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dc.contributor.authorSimpson, Julia Marieen_NZ
dc.date.accessioned2009-03-13T12:10:42Z
dc.date.available2009-07-29T15:33:27Z
dc.date.issued2009en_NZ
dc.identifier.citationSimpson, J. M. (2009). Effects of heavy metal contamination on burial rates of Austrovenus stutchburyi: Implications for sediment transport (Thesis, Master of Science (MSc)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/2766en
dc.identifier.urihttps://hdl.handle.net/10289/2766
dc.description.abstractUrbanisation in coastal catchments has significantly increased not only the input of terrestrial sediment to the marine environment but also the input of contaminants. In Tamaki Estuary, Auckland, heavy metals have accumulated in the upper estuarine muddy sediments and metal contamination has been detected on downstream intertidal sandflats. Sub-lethal levels of heavy metal contamination may affect the growth and behaviour of benthic organisms, which in turn may influence key ecosystem processes and productivity. The aim of this study was to examine whether the burial rate of an ecologically important bivalve species (Austrovenus stutchburyi) differed between a contaminated and a lesser-contaminated site and whether burial rates were affected by density. A secondary aim was to determine whether the burial of Austrovenus affected sediment transport and consequently if this was affected by density. This study demonstrated no consistent difference in burial time between source populations (sites). This was explained by a lack of measured difference in the condition index and heavy metal tissue loading of Austrovenus used throughout this study. The present range of contamination measured in Tamaki Estuary, Auckland, did not have negative biological consequences on the key ecosystem engineer, Austrovenus stutchburyi. Contamination levels in Tamaki Estuary may not be high enough to cause major physiological or behaviour changes to infaunal organisms, such as Austrovenus. Sediment erodability was not significantly correlated with any measured environmental and biotic factors. Austrovenus density was the only predictor variable that could be used to explain any variation in sediment erodability. There was no significant density effects observed between the amounts of sediment eroded for densities gt; 150 ind. m-2. There was a significant difference between sediment void of Austrovenus (0 ind. m-2; smooth, flat undisturbed sediment surface) and sediment containing Austrovenus (gt;150ind. m-2; physical structure on/in the sediment surface, increase in bed roughness). These results indicate that there is little or no effect of Austrovenus on the critical erosion threshold, suggesting that in the absence or presence of Austrovenus the current required to erode 10 g m-2 of sediment would remain somewhere between 28.5 and 30.5 cm s-1. This study found that there was considerable variation in the burial rate of individuals and the greatest variation was recorded in the lowest density treatments (150 ind. m-2), which corresponded to the same density that had the greatest variation in sediment erodability. Further investigations are needed to gain a better understanding into the important roles (the importance of the various feedbacks and limitations and interrelationships) that Austrovenus play in the soft-sediment ecosystem, as losses of this species are likely to have large-scale impacts on the wider soft-sediment communities and ecosystem functioning.en_NZ
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherThe University of Waikatoen_NZ
dc.rightsAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectAustrovenus stutchburyien_NZ
dc.subjectheavy metalsen_NZ
dc.subjectsedimenten_NZ
dc.subjectbioturbationen_NZ
dc.titleEffects of heavy metal contamination on burial rates of Austrovenus stutchburyi: Implications for sediment transporten_NZ
dc.typeThesisen_NZ
thesis.degree.disciplineScience and Engineeringen_NZ
thesis.degree.grantorUniversity of Waikatoen_NZ
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (MSc)en_NZ
uow.date.accession2009-03-13T12:10:42Zen_NZ
uow.date.available2009-07-29T15:33:27Zen_NZ
uow.identifier.adthttp://adt.waikato.ac.nz/public/adt-uow20090313.121042en_NZ
pubs.elements-id55730
pubs.place-of-publicationHamilton, New Zealanden_NZ


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