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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Effects of temperature, salinity and photoperiod on the deposition of growth increments in statoliths of the oval squid Sepioteuthis lessoniana Lesson, 1830 (Cephalopoda: Loliginidae) during early stages

Chung, Wen-Sung 29 July 2003 (has links)
Cephalopods become one of the most important commercial marine resources worldwide. The knowledge of the basic biology and population dynamics of these resources is the way to ensure the resource to be utilized properly. In Taiwan, cephalopods are traditionally used and prized as foods with high market price. Sepioteuthis lessoniana is an important fishery species. Its distribution is concentrated around the northeastern and the southern coasts of Taiwan, and the Peng-Hu Island. Although there are some investigations on the statolith of the adults, studies on early stages are scarce. In this study, we use the known-age statoliths incubated in the different conditions to relate with those factors, i.e., temperature, salinity, and photoperiod, which influenced the ring formations during the embryonic and larval stages. From April to September, several clusters of bamboos, 3 ~ 4 m long, 1 ~ 2 m wide, were set on the sea bed at a depth of 16 to 20 m to attract their spawning, and the egg-strings were then transported to the laboratory. When the development of the embryo reached stage 24, iris of eyes being prominent as a colour circle and statolith being formed, they were transferred into different rearing conditions, i.e., 20, 25, 30, 35 o/oo and 15, 20, 25, 30 oC. The durations from stage 24 to hatching were different among all different rearing conditions. The statoliths were extracted and mounted in Crystal Bond thermoplastic cement for reading their growth rings. In the normal condition (25 oC and 35 o/oo), the duration from stage 24 to hatching is 9 ~ 16 days. Although the rings can be counted in each specimen, the numbers do not match between the embryonic rings and the developmental duration. Changes on the shape of the statolith were observed among different incubated conditions. The shape of the statolith at hatching had obvious differences among different embryonic developmental conditions. The statolith developed in the colder environment had smaller dorsal dome, thinner and shorter rostrum than that developed in the warmer condition. Using the shape of this embryonic ring was to be applied to measure the variation of the shape of the statolith. This is a useful tool to know the temperature factor during embryonic development by comparing with the shape of the hatchling¡¦s statolith. After hatching, squid hatchlings were separated to incubate in two different photoperiod regimes, 12 hr: 12 hr and 24 hr constant light conditions. Squid larvae were maintained as long as possible. Although the trend which older squids have more increments on the statolith than younger squids is consistent, the slope between the increments and survival days is less than one. The time required to form one ring on the statolith is needed for more than one day. Bell-shaped distributions can be found in several analyses in this study, especially with large sample size in 25 oC at 35 o/oo. If the sample size was small, the bell-shaped distribution would be obscure. This may result in oversimplification in interpretating the result. Sometimes this kind of problem could be inevitable because collecting large enough sample size was difficult or impossible. In any validation exercise, it would be difficult to obtain data for the whole life cycle. This study indicated that the hypothesis of daily-increment for the whole life history required further verification with larger sample size and wider size ranges of the tropical squids in future.
122

Effect of salinity on particle release and hydraulic conductivity in sediments /

Blume, Theresa. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.
123

Short and long term physiological and biochemical adaptations of the eel (Anguilla japonica) to changes of salinity.

Ho, Shuk-mei, January 1977 (has links)
Thesis--Ph. D., University of Hong Kong, 1978.
124

Efficiency of low salinity polymer flooding in sandstone cores

Kozaki, Chie 02 August 2012 (has links)
Waterflooding has been used for many decades as a way of recovering oil from petroleum reservoirs. Historically the salinity of the injection water has not been regarded as a key variable in determining the amount of oil recovered. In recent years, however, evidence of increased oil recovery by injection of low salinity water has been observed in laboratories and fields. The technique is getting wider attention in the oil industry because it is more cost-effective than other EOR techniques. The present work demonstrates the synergy of low salinity water flooding and polymer flooding in the laboratory scale. The use of low salinity polymer solution in polymer flooding has significant benefits because considerably lower amount of polymer is required to make the solution of a target viscosity. Low salinity polymer flooding can also increase oil recovery by lowering residual oil saturation and achieve faster oil recovery by improving sweep efficiency. Several coreflood experiments were conducted to study the efficiency of low salinity water flooding and low salinity polymer flooding in mixed-wet Berea sandstone cores. All the core samples were aged with a crude oil at 90oC for 30-60 days before the tests. All the polymer floods were conducted in the tertiary mode. A synthetic formation brine (33,800 ppm) was chosen for high salinity water and a NaCl brine (1,000 ppm) for low salinity water. Medium molecular weight HPAM polymer, FlopaamTM 3330S was used due to the low/moderate permeability of the Berea sandstone cores used in this study. Coreflood tests indicate that injection of low salinity polymer solution reduces residual oil saturation by 5-10% over that of the high salinity waterflood. A part of the residual saturation reduction is due to low salinity and this reduction is achieved in less pore volumes of injection in the presence of polymers. Effluent ion analysis from both low salinity water flooding and low salinity polymer flooding showed a slight increase in divalent cation concentrations after the polymer breakthrough. Cation bridging may play a role in oil wettability and low salinity injection desorbs some of these cations. / text
125

Field measurements of soil salinity by the four-electrode and the salinity probes

Marwan, Mukhtar Mohamed January 1980 (has links)
No description available.
126

PHYSIOLOGICAL CHANGES OCCURRING IN PHASEOLUS VULGARIS L. PLANTS SUBJECTEDTO SODIUM-CHLORIDE SALINITY

Prisco, José Tarquínio, 1941- January 1971 (has links)
No description available.
127

The effects of hypersalinity upon the eggs and prolarvae of the Gulf of California grunion, Leuresthes sardina (Jenkins and Evermann 1888)

Constant, Charles Louis, 1944- January 1976 (has links)
No description available.
128

Salt Tolerance and Current Status of the Date Palms in the United Arab Emirates

Alhammadi, Mohamed Salman January 2006 (has links)
This study aimed to address the current status of the United Arab Emirates date palms. The first chapter focused on the development of the date palm sector in the UAE. A huge increase in the date palm number was achieved in the past few decades. In the same time, there are critical issues facing this development, such as water demand, salinity, and Red Palm Weevil. The second chapter is a greenhouse experiment to test the growth of twelve date palm seeds at four NaCl levels, control, 3000, 6000, and 12000 ppm. Optimal growth found at control and 3000 ppm of NaCl. Relative growth rate (RGR), biomass, and NL decreased significantly by increasing salinity; however, no significant differences were observed in the average SGR for any cultivars. Increased NaCl leads to significant decreases in K+, Mg2+, and Ca2+ contents of plants. Na:K ratios were lower in shoots than in roots. Lulu, Fard, Khnaizi, Nabtat Safi, and Razez cultivars showed higher RGR and biomasses whereas Khnaizi, Mesally, and Safri had higher Na:K ratios than other cultivars in the control indicating higher Na+ discriminations from plant parts. The third chapter studied the vegetation change in the eastern region of the UAE. Due to shortage of fresh water resources, the vegetation of the eastern region of the UAE has experienced a series of declines resulting from salinization of groundwater. To assess these changes, field measurements combined with Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) based Soil Adjusted Vegetation Index (SAVI) were analyzed. Images from two dates, 1987 and 2000 were acquired to enable the computation of the greenness anomalies for three sites in the eastern region, Fujairah, Kalba, and Hatta. The results show an overall increase in the agricultural area, associated with a severe decrease in vegetation greenness and health conditions, particularly in the Kalba study area. The SAVI values decreased with increased soil salinity, permitting the identification of salt-affected areas. Potential areas of further research range from studying the effects of tree spacing and understory crops as immediate and potential solutions to maintain productivity and mitigate the salinity problem.
129

Mating behaviour, epibiotic growth, and the effect of salinity on grooming activity in the hermaphroditic shrimp Lysmata wurdemanni

Giri, Tuhin 30 September 2004 (has links)
Many species of caridean shrimp are protandrous hermaphrodites, maturing initially as males but developing into females as they age and grow. A unique sexual system was recently discovered in the peppermint shrimp, Lysmata wurdemanni. In this species, individuals are initially male, but become simultaneous functional hermaphrodites over time. As in most caridean shrimp, L. wurdemanni can mate as a male during the intermoult period, but can reproduce through female function for only a short period after moulting. Ecdysis does not occur en masse in this species, and thus the operational sex ratio found in populations of L. wurdemanni is extremely male-biased. Sexual selection theory suggests that these conditions will result in increased competition for access to mates. Evolutionary pressures should therefore have selected for mechanisms that permit individuals to quickly identify and locate potential mating partners. L. wurdemanni were exposed to chemical stimuli collected from recently moulted conspecifics of varying reproductive condition. Test animals were able to distinguish among the different conditions, and physically manipulated only the plastic nozzle used to pump solutions collected from shrimp with ovaries filled with vitellogenic oocytes. It was subsequently hypothesized that methyl farnesoate, a hormone associated with ovarian maturation in crustaceans, might be a key component of sex pheromones used by L. wurdemanni. However, a series of methyl farnesoate concentrations did not elicit responses, indicating this species does not use this hormone alone when determining reproductive condition. Reproductive behaviour in L. wurdemanni was observed to differ both before and after copulation, as well as with increasing population density. Intermoult individuals were more likely to approach, follow and remain in the vicinity of a near-moult shrimp before mating could occur, and under high density conditions. The near-moult shrimp approached conspecifics only under low density conditions, and performed rapid escape behaviours only after copulation had occurred. The unusual occurrence of epibiota upon L. wurdemanni was described, and the location, size and age of barnacles quantified. The effect of salinity upon grooming activities was tested. Results indicated that carapace grooming was depressed at low salinities, and could account for the considerable epibiota found in this region.
130

Exploring the possibility of transforming food crops for salinity tolerance using the TMT gene encoding thiol methyltransferase enzyme

Ali, Arshad January 2010 (has links)
Soil salinity is a serious environmental stress threatening productivity of major crops worldwide. Among the various biotic and abiotic strategies that exist, transgenic technologies provide a promising avenue to reduce yield losses in crops under saline environments. Recently, transgenic technology involving the TMT gene encoding thiol methyltransferase enzyme has been suggested as an effective solution for engineering a chloride detoxification capability into a high value crops to improve tolerance against chloride ion toxicity under saline environments. This proposed mechanism, however, results in the emission of methyl chloride (CH3Cl) from plants, which has deleterious effects on stratospheric ozone. This study was performed to examine the relationship between salt tolerance and chloride volatilizing capacity of transgenic plants containing TMT gene as well as to explore the possibility of generating transgenic rice crop containing TMT gene for salinity tolerance. To achieve these objectives, transgenic tobacco plants containing TMT gene were grown in comparison with wild type tobacco plants under three levels of sodium chloride (NaCl) salinity (0, 100 and 200 mM), three levels of soil water content (40%, 60% and 80% of the field capacity) and their tolerance to NaCl and water stress was studied. Plant growth parameters recorded included plant height, number of leaves, leaf area, stem dry weight, leaf dry weight, root dry weight, plant dry biomass and root/shoot ratio. Similarly, both types of plants were exposed to five levels of NaCl concentrations (0, 50, 100, 150 and 200 mM) and three levels of soil water content (40%, 60% and 80% of the field capacity), and the quantity of CH3Cl emitted was recorded. Significant decrease in plants growth parameters of both types of plants were recorded upon exposure to salinity and water stress. Under 100 mM NaCl, however, transgenic plants showed better tolerance to salinity by suffering less reduction in growth parameters compared to wild type plants. Under 200 mM NaCl, growth of both types of plants was completely inhibited. The interactive effects of salinity and water stress were more pronounced in wild type plants than in transgenic plants. Results also showed that all engineered plants acquired an ability to efficiently transform chloride ion to CH3Cl, and the rate of such transformation was higher under greater NaCl and soil water content compared to lower NaCl concentrations and soil water content. In order to explore the possibility of generating a transgenic food crop using TMT gene, a hypothetical transgenic rice crop was grown over 27 million hectares of the saline coastal areas of south and southeast Asia and the possible emission of CH3Cl from such ecosystem was inferred based on the CH3Cl emission data obtained from transgenic tobacco plants. The estimates showed that the possible CH3Cl emission from such ecosystem would be 219.21 Gg which is equivalent to 5.36 % of the global atmospheric emissions of CH3Cl.

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