6 results for Lear, Gavin, Conference poster, 2008

  • Effects of Storm water metal contaminats on microbial communities in stream biofilm revealed by Automated Ribosomal Intergenic Spacer Analysis (ARISA)

    Ancion, Pierre; Lear, Gavin; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    Stormwater metal contaminants are known to be a threat to our freshwater environments but little is known about their effects on stream micro-organisms. This project investigates accumulation and release of the most common stormwater metal contaminants (zinc, copper and lead) in stream biofilms and their effects on bacterial populations.

    View record details
  • Use of whole-community bacterial indicators to monitor ecological health, function and variability within freshwater stream biofilms.

    Lear, Gavin; Smith, Joanna; Roberts, Kelly; Boothroyd, Ian; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    This study describes the extent of variability in biofilm bacterial community structure across a broad range of spatial and temporal scales and assesses whether this may be used as an indicator of stream ecological health and function. A community DNA fingerprinting technique (Automated Ribosomal Intergenic Spacer Analysis - ARISA) was used to examine the structure of bacterial communities within freshwater stream biofilms. When compared with macrobenthic invertebrate community assemblages using multi-dimensional scaling techniques, similar broad-scale trends in population structure were revealed between organisms at these different trophic levels. For both communities, spatial variability in community structure was greater between streams than within each site, or compared to temporal variability measured over 1 year. Distance-based redundancy analysis of both bacterial ARISA and macroinvertebrate data estimated that the largest cause of variation in community structure was due to differences in catchment land-use, rather than any single water quality parameter (e.g. ph or ammoniacal nitrogen). Multidimensional scaling of ARISA data also revealed significant differences in community structure between urban, and less impacted stream sites, providing evidence that whole-bacterial communities could be used as an indicator of freshwater ecological health, analogous to the way that macroinvertebrate communities have been used for many years. In conclusion, we propose the analysis of whole bacterial communities as a cost-effective, high throughput alternative indicator of freshwater ecological health.

    View record details
  • Human Activities Modify Bacterial Diversity in Stream Benthic Biofilm Communities

    Lewis, Gillian; Roberts, Kelly; Turner, Susan; Lear, Gavin (2008-06-01)

    Conference poster
    The University of Auckland Library

    This study tests the hypothesis that human impact is an important driver of stream biofilm bacterial population diversity. The seasonal bacterial composition of biofilm in 4 streams with different levels of human impact was determined over 2 years. Bacterial diversity derived from 16S rDNA clone libraries, shows both between stream differences and seasonal transitions in bacterial occurrence and population dominance at a class and genus level. Diversity analysis calculated on pooled seasonal data (class level identification) shows that while composition of the populations are different there is a similar level of both bacterial richness and bacterial diversity in each stream. Trends in bacterial occurrence suggest that the most degraded stream were dominated by cyanobacteria, the mid range impact streams by aeromonads and gamma proteobacteria, while the unimpacted stream showed both high diversity and no dominance by any particular class.

    View record details
  • What drives bacterial community structure in stream biofilms?

    Roberts, Kelly; Lear, Gavin; Turner, Susan; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    BACKGROUND The microorganisms within biofilms are the key basal trophic level within most freshwater systems. However, microbial structure, function and succession in natural stream systems remain poorly understood. This research characterises the biofilm community structure of stream biofilms experiencing different anthropogenic impacts and how they change over time. Our aim is describe the changes in bacterial biofilm communities over time and to investigate what drives these changes.

    View record details
  • Stream Restoration: Getting the microbial ecology right.

    Lewis, Gillian; Lear, Gavin; Turner, Susan; Boothroyd, Ian; Stott, Rebecca; Roberts, Kelly; Ancion, Pierre; Dopheide, Andrew; Washington, Vidya; Knight, Duane; Smith, Joanna (2008-08-17)

    Conference poster
    The University of Auckland Library

    A comprehensive program to re-establish the structure and function of an ecosystem, including its natural diversity and aquatic habitats.

    View record details
  • Ciliate Diversity in Stream Biofilms revealed by group-specific PCR primers.

    Dopheide, Andrew; Lear, Gavin; Stott, R; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    The ciliates are a diverse protozoan phylum, thought to be of considerable ecological importance in stream ecosystems, including organisms which are abundant and important consumers of bacteria, algae and other protozoa. Understanding of ciliate diversity and ecology is limited, however, particularly in benthic habitats such as stream biofilms. In this study, phylum-specific PCR primers were used in combination with cloning, sequencing and terminal restriction fragment length polymorphism (T-RFLP) analysis to investigate ciliate communities in stream biofilms.

    View record details