title: Phytoplankton dynamics in Lake Tarawera

authors: Baldwin, Amanda Brigitte

subjects: Tarawera

abstract: This study examined the dynamics of phytoplankton populations in deep (maximum depth 84 m), monomictic, oligotrophic Lake Tarawera in the Rotorua lakes district of New Zealand.  Specifically, components of the annual phytoplankton assemblage; a summer deep chlorophyll maximum, a winter areal phytoplankton maximum and nitrogen fixation in ephemeral cyanobacterial surface blooms, are investigated.

Alternate hypotheses for the formation of the observed diatom deep chlorophyll maximum (DCM) in Lake Tarawera were tested.  (1) That growth rates of phytoplankton are higher in the metalimnion than in the epilimnion, perhaps supported by higher concentrations of nutrients in the metalimnion. (2) That the DCM is formed by phytoplankton becoming entrained in more turbulent water at the thermocline and persists while the depth of the thermocline remains above the euphotic depth. 

Lake water concentrations of total inorganic nitrogen and total phosphorus measured monthly over a year at 10 m depth intervals at a mid lake station, provided no evidence that the metalimnion had higher nutrient concentrations than those in the epilimnion.  The productivity of DCM phytoplankton and epilimnion phytoplankton (5 m) was measured c. monthly over the six months that the DCM was present with in situ 13C uptake incubations.  Productivity was consistently higher in 5 m incubations (c. 5  g C L-1 h-1) than in DCM incubations.  The growth of DCM phytoplankton did not appear to be limited by either nitrogen or phosphorus as in situ incubations, over four days, with single or combined additions of these nutrients did not significantly increase chlorophyll a concentrations.  The depth of the DCM was similar to the depth of the thermocline while the thermocline remained above the euphotic depth, but this relationship ceased as the thermocline deepened in autumn and a DCM was no longer discernable.  Light availability at the thermocline therefore appears to be a key factor in regulating the position and persistence of DCM phytoplankton.  Though other studies have demonstrated higher growth of DCM phytoplankton, these maybe incidental, as all DCM formed by negatively buoyant phytoplankton appear to coincide with the depth of the thermocline.

The seasonal areal maximum of chlorophyll a phytoplankton biomass occurred in winter in Lake Tarawera, following the onset of whole lake mixing. This increase was preceded by high (32  g C L-1 h-1) carbon uptakes in in situ 13C surface incubations and increase in total phosphorus concentrations in surface waters.  Lake mixing may redistribute nutrients throughout the water column, and may also alleviate light limitation.  This is because the euphotic depth (25 - 30 m) is approximately half the average lake depth (55 m), so during lake mixing phytoplankton cells are in the euphotic zone half of the time.  The simultaneous increase in nutrients and light is likely to support the observed higher phytoplankton productivity and biomass in winter. 
Though Lake Tarawera is oligotrophic, surface blooms of cyanobacteria, occur from time to time.  In situ incubations of phytoplankton with excess nutrients added, showed that nitrogen was the nutrient most limiting to phytoplankton growth, and ratios of TN:TP from lake water samples also indicated that nitrogen was more likely to be limiting than phosphorus.  Acetylene reduction assays, carried out, in situ, during three shoreline bloom events over a two year period confirmed the presence of nitrogen fixation.  Nitrogen fixation followed a daily pattern, with highest rates of 40 nmol (106 heterocysts) -1 hr-1 at midday.  Though ratios of TN:TP in surface water samples were lowest during winter mixing, surface blooms were only identified in late autumn, toward the end of the stratified period.  Some of the highest concentrations of inorganic nitrogen in surface waters coincided with the occurrence of nitrogen fixation and may have been a consequence of nitrogen leaking from heterocysts.  The overall contribution nitrogen fixation to the lake nutrient budget is highly uncertain, but preliminary estimates attribute between 0.04% and 8% of 'new' nitrogen inputs to nitrogen fixation in Lake Tarawera.

text: Phytoplankton dynamics in Lake Tarawera This study examined the dynamics of phytoplankton populations in deep (maximum depth 84 m), monomictic, oligotrophic Lake Tarawera in the Rotorua lakes district of New Zealand.  Specifically, components of the annual phytoplankton assemblage; a summer deep chlorophyll maximum, a winter areal phytoplankton maximum and nitrogen fixation in ephemeral cyanobacterial surface blooms, are investigated.

Alternate hypotheses for the formation of the observed diatom deep chlorophyll maximum (DCM) in Lake Tarawera were tested.  (1) That growth rates of phytoplankton are higher in the metalimnion than in the epilimnion, perhaps supported by higher concentrations of nutrients in the metalimnion. (2) That the DCM is formed by phytoplankton becoming entrained in more turbulent water at the thermocline and persists while the depth of the thermocline remains above the euphotic depth. 

Lake water concentrations of total inorganic nitrogen and total phosphorus measured monthly over a year at 10 m depth intervals at a mid lake station, provided no evidence that the metalimnion had higher nutrient concentrations than those in the epilimnion.  The productivity of DCM phytoplankton and epilimnion phytoplankton (5 m) was measured c. monthly over the six months that the DCM was present with in situ 13C uptake incubations.  Productivity was consistently higher in 5 m incubations (c. 5  g C L-1 h-1) than in DCM incubations.  The growth of DCM phytoplankton did not appear to be limited by either nitrogen or phosphorus as in situ incubations, over four days, with single or combined additions of these nutrients did not significantly increase chlorophyll a concentrations.  The depth of the DCM was similar to the depth of the thermocline while the thermocline remained above the euphotic depth, but this relationship ceased as the thermocline deepened in autumn and a DCM was no longer discernable.  Light availability at the thermocline therefore appears to be a key factor in regulating the position and persistence of DCM phytoplankton.  Though other studies have demonstrated higher growth of DCM phytoplankton, these maybe incidental, as all DCM formed by negatively buoyant phytoplankton appear to coincide with the depth of the thermocline.

The seasonal areal maximum of chlorophyll a phytoplankton biomass occurred in winter in Lake Tarawera, following the onset of whole lake mixing. This increase was preceded by high (32  g C L-1 h-1) carbon uptakes in in situ 13C surface incubations and increase in total phosphorus concentrations in surface waters.  Lake mixing may redistribute nutrients throughout the water column, and may also alleviate light limitation.  This is because the euphotic depth (25 - 30 m) is approximately half the average lake depth (55 m), so during lake mixing phytoplankton cells are in the euphotic zone half of the time.  The simultaneous increase in nutrients and light is likely to support the observed higher phytoplankton productivity and biomass in winter. 
Though Lake Tarawera is oligotrophic, surface blooms of cyanobacteria, occur from time to time.  In situ incubations of phytoplankton with excess nutrients added, showed that nitrogen was the nutrient most limiting to phytoplankton growth, and ratios of TN:TP from lake water samples also indicated that nitrogen was more likely to be limiting than phosphorus.  Acetylene reduction assays, carried out, in situ, during three shoreline bloom events over a two year period confirmed the presence of nitrogen fixation.  Nitrogen fixation followed a daily pattern, with highest rates of 40 nmol (106 heterocysts) -1 hr-1 at midday.  Though ratios of TN:TP in surface water samples were lowest during winter mixing, surface blooms were only identified in late autumn, toward the end of the stratified period.  Some of the highest concentrations of inorganic nitrogen in surface waters coincided with the occurrence of nitrogen fixation and may have been a consequence of nitrogen leaking from heterocysts.  The overall contribution nitrogen fixation to the lake nutrient budget is highly uncertain, but preliminary estimates attribute between 0.04% and 8% of 'new' nitrogen inputs to nitrogen fixation in Lake Tarawera.

year: 2009

title: How Are Inclusive Education Resource Centre Supported Students With Special Needs Experiencing Education In Regular Classroom Settings In The Town Schools In Western Province Of Papua New Guinea? A Case Study Approach

authors: Bomen, Roweng

abstract: The study considers special needs students’ education development in the context of the Papua New Guinea (PNG) education system. In particular, it examines the experiences, perceptions and expectations of three groups involved, which are teachers, parents and special needs students themselves in relation to inclusive practices in mainstream school settings. While some research has been done in other areas of inclusive education in PNG, none has included the point of view of special needs students attaining education in regular class settings. The study aimed at discovering the extent to which the inclusive education (IE) policy and IE practices are enacted in regular schools in Daru, in PNG. IE practices can be found in schools in PNG, but many are not effective. In particular, we know very little about the special needs students’ experiences, perceptions and expectations of IE in regular class environments, as their voices are not often heard. 

The study undertaken used a qualitative research approach case study to gather data about IE practices in selected schools in Daru Island of Western Province, Papua New Guinea. The research design used was an embedded “single-case” format that strived to explore the reality of the SN students’ experiences in regular classes through talking to them and the adults in their immediate environment. The case study approach used exploratory, descriptive and explanatory methodologies. In the exploratory part, a research framework was set within the context of the research question. In the descriptive part, the research described the concept of inclusive education and its development towards including SN students in PNG society, and in the explanatory part, it focused on the reasons and result of inclusive practices within the context of the children, teachers and adults who care for them. Specifically, interviews were conducted with four teachers, three parents and a focus group consisting of three special needs students. A mini non-participatory class observation was conducted for supplementary information. Data gathered were analysed using a thematic analysis approach.

The findings reveal that special needs students are very interested in attaining education to fulfil their dreams. Their parents’ continuous support towards their SN children’s personal livelihood development was helpful to their SN children. However, a number of social justice issues greatly impacted on how inclusive education for the SN students concerned was being practiced in regular classrooms. Issues included: lack of access to facilities, unbalanced curriculum, teacher-centred teaching rather than SN student-centred teaching and learning practices, limited resources, negative stereotypical behaviour by non-disabled people and social exclusion. This study concludes that more advocacy programmes and a change of people’s mindset towards dealing with SN students in the schools and community are necessary to combat existing discriminatory attitudes and social segregation of special needs students within regular schools and their community.

text: How Are Inclusive Education Resource Centre Supported Students With Special Needs Experiencing Education In Regular Classroom Settings In The Town Schools In Western Province Of Papua New Guinea? A Case Study Approach The study considers special needs students’ education development in the context of the Papua New Guinea (PNG) education system. In particular, it examines the experiences, perceptions and expectations of three groups involved, which are teachers, parents and special needs students themselves in relation to inclusive practices in mainstream school settings. While some research has been done in other areas of inclusive education in PNG, none has included the point of view of special needs students attaining education in regular class settings. The study aimed at discovering the extent to which the inclusive education (IE) policy and IE practices are enacted in regular schools in Daru, in PNG. IE practices can be found in schools in PNG, but many are not effective. In particular, we know very little about the special needs students’ experiences, perceptions and expectations of IE in regular class environments, as their voices are not often heard. 

The study undertaken used a qualitative research approach case study to gather data about IE practices in selected schools in Daru Island of Western Province, Papua New Guinea. The research design used was an embedded “single-case” format that strived to explore the reality of the SN students’ experiences in regular classes through talking to them and the adults in their immediate environment. The case study approach used exploratory, descriptive and explanatory methodologies. In the exploratory part, a research framework was set within the context of the research question. In the descriptive part, the research described the concept of inclusive education and its development towards including SN students in PNG society, and in the explanatory part, it focused on the reasons and result of inclusive practices within the context of the children, teachers and adults who care for them. Specifically, interviews were conducted with four teachers, three parents and a focus group consisting of three special needs students. A mini non-participatory class observation was conducted for supplementary information. Data gathered were analysed using a thematic analysis approach.

The findings reveal that special needs students are very interested in attaining education to fulfil their dreams. Their parents’ continuous support towards their SN children’s personal livelihood development was helpful to their SN children. However, a number of social justice issues greatly impacted on how inclusive education for the SN students concerned was being practiced in regular classrooms. Issues included: lack of access to facilities, unbalanced curriculum, teacher-centred teaching rather than SN student-centred teaching and learning practices, limited resources, negative stereotypical behaviour by non-disabled people and social exclusion. This study concludes that more advocacy programmes and a change of people’s mindset towards dealing with SN students in the schools and community are necessary to combat existing discriminatory attitudes and social segregation of special needs students within regular schools and their community.

year: 2017

title: How Maori have been affected through the notion and practice of schooling: A theoretical analysis

authors: Williamson, Laurie Thomas

abstract: Education has always been associated according to the public with a necessary function to equip individuals to fit into society when they reach adulthood. The fact that it functions with efficiency is attributed in part to the implementation of social norms, which "impose uniformity of behaviour" (Young 2006, p. 1).

This thesis delves into how Maori have been positioned under a mainstream schooling discourse which has put them at a disadvantage since the implementation of a discourse requires the subjugation of those who are not the majority power holders to assimilate into someone else's discourse. The effect of assimilation into a mainstream discourse has political implications for Maori, as schools are the gateway towards social stratification. This thesis will look at the historical and developmental concept of schooling within a western context, moving towards the development of formal schooling in New Zealand and also look at the sociological and political impact of schooling upon Maori students.

I will also differentiate between the terms schooling and education to suggest Maori forms of educational discourse has been marginalised in favour of assimilation into a supposedly equitable rigid, formal system of schooling. I will illustrate the broader concept of education that takes place outside of schools formal boundaries as a way to contrast the level of control and regulation the government initiates within the formal schooling environment. I will also look at the way schools have been used from its colonial beginnings in New Zealand as a way to civilise or impose one cultural practice on another as a way of breaking down uncivilised beliefs and traditions.

text: How Maori have been affected through the notion and practice of schooling: A theoretical analysis Education has always been associated according to the public with a necessary function to equip individuals to fit into society when they reach adulthood. The fact that it functions with efficiency is attributed in part to the implementation of social norms, which "impose uniformity of behaviour" (Young 2006, p. 1).

This thesis delves into how Maori have been positioned under a mainstream schooling discourse which has put them at a disadvantage since the implementation of a discourse requires the subjugation of those who are not the majority power holders to assimilate into someone else's discourse. The effect of assimilation into a mainstream discourse has political implications for Maori, as schools are the gateway towards social stratification. This thesis will look at the historical and developmental concept of schooling within a western context, moving towards the development of formal schooling in New Zealand and also look at the sociological and political impact of schooling upon Maori students.

I will also differentiate between the terms schooling and education to suggest Maori forms of educational discourse has been marginalised in favour of assimilation into a supposedly equitable rigid, formal system of schooling. I will illustrate the broader concept of education that takes place outside of schools formal boundaries as a way to contrast the level of control and regulation the government initiates within the formal schooling environment. I will also look at the way schools have been used from its colonial beginnings in New Zealand as a way to civilise or impose one cultural practice on another as a way of breaking down uncivilised beliefs and traditions.

year: 2012