This study embraces two aspects of closed system culture: (a) a comparative study of four different biological filtration treatments, and (b) a quantitative determination of the nitrogen flow in a particular biological filtration system. Twenty 0,5 g juvenile Penaeus indicus Milne Edwards were cultured for approximately two months in four different kinds of sea water recirculatory systems with bacterial filtration, algal filtration, algar plus bacterial filtration and water exchange (25% every 3 days). Growth was comparable to that found in the literature for P. indicus. Nitrification occurred in all systems irrespective of the type of biological filtration employed. Ammonia, nitrite and nitrate levels were reduced by the algae, but nitrate accumulated to approximately 30 mg NO¯³ -Nℓ¯¹ in those systems without algae. Depletion of trace elements (Cu, Fe, Zn, Hn and Co) by the algae did not occur due to trace metal replenishment from the addition of food. No marked changes occurred in the concentrations of the major cations (Ca⁺⁺, Mg⁺⁺, Na⁺ and K⁺), but a small increase in Ca⁺⁺ levels was detectable in those systems with oyster shell chips in the filtration medium. Only minor changes occurred in oxygen or pH values in the various systems tested. Inorganic carbon levels showed major increases in the algal filtration systems, while a slight drop occurred in the bacterial filtration systems. The increase in the algal filtration systems was thought to be due to the formation of carbonates and bicarbonates by the reaction of respiratory CO₂ with unionized ammonia and water. Suggestions are made as to how closed systems can be improved upon. By determining the rate of excretion of P.indicus as related to size and temperature, its faecal production, and the nitrogen content of P.indicus, its food and faeces, the nitrogen flow within a system could be calculated. P.indicus was found to have an assimilation efficiency of 88,93% and a food conversion ratio of 3,49:1. Of the total dietary nitrogen input into the system, P.indicus ingested 69,02% - 19,80% of which was used for growth, 41,58% excreted and 7,64% lost as faeces. The remaining 30,98% of the total nitrogen input can be regarded as excess food nitrogen. The total nitrogen loading on the biological filtration system was found to be 80,20% of the total input of dietary nitrogen. The ability of various types of filamentous algae to remove these nitrogen compounds was determined. Suggestions are made as to the application of this information on nitrogen flow to the culture of P.indicus

The hydrodynamics of three different shark heads: Eusphyra blochii (Winghead shark), Carcharhinus acronotus (Blacknose shark) and Sphyrna tiburo (Bonnethead shark) were investigated. Force transducer measurement was used to explore how the cephalofoil (wing-shaped head) affects maneuverability and efficiency. As the dynamic behavior of maneuvering wings differs from that of the steady state motion, experiments have been conducted to simulate: 1) steady-state (no yaw motion) constant velocity swimming, 2) constant forward velocity with yawing motion of the head and 3) turning maneuvers. Different range of velocities, angle of attack, yaw frequency and yaw amplitude were tested. Drag and lift coefficients were calculated and compared. The lift coefficient of Winghead shark is much higher compared to the other sharks. The lift-to-drag ratio showed that the Winghead shark has a hydrodynamic advantage compared to Blacknose shark and Bonnethead shark. / by Julien Barousse. / Thesis (M.S.C.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

Inaug.-diss.--Basel. / Curriculum vitae. "Literaturverzeichnis": p. [154]-163.

Thesis (M.S.) in Marine Biology--University of Maine, 2002. / Includes vita. Bibliography: leaves 61-69.

Self-recruiting species (SRS) are the aquatic animals that do not require repeated stocking in farmer managed aquatic systems (FMAS) and can be of indigenous or exotic origin (Little, 2002). Current concept of conventional aquaculture greatly underestimated the contribution of SRS to the livelihoods and particularly nutritional security of the poor. The present study examines the role of SRS in poverty focused aquaculture. The role of SRS in aquaculture was evaluated from the perspective of people dependent on them in terms of well-being, gender, resource access and broader livelihoods in the northwest and south-central region of Bangladesh. SRS management practices, already an existing component of aquaculture in FMAS, were explored to define sustainable management strategies that benefited poor. The thesis uses a livelihoods framework within a methodological context of participatory action research at household, community and national level. The process begins with a Participatory Community Appraisal (PCA) in 18 communities with 360 participants which then directs further investigation at household level through survey, longitudinal study farmer and farmer participatory action research over a systematic 4 year investigation from 2001 to 2004. At the PCA stage, the context of livelihoods, importance of popular aquatic animals and their different sources were examined. The more frequently mentioned and higher scored SRS by the communities were Clarias batrachus, Anabas testudineus, Macrobrachium sp., Puntius sp., Heteropneustes fossilis, Channa punctatus, Mystus vittatus, Amblypharyngodon mola, Channa striata, Macrognathus puncalus. The sources of these aquatic animals provided a better understanding of the diverse typology of farmer managed aquatic systems (FMAS) and showed the importance of both FMAS and open systems to sustain a self-supporting population of aquatic animals for nutritional security of the poor. Rice and other crop farming, fish culture, livestock and poultry rearing, service and business were found to be common occupations among better off households where as share-cropping, petty trade, fishing, selling agricultural and non-agricultural labour were of greater importance to poorer households. Both gender and well-being affected livelihoods with significant differences in involvement of the better off and poorer. PCA findings were later validated at a national level stakeholder workshop with 138 government, non-government officials, researchers and academics which established a broader understanding of the prospects and constraints of SRS culture and conservation. The baseline survey with 119 households further examined the characteristics and access of key farmers to managed aquatic systems, livelihood assets, vulnerability and the behaviours of households managing SRS. Access to FMAS and SRS are of much greater importance to poorer than to the rich. Positive, negative and neutral attitudes towards managing SRS were not significantly affected by well-being. Access to appropriate types of FMAS, SRS management knowledge, traditional taste, greater involvement in non-farm activities, family need were all associated with the SRS positive attitude. Results from the year round longitudinal study with 50 households focused on the seasonal dynamics of food consumption and its connection to livelihoods in terms of sources, income and expenditure. Aquatic animals are the 3rd most important contributor to the rural Bangladeshi diet after cereal and vegetables by weight and the 2nd most important contributor by price after cereal. FMASs are important source of aquatic animals compared to other sources such as open system, market and given sources (free from neighbours and relatives). SRS were accounts for 52% of the total aquatic animal consumption. Even among some very low income vulnerable groups such as day labourers and rickshaw pullers, SRS was found important in their diet. Poorer households rely significantly more on SRS than richer households. The total amount of SRS consumed by thenhosueholds over the year was strongly correlated with total number of SRS species consumed per year and further emphasised the significance of maintaining biodiversity. The pre monsoon dry period as April and May were low consumption periods in both zones. Rainy and post rainy season July to October were the peak consumption months in the northwest zone and June to November in south-central zone. The year round farmer participatory trial with 29 farmers confirmed the value of SRS within culture systems with lack of any major conflicts in the husbandry of non-stocked species with popular carps in the system which, in the past regarded as weed fish and have been generally excluded from formal aquaculture. The study found a range of species of both commercial and non-commercial SRS have greater significance to the poor than to the richer households particularly in terms of household consumption, income and social value. More deliberate attention towards avoidance of negative actions towards SRS in aquaculture in the lean season may also expand niche benefits for non-pond owners and vulnerable social groups such as fishers. Current investigations also revealed the complementarities of stocked fish particularly during dry months when SRS are less available. In spite of the poor having limited access to ponds, the seasonal scarcity of water in dry seasons and habitat degradation, SRS remains an important and valuable food item for the poor in low income vegetable scarce months. The study recommends future emphasis on the management and conservation of both commercial and non-commercial (mainly for consumption) SRS in FMAS particularly during the lean season and also to maintain the integrity of the permeable nature of FMAS and its linkage with the broader open systems for the sustained availability of such self-recruiting population. Finally the study greatly influenced the perception of utilising both stocked and non-stocked species in formal aquaculture. It is necessary to take urgent steps to avoid negative actions to damage SRS and formulate an integrated approach to water, agriculture, environment and fisheries management to sustain them for current and future nutritional and livelihoods security of the poor.

Thesis (MFA)--Rochester Institute of Technology, 1988. / Includes bibliographical references (leaf 51).

Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, Discipline of Ecological and Evolutionary Biology, 2008. / "December 2007" Bibliography: leaves 117-123. Also available in print form.

Thesis (Ph. D.)--University of California, San Diego, 1998. / Vita. Includes bibliographical references.

Thesis--University of Lund. / Extra t.p. with thesis statement inserted. Bibliography: p. 9.

Thesis (Ph. D.) - Oregon State University. / Bibliography: leaves 72-76.