title: Consequences of shellfish die-offs on seafloor biodiversity

authors: Crosbie, Caleb

abstract: Coastal soft sediment habitats contain highly productive benthic communities that provide numerous ecological services. Many of these functions, processes and services are underpinned by the behaviour, density and diversity of the resident macrofaunal community. Climate change has caused heat waves to become more regular and extreme, causing die-off’s of functionally important shellfish beds, potentially generating large shifts in benthic community structure and functioning. Recent studies of the New Zealand intertidal cockle (Austrovenus stutchburyi) dieoff events have focused on cockle population recovery, but there is very little understanding of how the rest of the macrofaunal community responds. To understand how the macrofaunal communities respond to cockle-die offs, a manipulative experiment was undertaken at 23 sites in four estuaries on the northeast coast of the North Island. In late summer, at each site we established a 9m2 control and 9m2 exclusion plot. One year later, we sampled all plots for macrofauna and sediment properties. Results indicate a strong relationship between treatment type and community composition, with none of the exclusion treatments returning to predisturbance community compositions. Furthermore, that recovery was largely estuary specific and community composition following disturbance was highly variable within exclusion treatments. Statistical analysis highlighted that exposure to high intensity wind-wave activity and polychaete dominance within estuaries could explain the relatively improved recovery of Ongare sites within Tauranga harbour. Additionally, there are observable variations in cockle recruitment between sites for both adults and juveniles. This experiment explores whether the removal of cockles, as key habitat forming species, selects for a different macrofaunal community type. The observed changes in community structure can be linked to shifts in ecosystem functioning in these soft sediment habitats.

text: Consequences of shellfish die-offs on seafloor biodiversity Coastal soft sediment habitats contain highly productive benthic communities that provide numerous ecological services. Many of these functions, processes and services are underpinned by the behaviour, density and diversity of the resident macrofaunal community. Climate change has caused heat waves to become more regular and extreme, causing die-off’s of functionally important shellfish beds, potentially generating large shifts in benthic community structure and functioning. Recent studies of the New Zealand intertidal cockle (Austrovenus stutchburyi) dieoff events have focused on cockle population recovery, but there is very little understanding of how the rest of the macrofaunal community responds. To understand how the macrofaunal communities respond to cockle-die offs, a manipulative experiment was undertaken at 23 sites in four estuaries on the northeast coast of the North Island. In late summer, at each site we established a 9m2 control and 9m2 exclusion plot. One year later, we sampled all plots for macrofauna and sediment properties. Results indicate a strong relationship between treatment type and community composition, with none of the exclusion treatments returning to predisturbance community compositions. Furthermore, that recovery was largely estuary specific and community composition following disturbance was highly variable within exclusion treatments. Statistical analysis highlighted that exposure to high intensity wind-wave activity and polychaete dominance within estuaries could explain the relatively improved recovery of Ongare sites within Tauranga harbour. Additionally, there are observable variations in cockle recruitment between sites for both adults and juveniles. This experiment explores whether the removal of cockles, as key habitat forming species, selects for a different macrofaunal community type. The observed changes in community structure can be linked to shifts in ecosystem functioning in these soft sediment habitats.

year: 2024

title: Urban transformative potential in a changing climate

authors: Romero-Lankao, Patricia

abstract: The SDGs and CitiesIPCC offer an unprecedented opportunity for urban transformation, but bold, integrated action to address the constraints imposed by economic, cultural and political dynamics is needed. We move beyond a narrow, technocentric view and identify five key knowledge pathways to catalyse urban transformation.

text: Urban transformative potential in a changing climate The SDGs and CitiesIPCC offer an unprecedented opportunity for urban transformation, but bold, integrated action to address the constraints imposed by economic, cultural and political dynamics is needed. We move beyond a narrow, technocentric view and identify five key knowledge pathways to catalyse urban transformation.

year: 2018

title: Ethnobotany, germination and growth of eleocharis sphacelata

authors: Kapa, Mieke M

subjects: Eleocharis

abstract: Eleocharis sphacelata, distributed over Australia, Papa New Guinea and predominantly in the north of the North Island New Zealand, occupies the littoral margins of fresh water wetlands and lakes. To assist Eleocharis sphacelata revegetation efforts, research recorded traditional ecological knowledge held by users, determined best methodologies for germination of seed, and established techniques for improved transfer of juvenile plantlets. 
Interviews with cultural knowledge holders revealed a declining but persistent oral repository in tikanga (customs) and practices despite diminishing plant availability. Eleocharis sphacelata has traditionally and contemporarily been used as a fibre for weaving into mats, with its spongy pith providing increased warmth and comfort. Group harvesting, with some cutting and others sorting and binding is the first step in a short preparation sequence, with the drying of the stems (for most this is in the shade) the only other preparation needed before weaving commences. Cultural genealogical descriptions provide a clear portrait of the ecological position Eleocharis sphacelata sits within its natural habitat and presents a phylogeny or schemata comparable to biological science. Published information identifies cultural uses and practices for the fibre of this wetland sedge. 
Fresh and stored seeds were subjected to five treatments at three water levels to determine the best methodology for increased germination rates. Findings illustrate how a scarification pre-treatment and water depth increases up to 15 cm enhances germination rates of Eleocharis sphacelata. Overnight bleaching of seed harvested one month earlier (January 2008) then sown under damp conditions provided increased germination until April. Fresh bleached seed sown under 5 cm and 15 cm of water produced significant increases in germination from September. Seasonal timing and variation in water depth as germination triggers indicate dual germination strategies employed by Eleocharis sphacelata.
In November 2007 seed grown seedlings and vegetative propagules were planted in situ under three water depths to establish which plantlet type would provide increased juvenile survival when used in revegetation projects. Findings determined that seed grown seedlings planted under 15 cm of water had the highest survival and produced a greater number of culms per plantlet, however vegetative propagules were better able to survive in damp conditions. Flowering occurred in over 25% of remaining vegetative and seed grown seedlings by the following October indicating the potential for new transfers to be reproducing within one season. 
Further collaborating between Māori and western science would augment and enhance understanding of transferable environmental methodologies. Possible dual germination strategies by the seed were revealed and further research would determine if this replicates the reproductive and growth capabilities of Eleocharis sphacelata and other wetland sedges in their natural environment. Additional seed quality and technological research would increase potential for seed performance. Determining genetic variety within local, regional and national Eleocharis sphacelata swards would establish bounds of local provenance.

text: Ethnobotany, germination and growth of eleocharis sphacelata Eleocharis sphacelata, distributed over Australia, Papa New Guinea and predominantly in the north of the North Island New Zealand, occupies the littoral margins of fresh water wetlands and lakes. To assist Eleocharis sphacelata revegetation efforts, research recorded traditional ecological knowledge held by users, determined best methodologies for germination of seed, and established techniques for improved transfer of juvenile plantlets. 
Interviews with cultural knowledge holders revealed a declining but persistent oral repository in tikanga (customs) and practices despite diminishing plant availability. Eleocharis sphacelata has traditionally and contemporarily been used as a fibre for weaving into mats, with its spongy pith providing increased warmth and comfort. Group harvesting, with some cutting and others sorting and binding is the first step in a short preparation sequence, with the drying of the stems (for most this is in the shade) the only other preparation needed before weaving commences. Cultural genealogical descriptions provide a clear portrait of the ecological position Eleocharis sphacelata sits within its natural habitat and presents a phylogeny or schemata comparable to biological science. Published information identifies cultural uses and practices for the fibre of this wetland sedge. 
Fresh and stored seeds were subjected to five treatments at three water levels to determine the best methodology for increased germination rates. Findings illustrate how a scarification pre-treatment and water depth increases up to 15 cm enhances germination rates of Eleocharis sphacelata. Overnight bleaching of seed harvested one month earlier (January 2008) then sown under damp conditions provided increased germination until April. Fresh bleached seed sown under 5 cm and 15 cm of water produced significant increases in germination from September. Seasonal timing and variation in water depth as germination triggers indicate dual germination strategies employed by Eleocharis sphacelata.
In November 2007 seed grown seedlings and vegetative propagules were planted in situ under three water depths to establish which plantlet type would provide increased juvenile survival when used in revegetation projects. Findings determined that seed grown seedlings planted under 15 cm of water had the highest survival and produced a greater number of culms per plantlet, however vegetative propagules were better able to survive in damp conditions. Flowering occurred in over 25% of remaining vegetative and seed grown seedlings by the following October indicating the potential for new transfers to be reproducing within one season. 
Further collaborating between Māori and western science would augment and enhance understanding of transferable environmental methodologies. Possible dual germination strategies by the seed were revealed and further research would determine if this replicates the reproductive and growth capabilities of Eleocharis sphacelata and other wetland sedges in their natural environment. Additional seed quality and technological research would increase potential for seed performance. Determining genetic variety within local, regional and national Eleocharis sphacelata swards would establish bounds of local provenance.

year: 2009