Pyrolysis mass spectrometry (PyMS) is a rapid, automated analytical technique that is used for chemical and biological characterisation of organisms. It has been limited in its use outside the discipline of microbiology and has rarely been applied to the analysis of multi-cellular organisms. This study aimed to investigate the potential of using PyMS as a routine analytical tool to resolve problems in marine algal systematics. The technical constraints of PyMS were also examined. The effect of sample concentration proved to be an important consideration for the production of meaningful results. PyMS analysis of macroalgae from the order Fucales demonstrated that this technique was robust to the influence of environmental variability and challenged the assertion that it is limited to use as a phenotypic technique only. Characterisation of samples was also possible at the sub-species level. Experimentally induced variation among cultures of the diatom Skeletonema costatum, including silicate limitation, low salinity and reduced irradiance, was detectable by PyMS. PyMS is subject to technical limitations including day to day variability among spectral data and does not produce a permanent classification. This study showed that PyMS is a highly discriminatory, sensitive technique that is capable of resolving chemical and biological variability among marine algae.

We develop a new geometric method of understanding principal G-Higgs bundles through their spectral data, for G a real form of a complex Lie group. In particular, we consider the case of G a split real form, as well as G = SL(2,R), U(p,p), SU(p,p), and Sp(2p,2p). Further, we give some applications of our results, and discuss open questions.

<p> Invasive species have developed long-term relationships with humans, especially since the start of the Industrial Revolution, and they have caused immense damage to native environments, ecosystems, and economies. An emerging invasive insect that has recently gained considerable attention is the spotted lanternfly (SLF). Early detection of SLF infestations in new areas or at low densities can lead to a more efficacious management and reduce costs associated with control them. Developing approaches to detect the presence of invasive species, favorable habitats for their establishment, and predicting potential spread will be crucial for effective management strategies to protect native environments and the economy. The goal of my thesis is to improve the understanding of how spotted lanternfly changes the spectral profile and chemical composition of host tree species. I found that spotted lanternfly feeding influences host canopy chemical and spectral properties. Specifically, I was able to use leaf-level hyperspectral measurements to differentiate SLF infestations levels in silver maple and red maple, shown by my first chapter, along with black walnut in my second chapter. Further, I was able to find differences in phenolic compounds in response to SLF infestations in red maple. The results of my study have the potential to be scaled up from leaf-level to landscape-level measurements. I have identified spectral signatures in red maple, silver maple, and black walnut that can be used to identify infestations from spectral data collected from UAVs or satellites. This potentially provides a new method for detection that is easier than traditional ones (like manual scouting and trapping). </p>