title: Ecology of aquatic hyphomycetes in New Zealand streams

authors: Aimer, Robyn Denise

abstract: This work investigated the occurrence of aquatic hyphomycetes in stream ecosystems in New Zealand. It provided evidence for the potential importance of detrital cycles in such ecosystems and of the role of aquatic hyphomycetes in the decay of leaf litter. Leaves from a representative range of plant species were enclosed in mesh bags in two undisturbed streams flowing through different forest types at different altitudes, and fungal population dynamics followed during leaf decay. A method was developed, using pure cultures of appropriate aquatic hyphomycetes, which enabled the mycelial content of leaf material (m mycelium/g) attributable to individual fungal species to be quickly and easily determined from the spore production measured from leaf samples. Antibiotics were used to quantify the relative fungal and bacterial contributions to microbial activity of leaf samples through the selective inhibition of respiration. Fungi accounted for about half of the total microbial respiration, and on average 80 % of this fungal respiration was attributable to aquatic hyphomycetes.

Three major patterns were apparent from the data for aquatic hyphomycete population dynamics. 1) A successional pattern was identified among aquatic hyphomycetes, with the species falling into three groups on the basis of the order of their period of abundance. 2) Aquatic hyphomycete abundance varied among leaf types, with soft-rotting types (hangehange, young kanono) being poorly colonised compared to firmer, darker-rotting types (old kanono, kamahi, silver beech, tawa, kauri, and rimu). Nikau (palm) and ponga (fern) leaves, although not soft-rotting, were also poorly colonised by aquatic hyphomycetes, but bore a rich alternative mycoflora. 3) The occurrence of many aquatic hyphomycetes showed seasonal preferences and a distinct geographical distribution which followed that of higher plants. Both seasonal and geographical patterns were probably related to temperature.

Laboratory evidence was obtained of the potential importance of oxygen in determining aquatic hyphomycete occurrence, with the dominant species in most New Zealand streams (Lunulospora cymbiformis) being extremely intolerant of low oxygen conditions. Two new species of aquatic hyphomycetes were isolated in the course of the work.

text: Ecology of aquatic hyphomycetes in New Zealand streams This work investigated the occurrence of aquatic hyphomycetes in stream ecosystems in New Zealand. It provided evidence for the potential importance of detrital cycles in such ecosystems and of the role of aquatic hyphomycetes in the decay of leaf litter. Leaves from a representative range of plant species were enclosed in mesh bags in two undisturbed streams flowing through different forest types at different altitudes, and fungal population dynamics followed during leaf decay. A method was developed, using pure cultures of appropriate aquatic hyphomycetes, which enabled the mycelial content of leaf material (m mycelium/g) attributable to individual fungal species to be quickly and easily determined from the spore production measured from leaf samples. Antibiotics were used to quantify the relative fungal and bacterial contributions to microbial activity of leaf samples through the selective inhibition of respiration. Fungi accounted for about half of the total microbial respiration, and on average 80 % of this fungal respiration was attributable to aquatic hyphomycetes.

Three major patterns were apparent from the data for aquatic hyphomycete population dynamics. 1) A successional pattern was identified among aquatic hyphomycetes, with the species falling into three groups on the basis of the order of their period of abundance. 2) Aquatic hyphomycete abundance varied among leaf types, with soft-rotting types (hangehange, young kanono) being poorly colonised compared to firmer, darker-rotting types (old kanono, kamahi, silver beech, tawa, kauri, and rimu). Nikau (palm) and ponga (fern) leaves, although not soft-rotting, were also poorly colonised by aquatic hyphomycetes, but bore a rich alternative mycoflora. 3) The occurrence of many aquatic hyphomycetes showed seasonal preferences and a distinct geographical distribution which followed that of higher plants. Both seasonal and geographical patterns were probably related to temperature.

Laboratory evidence was obtained of the potential importance of oxygen in determining aquatic hyphomycete occurrence, with the dominant species in most New Zealand streams (Lunulospora cymbiformis) being extremely intolerant of low oxygen conditions. Two new species of aquatic hyphomycetes were isolated in the course of the work.

year: 1989

title: Testing the fundamental assumption of choice experiments: Are values absolute or relative?

authors: Luisetti, Tiziana

subjects: choice experiment

abstract: A split sample experiment is conducted to test one of the most fundamental assumptions underpinning choice experiments in an environmental setting: whether stated values are absolute or relative. The test uses a natural experiment involving respondents at different home locations relative to potential new wetland sites. Respondents were presented with one of two ranges of distances. An absolute value interpretation requires that the functional relations with distance derived from these two ranges be consistent with each other. We reject a null hypothesis of no range bias, suggesting that respondents may perceive attribute levels in a relative rather than absolute sense.

text: Testing the fundamental assumption of choice experiments: Are values absolute or relative? A split sample experiment is conducted to test one of the most fundamental assumptions underpinning choice experiments in an environmental setting: whether stated values are absolute or relative. The test uses a natural experiment involving respondents at different home locations relative to potential new wetland sites. Respondents were presented with one of two ranges of distances. An absolute value interpretation requires that the functional relations with distance derived from these two ranges be consistent with each other. We reject a null hypothesis of no range bias, suggesting that respondents may perceive attribute levels in a relative rather than absolute sense.

year: 2011

title: Too many Māori and Asian people are drowning – can better cultural understanding reverse the trend?

authors: Wheaton, Belinda

abstract: The article discusses the high rate of drownings in New Zealand, particularly among Māori and Asian communities. It highlights the need for culturally specific water safety education to address this issue. The Asian community, in particular, includes many first-generation migrants who may lack water skills due to their upbringing and fear of water. Overprotectiveness towards children around water is also common among Asian parents. The article emphasizes the importance of providing support and learning opportunities to help Asian migrants develop water skills and feel more comfortable in outdoor activities. Additionally, it mentions the declining water skills among New Zealand children in general and the need for better resourcing of school programs and community initiatives like ActivAsian. Culturally relevant knowledge and education are deemed crucial in changing attitudes and behaviors towards water safety. The article stresses that making New Zealand's beaches and waterways safe for all residents, including migrants, requires targeted funding and a collaborative effort to prevent tragic drowning incidents.

text: Too many Māori and Asian people are drowning – can better cultural understanding reverse the trend? The article discusses the high rate of drownings in New Zealand, particularly among Māori and Asian communities. It highlights the need for culturally specific water safety education to address this issue. The Asian community, in particular, includes many first-generation migrants who may lack water skills due to their upbringing and fear of water. Overprotectiveness towards children around water is also common among Asian parents. The article emphasizes the importance of providing support and learning opportunities to help Asian migrants develop water skills and feel more comfortable in outdoor activities. Additionally, it mentions the declining water skills among New Zealand children in general and the need for better resourcing of school programs and community initiatives like ActivAsian. Culturally relevant knowledge and education are deemed crucial in changing attitudes and behaviors towards water safety. The article stresses that making New Zealand's beaches and waterways safe for all residents, including migrants, requires targeted funding and a collaborative effort to prevent tragic drowning incidents.

year: 2022-12-20