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6 Conclusions Molecular Diversity and Dynamics of Toxigenic Blue-green Algae in Irish Lakes The enactment of environmental policies has made the identification and mediation of the factors that degrade surface waters essential. Evidence indicates that the incidence, duration and intensity of harmful algal blooms are increasing because of largely humanassisted alterations of the quality of aquatic environments. Blooms of noxious cyanobacteria occur worldwide and the risks they pose toward human and animal health have been demonstrated clearly. While significant efforts have been made to define the toxicological properties of cyanotoxins, additional efforts from researchers and environmental agencies to determine their toxicity potential and monitor and map their occurrences are required. Cyanobacteria form a very diverse group of microorganisms whose population dynamics are governed by the interplay of multiple ecological variables. The idea of a single-factor explanation elucidating the determinism of cyanobacteria blooms is not realistic. Instead, the development of adapted measures for particular species in specific aquatic ecosystems is more appropriate for preventing and mitigating noxious effects. Successful watermanagement strategies pertaining to occurrences of toxic cyanobacteria blooms will necessitate accurate identification of cyanobacteria species, together with a sound understanding of the environmental processes that govern their dynamics at the watershed level. In this context, regionalisation frameworks can enable the identification of groups of water bodies in spatially contiguous hydrological zones at risk of ecological status degradation. In complement, molecular methods constitute promising approaches for monitoring populations of both toxic and non-toxic cyanobacterial genotypes, and for elucidating the factors that drive their dynamics within phytoplankton assemblages. In Ireland, the management of anthropogenic pressures on water quality and biodiversity assessments in aquatic environments are of strategic relevance. Mortalities of wild and domestic animals have been associated with blooms of toxic cyanobacteria in Irish lakes. Ensuring that recreational and drinking waters are 62 free of toxins and pathogens is one of the most important challenges for regulatory authorities in the future. Due to the risks of human exposure to water contaminated with toxic cyanobacteria, it is necessary that the population dynamics of these organisms be investigated in Irish lakes for the future development of monitoring strategies and management tools, such as predictive models. This study investigated the summer variations in the molecular diversity of lacustrian cyanobacteria at a regional level in the west of Ireland. DGGE fingerprinting of 16S rDNA enabled an assessment of the variation in planktonic cyanobacteria community composition among lakes interspersed within various river catchments, highlighting seasonality and the range of land cover typology in the study area. As anticipated, there was wide variation in the structure of the communities sampled. PCR-based analysis of a microcystin-coding gene and analysis of natural extracts by PP2A and analytical chemistry also confirmed the presence of potentially toxic species in multiple lakes within the study area. It is important to consider both spatial and temporal scales to understand the dynamics of primary productivity in relation to biophysical interactions and nutrient loadings in aquatic systems. This study suggested that the application of regionalisation schemes for watershed sampling could be complemented effectively by spreading out the sampling effort in time, returning a dynamic environmental assessment. The assessment of regional diversity patterns in cyanobacterial assemblages constitutes an innovative approach to microbial ecology and shows great potential for incorporation into a battery of methods for the management of aquatic resources. In the future, coupling molecular analysis to routine microbial monitoring programmes could allow the rapid generation of cyanobacterial assemblage fingerprints. The subsequent interpretation of their diversity and dynamics, at varying scales of space and time, would contribute then to the evaluation of the efficiency of the environmental policies introduced to improve lake trophic state and water quality in general.
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STRIVE Report Series No.88 Molecula
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EPA STRIVE Programme 2007-2013 Mole
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Details of Project Partners Nicolas
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3.4 Phytoplankton Community Structu
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1 Introduction Occurrences of harmf
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differentiated cells. The bacteriol
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not cyanobacteria are the only sour
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clustering methods can provide an e
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ody of evidence indicating that mic
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