title: Identifying temporal and spatial variations in the binding properties of transition metal-organic ligand complexes in cave waters using organic inclusions in speleothem calcite: Implications for paleoclimate research.

authors: Brodnax, Robert

subjects: speleothems

abstract: Speleothems such as stalagmites, stalactites and flowstones, contain paleoclimate information encoded in their geochemical properties. One of these properties, transition metal abundance in speleothem calcite, is tightly controlled by complexation reactions in cave water with dissolved organic matter (DOM). Organic compounds are also preserved in speleothem deposits. DOM structure varies from cave system to cave system and over time, but whether these structural variations meaningfully alter the way DOM controls trace metal incorporation into calcite is unclear. This is relevant to the development of speleothem transition metal content as a paleoclimate proxy, particularly over large spatial and temporal scales where DOM structure variations are likely. This study identifies variations in the binding properties of DOM preserved in speleothem calcite over time and space by extracting organic compounds of known age and origin from speleothems collected from New Zealand, Niuean, British, and Australian cave systems. The kinetic properties of DOM complexes from these extracts were measured using small volume diffusive gradients in thin films (SV-DGT) and the variation in the binding strength of complexes with Cu, Co, and Ni was compared across time and space. DOM binding of Cu and Co were found to vary significantly depending on the cave system from which the DOM originated. Whether this variation was linked to climate changes represented in the age of the DOM or to changes in system characteristics related to geographical setting was unclear. Despite this, it is apparent that there are factors related to the origin of DOM in cave systems that influence the kinetic restrictions applied to transition metals in cave water. This variability should be considered when linking trace element contents in cave precipitates to paleoclimate change.

text: Identifying temporal and spatial variations in the binding properties of transition metal-organic ligand complexes in cave waters using organic inclusions in speleothem calcite: Implications for paleoclimate research. Speleothems such as stalagmites, stalactites and flowstones, contain paleoclimate information encoded in their geochemical properties. One of these properties, transition metal abundance in speleothem calcite, is tightly controlled by complexation reactions in cave water with dissolved organic matter (DOM). Organic compounds are also preserved in speleothem deposits. DOM structure varies from cave system to cave system and over time, but whether these structural variations meaningfully alter the way DOM controls trace metal incorporation into calcite is unclear. This is relevant to the development of speleothem transition metal content as a paleoclimate proxy, particularly over large spatial and temporal scales where DOM structure variations are likely. This study identifies variations in the binding properties of DOM preserved in speleothem calcite over time and space by extracting organic compounds of known age and origin from speleothems collected from New Zealand, Niuean, British, and Australian cave systems. The kinetic properties of DOM complexes from these extracts were measured using small volume diffusive gradients in thin films (SV-DGT) and the variation in the binding strength of complexes with Cu, Co, and Ni was compared across time and space. DOM binding of Cu and Co were found to vary significantly depending on the cave system from which the DOM originated. Whether this variation was linked to climate changes represented in the age of the DOM or to changes in system characteristics related to geographical setting was unclear. Despite this, it is apparent that there are factors related to the origin of DOM in cave systems that influence the kinetic restrictions applied to transition metals in cave water. This variability should be considered when linking trace element contents in cave precipitates to paleoclimate change.

year: 2024

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: Harakeke (Phormium tenax) ecology and historical management by Maori: The changing landscape in New Zealand

authors: Wehi, Priscilla M.

subjects: ethnobotany

abstract: Harakeke (Phormium tenax: Phormiaceae) is an important weaving resource for the indigenous Maori people of New Zealand. This research project investigates Maori knowledge of harakeke ecology and management practices prior to the early 20th century within the context of a study of relevant environmental parameters that limit its natural distribution. Ecological information referring to harakeke was analysed from interviews with elders and ancestral sayings (whakatauki). As well, documents from the late 181h to the early 20th century were examined, and environmental parameters for both harakeke and wharariki (Phormium cookianum) were quantified and analysed using correlative models. 
Interviews with 11 elders (from Waikato and Northland) identified key issues in harakeke management, including 'correct' harvesting procedures, use of natural harakeke stands, and specific use of different varieties. Planting practices varied regionally. Three different methods of excess harakeke disposal were reported, including burning. The 15 whakatauki analysed emphasise the interconnectedness of ecosystems, including pollinator-plant relationships for kaka and bellbirds. Four whakataukirefer to environmental tolerances for harakeke and two to the use of fire to stimulate harakeke growth. Others refer to competition between shoots, nutrient requirements, and the growth and multiplication of harakeke offsets. 
Numerous early reports indicate that harakeke has been cultivated throughout much of New Zealand, with cultivations ranging in size from a few bushes to at least several acres. Thirty six varieties were linked to specific weaving uses. Twenty varieties were cultivated, but ten prized fibre varieties were also harvested from natural stands. Numbers of recorded varieties varied between districts, with 31 recorded in Taranaki but only two recorded by name for Northland. Valued varieties, including raumoa and oue, were dispersed throughout the North Island. Mapping different varieties revealed a wide spatial spread for varieties such as rataroa and oue. Specific management techniques included seed germination as well as vegetative propagation. Early records of harakeke pests were not found. Records of harakeke irrigation and the use of fire indicate that Maori created suitable conditions for new cultivations or pii harakeke, which may also have prevented insect infestation. Cumulatively, there is evidence of extensive active management of harakeke. Wharariki and harakeke were found to have distinct environmental niches, with wharariki better able to withstand cooler temperatures, higher rainfall and greater frequency of ground frost than harakeke.
Predictive mapping of harakeke for the northern region of New Zealand shows a low probability of naturally occurring harakeke in much of the Northland and Waikato interior, and a high probability in coastal areas with warm temperatures. It seems likely that Maori transported harakeke into areas where it was unlikely to have occurred naturally and that some apparently 'natural' stands ofharakeke were created and maintained by Maori.
Maori cultivation, dispersal and active management of harakeke, as well as possible creation of wetland areas, emphasises the importance of harakeke as an economic resource prior to European colonisation, and indicates how the New Zealand landscape may have been transformed. Maori ecological knowledge can contribute new perspectives to restoration ecology and ecosystem research.

text: Harakeke (Phormium tenax) ecology and historical management by Maori: The changing landscape in New Zealand Harakeke (Phormium tenax: Phormiaceae) is an important weaving resource for the indigenous Maori people of New Zealand. This research project investigates Maori knowledge of harakeke ecology and management practices prior to the early 20th century within the context of a study of relevant environmental parameters that limit its natural distribution. Ecological information referring to harakeke was analysed from interviews with elders and ancestral sayings (whakatauki). As well, documents from the late 181h to the early 20th century were examined, and environmental parameters for both harakeke and wharariki (Phormium cookianum) were quantified and analysed using correlative models. 
Interviews with 11 elders (from Waikato and Northland) identified key issues in harakeke management, including 'correct' harvesting procedures, use of natural harakeke stands, and specific use of different varieties. Planting practices varied regionally. Three different methods of excess harakeke disposal were reported, including burning. The 15 whakatauki analysed emphasise the interconnectedness of ecosystems, including pollinator-plant relationships for kaka and bellbirds. Four whakataukirefer to environmental tolerances for harakeke and two to the use of fire to stimulate harakeke growth. Others refer to competition between shoots, nutrient requirements, and the growth and multiplication of harakeke offsets. 
Numerous early reports indicate that harakeke has been cultivated throughout much of New Zealand, with cultivations ranging in size from a few bushes to at least several acres. Thirty six varieties were linked to specific weaving uses. Twenty varieties were cultivated, but ten prized fibre varieties were also harvested from natural stands. Numbers of recorded varieties varied between districts, with 31 recorded in Taranaki but only two recorded by name for Northland. Valued varieties, including raumoa and oue, were dispersed throughout the North Island. Mapping different varieties revealed a wide spatial spread for varieties such as rataroa and oue. Specific management techniques included seed germination as well as vegetative propagation. Early records of harakeke pests were not found. Records of harakeke irrigation and the use of fire indicate that Maori created suitable conditions for new cultivations or pii harakeke, which may also have prevented insect infestation. Cumulatively, there is evidence of extensive active management of harakeke. Wharariki and harakeke were found to have distinct environmental niches, with wharariki better able to withstand cooler temperatures, higher rainfall and greater frequency of ground frost than harakeke.
Predictive mapping of harakeke for the northern region of New Zealand shows a low probability of naturally occurring harakeke in much of the Northland and Waikato interior, and a high probability in coastal areas with warm temperatures. It seems likely that Maori transported harakeke into areas where it was unlikely to have occurred naturally and that some apparently 'natural' stands ofharakeke were created and maintained by Maori.
Maori cultivation, dispersal and active management of harakeke, as well as possible creation of wetland areas, emphasises the importance of harakeke as an economic resource prior to European colonisation, and indicates how the New Zealand landscape may have been transformed. Maori ecological knowledge can contribute new perspectives to restoration ecology and ecosystem research.

year: 2005