title: Microplastics in freshwaters: Comparing effects of particle properties and an invertebrate consumer on microbial communities and ecosystem functions

authors: Kong, ZH

subjects: Chironomid larvae

abstract: The effects of microplastic (MP) accumulation in freshwaters on organisms and ecosystem functions are poorly understood, as are the roles of MP particle properties in regulating these effects. In freshwater microcosms, we quantified variation in microbial communities and ecosystem functions and compared effects of MP concentration (0, 1000, 50000 particles/kgsediment), shape (sphere, fragment, fibre), and polymer (polyethylene, polyethylene terephthalate, polypropylene, polystyrene) with those of a model invertebrate consumer (Chironomus riparius). We detected multiple effects of specific MP properties, especially associated with MP fragments and fibres, and the polymer polypropylene. These effects included increases in microbial abundance, consumer biomass and ecosystem respiration, as well as decreases in microbial enzyme activity and water chlorophyll-a. MP presence was also associated with increased relative abundance of microbial taxa reported to degrade plastics. However, consumer presence mostly had stronger effects (effect sizes ranging from ± 11 −313 %) than MP exposure (effect sizes ranging from ± 1–89 %) on microbial communities and ecosystem functions. Furthermore, several MP effects were only detected when chironomid consumers were absent. Overall, our findings suggest that MP effects on microbes and ecosystem functions are often relatively small and variable, depending on particle properties and consumer presence. Nevertheless, the number of MP effects detected highlights the need for further investigations of interactions between MPs and other environmental drivers, to more thoroughly assess the risks of MP pollution for freshwater ecosystems.

text: Microplastics in freshwaters: Comparing effects of particle properties and an invertebrate consumer on microbial communities and ecosystem functions The effects of microplastic (MP) accumulation in freshwaters on organisms and ecosystem functions are poorly understood, as are the roles of MP particle properties in regulating these effects. In freshwater microcosms, we quantified variation in microbial communities and ecosystem functions and compared effects of MP concentration (0, 1000, 50000 particles/kgsediment), shape (sphere, fragment, fibre), and polymer (polyethylene, polyethylene terephthalate, polypropylene, polystyrene) with those of a model invertebrate consumer (Chironomus riparius). We detected multiple effects of specific MP properties, especially associated with MP fragments and fibres, and the polymer polypropylene. These effects included increases in microbial abundance, consumer biomass and ecosystem respiration, as well as decreases in microbial enzyme activity and water chlorophyll-a. MP presence was also associated with increased relative abundance of microbial taxa reported to degrade plastics. However, consumer presence mostly had stronger effects (effect sizes ranging from ± 11 −313 %) than MP exposure (effect sizes ranging from ± 1–89 %) on microbial communities and ecosystem functions. Furthermore, several MP effects were only detected when chironomid consumers were absent. Overall, our findings suggest that MP effects on microbes and ecosystem functions are often relatively small and variable, depending on particle properties and consumer presence. Nevertheless, the number of MP effects detected highlights the need for further investigations of interactions between MPs and other environmental drivers, to more thoroughly assess the risks of MP pollution for freshwater ecosystems.

year: 2025

title: Characterisation of bacterioplankton communities in the meltwater ponds of Bratina Island, Victoria Land, Antarctica

authors: Archer, Stephen David James

subjects: Antarctic

abstract: A unique collection of Antarctic aquatic environments (meltwater ponds) lies in close proximity on the rock and sediment-covered undulating surface of the McMurdo Ice Shelf, near Bratina Island (Victoria Land, Antarctica). During the 2009–10 mid-austral summer, sets of discrete water samples were collected across the vertical geochemical gradients of five meltwater ponds (Egg, P70E, Legin, Salt and Orange) for geochemical and microbial community structure analysis. Bacterial DNA fingerprints (using Automated Ribosomal Intergenic Spacer Analysis) statistically clustered communities within ponds based on ANOSIM (R = 0.766, P = 0.001); however, one highly stratified pond (Egg) had two distinct depth-related bacterial communities (R = 0.975, P = 0.008). 454 pyrosequencing at three depths within Egg also identified phylum level shifts and increased diversity with depth, Bacteroidetes being the dominant phyla in the surface sample and Proteobacteria being dominant in the bottom two depths. BEST analysis, which attempts to link community structure and the geochemistry of a pond, identified conductivity and pH individually, and to a lesser extent Ag109, NO2 and V51 as dominant influences to the microbial community structure in these ponds. Increasing abundances of major halo-tolerant OTUs across the strong conductivity gradient reinforce it as the primary driver of community structure in this study

text: Characterisation of bacterioplankton communities in the meltwater ponds of Bratina Island, Victoria Land, Antarctica A unique collection of Antarctic aquatic environments (meltwater ponds) lies in close proximity on the rock and sediment-covered undulating surface of the McMurdo Ice Shelf, near Bratina Island (Victoria Land, Antarctica). During the 2009–10 mid-austral summer, sets of discrete water samples were collected across the vertical geochemical gradients of five meltwater ponds (Egg, P70E, Legin, Salt and Orange) for geochemical and microbial community structure analysis. Bacterial DNA fingerprints (using Automated Ribosomal Intergenic Spacer Analysis) statistically clustered communities within ponds based on ANOSIM (R = 0.766, P = 0.001); however, one highly stratified pond (Egg) had two distinct depth-related bacterial communities (R = 0.975, P = 0.008). 454 pyrosequencing at three depths within Egg also identified phylum level shifts and increased diversity with depth, Bacteroidetes being the dominant phyla in the surface sample and Proteobacteria being dominant in the bottom two depths. BEST analysis, which attempts to link community structure and the geochemistry of a pond, identified conductivity and pH individually, and to a lesser extent Ag109, NO2 and V51 as dominant influences to the microbial community structure in these ponds. Increasing abundances of major halo-tolerant OTUs across the strong conductivity gradient reinforce it as the primary driver of community structure in this study

year: 2014

title: Integrating Maori perspectives into community resilience frameworks for the built environment

authors: Boston, Megan

abstract: Many governments and organisations have attempted to construct frameworks for improving community resilience, particularly as related to the built environment. Many frameworks, globally and locally, take a large overview of society and miss the potential to incorporate cultural, social, and engineering practices followed by indigenous people. However, there is much to learn from the traditional practices of Maori that could directly improve community resilience after a disaster. To date, little research has worked on integrating Maori cultural views into resilience frameworks. Using survey and interview data investigating Maori cultural views on resilience and aspects of the built environment, five Maori values were identified to strengthen resilience. These values are matauranga (knowledge), kotahitanga (unity), kaitiakitanga (guardianship), whakawhanaungatanga (relationships), and manakitanga (extending love). Further, communities can increase community cohesion and unity through adapting building and community layouts learned from observing traditional Maori practices, such as a central marae.

text: Integrating Maori perspectives into community resilience frameworks for the built environment Many governments and organisations have attempted to construct frameworks for improving community resilience, particularly as related to the built environment. Many frameworks, globally and locally, take a large overview of society and miss the potential to incorporate cultural, social, and engineering practices followed by indigenous people. However, there is much to learn from the traditional practices of Maori that could directly improve community resilience after a disaster. To date, little research has worked on integrating Maori cultural views into resilience frameworks. Using survey and interview data investigating Maori cultural views on resilience and aspects of the built environment, five Maori values were identified to strengthen resilience. These values are matauranga (knowledge), kotahitanga (unity), kaitiakitanga (guardianship), whakawhanaungatanga (relationships), and manakitanga (extending love). Further, communities can increase community cohesion and unity through adapting building and community layouts learned from observing traditional Maori practices, such as a central marae.

year: 2022