title: In-situ fluorescence monitoring of cyanobacteria: Laboratory-based quantification of species-specific measurement accuracy.

authors: Bertone, Edoardo

subjects: Cyanobacteria

abstract: In recent years, in-situ fluorometers have been extensively deployed to monitor cyanobacteria in near real-time. Acceptable accuracy can be achieved between measured pigments and cyanobacteria biovolume provided the cyanobacteria species are known. However, cellular photosynthetic pigment content and measurement interferences are site and species specific and can dramatically affect sensor reliability. We quantified the accuracy of an in-situ fluorometer compared with traditional methods using mono- and mixed cultures of four different cyanobacterial species. We found: (1) lower pigment content in cultures in stationary phase, (2) higher precision with the sensor compared to traditional pigment quantification methods of measuring phycocyanin and chlorophyll a, (3) species-specific relationships between sensor readings and measurements related to biovolume, (4) overestimation of pigments in mixed compared with mono cultures, (5) dissolved organic matter causing a loss in signal proportional to its degree of aromaticity, and (6) potential to quantify the degree of cell lysis with a fluorescent dissolved organic matter sensor. This study has provided important new information on the strengths and limitations of fluorescence sensors. The sensor readings can provide accurate biovolume quantification and species determination for a number of bloom-forming species when sensors are properly compensated and calibrated.

text: In-situ fluorescence monitoring of cyanobacteria: Laboratory-based quantification of species-specific measurement accuracy. In recent years, in-situ fluorometers have been extensively deployed to monitor cyanobacteria in near real-time. Acceptable accuracy can be achieved between measured pigments and cyanobacteria biovolume provided the cyanobacteria species are known. However, cellular photosynthetic pigment content and measurement interferences are site and species specific and can dramatically affect sensor reliability. We quantified the accuracy of an in-situ fluorometer compared with traditional methods using mono- and mixed cultures of four different cyanobacterial species. We found: (1) lower pigment content in cultures in stationary phase, (2) higher precision with the sensor compared to traditional pigment quantification methods of measuring phycocyanin and chlorophyll a, (3) species-specific relationships between sensor readings and measurements related to biovolume, (4) overestimation of pigments in mixed compared with mono cultures, (5) dissolved organic matter causing a loss in signal proportional to its degree of aromaticity, and (6) potential to quantify the degree of cell lysis with a fluorescent dissolved organic matter sensor. This study has provided important new information on the strengths and limitations of fluorescence sensors. The sensor readings can provide accurate biovolume quantification and species determination for a number of bloom-forming species when sensors are properly compensated and calibrated.

year: 2019

title: Fish and macroinvertebrates in lowland drainage canals with and without grass carp

authors: Hicks, Brendan J.

subjects: biology

abstract: Diploid grass carp (Ctenopharyngodon idella
L.) were introduced to a lowland Waikato drainage canal at an initial density of 40-80 kg ha -1(83-167 fish ha -1) to control aquatic macrophytes and improve water flow. A near-by canal was left without grass carp to act as an untreated control. After 7 months, macrophytes occupied 17% of the  water column in the treated canal compared to 78% in the untreated canal. Fish and macroinvertebrates in both canals were examined before and after the release of grass carp by sampling with replacement by fyke netting on seven occasions. Brown bullhead catfish (Ameiurus nebulosus (Lesueur)) and shortfinned eels (Anguilla australis Richardson) comprised most of the
resident fish biomass in both canals;  however, before grass carp stocking, eels were more abundant than catfish in the 
treated canal. There was no change in the abundance of resident fish after stocking, but young-of-the-year catfish had greater mortality and grew faster in the treated canal than in the untreated canal. Macroinvertebrates were primarily associated
with aquatic macrophytes. Grass carp reduced aquatic macrophyte abundance in the treated canal by about 80%, which by inference reduced the abundance of associated macroinvertebrates, but there was no  observed impact of grass carp stocking on the resident fish assemblage. We examined
the relationship between head width and fish length, and from this determined that 70% of the grass carp could have escaped through the downstream retention screen. Despite
this possibility, grass carp remained in the canal and effectively controlled aquatic macrophytes for 18 months.

text: Fish and macroinvertebrates in lowland drainage canals with and without grass carp Diploid grass carp (Ctenopharyngodon idella
L.) were introduced to a lowland Waikato drainage canal at an initial density of 40-80 kg ha -1(83-167 fish ha -1) to control aquatic macrophytes and improve water flow. A near-by canal was left without grass carp to act as an untreated control. After 7 months, macrophytes occupied 17% of the  water column in the treated canal compared to 78% in the untreated canal. Fish and macroinvertebrates in both canals were examined before and after the release of grass carp by sampling with replacement by fyke netting on seven occasions. Brown bullhead catfish (Ameiurus nebulosus (Lesueur)) and shortfinned eels (Anguilla australis Richardson) comprised most of the
resident fish biomass in both canals;  however, before grass carp stocking, eels were more abundant than catfish in the 
treated canal. There was no change in the abundance of resident fish after stocking, but young-of-the-year catfish had greater mortality and grew faster in the treated canal than in the untreated canal. Macroinvertebrates were primarily associated
with aquatic macrophytes. Grass carp reduced aquatic macrophyte abundance in the treated canal by about 80%, which by inference reduced the abundance of associated macroinvertebrates, but there was no  observed impact of grass carp stocking on the resident fish assemblage. We examined
the relationship between head width and fish length, and from this determined that 70% of the grass carp could have escaped through the downstream retention screen. Despite
this possibility, grass carp remained in the canal and effectively controlled aquatic macrophytes for 18 months.

year: 2006-07

title: Through the eyes of whānau: Destruction of cultural identity through education

authors: Ngaamo, Raewyn Brenda

subjects: Māori

abstract: This thesis examines how the schooling experiences of a dual cultural heritage whānau influenced the development of their identity, their language and culture across three generations. Koro, Tuakana, Teina and Moko share their experiences with us and through these stories reveal how they were forced through the colonising beliefs and practices of schooling to reshape themselves in a bid to belong. The compromise and abuse of cultural identity in wider society, replicated and validated in schooling, created a vicious and dehumanising experience for each of them. School was a major site of assimilation for this whānau. They experienced racism, rejection, low expectations and cultural disconnection across the three generations. They suffered particularly as dual heritage children who experienced rejection and racial micro aggressions from both Pākehā and Māori alike. Instead of education being a means to realise their potential and to achieve success it was actually the vehicle for the destruction of their cultural identity.

text: Through the eyes of whānau: Destruction of cultural identity through education This thesis examines how the schooling experiences of a dual cultural heritage whānau influenced the development of their identity, their language and culture across three generations. Koro, Tuakana, Teina and Moko share their experiences with us and through these stories reveal how they were forced through the colonising beliefs and practices of schooling to reshape themselves in a bid to belong. The compromise and abuse of cultural identity in wider society, replicated and validated in schooling, created a vicious and dehumanising experience for each of them. School was a major site of assimilation for this whānau. They experienced racism, rejection, low expectations and cultural disconnection across the three generations. They suffered particularly as dual heritage children who experienced rejection and racial micro aggressions from both Pākehā and Māori alike. Instead of education being a means to realise their potential and to achieve success it was actually the vehicle for the destruction of their cultural identity.

year: 2019