title: New Zealand stream crayfish: Functional omnivores but trophic predators?

authors: Parkyn, Stephanie M.

subjects: energy sources

abstract: 1. The feeding ecology of the crayfish Paranephrops planifrons in streams draining catchments in native forest and pastoral land was investigated using analyses of both stomach contents and stable isotopes of carbon and nitrogen. We aimed to (1) identify the energy sources of crayfish, (2) determine whether these were affected by ontogeny or land use change, and (3) assess the functional and trophic roles of crayfish in New Zealand hill-country streams.
2. In native forest streams, crayfish stomach contents were dominated volumetrically by leaf detritus (>60%), but in pasture streams aquatic invertebrates constituted more than 40% of stomach volumes and leaf detritus <30%. Stable isotope analyses revealed that crayfish from both native forest and pasture streams incorporated energy from aquatic invertebrates into their body tissue but did not appear to utilize detritus for growth. Therefore, deforestation had little impact on crayfish energy sources.
3. In native forest streams, adult crayfish (≥20 mm orbit-carapace length (OCL)) consumed greater amounts of leaf detritus than juvenile crayfish, but a corresponding change in stable isotope signatures was not detected. Ontogenetic shifts in diet were not consistent between land use suggesting that change in local habitat and food resources, as a result of land use change, affect crayfish food choice more than factors related solely to age or size.
4. Crayfish appear to occupy the trophic position of a predator, but by functioning as omnivores, they have dual roles as both predators and processors of organic matter. The use of gut content analysis in conjunction with stable isotope analyses revealed that the functional and trophic roles of P. planifrons differed, with implications for the interpretation of diet studies and understanding of the role of omnivores in food webs.

text: New Zealand stream crayfish: Functional omnivores but trophic predators? 1. The feeding ecology of the crayfish Paranephrops planifrons in streams draining catchments in native forest and pastoral land was investigated using analyses of both stomach contents and stable isotopes of carbon and nitrogen. We aimed to (1) identify the energy sources of crayfish, (2) determine whether these were affected by ontogeny or land use change, and (3) assess the functional and trophic roles of crayfish in New Zealand hill-country streams.
2. In native forest streams, crayfish stomach contents were dominated volumetrically by leaf detritus (>60%), but in pasture streams aquatic invertebrates constituted more than 40% of stomach volumes and leaf detritus <30%. Stable isotope analyses revealed that crayfish from both native forest and pasture streams incorporated energy from aquatic invertebrates into their body tissue but did not appear to utilize detritus for growth. Therefore, deforestation had little impact on crayfish energy sources.
3. In native forest streams, adult crayfish (≥20 mm orbit-carapace length (OCL)) consumed greater amounts of leaf detritus than juvenile crayfish, but a corresponding change in stable isotope signatures was not detected. Ontogenetic shifts in diet were not consistent between land use suggesting that change in local habitat and food resources, as a result of land use change, affect crayfish food choice more than factors related solely to age or size.
4. Crayfish appear to occupy the trophic position of a predator, but by functioning as omnivores, they have dual roles as both predators and processors of organic matter. The use of gut content analysis in conjunction with stable isotope analyses revealed that the functional and trophic roles of P. planifrons differed, with implications for the interpretation of diet studies and understanding of the role of omnivores in food webs.

year: 2001

title: Determinants of WTP for Prosecco wine: A latent class regression with attitudinal responses

authors: Thiene, Mara

subjects: Consumer behaviour

abstract: Purpose:Under investigation is Prosecco wine, a sparkling white wine from North-East Italy. Information collection on consumer perceptions is particularly relevant when developing market strategies for wine, especially so when local production and certification of origin play an important role in the wine market of a given district, as in the case at hand. Investigating and characterizing the structure of preference heterogeneity become crucial steps in every successful marketing strategy. The purpose of this paper is to investigate the sources of systematic differences in consumer preferences. 
Design/methodology/approach: The paper explores the effect of inclusion of answers to attitudinal questions in a latent class regression model of stated willingness to pay (WTP) for this specialty wine. These additional variables were included in the membership equations to investigate whether they could be of help in the identification of latent classes. The individual specific WTPs from the sampled respondents were then derived from the best fitting model and examined for consistency. 
Findings: The use of answers to attitudinal question in the latent class regression model is found to improve model fit, thereby helping in the identification of latent classes. The best performing model obtained makes use of both attitudinal scores and socio-economic covariates identifying five latent classes. A reasonable pattern of differences in WTP for Prosecco between CDO and TGI types were derived from this model. 
Originality/value: The approach appears informative and promising: attitudes emerge as important ancillary indicators of taste differences for specialty wines. This might be of interest per se and of practical use in market segmentation. If future research shows that these variables can be of use in other contexts, it is quite possible that more attitudinal questions will be routinely incorporated in structural latent class hedonic models.

text: Determinants of WTP for Prosecco wine: A latent class regression with attitudinal responses Purpose:Under investigation is Prosecco wine, a sparkling white wine from North-East Italy. Information collection on consumer perceptions is particularly relevant when developing market strategies for wine, especially so when local production and certification of origin play an important role in the wine market of a given district, as in the case at hand. Investigating and characterizing the structure of preference heterogeneity become crucial steps in every successful marketing strategy. The purpose of this paper is to investigate the sources of systematic differences in consumer preferences. 
Design/methodology/approach: The paper explores the effect of inclusion of answers to attitudinal questions in a latent class regression model of stated willingness to pay (WTP) for this specialty wine. These additional variables were included in the membership equations to investigate whether they could be of help in the identification of latent classes. The individual specific WTPs from the sampled respondents were then derived from the best fitting model and examined for consistency. 
Findings: The use of answers to attitudinal question in the latent class regression model is found to improve model fit, thereby helping in the identification of latent classes. The best performing model obtained makes use of both attitudinal scores and socio-economic covariates identifying five latent classes. A reasonable pattern of differences in WTP for Prosecco between CDO and TGI types were derived from this model. 
Originality/value: The approach appears informative and promising: attitudes emerge as important ancillary indicators of taste differences for specialty wines. This might be of interest per se and of practical use in market segmentation. If future research shows that these variables can be of use in other contexts, it is quite possible that more attitudinal questions will be routinely incorporated in structural latent class hedonic models.

year: 2013

title: Maori women and dual ethnicity: Non-congruence, “passing” and “real Maori”

authors: Gibson, Kelly

subjects: Maori

abstract: In this study, I wanted to explore the often uncomfortable experience of having dual ethnicity. I did
this through open-ended interviews with nine women, who, like me, were aged between 20 and 30
and who identified as being of both Maori and Pakeha (or other) descent.
While the women all identified as having dual ethnicity, as the interviews progressed it became
clear that many of them had little pride in being of Pakeha descent and identified more strongly
with their Maori heritage. In most instances the way they were identified by other people was
incongruent with how the participants identified themselves. By virtue of having fair skin, many
were able to “pass” as Pakeha. This provided them with certain advantages, notably being exempt
from racist treatment. On the other hand, their appearance often resulted in them being labelled as
not being a “real Maori.” Paradoxically, when they were identified as Maori, others, both Maori
and non-Maori, sometimes expected them to be an expert in all things Maori. For most participants
being a “real” Maori did not rely on looking Maori or on being able to speak Te Reo fluently.
Instead, having whakapapa was considered the most essential element on which to base their Maori
identity.

text: Maori women and dual ethnicity: Non-congruence, “passing” and “real Maori” In this study, I wanted to explore the often uncomfortable experience of having dual ethnicity. I did
this through open-ended interviews with nine women, who, like me, were aged between 20 and 30
and who identified as being of both Maori and Pakeha (or other) descent.
While the women all identified as having dual ethnicity, as the interviews progressed it became
clear that many of them had little pride in being of Pakeha descent and identified more strongly
with their Maori heritage. In most instances the way they were identified by other people was
incongruent with how the participants identified themselves. By virtue of having fair skin, many
were able to “pass” as Pakeha. This provided them with certain advantages, notably being exempt
from racist treatment. On the other hand, their appearance often resulted in them being labelled as
not being a “real Maori.” Paradoxically, when they were identified as Maori, others, both Maori
and non-Maori, sometimes expected them to be an expert in all things Maori. For most participants
being a “real” Maori did not rely on looking Maori or on being able to speak Te Reo fluently.
Instead, having whakapapa was considered the most essential element on which to base their Maori
identity.

year: 1999