title: Ecology of the invertebrate predatory fauna across Centre Bank, Tauranga Harbour

authors: Putt, Fiona Gloria

subjects: Centre Bank

abstract: The distribution, abundance, population size structure and behaviour of three common invertebrate predators were studied on Centre Bank, the flood-tidal delta of Tauranga Harbour. The study assessed the role of the predators in controlling the distribution and abundance of bivalve shellfish and provided information concerning the biology of Centre Bank for Port of Tauranga Ltd.
Two broad-scale surveys were conducted to describe the broad-scale spatial patterns of Patiriella regularis, Coscinasterias calamaria and Cominella adspersa. Results found P. regularis was the numerically dominant species across Centre Bank and it maintained a widespread distribution over the sampling period. C. calamaria was of low abundance and typically exhibited a patchy distribution. C. adspersa was also found to be of low abundance and similarly distributed as C. calamaria. Size structures of all 3 species comprised mostly adults in both surveys.
Temporal monitoring at finer scales was undertaken, two-monthly, to describe small-scale spatial patterns. P. regularis was found at similar densities to that of the large-scale surveys and it was the most prevalent species across the grid; C. calamaria was present at higher abundances within a small patch of the grid and appeared stable over time. C. adspersa was initially absent from the grid, but became more abundant and widespead over the 9 month sampling period.
Investigations included monitoring the natural movement behaviour of C. adspersa in relation to tidal currents and the body condition. Results showed the directions moved and distances displaced by C. adspersa may be influenced by the rate and direction of current movement and therefore potentially influencing the dispersal ability of C. adspersa, in relation to available prey. An experiment to determine the body condition of C. adspersa in the field suggested that food deprivation may be less detrimental than first realised, or that C. adspersa is able to feed on a greater variety of food types than known of.
Little evidence was found that indicated predation was an important mechanism controlling bivalve populations across Centre Bank. However, predators may be potentially important as scavengers of decaying or dead organisms. Their predatory activities may also provide shell substrate for macroalgae, and this, in combination with dense aggregations of C. calamaria, appeared to provide habitat for small fishes.

text: Ecology of the invertebrate predatory fauna across Centre Bank, Tauranga Harbour The distribution, abundance, population size structure and behaviour of three common invertebrate predators were studied on Centre Bank, the flood-tidal delta of Tauranga Harbour. The study assessed the role of the predators in controlling the distribution and abundance of bivalve shellfish and provided information concerning the biology of Centre Bank for Port of Tauranga Ltd.
Two broad-scale surveys were conducted to describe the broad-scale spatial patterns of Patiriella regularis, Coscinasterias calamaria and Cominella adspersa. Results found P. regularis was the numerically dominant species across Centre Bank and it maintained a widespread distribution over the sampling period. C. calamaria was of low abundance and typically exhibited a patchy distribution. C. adspersa was also found to be of low abundance and similarly distributed as C. calamaria. Size structures of all 3 species comprised mostly adults in both surveys.
Temporal monitoring at finer scales was undertaken, two-monthly, to describe small-scale spatial patterns. P. regularis was found at similar densities to that of the large-scale surveys and it was the most prevalent species across the grid; C. calamaria was present at higher abundances within a small patch of the grid and appeared stable over time. C. adspersa was initially absent from the grid, but became more abundant and widespead over the 9 month sampling period.
Investigations included monitoring the natural movement behaviour of C. adspersa in relation to tidal currents and the body condition. Results showed the directions moved and distances displaced by C. adspersa may be influenced by the rate and direction of current movement and therefore potentially influencing the dispersal ability of C. adspersa, in relation to available prey. An experiment to determine the body condition of C. adspersa in the field suggested that food deprivation may be less detrimental than first realised, or that C. adspersa is able to feed on a greater variety of food types than known of.
Little evidence was found that indicated predation was an important mechanism controlling bivalve populations across Centre Bank. However, predators may be potentially important as scavengers of decaying or dead organisms. Their predatory activities may also provide shell substrate for macroalgae, and this, in combination with dense aggregations of C. calamaria, appeared to provide habitat for small fishes.

year: 1996

title: Assessment of the performance of a turbulence closure model: along the tidally-influenced Kaipara River to the estuary, NZ

authors: Dejeans, Bérengère S.

subjects: turbulence

abstract: The success of many coastal management projects hinges on the ability to predict the dispersal and settling of sediment particles. Hydrodynamic models have enabled the efficient simulation of sediment transport scenarios at large spatial scales and long time scales. However, these models have limited predictive capacity owing to an incomplete understanding of the processes involved. Turbulence has been shown to have a substantial influence on sediment transport by influencing flocculation (i.e. aggregation of particles), hence driving the behaviour of particles (e.g. deposition, erosion, mixing). Turbulence tends to promote aggregation at low shear stresses and cause floc breakups at high shear stresses. However, despite the key role of turbulence in coastal modelling, there is not a unique approach but several methods to describe turbulence, each based on a different combination of assumptions. We present modelling results exploring the performance of one closure scheme implemented in a hydrodynamic and sediment transport model, Delft3D. The assessment of the performance of the model is based on comparisons with measured data collected in the heavily sediment-laden Kaipara river, New Zealand. Data was collected in October 2013 using Lagrangian “flocdrifter” platforms released at multiple locations to capture both hydrodynamic and sediment data. In general the model was found to be able to reproduce the right order of magnitude of dissipation rates. However, turbulence characteristics in some sections of the river, usually in the vicinity of abrupt bends, are relatively poorly reproduced. Future work will aim to use the present model to improve the conceptual understanding of fundamental physical processes, in particular the effect of turbulence on flocculation, and floc formation and breakup in estuarine and riverine systems.

text: Assessment of the performance of a turbulence closure model: along the tidally-influenced Kaipara River to the estuary, NZ The success of many coastal management projects hinges on the ability to predict the dispersal and settling of sediment particles. Hydrodynamic models have enabled the efficient simulation of sediment transport scenarios at large spatial scales and long time scales. However, these models have limited predictive capacity owing to an incomplete understanding of the processes involved. Turbulence has been shown to have a substantial influence on sediment transport by influencing flocculation (i.e. aggregation of particles), hence driving the behaviour of particles (e.g. deposition, erosion, mixing). Turbulence tends to promote aggregation at low shear stresses and cause floc breakups at high shear stresses. However, despite the key role of turbulence in coastal modelling, there is not a unique approach but several methods to describe turbulence, each based on a different combination of assumptions. We present modelling results exploring the performance of one closure scheme implemented in a hydrodynamic and sediment transport model, Delft3D. The assessment of the performance of the model is based on comparisons with measured data collected in the heavily sediment-laden Kaipara river, New Zealand. Data was collected in October 2013 using Lagrangian “flocdrifter” platforms released at multiple locations to capture both hydrodynamic and sediment data. In general the model was found to be able to reproduce the right order of magnitude of dissipation rates. However, turbulence characteristics in some sections of the river, usually in the vicinity of abrupt bends, are relatively poorly reproduced. Future work will aim to use the present model to improve the conceptual understanding of fundamental physical processes, in particular the effect of turbulence on flocculation, and floc formation and breakup in estuarine and riverine systems.

year: 2017

title: Outdoor education: Opportunities provided by a place based approach

authors: Brown, Mike

subjects: place-based

abstract: This paper calls for educators to consider the role that ‘place’ has in outdoor education experiences. It is suggested that greater emphasis and acknowledgment be given to ‘place(s)’ and how they may help students make sense of both their personal and communal identity. The paper is interwoven with a narrative from the author’s experiences of working with Pākehā and Māori students on a course that consciously utilised a ‘place-based’ approach to teaching and learning. The paper challenges the conception that outdoor education requires ‘high-impact’ adventurous activities, instead suggesting that we seek to develop a modest pedagogy which acknowledges our relationships with place(s) as a way to understand who we are , how we connect to others and how we both give and take meanings from the places in which we live and learn. These issues have potential implications for educators and programme designers.

text: Outdoor education: Opportunities provided by a place based approach This paper calls for educators to consider the role that ‘place’ has in outdoor education experiences. It is suggested that greater emphasis and acknowledgment be given to ‘place(s)’ and how they may help students make sense of both their personal and communal identity. The paper is interwoven with a narrative from the author’s experiences of working with Pākehā and Māori students on a course that consciously utilised a ‘place-based’ approach to teaching and learning. The paper challenges the conception that outdoor education requires ‘high-impact’ adventurous activities, instead suggesting that we seek to develop a modest pedagogy which acknowledges our relationships with place(s) as a way to understand who we are , how we connect to others and how we both give and take meanings from the places in which we live and learn. These issues have potential implications for educators and programme designers.

year: 2008