title: The modification of toheroa habitat by streams on Ripiro Beach

authors: Cope, Jane

abstract: Habitat modification and loss are key factors driving the global extinction and displacement of species. The scale and consequences of habitat loss are relatively well understood in terrestrial environments, but in marine ecosystems, and particularly soft sediment ecosystems, this is not the case. The characteristics which determine the suitability of soft sediment habitats are often subtle, due to the apparent homogeneity of sandy environments. This can make it difficult to detect habitat change in the first place let alone understand ecological consequences. Subtle differences in habitat quality are even harder to detect on dynamic surf beaches which are controlled by the interactions between the wave climate and the beach sands, and experience frequent and large changes. The exposed surf beaches of northern New Zealand, are home to toheroa (Paphies ventricosa), an endemic surf clam and New Zealand‘s most protected shell fish species. Over the course of the 20th century, toheroa were harvested to the point of collapse resulting in the closure of an important cultural, recreational and commercial fishery. Despite more than 40 years of protection, toheroa populations have failed to recover with populations in most locations continuing to decline. 

In northern New Zealand toheroa distribution is strongly associated with the small streams which flow across the toheroa beaches. A reduction in the flow of fresh water to the beach via these streams has been suggested as one possible factor which may be preventing the recovery of toheroa. However, little is known about the characteristics of the habitat, and the mechanism driving this toheroa-stream relationship has not received specific attention. The objective of this research was to better understand the effect of streams on beach habitat in the hope of determining the drivers of toheroa distribution. Specifically, I investigated how sediment type, topography, water table depth and sediment temperatures varied across exposed intertidal sediments adjacent to and away from streams. Sampling took place at four sites along Ripiro Beach during the summer, the season when toheroa are most susceptible to thermal stress and streams are thought to provide some protection from dissipation and heat stress. Grainsize distributions from the sampled sediment cores were processed using a Malvern Mastersizer 3000 laser diffractometer (Malvern, UK). The surface elevation and sediment temperature profiles of the subaerial beach was measured using a theodolite CDN pro accurate waterproof thermometers (Model DTW450L). Temperatures were measured at five sediment depths (2cm, 4cm, 7.5cm, 10.5cm, 20.5cm) throughout the sampling period. 

The effect of the streams on the grain size distribution of intertidal sediments appeared to be limited to the high tide, where the proportion of fine sediments was highest in stream adjacent sediments. Greater variations in grain size occurred along the beach, but the greatest difference in sediment sizes occurred when contrasting current day beach grain size distributions with sediment data collected in 1974. Beach sediments from 2017 contained 26661% time more medium sediment indicating the beach is now much coaster than it was 44 years ago. However, as no time series is available for sediment composition at Ripiro it is uncertain whether this change in beach make up is indicative of year-to-year variation or a long term trend. Beach topography varied consistently in the vicinity of streams. The elevation and slope of the beach face was lowest in the path of streams. Along the upper beach, low elevation in the path of the stream lead to the formation of deep bowl like features. As a result of this topography, adjacent to the stream, the water table remained close to the sediment surface throughout the sampling period (< 20 cm), in contrast to point‘s away from the stream where the water table was below the sampling depth. 

The hypothesis that streams would provide a thermal refuge for toheroa was one of the key questions of this thesis. What I found was that stream driven difference in sediment temperatures were only apparent in the upper intestinal, the area occupied by juvenile toheroa when they first recruit to the beach. Temperatures away from streams were significantly higher (> 3.5 °C) than stream adjacent sediments. However, in the middle intestinal, the area occupied by adult toheroa, the seep face exerted a greater influence on sediment temperatures than the stream and temperatures were no different regardless of stream proximity. The findings of this study suggest that the toheroa-stream relationship is not a direct response to the presence of freshwater, but rather is driven by the modification of the intertidal sediments by the streams. The increased erosion in these areas reduces the distance between the sediment surface and the water table, increasing the moisture content of the sediments. Additionally, the formation of the basin like depressions in the upper intertidal may act to aggregate spat and juvenile toheroa through the effect of this topography on the beach swash regime. At mid-tide areas adjacent to streams, the depth of the water table was such that adult toheroa are likely to be either fully or partially immersed throughout the low tide. Away from streams, the water table is beyond the burrowing depth of toheroa. For both juveniles and adults, stream associated areas may provide important protection against desiccation, through increasing moisture content of the sediments and for juveniles through reduced sediment temperatures. 

Evidently, streams do modify beach habitat in a way that makes it inhabitable for toheroa. Just not in the way that was anticipated. This study has increased our knowledge of beach characteristics that provide good toheroa habitat. Further research is required to test these hypotheses and better understand the effects of climate and terrestrial land use on beach state and therefore the suitability of the beach for toheroa.

text: The modification of toheroa habitat by streams on Ripiro Beach Habitat modification and loss are key factors driving the global extinction and displacement of species. The scale and consequences of habitat loss are relatively well understood in terrestrial environments, but in marine ecosystems, and particularly soft sediment ecosystems, this is not the case. The characteristics which determine the suitability of soft sediment habitats are often subtle, due to the apparent homogeneity of sandy environments. This can make it difficult to detect habitat change in the first place let alone understand ecological consequences. Subtle differences in habitat quality are even harder to detect on dynamic surf beaches which are controlled by the interactions between the wave climate and the beach sands, and experience frequent and large changes. The exposed surf beaches of northern New Zealand, are home to toheroa (Paphies ventricosa), an endemic surf clam and New Zealand‘s most protected shell fish species. Over the course of the 20th century, toheroa were harvested to the point of collapse resulting in the closure of an important cultural, recreational and commercial fishery. Despite more than 40 years of protection, toheroa populations have failed to recover with populations in most locations continuing to decline. 

In northern New Zealand toheroa distribution is strongly associated with the small streams which flow across the toheroa beaches. A reduction in the flow of fresh water to the beach via these streams has been suggested as one possible factor which may be preventing the recovery of toheroa. However, little is known about the characteristics of the habitat, and the mechanism driving this toheroa-stream relationship has not received specific attention. The objective of this research was to better understand the effect of streams on beach habitat in the hope of determining the drivers of toheroa distribution. Specifically, I investigated how sediment type, topography, water table depth and sediment temperatures varied across exposed intertidal sediments adjacent to and away from streams. Sampling took place at four sites along Ripiro Beach during the summer, the season when toheroa are most susceptible to thermal stress and streams are thought to provide some protection from dissipation and heat stress. Grainsize distributions from the sampled sediment cores were processed using a Malvern Mastersizer 3000 laser diffractometer (Malvern, UK). The surface elevation and sediment temperature profiles of the subaerial beach was measured using a theodolite CDN pro accurate waterproof thermometers (Model DTW450L). Temperatures were measured at five sediment depths (2cm, 4cm, 7.5cm, 10.5cm, 20.5cm) throughout the sampling period. 

The effect of the streams on the grain size distribution of intertidal sediments appeared to be limited to the high tide, where the proportion of fine sediments was highest in stream adjacent sediments. Greater variations in grain size occurred along the beach, but the greatest difference in sediment sizes occurred when contrasting current day beach grain size distributions with sediment data collected in 1974. Beach sediments from 2017 contained 26661% time more medium sediment indicating the beach is now much coaster than it was 44 years ago. However, as no time series is available for sediment composition at Ripiro it is uncertain whether this change in beach make up is indicative of year-to-year variation or a long term trend. Beach topography varied consistently in the vicinity of streams. The elevation and slope of the beach face was lowest in the path of streams. Along the upper beach, low elevation in the path of the stream lead to the formation of deep bowl like features. As a result of this topography, adjacent to the stream, the water table remained close to the sediment surface throughout the sampling period (< 20 cm), in contrast to point‘s away from the stream where the water table was below the sampling depth. 

The hypothesis that streams would provide a thermal refuge for toheroa was one of the key questions of this thesis. What I found was that stream driven difference in sediment temperatures were only apparent in the upper intestinal, the area occupied by juvenile toheroa when they first recruit to the beach. Temperatures away from streams were significantly higher (> 3.5 °C) than stream adjacent sediments. However, in the middle intestinal, the area occupied by adult toheroa, the seep face exerted a greater influence on sediment temperatures than the stream and temperatures were no different regardless of stream proximity. The findings of this study suggest that the toheroa-stream relationship is not a direct response to the presence of freshwater, but rather is driven by the modification of the intertidal sediments by the streams. The increased erosion in these areas reduces the distance between the sediment surface and the water table, increasing the moisture content of the sediments. Additionally, the formation of the basin like depressions in the upper intertidal may act to aggregate spat and juvenile toheroa through the effect of this topography on the beach swash regime. At mid-tide areas adjacent to streams, the depth of the water table was such that adult toheroa are likely to be either fully or partially immersed throughout the low tide. Away from streams, the water table is beyond the burrowing depth of toheroa. For both juveniles and adults, stream associated areas may provide important protection against desiccation, through increasing moisture content of the sediments and for juveniles through reduced sediment temperatures. 

Evidently, streams do modify beach habitat in a way that makes it inhabitable for toheroa. Just not in the way that was anticipated. This study has increased our knowledge of beach characteristics that provide good toheroa habitat. Further research is required to test these hypotheses and better understand the effects of climate and terrestrial land use on beach state and therefore the suitability of the beach for toheroa.

year: 2018

title: Niupepa: A historical newspaper collection

authors: Apperley, Mark

abstract: Niupepa is a collection of 42 newspaper titles published in New Zealand from 1842-1933, comprising a total of 21,000 pages in 1,750 issues. This collection forms a unique historical record of the language of the indigenous Mãori people, the evolution of the written form of this language, and of events and developments during the formative colonial history of our country. Using the Greenstone software from the New Zealand Digital Library this collection is now publicly available with full-text search capability.

text: Niupepa: A historical newspaper collection Niupepa is a collection of 42 newspaper titles published in New Zealand from 1842-1933, comprising a total of 21,000 pages in 1,750 issues. This collection forms a unique historical record of the language of the indigenous Mãori people, the evolution of the written form of this language, and of events and developments during the formative colonial history of our country. Using the Greenstone software from the New Zealand Digital Library this collection is now publicly available with full-text search capability.

year: 2001-05-01

title: The Effects of a Phonological Awareness and Alphabet Knowledge Intervention on Four Year Old Kindergarten Children

authors: Rachmani, Rachel Margaret

subjects: Phonological awareness

abstract: Phonological awareness and alphabet knowledge are two of the strongest predictors of reading acquisition. Many New Zealand children are entering school with low levels of emergent literacy skills, so an important area of study is how to boost the phonological awareness and alphabet knowledge of four year olds in preparation for their entrance into school. The current research proposed an evidence-based intervention, using games and books, could raise the levels of phonological awareness and alphabet knowledge in children who were shown to have low levels of emergent literacy. The study examined the variation of emergent literacy knowledge, assessed using PALS Pre-K, in a sample of 42 New Zealand four year old children attending kindergarten. The study also investigated the effects of a phonological awareness and alphabet knowledge intervention in a sample of 24 four year old children (taken from the original sample of 42). The results showed 1) a large range in the emergent literacy scores of the 42 four year olds and 2) that a phonological awareness and alphabet knowledge intervention was effective in significantly raising the levels of upper-case letter-naming, letter-sound awareness and beginning sound awareness in the intervention group. The scores for name writing, lower-case letter-naming and rhyming although higher for the intervention group were not significantly so. The results suggest there is a relationship between letter-naming knowledge and letter-sound knowledge and that beginning sound knowledge was a difficult concept for many children to grasp without explicit teaching. The findings showed an evidence-based intervention that is designed appropriately with regard to focus, length of session and group size, can be effective in raising the emergent literacy knowledge of a group of four year old children with low levels of emergent literacy knowledge.

text: The Effects of a Phonological Awareness and Alphabet Knowledge Intervention on Four Year Old Kindergarten Children Phonological awareness and alphabet knowledge are two of the strongest predictors of reading acquisition. Many New Zealand children are entering school with low levels of emergent literacy skills, so an important area of study is how to boost the phonological awareness and alphabet knowledge of four year olds in preparation for their entrance into school. The current research proposed an evidence-based intervention, using games and books, could raise the levels of phonological awareness and alphabet knowledge in children who were shown to have low levels of emergent literacy. The study examined the variation of emergent literacy knowledge, assessed using PALS Pre-K, in a sample of 42 New Zealand four year old children attending kindergarten. The study also investigated the effects of a phonological awareness and alphabet knowledge intervention in a sample of 24 four year old children (taken from the original sample of 42). The results showed 1) a large range in the emergent literacy scores of the 42 four year olds and 2) that a phonological awareness and alphabet knowledge intervention was effective in significantly raising the levels of upper-case letter-naming, letter-sound awareness and beginning sound awareness in the intervention group. The scores for name writing, lower-case letter-naming and rhyming although higher for the intervention group were not significantly so. The results suggest there is a relationship between letter-naming knowledge and letter-sound knowledge and that beginning sound knowledge was a difficult concept for many children to grasp without explicit teaching. The findings showed an evidence-based intervention that is designed appropriately with regard to focus, length of session and group size, can be effective in raising the emergent literacy knowledge of a group of four year old children with low levels of emergent literacy knowledge.

year: 2011