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A Diatom Prediction Model and Classification for Urban Streams from Perth, Western Australia.

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A Diatom Prediction Model and Classification for Urban Streams from Perth, Western Australia.

Jacob John (Unbekannter Einband, Englisch)

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Abstract: The metropolitan city of Perth has its beginning with the establishment of the Swan River Colony in 1829, around the Swan-Canning River estuary. Within the last 183 years the city has expanded with almost 1.4 million people inhabiting the metropolitan city impacting heavily on the ecology of the River system. Several natural streams discharging into the system have been drastically modified by intense urbanisation. The River system and its tributaries, streams and drains have been the recipients of nutrients, effluents, and waste water from the urban and rural catchments resulting in severe symptoms of eutrophication over the past several decades. While the rural catchments have been implicated in the eutrophication and pollution of the estuary, the contribution of urban catchments to the degradation of the system is relatively less known. Through urban catchment groups, and the Integrated Catchment Management Policy, the importance of urban streams and drains is just beginning to be recognised. The current project was aimed at developing a predictive model for biomonitoring the urban streams using diatoms as tools. The investigation lasting from 1996 to 1999 focussed on classification of the urban streams using water quality parameters and 'stream conditions' and subsequent development of a predictive model using diatoms as biomonitors. Close to 180 sites were sampled in summer 1996, spring-summer 1997 and autumn-winter 1997 recording as many as 30 environmental variables. These sites represented most of the streams and drains (including 'concrete') in the urban and semi-rural areas of Perth. The sampling sites were established after analyzing the historical data on water quality and catchment conditions, as well as from preliminary observations. A large number of 'reference sites' or 'relatively pristine sites' were required for the model. The semi-rural sites provided the best examples of reference sites, as they were least impacted by urbanisation. Diatom samples from both reference and impacted sites were collected using an artificial sampling device the JJ Periphytometer. All sites were classified on the basis of seven environmental variables, with the highest correlation coefficient with the sites. Agglomerative hierarchical fusion method with flexible unweighted pair group mean averages (UPGMA) within the multivariate pattern analysis program PATN was used. However, currently, PRIMER SOFTWARE (Plymouth Routine In Mutivariate Ecological Research) is considered to be a more efficient multivariate program. The dendrogram with the sites clustered according to their similarity was further analysed and the status of some of the sites revised, recognising a third group 'the Intermediates'. Out of more than 208 species of diatoms recorded from the sampling sites, 57 species selected on the basis of their relative frequencies, were used for the classification of the sites to show the similarity in the distribution pattern of diatoms. Diatom assemblages with similar ecological preferences were clustered together. Discriminant function analysis showed that there was a high degree of concordance between the two classifications. Multi-dimensional Scaling (MDS) was employed for ordination of sites based on diatom assemblages. Environmental variables were related to the ordination with principal axis correlation. Stream conditions such as water table depth and percentage of native vegetation had significant correlation with pristine sites, whereas, alkalinity, electrical conductivity, ground water salinity, catchment land use, riparian damage and colour had significant correlation coefficients with the impacted sites. The distribution patterns of diatoms were separated into three distinct groups: Reference, Monitoring and Intermediate - within the intermediate group, the brackish sites were further separated. Several indicator species were recognised on the basis of the correlation of the species to the sites. A two-way table with the distribution pattern of diatoms constrained on the site groups was generated. This table can be used to assess the health of any site chosen. The diatom assemblages of the test site can be added to the horizontal rows with their relative frequency. The test site then may be clustered with Impacted or Reference or Intermediate groups. In this way, an assessment of its health may be made. Based upon the indicator species for Reference and Impacted sites, a diatom index with predictive power has been designed. The health of any site can be assessed by providing the information on the relative frequency of diatom species present in the site. The predictive model was derived from the data collected from spring-summer 1997 but was successfully tested on winter samples 1997. The relatively high universality of diatom species distribution makes them ideal biomonitors at the regional and national level. The distribution pattern of diatoms in the urban streams and drains in the metropolitan city of Perth was highly correlated with the environmental factors associated with the ecological integrity and stream conditions. The predictive model developed in this project has the potential to be adapted for use in other urban areas of Australia Weniger zeigen

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Produktinformationen

Technische Daten

Erscheinungsdatum

25.01.2013

Sprache

Englisch

EAN

9783874294300

Herausgeber

Koeltz Botanical Books

Sonderedition

Nein

Autor

Jacob John

Seitenanzahl

166

Einbandart

Unbekannter Einband

Einbandart Details

Pappband

Schlagwörter

Perth, Urban Streams, Diatomeen, Prediction Model, Diatom Prediction Model, Diatoms, Kieselalgen

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