title: Identifying dissolved oxygen variability and stress in tidal freshwater streams of northern New Zealand

authors: Wilding, Thomas K.

subjects: dissolved oxygen

abstract: Tidal streams are ecologically important components of lotic network, and we identify dissolved oxygen (DO) depletion as a potentially important stressor in freshwater tidal streams of northern New Zealand. Other studies have examined temporal DO variability within rivers and we build on this by examining variability between streams as a basis for regional-scale predictors of risk for DO stress. Diel DO variability in these streams was driven by: (1) photosynthesis by aquatic plants and community respiration which produced DO maxima in the afternoon and minima early morning (range, 0.6–4.7 g/m³) as a product of the solar cycle and (2) tidal variability as a product of the lunar cycle, including saline intrusions with variable DO concentrations plus a small residual effect on freshwater DO for low-velocity streams. The lowest DO concentrations were observed during March (early autumn) when water temperatures and macrophyte biomass were high. Spatial comparisons indicated that lowgradient tidal streams were at greater risk of DO depletions harmful to aquatic life. Tidal influence was stronger in low-gradient streams, which typically drain more developed catchments, have lower reaeration potential and offer conditions more suitable for aquatic plant proliferation. Combined, these characteristics supported a simple method based on the extent of low-gradient channel for identifying coastal streams at risk of DO depletion. High-risk streams can then be targeted for riparian planting, nutrient limits and water allocation controls to reduce potential ecological stress.

text: Identifying dissolved oxygen variability and stress in tidal freshwater streams of northern New Zealand Tidal streams are ecologically important components of lotic network, and we identify dissolved oxygen (DO) depletion as a potentially important stressor in freshwater tidal streams of northern New Zealand. Other studies have examined temporal DO variability within rivers and we build on this by examining variability between streams as a basis for regional-scale predictors of risk for DO stress. Diel DO variability in these streams was driven by: (1) photosynthesis by aquatic plants and community respiration which produced DO maxima in the afternoon and minima early morning (range, 0.6–4.7 g/m³) as a product of the solar cycle and (2) tidal variability as a product of the lunar cycle, including saline intrusions with variable DO concentrations plus a small residual effect on freshwater DO for low-velocity streams. The lowest DO concentrations were observed during March (early autumn) when water temperatures and macrophyte biomass were high. Spatial comparisons indicated that lowgradient tidal streams were at greater risk of DO depletions harmful to aquatic life. Tidal influence was stronger in low-gradient streams, which typically drain more developed catchments, have lower reaeration potential and offer conditions more suitable for aquatic plant proliferation. Combined, these characteristics supported a simple method based on the extent of low-gradient channel for identifying coastal streams at risk of DO depletion. High-risk streams can then be targeted for riparian planting, nutrient limits and water allocation controls to reduce potential ecological stress.

year: 2012

title: Stratigraphic columns for the Neogene succession exposed in central parts of Hawke’s Bay Basin, eastern North Island, New Zealand

authors: Kamp, Peter J.J.

subjects: lithostratigraphy

abstract: This report is a compilation of stratigraphic columns for geological sections and outcrops of Neogene sedimentary units in central parts of Hawke’s Bay Basin, eastern North Island, New Zealand. The columns have been prepared as part of a basin analysis investigation undertaken by the Sedimentary and Petroleum Geology Research Group in the Department of Earth and Ocean Sciences at the University of Waikato and have been compiled into a common format from six recent MSc and PhD theses to make the information more readily available, principally to assist hydrocarbon exploration activities in the region. The columns represent a level of detail underpinning a rationalized lithostratigraphy of the Neogene basin fill. The systematic lithostratigraphic description of the basin fill is given in a companion report (Bland et al. 2007).

text: Stratigraphic columns for the Neogene succession exposed in central parts of Hawke’s Bay Basin, eastern North Island, New Zealand This report is a compilation of stratigraphic columns for geological sections and outcrops of Neogene sedimentary units in central parts of Hawke’s Bay Basin, eastern North Island, New Zealand. The columns have been prepared as part of a basin analysis investigation undertaken by the Sedimentary and Petroleum Geology Research Group in the Department of Earth and Ocean Sciences at the University of Waikato and have been compiled into a common format from six recent MSc and PhD theses to make the information more readily available, principally to assist hydrocarbon exploration activities in the region. The columns represent a level of detail underpinning a rationalized lithostratigraphy of the Neogene basin fill. The systematic lithostratigraphic description of the basin fill is given in a companion report (Bland et al. 2007).

year: 2007

title: Whanaungatanga: an illustration of the importance of cultural context

authors: McNatty, William

subjects: Te reo Māori

abstract: The word 'whanaungatanga' is often used by people who lack an intimate understanding of the philosophical base in Māori culture out of which it emerges. Thus, it is sometimes used simply to describe the camaraderie that can be associated with team sports or with reference to the 'glue' that connects people to one another socially. This is not necessarily a problem in itself. After all, change and development in the lexicon is a characteristic of living languages. However, real problems can emerge where words become divorced from their cultural roots to such an extent that two speakers using the same word can completely fail to understand one another. It is argued here that this is what can happen when Māori words, such as 'whanaungatanga', are used in the context of modelling in the social sciences, particularly where that modelling is conducted in the context of Western social and cultural values. In particular, the essential spiritual dimension of whanaungatanga may be overlooked or misunderstood.

text: Whanaungatanga: an illustration of the importance of cultural context The word 'whanaungatanga' is often used by people who lack an intimate understanding of the philosophical base in Māori culture out of which it emerges. Thus, it is sometimes used simply to describe the camaraderie that can be associated with team sports or with reference to the 'glue' that connects people to one another socially. This is not necessarily a problem in itself. After all, change and development in the lexicon is a characteristic of living languages. However, real problems can emerge where words become divorced from their cultural roots to such an extent that two speakers using the same word can completely fail to understand one another. It is argued here that this is what can happen when Māori words, such as 'whanaungatanga', are used in the context of modelling in the social sciences, particularly where that modelling is conducted in the context of Western social and cultural values. In particular, the essential spiritual dimension of whanaungatanga may be overlooked or misunderstood.

year: 2002-02