title: Are zooplankton invasions in constructed waters facilitated by simple communities?

authors: Parkes, Samantha Maree

subjects: zooplankton

abstract: The invasion of non-indigenous species is considered to be one of the leading causes of biodiversity loss globally. My research aimed to determine if constructed water bodies (e.g., water supply reservoirs, dams and ponds) were invaded by zooplankton with greater ease than natural water bodies, and whether this was due to a lower biodiversity, and therefore lower 'biotic resistance', in constructed water bodies. Sediment cores were collected from a cross-section of 46 lakes, ponds and reservoirs (23 natural and 23 constructed) throughout the North Island, New Zealand. Diapausing zooplankton eggs were separated from the sediments and hatched to assess species composition and richness. In addition, the distributions of non-indigenous zooplankton were examined to determine if they occurred more frequently in constructed water bodies than in natural ones.
Species composition results showed that natural water body zooplankton communities appeared to consist mainly of a core group of truly planktonic species. However, the species assemblages of constructed water bodies were more varied, comprising of a number of littoral and benthic species, and a large number of species that were recorded from only a single water body. A canonical correspondence analysis indicated that Trophic Level Index explained a significant amount of variation in zooplankton community composition of natural waters (p = 0.002). Distance to nearest water body and number of water bodies within a 20 km radius explained significant amounts of variation in community composition of constructed water bodies (p = 0.040 and 0.038 respectively). Average species richness was slightly higher for natural water bodies than constructed water bodies (18.47 and 15.05 respectively), although overall there was a lot of variation for both natural and constructed water body datasets. A stepwise linear regression indicated that latitude and approximate maximum depth of water body were significant predictors of natural water body species richness (p = 0.002 and 0.016 respectively). However, no significant predictors of species richness were elucidated for constructed water bodies. The non-indigenous calanoid copepods Sinodiaptomus valkanovi and Boeckella minuta were only found in constructed water bodies. However, the non-indigenous cladoceran Daphnia galeata was recorded in both natural and constructed water bodies. The non-indigenous calanoid copepods are more likely to establish populations in constructed water bodies due to the absence of key species (i.e. native calanoid copepods), whose presence in natural waters seemingly provides 'biotic resistance'. The invasion success of D. galeata in constructed and natural waters may be attributed to the absence of a superior competitor, as native Daphnia populations, for example, are rare in the North Island.
My results suggest that species richness may not be as important as species composition in influencing the ease with which non-indigenous species invade constructed water bodies. The core group of species found in natural water bodies are likely to be better adapted to pelagic conditions, and therefore better at resisting invaders, than the more varied constructed water body assemblages.

text: Are zooplankton invasions in constructed waters facilitated by simple communities? The invasion of non-indigenous species is considered to be one of the leading causes of biodiversity loss globally. My research aimed to determine if constructed water bodies (e.g., water supply reservoirs, dams and ponds) were invaded by zooplankton with greater ease than natural water bodies, and whether this was due to a lower biodiversity, and therefore lower 'biotic resistance', in constructed water bodies. Sediment cores were collected from a cross-section of 46 lakes, ponds and reservoirs (23 natural and 23 constructed) throughout the North Island, New Zealand. Diapausing zooplankton eggs were separated from the sediments and hatched to assess species composition and richness. In addition, the distributions of non-indigenous zooplankton were examined to determine if they occurred more frequently in constructed water bodies than in natural ones.
Species composition results showed that natural water body zooplankton communities appeared to consist mainly of a core group of truly planktonic species. However, the species assemblages of constructed water bodies were more varied, comprising of a number of littoral and benthic species, and a large number of species that were recorded from only a single water body. A canonical correspondence analysis indicated that Trophic Level Index explained a significant amount of variation in zooplankton community composition of natural waters (p = 0.002). Distance to nearest water body and number of water bodies within a 20 km radius explained significant amounts of variation in community composition of constructed water bodies (p = 0.040 and 0.038 respectively). Average species richness was slightly higher for natural water bodies than constructed water bodies (18.47 and 15.05 respectively), although overall there was a lot of variation for both natural and constructed water body datasets. A stepwise linear regression indicated that latitude and approximate maximum depth of water body were significant predictors of natural water body species richness (p = 0.002 and 0.016 respectively). However, no significant predictors of species richness were elucidated for constructed water bodies. The non-indigenous calanoid copepods Sinodiaptomus valkanovi and Boeckella minuta were only found in constructed water bodies. However, the non-indigenous cladoceran Daphnia galeata was recorded in both natural and constructed water bodies. The non-indigenous calanoid copepods are more likely to establish populations in constructed water bodies due to the absence of key species (i.e. native calanoid copepods), whose presence in natural waters seemingly provides 'biotic resistance'. The invasion success of D. galeata in constructed and natural waters may be attributed to the absence of a superior competitor, as native Daphnia populations, for example, are rare in the North Island.
My results suggest that species richness may not be as important as species composition in influencing the ease with which non-indigenous species invade constructed water bodies. The core group of species found in natural water bodies are likely to be better adapted to pelagic conditions, and therefore better at resisting invaders, than the more varied constructed water body assemblages.

year: 2010

title: MacKinder meets Buzan: A Geopolitical Extension to Security complex Theory with an emphasis on the Polar Regions

authors: Gibbs, Denis Richard

subjects: Shatterbelts

abstract: Throughout the centuries interstate wars have been fought over territory to satisfy the requirement of states’ to secure sufficient land and resources to meet the lifestyle needs and economic aspirations of their citizens. While in the past, the conditions precipitating war were predominantly anthropogenic in their origin, in the twenty-first century, wars are increasingly likely to be the consequence of worldwide environmental degradation. Two environmental conditions that have paralleled humanity’s unceasing drive for wealth and prosperity are becoming significant threats to the security of every state: these threats are global climate change and natural resource scarcity. Although these two threats are global in stature, their impact will initially influence security interdependencies at the state and regional levels. Regional security complex theory is a methodological attempt to explain why traditional – military and political – security interdependencies trigger the aggregation of geographically contiguous states into regional groupings defined by the social condition of amity or enmity. However, strictures embedded within this typology prevent the same methodology from being used to explain regionalisation when threats arise from non-traditional sources or the affected states lack geographic contiguity. To overcome this methodological impediment, this thesis proposes a theoretical enlargement – a “hybrid” theory – which combines methodologies drawn from sector security analysis with essential elements of “externalities” and “Shatterbelts” drawn from Regional Orders and Geopolitics ontologies respectively. To test the authority of the “hybrid” theory, two futuristic scenarios are composed, each representing a possible, even probable, future for the two Polar Regions. Each scenario depicts the world in the year 2035, when the human population and individual wealth will likely be of a magnitude greater than they are today and when the world is also detrimentally affected by an increasingly inclement climate and the declining availability of natural resources. Common to both scenarios are potential changes to the political world order and the growing worldwide influence of emerging great powers in Asia and Latin America. In the contemporary Arctic, the future is already being determined by the inimical politics of oil. In a scenario where the Arctic region has become progressively less sanguine, the “hybrid” theory suggests that antagonisms between Arctic-rim countries will forge the establishment of at least one security complex. There will, therefore, be a security response to the region-wide competition for resources. As the twenty-first century unfolds, the presence in the Arctic of non-Arctic states as resource competitors heightens the probability that established security complexes will transmute into conflict prone shatterbelts. The Antarctic Treaty currently prohibits both the commercialisation and militarisation of the continent. It is an institutional regime that is not due to be reviewed until mid-century. Antarctica is a continent like no other for its legal status remains ill-defined and the existing seven territorial claims attract no universal endorsement. Given this political environment, the “hybrid” theory suggests, that in a world experiencing a severe shortage of resources no security complex will form in Antarctica but, instead the region will become a shatterbelt or the loci for resource wars.

text: MacKinder meets Buzan: A Geopolitical Extension to Security complex Theory with an emphasis on the Polar Regions Throughout the centuries interstate wars have been fought over territory to satisfy the requirement of states’ to secure sufficient land and resources to meet the lifestyle needs and economic aspirations of their citizens. While in the past, the conditions precipitating war were predominantly anthropogenic in their origin, in the twenty-first century, wars are increasingly likely to be the consequence of worldwide environmental degradation. Two environmental conditions that have paralleled humanity’s unceasing drive for wealth and prosperity are becoming significant threats to the security of every state: these threats are global climate change and natural resource scarcity. Although these two threats are global in stature, their impact will initially influence security interdependencies at the state and regional levels. Regional security complex theory is a methodological attempt to explain why traditional – military and political – security interdependencies trigger the aggregation of geographically contiguous states into regional groupings defined by the social condition of amity or enmity. However, strictures embedded within this typology prevent the same methodology from being used to explain regionalisation when threats arise from non-traditional sources or the affected states lack geographic contiguity. To overcome this methodological impediment, this thesis proposes a theoretical enlargement – a “hybrid” theory – which combines methodologies drawn from sector security analysis with essential elements of “externalities” and “Shatterbelts” drawn from Regional Orders and Geopolitics ontologies respectively. To test the authority of the “hybrid” theory, two futuristic scenarios are composed, each representing a possible, even probable, future for the two Polar Regions. Each scenario depicts the world in the year 2035, when the human population and individual wealth will likely be of a magnitude greater than they are today and when the world is also detrimentally affected by an increasingly inclement climate and the declining availability of natural resources. Common to both scenarios are potential changes to the political world order and the growing worldwide influence of emerging great powers in Asia and Latin America. In the contemporary Arctic, the future is already being determined by the inimical politics of oil. In a scenario where the Arctic region has become progressively less sanguine, the “hybrid” theory suggests that antagonisms between Arctic-rim countries will forge the establishment of at least one security complex. There will, therefore, be a security response to the region-wide competition for resources. As the twenty-first century unfolds, the presence in the Arctic of non-Arctic states as resource competitors heightens the probability that established security complexes will transmute into conflict prone shatterbelts. The Antarctic Treaty currently prohibits both the commercialisation and militarisation of the continent. It is an institutional regime that is not due to be reviewed until mid-century. Antarctica is a continent like no other for its legal status remains ill-defined and the existing seven territorial claims attract no universal endorsement. Given this political environment, the “hybrid” theory suggests, that in a world experiencing a severe shortage of resources no security complex will form in Antarctica but, instead the region will become a shatterbelt or the loci for resource wars.

year: 2011

title: The Determinants of Tribal Population Growth in the New Zealand Census

authors: Rarere, Moana

subjects: tribal population growth

abstract: By the early twentieth century the notion that ethnic populations would dissipate was a commonly held belief.  However, after World War II, the modern world has seen an incredible resurgence in ethnic identities.  Ethnic conflicts, mobilisations, and the political movements of the 1950s and 1960s served as a major catalyst in the diffusion of indigenous identities and rights.  Consequently, indigenous groups in settler states, especially in North America, experienced population growth beyond the levels of natural demographic factors, that is, fertility, mortality and migration.  Researchers attributed a significant proportion of this growth to changing patterns of ethnic identification, also referred to as ethnic mobility .  Although this phenomenon is well documented in North America, it is only just beginning to be understood in relation to the New Zealand context. 

During the 1970s and 1980s, the indigenous Māori population of New Zealand gained substantial progress in political, social and economic spheres, following the same patterns of ethnic identity growth as in North America.  Despite these gains, the average individual socio-economic outcomes for Māori remain poor, especially in comparison to New Zealand Europeans/Pākehā.  Through key legislation, iwi (tribal) organisations became the core mechanism in which to address Māori socio-economic issues, achieve Māori aspirations and to manage Treaty of Waitangi settlement monies.  Subsequently, the need for iwi statistics for policy and planning purposes saw the reinstatement of iwi data in the New Zealand census in 1991.  Surprisingly, however, very little attention has been given to contemporary patterns of iwi demography.

Since the 1991 census, observations of total iwi population growth patterns indicate these patterns cannot solely be explained by natural demographic factors.  Furthermore, the growth trajectories of individual iwi were markedly different, and in some cases erratic.  These initial observations have raised the following key research questions: What do patterns of iwi growth look like?  What is the role of ethnic mobility?  What factors drive ethnic mobility?  Who changes iwi identification?  Why should we care?  

This thesis examines patterns of iwi identification in the New Zealand Census of Population and Dwellings from 1991 to 2006.  It uses statistical methods to not only document iwi population changes but to also identify the key determinants driving these trajectories.  In addition, this thesis considers ethnic mobility as an important driver of population growth but, situates this within the broader macro-political environment.  Along with the analysis of aggregate iwi population changes, this thesis also provides an in-depth analysis of four iwi groups – Ngāi Tahu, Waikato, Ngāti Awa and Tūhoe, in order to observe individual iwi dynamics that are not clearly visible at the aggregate level.

The findings of this thesis raise important implications for theories of ethnicity and the demographic study of ethnic populations.  For example, this thesis argues that the category of ethnic mobility is mainly contextual, that is, decisions to change ethnic responses are influenced by the broader political, social and economic contexts.  Furthermore this thesis contends that individual ethnic identification decisions are for the most part defined by ethnic categories imposed by the State.  While traditional views suggest ethnicity is fixed, intrinsic and kinship based, this thesis finds significant support for contemporary views that argue ethnicity is fluid, extrinsic and socially constructed.  Rather than reject traditional views of Maori identity, this study recognises that ethnic identities are complex, and that shifts in iwi identification is about connecting and reconnecting with whakapapa.  Thus this thesis argues that in order to understand individual iwi dynamics both points of view need to be considered.

text: The Determinants of Tribal Population Growth in the New Zealand Census By the early twentieth century the notion that ethnic populations would dissipate was a commonly held belief.  However, after World War II, the modern world has seen an incredible resurgence in ethnic identities.  Ethnic conflicts, mobilisations, and the political movements of the 1950s and 1960s served as a major catalyst in the diffusion of indigenous identities and rights.  Consequently, indigenous groups in settler states, especially in North America, experienced population growth beyond the levels of natural demographic factors, that is, fertility, mortality and migration.  Researchers attributed a significant proportion of this growth to changing patterns of ethnic identification, also referred to as ethnic mobility .  Although this phenomenon is well documented in North America, it is only just beginning to be understood in relation to the New Zealand context. 

During the 1970s and 1980s, the indigenous Māori population of New Zealand gained substantial progress in political, social and economic spheres, following the same patterns of ethnic identity growth as in North America.  Despite these gains, the average individual socio-economic outcomes for Māori remain poor, especially in comparison to New Zealand Europeans/Pākehā.  Through key legislation, iwi (tribal) organisations became the core mechanism in which to address Māori socio-economic issues, achieve Māori aspirations and to manage Treaty of Waitangi settlement monies.  Subsequently, the need for iwi statistics for policy and planning purposes saw the reinstatement of iwi data in the New Zealand census in 1991.  Surprisingly, however, very little attention has been given to contemporary patterns of iwi demography.

Since the 1991 census, observations of total iwi population growth patterns indicate these patterns cannot solely be explained by natural demographic factors.  Furthermore, the growth trajectories of individual iwi were markedly different, and in some cases erratic.  These initial observations have raised the following key research questions: What do patterns of iwi growth look like?  What is the role of ethnic mobility?  What factors drive ethnic mobility?  Who changes iwi identification?  Why should we care?  

This thesis examines patterns of iwi identification in the New Zealand Census of Population and Dwellings from 1991 to 2006.  It uses statistical methods to not only document iwi population changes but to also identify the key determinants driving these trajectories.  In addition, this thesis considers ethnic mobility as an important driver of population growth but, situates this within the broader macro-political environment.  Along with the analysis of aggregate iwi population changes, this thesis also provides an in-depth analysis of four iwi groups – Ngāi Tahu, Waikato, Ngāti Awa and Tūhoe, in order to observe individual iwi dynamics that are not clearly visible at the aggregate level.

The findings of this thesis raise important implications for theories of ethnicity and the demographic study of ethnic populations.  For example, this thesis argues that the category of ethnic mobility is mainly contextual, that is, decisions to change ethnic responses are influenced by the broader political, social and economic contexts.  Furthermore this thesis contends that individual ethnic identification decisions are for the most part defined by ethnic categories imposed by the State.  While traditional views suggest ethnicity is fixed, intrinsic and kinship based, this thesis finds significant support for contemporary views that argue ethnicity is fluid, extrinsic and socially constructed.  Rather than reject traditional views of Maori identity, this study recognises that ethnic identities are complex, and that shifts in iwi identification is about connecting and reconnecting with whakapapa.  Thus this thesis argues that in order to understand individual iwi dynamics both points of view need to be considered.

year: 2012