title: Book review: A Statistical Guide for the Ethically Perplexed

authors: Jorgensen, Murray A.

subjects: book review

abstract: This article reviews the book: “A Statistical Guide for the Ethically Perplexed”, by L. Hubert and H. Wainer.

text: Book review: A Statistical Guide for the Ethically Perplexed This article reviews the book: “A Statistical Guide for the Ethically Perplexed”, by L. Hubert and H. Wainer.

year: 2013

title: Filamentous algae as a nutrient scrubber for agricultural drainage treatment

authors: Hariz, Harizah

subjects: Algal turf scrubber

abstract: Filamentous algae nutrient scrubbers (FANS) have potential as a novel on-farm treatment system to remove and recover diffuse nutrients from agricultural drainage water. FANS use attached filamentous algae that grow and assimilate nutrients from the water which are removed when algal biomass is harvested for beneficial use (e.g. biofertilizer, animal feed supplement). This thesis investigated the attachment abilities, growth rates, biomass productivity and nutrient removal rates of four locally isolated filamentous algae species with the potential for use on FANS to bioremediate nutrients in agricultural drainage water.

To date, a standardised method to assess the productivity and nutrient removal of attached filamentous algae and identify target species for FANS cultivation has not been developed. Therefore, a reproducible bioassay was developed to rapidly assess the ability of four filamentous algae species to attach and grow, remove nutrients, and produce harvestable algal biomass using microscale FANS (μFANS) under controlled indoor conditions. This bioassay included the development of a method for rapid seeding by ‘hooking” algal filaments onto the FANS liner to provide initial physical attachment. Within 14 days, a “lawn” of the seeded algae had established and the “hooked” biomass had attached biologically onto the FANS liner. Oedogonium sp. Was identified as the best performing species overall, with the strongest holdfast attachment, high biomass productivity and high nutrient removal rates.

As the growth and bioremediation performance of filamentous algae can vary with seasonal changes in environmental conditions, the performance of four filamentous algae species was assessed under summer and winter ambient outdoor conditions on mesocosm-scale FANS. Oedogonium sp. Had the highest biomass productivity and nitrate removal rates under both seasons, confirming it as the best performing species. In addition, Oedogonium sp. FANS had the lowest contamination in percentage cover of non-target species compared to the other three species under both summer and winter conditions. These results demonstrate that Oedogonium sp. Has a higher tolerance than the other three species to summer and winter ambient temperature and light variation, enabling Oedogonium sp. To maintain dominance on the floway for a longer period. For these reasons, Oedogonium sp. Was identified as a promising target for year-round cultivation on FANS.

FANS operating parameters can strongly influence algal biomass productivity and nutrient removal. Therefore, the effects of the influent flow rate, harvesting frequency and initial standing crop on unialgal Oedogonium sp. FANS biomass productivity and nutrient removal performance were assessed under controlled environmental conditions to remove any variability in performance due to variations in ambient conditions. Results suggested that an initial standing crop of 70-80 g DW m-2, harvesting frequency of four days and influent flow rate of 1 L min-1 (16.7 L min-1 .m width) were optimal for Oedogonium sp. Cultivated on FANS to maximize biomass productivity and nutrient removal under controlled laboratory conditions. These results contribute to understanding the impacts of operating parameters on optimizing unialgal Oedogonium sp. FANS biomass production and nutrient removal performance.

Despite their potential influence on performance, the effects of FANS seeding methods and species composition have received little attention. Therefore, the effects of seeding method (controlled seeding vs. natural establishment) and seeded species composition (single species vs. mixed species algal assemblages) were investigated in FANS treating agricultural drainage on a dairy farm over seven months. FANS seeded using controlled seeding established biomass five times faster (10 days) than FANS left to establish naturally (7 weeks). Overall, the seeding method and species composition of algae seeded on FANS did not significantly affect biomass productivity and nutrient removal performance. However, FANS seeded with a single species (Oedogonium sp.) had a lower contamination rate in terms of percentage coverage of non-target species than FANS seeded with a mixed species assemblage. These results demonstrate that controlled seeding and cultivation of a single target filamentous algae species can help to maintain a higher abundance of a target species on FANS over a longer period of time, enabling the recovery of high-quality biomass with low variation in algae species composition.

This thesis has demonstrated that FANS can be successfully used to treat nutrients in agricultural drainage water, and therefore could be implemented as a novel tool to assist in mitigating diffuse pollution in New Zealand. The findings can be used to provide farmers and land managers with a clearer understanding of how FANS can be used to remove nutrients from agricultural drainage water to meet water quality objectives while minimizing the impacts on farming activities.

text: Filamentous algae as a nutrient scrubber for agricultural drainage treatment Filamentous algae nutrient scrubbers (FANS) have potential as a novel on-farm treatment system to remove and recover diffuse nutrients from agricultural drainage water. FANS use attached filamentous algae that grow and assimilate nutrients from the water which are removed when algal biomass is harvested for beneficial use (e.g. biofertilizer, animal feed supplement). This thesis investigated the attachment abilities, growth rates, biomass productivity and nutrient removal rates of four locally isolated filamentous algae species with the potential for use on FANS to bioremediate nutrients in agricultural drainage water.

To date, a standardised method to assess the productivity and nutrient removal of attached filamentous algae and identify target species for FANS cultivation has not been developed. Therefore, a reproducible bioassay was developed to rapidly assess the ability of four filamentous algae species to attach and grow, remove nutrients, and produce harvestable algal biomass using microscale FANS (μFANS) under controlled indoor conditions. This bioassay included the development of a method for rapid seeding by ‘hooking” algal filaments onto the FANS liner to provide initial physical attachment. Within 14 days, a “lawn” of the seeded algae had established and the “hooked” biomass had attached biologically onto the FANS liner. Oedogonium sp. Was identified as the best performing species overall, with the strongest holdfast attachment, high biomass productivity and high nutrient removal rates.

As the growth and bioremediation performance of filamentous algae can vary with seasonal changes in environmental conditions, the performance of four filamentous algae species was assessed under summer and winter ambient outdoor conditions on mesocosm-scale FANS. Oedogonium sp. Had the highest biomass productivity and nitrate removal rates under both seasons, confirming it as the best performing species. In addition, Oedogonium sp. FANS had the lowest contamination in percentage cover of non-target species compared to the other three species under both summer and winter conditions. These results demonstrate that Oedogonium sp. Has a higher tolerance than the other three species to summer and winter ambient temperature and light variation, enabling Oedogonium sp. To maintain dominance on the floway for a longer period. For these reasons, Oedogonium sp. Was identified as a promising target for year-round cultivation on FANS.

FANS operating parameters can strongly influence algal biomass productivity and nutrient removal. Therefore, the effects of the influent flow rate, harvesting frequency and initial standing crop on unialgal Oedogonium sp. FANS biomass productivity and nutrient removal performance were assessed under controlled environmental conditions to remove any variability in performance due to variations in ambient conditions. Results suggested that an initial standing crop of 70-80 g DW m-2, harvesting frequency of four days and influent flow rate of 1 L min-1 (16.7 L min-1 .m width) were optimal for Oedogonium sp. Cultivated on FANS to maximize biomass productivity and nutrient removal under controlled laboratory conditions. These results contribute to understanding the impacts of operating parameters on optimizing unialgal Oedogonium sp. FANS biomass production and nutrient removal performance.

Despite their potential influence on performance, the effects of FANS seeding methods and species composition have received little attention. Therefore, the effects of seeding method (controlled seeding vs. natural establishment) and seeded species composition (single species vs. mixed species algal assemblages) were investigated in FANS treating agricultural drainage on a dairy farm over seven months. FANS seeded using controlled seeding established biomass five times faster (10 days) than FANS left to establish naturally (7 weeks). Overall, the seeding method and species composition of algae seeded on FANS did not significantly affect biomass productivity and nutrient removal performance. However, FANS seeded with a single species (Oedogonium sp.) had a lower contamination rate in terms of percentage coverage of non-target species than FANS seeded with a mixed species assemblage. These results demonstrate that controlled seeding and cultivation of a single target filamentous algae species can help to maintain a higher abundance of a target species on FANS over a longer period of time, enabling the recovery of high-quality biomass with low variation in algae species composition.

This thesis has demonstrated that FANS can be successfully used to treat nutrients in agricultural drainage water, and therefore could be implemented as a novel tool to assist in mitigating diffuse pollution in New Zealand. The findings can be used to provide farmers and land managers with a clearer understanding of how FANS can be used to remove nutrients from agricultural drainage water to meet water quality objectives while minimizing the impacts on farming activities.

year: 2023

title: Studies on Paphies australis (Mesodesmatidae) in Whangārei, Aotearoa New Zealand: an investigation into their declining health.

authors: Howells, Joanne Elizabeth

abstract: Disease outbreaks in marine species can have devastating consequences, including increasing host mortality, destabilising commercial production, altering ecosystem functioning, and jeopardising human health. A changing ocean climate is expected to increase host stress and the risk of disease outbreaks. Particularly through new and emerging diseases and opportunistic infections.
Wild bivalve molluscs provide economic, ecological, and socio-cultural benefits. Healthy and sustainable kaimoana (shellfish/bivalves, seafood) are intrinsically linked to the wellbeing of many communities in New Zealand. Over the past decade there has been a noticeable decline in the general health of native marine bivalves, characterised by an increase in observation of mass die-offs. Reasons for this are not clear and could be due to a number of factors, such as sedimentation, harvesting pressures, or disease. Baseline health data on wild bivalve populations are very rare and therefore it is very difficult to identify the causation of ill health. There is a need to establish health baselines to help benchmark changes in infection prevalence and intensity and identify drivers of bivalve mortality events.
Wild bivalve populations are often located in remote and isolated parts of New Zealand. When a mortality event occurs, the logistics of obtaining quality samples for accurate diagnosis can be hindered due to time delays and sample degradation. To gain a better understanding of these limitations for diagnostics using bacteriology, in Chapter 2 I investigate typical sample collection methods (i.e., samples collected and sent to a testing laboratory) and sample collections immediately in the field to understand what effect different sample methods have on number and types of bacteria isolated. Although the results of Chapter 2 found there were limitations to both sampling methods, it did identify that typical sampling techniques were not wholly optimal, and the information gained by sampling immediately in the field retained additional information that could be essential for disease diagnostics. Field sampling for bacteriology was applied throughout this thesis research.
Pipi (Paphies australis) are native bivalves to New Zealand, inhabiting the shallow subtidal of estuaries and bays. Pipi have suffered serious population declines in an area of northern New Zealand (Whangārei) since 2009. I investigate possible drivers of the poor health of pipi in Whangārei, with the objective of identifying the mechanisms that have contributed to the decline, and prevention of the recovery of pipi in Whangārei, with a primary focus of disease as a causative agent. I establish a health baseline of pipi from Whangārei using histopathology, bacteriology, and qPCR of Endozoicomonas spp., a bacteria previously identified in mortality bivalves (Chapter 3). The health baseline was compared against samples collected during three mass mortality events to help identify drivers of mass mortality events (Chapter 4). Through laboratory experimentation, I test whether pipi exposed to stressors had higher infection intensity and prevalence of Endozoicomonas spp. (Chapter 5). Finally, using archived samples, I test whether the baseline data established was consistent through time and help to provide insights into considerations when analysing bivalve mass mortality events (Chapter 6).
I found that Endozoicomonas spp. make an important part of pipi host microbiome. Although Endozoicomonas spp. are highly prevalent in pipi collected during a mass mortality event, their infection intensity was significantly lower in moribund pipi than healthy pipi. The prevalence and infection intensity of Endozoicomonas spp. were not driven by environmental stressors. The stressors, however, did appear to impact host health, with high suspended sediment loads and water temperatures of 24°C appeared to be unfavourable to pipi. Overall, Endozoicomonas sp. does not appear to be a main driver in the declining population of pipi from Whangārei and is probably not important to bivalve health. The reduced prevalence and infection intensity of Endozoicomonas sp. in healthy pipi strongly suggests these bacteria are symbiotic. A relationship that has been reported for this bacterial group in species of coral and sponges.
The establishment of a health baseline represents a significant step forward towards biosecurity preparedness by being able to identify changes in infection prevalence and intensity against it. The operational use of these data when paired with historical data will be a powerful tool to identify patterns of disease dynamics and emerging disease.

text: Studies on Paphies australis (Mesodesmatidae) in Whangārei, Aotearoa New Zealand: an investigation into their declining health. Disease outbreaks in marine species can have devastating consequences, including increasing host mortality, destabilising commercial production, altering ecosystem functioning, and jeopardising human health. A changing ocean climate is expected to increase host stress and the risk of disease outbreaks. Particularly through new and emerging diseases and opportunistic infections.
Wild bivalve molluscs provide economic, ecological, and socio-cultural benefits. Healthy and sustainable kaimoana (shellfish/bivalves, seafood) are intrinsically linked to the wellbeing of many communities in New Zealand. Over the past decade there has been a noticeable decline in the general health of native marine bivalves, characterised by an increase in observation of mass die-offs. Reasons for this are not clear and could be due to a number of factors, such as sedimentation, harvesting pressures, or disease. Baseline health data on wild bivalve populations are very rare and therefore it is very difficult to identify the causation of ill health. There is a need to establish health baselines to help benchmark changes in infection prevalence and intensity and identify drivers of bivalve mortality events.
Wild bivalve populations are often located in remote and isolated parts of New Zealand. When a mortality event occurs, the logistics of obtaining quality samples for accurate diagnosis can be hindered due to time delays and sample degradation. To gain a better understanding of these limitations for diagnostics using bacteriology, in Chapter 2 I investigate typical sample collection methods (i.e., samples collected and sent to a testing laboratory) and sample collections immediately in the field to understand what effect different sample methods have on number and types of bacteria isolated. Although the results of Chapter 2 found there were limitations to both sampling methods, it did identify that typical sampling techniques were not wholly optimal, and the information gained by sampling immediately in the field retained additional information that could be essential for disease diagnostics. Field sampling for bacteriology was applied throughout this thesis research.
Pipi (Paphies australis) are native bivalves to New Zealand, inhabiting the shallow subtidal of estuaries and bays. Pipi have suffered serious population declines in an area of northern New Zealand (Whangārei) since 2009. I investigate possible drivers of the poor health of pipi in Whangārei, with the objective of identifying the mechanisms that have contributed to the decline, and prevention of the recovery of pipi in Whangārei, with a primary focus of disease as a causative agent. I establish a health baseline of pipi from Whangārei using histopathology, bacteriology, and qPCR of Endozoicomonas spp., a bacteria previously identified in mortality bivalves (Chapter 3). The health baseline was compared against samples collected during three mass mortality events to help identify drivers of mass mortality events (Chapter 4). Through laboratory experimentation, I test whether pipi exposed to stressors had higher infection intensity and prevalence of Endozoicomonas spp. (Chapter 5). Finally, using archived samples, I test whether the baseline data established was consistent through time and help to provide insights into considerations when analysing bivalve mass mortality events (Chapter 6).
I found that Endozoicomonas spp. make an important part of pipi host microbiome. Although Endozoicomonas spp. are highly prevalent in pipi collected during a mass mortality event, their infection intensity was significantly lower in moribund pipi than healthy pipi. The prevalence and infection intensity of Endozoicomonas spp. were not driven by environmental stressors. The stressors, however, did appear to impact host health, with high suspended sediment loads and water temperatures of 24°C appeared to be unfavourable to pipi. Overall, Endozoicomonas sp. does not appear to be a main driver in the declining population of pipi from Whangārei and is probably not important to bivalve health. The reduced prevalence and infection intensity of Endozoicomonas sp. in healthy pipi strongly suggests these bacteria are symbiotic. A relationship that has been reported for this bacterial group in species of coral and sponges.
The establishment of a health baseline represents a significant step forward towards biosecurity preparedness by being able to identify changes in infection prevalence and intensity against it. The operational use of these data when paired with historical data will be a powerful tool to identify patterns of disease dynamics and emerging disease.

year: 2023