title: Effects of heavy metal contamination on burial rates of Austrovenus stutchburyi: Implications for sediment transport

authors: Simpson, Julia Marie

subjects: Austrovenus stutchburyi

abstract: Urbanisation 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.

text: Effects of heavy metal contamination on burial rates of Austrovenus stutchburyi: Implications for sediment transport Urbanisation 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.

year: 2009

title: Catnesses

authors: Legg, Catherine

subjects: philosophy

abstract: An introduction to cat metaphysics.

text: Catnesses An introduction to cat metaphysics.

year: 2008

title: Te Whatu Kakahu: Assessment in Kaupapa Maori Early Childhood Practice

authors: Rameka, Lesley Kay

subjects: Kaupapa Maori

abstract: Through the exploration of Kaupapa Māori assessment approaches, I examine the reclaiming and reframing of Māori ways of knowing and being within early childhood practice. Assessment is the vehicle for reclaiming and reframing while Kaupapa Māori theory is the fuel that ignites and drives the vehicle.

The effects of successive education policies remain today with Māori children, and their families continuing to disengage from education and consistently receiving disproportionately lower outcomes, opportunities and benefits. Reclaiming and reframing Māori ways of knowing and being within early childhood assessment thinking and practice is a means of addressing the cultural and educational disparities faced by Māori children within an education system that upholds western cultural and educational superiority, privilege and truths.  Key questions in this process of reclaiming and reframing are: Who has the power to define?  Whose truths are being reflected and how are these truths constructed? 

The metaphor of whatu kākahu or weaving of clothing has been used to frame this thesis. The process has involved weaving the Kaupapa Māori theory elements of conscientisation, resistance, transformative praxis and Māori ways of knowing and being, across and within historical, cultural and educational paradigms and understandings, to fashion assessment kākahu that afford comfort, warmth and flexibility in a contemporary early childhood context. This research case studies the progress of three Māori early childhood services and kōhanga reo towards the development of Kaupapa Māori early childhood assessment understandings and framings (kākahu), that reflect their particular ways of knowing and being, context and aspirations for children. This thesis has been about their assessment journeys. These journeys are a work in progress and that work continues.

A qualitative, Kaupapa Māori research methodology was used to gather, collate and analyse data in this research.  In accordance with Kaupapa Māori research aspirations and expectations, this research focuses on areas of importance and concern for Māori, and involved retrieving space for Māori voices to be heard. This research can be seen as a means of privileging Māori approaches, perspectives and ways of knowing and being in early childhood assessment practice.

Kaupapa Māori assessment is an important agenda for early childhood.   It builds upon Māori philosophical and epistemological understandings that express Māori ways of knowing and being. Kaupapa Māori assessment is able to contribute significantly to children’s learning and potential growth and is an important tool in constructing educational outcomes for Māori children. It is therefore an important agenda for early childhood.

text: Te Whatu Kakahu: Assessment in Kaupapa Maori Early Childhood Practice Through the exploration of Kaupapa Māori assessment approaches, I examine the reclaiming and reframing of Māori ways of knowing and being within early childhood practice. Assessment is the vehicle for reclaiming and reframing while Kaupapa Māori theory is the fuel that ignites and drives the vehicle.

The effects of successive education policies remain today with Māori children, and their families continuing to disengage from education and consistently receiving disproportionately lower outcomes, opportunities and benefits. Reclaiming and reframing Māori ways of knowing and being within early childhood assessment thinking and practice is a means of addressing the cultural and educational disparities faced by Māori children within an education system that upholds western cultural and educational superiority, privilege and truths.  Key questions in this process of reclaiming and reframing are: Who has the power to define?  Whose truths are being reflected and how are these truths constructed? 

The metaphor of whatu kākahu or weaving of clothing has been used to frame this thesis. The process has involved weaving the Kaupapa Māori theory elements of conscientisation, resistance, transformative praxis and Māori ways of knowing and being, across and within historical, cultural and educational paradigms and understandings, to fashion assessment kākahu that afford comfort, warmth and flexibility in a contemporary early childhood context. This research case studies the progress of three Māori early childhood services and kōhanga reo towards the development of Kaupapa Māori early childhood assessment understandings and framings (kākahu), that reflect their particular ways of knowing and being, context and aspirations for children. This thesis has been about their assessment journeys. These journeys are a work in progress and that work continues.

A qualitative, Kaupapa Māori research methodology was used to gather, collate and analyse data in this research.  In accordance with Kaupapa Māori research aspirations and expectations, this research focuses on areas of importance and concern for Māori, and involved retrieving space for Māori voices to be heard. This research can be seen as a means of privileging Māori approaches, perspectives and ways of knowing and being in early childhood assessment practice.

Kaupapa Māori assessment is an important agenda for early childhood.   It builds upon Māori philosophical and epistemological understandings that express Māori ways of knowing and being. Kaupapa Māori assessment is able to contribute significantly to children’s learning and potential growth and is an important tool in constructing educational outcomes for Māori children. It is therefore an important agenda for early childhood.

year: 2012