title: The impact of macrophyte mats on biodiversity and ecosystem functioning of benthic communities

authors: Niemand, Clarisse

subjects: bivalves

abstract: Macroalgal blooms, such as Ulva spp., are a common disturbance to estuarine benthic fauna worldwide. As large quantities of macroalgae break free from growing substrates, drifting mats are formed that eventually deposit in low energy environments, including intertidal sandflats. The mats will typically settle on the sediment surface as large sheets. Once these sheets start to decompose, detritus is formed, which is eventually incorporated into the benthic food web; however, the ability to process detritus is dependent on the species present. This thesis examined the impacts of Ulva on the benthic macrofaunal communities and ecosystem functions, at different phases of decomposition; firstly, as large sheets (Chapter 2), then as detritus (Chapter 3), and finally as the Ulva detritus is incorporated and reworked into the sediment and foodweb (Chapters 4 and 5). 

The impacts of intact macroalgal mats on the sediment characteristics, community composition and ecosystem functions (i.e. benthic primary production, metabolism, and nutrient cycling) associated with an intertidal macrofaunal community in Tauranga Harbour were measured in a manipulative field experiment. Temporal changes and recovery of the community and the ecosystem functions they provide were measured twice over a 14-day period. Subtle treatment effects were observed in the macrofaunal community and sediment characteristics, which in turn resulted in subtle shifts in chlorophyll a (chl a) corrected gross primary production. However, there were no significant impacts on the key benthic species (the suspension-feeder Austrovenus stutchburyi and the deposit-feeder Macomona liliana) at this site, which is likely the reason more significant treatment effects were not observed in the measures of ecosystem function. Significant temporal variation was measured in most sediment properties (all except for phaeophytin), and also in benthic primary production. This study emphasized the importance of temporal variability when measuring ecosystem functions in shallow intertidal environments.

A second manipulative field experiment examined the impact of different quantities of Ulva detritus (low [60 g dw m-2], medium [120 g dw m-2] and high [240 g dw m-2]) on the sediment properties, benthic community composition and ecosystem functions of an estuarine benthic community. Plots were sampled on three occasions over an 8-week period, to examine changes in macrofauna and/or ecosystem functions over time. The only significant treatment effect was less gross ammonium flux from the sediment in procedural controls compared to low density treatments. Although no further significant treatment effects were detected, important temporal variation was observed. The macrofaunal community varied significantly between all three the sampling dates, while gross primary production, sediment oxygen consumption, and nutrient efflux from the light and dark chambers varied between at least two of the sampling dates. The results from this study again highlighted the important temporal changes that can be observed over relatively short time scales, and the importance of measuring temporal variation, particularly when measuring ecosystem functions such as primary production and benthic metabolism.

Finally, in a laboratory study, I examined the density dependent effects of two key intertidal bivalve species (A. stutchburyi and M. liliana) and their associated communities on the breakdown, loss, burial and uptake of Ulva detritus. Results showed that the site dominated by A. stutchburyi (AS) had higher overall chl a biomass and chl a was distributed evenly throughout the sediment profile, whilst less labelled Ulva was retained in the sediment. Both chl a biomass and the amount of Ulva recovered were correlated with the density of M. liliana, but only in cores collected from AS sites. Cores collected from the M. liliana dominated site (ML) showed an exponential decline in chl a with depth, and chl a biomass was negatively correlated with species richness. In ML cores (which had very low A. stutchburyi abundances), M. liliana densities showed no correlation with chl a biomass or the amount of Ulva that was recovered, which suggested that the community present in cores from AS is important in facilitating the impact by M. liliana on the mixing and the reworking of organic matter. These results emphasize the value of considering whole communities, and not just key species, when trying to understand sediment mixing and organic matter processing.

Although the addition of Ulva did not result in large and obvious shifts in community composition or ecosystem function, small subtle shifts were observed. These results underpinned the complex nature of biotic and abiotic interactions in dynamic systems like estuaries, but show that for the most part, ecosystem functions are robust. Temporal variations in ecosystem functions appeared to be largely driven by environmental conditions such as light availability, and were a more prominent driver in the differences observed in ecosystem function compared to treatment effects of Ulva addition. The results also highlighted the importance of community composition in the processing and reworking of macroalgal detritus, which further emphasized the complexity of estuarine systems. The results from this research suggest that on intertidal sandflats, providing the abundances of key species remain intact, the benthic community composition can shift, and species can be lost, without a significant loss or shift in overall ecosystem function.

text: The impact of macrophyte mats on biodiversity and ecosystem functioning of benthic communities Macroalgal blooms, such as Ulva spp., are a common disturbance to estuarine benthic fauna worldwide. As large quantities of macroalgae break free from growing substrates, drifting mats are formed that eventually deposit in low energy environments, including intertidal sandflats. The mats will typically settle on the sediment surface as large sheets. Once these sheets start to decompose, detritus is formed, which is eventually incorporated into the benthic food web; however, the ability to process detritus is dependent on the species present. This thesis examined the impacts of Ulva on the benthic macrofaunal communities and ecosystem functions, at different phases of decomposition; firstly, as large sheets (Chapter 2), then as detritus (Chapter 3), and finally as the Ulva detritus is incorporated and reworked into the sediment and foodweb (Chapters 4 and 5). 

The impacts of intact macroalgal mats on the sediment characteristics, community composition and ecosystem functions (i.e. benthic primary production, metabolism, and nutrient cycling) associated with an intertidal macrofaunal community in Tauranga Harbour were measured in a manipulative field experiment. Temporal changes and recovery of the community and the ecosystem functions they provide were measured twice over a 14-day period. Subtle treatment effects were observed in the macrofaunal community and sediment characteristics, which in turn resulted in subtle shifts in chlorophyll a (chl a) corrected gross primary production. However, there were no significant impacts on the key benthic species (the suspension-feeder Austrovenus stutchburyi and the deposit-feeder Macomona liliana) at this site, which is likely the reason more significant treatment effects were not observed in the measures of ecosystem function. Significant temporal variation was measured in most sediment properties (all except for phaeophytin), and also in benthic primary production. This study emphasized the importance of temporal variability when measuring ecosystem functions in shallow intertidal environments.

A second manipulative field experiment examined the impact of different quantities of Ulva detritus (low [60 g dw m-2], medium [120 g dw m-2] and high [240 g dw m-2]) on the sediment properties, benthic community composition and ecosystem functions of an estuarine benthic community. Plots were sampled on three occasions over an 8-week period, to examine changes in macrofauna and/or ecosystem functions over time. The only significant treatment effect was less gross ammonium flux from the sediment in procedural controls compared to low density treatments. Although no further significant treatment effects were detected, important temporal variation was observed. The macrofaunal community varied significantly between all three the sampling dates, while gross primary production, sediment oxygen consumption, and nutrient efflux from the light and dark chambers varied between at least two of the sampling dates. The results from this study again highlighted the important temporal changes that can be observed over relatively short time scales, and the importance of measuring temporal variation, particularly when measuring ecosystem functions such as primary production and benthic metabolism.

Finally, in a laboratory study, I examined the density dependent effects of two key intertidal bivalve species (A. stutchburyi and M. liliana) and their associated communities on the breakdown, loss, burial and uptake of Ulva detritus. Results showed that the site dominated by A. stutchburyi (AS) had higher overall chl a biomass and chl a was distributed evenly throughout the sediment profile, whilst less labelled Ulva was retained in the sediment. Both chl a biomass and the amount of Ulva recovered were correlated with the density of M. liliana, but only in cores collected from AS sites. Cores collected from the M. liliana dominated site (ML) showed an exponential decline in chl a with depth, and chl a biomass was negatively correlated with species richness. In ML cores (which had very low A. stutchburyi abundances), M. liliana densities showed no correlation with chl a biomass or the amount of Ulva that was recovered, which suggested that the community present in cores from AS is important in facilitating the impact by M. liliana on the mixing and the reworking of organic matter. These results emphasize the value of considering whole communities, and not just key species, when trying to understand sediment mixing and organic matter processing.

Although the addition of Ulva did not result in large and obvious shifts in community composition or ecosystem function, small subtle shifts were observed. These results underpinned the complex nature of biotic and abiotic interactions in dynamic systems like estuaries, but show that for the most part, ecosystem functions are robust. Temporal variations in ecosystem functions appeared to be largely driven by environmental conditions such as light availability, and were a more prominent driver in the differences observed in ecosystem function compared to treatment effects of Ulva addition. The results also highlighted the importance of community composition in the processing and reworking of macroalgal detritus, which further emphasized the complexity of estuarine systems. The results from this research suggest that on intertidal sandflats, providing the abundances of key species remain intact, the benthic community composition can shift, and species can be lost, without a significant loss or shift in overall ecosystem function.

year: 2018

title: Caring for our oceans and their biodiversity

authors: Daya-Winterbottom, Trevor

abstract: This paper will explore and critically analyse national strategies for oceans governance and protecting marine biodiversity from a transnational perspective. For example, during 2016 New Zealand launched a public consultation exercise regarding a new Marine Protected Areas Act,¹ and published statistical reports on the marine environment² and the marine economy³ and a biodiversity action plan.⁴ These policy developments have provided the catalyst for discussion about introducing a new Marine Protected Areas Act, and have provided a firm basis for participating in the United Nations process for a new international agreement for protecting marine biodiversity in areas beyond national jurisdiction. Looking at these New Zealand policy developments from a transnational perspective will firmly ground this paper in terms of considering how international environmental law obligations are implemented through both vertical comparison with the international legal order, and horizontal comparison between jurisdictions.

text: Caring for our oceans and their biodiversity This paper will explore and critically analyse national strategies for oceans governance and protecting marine biodiversity from a transnational perspective. For example, during 2016 New Zealand launched a public consultation exercise regarding a new Marine Protected Areas Act,¹ and published statistical reports on the marine environment² and the marine economy³ and a biodiversity action plan.⁴ These policy developments have provided the catalyst for discussion about introducing a new Marine Protected Areas Act, and have provided a firm basis for participating in the United Nations process for a new international agreement for protecting marine biodiversity in areas beyond national jurisdiction. Looking at these New Zealand policy developments from a transnational perspective will firmly ground this paper in terms of considering how international environmental law obligations are implemented through both vertical comparison with the international legal order, and horizontal comparison between jurisdictions.

year: 2020

title: Māori Women and Gambling: Every Day is a War Day!

authors: Morrison, Laurie Elena

subjects: Maori

abstract: This study was concerned with the health implications of new forms of gambling such as casinos, pokie machines and internet gambling for Māori women and their families in Auckland and the Bay of Plenty region of Aotearoa (New Zealand). It set out to discover what culturally appropriate services were available and the extent to which Māori women gamblers were utilising them. The literature documenting Māori perceptions of gambling shows that Māori women gamblers and their partner/whānau members and gambling service providers have been little studied previously.
These goals translated into the following specific aims: 1) to study how Māori women problem gamblers, their partner or whānau members and key informants perceived gambling, what it meant to them and why they did it; 2) to investigate the consequences of gambling for Māori women, whānau and service providers in dealing with the effects of gambling; 3) to report on how these three groups dealt with the effects of gambling; and 4) to discover what helped to bring about positive changes for the three groups.
 All of the aims were achieved. 
A Māori approach (Kaupapa Māori), combined with a naturalistic approach to data collection, was adopted. Qualitative methods are most appropriate to use when working with some Māori, as there is a growing realisation that research with Māori needs to be interactive. A Māori research procedure modelled on the ritual ceremony of encounter (Pōwhiri) provided an appropriate structure for the development and presentation of the research process. The major focus was on the qualitative data obtained from semi-structured interviews in two locations - Rotorua and Auckland. The interviews were conducted with twenty Māori women gamblers, sixteen whānau members including partners and ten interviews with staff involved in services that provided help for problem gamblers. The three interview schedules were based on a number of broad themes and open-ended questions to obtain meaningful descriptive data. The interviews were audio recorded and used to produce transcripts that were then sent back to the participants for feedback. Qualitative data analysis was conducted on the returned documents. 
The findings from this study revealed major impacts of the women's socio-economic, familial and societal circumstances on gambling behaviour and its effects, which are areas of concern for mental health professionals and researchers. The mythical Māori canoes on which Māori voyaged from their place of origin (Hawaiiki) to Aotearoa, the Waka, provided an appropriate metaphor to present the interrelationship between the pull and push factors toward gambling, and its implications for society. This is illustrated as a spinning waka, Te Waka Hūrihuri. On the other hand, Te Waka Māia (courageous) demonstrates the relationships between the variables that help Māori women gamblers to cope and helpful strategies found to assist them to modify or stop their gambling behaviour. It is recommended that the government limit the proliferation of gaming venues and continue to encourage development of emerging Māori services. Moreover, a coordinated approach is essential, as Māori women gamblers, partners and whānau members need to heal together for positive outcomes for Māori health development in Aotearoa. 
The main implication of this study is that a wide range of further research into Māori and gambling is required. Recommendations on ways in which the current delivery of services in Rotorua and Auckland could be improved are:
 	That the Ministry of Health purchase services that establish support groups for Māori people with problem gambling and their whānau, and
 	That non-Māori provider services and organisations support the development of emerging Māori services.
Heeding the outcome of this research should help improve New Zealand's existing health policy and capacity for Māori women's health development. It should also enrich our understanding of the adaptation patterns of Māori whānau member/s, and thus should have implications, not only for Māori health policies, but also relevance for the wider field of international cross-comparative research on indigenous gambling and mental health issues.  Limitations of this study included a small, localised sample that means the findings can only tentatively be generalised to the wider population of Māori women gamblers. Nonetheless, information gained from the study contributes to understanding of the adaptation patterns of Māori women gamblers, their whānau member/s, and those who are trying to help them.  It is hoped that the study will make it at least a little less true that  every day is a war day  for Māori women and their whānau trying to deal with the problem of gambling.

text: Māori Women and Gambling: Every Day is a War Day! This study was concerned with the health implications of new forms of gambling such as casinos, pokie machines and internet gambling for Māori women and their families in Auckland and the Bay of Plenty region of Aotearoa (New Zealand). It set out to discover what culturally appropriate services were available and the extent to which Māori women gamblers were utilising them. The literature documenting Māori perceptions of gambling shows that Māori women gamblers and their partner/whānau members and gambling service providers have been little studied previously.
These goals translated into the following specific aims: 1) to study how Māori women problem gamblers, their partner or whānau members and key informants perceived gambling, what it meant to them and why they did it; 2) to investigate the consequences of gambling for Māori women, whānau and service providers in dealing with the effects of gambling; 3) to report on how these three groups dealt with the effects of gambling; and 4) to discover what helped to bring about positive changes for the three groups.
 All of the aims were achieved. 
A Māori approach (Kaupapa Māori), combined with a naturalistic approach to data collection, was adopted. Qualitative methods are most appropriate to use when working with some Māori, as there is a growing realisation that research with Māori needs to be interactive. A Māori research procedure modelled on the ritual ceremony of encounter (Pōwhiri) provided an appropriate structure for the development and presentation of the research process. The major focus was on the qualitative data obtained from semi-structured interviews in two locations - Rotorua and Auckland. The interviews were conducted with twenty Māori women gamblers, sixteen whānau members including partners and ten interviews with staff involved in services that provided help for problem gamblers. The three interview schedules were based on a number of broad themes and open-ended questions to obtain meaningful descriptive data. The interviews were audio recorded and used to produce transcripts that were then sent back to the participants for feedback. Qualitative data analysis was conducted on the returned documents. 
The findings from this study revealed major impacts of the women's socio-economic, familial and societal circumstances on gambling behaviour and its effects, which are areas of concern for mental health professionals and researchers. The mythical Māori canoes on which Māori voyaged from their place of origin (Hawaiiki) to Aotearoa, the Waka, provided an appropriate metaphor to present the interrelationship between the pull and push factors toward gambling, and its implications for society. This is illustrated as a spinning waka, Te Waka Hūrihuri. On the other hand, Te Waka Māia (courageous) demonstrates the relationships between the variables that help Māori women gamblers to cope and helpful strategies found to assist them to modify or stop their gambling behaviour. It is recommended that the government limit the proliferation of gaming venues and continue to encourage development of emerging Māori services. Moreover, a coordinated approach is essential, as Māori women gamblers, partners and whānau members need to heal together for positive outcomes for Māori health development in Aotearoa. 
The main implication of this study is that a wide range of further research into Māori and gambling is required. Recommendations on ways in which the current delivery of services in Rotorua and Auckland could be improved are:
 	That the Ministry of Health purchase services that establish support groups for Māori people with problem gambling and their whānau, and
 	That non-Māori provider services and organisations support the development of emerging Māori services.
Heeding the outcome of this research should help improve New Zealand's existing health policy and capacity for Māori women's health development. It should also enrich our understanding of the adaptation patterns of Māori whānau member/s, and thus should have implications, not only for Māori health policies, but also relevance for the wider field of international cross-comparative research on indigenous gambling and mental health issues.  Limitations of this study included a small, localised sample that means the findings can only tentatively be generalised to the wider population of Māori women gamblers. Nonetheless, information gained from the study contributes to understanding of the adaptation patterns of Māori women gamblers, their whānau member/s, and those who are trying to help them.  It is hoped that the study will make it at least a little less true that  every day is a war day  for Māori women and their whānau trying to deal with the problem of gambling.

year: 2008