Source: Dissertation Abstracts International, Volume: 34-06, Section: B, page: 2813. / Thesis (Ph.D.)--The Florida State University, 1973.

A field examination was conducted on a subtidal population of the five-slotted sand dollar Mellita quinquiesperforata and its impact on the resident benthic community. The mean monthly density of the sand-dollar population was very high in the beginning of the investigation (35.6/0.25 m('2)), declined sharply for six months, and then was steady for the remaining two years of the study (range 3-7/.025m('2)). The spatial dispersion, growth rate, and recruitment pattern of the population appear related to depth. / The major meiofaunal taxa generally were unaffected by the passage of sand dollar. Recently, (i.e., minutes) disturbed sediments contained significantly higher total nematode and lower total foraminifera abundances. In addition, only one species of harpacticoid copepod, Halectinosoma sp., was found in significantly lower abundances within sand-dollar trails. All other species were apparently unaffected. / The infaunal polychaete and bivalve assemblages present within the sand-dollar bed similarly demonstrated limited effects as a result of sand-dollar disturbance. The sand-dollar bed was dominated by burrowing polychaete families, such as Paranidae, Pilargidae, and Syllidae. Spiondae was the dominant tube-building polychaete family. The bivalves were dominated by Tellinidae. In general, the majority of infauna were resilient to sand-dollar movement. Only two species were negatively affected by sand-dollar movement: the spionid polychaete Prionospio pygmaea and the tellinid bivalve Tellina sp. A. In both cases, small individuals demonstrated higher abundances within sand-dollar-free patches. In general, it appeared that post-settlement interactions resulted in the lower abundances observed within the sand-dollar bed. Live observations revealed that the sand dollar did not cause the immediate mortality of either the spionid or the tellinid. Frequent feeding disruption was postulated as the possible mechanism causing the reduced abundances. / Source: Dissertation Abstracts International, Volume: 47-05, Section: B, page: 1821. / Thesis (Ph.D.)--The Florida State University, 1986.

Source: Dissertation Abstracts International, Volume: 30-12, Section: B, page: 5581. / Thesis (Ph.D.)--The Florida State University, 1969.

<p>Ocean fronts are dynamic gradients that divide waters with differing hydrographic properties. Fronts also play important ecological roles in structuring plankton distributions, modulating primary and secondary production, and delineating predator foraging areas. Here, I utilize autonomous &ldquo;<i> Spray</i>&rdquo; ocean gliders to describe the spatial and seasonal distribution of deep-water fronts and their impact on the plankton within the Southern California Current System (SCCS). </p><p> To test the suitability of the <i>Spray</i>&rsquo;s 750 kHz acoustic doppler profilers (ADP) for mapping zooplankton distributions, I first present results from a seatruthing study in which I mounted an ADP on a Mocness plankton net. I show that the relative mean volume backscatter (rMVBS) measured by the ADP is correlated with the summed zooplankton cross-sectional area (a proxy for biomass). I also find that the relationship between rMVBS and zooplankton biomass is strongest for zooplankters with an estimated spherical diameter greater than 1.6 mm. Observed rMVBS was best explained by euphausiid and copepod biomass. </p><p> From <i>Spray</i> cross-shore sections between October, 2006 and December, 2011, I identified 154 distinct surface layer density fronts. The strongest and most numerous fronts occurred in spring, and were located closer to the coast, whereas summer and fall fronts were found further offshore. Fronts were weakest and least numerous in winter. Across all seasons, fronts structured plankton distributions. Horizontal gradients in physical variables (e.g., surface density, temperature, and salinity) co-varied with horizontal gradients in MVBS and Chl<i>-a</i> fluorescence, and the magnitude of biological gradients was higher at frontal areas compared with non-frontal areas. Frontal areas were also clearly associated with elevated Chl<i> -a</i> and zooplankton acoustic backscatter. </p><p> Fronts divided distinct plankton habitats and associated assemblages. Chlorophyll-a fluorescence maxima and euphotic zones were deeper offshore of fronts. The amplitude of diel vertical migration by zooplankton also increased offshore, in association with increased optical transparency in the upper ocean. Additionally, ADP data indicate that zooplankton assemblages change across fronts. I employ an inverse acoustic model to estimate zooplankton size spectra, inferring that larger-bodied zooplankters contributed a greater proportion to overall biomass inshore of these fronts. Vertically-stratified zooplankton samples from both inshore and offshore regions corroborated the model results. </p>

Cyanobacteria make up 30-80% of autotrophic biomass in high-nutrient low-chlorophyll regions of the sea, but few measurements of their nutrient requirements for growth exist. We measured the elemental content of five strains of marine Synechococcus (CCMP2515, -838, -837, -1334 and -2370) during exponential growth in Fe-replete and Fe-deplete seawater. Iron-limited cells showed a substantial increase in volume and carbon, nitrogen and phosphorus quotas. The average molar C: N, and C: P ratios of the Synechococcus strains was not significantly affected by Fe nutritional state, but the N: P ratio declined as Fe became limiting (p = 0.078). The Redfield ratio of Fe-replete Synechococcus was thus 102 ± 25 mol C: 16.2 ± 3.8 mol N: 1 mol P and of Fe-deplete Synechococcus was 91.9 ± 21.1 mol C: 11.7 ± 5.7 mol N: 1 mol P. In Fe-deplete medium, Fe quotas decreased to 63.5 ± 36.3 mmol Fe mol-1 C (5.69 ± 2.79 mmol Fe mol-1 P) and growth rates dropped to 0.5 - 0.8 mmax. The isolates from coastal regions contained on average less Fe normalized per cell, per C and per P, than the oceanic strains despite similar amounts of Fe in the growth medium. Manganese and copper quotas were remarkably similar in all Synechococcus in nutrient-replete medium (3.76 ± 1.04 mmol Mn mol-1 C and 2.69 ± 0.66 mmol Cu mol-1 C). Iron limitation increased the average Mn and Cu quotas, but the response of individual strains was variable. Nickel: C ratios were highest in nutrient-replete medium in CCMP2370 and -2515, two Synechococcus known to possess Ni-SOD. The strains from the open sea were not well adapted to grow at low Fe and had iron use efficiencies that were two-fold lower than the coastal strains (1.22 x 104 vs 0.52 x 104 mol C mol-1 Fe d-1, respectively). / Les cyanobactéries représentent 30-80% de la biomasse autotrophique en haute mer, où la concentration de la chlorophylle est basse et les concentrations des macro-nutriments élevés, mais peu de mesures existent sur leur demande nutritive relativement à la croissance. Nous avons mesuré le contenu élémentaire de 5 souches de l'espèce Synechococcus (CCMP2515, -838, -837, -1334, -2370) durant leur croissance exponentielle dans de l'eau marine limitée et non-limitée en fer (Fe). Les cellules limitées en Fe ont montré une augmentation substantielle dans leurs volumes et leurs concentrations cellulaires de carbone (C), azote (N) et phosphore (P). Les moyennes molaires des rapports C: N et C: P n'ont pas été affectées de façon significative par l'état nutritif en Fe, mais le rapport N: P a décliné lorsque le fer est devenu limitant (p = 0.078). Le rapport Redfield des représentants de Synechococcus riches en Fe était 102 ± 25 mol C: 16.2 ± 3.8 mol N: 1 mol P et pour ceux limités en Fe était 91.9 ± 21.1 mol C: 11.7 ± 5.7 mol N: 1 mol P. Dans le médium pauvre en Fe, la concentration cellulaire de Fe normalisée au C a diminué de 109 ± 15 à 63.5 ± 36.3 mmol Fe mol-1 C (5.69 ± 2.79 mmol Fe mol-1 P) et les taux de croissance relative ont baissés à 0.5-0.8 mmax. Les souches côtières contenaient en moyenne moins de Fe normalisé par cellule, par unité de carbone et par unité de phosphore, que les souches océaniques malgré les quantités semblables de Fe dans le médium de croissance. Les concentrations cellulaires de manganèse (Mn) et de cuivre (Cu) étaient remarquablement semblables dans tous les souches de Synechococcus (3.76 ± 1.04 mmol Mn mol-1 C and 2.69 ± 0.66 mmol Cu mol-1 C). La limitation de Fe a augmenté les concentrations cellulaires de Mn et de Cu, mais la réponse des souches individuelles était variable. Les rapports Ni: C étaient les plus élevés dans CC

Sea ice characteristics were studied in relation to nutrient dynamics, biomass and community structure and composition of ice biota from the Gulf of St. Lawrence at landfast and drifting ice stations in the Magdalen Islands area. The instability of the ice substrate was demonstrated with respect to short duration of cover (8 weeks), ice melt and rafting processes. / The study of nutrient dynamics in ice and in seawater suggests silicates and nitrogen (NO$ sb2$+NO$ sb3$+NH$ sb4$) limitation at landfast ice stations, as well as in situ regeneration of phosphorus in the bottom ice sections. No correlation was found between microalgal biomass and nutrients, but specific growth rates were in the lower range of values reported for Arctic ice algae. / The composition of the microalgal ice biota revealed two types of communities. The first type was composed of a majority of pennate diatoms (abundance $>$ 98%), with dominant species such as Nitzschia cylindrus, N. polaris and Navicula kariana, similar to Arctic landfast ice biota communities. The second type was composed of a high percentage of centric diatoms (abundance $>$ 46%) due to the abundance of the planktonic diatom Thalassiosira norderskioldii. Community structure and composition are discussed with respect to the instability of the ice substrate, and the comparison between landfast and drifting pack ice.

Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references. / Electronic reproduction. / Also available by subscription via World Wide Web / x, 202 leaves, bound ill. (some col.) 29 cm

Thesis (Ph.D.)--University of California, Santa Barbara, 2006. / (UnM)AAI3218850. Adviser: Barbara B. Prezelin. Source: Dissertation Abstracts International, Volume: 67-05, Section: B, page: 2405.

Thesis (Ph.D.)--University of Southern California, 2007. / (UMI)AAI3262735. Source: Dissertation Abstracts International, Volume: 68-05, Section: B, page: 2866. Adviser: David A. Caron.

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