Little is known of the biology of the parasite Dendrogaster (Crustacea: Ascothoracida), an obligate endoparasite of sea stars. There are some 25 species of Dendrogaster reported worldwide. The highly modified females live within the coelomic cavity of the host, and heterochronous males are parasitic within the mantle cavity of the female. Two sea star species from the Otago Coast were found to be infected with two species of Dendrogaster. These parasite populations were studied from July 1993 to December 1994 to investigate specific aspects of their biology and the interactions between these parasites and their hosts. The parasite found in Allostichaster insignis (Asteridae) was identified as Dendrogaster argentinensis Grygier and Salvat 1984, and Asterodon miliaris (Odontasteridae) was found to contain a previously unknown species, herein described and named Dendrogaster otagoensis n. sp. The structure and function of the mantle of female Dendrogaster sp were determined using light, scanning and transmission electron microscopy. The ultrastructure of the mantle is modified, sharing characteristics found in Rhizocephala (Crustacea: Cirripedia), copepods, and Ulophysema oeresundense (Ascothoracida: Dendrogasteridae), which enable these crustaceans to absorb nutrients. Such modifications include a very thin, crenulated epicuticle, a soft, unscleratinised procuticle, and infoldings of the apical plasma membrane. In Dendrogaster the gut is likely to retain the capacity to absorb nutrients. In general, aspects of infestation of Dendrogaster argentinensis and D. otagoensis are the same. Prevalence of Dendrogaster sp. in Otago sea stars is high and parasitism occurs throughout the year. Seventy-seven point five percent of Asterodon miliaris are infected with D. otagoensis and 97.4% of Allostichaster insignis are infected with D. argentinensis. Up to 144 females are found in a single host, and as many as 34 males in a single female. Mean number of parasites per host changes little over time, but began to decrease in D. argentinensis towards the end of the sample period. The female population is dominated by small individuals, with maximum size likely to depend on space available within the host. Males achieve a large size quickly, but their growth is also restricted by the size of the female they are within. The size and number of females per host are not related to size of the host. Females acquire new males and males grow larger with an increase in female size. Males occur in females of all reproductive stages, but occur with the greatest frequency in brooding females. Reproduction is spread evenly through females in less heavily infected hosts, and there is a reduction in mean size of females as the number of females per host increases, indicative of the crowding effect. Three indices of aggregation show that both sexes of Dendrogaster are highly aggregated in their hosts, with few hosts harbouring most of the parasites. Dendrogaster is a parasitic castrator. Infected hosts have parasite loads ranging from 0.1% - 112% total sea star wet weight. Infected sea stars have smaller pyloric caecae and gonads, however, no gonads were present in uninfected Allostichaster insignis. Effect on the gonads and pyloric caecae increases as parasite load increases. Rather than directly affecting the germinal tissue of the host, Dendrogaster castrates its host indirectly through crowding and/or competitive castration. This castration is variable among hosts in Asterodon miliaris, but is important in Allostichaster insignis. The presence of D. argentinensis in A. insignis is associated with an increase in the incidence of asexual reproduction among larger (R>25mm) individuals. Specific growth rates of intact and regenerating arms in fed and starved A. insignis are lower in infected individuals. Larvae are brooded in the mantle cavity of the female until reaching the infective, swimming ascothoracid II stage. The larval development of Dendrogaster argentinensis and D. otagoensis is abbreviated. Larvae moult directly from the egg into the metanauplius. Metanauplii moult into ascothoracid I stage, which moult into the ascothoracid II stage immediately upon release from the female. Ultrastructure confirms the putative sensory function of the lattice organs. Other larval cuticular structures are also sensory. Histological examination revealed that Dendrogaster has unique system of ovulation among Crustacea. The ovarian membrane contains primary oocytes, early vitellogenic and vitellogenic oocytes, but not maturing oocytes, which are found outside the ovarian membrane. The ovarian membrane forms follicles from which vitellogenic oocytes burst into the surrounding mesodermal tissue. These oocytes mature within the mantle wall tissue until entering the mantle cavity, where they are fertilised. Ovaries are absent in most brooding females. Spermatogenesis takes place within the males posterior protrusions and is continuous. Dendrogaster are likely to be labile hermaphrodites, as sperm are found in 20% of ovaries. Female Dendrogaster display asynchronous reproduction, with females of all sizes at different stages throughout the year. Females within one host are also at different stages. Spermatogenesis is present in males of all sizes. The presence of spent males in some females is indicative of a females outliving the males.

The Greenshell™ mussel (GSM), Perna canaliculus, industry in New Zealand (NZ) is the largest aquaculture sector in the country. In 2006, the export earnings were valued at US$145 million which represented 65% of NZ aquaculture earnings. Historically, and at present, GSM production involves the capture of wild mussels on ropes followed by on-growing of these animals to market size (approximately 14 months). However, hatchery production of GSM has been developed in recent years. Hatchery production will alleviate the seasonal uncertainties of current techniques and allow the benefits of selective breeding programs. To date, efforts to produce commercial quantities of GSM in hatcheries have been hampered by unreliable larval rearing. These problems were often alleviated by antibiotic use, which implied bacterial pathogens as the cause. Yet, the ongoing use of antibiotics is not sustainable because of increasing legislative restrictions on their use and the possible emergence of antibiotic resistant bacteria. Hence, the identification and use of novel probiotics was investigated as an alternative. Because of a lack of previous work, it was necessary to investigate the bacterial pathogenesis of GSM larvae in the initial stages and, hence, to determine the cause of disease against which the probiotics would be active. Twenty-two bacterial strains, isolated from compromised larvae, were screened for larval toxicity using a larval bioassay. Two strains were identified as potential pathogens. Sequencing of the 16S rRNA gene identified Vibrio splendidus and Vibrio sp. DO1, a Vibrio coralliilyticus/neptunius-like isolate, as pathogens of GSM larvae. These strains had the- ability to cause 83 and 75% GSM larval mortality in vitro respectively, at a concentration 102 CFU ml-1. Histopathology indicated the route of infection was via the digestive system. Using healthy larvae as target hosts, Koch's postulates were confirmed for the two isolates. Although two bacterial pathogens were identified, the successful design and implementation of protective measures in the hatchery still required an understanding of the dynamics of the infection process. Developing an in situ experimental model for infection was therefore paramount. The minimum effective pathogenic dose (MEPD) of V. splendidus (105 CFU ml-1) and Vibrio sp. DO1 (106 CFU ml-1) was demonstrated for GSM larvae during hatchery production. In a flow-through water hatchery system, larvae given 1-2 hours of static water exposure with these pathogen doses, after which flowthrough processes resumed, averaged 58% and 69% cumulative mortality, respectively, on the fourth day following pathogen exposure. Larvae exposed to a dosage one order of magnitude greater than the MEPD, had higher mortalities of 73% and 96% for V. splendidus and Vibrio sp. DO1 respectively. These four levels of mortality were significantly greater than those of the non-exposed control larvae, averaging 23% in the experiments involving V. splendidus and 35% with Vibrio sp. DO1. Experiments were repeated four times to establish reproducibility. The infection models were reproducible and provided a tool to assess measures for the protection of GSM larvae against infection in the hatchery environment. A bioassay was developed to screen and select bacterial strains as potential probiotics for GSM larvae. Sixty-nine isolates originating from a GSM hatchery environment were tested for probiotic activity in larval pathogen-challenge bioassays conducted in tissue culture dishes (TCDs). Vibrio sp. DO1 and V. splendidus were the tested pathogens. Forty of the tested isolates afforded larval survival significantly greater than pathogen controls (p < 0.05). The bioassay technique achieved a 58% success rate in searching for putative probiotics and highlighted the benefit of including the host animal in the first stage of the screening procedure. The time of inoculation of putative probiotic strains prior to pathogen challenge influenced the outcome of the assay. A pre-exposure period of 20 hours revealed a greater number of potential probiotics than a two-hour pre-exposure period. Pilot challenge tests, under normal hatchery conditions, confirmed the usefulness of the TCD screening method in recognising effective probiotics. Following hatchery pilot trials, two probiotic strains were chosen for further study, namely strains 0444 and 0536. Sequencing of the 16S rRNA gene and phylogenetic analysis identified the strains as Alteromonas macleodii 0444 and Neptunomonas sp. 0536. Both probiotics were evaluated separately in a GSM hatchery facility during routine larval rearing and when the larvae were challenged with a high and low pathogenic dose of Vibrio sp. DO1 and V. splendidus. In all experiments, probiotic application significantly improved larval survival, if administered prior to pathogen exposure. Across all experiments, larvae that were exposed to the high and low dosages of pathogens averaged 14% and 36% survival respectively on the fourth day following pathogen exposure. If the probiotics were administered prior to pathogen challenge, larval survival averaged 50% and 66% respectively. Non-inoculated control larvae and larvae administered the probiotic alone demonstrated 67% and 79% survival respectively. In a repeat experiment, these benefits were reproduced, with the exception of A. macleodii 0444 trialled against V. splendidus. Neptunomonas sp. 0536 appeared to suppress naturally occurring vibrios in the culture environment of healthy GSM larvae. This was the first time A. macleodii and Neptunomonas sp. were demonstrated as probiotic bacteria. Many studies document probiotic application in aquaculture under conditions of pathogen attack, yet few describe the use of probiotics during routine production. The effects of administering the probiotic, A. macleodii 0444, during routine GSM larvae production, were compared against larvae from the same cohort that were not treated with the probiotic. The probiotic was administered daily for the first 11 days of the larval period and was provided at two concentrations, 107 CFU ml-1 and 108 CFU ml-1. Measures of larval swimming activity, gut colouration, lipid levels, larval survival, larval size and settlement success were recorded. There were minimal differences in all parameters between larvae provided the probiotic and control larvae. Probiotic treated larvae consumed more food and had higher lipid levels at the end of the larval period, but these were not statistically significant. All treatments completed the larval phase and settled successfully after metamorphosis. Survival at the end of the larval period was 37.2%, 38.8%, and 34.8% for control, 107 CFU ml-1 and 108 CFU ml-1 treatments respectively. The probiotic was still detected in larvae seven days after the final addition to the tanks. Animals were further grown in the field at a commercial farm. The probiotic was not detected in mussels at four months after leaving the hatchery. Combination use of the two probiotics, A. macleodii 0444 and Neptunomonas sp. 0536, was investigated to determine whether additive protection against pathogen attack with Vibrio sp. DO1 and V. splendidus was afforded to GSM larvae. The effects of combination administration were compared with larvae administered each probiotic as single strains and non-inoculated larvae. Additionally, two concentrations were tested for each probiotic, both singly and in combination, 107 and 108 CFU ml-1. Larvae were administered probiotics daily for the first six days, challenged with pathogens on the third day and then reared until settlement (day 19). Although protection against pathogen attack was observed in combination treatments, when compared with single-strain administration, additive protection was not apparent. Administration of 108 CFU ml-1 levels of probiotics, both singly and in combination, afforded larval survival slightly better than 107 CFU ml-1 levels, although this was rarely statistically significant. On the other hand, the higher levels of probiotic led to smaller larvae and lower feed rates for the majority of the 19-day trial. At the end of the study, larval sizes were smaller in the treatment applied a combination of probiotics at 108 CFU ml-1 than those of the other treatments. Additionally, towards the end of the larval period, feed consumption in the combination 108 CFU ml-1 treatment was similar to that witnessed in the other probiotic treatments one day previously. This suggested that either the larvae were compromised or they were growing slower. Despite a lack of additive protection against a single strain pathogen attack being demonstrated, the potential benefit of multi-strain probiotics, as prophylactic measures against every-day microbial encounters in larviculture, would remain. Although 108 CFU ml-1 levels appeared to protect against pathogen attack slightly better, they were also potentially detrimental to normal larval rearing when administered in combination. Following the successful completion of the larval period and pathogen protection afforded with a combination of probiotics at 107 CFU ml-1, this level was recommended as the best concentration of each probiotic where combination administration would be applied. The work presented in this thesis supports the use of A. macleodii 0444 and Neptunomonas sp. 0536 in the routine rearing of GSM larvae. The ability to produce settled juvenile mussels, equal in numbers to those produced in normal healthy conditions, plus the benefits against pathogen attack led to the recommendation of their use on a routine prophylactic basis in GSM larval rearing. Their use for this purpose is intended in the near future. A provisional patent has been prepared and will be submitted shortly. It is anticipated that future work will continue with these probiotic strains to determine their potential benefit for other aquaculture species.

The Greenshell™ mussel (GSM), Perna canaliculus, industry in New Zealand (NZ) is the largest aquaculture sector in the country. In 2006, the export earnings were valued at US$145 million which represented 65% of NZ aquaculture earnings. Historically, and at present, GSM production involves the capture of wild mussels on ropes followed by on-growing of these animals to market size (approximately 14 months). However, hatchery production of GSM has been developed in recent years. Hatchery production will alleviate the seasonal uncertainties of current techniques and allow the benefits of selective breeding programs. To date, efforts to produce commercial quantities of GSM in hatcheries have been hampered by unreliable larval rearing. These problems were often alleviated by antibiotic use, which implied bacterial pathogens as the cause. Yet, the ongoing use of antibiotics is not sustainable because of increasing legislative restrictions on their use and the possible emergence of antibiotic resistant bacteria. Hence, the identification and use of novel probiotics was investigated as an alternative. Because of a lack of previous work, it was necessary to investigate the bacterial pathogenesis of GSM larvae in the initial stages and, hence, to determine the cause of disease against which the probiotics would be active. Twenty-two bacterial strains, isolated from compromised larvae, were screened for larval toxicity using a larval bioassay. Two strains were identified as potential pathogens. Sequencing of the 16S rRNA gene identified Vibrio splendidus and Vibrio sp. DO1, a Vibrio coralliilyticus/neptunius-like isolate, as pathogens of GSM larvae. These strains had the- ability to cause 83 and 75% GSM larval mortality in vitro respectively, at a concentration 102 CFU ml-1. Histopathology indicated the route of infection was via the digestive system. Using healthy larvae as target hosts, Koch's postulates were confirmed for the two isolates. Although two bacterial pathogens were identified, the successful design and implementation of protective measures in the hatchery still required an understanding of the dynamics of the infection process. Developing an in situ experimental model for infection was therefore paramount. The minimum effective pathogenic dose (MEPD) of V. splendidus (105 CFU ml-1) and Vibrio sp. DO1 (106 CFU ml-1) was demonstrated for GSM larvae during hatchery production. In a flow-through water hatchery system, larvae given 1-2 hours of static water exposure with these pathogen doses, after which flowthrough processes resumed, averaged 58% and 69% cumulative mortality, respectively, on the fourth day following pathogen exposure. Larvae exposed to a dosage one order of magnitude greater than the MEPD, had higher mortalities of 73% and 96% for V. splendidus and Vibrio sp. DO1 respectively. These four levels of mortality were significantly greater than those of the non-exposed control larvae, averaging 23% in the experiments involving V. splendidus and 35% with Vibrio sp. DO1. Experiments were repeated four times to establish reproducibility. The infection models were reproducible and provided a tool to assess measures for the protection of GSM larvae against infection in the hatchery environment. A bioassay was developed to screen and select bacterial strains as potential probiotics for GSM larvae. Sixty-nine isolates originating from a GSM hatchery environment were tested for probiotic activity in larval pathogen-challenge bioassays conducted in tissue culture dishes (TCDs). Vibrio sp. DO1 and V. splendidus were the tested pathogens. Forty of the tested isolates afforded larval survival significantly greater than pathogen controls (p < 0.05). The bioassay technique achieved a 58% success rate in searching for putative probiotics and highlighted the benefit of including the host animal in the first stage of the screening procedure. The time of inoculation of putative probiotic strains prior to pathogen challenge influenced the outcome of the assay. A pre-exposure period of 20 hours revealed a greater number of potential probiotics than a two-hour pre-exposure period. Pilot challenge tests, under normal hatchery conditions, confirmed the usefulness of the TCD screening method in recognising effective probiotics. Following hatchery pilot trials, two probiotic strains were chosen for further study, namely strains 0444 and 0536. Sequencing of the 16S rRNA gene and phylogenetic analysis identified the strains as Alteromonas macleodii 0444 and Neptunomonas sp. 0536. Both probiotics were evaluated separately in a GSM hatchery facility during routine larval rearing and when the larvae were challenged with a high and low pathogenic dose of Vibrio sp. DO1 and V. splendidus. In all experiments, probiotic application significantly improved larval survival, if administered prior to pathogen exposure. Across all experiments, larvae that were exposed to the high and low dosages of pathogens averaged 14% and 36% survival respectively on the fourth day following pathogen exposure. If the probiotics were administered prior to pathogen challenge, larval survival averaged 50% and 66% respectively. Non-inoculated control larvae and larvae administered the probiotic alone demonstrated 67% and 79% survival respectively. In a repeat experiment, these benefits were reproduced, with the exception of A. macleodii 0444 trialled against V. splendidus. Neptunomonas sp. 0536 appeared to suppress naturally occurring vibrios in the culture environment of healthy GSM larvae. This was the first time A. macleodii and Neptunomonas sp. were demonstrated as probiotic bacteria. Many studies document probiotic application in aquaculture under conditions of pathogen attack, yet few describe the use of probiotics during routine production. The effects of administering the probiotic, A. macleodii 0444, during routine GSM larvae production, were compared against larvae from the same cohort that were not treated with the probiotic. The probiotic was administered daily for the first 11 days of the larval period and was provided at two concentrations, 107 CFU ml-1 and 108 CFU ml-1. Measures of larval swimming activity, gut colouration, lipid levels, larval survival, larval size and settlement success were recorded. There were minimal differences in all parameters between larvae provided the probiotic and control larvae. Probiotic treated larvae consumed more food and had higher lipid levels at the end of the larval period, but these were not statistically significant. All treatments completed the larval phase and settled successfully after metamorphosis. Survival at the end of the larval period was 37.2%, 38.8%, and 34.8% for control, 107 CFU ml-1 and 108 CFU ml-1 treatments respectively. The probiotic was still detected in larvae seven days after the final addition to the tanks. Animals were further grown in the field at a commercial farm. The probiotic was not detected in mussels at four months after leaving the hatchery. Combination use of the two probiotics, A. macleodii 0444 and Neptunomonas sp. 0536, was investigated to determine whether additive protection against pathogen attack with Vibrio sp. DO1 and V. splendidus was afforded to GSM larvae. The effects of combination administration were compared with larvae administered each probiotic as single strains and non-inoculated larvae. Additionally, two concentrations were tested for each probiotic, both singly and in combination, 107 and 108 CFU ml-1. Larvae were administered probiotics daily for the first six days, challenged with pathogens on the third day and then reared until settlement (day 19). Although protection against pathogen attack was observed in combination treatments, when compared with single-strain administration, additive protection was not apparent. Administration of 108 CFU ml-1 levels of probiotics, both singly and in combination, afforded larval survival slightly better than 107 CFU ml-1 levels, although this was rarely statistically significant. On the other hand, the higher levels of probiotic led to smaller larvae and lower feed rates for the majority of the 19-day trial. At the end of the study, larval sizes were smaller in the treatment applied a combination of probiotics at 108 CFU ml-1 than those of the other treatments. Additionally, towards the end of the larval period, feed consumption in the combination 108 CFU ml-1 treatment was similar to that witnessed in the other probiotic treatments one day previously. This suggested that either the larvae were compromised or they were growing slower. Despite a lack of additive protection against a single strain pathogen attack being demonstrated, the potential benefit of multi-strain probiotics, as prophylactic measures against every-day microbial encounters in larviculture, would remain. Although 108 CFU ml-1 levels appeared to protect against pathogen attack slightly better, they were also potentially detrimental to normal larval rearing when administered in combination. Following the successful completion of the larval period and pathogen protection afforded with a combination of probiotics at 107 CFU ml-1, this level was recommended as the best concentration of each probiotic where combination administration would be applied. The work presented in this thesis supports the use of A. macleodii 0444 and Neptunomonas sp. 0536 in the routine rearing of GSM larvae. The ability to produce settled juvenile mussels, equal in numbers to those produced in normal healthy conditions, plus the benefits against pathogen attack led to the recommendation of their use on a routine prophylactic basis in GSM larval rearing. Their use for this purpose is intended in the near future. A provisional patent has been prepared and will be submitted shortly. It is anticipated that future work will continue with these probiotic strains to determine their potential benefit for other aquaculture species.

The Greenshell™ mussel (GSM), Perna canaliculus, industry in New Zealand (NZ) is the largest aquaculture sector in the country. In 2006, the export earnings were valued at US$145 million which represented 65% of NZ aquaculture earnings. Historically, and at present, GSM production involves the capture of wild mussels on ropes followed by on-growing of these animals to market size (approximately 14 months). However, hatchery production of GSM has been developed in recent years. Hatchery production will alleviate the seasonal uncertainties of current techniques and allow the benefits of selective breeding programs. To date, efforts to produce commercial quantities of GSM in hatcheries have been hampered by unreliable larval rearing. These problems were often alleviated by antibiotic use, which implied bacterial pathogens as the cause. Yet, the ongoing use of antibiotics is not sustainable because of increasing legislative restrictions on their use and the possible emergence of antibiotic resistant bacteria. Hence, the identification and use of novel probiotics was investigated as an alternative. Because of a lack of previous work, it was necessary to investigate the bacterial pathogenesis of GSM larvae in the initial stages and, hence, to determine the cause of disease against which the probiotics would be active. Twenty-two bacterial strains, isolated from compromised larvae, were screened for larval toxicity using a larval bioassay. Two strains were identified as potential pathogens. Sequencing of the 16S rRNA gene identified Vibrio splendidus and Vibrio sp. DO1, a Vibrio coralliilyticus/neptunius-like isolate, as pathogens of GSM larvae. These strains had the- ability to cause 83 and 75% GSM larval mortality in vitro respectively, at a concentration 102 CFU ml-1. Histopathology indicated the route of infection was via the digestive system. Using healthy larvae as target hosts, Koch's postulates were confirmed for the two isolates. Although two bacterial pathogens were identified, the successful design and implementation of protective measures in the hatchery still required an understanding of the dynamics of the infection process. Developing an in situ experimental model for infection was therefore paramount. The minimum effective pathogenic dose (MEPD) of V. splendidus (105 CFU ml-1) and Vibrio sp. DO1 (106 CFU ml-1) was demonstrated for GSM larvae during hatchery production. In a flow-through water hatchery system, larvae given 1-2 hours of static water exposure with these pathogen doses, after which flowthrough processes resumed, averaged 58% and 69% cumulative mortality, respectively, on the fourth day following pathogen exposure. Larvae exposed to a dosage one order of magnitude greater than the MEPD, had higher mortalities of 73% and 96% for V. splendidus and Vibrio sp. DO1 respectively. These four levels of mortality were significantly greater than those of the non-exposed control larvae, averaging 23% in the experiments involving V. splendidus and 35% with Vibrio sp. DO1. Experiments were repeated four times to establish reproducibility. The infection models were reproducible and provided a tool to assess measures for the protection of GSM larvae against infection in the hatchery environment. A bioassay was developed to screen and select bacterial strains as potential probiotics for GSM larvae. Sixty-nine isolates originating from a GSM hatchery environment were tested for probiotic activity in larval pathogen-challenge bioassays conducted in tissue culture dishes (TCDs). Vibrio sp. DO1 and V. splendidus were the tested pathogens. Forty of the tested isolates afforded larval survival significantly greater than pathogen controls (p < 0.05). The bioassay technique achieved a 58% success rate in searching for putative probiotics and highlighted the benefit of including the host animal in the first stage of the screening procedure. The time of inoculation of putative probiotic strains prior to pathogen challenge influenced the outcome of the assay. A pre-exposure period of 20 hours revealed a greater number of potential probiotics than a two-hour pre-exposure period. Pilot challenge tests, under normal hatchery conditions, confirmed the usefulness of the TCD screening method in recognising effective probiotics. Following hatchery pilot trials, two probiotic strains were chosen for further study, namely strains 0444 and 0536. Sequencing of the 16S rRNA gene and phylogenetic analysis identified the strains as Alteromonas macleodii 0444 and Neptunomonas sp. 0536. Both probiotics were evaluated separately in a GSM hatchery facility during routine larval rearing and when the larvae were challenged with a high and low pathogenic dose of Vibrio sp. DO1 and V. splendidus. In all experiments, probiotic application significantly improved larval survival, if administered prior to pathogen exposure. Across all experiments, larvae that were exposed to the high and low dosages of pathogens averaged 14% and 36% survival respectively on the fourth day following pathogen exposure. If the probiotics were administered prior to pathogen challenge, larval survival averaged 50% and 66% respectively. Non-inoculated control larvae and larvae administered the probiotic alone demonstrated 67% and 79% survival respectively. In a repeat experiment, these benefits were reproduced, with the exception of A. macleodii 0444 trialled against V. splendidus. Neptunomonas sp. 0536 appeared to suppress naturally occurring vibrios in the culture environment of healthy GSM larvae. This was the first time A. macleodii and Neptunomonas sp. were demonstrated as probiotic bacteria. Many studies document probiotic application in aquaculture under conditions of pathogen attack, yet few describe the use of probiotics during routine production. The effects of administering the probiotic, A. macleodii 0444, during routine GSM larvae production, were compared against larvae from the same cohort that were not treated with the probiotic. The probiotic was administered daily for the first 11 days of the larval period and was provided at two concentrations, 107 CFU ml-1 and 108 CFU ml-1. Measures of larval swimming activity, gut colouration, lipid levels, larval survival, larval size and settlement success were recorded. There were minimal differences in all parameters between larvae provided the probiotic and control larvae. Probiotic treated larvae consumed more food and had higher lipid levels at the end of the larval period, but these were not statistically significant. All treatments completed the larval phase and settled successfully after metamorphosis. Survival at the end of the larval period was 37.2%, 38.8%, and 34.8% for control, 107 CFU ml-1 and 108 CFU ml-1 treatments respectively. The probiotic was still detected in larvae seven days after the final addition to the tanks. Animals were further grown in the field at a commercial farm. The probiotic was not detected in mussels at four months after leaving the hatchery. Combination use of the two probiotics, A. macleodii 0444 and Neptunomonas sp. 0536, was investigated to determine whether additive protection against pathogen attack with Vibrio sp. DO1 and V. splendidus was afforded to GSM larvae. The effects of combination administration were compared with larvae administered each probiotic as single strains and non-inoculated larvae. Additionally, two concentrations were tested for each probiotic, both singly and in combination, 107 and 108 CFU ml-1. Larvae were administered probiotics daily for the first six days, challenged with pathogens on the third day and then reared until settlement (day 19). Although protection against pathogen attack was observed in combination treatments, when compared with single-strain administration, additive protection was not apparent. Administration of 108 CFU ml-1 levels of probiotics, both singly and in combination, afforded larval survival slightly better than 107 CFU ml-1 levels, although this was rarely statistically significant. On the other hand, the higher levels of probiotic led to smaller larvae and lower feed rates for the majority of the 19-day trial. At the end of the study, larval sizes were smaller in the treatment applied a combination of probiotics at 108 CFU ml-1 than those of the other treatments. Additionally, towards the end of the larval period, feed consumption in the combination 108 CFU ml-1 treatment was similar to that witnessed in the other probiotic treatments one day previously. This suggested that either the larvae were compromised or they were growing slower. Despite a lack of additive protection against a single strain pathogen attack being demonstrated, the potential benefit of multi-strain probiotics, as prophylactic measures against every-day microbial encounters in larviculture, would remain. Although 108 CFU ml-1 levels appeared to protect against pathogen attack slightly better, they were also potentially detrimental to normal larval rearing when administered in combination. Following the successful completion of the larval period and pathogen protection afforded with a combination of probiotics at 107 CFU ml-1, this level was recommended as the best concentration of each probiotic where combination administration would be applied. The work presented in this thesis supports the use of A. macleodii 0444 and Neptunomonas sp. 0536 in the routine rearing of GSM larvae. The ability to produce settled juvenile mussels, equal in numbers to those produced in normal healthy conditions, plus the benefits against pathogen attack led to the recommendation of their use on a routine prophylactic basis in GSM larval rearing. Their use for this purpose is intended in the near future. A provisional patent has been prepared and will be submitted shortly. It is anticipated that future work will continue with these probiotic strains to determine their potential benefit for other aquaculture species.

Dissertation (MHSc--Health Science) -- AUT University, 2008. / Includes bibliographical references. Also held in print (70 leaves ; 30 cm.) in North Shore Campus Theses Collection (T 616.8914 WOO)

Exegesis (MA--Art and Design) -- AUT University, 2008. / Includes bibliographical references. Also held in print (62 leaves : col. ill. ; 30 cm.) in the Archive at the City Campus (T 709.93 WIL)

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Harvesting is typically one of the largest cost components within a plantation forest rotation. A large proportion of New Zealand’s future harvest will be on steep terrain. Currently steep terrain harvesting is characterised by lower productivity and higher cost. It also has higher levels of manual or motor manual tasks such as setting chokers or tree felling, with a corresponding higher safety risk. The utilisation of ground-based machines on steep terrain has the potential to decrease harvest costs and improve safety. There is currently a push in New Zealand to increase the operating range. This is being done with a poor understanding of the slopes on which machines are currently operating and little understanding of the new risks steeper slopes might introduce. To better understand the true range of slopes on which forest machines are operating, a digital accelerometer was attached to 22 forest machines and provided real-time measurements of slope. The evaluated machines were grouped into one of four machine types; felling (n=4), shovelling (n=5), skidder (n=9) or European (n=4). The machine types were then analysed with respect to their machine slope (actual) and terrain slope (predicted) based on a digital terrain map. Two methods of calculating terrain slope were used, method one was based on a triangular irregular network (TIN) file with method two based off a raster file. Linear regression indicated that there was a relationship between machine slope and terrain slope for all four machine types, with the exception of European based machines, using the TIN method of slope calculation. All variables showed a poor coefficient of determination with the highest adjusted R squared single variable explaining 17% of the variation. All machines operated on slopes that exceed the New Zealand approved code of practice guideline of 30% and 40% slope for wheeled and tracked machines respectively. New Zealand based machines were shown to exceed the guidelines for terrain slope much more frequently, and by a greater margin, than European based machines.

New Zealand presently operates a "free market" system of employment and labour relations in which there are no prescribed or mandatory bargaining procedures. When this system was introduced by the Employment Contracts Act 1991 (the "ECA" ) it represented a dramatic departure from the previous system of state regulated collective bargaining, conciliation and arbitration: a system that had existed in New Zealand for almost a century. Although this change in approach was supported by free market advocates, it also generated considerable international and domestic criticism. In response to that criticism, a number of New Zealand politicians stated in 1996 that they would consider imposing on employers and employees a statutory duty to bargain in good faith. However, since the end of 1996, very little has occurred in respect of this issue. Indeed, it now appears that the current New Zealand Government may have abandoned this proposal altogether. If this is, in fact, the Government's decision, it ought to be viewed with concern, for it has been made without the benefit of informed debate. Little, if any, substantive consideration has been given to whether such a duty ought to be introduced, and if so, the form it might take and impact it might have. If an informed decision is to be made to enact a duty of this nature, or not, as the case may be, its merits must be the subject of further debate. This thesis will endeavour to contribute to that debate by examining how one approach to the duty to bargain in good faith, that which applies in British Columbia, Canada, might operate in New Zealand. This examination will consist of six chapters. The first will contextualise the New Zealand arguments on whether a duty of this nature ought to be introduced into the ECA. Chapter two will then examine the duty to bargain in good faith as it applies in British Columbia industrial relations. Chapter three will take that duty, and examine the extent to which it is currently replicated in New Zealand. It will be concluded that little of the substance of this duty is to be found in the law which presently governs the New Zealand labour market. Chapter four will assess the costs of introducing a duty of this nature into the ECA, particularly in terms of reduced efficiency and freedom. Chapter five will identify a number of specific issues that will require resolution if the duty is to operate effectively in New Zealand, and the terms of a suggested statutory amendment will be proffered. It will be concluded in chapter six that introducing a duty to bargain in good faith, akin to that which applies in British Columbia, would benefit New Zealand employers, employees and society as a whole. Further, it will be argued that such a duty must be introduced if labour bargaining in New Zealand is to occur in any meaningful way for most employees. And finally, it will be suggested that if this duty is to be introduced effectively, legislative amendment will be required. For these reasons, it will be asserted that the New Zealand Government ought to revisit the issue of introducing into the ECA a statutory duty to bargain in good faith.

Shellfish are an important food source however they are known to harbour bacteria, viruses and toxic chemicals that can be detrimental to their human consumers. Oysters have been associated with the gastroenteritis virus Norovirus. New Zealand has some of the highest cases of foodborne illness in the western world. This study investigated a possible link between periods of high rainfall and reported Norovirus outbreaks in four major cities in New Zealand (Auckland, Wellington, Christchurch and Dunedin) as well as national data. Norovirus is a highly infectious foodborne illness. Outbreaks of norovirus have been linked to the consumption of shellfish, and in particular oysters. Norovirus virions can enter the aquatic environment via sewage as a result of human shedding of the virus. This investigation into rainfall and Norovirus outbreaks found no statistically significant relationship, in a monthly or season setting. In addition the relationship between environmental cadmium levels and exposure levels in New Zealand was investigated through meta-analysis. Cadmium is a heavy metal commonly associated with the mining of copper and zinc ores. It is found naturally in the environment, in air land and oceans Increased exposure to cadmium is known to have a number of serious detrimental health effects, in particular this study investigates cadmiums immunosuppressive properties. Concentrations in New Zealand were compared with Canada, Italy and the UK to determine if New Zealand has a relatively high cadmium intake. Interestingly environmental levels (soil and oceanic) in New Zealand were low. Cadmium levels were higher in oysters than in mussels, with New Zealand oysters containing the highest concentration of cadmium presented. New Zealanders also had the highest cadmium burdens in the kidneys and the highest daily intakes. A No Observable Effect Level (NOEL) was calculated from mice data and compared to the daily intakes of the four countries. Both Canada and New Zealand were above this level. Shellfish are a common mechanism for exposure to both Norovirus and cadmium. The levels of cadmium present in the diet of New Zealanders may be sufficiently high to suppress the immune system, making it more vulnerable to infections of enteric diseases such as Norovirus.