title: Variation in benthic primary production during tidal emersion within different intertidal habitats

authors: Rogers, Kate

abstract: Intertidal habitats provide a wealth of ecosystem services including fuelling oceanic food webs and processing nutrients however, understanding the response of these habitats to emersion has been largely overlooked. Increasing rates of terrestrial sediment reaching the coast is degrading the water column light climate and thus the productive capacity of benthic primary producers during immersion. As a result, low tide production may become more significant in the near future. There is currently little knowledge regarding how primary production changes over an emersion period, in particular how it varies with habitat type and the impacts of environmental stressors, such as desiccation.  

This study explored the spatial (between habitats) and temporal (over austral summer and over individual emersion periods) variability in benthic primary production within a temperate barrier-enclosed estuary. Research was conducted in three intertidal habitats (encompassing differences in sediment properties, dominant primary producers, and macrofaunal communities) in Tauranga Harbour, New Zealand. Seagrass (Zostera muelleri), shellfish, and polychaete dominated habitats were chosen as they represent common intertidal habitats found in temperate regions. Emerged gross primary production (GPP), at the community scale, was quantified by measuring changes in carbon dioxide (CO2) concentration over time during a series of successive three minute incubations spanning the entirety of the low tide period. This was achieved by measuring fluxes of CO2 in benthic incubation chambers under both light and dark conditions, to derive net primary production (NPP) and sediment oxygen consumption (SOC) respectively. CO2 fluxes were then analysed to determine whether sampling month or time exposed had a significant difference on the photosynthetic capacity of different intertidal habitats. Sedimentary and environmental variables were sampled to identify any key predictors of emerged primary production. 

Primary production (both NPP and GPP) measured in the seagrass habitat exceeded both bare sediment habitats (by up to 11 times) due to inherent differences in the dominant primary producers (seagrass vs. microphytobenthos) and the associated photosynthetic biomass. Within bare sediment habitats, significant differences in primary production were attributed to variation in sedimentary characteristics (particularly mud content) and macrofaunal communities. GPP was standardised for photosynthesising biomass to provide a measure of photosynthetic efficiency (GPPSG and GPPchl a). Once standardised, month to month differences within individual habitats disappeared, thus initial temporal differences measured over austral summer were primarily attributed to differences in biomass. Temporal trends over individual emersion periods were not consistent across all habitats. GPPSG in the seagrass habitat increased hourly (from T1 to T4) on multiple sampling occasions, while no consistent trends were evident in either of the bare sediment habitats.  

This study recognises that emerged primary production can equal, if not exceed, rates of production and carbon fixation during immersion. This reinforces the importance of including emerged intertidal habitats in global carbon budgets. Especially as the contribution of low tide production will become increasingly important as elevated turbidity levels may compromise the productive capacity of submerged habitats. Understanding the dynamics of intertidal habitats under emersion is valuable as they represent a significant proportion of coastal ecosystems in New Zealand and around the globe.

text: Variation in benthic primary production during tidal emersion within different intertidal habitats Intertidal habitats provide a wealth of ecosystem services including fuelling oceanic food webs and processing nutrients however, understanding the response of these habitats to emersion has been largely overlooked. Increasing rates of terrestrial sediment reaching the coast is degrading the water column light climate and thus the productive capacity of benthic primary producers during immersion. As a result, low tide production may become more significant in the near future. There is currently little knowledge regarding how primary production changes over an emersion period, in particular how it varies with habitat type and the impacts of environmental stressors, such as desiccation.  

This study explored the spatial (between habitats) and temporal (over austral summer and over individual emersion periods) variability in benthic primary production within a temperate barrier-enclosed estuary. Research was conducted in three intertidal habitats (encompassing differences in sediment properties, dominant primary producers, and macrofaunal communities) in Tauranga Harbour, New Zealand. Seagrass (Zostera muelleri), shellfish, and polychaete dominated habitats were chosen as they represent common intertidal habitats found in temperate regions. Emerged gross primary production (GPP), at the community scale, was quantified by measuring changes in carbon dioxide (CO2) concentration over time during a series of successive three minute incubations spanning the entirety of the low tide period. This was achieved by measuring fluxes of CO2 in benthic incubation chambers under both light and dark conditions, to derive net primary production (NPP) and sediment oxygen consumption (SOC) respectively. CO2 fluxes were then analysed to determine whether sampling month or time exposed had a significant difference on the photosynthetic capacity of different intertidal habitats. Sedimentary and environmental variables were sampled to identify any key predictors of emerged primary production. 

Primary production (both NPP and GPP) measured in the seagrass habitat exceeded both bare sediment habitats (by up to 11 times) due to inherent differences in the dominant primary producers (seagrass vs. microphytobenthos) and the associated photosynthetic biomass. Within bare sediment habitats, significant differences in primary production were attributed to variation in sedimentary characteristics (particularly mud content) and macrofaunal communities. GPP was standardised for photosynthesising biomass to provide a measure of photosynthetic efficiency (GPPSG and GPPchl a). Once standardised, month to month differences within individual habitats disappeared, thus initial temporal differences measured over austral summer were primarily attributed to differences in biomass. Temporal trends over individual emersion periods were not consistent across all habitats. GPPSG in the seagrass habitat increased hourly (from T1 to T4) on multiple sampling occasions, while no consistent trends were evident in either of the bare sediment habitats.  

This study recognises that emerged primary production can equal, if not exceed, rates of production and carbon fixation during immersion. This reinforces the importance of including emerged intertidal habitats in global carbon budgets. Especially as the contribution of low tide production will become increasingly important as elevated turbidity levels may compromise the productive capacity of submerged habitats. Understanding the dynamics of intertidal habitats under emersion is valuable as they represent a significant proportion of coastal ecosystems in New Zealand and around the globe.

year: 2019

title: Aerial conflicts: Drone regulation and gaps in spatial protection

authors: Wallace, Philippa Jane

subjects: Drones

abstract: Drones have undoubtedly arrived in New Zealand landscapes, but less apparent is that adequate regulatory responses have accompanied them. The purpose of this article is to examine the adequacy of New Zealand law and policy in managing the adverse environmental effects of Remotely Piloted Aircraft (RPA).  Currently regulated by the Civil Aviation Act 1990 (CAA 1990) and associated aviation rules, it is argued that this approach fails to sufficiently capture all potential adverse effects. As a result of exemptions for overflying aircraft the Resource Management Act 1991(RMA), the principal legislation governing resource use in the New Zealand environment, is unable to fill the breach. Instead, the CAA 1990 framework applies, rendering an inconsistent regulatory approach exacerbated by rules which rest operational control largely in the hands of property owners. In this manner opportunity to comprehensively manage spatial conflicts is reduced and spatial protection from potential effects is compromised. A better approach is to include RPA operations within the ambit of the RMA, enabling a permissive regime with appropriate controls to manage potential land use/spatial conflicts.

text: Aerial conflicts: Drone regulation and gaps in spatial protection Drones have undoubtedly arrived in New Zealand landscapes, but less apparent is that adequate regulatory responses have accompanied them. The purpose of this article is to examine the adequacy of New Zealand law and policy in managing the adverse environmental effects of Remotely Piloted Aircraft (RPA).  Currently regulated by the Civil Aviation Act 1990 (CAA 1990) and associated aviation rules, it is argued that this approach fails to sufficiently capture all potential adverse effects. As a result of exemptions for overflying aircraft the Resource Management Act 1991(RMA), the principal legislation governing resource use in the New Zealand environment, is unable to fill the breach. Instead, the CAA 1990 framework applies, rendering an inconsistent regulatory approach exacerbated by rules which rest operational control largely in the hands of property owners. In this manner opportunity to comprehensively manage spatial conflicts is reduced and spatial protection from potential effects is compromised. A better approach is to include RPA operations within the ambit of the RMA, enabling a permissive regime with appropriate controls to manage potential land use/spatial conflicts.

year: 2016

title: Editorial: Culturally responsive research and pedagogy

authors: Kostogriz, Alex

abstract: This special and extra issue of English Teaching: Practice and Critique had its origins in an international symposium held in the Faculty of Education at the University of Waikato in November, 2010. The Faculty had already established a tradition of hosting conferences on the theme of language, education and diversity, which had been organised in 2003 and 2007 with input from the Departments of Arts and Language Education, Applied Linguistics and representatives from tainui iwi, and in recognition of the University of Waikato’s strengths in respect of bicultural and multicultural education. In 2010, the thematic focus shifted from a specific focus on language to a broader.

text: Editorial: Culturally responsive research and pedagogy This special and extra issue of English Teaching: Practice and Critique had its origins in an international symposium held in the Faculty of Education at the University of Waikato in November, 2010. The Faculty had already established a tradition of hosting conferences on the theme of language, education and diversity, which had been organised in 2003 and 2007 with input from the Departments of Arts and Language Education, Applied Linguistics and representatives from tainui iwi, and in recognition of the University of Waikato’s strengths in respect of bicultural and multicultural education. In 2010, the thematic focus shifted from a specific focus on language to a broader.

year: 2011