title: Ecological effects of artificial mixing in Lake Rotoehu

authors: McBride, Chris G.

abstract: Lake Rotoehu is a eutrophic, moderately large (795 ha), shallow (mean depth 8.2 m), polymictic lake in the Rotorua/Te Arawa lake district. Land use intensification, water level changes, and nutrient-rich geothermal inflows are some of the factors which may have contributed to severe cyanobacteria blooms over the past 20 years.
Bay of Plenty Regional Council (BoPRC) is charged with maintaining the ecosystem health of Lake Rotoehu. In 2007 BoPRC published the Lake Rotoehu Action Plan, outlining multiple restoration initiatives to reduce nutrient loading to the lake. Among these initiatives was a trial of artificial mixing to increase vertical circulation within the water column, preventing the formation of stratification. Two water column mixing devices were deployed on the lake bed of Lake Rotoehu from November 2012 to June 2014 (and are ongoing). These devices force compressed air through a diffuser near the bottom of the lake water column in the central lake basin. Buoyancy caused by the rising bubbles draws water from the bottom of the lake up through large vertical cylinders to the surface, where the entrained water is subsequently directed horizontally along the water surface. The University of Waikato was contracted to monitor the physical (temperature and dissolved oxygen), chemical (nutrients), and biological (phytoplankton and zooplankton) effects of the mixing devices on the lake. This work encompassed a range of instrumentation, laboratory analyses, and species enumeration from water samples.
In addition, an evaluation of the area of effect and strength of current generated by the mixing devices was conducted by the National Institute of Water and Atmospheric Research (NIWA), the results of which are reported here. Rhodamine dye tracer injected into the northern arm of the southern mixing device revealed that cooler hypolimnetic water was being brought to the surface. A component of the water entrained in this plume flowed away from the mixing device for at least 90 m. Parts of the plume also detrained from it, sinking towards the thermocline. Plumes from the mixing devices were tracked by Acoustic Doppler Current Meters (ADCM) or Profilers. The ADCM data revealed that the plume gradually dispersed laterally with increasing distance from the mixing device, and plume velocities were not elevated above background levels at c. 70 m from the mixing device. Although current velocities measured in the plume were generally low (<1 cm s⁻¹ to 25 cm s⁻¹; average 5.5 cm s⁻¹) they could be clearly distinguished from wind driven currents. 
Changes to the water column thermal profile were observed adjacent to the mixing devices, however, modification of the water column temperature structure across the lake (i.e., greater than a hundred metres from the devices) was not observed. Interpretations of the effect of the aeration devices was somewhat confounded by the period prior to installation of the machines (summer 2012) being cold and windy relative to weather conditions during the period of device deployment, which were unusually hot and dry (summer 2013 and 2014). These conditions resulted in Lake Rotoehu being stratified more often and strongly than in the summer prior to device installation. Additional factors affecting the aeration device operation are discussed in the report.
Analyses of nutrient concentrations, water clarity, and trophic status indicators have shown some improvement of Lake Rotoehu over recent years. However, the Trophic Level Index (TLI) has not yet met the target of 3.9 specified by the Rotoehu Action Plan. Water quality assessed by these indicators was comparatively good in 2012 - June 2014 despite the sustained periods of thermal stratification that contributed to significant oxygen depletion in bottom waters.
Localised effects of mixing included homogenisation of the cyanobacterial community through the water column and a decrease in the Bray-Curtis similarity index of the plankton community between mixing sites (i.e. near the aeration device) and controls (i.e. several hundred metres away from the mixing device). These results are consistent with physical observations of localised changes in thermal structure around the aeration devices. No significant changes occurred in plankton community composition at the whole-lake scale during aerator operation during the 2013 and 2014. By contrast, plankton community composition showed large seasonal and inter-annual variability including presence of invasive species.
Results suggest that the mixing devices installed in Lake Rotoehu are able to draw hypolimnetic water to the surface. The resulting horizontal plume rapidly becomes mixed with surface waters over distances of 50-60 m from the aerator but can also be tracked as it plunges towards the thermocline at these distances. Some localised effects were detected near the aerators but there were no detectable lake-scale effects. By contrast, there have been progressive improvements in water quality at a whole-lake scale over recent years and these may relate to alum dosing of the major geothermal inflow to the lake, weed harvesting and initial decreases in external nutrient inputs in response to changes in land use and land-use practices. Further monitoring will help clarify these observations, and an additional year of mixing device deployment aims to improve operational efficiency of the devices and quantify effects of proposed increases in air flow rates.

text: Ecological effects of artificial mixing in Lake Rotoehu Lake Rotoehu is a eutrophic, moderately large (795 ha), shallow (mean depth 8.2 m), polymictic lake in the Rotorua/Te Arawa lake district. Land use intensification, water level changes, and nutrient-rich geothermal inflows are some of the factors which may have contributed to severe cyanobacteria blooms over the past 20 years.
Bay of Plenty Regional Council (BoPRC) is charged with maintaining the ecosystem health of Lake Rotoehu. In 2007 BoPRC published the Lake Rotoehu Action Plan, outlining multiple restoration initiatives to reduce nutrient loading to the lake. Among these initiatives was a trial of artificial mixing to increase vertical circulation within the water column, preventing the formation of stratification. Two water column mixing devices were deployed on the lake bed of Lake Rotoehu from November 2012 to June 2014 (and are ongoing). These devices force compressed air through a diffuser near the bottom of the lake water column in the central lake basin. Buoyancy caused by the rising bubbles draws water from the bottom of the lake up through large vertical cylinders to the surface, where the entrained water is subsequently directed horizontally along the water surface. The University of Waikato was contracted to monitor the physical (temperature and dissolved oxygen), chemical (nutrients), and biological (phytoplankton and zooplankton) effects of the mixing devices on the lake. This work encompassed a range of instrumentation, laboratory analyses, and species enumeration from water samples.
In addition, an evaluation of the area of effect and strength of current generated by the mixing devices was conducted by the National Institute of Water and Atmospheric Research (NIWA), the results of which are reported here. Rhodamine dye tracer injected into the northern arm of the southern mixing device revealed that cooler hypolimnetic water was being brought to the surface. A component of the water entrained in this plume flowed away from the mixing device for at least 90 m. Parts of the plume also detrained from it, sinking towards the thermocline. Plumes from the mixing devices were tracked by Acoustic Doppler Current Meters (ADCM) or Profilers. The ADCM data revealed that the plume gradually dispersed laterally with increasing distance from the mixing device, and plume velocities were not elevated above background levels at c. 70 m from the mixing device. Although current velocities measured in the plume were generally low (<1 cm s⁻¹ to 25 cm s⁻¹; average 5.5 cm s⁻¹) they could be clearly distinguished from wind driven currents. 
Changes to the water column thermal profile were observed adjacent to the mixing devices, however, modification of the water column temperature structure across the lake (i.e., greater than a hundred metres from the devices) was not observed. Interpretations of the effect of the aeration devices was somewhat confounded by the period prior to installation of the machines (summer 2012) being cold and windy relative to weather conditions during the period of device deployment, which were unusually hot and dry (summer 2013 and 2014). These conditions resulted in Lake Rotoehu being stratified more often and strongly than in the summer prior to device installation. Additional factors affecting the aeration device operation are discussed in the report.
Analyses of nutrient concentrations, water clarity, and trophic status indicators have shown some improvement of Lake Rotoehu over recent years. However, the Trophic Level Index (TLI) has not yet met the target of 3.9 specified by the Rotoehu Action Plan. Water quality assessed by these indicators was comparatively good in 2012 - June 2014 despite the sustained periods of thermal stratification that contributed to significant oxygen depletion in bottom waters.
Localised effects of mixing included homogenisation of the cyanobacterial community through the water column and a decrease in the Bray-Curtis similarity index of the plankton community between mixing sites (i.e. near the aeration device) and controls (i.e. several hundred metres away from the mixing device). These results are consistent with physical observations of localised changes in thermal structure around the aeration devices. No significant changes occurred in plankton community composition at the whole-lake scale during aerator operation during the 2013 and 2014. By contrast, plankton community composition showed large seasonal and inter-annual variability including presence of invasive species.
Results suggest that the mixing devices installed in Lake Rotoehu are able to draw hypolimnetic water to the surface. The resulting horizontal plume rapidly becomes mixed with surface waters over distances of 50-60 m from the aerator but can also be tracked as it plunges towards the thermocline at these distances. Some localised effects were detected near the aerators but there were no detectable lake-scale effects. By contrast, there have been progressive improvements in water quality at a whole-lake scale over recent years and these may relate to alum dosing of the major geothermal inflow to the lake, weed harvesting and initial decreases in external nutrient inputs in response to changes in land use and land-use practices. Further monitoring will help clarify these observations, and an additional year of mixing device deployment aims to improve operational efficiency of the devices and quantify effects of proposed increases in air flow rates.

year: 2015

title: Professor Predrag Bajčetić: The Life And The Method

authors: Ladevac, Mihailo

subjects: Predrag Bajcetic

abstract: The facts show that more than 300 actors have been educated by Professor Predrag Bajčetić, through his own acting training method, not just in Serbia but in other ex-Yugoslav republics and Norway as well. Professor Bajčetić also has directed a vast number of theatre plays, television films and radio dramas, and he has written more than thirty theoretical articles, essays and reviews. However, there are very few writings about him in Serbian and almost none in English. With this thesis I am presenting his work to an English-speaking reader, as I strongly believe that the Professor’s acting training method, which prepares an actor for all different types of theatre, should be known to a wider audience.
This thesis summarises the findings collected through biographical research methods. The research was designed in three parts. The first part was an interview with Professor Bajčetić to provide data useful for understanding the construction of the acting training method, as well as his overall mentorship. The second part was a survey with the Professor’s former students; two were chosen from every class he taught since 1971. The third part was the analysis of the Professor’s previously given interviews and analysis of some of his published articles and essays, which helped me to collect useful data for this research. The information I have gathered shed light on the Professor’s life circumstances, his acting training method and his mentorship, and is of immense value in understanding his influence, and the influence of his method on his former students, as well as the general significance of Professor Bajčetić in Serbian social and artistic contexts.
Regarding the method itself, it will be seen how the political atmosphere was one of the biggest obstacles in the creation process from 1956 until Professor Bajčetić’s retirement in 2001. As the Professor had participated in all important political events and protests in Yugoslavia and Serbia since 1956, his work was always strictly controlled. Despite the fact that he could not talk or write freely about some pedagogical innovations, he had the chance to share his ideas in the United States of America and Norway and to test them away from the politically controlled regime in his own country. Nevertheless, in his own country he was ‘removed’ from his public work as a director. To be more precise, he was completely excluded from further work as a director in theatre, radio and television. Even though his writings were published, they were all strictly theoretical. Therefore, his work was principally pedagogical. However, his influence on his students was sufficiently significant to spread his ideas through them.
The findings undoubtedly show the Professor’s enormous influence on his former students. Their testimonies in the survey state that he always expected their maximum efforts. Even when they would perform on the highest levels, giving their utmost, the Professor would ask for more. He was very strict but gentle at the same time, the majority of participants stated. He was always there to support them even in the most turbulent political periods in the former Yugoslavia and Milošević’s Serbia. The only question that was answered unanimously by all participants was regarding his dedication to his students; he always stayed longer at the class and worked, very often, with his students in his own free time. As the greater group of participants stated, Professor Bajčetić shaped his student’s personalities; to bring them to the view that morality and the protection of national and cultural values are the obligation of an artist. Therefore, he taught his former students to act and react in all important political and cultural events as they, as actors, would have a considerable public influence.
As for the importance of Professor Bajčetić’s acting training method, his former students acknowledged the method as the most significant in their acting careers. From the method, they chose work on Chekhov’s plays and on the Tables of Nations from the Bible as the most important from Year One. In the part of the survey considering Year Two of the method, a greater number of participants chose to work on characters from Dostoyevsky’s novels and Shakespeare’s comedies. As for Year Three, work on characters from Ancient Greek and Shakespeare’s tragedies was chosen as most useful for their future work in theatre. They noticed that those tasks taught them to be emotional but ‘truthful’ on stage. Also it was drawn from the survey that the work on those exercises introduced to them the importance of theatre and developed in them a great deal of respect for it. However, it was clearly stated by all participants that the work in Year Three of the acting training method was the most significant for their work in theatre.
My research investigates the impact of Professor Predrag Bajčetić and his acting training method. All the data collected through the research provides sufficient proof of the Professor’s pre-eminence in the social and artistic context, both in former Yugoslavia and contemporary Serbia. His importance is demonstrated not only through his mentorship and his education of more than 300 actors – some of whom became the most important cultural and theatre people (such as ministers of culture and heads of main theatres in Serbia) – but also through his political activity in his country. Moreover, this thesis presents the most important tasks from his acting method, chosen by his former students and described by him throughout our interview, as well as his key writings regarding the field of acting pedagogy.

text: Professor Predrag Bajčetić: The Life And The Method The facts show that more than 300 actors have been educated by Professor Predrag Bajčetić, through his own acting training method, not just in Serbia but in other ex-Yugoslav republics and Norway as well. Professor Bajčetić also has directed a vast number of theatre plays, television films and radio dramas, and he has written more than thirty theoretical articles, essays and reviews. However, there are very few writings about him in Serbian and almost none in English. With this thesis I am presenting his work to an English-speaking reader, as I strongly believe that the Professor’s acting training method, which prepares an actor for all different types of theatre, should be known to a wider audience.
This thesis summarises the findings collected through biographical research methods. The research was designed in three parts. The first part was an interview with Professor Bajčetić to provide data useful for understanding the construction of the acting training method, as well as his overall mentorship. The second part was a survey with the Professor’s former students; two were chosen from every class he taught since 1971. The third part was the analysis of the Professor’s previously given interviews and analysis of some of his published articles and essays, which helped me to collect useful data for this research. The information I have gathered shed light on the Professor’s life circumstances, his acting training method and his mentorship, and is of immense value in understanding his influence, and the influence of his method on his former students, as well as the general significance of Professor Bajčetić in Serbian social and artistic contexts.
Regarding the method itself, it will be seen how the political atmosphere was one of the biggest obstacles in the creation process from 1956 until Professor Bajčetić’s retirement in 2001. As the Professor had participated in all important political events and protests in Yugoslavia and Serbia since 1956, his work was always strictly controlled. Despite the fact that he could not talk or write freely about some pedagogical innovations, he had the chance to share his ideas in the United States of America and Norway and to test them away from the politically controlled regime in his own country. Nevertheless, in his own country he was ‘removed’ from his public work as a director. To be more precise, he was completely excluded from further work as a director in theatre, radio and television. Even though his writings were published, they were all strictly theoretical. Therefore, his work was principally pedagogical. However, his influence on his students was sufficiently significant to spread his ideas through them.
The findings undoubtedly show the Professor’s enormous influence on his former students. Their testimonies in the survey state that he always expected their maximum efforts. Even when they would perform on the highest levels, giving their utmost, the Professor would ask for more. He was very strict but gentle at the same time, the majority of participants stated. He was always there to support them even in the most turbulent political periods in the former Yugoslavia and Milošević’s Serbia. The only question that was answered unanimously by all participants was regarding his dedication to his students; he always stayed longer at the class and worked, very often, with his students in his own free time. As the greater group of participants stated, Professor Bajčetić shaped his student’s personalities; to bring them to the view that morality and the protection of national and cultural values are the obligation of an artist. Therefore, he taught his former students to act and react in all important political and cultural events as they, as actors, would have a considerable public influence.
As for the importance of Professor Bajčetić’s acting training method, his former students acknowledged the method as the most significant in their acting careers. From the method, they chose work on Chekhov’s plays and on the Tables of Nations from the Bible as the most important from Year One. In the part of the survey considering Year Two of the method, a greater number of participants chose to work on characters from Dostoyevsky’s novels and Shakespeare’s comedies. As for Year Three, work on characters from Ancient Greek and Shakespeare’s tragedies was chosen as most useful for their future work in theatre. They noticed that those tasks taught them to be emotional but ‘truthful’ on stage. Also it was drawn from the survey that the work on those exercises introduced to them the importance of theatre and developed in them a great deal of respect for it. However, it was clearly stated by all participants that the work in Year Three of the acting training method was the most significant for their work in theatre.
My research investigates the impact of Professor Predrag Bajčetić and his acting training method. All the data collected through the research provides sufficient proof of the Professor’s pre-eminence in the social and artistic context, both in former Yugoslavia and contemporary Serbia. His importance is demonstrated not only through his mentorship and his education of more than 300 actors – some of whom became the most important cultural and theatre people (such as ministers of culture and heads of main theatres in Serbia) – but also through his political activity in his country. Moreover, this thesis presents the most important tasks from his acting method, chosen by his former students and described by him throughout our interview, as well as his key writings regarding the field of acting pedagogy.

year: 2015

title: Te Piringa

authors: Dickson, Matiu

abstract: Māori have an oral tradition, that is, the transfer of knowledge within and between generations, which was carried out orally by way of story-telling or the more formal speech-making. Ngā korero purākau are the stories and whaikōrero is formal talking on the marae or ancestral gathering places of Māori people. The value of public speaking is expressed in the saying: Ko te kōrerote kai a te Rangatira – (The chiefs thrive on talking and debating). This article looks at the transfer of knowledge to the next generation.

text: Te Piringa Māori have an oral tradition, that is, the transfer of knowledge within and between generations, which was carried out orally by way of story-telling or the more formal speech-making. Ngā korero purākau are the stories and whaikōrero is formal talking on the marae or ancestral gathering places of Māori people. The value of public speaking is expressed in the saying: Ko te kōrerote kai a te Rangatira – (The chiefs thrive on talking and debating). This article looks at the transfer of knowledge to the next generation.

year: 2010