My study focused on 1) fragmented seagrass interaction with hydrodynamics and 2) fragmented seagrass interaction with nutrients. My main research questions are: i) How do heterogeneous... Show more My study focused on 1) fragmented seagrass interaction with hydrodynamics and 2) fragmented seagrass interaction with nutrients. My main research questions are: i) How do heterogeneous patches in the seagrass bed interact with the hydrodynamic force? ii) How do the different seagrass properties (density, leaf length) and gap sizes influence flow development inside the gap? iii) How is the advective porewater exchange influenced by the presence of seagrass? and iv) How do the different hydrodynamic factors (diffusion, flow, wave and flow induced by wave) influence porewater exchange from sediment to water column? The results of these studies show that in controlled environments which exclude the effects of factors other than the hydrodynamic conditions, seagrass meadows have the ability to restore and re-homogenize themselves. A wide range of other factors may also play a role in determining whether heterogeneous patches become more or less homogeneous, such as nutrient cycling from sediment into the water column or vice versa, deposition of organic matter, erosion by waves or tidal currents, or animal grazing. This PhD thesis presents findings that elucidate the fundamental processes of seagrass–hydrodynamics interactions, which impact ecological processes such as patch and gap dynamics and advective porewater exchange. Show less
This thesis uses catastrophic stellar events (supernovae and stellar collisions) to investigate different aspects of their environment. The first part of the thesis examines what happens to... Show moreThis thesis uses catastrophic stellar events (supernovae and stellar collisions) to investigate different aspects of their environment. The first part of the thesis examines what happens to supernova remnants near supermassive black holes like the one in the Milky Way Galaxy. To do so, a technique is first developed for predicting the evolution of supernova remnants in non-uniform densities. This is used to demonstrate how supermassive black hole environments determine the evolution and lifetime of supernova remnants. Conversely, observations of supernova remnants can then be used to infer properties of the surroundings of supermassive black holes. Therefore, predictions are then given for the X-ray emission that could be observed from core-collapse supernova remnants in these regions. This emission can compete with other sources, such the accretion flow of the supermassive black hole itself. Next, the problem of a core-collapse supernova in a close binary system is considered, where the effect on the companion is studied to predict the properties of runaway stars from binaries disrupted after a supernova. Finally, simulations of blue stragglers, formed from stellar collisions, are used to learn about the globular clusters containing them. Estimating the collision times reveals details about the evolutionary history of the cluster. Show less
