Browsing Marine Environment & Food Safety Services by Subject "Variability"
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Biomarkers: are realism and control mutually exclusive in integrated pollution assessment?The conventional view of pollution monitoring is that any choice is a trade-off between realism and precision, as the control over confounding variables decreases with the increasing degree of organization of the test system. Dublin Bay is subject to considerable anthropogenic pressures and there have been many attempts to quantify the status of the system at organizational levels from DNA strand breaks (Comet) to the system itself (Ecological Network analysis, ENA). Using Dublin Bay as an example, the data show there was considerable variability at all levels of organization. At intracellular level, Lysosome Membrane Stability (LMS, assessed by Neutral Red Retention, NRR) varied almost 4-fold with season and individual condition, while the community level AZTI Marine biotic Index (AMBI) had a similar range within a single, supposedly homogeneous, site. Overall, there was no evidence that biomarkers of the lower levels of organisation reduced the variability of the measure, despite the extra control over influencing variables, nor was there any evidence that variability was additive at higher levels of organisation. This poses problems for management, especially given the fixed limits of Ecological Quality Standards (EQSs). Clearly while the integrated approach to pollution monitoring does offer the potential to link effects across the organizational range, it should also be possible to improve their capability by widening the database for reference values, particularly at the higher level of organization, and by process models, including the confounding variables found in the field, for those at lower level.
Use of LC-MS testing to identify lipophilic toxins, to establish local trends and interspecies differences and to test the comparability of LC-MS testing with the mouse bioassay: an example from the Irish biotoxin monitoring programme 2001During 2001, the Marine Institute has extended its range of chemical tests to include the analysis of DSP toxins by Liquid Chromatography coupled to Mass Spectrometry (LC-MS). Thus the range of compounds determined extends from domoic acid over DSP compounds (okadaic acid and DTXs) to azaspiracids (AZAs). These tests complement the mouse bioassay, which is the current reference method for lipophilic toxins within the European Community. The development and performance characteristics of the LC-MS method are discussed. Isomer patterns and interspecies differences are discussed as well as local trends in time and variability at one production site at a given time. Comparison of the LC-MS results with the results from the mouse bioassay showed good agreement (93%), and a small but significant number of discrepancies (7%). Overall, the chemical testing has proven to be an invaluable tool in the assessment of shellfish toxicity in Ireland. Lacks of standards and reference materials are discussed as well as the need for further research into the equivalence of methods.