Thesis (M. Phil.)--University of Hong Kong, 1978.

Because of the eutrophication resulting from increasing anthropogenic activities, hypoxia (i.e. dissolved oxygen < 2.8 mg O2 L-1) is on the rise globally. The objective of this research was to understand more about the effects of hypoxia on the marine benthic communities. Particularly, it focused on the latent effects and indirect effects of hypoxia by investigating how early exposure to hypoxia affect the later life stage of a marine gastropod Crepidula onyx, and how hypoxia alter the bacterial composition of biofilms and the subsequent larval settlement of marine invertebrates. In the first study, the larvae of C. onyx were exposed to 2, 3, and 6 mg O2 l-1. Under low food concentration (Isochrysis galbana at 1 × 105 cells l-1), larvae in both hypoxic treatments (2 and 3 mg O2 l-1) required a longer time to become competent to metamorphose. But when they did, they had a similar size and total lipid content to the control larvae. Moreover, the latent effects of early hypoxic exposure on the juvenile growth were evident. After 2 weeks development in field, the growth rate, mean dry weight and filtration rate of juveniles were significantly reduced in the hypoxic treatments. However, there was no discernible effect on larvae or juveniles when the food concentration during the larval stage was doubled (I. galbana at 2 × 105 cells l-1), suggesting that the latent effects of hypoxia can be offset by larval access to high algal concentration. In the second study, the biofilms were exposed to hypoxia and normoxia in microcosms for up to 7 days, and their bacterial community composition was analysed by terminal-restriction fragment length polymorphism (T-RFLP). The results suggested that hypoxia altered the bacterial community structure within biofilms, and the difference between the hypoxia and normoxia treatments increased through the length of exposure period. The resulting changes in biofilms did not alter the larval settlement response of a model species (i.e. C. onyx) in laboratory assays. Nevertheless, when the biofilms were deployed in the field to allow natural larval settlement and recruitment, biofilms that had been exposed to hypoxia altered the overall larval settlement pattern of different marine invertebrates, potentially leading to a shift in the benthic invertebrate community. This research suggested that periodic hypoxic events and the resulting exposure of organisms to hypoxia during their early development might have effects that persist across the life history. Moreover, it highlighted the possibility that the effects of hypoxia on species composition and structure of benthic invertebrate communities might be mediated through changes in biofilms and subsequently larval settlement and recruitment. To conclude, this research demonstrated that hypoxia could affect the growth in the later life stages of marine invertebrates and the recruitment of the benthic communities. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

Sea water samples were collected from different sampling stations along the Lebanese coast in the summer of 1994. Chemical, biological and physical analysis were conducted to assess the recreational water quality in Lebanon. / Some 125 samples were then analyzed for the presence of Cadmium and Mercury by atomic absorption spectrophotometry. Cadmium content, holding a mean 0.77 $ mu$g/L, was generally low for most areas with only a few elevated readings in Tripoli (1.89 $ mu$g/L), Checca (1.83 $ mu$g/L), Kaslik (0.79 $ mu$g/L), Beirut (1.19 $ mu$g/L) and Ramlet Al-Bayda (1.77 $ mu$g/L). Mercury content, holding a mean value of 0.06 mg/Kg (wet weight), was below the accepted tolerance limit of 0.5 mg/Kg for all sampling sites. / Some 128 samples were then analyzed for fecal coliforms (Escherichia coli and Streptococcus feacalis). Approximately, 50% of the sampling stations showed satisfactory results (less than 100 colonies/100 ml). High counts of fecal coliforms, over 500 colonies/100 ml, collected at Dora, Ramlet Al-Bayda and Antelias, reveal poor sea water quality and a public health hazards to swimmers and fishermen. / Some 36 samples were collected and analyzed for dissolved oxygen (DO), pH, salinity and temperature. For all sites sampled, DO averaged 4.03 mg/L, pH averaged 7.97, salinity averaged 38.77 ppt and temperature averaged 27.9$ sp circ$C. / The degree of pollution was found to be related to population density, industrial and human activity, continental runoffs and hydrological and meteorological conditions.

No description available.

Platform-ship collisions are fortunately rare events, but as the development of the offshore and oil industry and the gradually frequently used offloading operation, accidents become more and more frequent. The consequences of collisions are always severe, which includes loss of life, property and environmental damage. Thus It is important to predict the outcome of collision scenarios and assess the damage that may happen to the platform as well as the shuttle tanker.Collisions are always analyzed by means of the principle of the principle of energy conservation. Initial kinetic energy is dissipated by the two contact bodies as strain energy and in viscous force generation. There is also energy remained as the kinetic energy after the impact for both the striking and struck bodies, both for translational and rotational degrees of freedom. The external mechanics of the collision is easily evaluated, but the strain energy absorption can be rather difficult to evaluate in a correct way.In this thesis, A Samsung shuttle tanker and the Sevan SSP300 platform are analyzed as the striking and struck bodies, respectively. Structural configurations are described for both structures. Different impact scenarios are then discussed in the report, some of which are chosen to analyze in the thesis work. Non Linear Finite Element Analysis (NLFEA) model of the SSP300 platform is created. The shuttle tanker model is an exist one. One-sixth of the platform is modeled in detail with the correct stiffeners and other details, while for the other part, only the outer shell and the main bulkheads are modeled. For the tanker, adjustments are made in order to increase the calculation efficiency. Only the bow is remained in details. For the hull, only the outer shell is remained. For both structural models, adjustments are made to obtain the correct mass, added mass and inertial. Both models have a user defined material with the fracture criterion included. Integrated analysis is mainly performed. Then the integrated analysis is split into internal mechanics and external mechanics. Among these, integrated analysis and internal mechanics analysis are performed with finite element method, using the explicit NLFEA solver LS-DYNA. For the collision scenarios, only bow impact with different headings is considered. Two different impact velocities are chosen in both head on collision and collision with the glancing angle of 30 degrees. Energy absorption and force-displacement relationship can be obtained. Damage on the platform is also evaluated. Internal mechanics are then analyzed by changing the boundary condition and making the impact velocity constant. The purpose is to evaluate the damage with internal mechanics and then compare it with the results from integrated analysis. Liu&#146;s method, which is based on Stronge theory, is mainly used in external mechanics as a simplified method. Herein a Matlab program is established to calculate the energy dissipation and the velocity after the impact. Two other simplified methods are utilized to calculate the dissipated energy and then compare them with the results from NLFEA analysis. One is from the DNV-RP-C204 and the other one is from T.de Jonge&amp;L.laukeland&#146;s report. The latter one is an optimized method compared to the one from DNV rules, which includes the effect of roll motion. Results from the simplified methods and NLFEA method show good correlation. All the simplified methods overestimate the absorbed energy, which is conservative. Among these, Liu&#146;s method gives the best correlation with the NLFEA method. Two additional jobs are conducted in the end. Only the energy dissipation is analyzed in this section. One is changing the loading conditions of the two bodies. The energy dissipation becomes smaller after changing. The other one is changing the friction coefficient. The energy dissipated by the tanker is smaller, while by the platform is larger. But from the overall view, the energy does not show big difference with friction coefficient 0.15 and 0.4.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1991. / Includes bibliographical references (leaves 234-248) / Microfiche. / xv, 248 leaves, bound ill. 29 cm

Typescript. / Thesis--University of Hawaii, 1963. / Bibliography: leaves [80]-86. / iii, 86 leaves mount. illus., diagrs. (part fold.) tables

Diets of large marine predators have been extensively studied to assess interactions with fisheries, monitor links between diet and reproductive success, and understand trophic interactions in marine ecosystems. Since marine species can rarely be observed foraging directly, most studies rely on the identification of prey remains in stomach contents or faeces to determine the prey items being consumed. While this approach has provided a wealth of information, it has several limitations resulting primarily from difficulties identifying digested prey and from biased recovery of remains due to differential digestion. My thesis explores the use of molecular genetic methods in dietary studies of large marine predators. DNA-based identification techniques have been used in several diet studies, but the methods and applications are still in the early stages of development. Through a number of studies, I investigated the ability to recover genetic data from various dietary samples using a range of genetic techniques. A) Genetic screening for prey in the gut contents from a giant squid - I assessed the use of polymerase chain reaction (PCR)-based methods for isolation of prey DNA from an Architeuthis gut content sample. A taxonomically informative molecular marker was selected and a screening method developed using denaturing gradient gel electrophoresis. The methodology was used to identify prey from otherwise unidentifiable hard-part remains and the amorphous slurry component of the squid gut sample. The techniques developed here provided a framework for later chapters. B) Analysis of prey DNA in faeces of captive sea lions Part I: DNA detection, distribution and signal persistence - A feeding trial with captive Steller sea lions (Eumetopias jubatus) was carried out to investigate the use of genetic faecal analysis as a tool to study diet. I used group-specific PCR detection to determine: (i) the reliability of prey DNA recovery, (ii) the distribution of prey DNA within faeces and (iii) the persistence of the genetic signal after a prey item was removed from the diet. The proportions of prey DNA in several samples were also determined using a clone library approach to determine if DNA quantification could provide semi-quantitative diet composition data. Results show that the prey DNA could be reliably detected in sea lion faeces and the genetic signal could persist in samples up to 48 hours after ingestion. Proportions of prey DNA isolated from faeces were roughly proportional to the mass of the prey items consumed. Part II: DNA quantification - Quantitative real-time PCR was used to further investigate if quantitative diet composition data could be obtained through quantification of the DNA present in faeces. I quantified the relative amounts of DNA in three fish species being fed to captive sea lions, then determined the amount of DNA recovered from these prey items in the sea lions - faeces. The results indicate that diet composition estimates based on the relative amounts of DNA in faeces can be biased due to the differential survival of DNA from different fish species; however, these biases may be less than those commonly observed in the conventional analysis of prey hard remains. C) Quantification of damage in DNA recovered from faecal samples - I developed a general method to quantify the frequency of DNA damage present in specific gene regions. The technique was applied to assess the amount of DNA damage in predator and prey DNA recovered from sea lion faeces. The estimated frequency of DNA damage was always higher for the prey DNA than for the predator DNA within a faecal sample. The findings have implications for marker development and comparison of results obtained in future DNA-based diet studies. D) Studying seabird diet through genetic analysis of faeces - I investigated the diet of macaroni penguins (Eudyptes chrysolophus) through conventional analysis of stomach contents and through the analysis of prey DNA extracted from faeces. Genetic data was obtained from faecal samples using PCR tests to determine the presence or absence of DNA from potential diet items and also using a clone library approach. Approximately half of the faecal samples tested positive for one or more of the prey groups targeted with PCR tests. Euphausiid DNA was most commonly detected in early stages of chick rearing and DNA from a myctophid fish was prevalent in faeces collected later; this trend mirrored the data obtained from the stomach contents. Analysis of prey sequences in 'universal'clone libraries revealed a highly biased recovery of sequences from fish prey; this bias is most likely caused by the use of degenerate primers with a higher binding affinity for fish DNA template compared to DNA from other prey groups. Results obtained from the genetic and traditional approaches are compared, and potential future applications of the genetic techniques to studying seabird diet are discussed. This series of studies has contributed significantly to our understanding of the strengths and the limitations of DNA-based diet analysis. The work identifies situations where genetic methods can be successfully applied to study the diet of marine predators and provides guidance for future studies in this emerging field.

The currently most accepted population theory for reef fish was developed on tropical reefs and suggests that populations of most reef fish species are limited primarily by recruitment, with little post-recruitment resource limitation. I tested the validity of this theory for temperate reef fishes by examining growth rates in six common species from a number of isolated populations for evidence of resource limitation. If resources are limiting, spatial and temporal variation in recruitment and mortality should lead to isolated populations experiencing differing levels of resource availability, particularly food availability, which will be reflected in growth rates. I worked with six of the most common reef fishes found in Tasmanian waters so that any findings would form the basis of a broadly applicable model. These were Notolabrus tetricus, Notolabrus fucicola, Pictilabrus laticlavius, Pseudolabrus psittaculus, Penicipelta vittiger, and Meuschenia australis. Before examining growth rates it was first necessary to define the scale at which populations could be considered to be isolated. The short and long-term movement patterns of each species were studied using visual observations to interpret short-term patterns, and recaptures of tagged fish to interpret the long-term patterns. Methods of ageing each species were developed and validated, with growth rates of tagged fish being used to validate the use of otoliths for ageing. General growth curves are presented. For most of the species, there was some uncertainty in current texts about the sexual system used and the relationship between sex and dichromatism and dimorphism. To clarify this situation the reproductive biology of each species was examined. The relationship between sex and growth rate was also examined. For two species (N. tetricus and N. fucicola) annual growth data from tagged fish were obtained over a 3-4 year period, allowing inter-annual growth variability to be examined. As well as providing an insight into the variability of growth with time, these results also aid in the interpretation of growth curves determined from otolith ageing. In all species investigated, no significant differences in growth rates were detected between populations occupying similar habitats and subject to similar environmental conditions. These results suggest that post-recruitment resource limitation in the form of food limitation may not be an important factor influencing the post recruitment growth and survival of many temperate reef fishes with pelagic larval stages. This agrees with the assumptions made, but rarely tested, in current theories concerning the regulation of populations of reef fish, particularly those on temperate reefs.

Research into small-scale fisheries is often insufficient, resulting in limited data, because this type of fishery is inevitably constrained by financial considerations. This creates a challenge to provide adequate information to support sustainable management, particularly given the shift from single species management to more integrated spatial and multi-species management and, ultimately, to ecosystem based fisheries management (EBFM). Striped trumpeter (Latris lineata) is widely distributed around the temperate latitudes of the southern hemisphere. The species is iconic to Tasmania where it supports a small commercial fishery, and it is increasingly targeted by recreational fishers. This fish is common on most rocky reefs between 50 – 250 m around Tasmania. However, the historical data for striped trumpeter from Tasmania is patchy in time and space, reflecting opportunistic sampling over many years. Using striped trumpeter as an example of a small-scale data-limited fishery, this study applies a variety of techniques to describe key biological and ecological processes required for sustainable fisheries management. The study was divided into three themes. First, standard and novel analytical techniques were applied to evaluate data to provide key biological parameters required for single-species assessment. Second, stock structure was investigated on both local and global scales using molecular techniques and otolith morphometrics. Finally, recruitment processes were investigated based on otolith microchemistry and modelling of larval dispersal. Seasonal growth variability was observed over the first five years, with growth rates peaking approximately one month after the observed peak in sea surface temperature. The oldest fish in this study was 43 years. Lifetime growth was modelled using a modified twophase von Bertalanffy growth function, with the transition between growth phases linked to changes in physiological and life history traits, including offshore movement as fish approach maturity. Total mortality was estimated using catch curve analysis based on the standard and two-phase von Bertalanffy growth functions, and estimates of natural mortality were calculated using two empirical models, one based on longevity and the other based on the parameters L1 and k from both growth functions. The spawning season around Tasmania occurs in the austral spring, with peak spawning activity in September and October. Size at 50% maturity was estimated at 543 mm fork length (FL) for females (estimated age = 6.8 years) and 529 mm FL for males (estimated age = 6.2 years). Striped trumpeter is a multiple spawner with batch fecundity estimates ranging from 205,054 for a 2 kg fish (540 mm FL) to 2,351,029 for a 9.5 kg fish (800 mm FL). At the current minimum legal size limit of 450 mm total length (equivalent to approximately 425 mm FL), yield-per-recruit was estimated to be close to maximum, and spawning biomass-per-recruit (SPR) ranged from 35 – 52% of virgin stock, depending on the mortality estimates used. Otolith morphometrics, in particular elliptical Fourier analysis of otolith shape, indicated little to no connectivity between the striped trumpeter population of Tasmania and the St. Paul/ Amsterdam Island populations. A molecular assessment of mtDNA confirmed this finding. In addition, the DNA sequence analysis indicated that the New Zealand striped trumpeter population was genetically distinct from the Tasmanian and St. Paul/ Amsterdam Island populations. DNA sequence analysis also indicated that the population around Tasmania is a single population. The affinity of juvenile striped trumpeter to inshore reefs has been suggested from anecdotal fishing observations. Using otolith microchemistry the comparative contribution of juvenile striped trumpeter from shallow inshore habitats to the adult population was estimated. Juvenile striped trumpeter from a strong recruitment pulse (1993 cohort) were collected at age two from inshore reefs and as adults at age six from deeper offshore reefs around the coast of Tasmania. Natural variations were identified in the concentrations of lithium and strontium within the incremental structure of the observed otoliths. Discriminant analysis suggested that 70% of adults sampled originated from an inshore juvenile habitat, 13% were from deeper reefs and 17% could not be statistically allocated with confidence. An integrated bio-physical larval dispersal model was developed in an attempt to explain the high degree of inter-annual recruitment variability displayed by this species. The model utilised information developed through the course of this study on reproductive biology, ontogenic habitat preferences and stock structuring as well as additional information on striped trumpeter larval biology from aquaculture trials to generate realistic scenarios. While the model was unable to accurately predict observed interannual recruitment variability, it did provide insights to important source and settlement regions as well as the importance of the addition of biological components, such as: timing of spawning, growth and mortality. Through efficient data-mining, novel methods and technological advancements this study has provided robust scientific advice to support the management of the striped trumpeter fishery. Information has been collated to support traditional single-species management and also for developing spatial fisheries measures, leading to a more ecosystem based approach to fisheries management. Otoliths proved to be valuable in several areas, and small-scale fisheries would be advised to initiate otolith collections even though analysis may not be planned for some time. This study demonstrates how targeted research could be used in other small-scale data limited fisheries in a cost effective manner to provide information for sustainable management.