Thesis (M.S.)--Rhodes University, 2002. / Title from PDF t.p. (viewed on July 22, 2006). Includes bibliographical references (p. 68-88).

In recent years, evidence has been found of Diel Vertical Migration (DVM) in zooplankton during the Polar Night in the Arctic Ocean. However, the drivers of this behaviour during an apparent lack of illumination and food are poorly understood, as is its spatial extent across the Arctic Ocean. A novel dataset comprising 58 deployments of moored Acoustic Doppler Current Profilers is used in this study to observe the vertical migratory behaviour of zooplankton on a pan-Arctic scale. Methods of circadian rhythm analysis are applied to detect synchronous activity. South of 75°N, DVM continues throughout winter (albeit with reduced vertical amplitude when compared to other times of the year). DVM is seen to cease for a short period of time (up to 50 days) at latitudes between 75° and 82°N. The duration for which DVM ceases is controlled primarily by latitude (and therefore the altitude of the sun), but is modified by sea-ice presence and other environmental parameters. A DVM pattern is not seen at 90°N at any time of the year, but ~365 day periodicity is detected in the surface backscatter levels at this latitude. During the Polar Night, the moon controls the vertical positioning of zooplankton across the Arctic. Aggregations at depth coincide with an avoidance of the surface for several (< 6) days over the full moon. The deepest aggregation is seen at 110 m, indicating a depth limit of moonlight perception. A new type of migratory behaviour is described: Lunar Vertical Migration (LVM) which exists as LVM-day (24.8 hour periodicity) and LVM-month (29.5 day periodicity) on a pan-Arctic scale. The strongest LVM-day is seen at 50 m depth. Sea-ice and cloud are found to modify both of these lunar responses. The results presented by this thesis show continuous activity throughout winter, and challenge assumptions of a quiescent Polar Night.

No description available.

by Tam, Pui Fun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 147-166). / Abstract also in Chinese. / List of Tables --- p.i / List of Figures --- p.ii / List of Plates --- p.v / Acknowledgements --- p.vi / Abstract (in English) --- p.vii / Abstract (in Chinese) --- p.ix / Chapter Chapter 1. --- General introduction --- p.1 / Chapter Chapter 2. --- Temporal and spatial distribution of Copepoda in the Zhujiang River estuary --- p.3 / Chapter 2.1 --- Literature review --- p.3 / Chapter 2.1.1 --- Physical properties of estuaries --- p.3 / Chapter 2.1.2 --- Factors affecting the zooplankton community --- p.4 / Chapter 2.1.2.1 --- Temperature --- p.4 / Chapter 2.1.2.2 --- River discharge and salinity --- p.5 / Chapter 2.1.2.3 --- Coastal hydrography --- p.6 / Chapter 2.1.2.4 --- Biological factors --- p.6 / Chapter 2.1.3 --- Site description of the Zhujiang River estuary --- p.7 / Chapter 2.2 --- Introduction --- p.9 / Chapter 2.3 --- Materials and methods --- p.10 / Chapter 2.4 --- Results --- p.13 / Chapter 2.4.1 --- Physical parameters and chlorophyll concentration --- p.13 / Chapter 2.4.2 --- Seasonal and spatial variations in the abundance of planktonic copepods --- p.17 / Chapter 2.4.3 --- Seasonal variations in the relative abundance of dominant copepods --- p.27 / Chapter 2.4.4 --- Relationship between copepod abundance and chlorophyll a concentration --- p.26 / Chapter 2.4.5 --- Seasonal and spatial distribution and salinity and temperature preference of dominant copepods --- p.30 / Chapter 2.5 --- Discussion --- p.41 / Chapter 2.5.1 --- Seasonal variations in copepod abundance --- p.41 / Chapter 2.5.2 --- Seasonal and spatial variations in species diversity --- p.43 / Chapter 2.5.3 --- Seasonal and spatial distribution of dominant species --- p.45 / Chapter 2.5.4 --- Seasonal succession and spatial segregation of dominant copepods --- p.51 / Chapter 2.5.5 --- Seasonal and spatial distribution of non-dominant copepods --- p.52 / Chapter 2.6 --- Conclusion --- p.60 / Chapter Chapter 3. --- "Spatial and temporal distribution of marine cladocerans in Tolo Harbour, Hong Kong" --- p.61 / Chapter 3.1 --- Literature review --- p.61 / Chapter 3.1.1 --- Geographical and seasonal distribution of marine cladocerans --- p.61 / Chapter 3.1.2 --- Vertical distribution --- p.65 / Chapter 3.1.2.1 --- Diel vertical migration --- p.65 / Chapter 3.1.2.2 --- Marine cladocerans as epiplankters --- p.68 / Chapter 3.1.2.3 --- Diel vertical distribution of marine cladocerans --- p.69 / Chapter 3.1.3 --- Horizontal distribution --- p.70 / Chapter 3.1.4 --- Reproduction --- p.71 / Chapter 3.1.5 --- Feeding --- p.72 / Chapter 3.1.5.1 --- Food composition --- p.72 / Chapter 3.1.5.2 --- Diel feeding behaviour --- p.74 / Chapter 3.16 --- Site description of Tolo Harbour --- p.77 / Chapter 3.2 --- Introduction --- p.79 / Chapter 3.3 --- Materials and methods --- p.80 / Chapter 3.3.1 --- Field sampling --- p.80 / Chapter 3.3.1.1 --- Physical parameters --- p.80 / Chapter 3.3.1.2 --- Ambient chlorophyll concentration --- p.82 / Chapter 3.3.1.3 --- Zooplankton sampling --- p.82 / Chapter 3.3.1.4 --- Gut pigment content --- p.83 / Chapter 3.3.2 --- Measurement of gut evacuation rate --- p.84 / Chapter 3.3.2.1 --- Gut evacuation rate --- p.85 / Chapter 3.3.2.2 --- Clearance rate --- p.86 / Chapter 3.3.3 --- Zooplankton distribution --- p.86 / Chapter 3.3.3.1 --- Quantitative analysis --- p.86 / Chapter 3.3.4 --- Statistical analysis --- p.92 / Chapter 3.3.4.1 --- Overall population --- p.92 / Chapter 3.3.4.2 --- Size --- p.93 / Chapter 3.3.4.3 --- Reproductive condition --- p.94 / Chapter 3.3.4.4 --- Gut pigment content and gut clearance rate --- p.95 / Chapter 3.4 --- Results --- p.96 / Chapter 3.4.1 --- Physical parameters and chlorophyll concentration --- p.96 / Chapter 3.4.2 --- Spatial and temporal distribution of marine cladocerans --- p.102 / Chapter 3.4.2.1 --- Species composition and abundance --- p.102 / Chapter 3.4.2.2 --- Vertical and horizontal distribution in general population --- p.105 / Chapter 3.4.2.3 --- Vertical and horizontal patterns in size distribution --- p.110 / Chapter 3.4.2.4 --- Distribution of marine cladocerans at different stages --- p.118 / Chapter 3.4.3 --- Feeding ecology of marine cladocerans --- p.125 / Chapter 3.4.3.1 --- Did variation in gut pigment content --- p.125 / Chapter 3.4.3.2 --- Gut evacuation rate --- p.125 / Chapter 3.4.3.3 --- Diel changes in clearance rate of Penilia avirostris --- p.129 / Chapter 3.5 --- Discussion --- p.132 / Chapter 3.5.1 --- "Diel vertical and horizontal distribution of 3 marine podonids: Pseudevadne tergestina, Podon sp. and Pleopis schmackeri" --- p.135 / Chapter 3.5.2 --- Diel vertical and horizontal distribution of Penilia avirostris --- p.138 / Chapter 3.5.3 --- Size distribution of marine cladocerans --- p.140 / Chapter 3.5.4 --- Feeding behaviour of marine cladocerans --- p.142 / Chapter 3.6 --- Conclusion --- p.145 / References --- p.147

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 174-183.

Thesis (M.S. in environmental science)--Washington State University, August 2008. / Title from PDF title page (viewed on Mar. 11, 2009). "School of Earth and Environmental Science." Includes bibliographical references (p. 42-46).

Thesis (M.S.) in Oceanography--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 55-57).

Thesis (M.S.) in Oceanography--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 40-43).

Preliminary investigations of Saanich Inlet, Vancouver Island, British Columbia, indicated that there was a stratification in the depth of occurrence, during daytime, of the euphausiid Euphausia pacifica and the amphipods Cyphocaris challengeri and Orchomenella pinguis. The presence of an oxycline and a gradient in the carbon dioxide concentration suggested that the stratification was associated with these environmental factors. A programme was conducted between July 1962 and June 1963 to determine whether the stratification was a persistent phenomenon and whether physical and chemical characteristics of the water were associated with the distribution of the organisms. Clarke-Bumpus plankton samplers were towed above, within, and below the oxycline on seven cruises. The survival of the species was measured above, within, and below the oxycline, for exposures of 1 to 12 hours for Euphausia pacifica and Cyphocaris challengeri and of 9 to 24 hours for Orchomenella pinguis, by lowering specimens in cylinders which were in communication with the environment. Laboratory experiments measured the oxygen consumption of the species when carbon dioxide produced by the organisms in experimental chambers accumulated and when it was absorbed. Stratification was a persistent phenomenon in which Euphausia pacifica occupied the upper position, Orchomenella pinguis the lower position and Cyphocaris challengeri an inter-mediate or upper position in the daytime aggregation of organisms. The position of the aggregation was not influenced by temperature or salinity, but was related to the concentration of oxygen, and carbon dioxide. The field experiments showed that Orchomenella pinguis could tolerate lower oxygen and higher carbon dioxide concentrations for much longer durations of exposure than could the other two species. The laboratory experiments indicated Orchomenella pinguis and Cyphocaris challengeri consumed less oxygen than Euphausia pacifica, but Cyphocaris challengeri was more susceptible to high concentrations of carbon dioxide than the other species. These facts offer partial explanations for the stratification of the species. / Science, Faculty of / Zoology, Department of / Graduate

Populations of Euphausia pacifica Hansen in the Strait of Georgia region which have recently been commercially harvested were studied with respect to life history, distribution and population dynamics in order to examine aspects of the management of the resource. The potential use of local euphausiids as a food item for fish rearing was also evaluated through chemical analyses and feeding trials with juvenile coho salmon. The maximum life span in local populations was 19 months for males and 22 months for females. Spawning, which occurred from May to September, appeared to be closely related to phytoplankton abundance. First-year growth was maximal in summer (0.094 mm/day) but slowed in autumn and halted in winter. Growth in the following year showed a similar pattern. Males appeared to grow faster and experienced size-selective mortality following early maturity (11-12 mm). Survival increased with life phase changes between egg (6%/mo) and early adult stages (68%/mo) but declined sharply for individuals over 18 mm. Total biomass, B, in each population reached a maximum in October-November. Production by E. pacifica , P, in Saanich Inlet during July-November was 26.8 mgC/m²/day (P/B = 8.8), which is similar to that for herbivorous copepods, but higher than a previous estimate for E. pacifica . Juvenile coho salmon at 9 C showed mean growth rates of 3.8%/day on freeze-dried euphausiids compared to 3.0%, 2.7% and 3.1%/day on diets of euphausiid meal, frozen euphausiids and Oregon Moist Pellet, respectively. Local euphausiids have a well-balanced spectrum of amino acids in their proteins and high carotenoid concentrations (80-219 μ/g tissue) , making them suitable for use in aquacultural feeds. British Columbia's euphausiid fishery harvested about 100 metric tons during early 1977; the main uses are as an aquarium fish food and as a dietary supplement in salmon aquaculture. Yield calculations and other management considerations have indicated that the optimal harvesting time for E. pacifica is between October and December rather than from January to March as suggested by government guidelines on plankton harvesting, a limited and carefully monitored euphausiid fishery in the Strait of Georgia region appears to have potential value to the new plankton harvesting industry and to managers of associated fisheries who need further information on zooplankton population dynamics. / Science, Faculty of / Zoology, Department of / Graduate