title: Lagrangian measurements of turbulent dissipation over a shallow tidal ﬂat from pulse coherent Acoustic Doppler Profilers

authors: Mullarney, Julia C.

subjects: drifters

abstract: We present high resolution (25 mm spatial, 8 Hz temporal) profiles of velocity measured over a shallow tidal flat using pulse-coherent Acoustic Doppler Profilers mounted on surface drifters. The use of Lagrangian measurements mitigated the problem of resolving velocity ambiguities, a problem which often limits the application of high-resolution pulse-coherent profilers. Turbulent dissipation rates were estimated from second-order structure functions of measured velocity. Drifters were advected towards, and subsequently trapped on, a convergent surface front which marked the edge of a freshwater plume. Measured dissipation rates increased as a drifter deployed within the plume approached the front. A drifter then propagated with and along the front as the fresh plume spread across the tidal flats. Near-surface turbulent dissipation measured at the front roughly matched a theoretical mean-shear-cubed relationship, whereas dissipation measured in the stratified plume behind the front was suppressed. After removal of estimates affected by surface waves, near-bed dissipation matched the velocity cubed relationship, although scatter was substantial. Dissipation rates appeared to be enhanced when the drifter propagated across small subtidal channels.

text: Lagrangian measurements of turbulent dissipation over a shallow tidal ﬂat from pulse coherent Acoustic Doppler Profilers We present high resolution (25 mm spatial, 8 Hz temporal) profiles of velocity measured over a shallow tidal flat using pulse-coherent Acoustic Doppler Profilers mounted on surface drifters. The use of Lagrangian measurements mitigated the problem of resolving velocity ambiguities, a problem which often limits the application of high-resolution pulse-coherent profilers. Turbulent dissipation rates were estimated from second-order structure functions of measured velocity. Drifters were advected towards, and subsequently trapped on, a convergent surface front which marked the edge of a freshwater plume. Measured dissipation rates increased as a drifter deployed within the plume approached the front. A drifter then propagated with and along the front as the fresh plume spread across the tidal flats. Near-surface turbulent dissipation measured at the front roughly matched a theoretical mean-shear-cubed relationship, whereas dissipation measured in the stratified plume behind the front was suppressed. After removal of estimates affected by surface waves, near-bed dissipation matched the velocity cubed relationship, although scatter was substantial. Dissipation rates appeared to be enhanced when the drifter propagated across small subtidal channels.

year: 2012

title: Cumulative impacts assessment along a large river, using brown bullhead catfish (ameiurus nebulosus) populations

authors: West, David William

subjects: fish health

abstract: The effects of point-source and diffuse discharges on resident populations of brown bullhead catfish (Ameiurus nebulosus (LeSueur, 1819)) in the Waikato River (New Zealand) were assessed at sites both upstream and downstream of point-source discharges. At each site, the population parameters, relative abundance, age structure, and individual indices, such as condition factor, organ (gonad, liver, and spleen) to somatic weight ratios, and number and size of follicles per female, were assessed. Physiological (blood), biochemical (hepatic ethoxyresorufin-O-deethylase [EROD] and plasma steroids), and other indicators (bile chemistry and liver metals) of exposure or response also were measured. No impacts on brown bullhead health were obvious at individual geothermal, municipal sewage, or thermal discharge sites or cumulatively along the river. Brown bullhead from the bleached kraft mill effluent site showed elevated levels of EROD, decreased numbers of red blood cells, increased numbers of white blood cells, and depressed levels of sex steroids. However, growth rates, condition factor, age structure, and gonadosomatic index suggest that discharges with significant heat or nutrients benefit catfish despite physiological impairment at one site. Consideration of brown bullhead population-level responses to discharges in a monitoring framework revealed three different population-level response patterns resulting from the point-source discharges.

text: Cumulative impacts assessment along a large river, using brown bullhead catfish (ameiurus nebulosus) populations The effects of point-source and diffuse discharges on resident populations of brown bullhead catfish (Ameiurus nebulosus (LeSueur, 1819)) in the Waikato River (New Zealand) were assessed at sites both upstream and downstream of point-source discharges. At each site, the population parameters, relative abundance, age structure, and individual indices, such as condition factor, organ (gonad, liver, and spleen) to somatic weight ratios, and number and size of follicles per female, were assessed. Physiological (blood), biochemical (hepatic ethoxyresorufin-O-deethylase [EROD] and plasma steroids), and other indicators (bile chemistry and liver metals) of exposure or response also were measured. No impacts on brown bullhead health were obvious at individual geothermal, municipal sewage, or thermal discharge sites or cumulatively along the river. Brown bullhead from the bleached kraft mill effluent site showed elevated levels of EROD, decreased numbers of red blood cells, increased numbers of white blood cells, and depressed levels of sex steroids. However, growth rates, condition factor, age structure, and gonadosomatic index suggest that discharges with significant heat or nutrients benefit catfish despite physiological impairment at one site. Consideration of brown bullhead population-level responses to discharges in a monitoring framework revealed three different population-level response patterns resulting from the point-source discharges.

year: 2006

title: Ethics in Maori research: Working paper

authors: Cram, Fiona

subjects: Maori

abstract: When we think about what we are doing as researchers, one of our main tasks is to acquire knowledge. For some researchers their task begins and ends there. Knowledge is viewed as cumulative, that by adding to some knowledge pool we will one day be able to put the component parts together and discover universal laws. Many researchers also assume that the knowledge they have collected is objective, value-free and apolitical. This is part of psychologists’ ‘physics envy’. A Maori view of knowledge is very different from this. For Maori the purpose of knowledge is to uphold the interests and the mana of the group; it serves the community. Researchers are not building up their own status; they are fighting for the betterment of their iwi and for Maori people in general.

text: Ethics in Maori research: Working paper When we think about what we are doing as researchers, one of our main tasks is to acquire knowledge. For some researchers their task begins and ends there. Knowledge is viewed as cumulative, that by adding to some knowledge pool we will one day be able to put the component parts together and discover universal laws. Many researchers also assume that the knowledge they have collected is objective, value-free and apolitical. This is part of psychologists’ ‘physics envy’. A Maori view of knowledge is very different from this. For Maori the purpose of knowledge is to uphold the interests and the mana of the group; it serves the community. Researchers are not building up their own status; they are fighting for the betterment of their iwi and for Maori people in general.

year: 1993