title: Do benthic macrofauna functional groups or their key constituent species better predict variation in ecosystem functioning?

authors: Petersen, Grady

subjects: Marine science

abstract: Estuarine ecosystems are important zones for primary productivity and nutrient processing, have rich communities of plants and animals and support important fisheries and are fundamental to food webs. Intertidal habitats in estuaries are highly dynamic environments, subject to tidal variation and often have strong environmental gradients of salinity, turbidity and bed sediment grain size. These environmental factors contribute to the diversity of macrofaunal assemblages which vary over a range of spatial and temporal scales. This study was based in the Manukau Harbour, New Zealand, and aimed to investigate the spatial variation of nutrient processing within the harbour, and whether this variation is best explained by biotic or abiotic variables. Additionally, DistLM models were employed to find if either macrofauna functional groups or key species in these groups serve as better predictors of ecosystem function.
To provide empirical information to a project designing a whole-estuary nutrient mixing model, a team of ecologists deployed benthic incubation chambers (0.25 m2) to measure solute fluxes, and assessed the macrofauna community and sediment characteristics at 6 intertidal sandflat sites in the Manukau Harbour over a 4 day period in December 2016. Denitrification rates were measured at 2 sites to provide information on nitrogen removal from the harbour. This thesis deals specifically with how the macrofaunal communities and how they relate to and influence nutrient fluxes.
Macrofauna collected from the Manukau Harbour were assigned functional groups based on species specific traits. Multiple regression models were performed using functional groups and ecosystem variables as predictors, and dark chamber fluxes of O2, NH4+ and NOx- as response variables. Significantly correlated functional groups (p < 0.05) were substituted for their constituent species to determine whether functional groups or individual species served as better predictors of ecosystem functioning. 
The results indicated that while functional groups may provide redundancy in terms of multiple species carrying out similar functional roles, there are key species that dominate these roles. In addition to the macrofauna functional groups, several environmental variables (mud content, phaeophytin biomass and organic content) served as important predictors for changes in ecosystem functioning. 
This suggests that macrofauna functional groups form complex relationships with environmental variables which influence ecosystem functioning through benthic metabolism and excretion and macrofaunally-mediated such as bioturbation and irrigation of sediments. These biological processes alter the oxic-anoxic boundaries and facilitate the breakdown and remineralisation of deposited organic matter, fuelling primary productivity and nitrogen cycling.
At two sites where denitrification was measured, the total amount of nitrogen leaving the water column was similar (242.3 and 234.8 µmol N m-2 h-1), however the rates of denitrification of these sites was significantly (p = 0.0001) different, suggesting that permanent removal of nitrogen varies spatially across the harbour, which can have important connotations for ecosystem management.

text: Do benthic macrofauna functional groups or their key constituent species better predict variation in ecosystem functioning? Estuarine ecosystems are important zones for primary productivity and nutrient processing, have rich communities of plants and animals and support important fisheries and are fundamental to food webs. Intertidal habitats in estuaries are highly dynamic environments, subject to tidal variation and often have strong environmental gradients of salinity, turbidity and bed sediment grain size. These environmental factors contribute to the diversity of macrofaunal assemblages which vary over a range of spatial and temporal scales. This study was based in the Manukau Harbour, New Zealand, and aimed to investigate the spatial variation of nutrient processing within the harbour, and whether this variation is best explained by biotic or abiotic variables. Additionally, DistLM models were employed to find if either macrofauna functional groups or key species in these groups serve as better predictors of ecosystem function.
To provide empirical information to a project designing a whole-estuary nutrient mixing model, a team of ecologists deployed benthic incubation chambers (0.25 m2) to measure solute fluxes, and assessed the macrofauna community and sediment characteristics at 6 intertidal sandflat sites in the Manukau Harbour over a 4 day period in December 2016. Denitrification rates were measured at 2 sites to provide information on nitrogen removal from the harbour. This thesis deals specifically with how the macrofaunal communities and how they relate to and influence nutrient fluxes.
Macrofauna collected from the Manukau Harbour were assigned functional groups based on species specific traits. Multiple regression models were performed using functional groups and ecosystem variables as predictors, and dark chamber fluxes of O2, NH4+ and NOx- as response variables. Significantly correlated functional groups (p < 0.05) were substituted for their constituent species to determine whether functional groups or individual species served as better predictors of ecosystem functioning. 
The results indicated that while functional groups may provide redundancy in terms of multiple species carrying out similar functional roles, there are key species that dominate these roles. In addition to the macrofauna functional groups, several environmental variables (mud content, phaeophytin biomass and organic content) served as important predictors for changes in ecosystem functioning. 
This suggests that macrofauna functional groups form complex relationships with environmental variables which influence ecosystem functioning through benthic metabolism and excretion and macrofaunally-mediated such as bioturbation and irrigation of sediments. These biological processes alter the oxic-anoxic boundaries and facilitate the breakdown and remineralisation of deposited organic matter, fuelling primary productivity and nitrogen cycling.
At two sites where denitrification was measured, the total amount of nitrogen leaving the water column was similar (242.3 and 234.8 µmol N m-2 h-1), however the rates of denitrification of these sites was significantly (p = 0.0001) different, suggesting that permanent removal of nitrogen varies spatially across the harbour, which can have important connotations for ecosystem management.

year: 2018

title: Volcanology of the basaltic lava succession within the Auckland pit of the Bombay Quarry, Bombay Volcanic Complex, South Auckland Volcanic Field

authors: Kapasi, Aliasgar

subjects: Volcanology

abstract: The South Auckland Volcanic Field (SAVF), which was active 1.59 – 0.51 million years ago and comprises around 82 volcanic centres, represents a complete history of a monogenetic field preserved in the geological record. The Auckland pit in the Bombay Quarry was recently exposed, revealing an infilled palaeovalley of volcanic and sedimentary deposits possibly associated with the nearby Bombay Volcanic Complex. A set of vertical drill cores from across the quarry were available for this study.
 
The stratigraphy of the volcanic and sedimentary deposits and the facies architecture were examined and described from the drill cores available, and a set of stratigraphic logs were produced. Volcanic and sedimentary units identified were: basement Waitemata and Tauranga group sediments, three individual ponded basalt lavas with intercalated scoria and Quaternary alluvium and/or Kauroa ash deposits. Facies identified include: moderately vesicular basalt (A.1), vesicular basalt with vesicle trails (A.2), non-vesicular basalt (A.3), poorly vesicular basalt (A.4), scoria deposit (B), scoriaceous basalt (C) and intercalated silt/clay (D).

Petrographic characteristics were analysed by optical microscopy, which show that all three basalt lavas have minerals comprising: olivine and clinopyroxene phenocrysts, and a groundmass of plagioclase, opaques and mafic minerals, however, the proportions of each mineral vary between samples. Olivine, clinopyroxene and plagioclase elemental compositions for each of the three basalt units were determined by electron microprobe analysis and revealed that the middle basalt had relatively lower proportion of Mg- and Ca-rich minerals compared to the upper and lower basalts. Furthermore, mineral compositions were consistent with the broad group B rock type of the SAVF lavas.
  
Bulk-rock geochemical characteristics were analysed by X-ray fluorescence spectrometry where the basalt samples were classified as basanites and ne-hawaiites. The lower and upper basalts have a relatively wide range of major and trace element compositions; whereas, the middle basalt has less variation.

The three basalt lava flows represent pahoehoe and/or transitional lava flows, which occurred during magmatic eruptions separated by periods of volcanic quiescence represented by Quaternary alluvium and/or Kauroa ash deposits. The magma source beneath the Bombay area reveals that it consists of dominantly a garnet-bearing peridotite source where only group B type lavas were erupted over time. This process indicates a polygenetic-like eruption history within a monogenetic field, which may be an ideal analogue for understanding the future of shield volcanism in the South Auckland and Auckland Volcanic Field.

text: Volcanology of the basaltic lava succession within the Auckland pit of the Bombay Quarry, Bombay Volcanic Complex, South Auckland Volcanic Field The South Auckland Volcanic Field (SAVF), which was active 1.59 – 0.51 million years ago and comprises around 82 volcanic centres, represents a complete history of a monogenetic field preserved in the geological record. The Auckland pit in the Bombay Quarry was recently exposed, revealing an infilled palaeovalley of volcanic and sedimentary deposits possibly associated with the nearby Bombay Volcanic Complex. A set of vertical drill cores from across the quarry were available for this study.
 
The stratigraphy of the volcanic and sedimentary deposits and the facies architecture were examined and described from the drill cores available, and a set of stratigraphic logs were produced. Volcanic and sedimentary units identified were: basement Waitemata and Tauranga group sediments, three individual ponded basalt lavas with intercalated scoria and Quaternary alluvium and/or Kauroa ash deposits. Facies identified include: moderately vesicular basalt (A.1), vesicular basalt with vesicle trails (A.2), non-vesicular basalt (A.3), poorly vesicular basalt (A.4), scoria deposit (B), scoriaceous basalt (C) and intercalated silt/clay (D).

Petrographic characteristics were analysed by optical microscopy, which show that all three basalt lavas have minerals comprising: olivine and clinopyroxene phenocrysts, and a groundmass of plagioclase, opaques and mafic minerals, however, the proportions of each mineral vary between samples. Olivine, clinopyroxene and plagioclase elemental compositions for each of the three basalt units were determined by electron microprobe analysis and revealed that the middle basalt had relatively lower proportion of Mg- and Ca-rich minerals compared to the upper and lower basalts. Furthermore, mineral compositions were consistent with the broad group B rock type of the SAVF lavas.
  
Bulk-rock geochemical characteristics were analysed by X-ray fluorescence spectrometry where the basalt samples were classified as basanites and ne-hawaiites. The lower and upper basalts have a relatively wide range of major and trace element compositions; whereas, the middle basalt has less variation.

The three basalt lava flows represent pahoehoe and/or transitional lava flows, which occurred during magmatic eruptions separated by periods of volcanic quiescence represented by Quaternary alluvium and/or Kauroa ash deposits. The magma source beneath the Bombay area reveals that it consists of dominantly a garnet-bearing peridotite source where only group B type lavas were erupted over time. This process indicates a polygenetic-like eruption history within a monogenetic field, which may be an ideal analogue for understanding the future of shield volcanism in the South Auckland and Auckland Volcanic Field.

year: 2016

title: Approaches to benefit sharing

authors: Sterling, Rogena

abstract: This information sheet provides successful examples of different approaches to benefit sharing across a range of industries, from around the world and within Aotearoa. It highlights what works and where challenges and gaps exist in current approaches. Finally, a spectrum of Indigenous sharing approaches is provided, based on the OECD framework of benefit sharing and type of benefit (direct and collective) to Indigenous peoples.

text: Approaches to benefit sharing This information sheet provides successful examples of different approaches to benefit sharing across a range of industries, from around the world and within Aotearoa. It highlights what works and where challenges and gaps exist in current approaches. Finally, a spectrum of Indigenous sharing approaches is provided, based on the OECD framework of benefit sharing and type of benefit (direct and collective) to Indigenous peoples.

year: 2024-06-01