title: Ecological monitoring of artificial destratification effects in Lake Rotoehu: 2014-2015

authors: Tempero, Grant Wayne

abstract: Lake Rotoehu is a shallow (mean depth 8 m), polymictic eutrophic lake in the Rotorua lakes district. Catchment land use intensification has contributed to a decline in water quality and persistent cyanobacterial algal blooms for the past 20 years and combines with a background of nutrient-rich geothermal inflows. Two artificial mixing devices were deployed in Lake Rotoehu in the spring of 2012 by the Bay of Plenty Regional Council with the aim of preventing lake thermal stratification. They were previously operated over the summer-autumn periods of 2012-13 and 2013-14 and their effects were monitored on a monthly basis until June 2014. The devices force compressed air through a diffuser near the lake bottom, and into three large vertical cylinders. Buoyancy, caused by the rising bubbles, draws water from the bottom of the lake up through the vertical cylinders and directs it horizontally into the surface mixed layer (epilimnion). This causes mixing of thermally distinct layers of the water column, and is designed to inhibit stratification and prevent hypolimnetic deoxygenation. Results from previous monitoring indicate that the mixing devices produced a limited, localised mixing effect, but had no influence on whole lake ecology. With a view to improving performance, modifications, including channelling all air through a single mixing device and increasing compressor output, were effected in preparation for the 2014-15 summer-autumn seasons. The University of Waikato was contracted by the Bay of Plenty Regional Council to conduct a monitoring programme to ascertain the effect of these modifications.
Three sites within Lake Rotoehu were sampled monthly at similar depths from October 2014 to May 2015. Sites 1 and 3 were located approximately 30 m from a mixing device and Site 2 acted as a control site as it was considered to be unaffected by the direct effects of the mixing. Zooplankton, phytoplankton and nutrient samples (total nitrogen, total phosphorus, nitrate, ammonium and dissolved phosphorus) were collected at two different depths (0.5 m and 9.0 m), at each site. In addition, CTD (conductivity, temperature, depth) vertical profiles were also taken at each site. Temperature data were also obtained from a fixed-sensor, high-frequency monitoring buoy deployed in the lake and used to determine lake stability.
The summer of 2014-15 produced conditions favourable for the formation of prolonged lake stratification. This resulted in a marked decline in water quality during January-May 2015 in comparison to the previous three years of monitoring data. Evidence of localised homogenisation by the mixing device of the dominant phytoplankton and zooplankton taxonomic groups demonstrated notable improvement in mixing device performance. Temperature profile data were more equivocal, with no clear observations of the effects of artificial mixing over an extended area of the lake. However, supplemental profiles taken from within the discharge plumes (approximately 30 m from the mixing device) demonstrated evidence of hypolimnetic water being discharged to the epilimnion.
It is concluded that the current design and configuration of the artificial mixing devices is effective in drawing water from the hypolimnion into the epilimnion. However, it appears that the thermal mass of Lake Rotoehu is too large for a single mixing device to overcome and there appears to be no substantial ecological benefit in continuing to operate the devices without substantial modification. If significant, sustained improvements in water quality are to be achieved using these devices, further capital investment will be required. Further research investigating the efficiency and area of influence of the mixing devices may help to improve their design and operation.

text: Ecological monitoring of artificial destratification effects in Lake Rotoehu: 2014-2015 Lake Rotoehu is a shallow (mean depth 8 m), polymictic eutrophic lake in the Rotorua lakes district. Catchment land use intensification has contributed to a decline in water quality and persistent cyanobacterial algal blooms for the past 20 years and combines with a background of nutrient-rich geothermal inflows. Two artificial mixing devices were deployed in Lake Rotoehu in the spring of 2012 by the Bay of Plenty Regional Council with the aim of preventing lake thermal stratification. They were previously operated over the summer-autumn periods of 2012-13 and 2013-14 and their effects were monitored on a monthly basis until June 2014. The devices force compressed air through a diffuser near the lake bottom, and into three large vertical cylinders. Buoyancy, caused by the rising bubbles, draws water from the bottom of the lake up through the vertical cylinders and directs it horizontally into the surface mixed layer (epilimnion). This causes mixing of thermally distinct layers of the water column, and is designed to inhibit stratification and prevent hypolimnetic deoxygenation. Results from previous monitoring indicate that the mixing devices produced a limited, localised mixing effect, but had no influence on whole lake ecology. With a view to improving performance, modifications, including channelling all air through a single mixing device and increasing compressor output, were effected in preparation for the 2014-15 summer-autumn seasons. The University of Waikato was contracted by the Bay of Plenty Regional Council to conduct a monitoring programme to ascertain the effect of these modifications.
Three sites within Lake Rotoehu were sampled monthly at similar depths from October 2014 to May 2015. Sites 1 and 3 were located approximately 30 m from a mixing device and Site 2 acted as a control site as it was considered to be unaffected by the direct effects of the mixing. Zooplankton, phytoplankton and nutrient samples (total nitrogen, total phosphorus, nitrate, ammonium and dissolved phosphorus) were collected at two different depths (0.5 m and 9.0 m), at each site. In addition, CTD (conductivity, temperature, depth) vertical profiles were also taken at each site. Temperature data were also obtained from a fixed-sensor, high-frequency monitoring buoy deployed in the lake and used to determine lake stability.
The summer of 2014-15 produced conditions favourable for the formation of prolonged lake stratification. This resulted in a marked decline in water quality during January-May 2015 in comparison to the previous three years of monitoring data. Evidence of localised homogenisation by the mixing device of the dominant phytoplankton and zooplankton taxonomic groups demonstrated notable improvement in mixing device performance. Temperature profile data were more equivocal, with no clear observations of the effects of artificial mixing over an extended area of the lake. However, supplemental profiles taken from within the discharge plumes (approximately 30 m from the mixing device) demonstrated evidence of hypolimnetic water being discharged to the epilimnion.
It is concluded that the current design and configuration of the artificial mixing devices is effective in drawing water from the hypolimnion into the epilimnion. However, it appears that the thermal mass of Lake Rotoehu is too large for a single mixing device to overcome and there appears to be no substantial ecological benefit in continuing to operate the devices without substantial modification. If significant, sustained improvements in water quality are to be achieved using these devices, further capital investment will be required. Further research investigating the efficiency and area of influence of the mixing devices may help to improve their design and operation.

year: 2015

title: Book review: The adventure of the real: Jean Rouch and the craft of ethnographic cinema

authors: Nannicelli, Theodore

abstract: This article reviews the book: “The adventure of the real: Jean Rouch and the craft of ethnographic cinema” by Paul Henley.

text: Book review: The adventure of the real: Jean Rouch and the craft of ethnographic cinema This article reviews the book: “The adventure of the real: Jean Rouch and the craft of ethnographic cinema” by Paul Henley.

year: 2012

title: Engaging the parent/whānau community: Methods, benefits, and challenges for senior leaders in small town and rural New Zealand secondary schools

authors: Kallahar, David

abstract: Engaging parents and whānau (family) in a respectful partnership that develops strong home-school connections and uses effective methods of engagement has the potential to positively affect student outcomes. However, there are also methods of engagement that can be counterproductive and negatively affect student outcomes. This study presents how senior leaders in small town and rural secondary schools in New Zealand are engaging with their parent and whānau community. The investigation reveals what methods they are using to engage parents and whānau and, how effective they and a small number of parents and whānau consider these are, then outlines some of the benefits and challenges that they face in this process. 
The literature reviewed for this study emphasised the benefits of engagement between parents, whānau and school leaders, along with the essential ingredients necessary for successful home-school partnerships and how senior leaders play a critical role in developing the conditions for schools’ engagement with their parent and whānau community. The consideration of aspects from New Zealand’s political and educational history illuminated possible reasons why parents and whānau of Māori descent struggle to connect with schools, and how concepts which have traditionally guided the way of life for these indigenous people can be and are being used by school leaders to develop strong, respectful enduring partnerships. Research on the rural context and how schools in this type of location manage engagement was also studied and seen as yet another factor that senior leaders need to bear in mind when planning for engagement. Examination of three types of engagement – involvement, empowerment, and solidarity, revealed that each is characterised by certain practices and represent a progression in the level of contribution and commitment parents and whānau give to the school. Engagement and progression are, however, dependent on how connected parents and whānau are to their child’s school and how much of a sense of belonging they have.
The study was conducted using an interpretive paradigm to afford richer more detailed descriptions to be gathered from both the senior leaders at three small town and rural schools, and some of the parent and whānau community of each of these schools. A mixed-methods approach was taken to gather and triangulate both qualitative and quantitative data. Qualitative data collected and analysed included semi-structured interviews with senior leaders, descriptive survey submissions from parents and whānau, along with planning and review documents for each school. Quantitative data derived from parents and whānau surveys and represents their preferred methods of engagement with the school statistically.
The study findings indicate that the schools use a range of methods to engage parents and whānau. These include face to face interactions and time-efficient digital communication systems. Some such as an open door policy and parent conferences were reported as effective by leaders and whānau. Furthermore, it was found that there is no one way to engage with all parents and whānau, some liked to participate in events and activities and derived a sense of belonging from this while others simply preferred to gather information and not engage with the school beyond this need. 
Partnerships between parents, whānau and school leaders that were built on respectful relationships and the acknowledgement of difference were said to lead to stronger connections and more productive working relationships, by the senior leaders in all of the schools in the study. These could be said to reflect the use of guiding concepts for living in partnership used by Māori, which the schools in this study were using as foundations in building and sustaining the partnerships with their parents and whānau. The three types of engagement, structured in a progressive framework, also illustrated to school leaders where their parent and whānau community were situated and where they as leaders needed to work further to strengthen and secure both the partnership and to increase engagement.   
Further research as a result of this study could relate to gaining a better understanding of why specific methods of engagement are more acceptable to parents and whānau than others. It could involve looking at the delivery of these methods by senior leaders in more detail, and trialling the three-stage framework on a larger scale and in different contexts, particularly in urban areas where school roll numbers are higher, and communities are less connected.

text: Engaging the parent/whānau community: Methods, benefits, and challenges for senior leaders in small town and rural New Zealand secondary schools Engaging parents and whānau (family) in a respectful partnership that develops strong home-school connections and uses effective methods of engagement has the potential to positively affect student outcomes. However, there are also methods of engagement that can be counterproductive and negatively affect student outcomes. This study presents how senior leaders in small town and rural secondary schools in New Zealand are engaging with their parent and whānau community. The investigation reveals what methods they are using to engage parents and whānau and, how effective they and a small number of parents and whānau consider these are, then outlines some of the benefits and challenges that they face in this process. 
The literature reviewed for this study emphasised the benefits of engagement between parents, whānau and school leaders, along with the essential ingredients necessary for successful home-school partnerships and how senior leaders play a critical role in developing the conditions for schools’ engagement with their parent and whānau community. The consideration of aspects from New Zealand’s political and educational history illuminated possible reasons why parents and whānau of Māori descent struggle to connect with schools, and how concepts which have traditionally guided the way of life for these indigenous people can be and are being used by school leaders to develop strong, respectful enduring partnerships. Research on the rural context and how schools in this type of location manage engagement was also studied and seen as yet another factor that senior leaders need to bear in mind when planning for engagement. Examination of three types of engagement – involvement, empowerment, and solidarity, revealed that each is characterised by certain practices and represent a progression in the level of contribution and commitment parents and whānau give to the school. Engagement and progression are, however, dependent on how connected parents and whānau are to their child’s school and how much of a sense of belonging they have.
The study was conducted using an interpretive paradigm to afford richer more detailed descriptions to be gathered from both the senior leaders at three small town and rural schools, and some of the parent and whānau community of each of these schools. A mixed-methods approach was taken to gather and triangulate both qualitative and quantitative data. Qualitative data collected and analysed included semi-structured interviews with senior leaders, descriptive survey submissions from parents and whānau, along with planning and review documents for each school. Quantitative data derived from parents and whānau surveys and represents their preferred methods of engagement with the school statistically.
The study findings indicate that the schools use a range of methods to engage parents and whānau. These include face to face interactions and time-efficient digital communication systems. Some such as an open door policy and parent conferences were reported as effective by leaders and whānau. Furthermore, it was found that there is no one way to engage with all parents and whānau, some liked to participate in events and activities and derived a sense of belonging from this while others simply preferred to gather information and not engage with the school beyond this need. 
Partnerships between parents, whānau and school leaders that were built on respectful relationships and the acknowledgement of difference were said to lead to stronger connections and more productive working relationships, by the senior leaders in all of the schools in the study. These could be said to reflect the use of guiding concepts for living in partnership used by Māori, which the schools in this study were using as foundations in building and sustaining the partnerships with their parents and whānau. The three types of engagement, structured in a progressive framework, also illustrated to school leaders where their parent and whānau community were situated and where they as leaders needed to work further to strengthen and secure both the partnership and to increase engagement.   
Further research as a result of this study could relate to gaining a better understanding of why specific methods of engagement are more acceptable to parents and whānau than others. It could involve looking at the delivery of these methods by senior leaders in more detail, and trialling the three-stage framework on a larger scale and in different contexts, particularly in urban areas where school roll numbers are higher, and communities are less connected.

year: 2020