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Opakapaka (Pristipomoides filamentosus) is a snapper (family Lutjanidae) native to the waters around Hawaii. Recent population declines of this commercially important species have increased interest in the culture of this fish. Survival of this fish through the larval period in culture has been consistently low, usually not exceeding 2%. The aim of this thesis was to provide an extensive diagnostic report of diseases affecting opakapaka larvae in culture. Opakapaka larvae mortality was found to be the result of a synergy of factors including larvae development stage, larvae nutrition, environmental conditions, and the presence of infectious agents. During culture, high larval mortalities occur around first feeding and around a period of rapid development. Crucial periods of development in both the digestive system and the respiratory system coincided with these catastrophic mortality events. It is therefore suspected that failure to complete the progression of development from one stage to the next is partially responsible for low larvae survival. A large proportion of opakapaka surviving to the juvenile stage had deformed jaws and/or vertebral columns. Therefore, the development of the jaw and other skeletal elements was investigated. Lower jaw deformities were found to occur as early as 2 days post hatch and larvae with some deformity represented roughly 30% of the population. Given the severity of these deformities, it is likely that this results in increased larvae mortality. Due to the identified risk of ammonia toxicity, experiments were designed to determine the concentration of ammonia lethal to opakapaka larvae. The 50% lethal dose for post-hatch opakapaka larvae was found to be 1.4 mg/L total nitrogen. Ammonia toxicity could have been a factor in opakapaka larvae mortality, because this concentration was lower than that observed in larvae rearing tanks. The evaluation of the role of infectious disease in opakapaka culture showed that current infections are primarily opportunistic. Observed infections included bacterial gill disease and external lungal infection. Although infectious disease is not currently a significant cause of mortality, continued surveillance for infectious disease introduction is recommended. The success of intensive opakapaka culture hinges on the ability to culture a large number of opakapaka to the juvenile stage. As a result of this study, major issues of concern in opakapaka culture were identified. This information could provide direction for culturists in the refinement of opakapaka culture and subsequent improvement of larvae survival. / Graduation date: 2005

Chaoborus americanus larvae were used in laboratory experiments to assess their efficiency at decreasing mosquito larval populations. Third and fourth instar Chaoborus americanus larvae were independently fed assemblages of single prey species to test hunger and several prey species to test preference. Prey species included Daphnia and the four Aedes aegypti larval instars. The results show that Chaoborus americanus larvae will choose early instar mosquito larvae over Daphnia, however, this preference decreases as the mosquito larvae become older. Third instar Chaoborus americanus larvae will choose first instar mosquito larvae over Daphnia 76% of the time, whereas they will select third instar mosquito larvae only 30% of the time. Fourth instar Chaoborus americanus larvae will choose first instar mosquito larvae 94% of the time, and select fourth instar mosquito larvae only 3% of the time. Crowding also has an effect on feeding times; individual Chaoborus larvae take more time to ingest their prey items than do individuals within a group. Chaoborus americanus larvae are good biological control agents within a laboratory setting.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 124-130) / Microfiche. / xv, 130 leaves, bound ill. 29 cm

Most benthic marine invertebrates have long-lived planktonic ciliated larvae that must feed and grow to reach metamorphosis. Because ciliated cells in animals are unable to divide it is of considerable interest how ciliated larvae are able to grow. To understand how ciliated larvae grow I compared cell proliferation patterns in several species with planktotrophic larvae from five different phyla (Nemertea, Mollusca, Phoronida, Echinodermata, and Annelida). Cell proliferation events were detected using anti-phosphohistone antibody labeling, BrdU assays, and confocal microscopy. Studied larvae included some with monociliated epithelia (pluteus, bipinnaria, actinotroch, and mitraria) and others with multiciliated epithelia (metatrochophore, pilidium, and veliger). Dividing cells were detected in all studied larvae, but the pattern of dividing cells varied among types and correlated with the kind of epithelium (mono- vs. multiciliated) and phylogeny (e.g. protostome vs. deuterostome). Running z-projection movies of the actinotroch, mitraria, veliger and pilidium are included as supplemental files.

Coastal hydrodynamics regulate population dynamics through the distribution and dispersal of the meroplankton of many benthic invertebrates. I examined the hydrodynamics at four different sites on the south-east coast of South Africa and coupled them with larval sampling done at high temporal and spatial resolution. Day and night sampling was done at all four sites and a continuous 24 hour study was done in one site, both forms of sampling were carried out in autumn and spring. Samples were taken at two stations, 900 metres offshore and 300 metres apart, within each site. Water properties measured were depth, temperature and current velocity and direction. Plankton samples were collected using a plankton pump at various depths, from the surface, bottom and either side of the thermocline when present. A wide range of taxa (mostly bryozoans, bivalves, barnacles and decapods) was examined. 2-way ANOVAs were used to test the effects of time and depth on each taxon. In addition, multiple regression analyses were performed on each taxon to investigate the effects of hydrodynamics on the distribution of larvae. Bryozoanlarvae proved to be positively phototactic whilst bivalve veligers, barnacle larvae and decapod zoeae performed diel vertical migration. Turbulence and temperature had an effect on the vertical distribution/migration of decapod zoeae. These results highlight the role of taxon-specific responses to flow and the potential differential effects on larval retention and ultimately connectivity of benthic populations.

No description available.

An artificial larval medium for colonized Culicoides guttipennis was developed. Microorganisms in decaying leaf matter were present in the original laboratory diet. These were believed to be the main food of C. guttipennis larvae. This was verified by sterilizing the leaf matter to kill the organisms present. Larvae did not develop beyond the first instar in this medium, but adults were produced from non-sterilized leaf matter. The objective was to develop cultures of various microorganisms and find one that would be best for rearing C. guttipennis larvae in producing more adults. A simple hay-infusion medium inoculated with stump-hole microorganisms was found more effective than all other cultures screened in rearing the larvae. This culture consisted of stump-hole microorganisms inoculated fresh each week from stored stumphole contents. It was compared with the same culture containing stumphole microorganisms completely adapted to a laboratory environment. The former was better in rearing C. guttipennis larvae. A final experiment evaluated the incorporation of vermiculite as an artificial substrate. This proved successful in rearing larvae and producing large numbers of adults. This culture was superior over the larval rearing medium of decaying leaf matter. Development of a successful artificial larval medium for colonized C. guttipennis will aid in establishing other laboratory colonies of related Culicoides species. / Master of Science

Wound healing and recovery from injury were investigated in eggs and larvae of herring (Clupea harengus L.), plaice (Pleuronectes platessa L.) and salmon (Salmo salar L.). The resistance of herring eggs to mecha.nical damage was first examined. The chorion of eggs before and just after fertilisation could be burst by loads of 4-30 g but eggs 5 h post-fertilisation could withstand over 1000 g without bursting. Resistance remained high until just before hatching when it decreased to 20-680 g. The vitelline membrane, however, showed a lower resistance at all stages. Early herring and plaice larvae were caught and eaten by medusae (Aurelia aurita, Tiaropsis multiserrata, Bougainvillea sp.), hydroids (Sarsia sp.), megalopa larvae of the prawn Nephrops norvegicus and adult mysids. Early herring larvae survived minor stings from an Aurelia ephyra, and also experimentally inflicted lesions such as superficial scratches, suction wounds and amputation of up to 2 mm of the tail in sea water. The caudal region of the primordial fin regenerated within a month when less than 1 mm was cut off. Yoll, sac and first feeding herring also survived an incision of 0.3 mm long through the body ventral to the notochord and dorsal to the gut; in starving larvae survival was poorer in the later stages of starvation. When skin was removed in larvae of all 3 species the mortality depended on the area of the lesion, thp maximum area tolerated increasing with larval size. In sea water the threshold area was 0.1-0.2 mm2 dO.r 6-8 mm long plaice, <: 0.3 mm for 10-13 mm long herring and 0.3-0.4 mm for 14-17 mm long herring. In river water the threshold was 1~2mm for 19':1l2m1m long saImon and 6.5-8 mm for 26-28 mm long salmon. The thresholds w ore about 1-3% of the total body surface area. Tolerance was increased in isosmotic salinities, the threshold area being as high as 10-14% of the body surface in 24-28 mm long salmon in 8%0. Healing of skin lesions was observed in vivo and by histology, the main response being a mass migration of epidermal cells from the periphery of the lesion. Wound areas of 0.1-7 mm closed in 4-12 h, the mean rates of cell migration being 40-110JUm/h at 10_11°C. The rate of migration was temperature dependent. The normal skin structure was restored with regeneration of a new basement membrane and dermis within 3 weeks. Older stage larvae showed an inflammatory response similar to adult fish.

No description available.