use (Gell et al.
2007a
). The record of wetland change
derived from fossil diatoms can quantitatively indicate changes in a particular
water quality variable over time through the use of transfer functions. Where
there are multiple drivers and stressors acting on the system coincidentally the
quantitative reconstructions are confounded. In these grossly disturbed sites,
several widely tolerant taxa come to dominate. Diatom species such as Cyclotella
meneghiniana or Staurosirella pinnata, for example, are advantaged by increased
water turbidity, salinity and nutrient concentrations. Actinocyclus normanii, that
appears to have increased recently in abundance in both the Murray and
Mississippi Rivers, is considered to be reflective of recent increased salinity
