title: Testing the effectiveness of the mt DNA Cytochrome c oxidase subunit 1 (COI) gene locus for identifying species of Polychaete worm (Polychaeta: Annelida) in New Zealand

authors: Brett, Christy Donna

subjects: mt DNA

abstract: The ability to accurately identify species is fundamental to ecological research and environmental monitoring. Current taxonomic identifications often rely on differentiation of morphologically ambiguous characters, and a process of categorization which is tedious and often leads to misidentifications. This is compounded by the presence of cryptic taxa, which may be prevalent among Polychaete worms (Polychaeta: Annelida). With increased access to genetic techniques, Cytochrome c oxidase subunit I has been suggested as a possible aid to assist in the discrimination of species resources.
In this study, I tested the hypothesis that the mtDNA COI gene locus is effective in discriminating morphologically recognised species of Polychaete worms.
A 543 base-pair fragment of the COI locus was successfully extracted for 111 individuals from 16 out of 20 morphologically recognised species. Average intraspecific divergences were 0.8 %, ranging from 0 % to 5 %. Average interspecific variation was 26.4 %, ranging from 13.8 % to 36.8 %. The lowest divergences were found between two Nereid species (13.8 %), and two Glycera americana species (17.2 %). Relatively high maximum divergences of over 30 % suggest that some species may have reached a divergence saturation level, which may partially explain why familial groupings in constructed trees were not monophyletic. Divergences within the different Nereid species - a group previously known to have morphologically cryptic species - did not reveal the presence of any cryptic taxa. Pairwise comparisons showed a clear divide between percentages of intra- and interspecific divergences, and the suggested threshold of 11 % is effective for the taxa investigated here.
On the basis of these results, I conclude that sequence variation in the mtDNA COI gene locus is effective in discriminating morphologically recognised species of Polychaete worms, but may not be appropriate for deeper (e.g. generic or familial) phylogenetic relationships among taxa.

text: Testing the effectiveness of the mt DNA Cytochrome c oxidase subunit 1 (COI) gene locus for identifying species of Polychaete worm (Polychaeta: Annelida) in New Zealand The ability to accurately identify species is fundamental to ecological research and environmental monitoring. Current taxonomic identifications often rely on differentiation of morphologically ambiguous characters, and a process of categorization which is tedious and often leads to misidentifications. This is compounded by the presence of cryptic taxa, which may be prevalent among Polychaete worms (Polychaeta: Annelida). With increased access to genetic techniques, Cytochrome c oxidase subunit I has been suggested as a possible aid to assist in the discrimination of species resources.
In this study, I tested the hypothesis that the mtDNA COI gene locus is effective in discriminating morphologically recognised species of Polychaete worms.
A 543 base-pair fragment of the COI locus was successfully extracted for 111 individuals from 16 out of 20 morphologically recognised species. Average intraspecific divergences were 0.8 %, ranging from 0 % to 5 %. Average interspecific variation was 26.4 %, ranging from 13.8 % to 36.8 %. The lowest divergences were found between two Nereid species (13.8 %), and two Glycera americana species (17.2 %). Relatively high maximum divergences of over 30 % suggest that some species may have reached a divergence saturation level, which may partially explain why familial groupings in constructed trees were not monophyletic. Divergences within the different Nereid species - a group previously known to have morphologically cryptic species - did not reveal the presence of any cryptic taxa. Pairwise comparisons showed a clear divide between percentages of intra- and interspecific divergences, and the suggested threshold of 11 % is effective for the taxa investigated here.
On the basis of these results, I conclude that sequence variation in the mtDNA COI gene locus is effective in discriminating morphologically recognised species of Polychaete worms, but may not be appropriate for deeper (e.g. generic or familial) phylogenetic relationships among taxa.

year: 2006

title: Bio-composites materials from engineered natural fibres for structural applications

authors: Mohd Ghazali, Aruan Efendy

subjects: Aligned discontinuous natural fibre composites

abstract: The large environmental footprint caused by conventional synthetic fibre reinforced petrochemical-derived polymer composites along with potential improvement in mechanical properties for natural fibre reinforced bio-derived polymer composites, have long been a motivation for further research and innovation in natural fibre composites. Harakeke and hemp fibres, amongst other natural fibres, possess respectable mechanical properties along with other advantages such as low cost, low production energy requirements and abundant availability. Polylactic acid (PLA), a sustainable alternative to petrochemical-derived polymers, is produced on a mass scale from 100% renewable resources and can be degraded at end of life by simple hydrolysis under the appropriate conditions. It has high stiffness, strength, thermal and UV stability, but is low in toughness. Limited applications of natural fibre reinforced PLA composites so far is mainly due to low mechanical properties of discontinuous fibre composites made using injection moulding or compression moulding using randomly oriented fibre mats attributed to poor fibre orientation and fibre-matrix incompatibility. Presented in this study are experimental investigations of the properties of PLA reinforced aligned discontinuous harakeke and hemp fibre mats produced using a dynamic sheet former (DSF) to provide improved performance of discontinuous fibre composites.

Harakeke and hemp fibres were treated using either a solution of 5 wt% or 10 wt% NaOH or combination of 5 wt% NaOH with 2 wt% Na2SO3 at elevated temperatures in a small pressure vessel. Treated fibres were assessed using single fibre tensile testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It was found that 5 wt% NaOH/2 wt% Na2SO3 and 5 wt% NaOH effectively removed non-cellulosic materials from harakeke and hemp fibre surfaces, respectively, giving good fibre separation without greatly reducing the tensile strength of the fibres. It was also found that these treatments lead to a higher crystallinity index and improved thermal stability of fibres.

Fibre alignment in fibre mats produced using a DSF was observed using light microscopy. Visual observation supported that the fibre alignment had occurred. Fibre orientation factors (Kɵ) determined for harakeke and hemp composites using the Bowyer-Bader model were found higher compared to Kɵ values obtained for other natural composites prepared using injection and compression moulding. Improved fibre orientation resulted in improved reinforcement giving large increases for tensile strengths up to approximately 90 and 60% for harakeke and hemp composites reinforced with inclusion of 30 and 25 wt% fibre respectively. 

The effect of silane and peroxide as additional fibre treatments and MA-g-PLA as a coupling agent was evaluated by scanning electron microscopy (SEM), composite swelling analysis, tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Scanning electron micrographs of fractured composite surfaces revealed that the gaps between fibres and matrix for composites with fibres treated using silane and peroxide and composites coupled with MA-g-PLA were smaller compared to the surfaces for composites with fibres treated using just alkali. Improved interfacial strength was also supported by lower swelling indices, lower peaks on tan δ and higher residual composites weights, compared to those values obtained for composites with fibres treated using just alkali, which was found to lead to higher composite tensile strengths.

Harakeke and hemp fibre composites were plasticised using hyper-branched polymer (HBP) and assessed using SEM, tensile and impact testing. SEM micrographs for plasticised composites revealed longer pultruding fibres than un-plasticised composites, with gaps between the fibre and matrix appearing to be slightly larger, indicating a weaker interface between fibres and matrix compared to those composites without plasticiser. Improved composite ductility and impact strength were demonstrated for plasticised composites without dramatic reduction of composite tensile strength.

text: Bio-composites materials from engineered natural fibres for structural applications The large environmental footprint caused by conventional synthetic fibre reinforced petrochemical-derived polymer composites along with potential improvement in mechanical properties for natural fibre reinforced bio-derived polymer composites, have long been a motivation for further research and innovation in natural fibre composites. Harakeke and hemp fibres, amongst other natural fibres, possess respectable mechanical properties along with other advantages such as low cost, low production energy requirements and abundant availability. Polylactic acid (PLA), a sustainable alternative to petrochemical-derived polymers, is produced on a mass scale from 100% renewable resources and can be degraded at end of life by simple hydrolysis under the appropriate conditions. It has high stiffness, strength, thermal and UV stability, but is low in toughness. Limited applications of natural fibre reinforced PLA composites so far is mainly due to low mechanical properties of discontinuous fibre composites made using injection moulding or compression moulding using randomly oriented fibre mats attributed to poor fibre orientation and fibre-matrix incompatibility. Presented in this study are experimental investigations of the properties of PLA reinforced aligned discontinuous harakeke and hemp fibre mats produced using a dynamic sheet former (DSF) to provide improved performance of discontinuous fibre composites.

Harakeke and hemp fibres were treated using either a solution of 5 wt% or 10 wt% NaOH or combination of 5 wt% NaOH with 2 wt% Na2SO3 at elevated temperatures in a small pressure vessel. Treated fibres were assessed using single fibre tensile testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It was found that 5 wt% NaOH/2 wt% Na2SO3 and 5 wt% NaOH effectively removed non-cellulosic materials from harakeke and hemp fibre surfaces, respectively, giving good fibre separation without greatly reducing the tensile strength of the fibres. It was also found that these treatments lead to a higher crystallinity index and improved thermal stability of fibres.

Fibre alignment in fibre mats produced using a DSF was observed using light microscopy. Visual observation supported that the fibre alignment had occurred. Fibre orientation factors (Kɵ) determined for harakeke and hemp composites using the Bowyer-Bader model were found higher compared to Kɵ values obtained for other natural composites prepared using injection and compression moulding. Improved fibre orientation resulted in improved reinforcement giving large increases for tensile strengths up to approximately 90 and 60% for harakeke and hemp composites reinforced with inclusion of 30 and 25 wt% fibre respectively. 

The effect of silane and peroxide as additional fibre treatments and MA-g-PLA as a coupling agent was evaluated by scanning electron microscopy (SEM), composite swelling analysis, tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Scanning electron micrographs of fractured composite surfaces revealed that the gaps between fibres and matrix for composites with fibres treated using silane and peroxide and composites coupled with MA-g-PLA were smaller compared to the surfaces for composites with fibres treated using just alkali. Improved interfacial strength was also supported by lower swelling indices, lower peaks on tan δ and higher residual composites weights, compared to those values obtained for composites with fibres treated using just alkali, which was found to lead to higher composite tensile strengths.

Harakeke and hemp fibre composites were plasticised using hyper-branched polymer (HBP) and assessed using SEM, tensile and impact testing. SEM micrographs for plasticised composites revealed longer pultruding fibres than un-plasticised composites, with gaps between the fibre and matrix appearing to be slightly larger, indicating a weaker interface between fibres and matrix compared to those composites without plasticiser. Improved composite ductility and impact strength were demonstrated for plasticised composites without dramatic reduction of composite tensile strength.

year: 2016

title: The relationship between on-water performance and physical characteristics in elite and sub-elite outrigger canoe paddlers

authors: King, Tupuria

abstract: Objectives: The aim of the present study was to compare and investigate the relationship between 500 m on-water performance and physical characteristics in elite and sub-elite outrigger canoe paddlers. Methods: A total of 16 males participated in the study including eight elite paddlers (age: 24.8 ± 10.5 yrs., total paddling experience: 12.5 ± 5.2 yrs.) and eight sub-elite paddlers (age: 34.4 ± 15.4 yrs., total paddling experience: 6.8 ± 5.2 yrs.). Body mass, height, sitting height, arm span, arm length, body fat percentage, 50 kg muscular endurance (bench press and bench pull), peak oxygen uptake (VO2peak) and Wingate performance (30 sec maximal effort) were assessed and subsequently correlated with 500 m outrigger canoeing performance at a national championship’s regatta. Results: When group data were combined, moderate to strong correlations were found between 500 m outrigger canoeing performance and absolute VO2peak (r = -0.61), upper limb length (r = -0.60) 50 kg bench press (r = -0.56), total paddling experience (r = -0.53), body mass (r = -0.51), sitting height (r = -0.51), singles paddling experience (r = -0.49), height (r = -0.48) and Wingate distance (r = -0.42). When groups were compared, elite paddlers showed significantly greater Wingate mean power and distance, paddling experience and 500 m on-water performance times than sub-elite paddlers (p < 0.05). However, there were no significant differences in anthropometrical measures, muscular endurance and VO2peak between the two groups (p < 0.05). Conclusion: VO2peak and upper limb length were the best predictors of performance over the 500 m sprint distance across the entire group. Thirty-second Wingate mean power and distance, years of paddling experience and subsequent 500 m on-water performance differentiated elite from sub-elite paddlers.

text: The relationship between on-water performance and physical characteristics in elite and sub-elite outrigger canoe paddlers Objectives: The aim of the present study was to compare and investigate the relationship between 500 m on-water performance and physical characteristics in elite and sub-elite outrigger canoe paddlers. Methods: A total of 16 males participated in the study including eight elite paddlers (age: 24.8 ± 10.5 yrs., total paddling experience: 12.5 ± 5.2 yrs.) and eight sub-elite paddlers (age: 34.4 ± 15.4 yrs., total paddling experience: 6.8 ± 5.2 yrs.). Body mass, height, sitting height, arm span, arm length, body fat percentage, 50 kg muscular endurance (bench press and bench pull), peak oxygen uptake (VO2peak) and Wingate performance (30 sec maximal effort) were assessed and subsequently correlated with 500 m outrigger canoeing performance at a national championship’s regatta. Results: When group data were combined, moderate to strong correlations were found between 500 m outrigger canoeing performance and absolute VO2peak (r = -0.61), upper limb length (r = -0.60) 50 kg bench press (r = -0.56), total paddling experience (r = -0.53), body mass (r = -0.51), sitting height (r = -0.51), singles paddling experience (r = -0.49), height (r = -0.48) and Wingate distance (r = -0.42). When groups were compared, elite paddlers showed significantly greater Wingate mean power and distance, paddling experience and 500 m on-water performance times than sub-elite paddlers (p < 0.05). However, there were no significant differences in anthropometrical measures, muscular endurance and VO2peak between the two groups (p < 0.05). Conclusion: VO2peak and upper limb length were the best predictors of performance over the 500 m sprint distance across the entire group. Thirty-second Wingate mean power and distance, years of paddling experience and subsequent 500 m on-water performance differentiated elite from sub-elite paddlers.

year: 2019