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The main aim of this study was to investigate the immune system of the European flat oyster, Ostrea edulis, to determine the suitability of using immunological indices as potential biomonitors of water quality, particularly in reference to petroleum hydrocarbons. Immunocompetence was inferred through a measure of total and differential haemocyte concentration, larger granulocyte motility and diameter change, haemolymph hydrogen peroxide concentration and haemolymph lysozyme activity. Before any of these indices could be used as biomonitors, a baseline investigation had to be conducted. The baseline survey indicated that there was a strong seasonal signal for immunosuppression at the beginning of both the major and the minor spawning seasons. This immunosuppression appeared to be the result of partitioning of energy into the reproductive process. Historical occurrence of the two major diseases of this species occurred within these times. A neutral red uptake assay was applied to the haemocytes of O. edulis to investigate the sensitivity of this novel assay as an immunological indicator. The assay proved sensitive, reliable and consistent and supported the previous findings of pre-spawning immunomodulation. Oysters were exposed to the water soluble fraction of crude oil. Increasing concentrations of petroleum hydrocarbons resulted in an increase in haemolymph hydrogen peroxide concentration, increased haemocyte concentration and decreased large granulocyte motility. Haemolymph lysozyme activity and large granulocyte diameter change appeared to be influenced more by seasonal or physiological factors than by the contaminants. The increase in concentration of large granulocytes was accompanied by a decrease in large granulocyte viability which was confirmed by a reduction in the concentration of the neutral red dye retained by the haemocytes. Comparisons were made with immunological indices, concentrations of petroleum hydrocarbons in the water soluble fraction and with hydrocarbons retained in the tissue.

An investigation of luminescent sensing has been presented. Neutral Red, a common pH luminescent sensor, was shown to be an effective carbon dioxide sensor for the first time. Sensing experiments were performed both through fluorometric and fluorescent microscopy studies, giving rise to the possibility of carbon dioxide sensing for biological applications. Neutral Red was benchmarked against the well-established carbon dioxide sensor Pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt), HPTS. Neutral Red was shown to have improved response times and higher consistency within the sensing drift compared to HPTS. Trinuclear Au(I) complexes have previously shown to sense metal ions through changes in their luminescent properties. A computational study on d10-d10 interactions, which exist in complexes where Cu+, Ag+, and Au+ are intercalated with [Au(μ-C2,N3-ethylImidazolate)]3 in the form of both half and full sandwich adducts. Binding energies, total density plots, and Morse and Dunham analyses of potential energy surfaces are employed to better understand the metal-metal interactions and the effects of electron correlation, basis set superposition error, and dispersion of metallophilic interactions of the adduct complexes. As metal-metal interactions within these types of complexes become better understood, the tuning of trinuclear Au(I) complexes for luminescent sensing of metals becomes increasingly possible.

Abstract: The intertidal sea star Pisaster ochraceus lives in a wide range of wave-exposure conditions in the northeastern Pacific. Its body form and tube foot tenacity are both highly correlated with wave exposure. On wave-exposed shores sea stars attach to the substrate with higher tenacity, weigh significantly less per unit arm length, and have a narrower body and arms. Water velocity explained over 99% of the variation in average body shape and 92% of the variation in average tenacity. Reciprocal transplants revealed that both traits responded plastically to changes in wave exposure, so the variation is therefore primarily ecophenotypic. This plasticity is likely also adaptive, allowing Pisaster to respond to variation in flow in both space and time. Both phenotypic responses probably act to reduce dislodgement risk – changes in tenacity influence attachment force and changes in body form modify the drag and lift experienced, which are the main effectors of dislodgement.