title: Monitoring brown trout (Salmo trutta) eradication in a wildlife sanctuary using environmental DNA

authors: Banks, Jonathan C.

subjects: brown trout

abstract: Restoration of habitats often necessitates the eradication of exotic animals from a specified area. One of the many challenges associated with the removal of introduced animals is determining the distribution and continued presence of individuals in order to efficiently target control operations and minimise any adverse effects associated with removal. We examined the feasibility of using environmental DNA (eDNA) from water samples, relative to more traditional electric fishing, netting and spotlight surveys (i.e., visual observations of the small streams at night), to determine the presence of brown trout. Samples were taken from within the Zealandia Sanctuary near Wellington, New Zealand, before and after treatment with the piscicide rotenone. Using filtration of water samples, we successfully extracted brown trout DNA from water both before and after rotenone treatment. In most cases, DNA presence corresponded to results obtained through netting and spotlight surveys, and in one instance detected the continued presence of trout in a treated stream (which was subsequently confirmed). We conclude that the use of environmental DNA to detect the presence of exotic fish can be a useful tool to assist in the assessment and restoration of aquatic habitats.

text: Monitoring brown trout (Salmo trutta) eradication in a wildlife sanctuary using environmental DNA Restoration of habitats often necessitates the eradication of exotic animals from a specified area. One of the many challenges associated with the removal of introduced animals is determining the distribution and continued presence of individuals in order to efficiently target control operations and minimise any adverse effects associated with removal. We examined the feasibility of using environmental DNA (eDNA) from water samples, relative to more traditional electric fishing, netting and spotlight surveys (i.e., visual observations of the small streams at night), to determine the presence of brown trout. Samples were taken from within the Zealandia Sanctuary near Wellington, New Zealand, before and after treatment with the piscicide rotenone. Using filtration of water samples, we successfully extracted brown trout DNA from water both before and after rotenone treatment. In most cases, DNA presence corresponded to results obtained through netting and spotlight surveys, and in one instance detected the continued presence of trout in a treated stream (which was subsequently confirmed). We conclude that the use of environmental DNA to detect the presence of exotic fish can be a useful tool to assist in the assessment and restoration of aquatic habitats.

year: 2016

title: Internal fibre length concentration in a pressure screen

authors: Atkins, Martin John

subjects: pressure screening

abstract: Localised axial consistency profiles within a pressure screen of a Pinus Radiata kraft pulp are reported. Axial Samples were also analysed using a Kajaani FS-200 to obtain fibre length distribution data. Localised consistency in the feed annulus was found to vary considerably and the consistency was found to be less than the feed consistency over some portions of the screen (annular dilution). Changes in consistency along the accept side was fairly constant although subtle changes were observed. 
Pulp passage ratios for both the bulk and individual fibre length fractions were calculated using the consistency profiles and fibre length data. In all cases fibre passage decreased along the screen length. Fibre passage was affected by a position effect which is comprised of two factors: flocculation effects, and flow and rotor effects. Fibre fractionation efficiency was found to increase along the length of the screen. 
Mechanisms that account for the observed annular dilution, passage ratio and efficiency changes are proposed. These involve flow of both fluid and fibre in the forward and reverse directions across the screen plate, increased flocculation in the feed annulus and the slip velocity between incoming pulp and the rotor tip.

text: Internal fibre length concentration in a pressure screen Localised axial consistency profiles within a pressure screen of a Pinus Radiata kraft pulp are reported. Axial Samples were also analysed using a Kajaani FS-200 to obtain fibre length distribution data. Localised consistency in the feed annulus was found to vary considerably and the consistency was found to be less than the feed consistency over some portions of the screen (annular dilution). Changes in consistency along the accept side was fairly constant although subtle changes were observed. 
Pulp passage ratios for both the bulk and individual fibre length fractions were calculated using the consistency profiles and fibre length data. In all cases fibre passage decreased along the screen length. Fibre passage was affected by a position effect which is comprised of two factors: flocculation effects, and flow and rotor effects. Fibre fractionation efficiency was found to increase along the length of the screen. 
Mechanisms that account for the observed annular dilution, passage ratio and efficiency changes are proposed. These involve flow of both fluid and fibre in the forward and reverse directions across the screen plate, increased flocculation in the feed annulus and the slip velocity between incoming pulp and the rotor tip.

year: 2007

title: Development and care of pā harakeke in 19th century New Zealand: Voices from the past

authors: McAllum, Priscilla M

subjects: Raranga

abstract: Māori weaving is experiencing a resurgence. Some weavers are involved in the planting of pā harakeke so that they have a high quality resource on hand ready for use.  A number of recent scientific publications, undertaken jointly with weavers, have explored the unique fibre qualities of different harakeke varieties along with specific aspects of Māori use of these varieties. In this paper, I examine Māori planting practices of pā harakeke and other aspects of resource management as revealed in literature sources from the late 18th to the early 20th centuries.  Although some of the practices outlined here may have fallen into disuse over time, they may, nevertheless, continue to be appropriate for contemporary pā harakeke. It is hoped, therefore, that the information provided here will be of interest to contemporary weavers.

text: Development and care of pā harakeke in 19th century New Zealand: Voices from the past Māori weaving is experiencing a resurgence. Some weavers are involved in the planting of pā harakeke so that they have a high quality resource on hand ready for use.  A number of recent scientific publications, undertaken jointly with weavers, have explored the unique fibre qualities of different harakeke varieties along with specific aspects of Māori use of these varieties. In this paper, I examine Māori planting practices of pā harakeke and other aspects of resource management as revealed in literature sources from the late 18th to the early 20th centuries.  Although some of the practices outlined here may have fallen into disuse over time, they may, nevertheless, continue to be appropriate for contemporary pā harakeke. It is hoped, therefore, that the information provided here will be of interest to contemporary weavers.

year: 2005-02