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: A review of the airport-low cost airline relationship

authors: Humphreys, Ian

subjects: airports

abstract: This paper seeks to review the airport-airline relationship in the light of the growth in the low cost sector, identifying important issues that airport management should consider when negotiating with low cost airlines. Airports have responded to the potential opportunities that have arisen from the growth of low cost airlines. The low cost model has implications for the airline-airport relationship, forcing airports to negotiate contracts which significantly reduce aeronautical revenues whilst seeking to address this short fall by commercial revenues via increased passenger numbers. Airports have sometimes found it difficult to turn increased passenger volume into additional revenue.

text: A review of the airport-low cost airline relationship This paper seeks to review the airport-airline relationship in the light of the growth in the low cost sector, identifying important issues that airport management should consider when negotiating with low cost airlines. Airports have responded to the potential opportunities that have arisen from the growth of low cost airlines. The low cost model has implications for the airline-airport relationship, forcing airports to negotiate contracts which significantly reduce aeronautical revenues whilst seeking to address this short fall by commercial revenues via increased passenger numbers. Airports have sometimes found it difficult to turn increased passenger volume into additional revenue.

year: 2006

title: The use of functionalised biochar to enhance phosphorus removal in woodchip bioreactors. The integration of mātauranga Māori to enhance the cultural aspects of woodchip bioreactors.

authors: Taoho, Brandon

subjects: Woodchip bioreactor

abstract: Nutrient pollution, resulting from excessive releases of nitrogen (N) and phosphorus (P) into waterways, poses a significant threat to aquatic ecosystems worldwide. Elevated nutrient levels can result in eutrophication, which can have detrimental effects on the health of waterbodies and their biota. Woodchip bioreactors are effective, edge-of-field technologies that can help mitigate nutrient pollution by lowering nutrient concentrations in agricultural drainage systems known to carry leached N and P into waterways. However, one limitation to their design is their ineffectiveness at removing P. The inclusion of functionalised biochar is one potential solution to enhance P removal in woodchip bioreactors. There is a growing need to mitigate nutrient pollution in New Zealand that does not depend on a western-centric perspective only. Integration of mātauranga Māori and western science into the design and operations of a woodchip bioreactor is one approach to incorporate both knowledge systems to the goal of mitigating nutrient pollution. In this dissertation, a column experiment was used to compare the P removal efficiencies of two treatments of functionalised biochar, and one treatment of woodchips when subjected to stream water spiked with P. Subsequently, a single phosphate extraction was done to determine the phosphate absorption capacities of each treatment. The results showed that the two functionalised biochar treatments had the highest efficacy in reducing P concentrations in the P-spiked stream water compared to the woodchip-only treatment. Both treatments also showed higher P absorption, evidenced from the Fe-P/Feox ratio, within the phosphate extraction experiment. A wānanga was organised at Matahuru Marae, Lake Waikare, to share mātauranga Māori on how to culturally enhance woodchip bioreactors from a Te Ao Māori perspective. Participants recommended that native woodchips be incorporated into woodchip bioreactors because of their inherent association to the land and people. Overall, the results implied that functionalised biochar is an effective solution to enhance P removal in woodchip bioreactors due to their biophysical properties to absorb and retain P. Secondly, incorporating native woodchips into woodchip bioreactors systems potentially offers a sustainable and culturally respected alternative to conventional wood chips, aligning with Māori values and tikanga

text: The use of functionalised biochar to enhance phosphorus removal in woodchip bioreactors. The integration of mātauranga Māori to enhance the cultural aspects of woodchip bioreactors. Nutrient pollution, resulting from excessive releases of nitrogen (N) and phosphorus (P) into waterways, poses a significant threat to aquatic ecosystems worldwide. Elevated nutrient levels can result in eutrophication, which can have detrimental effects on the health of waterbodies and their biota. Woodchip bioreactors are effective, edge-of-field technologies that can help mitigate nutrient pollution by lowering nutrient concentrations in agricultural drainage systems known to carry leached N and P into waterways. However, one limitation to their design is their ineffectiveness at removing P. The inclusion of functionalised biochar is one potential solution to enhance P removal in woodchip bioreactors. There is a growing need to mitigate nutrient pollution in New Zealand that does not depend on a western-centric perspective only. Integration of mātauranga Māori and western science into the design and operations of a woodchip bioreactor is one approach to incorporate both knowledge systems to the goal of mitigating nutrient pollution. In this dissertation, a column experiment was used to compare the P removal efficiencies of two treatments of functionalised biochar, and one treatment of woodchips when subjected to stream water spiked with P. Subsequently, a single phosphate extraction was done to determine the phosphate absorption capacities of each treatment. The results showed that the two functionalised biochar treatments had the highest efficacy in reducing P concentrations in the P-spiked stream water compared to the woodchip-only treatment. Both treatments also showed higher P absorption, evidenced from the Fe-P/Feox ratio, within the phosphate extraction experiment. A wānanga was organised at Matahuru Marae, Lake Waikare, to share mātauranga Māori on how to culturally enhance woodchip bioreactors from a Te Ao Māori perspective. Participants recommended that native woodchips be incorporated into woodchip bioreactors because of their inherent association to the land and people. Overall, the results implied that functionalised biochar is an effective solution to enhance P removal in woodchip bioreactors due to their biophysical properties to absorb and retain P. Secondly, incorporating native woodchips into woodchip bioreactors systems potentially offers a sustainable and culturally respected alternative to conventional wood chips, aligning with Māori values and tikanga

year: 2023