Gladstone Fish Health Investigation 2011 - 2012 - Western Basin ...

Contaminants in Tissue of o Fish and Crabs Collectedin the Gladstone Area3.4. Statistical AnalysisVery few organics were detectedd in the mudd crab hepatopancreas(the only mud crab tissueanalysed) and so these results were not analysed statistically. Statistical analysis was undertakenusing a general linearmodel (GLM) in orderr to investigate whether there weree statisticallysignificant associations between observed signs of fishhealth (seee DAFF 2012 for methodology)and measured metal concentrations in the organisms sampled. In addition, analysis of themeasured concentrations of metals and metalloids at eference sites and Gladstone harbour sitesin each tissue group sampled were undertaken. Appendix A outlines the detailed statisticalmethods and results from the statistical analysis of metal concentrations measured in themud crabhepatopancreas and Appendix B outlines the methods and resultss for the assessment off themeasured metals andmetalloids in barramundi gill andliver tissuee samples and grinner muscletissue. A sensitivity analysis was undertakenn where samples had measured m concentrations at orjust above the limit of reporting. This analysis is presented in Appendix C.Data from historical analyses of measured metal concentrations inn mud crab hepatopancreastissue expressed as dry weights were collected from the literature (Mortimer 2000; Negri et al2009) and combined with data from the current survey. A principall component analysis (PCA)(wasundertakenn on the combined dataa in order too assess whether the current c tissue samples fromGladstone had unusually high contaminantss concentrations compared to historical data from fGladstone Harbour orother catchments along the east coast of Queensland.Principal componentsanalysis (PCA) (Stevens 1986) isa multivariate statistical method. . It constructs linear combinationsof all the variates thatt maximize the t variationn containedwithin them, thereby summarising theoverall patterns and displaying most of the original variability in a smaller s number of dimensions(typically two, visualised as a scatterplot). No historical concentration data could be located forbarramundi gill and liver or grinner flesh andd so analysis of these samples s was limited tocomparison between reference and Gladstone Harbourr sites, undertaken using the GLM. The levelof statistical inferencee for all statistical analyses was taken to be 0.05.3.5.Toxicological Effects AssessmentTissue residue data from the current study were compared to dataa retrieved from theEnvironmental Residue and Effects Database (US Army Corp Engineers & USEPA 2011). Thisdatabase is sourced from the literature. It contains dataa from studies where biological effects andtissue contaminant concentrations were simultaneouslymeasuredd in the same organism. Datarelating to mortality/survival, growth and reproduction were used for the comparison.Page 7